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1. How education and GDP drive the COVID-19 vaccination campaign

Author

Vu M. Ngo, Klaus F. Zimmermann, Phuc V. Nguyen, Toan L. D. Huynh, and Huan H. Nguyen

Subjects
COVID-19, Educational development, Political regimes, Economic strength, Vaccination, Public aspects of medicine, RA1-1270
Abstract

Abstract Background Since vaccination is the decisive factor for controlling the COVID-19 pandemic, it is important to understand the process of vaccination success which is not well understood on a global level. The study is the first to judge the now completed "first wave" of the vaccination efforts. The analysis is very relevant for the understanding why and where the vaccination process observed got stuck by the end of 2021. Methods Using data from 118 countries globally and weighted least squared and survival analysis, we identify a variety of factors playing crucial roles, including the availability of vaccines, pandemic pressures, economic strength measured by Gross Domestic Product (GDP), educational development, and political regimes. Results Examining the speed of vaccinations across countries until the Fall of 2021 when the global process got stuck, we find that initially authoritarian countries are slow in the vaccination process, while education is most relevant for scaling up the campaign, and the economic strength of the economies drives them to higher vaccination rates. In comparison to North and Middle America, European and Asian countries vaccinated initially fast for 5% and 10% vaccination rate thresholds, but became rather slow reaching the 30% vaccination level and above. The findings are robust to various applied estimation methods and model specifications. Conclusions Democratic countries are much faster than authoritarian countries in their vaccination campaigns when controlling for other factors. This finding suggests that the quality of government and the political environment play a key role in popular support for government policies and programs. However, despite the early success of their vaccination campaigns, the democratic country group has been confronted with strong concerns of vaccine reluctance among their vast populations, indicating the two most potent variables explaining the speed of the COVID-19 vaccination campaign are education and economic conditions.

Published
2022
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2. Patterning of supported gold monolayers via chemical lift-off lithography

Author

Liane S. Slaughter, Kevin M. Cheung, Sami Kaappa, Huan H. Cao, Qing Yang, Thomas D. Young, Andrew C. Serino, Sami Malola, Jana M. Olson, Stephan Link, Hannu Häkkinen, Anne M. Andrews, and Paul S. Weiss

Subjects
chemical patterning, hybrid material, monolayer, soft lithography, two-dimensional material, Technology, Chemical technology, TP1-1185, Science, Physics, QC1-999
Abstract

The supported monolayer of Au that accompanies alkanethiolate molecules removed by polymer stamps during chemical lift-off lithography is a scarcely studied hybrid material. We show that these Au–alkanethiolate layers on poly(dimethylsiloxane) (PDMS) are transparent, functional, hybrid interfaces that can be patterned over nanometer, micrometer, and millimeter length scales. Unlike other ultrathin Au films and nanoparticles, lifted-off Au–alkanethiolate thin films lack a measurable optical signature. We therefore devised fabrication, characterization, and simulation strategies by which to interrogate the nanoscale structure, chemical functionality, stoichiometry, and spectral signature of the supported Au–thiolate layers. The patterning of these layers laterally encodes their functionality, as demonstrated by a fluorescence-based approach that relies on dye-labeled complementary DNA hybridization. Supported thin Au films can be patterned via features on PDMS stamps (controlled contact), using patterned Au substrates prior to lift-off (e.g., selective wet etching), or by patterning alkanethiols on Au substrates to be reactive in selected regions but not others (controlled reactivity). In all cases, the regions containing Au–alkanethiolate layers have a sub-nanometer apparent height, which was found to be consistent with molecular dynamics simulations that predicted the removal of no more than 1.5 Au atoms per thiol, thus presenting a monolayer-like structure.

Published
2017
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3. Formation of Linear Plasmonic Heterotrimers Using Nanoparticle Docking to DNA Origami Cages

Author

Zhang, Yehan, Allen, A’Lester C, Petrek, Zachary J, Cao, Huan H, Kumar, Devanshu, Goodlad, Melissa C, Martinez, Vianna G, Singh, Jasdip, Zhang, Jin Z, and Ye, Tao

Subjects
Macromolecular and Materials Chemistry, Engineering, Chemical Sciences, Nanotechnology, Bioengineering, 1.1 Normal biological development and functioning, Generic health relevance, Technology, Physical Chemistry, Chemical sciences
Published
2024

4. Vaccines for Mucosal Immunity to Combat Emerging Infectious Diseases

Author

Frederik W. van Ginkel, Huan H. Nguyen, and Jerry R. McGhee

Subjects
mucosal immune system, mucosal pathogens, mucosal vaccines, United States, Medicine, Infectious and parasitic diseases, RC109-216
Abstract

The mucosal immune system consists of molecules, cells, and organized lymphoid structures intended to provide immunity to pathogens that impinge upon mucosal surfaces. Mucosal infection by intracellular pathogens results in the induction of cell-mediated immunity, as manifested by CD4-positive (CD4+) T helper-type 1 cells, as well as CD8+ cytotoxic T-lymphocytes. These responses are normally accompanied by the synthesis of secretory immunoglobulin A (S-IgA) antibodies, which provide an important first line of defense against invasion of deeper tissues by these pathogens. New-generation live, attenuated viral vaccines, such as the cold-adapted, recombinant nasal influenza and oral rotavirus vaccines, optimize this form of mucosal immune protection. Despite these advances, new and reemerging infectious diseases are tipping the balance in favor of the parasite; continued mucosal vaccine development will be needed to effectively combat these new threats.

Published
2000
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6. Mucosal vaccination with recombinant adenovirus encoding nucleoprotein provides potent protection against influenza virus infection.

Author

So-Hee Kim, Joo Young Kim, Youngjoo Choi, Huan H Nguyen, Man Ki Song, and Jun Chang

Subjects
Medicine, Science
Abstract

Influenza vaccines that target the highly variable surface glycoproteins hemagglutinin and neuraminidase cause inconvenience of having vaccination every year. For this reason, development of universal vaccines targeting conserved viral components is needed. In this study, we generated recombinant adenovirus (rAd) vaccine encoding nucleoprotein (NP) of A/PR/8/34 influenza virus, designated rAd/NP. BALB/c mice were immunized intranasally or sublingually with rAd/NP vaccine and subsequently challenged with lethal doses of heterologous as well as homologous influenza viruses. We found that intranasal immunization of rAd/NP elicited strong mucosal IgA responses as well as stronger CD8 T-cell responses toward immunodominant K(d)-restricted NP147-155 epitope than sublingual immunization. Importantly, only single intranasal but not sublingual immunization of rAd/NP provides potent protection against both homologous and heterologous influenza virus challenges. These results suggest that recombinant rAd/NP could be a universal vaccine candidate for mucosal administration against influenza virus.

Published
2013
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7. Sublingual immunization with a live attenuated influenza a virus lacking the nonstructural protein 1 induces broad protective immunity in mice.

Author

Hae-Jung Park, Boris Ferko, Young-Ho Byun, Joo-Hye Song, Gye-Yeong Han, Elisabeth Roethl, Andrej Egorov, Thomas Muster, Baiklin Seong, Mi-Na Kweon, Manki Song, Cecil Czerkinsky, and Huan H Nguyen

Subjects
Medicine, Science
Abstract

The nonstructural protein 1 (NS1) of influenza A virus (IAV) enables the virus to disarm the host cell type 1 IFN defense system. Mutation or deletion of the NS1 gene leads to attenuation of the virus and enhances host antiviral response making such live-attenuated influenza viruses attractive vaccine candidates. Sublingual (SL) immunization with live influenza virus has been found to be safe and effective for inducing protective immune responses in mucosal and systemic compartments. Here we demonstrate that SL immunization with NS1 deleted IAV (DeltaNS1 H1N1 or DeltaNS1 H5N1) induced protection against challenge with homologous as well as heterosubtypic influenza viruses. Protection was comparable with that induced by intranasal (IN) immunization and was associated with high levels of virus-specific antibodies (Abs). SL immunization with DeltaNS1 virus induced broad Ab responses in mucosal and systemic compartments and stimulated immune cells in mucosa-associated and systemic lymphoid organs. Thus, SL immunization with DeltaNS1 offers a novel potential vaccination strategy for the control of influenza outbreaks including pandemics.

Published
2012
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8. Prophylactic and therapeutic efficacy of avian antibodies against influenza virus H5N1 and H1N1 in mice.

Author

Huan H Nguyen, Terrence M Tumpey, Hae-Jung Park, Young-Ho Byun, Linh D Tran, Van D Nguyen, Paul E Kilgore, Cecil Czerkinsky, Jacqueline M Katz, Baik Lin Seong, Jae Min Song, Young Bong Kim, Hoa T Do, Tung Nguyen, and Cam V Nguyen

Subjects
Medicine, Science
Abstract

BACKGROUND: Pandemic influenza poses a serious threat to global health and the world economy. While vaccines are currently under development, passive immunization could offer an alternative strategy to prevent and treat influenza virus infection. Attempts to develop monoclonal antibodies (mAbs) have been made. However, passive immunization based on mAbs may require a cocktail of mAbs with broader specificity in order to provide full protection since mAbs are generally specific for single epitopes. Chicken immunoglobulins (IgY) found in egg yolk have been used mainly for treatment of infectious diseases of the gastrointestinal tract. Because the recent epidemic of highly pathogenic avian influenza virus (HPAIV) strain H5N1 has resulted in serious economic losses to the poultry industry, many countries including Vietnam have introduced mass vaccination of poultry with H5N1 virus vaccines. We reasoned that IgY from consumable eggs available in supermarkets in Vietnam could provide protection against infections with HPAIV H5N1. METHODS AND FINDINGS: We found that H5N1-specific IgY that are prepared from eggs available in supermarkets in Vietnam by a rapid and simple water dilution method cross-protect against infections with HPAIV H5N1 and related H5N2 strains in mice. When administered intranasally before or after lethal infection, the IgY prevent the infection or significantly reduce viral replication resulting in complete recovery from the disease, respectively. We further generated H1N1 virus-specific IgY by immunization of hens with inactivated H1N1 A/PR/8/34 as a model virus for the current pandemic H1N1/09 and found that such H1N1-specific IgY protect mice from lethal influenza virus infection. CONCLUSIONS: The findings suggest that readily available H5N1-specific IgY offer an enormous source of valuable biological material to combat a potential H5N1 pandemic. In addition, our study provides a proof-of-concept for the approach using virus-specific IgY as affordable, safe, and effective alternative for the control of influenza outbreaks, including the current H1N1 pandemic.

Published
2010
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9. Seeding the Self-Assembly of DNA Origamis at Surfaces.

Author

Cao, Huan H, Abel, Gary R, Gu, Qufei, Gueorguieva, Gloria-Alexandra V, Zhang, Yehan, Nanney, Warren A, Provencio, Eric T, and Ye, Tao

Subjects
DNA nanotechnology, DNA origami, atomic force microscopy, biomolecular surface chemistry, force spectroscopy, self-assembly, supramolecular self-assembly, Nanoscience & Nanotechnology
Abstract

Unlike supramolecular self-assembly methods that can organize many distinct components into designer shapes in a homogeneous solution (e.g., DNA origami), only relatively simple, symmetric structures consisting of a few distinct components have been self-assembled at solid surfaces. As the self-assembly process is confined to the surface/interface by mostly nonspecific attractive interactions, an open question is how these interfacial interactions affect multicomponent self-assembly. To gain a mechanistic understanding of the roles of the surface environment in DNA origami self-assembly, here we studied the oligonucleotide-assisted folding of a long single-stranded DNA (ssDNA scaffold) that was end-tethered to a dynamic surface, which could actively regulate the DNA-surface interactions. The results showed that even weak surface attractions can lead to defective structures by inhibiting the merging of multiple domains into complete structures. A combination of surface anchoring and deliberate regulation of DNA-surface interactions allowed us to depart from the existing paradigm of surface confinement via nonspecific interactions and enabled DNA origami folding to proceed in a solution-like environment. Importantly, our strategy retains the key advantages of surface-mediated self-assembly. For example, surface-anchored oligonucleotides could sequence-specifically initiate the growth of DNA origamis of specific sizes and shapes. Our work enables information to be encoded into a surface and expressed into complex DNA surface architectures for potential nanoelectronic and nanophotonic applications. In addition, our approach to surface confinement may facilitate the 2D self-assembly of other molecular components, such as proteins, as maintaining conformational freedom may be a general challenge in the self-assembly of complex structures at surfaces.

Published
2020

11. Single Molecule Profiling of Molecular Recognition at a Model Electrochemical Biosensor

Author

Gu, Qufei, Nanney, Warren, Cao, Huan H, Wang, Haiyang, and Ye, Tao

Subjects
Nanotechnology, Bioengineering, Biotechnology, 1.1 Normal biological development and functioning, Underpinning research, Generic health relevance, Biosensing Techniques, DNA, DNA Probes, Electrochemical Techniques, Microscopy, Atomic Force, Particle Size, Surface Properties, Chemical Sciences, General Chemistry
Abstract

The spatial arrangement of target and probe molecules on the biosensor is a key aspect of the biointerface structure that ultimately determines the properties of interfacial molecular recognition and the performance of the biosensor. However, the spatial patterns of single molecules on practical biosensors have been unknown, making it difficult to rationally engineer biosensors. Here, we have used high-resolution atomic force microscopy to map closely spaced individual probes as well as discrete hybridization events on a functioning electrochemical DNA sensor surface. We also applied spatial statistical methods to characterize the spatial patterns at the single molecule level. We observed the emergence of heterogeneous spatiotemporal patterns of surface hybridization of hairpin probes. The clustering of target capture suggests that hybridization may be enhanced by proximity of probes and targets that are about 10 nm away. The unexpected enhancement was rationalized by the complex interplay between the nanoscale spatial organization of probe molecules, the conformational changes of the probe molecules, and target binding. Such molecular level knowledge may allow one to tailor the spatial patterns of the biosensor surfaces to improve the sensitivity and reproducibility.

Published
2018

13. Aptamer Recognition of Multiplexed Small-Molecule-Functionalized Substrates

Author

Nakatsuka, Nako, Cao, Huan H, Deshayes, Stephanie, Melkonian, Arin L, Kasko, Andrea M, Weiss, Paul S, and Andrews, Anne M

Subjects
Neurosciences, Biotechnology, oligonucleotide, neurotransmitter, chemical patterning, microfluidics, self-assembled monolayers, molecular recognition, fluorescence microscopy, Chemical Sciences, Engineering, Nanoscience & Nanotechnology
Abstract

Aptamers are chemically synthesized oligonucleotides or peptides with molecular recognition capabilities. We investigated recognition of substrate-tethered small-molecule targets, using neurotransmitters as examples, and fluorescently labeled DNA aptamers. Substrate regions patterned via microfluidic channels with dopamine or   l-tryptophan were selectively recognized by previously identified dopamine or l-tryptophan aptamers, respectively. The on-substrate dissociation constant determined for the dopamine aptamer was comparable to, though, slightly greater than the previously determined solution dissociation constant. Using prefunctionalized neurotransmitter-conjugated oligo(ethylene glycol) alkanethiols and microfluidics patterning, we produced multiplexed substrates to capture and to sort aptamers. Substrates patterned with l-3,4-dihydroxyphenylalanine, l- threo-dihydroxyphenylserine, and l-5-hydroxytryptophan enabled comparison of the selectivity of the dopamine aptamer for different targets via simultaneous determination of in situ binding constants. Thus, beyond our previous demonstrations of recognition by protein binding partners (i.e., antibodies and G-protein-coupled receptors), strategically optimized small-molecule-functionalized substrates show selective recognition of nucleic acid binding partners. These substrates are useful for side-by-side target comparisons and future identification and characterization of novel aptamers targeting neurotransmitters or other important small molecules.

Published
2018

14. Small-Molecule Patterning via Prefunctionalized Alkanethiols

Author

Cao, Huan H, Nakatsuka, Nako, Deshayes, Stephanie, Abendroth, John M, Yang, Hongyan, Weiss, Paul S, Kasko, Andrea M, and Andrews, Anne M

Subjects
Nanotechnology, Biotechnology, Bioengineering, biorecognition, chemical patterning, fluorescence microscopy, lithography, neurotransmitter, self-assembly, Chemical Sciences, Engineering, Materials
Abstract

Interactions between small molecules and biomolecules are important physiologically and for biosensing, diagnostic, and therapeutic applications. To investigate these interactions, small molecules can be tethered to substrates through standard coupling chemistries. While convenient, these approaches co-opt one or more of the few small-molecule functional groups needed for biorecognition. Moreover, for multiplexing, individual probes require different surface functionalization chemistries, conditions, and/or protection/deprotection strategies. Thus, when placing multiple small-molecules on surfaces, orthogonal chemistries are needed that preserve all functional groups and are sequentially compatible. Here, we approach high-fidelity small-molecule patterning by coupling small-molecule neurotransmitter precursors, as examples, to monodisperse asymmetric oligo(ethylene glycol)alkanethiols during synthesis and prior to self-assembly on Au substrates. We use chemical lift-off lithography to singly and doubly pattern substrates. Selective antibody recognition of pre-functionalized thiols was comparable to or better than recognition of small molecules functionalized to alkanethiols after surface assembly. These findings demonstrate that synthesis and patterning approaches that circumvent sequential surface conjugation chemistries enable biomolecule recognition and afford gateways to multiplexed small-molecule functionalized substrates.

Published
2018

15. Image segmentation with dynamic artifacts detection and bias correction

Author

Zosso, Dominique, An, Jing, Stevick, James, Takaki, Nicholas, Weiss, Morgan, Slaughter, Liane S, Cao, Huan H, Weiss, Paul S, and Bertozzi, Andrea L

Subjects
Pure Mathematics, Mathematical Sciences, Biomedical Imaging, Image segmentation, artifacts, bias, Retinex, dynamic labeling, Chan-Vese, levelset method, threshold dynamics, MBO, Numerical and Computational Mathematics, Pure mathematics
Abstract

Region-based image segmentation is well-addressed by the ChanVese (CV) model. However, this approach fails when images are affected by artifacts (outliers) and illumination bias that outweigh the actual image contrast. Here, we introduce a model for segmenting such images. In a single energy functional, we introduce 1) a dynamic artifact class preventing intensity outliers from skewing the segmentation, and 2), in Retinex-fashion, we decompose the image into a piecewise-constant structural part and a smooth bias part. The CV-segmentation terms then only act on the structure, and only in regions not identified as artifacts. The segmentation is parameterized using a phase-field, and efficiently minimized using threshold dynamics. We demonstrate the proposed model on a series of sample images from diverse modalities exhibiting artifacts and/or bias. Our algorithm typically converges within 10-50 iterations and takes fractions of a second on standard equipment to produce meaningful results. We expect our method to be useful for damaged images, and anticipate use in applications where artifacts and bias are actual features of interest, such as lesion detection and bias field correction in medical imaging, e.g., in magnetic resonance imaging (MRI).

Published
2017

16. Patterning of supported gold monolayers via chemical lift-off lithography.

Author

Slaughter, Liane S, Cheung, Kevin M, Kaappa, Sami, Cao, Huan H, Yang, Qing, Young, Thomas D, Serino, Andrew C, Malola, Sami, Olson, Jana M, Link, Stephan, Häkkinen, Hannu, Andrews, Anne M, and Weiss, Paul S

Subjects
chemical patterning, hybrid material, monolayer, soft lithography, two-dimensional material, Analytical Chemistry, Other Chemical Sciences, Nanotechnology
Abstract

The supported monolayer of Au that accompanies alkanethiolate molecules removed by polymer stamps during chemical lift-off lithography is a scarcely studied hybrid material. We show that these Au-alkanethiolate layers on poly(dimethylsiloxane) (PDMS) are transparent, functional, hybrid interfaces that can be patterned over nanometer, micrometer, and millimeter length scales. Unlike other ultrathin Au films and nanoparticles, lifted-off Au-alkanethiolate thin films lack a measurable optical signature. We therefore devised fabrication, characterization, and simulation strategies by which to interrogate the nanoscale structure, chemical functionality, stoichiometry, and spectral signature of the supported Au-thiolate layers. The patterning of these layers laterally encodes their functionality, as demonstrated by a fluorescence-based approach that relies on dye-labeled complementary DNA hybridization. Supported thin Au films can be patterned via features on PDMS stamps (controlled contact), using patterned Au substrates prior to lift-off (e.g., selective wet etching), or by patterning alkanethiols on Au substrates to be reactive in selected regions but not others (controlled reactivity). In all cases, the regions containing Au-alkanethiolate layers have a sub-nanometer apparent height, which was found to be consistent with molecular dynamics simulations that predicted the removal of no more than 1.5 Au atoms per thiol, thus presenting a monolayer-like structure.

Published
2017

17. Prospective multicenter study to evaluate capsule endoscopy competency using a validated assessment tool

Author

Rajan, Elizabeth, Martinez, Manuel, Gorospe, Emmanuel, Al Bawardy, Badr, Dobashi, Akira, Mara, Kristin C., Hansel, Stephanie L., Bruining, David H., Murray, Joseph A., Leggett, Cadman L., Nehra, Vandana, Iyer, Prasad G., Pasha, Shabana F., Leighton, Jonathan A., Shiff, Arthur D., Gurudu, Suryakanth R., Raffals, Laura E., Lavey, Crystal, Katzka, David A., and Chen, Chien-Huan H.

Published
2020
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18. Controlled DNA Patterning by Chemical Lift-Off Lithography: Matrix Matters.

Author

Cao, Huan H, Nakatsuka, Nako, Serino, Andrew C, Liao, Wei-Ssu, Cheunkar, Sarawut, Yang, Hongyan, Weiss, Paul S, and Andrews, Anne M

Subjects
Polyethylene Glycols, Dimethylpolysiloxanes, Sulfhydryl Compounds, DNA, Microscopy, Atomic Force, Nucleic Acid Hybridization, Printing, Photoelectron Spectroscopy, DNA hybridization, alkanethiol patterning, chemical lift-off lithography, nucleotide arrays, self-assembled monolayers, Genetics, Nanoscience & Nanotechnology
Abstract

Nucleotide arrays require controlled surface densities and minimal nucleotide-substrate interactions to enable highly specific and efficient recognition by corresponding targets. We investigated chemical lift-off lithography with hydroxyl- and oligo(ethylene glycol)-terminated alkanethiol self-assembled monolayers as a means to produce substrates optimized for tethered DNA insertion into post-lift-off regions. Residual alkanethiols in the patterned regions after lift-off lithography enabled the formation of patterned DNA monolayers that favored hybridization with target DNA. Nucleotide densities were tunable by altering surface chemistries and alkanethiol ratios prior to lift-off. Lithography-induced conformational changes in oligo(ethylene glycol)-terminated monolayers hindered nucleotide insertion but could be used to advantage via mixed monolayers or double-lift-off lithography. Compared to thiolated DNA self-assembly alone or with alkanethiol backfilling, preparation of functional nucleotide arrays by chemical lift-off lithography enables superior hybridization efficiency and tunability.

Published
2015

19. Fabrication of High-Performance Ultrathin In2O3 Film Field-Effect Transistors and Biosensors Using Chemical Lift-Off Lithography

Author

Kim, Jaemyung, Rim, You Seung, Chen, Huajun, Cao, Huan H, Nakatsuka, Nako, Hinton, Hannah L, Zhao, Chuanzhen, Andrews, Anne M, Yang, Yang, and Weiss, Paul S

Subjects
Engineering, Materials Engineering, Chemical Sciences, Aptamers, Nucleotide, Base Sequence, Biosensing Techniques, Dopamine, Indium, Limit of Detection, Nanotechnology, Printing, Transistors, Electronic, biosensor, field-effect transistor, chemical lift-off lithography, metal-oxide semiconductor, sol gel chemistry, aptamer, neurotransmitter, dopamine, nanotechnology, nanofabrication, sensor, sol−gel chemistry, Nanoscience & Nanotechnology
Abstract

We demonstrate straightforward fabrication of highly sensitive biosensor arrays based on field-effect transistors, using an efficient high-throughput, large-area patterning process. Chemical lift-off lithography is used to construct field-effect transistor arrays with high spatial precision suitable for the fabrication of both micrometer- and nanometer-scale devices. Sol-gel processing is used to deposit ultrathin (∼4 nm) In2O3 films as semiconducting channel layers. The aqueous sol-gel process produces uniform In2O3 coatings with thicknesses of a few nanometers over large areas through simple spin-coating, and only low-temperature thermal annealing of the coatings is required. The ultrathin In2O3 enables construction of highly sensitive and selective biosensors through immobilization of specific aptamers to the channel surface; the ability to detect subnanomolar concentrations of dopamine is demonstrated.

Published
2015

20. CTA contributions to the 33rd International Cosmic Ray Conference (ICRC2013)

Author

Consortium, The CTA, Abril, O., Acharya, B. S., Actis, M., Agnetta, G., Aguilar, J. A., Aharonian, F., Ajello, M., Akhperjanian, A., Alcubierre, M., Aleksic, J., Alfaro, R., Aliu, E., Allafort, A. J., Allan, D., Allekotte, I., Aloisio, R., Amato, E., Ambrosi, G., Ambrosio, M., Anderson, J., Angüner, E. O., Antonelli, L. A., Antonuccio, V., Antonucci, M., Antoranz, P., Aravantinos, A., Argan, A., Arlen, T., Aramo, C., Armstrong, T., Arnaldi, H., Arrabito, L., Asano, K., Ashton, T., Asorey, H. G., Aune, T., Awane, Y., Baba, H., Babic, A., Baby, N., Bähr, J., Bais, A., Baixeras, C., Bajtlik, S., Balbo, M., Balis, D., Balkowski, C., Ballet, J., Bamba, A., Bandiera, R., Barber, A., Barbier, C., Barceló, M., Barnacka, A., Barnstedt, J., de Almeida, U. Barres, Barrio, J. A., Basili, A., Basso, S., Bastieri, D., Bauer, C., Baushev, A., Becciani, U., Becerra, J., Becherini, Y., Bechtol, K. C., Tjus, J. Becker, Beckmann, V., Bednarek, W., Behera, B., Belluso, M., Benbow, W., Berdugo, J., Berge, D., Berger, K., Bernard, F., Bernardino, T., Bernlöhr, K., Bertucci, B., Bhat, N., Bhattacharyya, S., Biasuzzi, B., Bigongiari, C., Biland, A., Billotta, S., Bird, T., Birsin, E., Bissaldi, E., Biteau, J., Bitossi, M., Blake, S., Bigas, O. Blanch, Blasi, P., Bobkov, A., Boccone, V., Böttcher, M., Bogacz, L., Bogart, J., Bogdan, M., Boisson, C., Gargallo, J. Boix, Bolmont, J., Bonanno, G., Bonardi, A., Bonev, T., Bonifacio, P., Bonnoli, G., Bordas, P., Borgland, A., Borkowski, J., Bose, R., Botner, O., Bottani, A., Bouchet, L., Bourgeat, M., Boutonnet, C., Bouvier, A., Brau-Nogué, S., Braun, I., Bretz, T., Briggs, M., Brigida, M., Bringmann, T., Britto, R., Brook, P., Brun, P., Brunetti, L., Bruno, P., Bucciantini, N., Buanes, T., Buckley, J., Bühler, R., Bugaev, V., Bulgarelli, A., Bulik, T., Busetto, G., Buson, S., Byrum, K., Cailles, M., Cameron, R., Camprecios, J., Canestrari, R., Cantu, S., Capalbi, M., Caraveo, P., Carmona, E., Carosi, A., Carosi, R., Carr, J., Carter, J., Carton, P. -H., Caruso, R., Casanova, S., Cascone, E., Casiraghi, M., Castellina, A., Catalano, O., Cavazzani, S., Cazaux, S., Cerchiara, P., Cerruti, M., Chabanne, E., Chadwick, P., Champion, C., Chaves, R., Cheimets, P., Chen, A., Chiang, J., Chiappetti, L., Chikawa, M., Chitnis, V. R., Chollet, F., Christof, A., Chudoba, J., Cieślar, M., Cillis, A., Cilmo, M., Codino, A., Cohen-Tanugi, J., Colafrancesco, S., Colin, P., Colome, J., Colonges, S., Compin, M., Conconi, P., Conforti, V., Connaughton, V., Conrad, J., Contreras, J. L., Coppi, P., Coridian, J., Corona, P., Corti, D., Cortina, J., Cossio, L., Costa, A., Costantini, H., Cotter, G., Courty, B., Couturier, S., Covino, S., Crimi, G., Criswell, S. J., Croston, J., Cusumano, G., Dafonseca, M., Dale, O., Daniel, M., Darling, J., Davids, I., Dazzi, F., de Angelis, A., De Caprio, V., De Frondat, F., Pino, E. M. de Gouveia Dal, de la Calle, I., De La Vega, G. A., Lopez, R. de los Reyes, de Lotto, B., De Luca, A., de Naurois, M., de Oliveira, Y., Wilhelmi, E. de Oña, de Palma, F., de Souza, V., Decerprit, G., Decock, G., Deil, C., Delagnes, E., Deleglise, G., Delgado, C., della Volpe, D., Demange, P., Depaola, G., Dettlaff, A., Di Girolamo, T., Di Giulio, C., Di Paola, A., Di Pierro, F., di Sciascio, G., Díaz, C., Dick, J., Dickherber, R., Dickinson, H., Diez-Blanco, V., Digel, S., Dimitrov, D., Disset, G., Djannati-Ataï, A., Doert, M., Dohmke, M., Domainko, W., Prester, D. Dominis, Donat, A., Dorner, D., Doro, M., Dournaux, J. -L., Drake, G., Dravins, D., Drury, L., Dubois, F., Dubois, R., Dubus, G., Dufour, C., Dumas, D., Dumm, J., Durand, D., Dwarkadas, V., Dyks, J., Dyrda, M., Ebr, J., Edy, E., Egberts, K., Eger, P., Einecke, S., Eleftheriadis, C., Elles, S., Emmanoulopoulos, D., Engelhaupt, D., Enomoto, R., Ernenwein, J. -P., Errando, M., Etchegoyen, A., Evans, P. A., Falcone, A., Faltenbacher, A., Fantinel, D., Farakos, K., Farnier, C., Farrell, E., Fasola, G., Favill, B. W., Fede, E., Federici, S., Fegan, S., Feinstein, F., Ferenc, D., Ferrando, P., Fesquet, M., Fetfatzis, P., Fiasson, A., Fillin-Martino, E., Fink, D., Finley, C., Finley, J. P., Fiorini, M., Curcoll, R. Firpo, Flandrini, E., Fleischhack, H., Flores, H., Florin, D., Focke, W., Föhr, C., Fokitis, E., Font, L., Fontaine, G., Fornasa, M., Förster, A., Fortson, L., Fouque, N., Franckowiak, A., Franco, F. J., Frankowski, A., Fransson, C., Fraser, G. W., Frei, R., Fresnillo, L., Fruck, C., Fugazza, D., Fujita, Y., Fukazawa, Y., Fukui, Y., Funk, S., Gäbele, W., Gabici, S., Gabriele, R., Gadola, A., Galante, N., Gall, D., Gallant, Y., Gámez-García, J., Garczarczyk, M., García, B., López, R. 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Moralejo, Mordalska, M., Morello, C., Mori, K., Morlino, G., Morselli, A., Mottez, F., Moudden, Y., Moulin, E., Mrusek, I., Mukherjee, R., Munar-Adrover, P., Muraishi, H., Murase, K., Murphy, A. StJ., Nagataki, S., Naito, T., Nakajima, D., Nakamori, T., Nakayama, K., Naumann, C., Naumann, D., Naumann-Godo, M., Nayman, P., Nedbal, D., Neise, D., Nellen, L., Neronov, A., Neustroev, V., Neyroud, N., Nicastro, L., Nicolau-Kukliński, J., Niedźwiecki, A., Niemiec, J., Nieto, D., Nikolaidis, A., Nishijima, K., Nishikawa, K. -I., Noda, K., Nolan, S., Northrop, R., Nosek, D., Nowak, N., Nozato, A., Oakes, L., O'Brien, P. T., Ohira, Y., Ohishi, M., Ohm, S., Ohoka, H., Okuda, T., Okumura, A., Olive, J. -F., Ong, R. A., Orito, R., Orr, M., Osborne, J. P., Ostrowski, M., Otero, L. A., Otte, N., Ovcharov, E., Oya, I., Ozieblo, A., Padilla, L., Pagano, I., Paiano, S., Paillot, D., Paizis, A., Palanque, S., Palatka, M., Pallota, J., Palatiello, M., Panagiotidis, K., Panazol, J. -L., Paneque, D., Panter, M., Panzera, M. R., Paoletti, R., Papayannis, A., Papyan, G., Paredes, J. M., Pareschi, G., Parraud, J. -M., Parsons, D., Pauletta, G., Arribas, M. Paz, Pech, M., Pedaletti, G., Pelassa, V., Pelat, D., Perez, M. d. C., Persic, M., Petrucci, P. -O., Peyaud, B., Pichel, A., Pieloth, D., Pierre, E., Pita, S., Pivato, G., Pizzolato, F., Platino, M., Platos, Ł., Platzer, R., Podkladkin, S., Pogosyan, L., Pohl, M., Pojmanski, G., Ponz, J. D., Potter, W., Poutanen, J., Prandini, E., Prast, J., Preece, R., Profeti, F., Prokoph, H., Prouza, M., Proyetti, M., Puerto-Giménez, I., Pühlhofer, G., Puljak, I., Punch, M., Pyzioł, R., Quel, E. J., Quesada, J., Quinn, J., Quirrenbach, A., Racero, E., Rainò, S., Rajda, P. J., Rameez, M., Ramon, P., Rando, R., Rannot, R. C., Rataj, M., Raue, M., Ravignani, D., Reardon, P., Reimann, O., Reimer, A., Reimer, O., Reitberger, K., Renaud, M., Renner, S., Reville, B., Rhode, W., Ribó, M., Ribordy, M., Richards, G., Richer, M. G., Rico, J., Ridky, J., Rieger, F., Ringegni, P., Ripken, J., Ristori, P. R., Rivière, A., Rivoire, S., Rob, L., Rodeghiero, G., Roeser, U., Rohlfs, R., Rojas, G., Romano, P., Romaszkan, W., Romero, G. E., Rosen, S. R., Lees, S. Rosier, Ross, D., Rouaix, G., Rousselle, J., Rousselle, S., Rovero, A. C., Roy, F., Royer, S., Rudak, B., Rulten, C., Rupiński, M., Russo, F., Ryde, F., Saavedra, O., Sacco, B., Saemann, E. O., Saggion, A., Sahakian, V., Saito, K., Saito, T., Saito, Y., Sakaki, N., Sakonaka, R., Salini, A., Sanchez, F., Sanchez-Conde, M., Sandoval, A., Sandaker, H., Sant'Ambrogio, E., Santangelo, A., Santos, E. M., Sanuy, A., Sapozhnikov, L., Sarkar, S., Sartore, N., Sasaki, H., Satalecka, K., Sawada, M., Scalzotto, V., Scapin, V., Scarcioffolo, M., Schafer, J., Schanz, T., Schlenstedt, S., Schlickeiser, R., Schmidt, T., Schmoll, J., Schovanek, P., Schroedter, M., Schubert, A., Schultz, C., Schultze, J., Schulz, A., Schure, K., Schussler, F., Schwab, T., Schwanke, U., Schwarz, J., Schwarzburg, S., Schweizer, T., Schwemmer, S., Schwendicke, U., Schwerdt, C., Segreto, A., Seiradakis, J. -H., Sembroski, G. H., Servillat, M., Seweryn, K., Sharma, M., Shayduk, M., Shellard, R. C., Shi, J., Shibata, T., Shibuya, A., Shore, S., Shum, E., Sideras-Haddad, E., Sidoli, L., Sidz, M., Sieiro, J., Sikora, M., Silk, J., Sillanpää, A., Singh, B. B., Sironi, G., Sitarek, J., Skole, C., Smareglia, R., Smith, A., Smith, D., Smith, J., Smith, N., Sobczyńska, D., Sol, H., Sottile, G., Sowiński, M., Spanier, F., Spiga, D., Spyrou, S., Stamatescu, V., Stamerra, A., Starling, R. L. C., Stawarz, Ł., Steenkamp, R., Stegmann, C., Steiner, S., Stella, C., Stergioulas, N., Sternberger, R., Sterzel, M., Stinzing, F., Stodulski, M., Stolarczyk, Th., Straumann, U., Strazzeri, E., Stringhetti, L., Suarez, A., Suchenek, M., Sugawara, R., Sulanke, K. -H., Sun, S., Supanitsky, A. D., Suric, T., Sutcliffe, P., Sykes, J. M., Szanecki, M., Szepieniec, T., Szostek, A., Tagliaferri, G., Tajima, H., Takahashi, H., Takahashi, K., Takalo, L., Takami, H., Talbot, G., Tammi, J., Tanaka, M., Tanaka, S., Tasan, J., Tavani, M., Tavernet, J. -P., Tejedor, L. A., Telezhinsky, I., Temnikov, P., Tenzer, C., Terada, Y., Terrier, R., Teshima, M., Testa, V., Tezier, D., Thayer, J., Thuermann, D., Tibaldo, L., Tibolla, O., Tiengo, A., Timpanaro, M. C., Tluczykont, M., Peixoto, C. J. Todero, Tokanai, F., Tokarz, M., Toma, K., Tonachini, A., Torii, K., Tornikoski, M., Torres, D. F., Torres, M., Toscano, S., Toso, G., Tosti, G., Totani, T., Toussenel, F., Tovmassian, G., Travnicek, P., Treves, A., Trifoglio, M., Troyano, I., Tsinganos, K., Ueno, H., Umana, G., Umehara, K., Upadhya, S. S., Usher, T., Uslenghi, M., Vagnetti, F., Valdes-Galicia, J. F., Vallania, P., Vallejo, G., van Driel, W., van Eldik, C., Vandenbrouke, J., Vanderwalt, J., Vankov, H., Vasileiadis, G., Vassiliev, V., Veberic, D., Vegas, I., Vercellone, S., Vergani, S., Verzi, V., Vettolani, G. P., Veyssière, C., Vialle, J. P., Viana, A., Videla, M., Vigorito, C., Vincent, P., Vincent, S., Vink, J., Vlahakis, N., Vlahos, L., Vogler, P., Voisin, V., Vollhardt, A., von Gunten, H. -P., Vorobiov, S., Vuerli, C., Waegebaert, V., Wagner, R., Wagner, R. G., Wagner, S., Wakely, S. P., Walter, R., Walther, T., Warda, K., Warwick, R. S., Wawer, P., Wawrzaszek, R., Webb, N., Wegner, P., Weinstein, A., Weitzel, Q., Welsing, R., Werner, M., Wetteskind, H., White, R. J., Wierzcholska, A., Wiesand, S., Wilhelm, A., Wilkinson, M. I., Williams, D. A., Willingale, R., Winde, M., Winiarski, K., Wischnewski, R., Wiśniewski, Ł., Wojcik, P., Wood, M., Wörnlein, A., Xiong, Q., Yadav, K. K., Yamamoto, H., Yamamoto, T., Yamazaki, R., Yanagita, S., Yebras, J. M., Yelos, D., Yoshida, A., Yoshida, T., Yoshikoshi, T., Yu, P., Zabalza, V., Zacharias, M., Zajczyk, A., Zampieri, L., Zanin, R., Zdziarski, A., Zech, A., Zhao, A., Zhou, X., Zietara, K., Ziolkowski, J., Ziółkowski, P., Zitelli, V., Zurbach, C., and Zychowski, P.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment
Abstract

Compilation of CTA contributions to the proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), which took place in 2-9 July, 2013, in Rio de Janeiro, Brazil, Comment: Index of CTA conference proceedings at the ICRC2013, Rio de Janeiro (Brazil). v1: placeholder with no arXiv links yet, to be replaced once individual contributions have been all submitted. v2: final with arXiv links to all CTA contributions and full author list

Published
2013

21. Discovery of TeV Gamma-ray Emission Toward Supernova Remnant SNR G78.2+2.1

Author

Aliu, E., Archambault, S., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bird, R., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Dumm, J., Dwarkadas, V. V., Errando, M., Falcone, A., Federici, S., Feng, Q., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gillanders, G. H., Godambe, S., Gotthelf, E. V., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lee, K., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., Millis, J., Moriarty, P., Mukherjee, R., Nelson, T., de Bhróithe, A. O'Faoláin, Ong, R. A., Orr, M., Otte, A. N., Pandel, D., Park, N., Perkins, J. S., Pohl, M., Popkow, A., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Skole, C., Telezhinsky, I., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Welsing, R., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report the discovery of an unidentified, extended source of very-high-energy (VHE) gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hours of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic extent of 0.23^{\circ} \pm 0.03^{\circ} (stat)+0.04^{\circ}_{-0.02}^{\circ}(sys) and its spectrum is well-characterized by a differential power law (dN/dE = N_0 \times (E/TeV)^{-\Gamma}) with a photon index of {\Gamma} = 2.37 \pm 0.14 (stat) \pm 0.20 (sys) and a flux normalization of N0 = 1.5 \pm 0.2 (stat) \pm 0.4(sys) \times 10^-12 ph TeV^{-1} cm^{-2} s^{-1}. This yields an integral flux of 5.2 \pm 0.8 (stat) \pm 1.4 (sys) \times 10^-12 ph cm^{-2} s^{-1} above 320 GeV, corresponding to 3.7% of the Crab Nebula flux. We consider the relationship of the TeV gamma-ray emission with the GeV gamma-ray emission seen from SNR G78.2+2.1 as well as that seen from a nearby cocoon of freshly accelerated cosmic rays. Multiple scenarios are considered as possible origins for the TeV gamma-ray emission, including hadronic particle acceleration at the supernova remnant shock., Comment: 18 pages, 5 figures, accepted for publication in ApJ

Published
2013
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22. VERITAS Observations of Six Bright, Hard-Spectrum Fermi-LAT Blazars

Author

Aliu, E., Archambault, S., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bottcher, M., Bouvier, A., Buckley, J. H., Bugaev, V., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Dumm, J., Errando, M., Falcone, A., Federici, S., Feng, Q., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Holder, J., Huan, H., Kaaret, P., Karlsson, N., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lee, K., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nelson, T., de Bhroithe, A. O'Faolain, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Saxon, D. B., Sembroski, G. H., Staszak, D., Telezhinsky, I., Tesic, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Weekes, T. C., Weinstein, A., Welsing, R., Williams, D. A., Zitzer, B., Fortin, P., Horan, D., Fumagalli, M., Kaplan, K., and Prochaska, J. X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on VERITAS very-high-energy (VHE; E>100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band, taking gamma-ray absorption by the extragalactic background light into account. This allowed the selection of six bright, hard-spectrum blazars that were good candidate TeV emitters. Spectroscopic redshift measurements were attempted with the Keck Telescope for the targets without Sloan Digital Sky Survey (SDSS) spectroscopic data. No VHE emission is detected during the observations of the six sources described here. Corresponding TeV upper limits are presented, along with contemporaneous Fermi observations and non-concurrent Swift UVOT and XRT data. The blazar broadband spectral energy distributions (SEDs) are assembled and modeled with a single-zone synchrotron self-Compton model. The SED built for each of the six blazars show a synchrotron peak bordering between the intermediate- and high-spectrum-peak classifications, with four of the six resulting in particle-dominated emission regions.

Published
2012
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23. Search for a correlation between very-high-energy gamma rays and giant radio pulses in the Crab pulsar

Author

Aliu, E., Archambault, S., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Buckley, J. H., Bugaev, V., Byrum, K., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Dumm, J., Falcone, A., Federici, S., Feng, Q., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Humensky, T. B., Kaaret, P., Karlsson, N., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Lee, K., Lyutikov, M., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nelson, T., de Bhroithe, A. O'Faolain, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Saxon, D. B., Schroedter, M., Sembroski, G. H., Senturk, G. D., Smith, A. W., Staszak, D., Telezhinsky, I., Tesic, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Varlotta, A., Vincent, S., Vivier, M., Wagner, R. G., Wakely, S. P., Weekes, T. C., Weinstein, A., Welsing, R., Williams, D. A., Zitzer, B., and Kondratiev, V.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present the results of a joint observational campaign between the Green Bank radio telescope and the VERITAS gamma-ray telescope, which searched for a correlation between the emission of very-high-energy (VHE) gamma rays ($E_{\gamma} >$ 150 GeV) and Giant Radio Pulses (GRPs) from the Crab pulsar at 8.9 GHz. A total of 15366 GRPs were recorded during 11.6 hours of simultaneous observations, which were made across four nights in December 2008 and in November and December 2009. We searched for an enhancement of the pulsed gamma-ray emission within time windows placed around the arrival time of the GRP events. In total, 8 different time windows with durations ranging from 0.033 ms to 72 s were positioned at three different locations relative to the GRP to search for enhanced gamma-ray emission which lagged, led, or was concurrent with, the GRP event. Further, we performed separate searches on main pulse GRPs and interpulse GRPs and on the most energetic GRPs in our data sample. No significant enhancement of pulsed VHE emission was found in any of the preformed searches. We set upper limits of 5-10 times the average VHE flux of the Crab pulsar on the flux simultaneous with interpulse GRPs on single-rotation-period time scales. On $\sim$8-second time scales around interpulse GRPs, we set an upper limit of 2-3 times the average VHE flux. Within the framework of recent models for pulsed VHE emission from the Crab pulsar, the expected VHE-GRP emission correlations are below the derived limits., Comment: 12 pages, 12 figures, To appear in The Astrophysical Journal

Published
2012
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24. Constraints on Cosmic Rays, Magnetic Fields, and Dark Matter from Gamma-Ray Observations of the Coma Cluster of Galaxies with VERITAS and Fermi

Author

Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Dumm, J., Falcone, A., Federici, S., Feng, Q., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Holder, J., Huan, H., Hughes, G., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lee, K., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nelson, T., de Bhróithe, A. O'Faoláin, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Skole, C., Smith, A. W., Telezhinsky, I., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Varlotta, A., Vivier, M., Wakely, S. P., Ward, J. E., Weinstein, A., Welsing, R., Williams, D. A., Zitzer, B., Pfrommer, C., and Pinzke, A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated, suggesting that clusters may also be sources of very high-energy (VHE; E>100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cherenkov telescopes, with complementing Fermi-LAT observations at GeV energies. No significant gamma-ray emission from the Coma cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order of (2-5)*10^-8\ ph. m^-2 s^-1 (VERITAS, >220 GeV} and ~2*10^-6 ph. m^-2 s^-1 (Fermi, 1-3 GeV), respectively. We use the gamma-ray upper limits to constrain CRs and magnetic fields in Coma. Using an analytical approach, the CR-to-thermal pressure ratio is constrained to be < 16% from VERITAS data and < 1.7% from Fermi data (averaged within the virial radius). These upper limits are starting to constrain the CR physics in self-consistent cosmological cluster simulations and cap the maximum CR acceleration efficiency at structure formation shocks to be <50%. Assuming that the radio-emitting electrons of the Coma halo result from hadronic CR interactions, the observations imply a lower limit on the central magnetic field in Coma of (2 - 5.5) muG, depending on the radial magnetic-field profile and on the gamma-ray spectral index. Since these values are below those inferred by Faraday rotation measurements in Coma (for most of the parameter space), this {renders} the hadronic model a very plausible explanation of the Coma radio halo. Finally, since galaxy clusters are dark-matter (DM) dominated, the VERITAS upper limits have been used to place constraints on the thermally-averaged product of the total self-annihilation cross section and the relative velocity of the DM particles, <\sigma v>. (abr.), Comment: ApJ in press

Published
2012
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25. Multiwavelength observations of the AGN 1ES 0414+009 with VERITAS, Fermi-LAT, Swift-XRT, and MDM

Author

Aliu, E., Archambault, S., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bottcher, M., Bouvier, A., Bugaev, V., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Dumm, J., Errando, M., Falcone, A., Federici, S., Feng, Q., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Huan, H., Hughes, G., Hui, C. M., Imran, A., Jameil, O., Kaaret, P., Karlsson, N., Kertzman, M., Kerr, J., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lee, K., Madhavan, A. S., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nelson, T., de Bhroithe, A. O'Faolain, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pohl, M., Quinn, J., Ragan, K., Reynolds, P. T., Roache, E., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Senturk, G. D., Smith, A. W., Staszak, D., Stroh, M., Telezhinsky, I., Tesic, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Varlotta, A., Vassiliev, V. V., Vivier, M., Wakely, S. P., Ward, J. E., Weinstein, A., Welsing, R., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between January 2008 and February 2011, resulting in 56.2 hours of good quality pointed observations. These observations resulted in a detection of 822 events from the source corresponding to a statistical significance of 6.4 standard deviations (6.4 sigma) above the background. The source flux, showing no evidence for variability, is measured as 5.2 +/- 1.1_stat +/- 2.6_sys * 10^-12 photons cm^-2 s^-1 above 200 GeV, equivalent to approximately 2% of the Crab Nebula flux above this energy. The differential photon spectrum from 230 GeV to 850 GeV is well fit by a power law with an photon index of Gamma 3.4 +/- 0.5_stat +/- 0.3_sys and a flux normalization of 1.6 +/- 0.3_stat +/- 0.8_sys * 10^-11 photons cm^-2 s^-1 at 300 GeV. We also present multiwavelength results taken in the optical (MDM), X-ray (Swift-XRT), and GeV (Fermi-LAT) bands and use these results to construct a broadband spectral energy distribution (SED). Modeling of this SED indicates that homogenous one-zone leptonic scenarios are not adequate to describe emission from the system, with a lepto-hadronic model providing a better fit to the data., Comment: Accepted for publication in The Astrophysical Journal

Published
2012
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26. VERITAS Observations of the Nova in V407 Cygni

Author

Aliu, E., Archambault, S., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Decerprit, G., Dickherber, R., Duke, C., Dumm, J., Dwarkadas, V. V., Errando, M., Falcone, A., Feng, Q., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lee, K., Maier, G., Majumdar, P., McArthur, S., McCann, A., Millis, J., Moriarty, P., Mukherjee, R., Nuñez, P. D, Ong, R. A., Orr, M., Otte, A. N., Pandel, D., Park, N., Perkins, J. S., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Skole, C., Smith, A. W., Staszak, D., Telezhinsky, I., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Welsing, R., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies
Abstract

We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1-10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles, due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 \times 10^(-12) erg cm^(-2) s^(-1) (at the 95% confidence level). When considered jointly with data from Fermi-LAT, this result places limits on the acceleration of very high energy particles in the nova., Comment: 17 pages, 4 figures, accepted for publication in ApJ

Published
2012
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27. Discovery of High-energy and Very High Energy Gamma-ray Emission from the Blazar RBS 0413

Author

VERITAS Collaboration, Aliu, E., Archambault, S., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Boettcher, M., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Coppi, P., Cui, W., Decerprit, G., Dickherber, R., Dumm, J., Errando, M., Falcone, A., Feng, Q., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Hawkins, K., Holder, J., Huan, H., Hughes, G., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lee, K., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Ong, R. A., Orr, M., Otte, A. N., Palma, N., Park, N., Perkins, J. S., Pichel, A., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Senturk, G. D., Smith, A. W., Staszak, D., Telezhinsky, I., Tesic, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Varlotta, A., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., Zitzer, B., Fortin, P., and Horan, D.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on the discovery of high-energy (HE; E > 0.1 GeV) and very high-energy (VHE; E > 100 GeV) gamma-ray emission from the high-frequency-peaked BL Lac object RBS 0413. VERITAS, a ground-based gamma-ray observatory, detected VHE gamma rays from RBS 0413 with a statistical significance of 5.5 standard deviations (sigma) and a gamma-ray flux of (1.5 \pm 0.6stat \pm 0.7syst) \times 10^(-8) photons m^(-2) s^(-1) (\sim 1% of the Crab Nebula flux) above 250 GeV. The observed spectrum can be described by a power law with a photon index of 3.18 \pm 0.68stat \pm 0.30syst. Contemporaneous observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope detected HE gamma rays from RBS 0413 with a statistical significance of more than 9 sigma, a power-law photon index of 1.57 \pm 0.12stat +0.11sys -0.12sys and a gamma-ray flux between 300 MeV and 300 GeV of (1.64 \pm 0.43stat +0.31sys -0.22sys) \times 10^(-5) photons m^(-2) s^(-1). We present the results from Fermi-LAT and VERITAS, including a spectral energy distribution modeling of the gamma-ray, quasi-simultaneous X-ray (Swift-XRT), ultraviolet (Swift-UVOT) and R-band optical (MDM) data. We find that, if conditions close to equipartition are required, both the combined synchrotron self-Compton/external-Compton and the lepto-hadronic models are preferred over a pure synchrotron self-Compton model., Comment: 14 pages, 3 figures, accepted to ApJ, corresponding author: G. D. Senturk

Published
2012
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28. VERITAS Deep Observations of the Dwarf Spheroidal Galaxy Segue 1

Author

Aliu, E., Archambault, S., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Christiansen, J. L., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Decerprit, G., Dickherber, R., Dumm, J., Errando, M., Falcone, A., Feng, Q., Ferrer, F., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lee, K., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Senturk, G. D., Skole, C., Smith, A. W., Staszak, D., Telezhinsky, I., Tesic, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wagner, R. G., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, High Energy Physics - Experiment
Abstract

The VERITAS array of Cherenkov telescopes has carried out a deep observational program on the nearby dwarf spheroidal galaxy Segue 1. We report on the results of nearly 48 hours of good quality selected data, taken between January 2010 and May 2011. No significant $\gamma$-ray emission is detected at the nominal position of Segue 1, and upper limits on the integrated flux are derived. According to recent studies, Segue 1 is the most dark matter-dominated dwarf spheroidal galaxy currently known. We derive stringent bounds on various annihilating and decaying dark matter particle models. The upper limits on the velocity-weighted annihilation cross-section are $\mathrm{<\sigma v >^{95% CL} \lesssim 10^{-23} cm^{3} s^{-1}}$, improving our limits from previous observations of dwarf spheroidal galaxies by at least a factor of two for dark matter particle masses $\mathrm{m_{\chi}\gtrsim 300 GeV}$. The lower limits on the decay lifetime are at the level of $\mathrm{\tau^{95% CL} \gtrsim 10^{24} s}$. Finally, we address the interpretation of the cosmic ray lepton anomalies measured by ATIC and PAMELA in terms of dark matter annihilation, and show that the VERITAS observations of Segue 1 disfavor such a scenario., Comment: Added recently published erratum at the end of the original article

Published
2012
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29. VERITAS Observations of day-scale flaring of M87 in 2010 April

Author

Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nunez, P. D, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Skole, C., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of the radio galaxy M87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +- 0.16) X 10^{-11} cm^{-2} s^{-1} at energies above 350GeV. In 2010 April, VERITAS detected a flare from M87 with peak flux of (2.71 +- 0.68) X 10^{-11} cm^{-2} s^{-1} for E>350GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90^{+0.22}_{-0.15} days. The shortest detected exponential rise time is three times as long, at 2.87^{+1.65}_{-0.99} days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 +- 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M87 and the constraints they provide on the physical size of the emitting region., Comment: Accepted for publication in ApJ; 17 pages, 5 figures; Corresponding author: C. M. Hui

Published
2011
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30. The 2010 very high energy gamma-ray flare & 10 years of multi-wavelength observations of M 87

Author

Collaboration, The H. E. S. S., Abramowski, A., Acero, F., Aharonian, F., Akhperjanian, A. G., Anton, G., Balzer, A., Barnacka, A., de Almeida, U. Barres, Becherini, Y., Becker, J., Behera, B., Bernlöhr, K., Birsin, E., Biteau, J., Bochow, A., Boisson, C., Bolmont, J., Bordas, P., Brucker, J., Brun, F., Brun, P., Bulik, T., Büsching, I., Carrigan, S., Casanova, S., Cerruti, M., Chadwick, P. M., Charbonnier, A., Chaves, R. C. G., Cheesebrough, A., Clapson, A. C., Coignet, G., Cologna, G., Conrad, J., Dalton, M., Daniel, M. K., Davids, I. D., Degrange, B., Deil, C., Dickinson, H. J., Djannati-Ataï, A., Domainko, W., Drury, L. O'C., Dubus, G., Dutson, K., Dyks, J., Dyrda, M., Egberts, K., Eger, P., Espigat, P., Fallon, L., Farnier, C., Fegan, S., Feinstein, F., Fernandes, M. V., Fiasson, A., Fontaine, G., Förster, A., Füßling, M., Gallant, Y. A., Gast, H., Gérard, L., Gerbig, D., Giebels, B., Glicenstein, J. F., Glück, B., Goret, P., Göring, D., Häffner, S., Hague, J. D., Hampf, D., Hauser, M., Heinz, S., Heinzelmann, G., Henri, G., Hermann, G., Hinton, J. A., Hoffmann, A., Hofmann, W., Hofverberg, P., Holler, M., Horns, D., Jacholkowska, A., de Jager, O. C., Jahn, C., Jamrozy, M., Jung, I., Kastendieck, M. A., Katarzyński, K., Katz, U., Kaufmann, S., Keogh, D., Khangulyan, D., Khélifi, B., Klochkov, D., Kluźniak, W., Kneiske, T., Komin, Nu., Kosack, K., Kossakowski, R., Laffon, H., Lamanna, G., Lennarz, D., Lohse, T., Lopatin, A., Lu, C. -C., Marandon, V., Marcowith, A., Masbou, J., Maurin, D., Maxted, N., Mayer, M., McComb, T. J. L., Medina, M. C., Méhault, J., Moderski, R., Moulin, E., Naumann, C. L., Naumann-Godo, M., de Naurois, M., Nedbal, D., Nekrassov, D., Nguyen, N., Nicholas, B., Niemiec, J., Nolan, S. J., Ohm, S., Wilhelmi, E. de Oña, Opitz, B., Ostrowski, M., Oya, I., Panter, M., Arribas, M. Paz, Pedaletti, G., Pelletier, G., Petrucci, P. -O., Pita, S., Pühlhofer, G., Punch, M., Quirrenbach, A., Raue, M., Rayner, S. M., Reimer, A., Reimer, O., Renaud, M., Reyes, R. de los, Rieger, F., Ripken, J., Rob, L., Rosier-Lees, S., Rowell, G., Rudak, B., Rulten, C. B., Ruppel, J., Sahakian, V., Sanchez, D. A., Santangelo, A., Schlickeiser, R., Schöck, F. M., Schulz, A., Schwanke, U., Schwarzburg, S., Schwemmer, S., Sheidaei, F., Skilton, J. L., Sol, H., Spengler, G., Stawarz, Ł., Steenkamp, R., Stegmann, C., Stinzing, F., Stycz, K., Sushch, I., Szostek, A., Tavernet, J. -P., Terrier, R., Tluczykont, M., Valerius, K., van Eldik, C., Vasileiadis, G., Venter, C., Vialle, J. P., Viana, A., Vincent, P., Völk, H. J., Volpe, F., Vorobiov, S., Vorster, M., Wagner, S. J., Ward, M., White, R., Wierzcholska, A., Zacharias, M., Zajczyk, A., Zdziarski, A. A., Zech, A., Zechlin, H. -S., Collaboration, The MAGIC, Aleksić, J., Antonelli, L. A., Antoranz, P., Backes, M., Barrio, J. A., Bastieri, D., González, J. Becerra, Bednarek, W., Berdyugin, A., Berger, K., Bernardini, E., Biland, A., Blanch, O., Bock, R. K., Boller, A., Bonnoli, G., Tridon, D. Borla, Braun, I., Bretz, T., Cañellas, A., Carmona, E., Carosi, A., Colin, P., Colombo, E., Contreras, J. L., Cortina, J., Cossio, L., Covino, S., Dazzi, F., De Angelis, A., del Pozo, E. De Cea, De Lotto, B., Mendez, C. Delgado, Ortega, A. Diago, Doert, M., Domínguez, A., Prester, D. Dominis, Dorner, D., Doro, M., Elsaesser, D., Ferenc, D., Fonseca, M. V., Font, L., Fruck, C., López, R. J. García, Garczarczyk, M., Garrido, D., Giavitto, G., Godinović, N., Hadasch, D., Häfner, D., Herrero, A., Hildebrand, D., Höhne-Mönch, D., Hose, J., Hrupec, D., Huber, B., Jogler, T., Klepser, S., Krähenbühl, T., Krause, J., La Barbera, A., Lelas, D., Leonardo, E., Lindfors, E., Lombardi, S., López, M., Lorenz, E., Makariev, M., Maneva, G., Mankuzhiyil, N., Mannheim, K., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Meucci, M., Miranda, J. M., Mirzoyan, R., Miyamoto, H., Moldón, J., Moralejo, A., Munar, P., Nieto, D., Nilsson, K., Orito, R., Paneque, D., Paoletti, R., Pardo, S., Paredes, J. M., Partini, S., Pasanen, M., Pauss, F., Perez-Torres, M. A., Persic, M., Peruzzo, L., Pilia, M., Pochon, J., Prada, F., Moroni, P. G. Prada, Prandini, E., Puljak, I., Reichardt, I., Reinthal, R., Rhode, W., Ribó, M., Rico, J., Rügamer, S., Saggion, A., Saito, K., Saito, T. Y., Salvati, M., Satalecka, K., Scalzotto, V., Scapin, V., Schultz, C., Schweizer, T., Shayduk, M., Shore, S. N., Sillanpää, A., Sitarek, J., Sobczynska, D., Spanier, F., Spiro, S., Stamerra, A., Steinke, B., Storz, J., Strah, N., Surić, T., Takalo, L., Takami, H., Tavecchio, F., Temnikov, P., Terzić, T., Tescaro, D., Teshima, M., Thom, M., Tibolla, O., Torres, D. F., Treves, A., Vankov, H., Vogler, P., Wagner, R. M., Weitzel, Q., Zabalza, V., Zandanel, F., Zanin, R., Collaboration, The VERITAS, Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Ciupik, L., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hui, C. M., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., LeBohec, S., Maier, G., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nuñez, P. D., Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pohl, M., Prokoph, H., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Telezhinsky, I., Tešić, G., Theiling, M., Thibadeau, S., Varlotta, A., Vassiliev, V. V., Vivier, M., Wakely, S. P., Weekes, T. C., Williams, D. A., Zitzer, B., Cara, M., Casadio, C., Cheung, C. C., McConville, W., Davies, F., Doi, A., Giovannini, G., Giroletti, M., Hada, K., Hardee, P., Harris, D. E., Junor, W., Kino, M., Lee, N. P., Ly, C., Madrid, J., Massaro, F., Mundell, C. G., Nagai, H., Perlman, E. S., Steele, I. A., Walker, R. C., and Wood, D. L.

Subjects
Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

Abridged: The giant radio galaxy M 87 with its proximity, famous jet, and very massive black hole provides a unique opportunity to investigate the origin of very high energy (VHE; E>100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of super-massive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (~day), peak fluxes (Phi(>0.35 TeV) ~= (1-3) x 10^-11 ph cm^-2 s^-1), and VHE spectra. 43 GHz VLBA radio observations of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken ~3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core. The long-term (2001-2010) multi-wavelength light curve of M 87, spanning from radio to VHE and including data from HST, LT, VLA and EVN, is used to further investigate the origin of the VHE gamma-ray emission. No unique, common MWL signature of the three VHE flares has been identified., Comment: 19 pages, 5 figures; Corresponding authors: M. Raue, L. Stawarz, D. Mazin, P. Colin, C. M. Hui, M. Beilicke; Fig. 1 lightcurve data available online: http://www.desy.de/~mraue/m87/

Published
2011
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31. VERITAS Collaboration Contributions to the 32nd International Cosmic Ray Conference

Author

The VERITAS Collaboration, Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Böttcher, M., Bouvier, A., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Christiansen, J. L., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Dwarkadas, V. V., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lyutikov, M., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Nunez, P. D, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pizlo, F., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Rovero, A. C., Ruppel, J., Sadun, A. C., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Smith, A. W., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Compilation of papers contributed by the VERITAS Collaboration to the 32nd International Cosmic Ray Conference, held 11-18 August 2011 in Beijing, China., Comment: 1 html page. ICRC 2011, Beijing, China. A full list of authors and collaborating institutions can be found at http://veritas.sao.arizona.edu/conferences/authors?icrc2011

Published
2011

32. VERITAS: Status and Highlights

Author

Holder, J., Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Böttcher, M., Bouvier, A., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Christiansen, J. L., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Dwarkadas, V. V., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Khassen, Y., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lyutikov, M., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Nunez, P. D, Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pizlo, F., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Rovero, A. C., Ruppel, J., Sadun, A. C., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Smith, A. W., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

The VERITAS telescope array has been operating smoothly since 2007, and has detected gamma-ray emission above 100 GeV from 40 astrophysical sources. These include blazars, pulsar wind nebulae, supernova remnants, gamma-ray binary systems, a starburst galaxy, a radio galaxy, the Crab pulsar, and gamma-ray sources whose origin remains unidentified. In 2009, the array was reconfigured, greatly improving the sensitivity. We summarize the current status of the observatory, describe some of the scientific highlights since 2009, and outline plans for the future., Comment: Presented at the 32nd ICRC, Beijing, 2011

Published
2011
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33. Multiwavelength Observations of the Previously Unidentified Blazar RX J0648.7+1516

Author

Aliu, E., Aune, T., Beilicke, M., Benbow, W., Böttcher, M., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Cannon, A., Cesarini, A., Ciupik, L., Connolly, M. P., Cui, W., Decerprit, G., Dickherber, R., Duke, C., Errando, M., Falcone, A., Feng, Q., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Hivick, B., Holder, J., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Krawczynski, H., Krennrich, F., Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Nelson, T., Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Ruppel, J., Saxon, D. B., Sembroski, G. H., Skole, C., Smith, A. W., Staszak, D., Tesic, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Wakely, S. P., Weekes, T. C., Weinstein, A., Williams, D. A., Zitzer, B., Ciprini, S., Fumagalli, M., Kaplan, K., Paneque, D., and Prochaska, J. X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on the VERITAS discovery of very-high-energy (VHE) gamma- ray emission above 200 GeV from the high-frequency-peaked BL Lac object RXJ0648.7+1516 (GBJ0648+1516), associated with 1FGLJ0648.8+1516. The photon spectrum above 200 GeV is fit by a power law dN/dE = F0(E/E0)-{\Gamma} with a photon index {\Gamma} of 4.4 {\pm} 0.8stat {\pm}0.3syst and a flux normalization F0 of (2.3 {\pm}0.5stat {\pm} 1.2sys) {\times} 10-11 TeV-1cm-2s-1 with E0 = 300 GeV. No VHE vari- ability is detected during VERITAS observations of RXJ0648.7+1516 between 2010 March 4 and April 15. Following the VHE discovery, the optical identifica- tion and spectroscopic redshift were obtained using the Shane 3-m Telescope at the Lick Observatory, showing the unidentified object to be a BL Lac type with a redshift of z = 0.179. Broadband multiwavelength observations contemporaneous with the VERITAS exposure period can be used to sub-classify the blazar as a high-frequency-peaked BL Lac (HBL) object, including data from the MDM ob- servatory, Swift-UVOT and XRT, and continuous monitoring at photon energies above 1 GeV from the Fermi Large Area Telescope (LAT). We find that in the absence of undetected, high-energy rapid variability, the one-zone synchrotron self-Compton model (SSC) overproduces the high-energy gamma-ray emission measured by the Fermi-LAT over 2.3 years. The SED can be parameterized sat- isfactorily with an external-Compton or lepto-hadronic model, which have two and six additional free parameters, respectively, compared to the one-zone SSC model.

Published
2011
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34. Semi-Analytic Model for Intergalactic Gamma-Ray Cascades in Extragalactic Magnetic Fields

Author

Huan, H. and Weisgarber, T.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

Primary gamma rays emitted by extragalactic sources, such as blazars, will generate electromagnetic cascades in intergalactic space. These cascades proceed via electron-positron pair production and inverse Compton scattering on cosmic background radiation, mainly the cosmic microwave background (CMB) and extragalactic background light (EBL) fields. The existence of an extragalactic magnetic field (EGMF) could deflect electron-positron pair trajectories and scatter the cascade photons, possibly creating a halo around the source while suppressing the cascade flux collected by a detector. We develop a semi-analytic model for the cascade process and apply it to combine GeV-TeV data on high-frequency-peaked Bl Lacertae objects (HBLs) from the Fermi Large Area Telescope (LAT) and ground-based Cherenkov telescopes, comparing observation results with model predictions using a robust statistical framework. Lower limits with different confidence levels on the field strength of the EGMF derived from this procedure are discussed under various assumptions about the source livetime., Comment: 4 pages, 4 figures, proceeding for the 32nd International Cosmic Ray Conference

Published
2011

35. Detection of Pulsed Gamma Rays Above 100 GeV from the Crab Pulsar

Author

VERITAS Collaboration, Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Byrum, K., Cannon, A., Cesarini, A., Christiansen, J. L., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Duke, C., Errando, M., Falcone, A., Finley, J. P., Finnegan, G., Fortson, L., Furniss, A., Galante, N., Gall, D., Gibbs, K., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Guenette, R., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Imran, A., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Krawczynski, H., Krennrich, F., Lang, M. J., Lyutikov, M., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., McCutcheon, M., Moriarty, P., Mukherjee, R., Nuñez, P., Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pizlo, F., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Şentürk, G. D., Smith, A. W., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vassiliev, V. V., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weekes, T. C., Weinstein, A., Weisgarber, T., Williams, D. A., and Zitzer, B.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 Gigaelectronvolts (GeV) with the VERITAS array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 Megaelectronvolts (MeV) and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star., Comment: 17 pages, corresponding authors: Nepomuk Otte nepomuk.otte@gmail.com; Andrew McCann mccann@hep.physics.mcgill.ca; Martin Schroedter schroedter@veritas.sao.arizona.edu

Published
2011
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36. VERITAS Observations of the Unusual Extragalactic Transient Swift J164449.3+573451

Author

Aliu, E., Arlen, T., Aune, T., Beilicke, M., Benbow, W., Böttcher, M., Bouvier, A., Bradbury, S. M., Buckley, J. H., Bugaev, V., Cannon, A., Cesarini, A., Ciupik, L., Collins-Hughes, E., Connolly, M. P., Cui, W., Dickherber, R., Errando, M., Falcone, A., Finley, J. P., Fortson, L., Furniss, A., Galante, N., Gall, D., Gillanders, G. H., Godambe, S., Griffin, S., Grube, J., Gyuk, G., Hanna, D., Holder, J., Huan, H., Hughes, G., Hui, C. M., Humensky, T. B., Kaaret, P., Karlsson, N., Kertzman, M., Kieda, D., Krawczynski, H., Krennrich, F., Madhavan, A. S, Maier, G., Majumdar, P., McArthur, S., McCann, A., Moriarty, P., Mukherjee, R., Ong, R. A., Orr, M., Otte, A. N., Park, N., Perkins, J. S., Pichel, A., Pohl, M., Prokoph, H., Quinn, J., Ragan, K., Reyes, L. C., Reynolds, P. T., Roache, E., Rose, H. J., Ruppel, J., Saxon, D. B., Schroedter, M., Sembroski, G. H., Skole, C., Smith, A. W., Staszak, D., Tešić, G., Theiling, M., Thibadeau, S., Tsurusaki, K., Tyler, J., Varlotta, A., Vincent, S., Vivier, M., Wakely, S. P., Ward, J. E., Weinstein, A., Weisgarber, T., and Williams, D. A.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report on very-high-energy ($>$100 GeV) gamma-ray observations of Swift J164449.3+573451, an unusual transient object first detected by the {\it Swift} Observatory and later detected by multiple radio, optical and X-ray observatories. A total exposure of 28 hours was obtained on Swift J164449.3+573451 with VERITAS during 2011 March 28 -- April 15. We do not detect the source and place a differential upper limit on the emission at 500 GeV during these observations of $1.4 \times 10^{-12}$ erg cm$^{-2}$ s$^{-1}$ (99% confidence level). We also present time-resolved upper limits and use a flux limit averaged over the X-ray flaring period to constrain various emission scenarios that can accommodate both the radio-through-X-ray emission detected from the source and the lack of detection by VERITAS.

Published
2011
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37. A New Model for Gamma-Ray Cascades in Extragalactic Magnetic Fields

Author

Huan, H., Weisgarber, T., Arlen, T., and Wakely, S. P.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Extragalactic Astrophysics
Abstract

Very-high-energy (VHE, E \gtrsim 100 GeV) gamma rays emitted by extragalactic sources, such as blazars, initiate electromagnetic cascades in the intergalactic medium. The cascade photons arrive at the earth with angular and temporal distributions correlated with the extragalactic magnetic field (EGMF). We have developed a new semi-analytical model of the cascade properties which is more accurate than previous analytic approaches and faster than full Monte Carlo simulations. Within its range of applicability, our model can quickly generate cascade spectra for a variety of source emission models, EGMF strengths, and assumptions about the source livetime. In this Letter, we describe the properties of the model and demonstrate its utility by exploring the gamma-ray emission from the blazar RGB J0710+591. In particular, we predict, under various scenarios, the VHE and high-energy (HE, 100 MeV \lesssim E \lesssim 300 GeV) fluxes detectable with the VERITAS and Fermi Large Area Telescope (LAT) observatories. We then develop a systematic framework for comparing the predictions to published results, obtaining constraints on the EGMF strength. At a confidence level of 95%, we find the lower limit on the EGMF strength to be ~ 2 \times 10^{-16} Gauss if no limit is placed on the livetime of the source or ~ 3 \times 10^{-18} Gauss if the source livetime is limited to the past ~ 3 years during which Fermi observations have taken place., Comment: 5 pages, 5 figures, accepted for publication in Astrophysical Journal Letters

Published
2011
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38. Small-Molecule Arrays for Sorting G‑Protein-Coupled Receptors

Author

Liao, Wei-Ssu, Cao, Huan H, Cheunkar, Sarawut, Shuster, Mitchell J, Altieri, Stefanie C, Weiss, Paul S, and Andrews, Anne M

Subjects
Biotechnology, Bioengineering, Generic health relevance, Chemical Sciences, Engineering, Technology, Physical Chemistry
Abstract

Precise self-assembled monolayer chemistries and microfluidic technology are combined to create small-molecule biorecognition arrays. Small-molecule neurotransmitters or precursors are spatially encoded on monolayer-modified substrates. This platform enables multiplexed screening of G-protein-coupled receptors (GPCRs) from complex media via protein-ligand interactions. Preserving access to all epitopes of small molecules is critical for GPCR recognition. The ability to address multiple small molecules on solid substrates and to sort protein mixtures based on specific affinities is a critical step in creating biochips for proteomic applications. © 2013 American Chemical Society.

Published
2013

39. From the bottom up: dimensional control and characterization in molecular monolayers

Author

Claridge, Shelley A, Liao, Wei-Ssu, Thomas, John C, Zhao, Yuxi, Cao, Huan H, Cheunkar, Sarawut, Serino, Andrew C, Andrews, Anne M, and Weiss, Paul S

Subjects
Macromolecular and Materials Chemistry, Chemical Sciences, Graphite, Hydrogen Bonding, Nanostructures, Polymerization, Semiconductors, Surface Properties, General Chemistry, Chemical sciences, Engineering
Abstract

Self-assembled monolayers are a unique class of nanostructured materials, with properties determined by their molecular lattice structures, as well as the interfaces with their substrates and environments. As with other nanostructured materials, defects and dimensionality play important roles in the physical, chemical, and biological properties of the monolayers. In this review, we discuss monolayer structures ranging from surfaces (two-dimensional) down to single molecules (zero-dimensional), with a focus on applications of each type of structure, and on techniques that enable characterization of monolayer physical properties down to the single-molecule scale.

Published
2013

40. Mechanism of apoptosis in oral squamous cell carcinoma promoted by cardamonin through PI3K/AKT signaling pathway

Author

Yuehan Wu, Yapei Wang, Han Liu, Qiannan Hu, Yuqi Xie, Xiaoxu Nan, Huan He, and Ying Liu

Subjects
Oral squamous cell carcinoma, Network pharmacology, Cardamonin, PI3K/AKT, Apoptosis, Medicine, Science
Abstract

Abstract Currently, surgical resection remains the primary approach for treating oral squamous cell carcinoma (OSCC), with limited options for effective drug therapy. Cardamonin, a principal compound derived from Myristica fragrans of the Zingiberaceae family, has garnered attention for its potential to suppress the onset and progression of various malignancies encompassing breast cancer, hepatocellular carcinoma, and ovarian cancers. Nevertheless, the involvement of cardamonin in the treatment of OSCC and its underlying mechanisms are yet to be elucidated. This research explored the possible target of cardamonin in treating OSCC via network pharmacological analysis. Subsequently, this research investigated the impact of cardamonin on OSCC cells via in vitro experiments, revealing its capacity to impede the migration, proliferation, and invasion of OSCC cells. Additionally, western blotting analysis demonstrated that cardamonin facilitates apoptosis by regulating the PI3K/AKT pathway. The findings suggest that MMP9 and the PI3K/AKT signaling pathway may serve as the target and pathway of cardamonin in treating OSCC. To summarize, the research findings suggest that cardamonin may facilitate apoptosis in OSCC cells by inhibition of PI3K/AKT pathway activation. These outcomes offer a theoretical basis for the utilization of cardamonin as a natural drug for treating OSCC.

Published
2024
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41. A Fe-NC electrocatalyst boosted by trace bromide ions with high performance in proton exchange membrane fuel cells

Author

Shuhu Yin, Long Chen, Jian Yang, Xiaoyang Cheng, Hongbin Zeng, Yuhao Hong, Huan Huang, Xiaoxiao Kuai, Yangu Lin, Rui Huang, Yanxia Jiang, and Shigang Sun

Subjects
Science
Abstract

Abstract Replacement of expensive and rare platinum with metal–nitrogen–carbon catalysts for oxygen reduction reactions in proton exchange membrane fuel cells is hindered by their inferior activity. Herein, we report a highly active iron-nitrogen-carbon catalyst by optimizing the carbon structure and coordination environments of Fe-N4 sites. A critical high-temperature treatment with ammonium chloride and ammonium bromide not only enhances the intrinsic activity and density of Fe-N4 sites, but also introduces numerous defects, trace Br ions and creates mesopores in the carbon framework. Notably, surface Br ions significantly improve the interaction between the ionomer and catalyst particles, promoting ionomer infiltration and optimizing the O2 transport and charge transfer at triple-phase boundary. This catalyst delivers a high peak power density of 1.86 W cm−2 and 54 mA cm−2 at 0.9 ViR-free in a H2-O2 fuel cells at 80 °C. Our findings highlight the critical role of interface microenvironment regulation.

Published
2024
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42. Study on vertical hydraulic connection of aquifers based on hydro-chemical characteristics and pumping (discharging) water test

Author

Huan HUANG and Shuning DONG

Subjects
hydro-chemical characteristic, alternating cation adsorption, hydraulic correlation, pumping test, dewatering test, Mining engineering. Metallurgy, TN1-997
Abstract

The 3−1 coal in Xinjie Mining Area is buried deep, and the thick Zhiluo Formation and Zhidan Group aquifers are the main water-filled aquifers, and the hydraulic correlation between surface water and aquifers affects water inrush in the mine. Based on the hydro-chemical characteristics and the test of pumping (discharging) water, the vertical hydraulic connection of aquifer was carried out. The results of hydro-chemical tests and Piper chart show that the salinity of surface water, Zhidan Group and Zhiluo Formation aquifers increases gradually, and the hydro-chemical type changes from HCO3−Ca type to SO4−Na type. The analysis of Gibbs diagram and SOM model show that the ions in surface water mainly come from the weathering of carbonate rock and silicate rock, the ions in Zhidan Group aquifer and Zhiluo Formation aquifer mainly come from silicate rock and gypsum, and oxidation of metal sulfides is also exist in Zhiluo Formation aquifer. The controlling factor of hydro-chemical characteristics changes from water-rock interaction to evaporation concentration, the Zhidan Group aquifer and Zhiluo Formation aquifer have strong cation alternation. The Cl− index quantitatively indicates that the hydraulic correlation degree between surface water and Zhidan Group aquifer, Zhidan Group and Zhiluo Formation aquifer is 0.28, which belongs to the medium degree of hydraulic correlation. The hydraulic correlation degree between surface water and Zhiluo Formation aquifer is 0.43, indicating that hydraulic correlation is weak. At the same time, the surface pumping test of Zhidan Group aquifer and the underground dewatering test of Zhiluo Formation aquifer further indicate that there is a hydraulic connection between Zhidan Group aquifer and Zhiluo Formation aquifer. Zhidan Group aquifer and Zhiluo Formation aquifer are the main water-filling aquifers of mine.

Published
2024
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43. Early prediction of microvascular invasion (MVI) occurrence in hepatocellular carcinoma (HCC) by 18F-FDG PET/CT and laboratory data

Author

Tianyi Wang, Xue Chen, Huan Huang, and Ningyang Jia

Subjects
Hepatocellular carcinoma, Microvascular invasion, 18F-FDG PET/CT, Medicine
Abstract

Abstract Background Hepatocellular carcinoma (HCC) is one of the deadliest malignant tumors in China. Microvascular invasion (MVI) often indicates poor prognosis and metastasis in HCC patients. 18F-FDG PET–CT is a new imaging method commonly used to screen for tumor occurrence and evaluate tumor stage. Purpose This study attempted to predict the occurrence of MVI in early-stage HCC through 18F-FDG positron emission tomography (PET)/computed tomography (CT) imaging findings and laboratory data. Patients and methods A total of 113 patients who met the inclusion criteria were divided into two groups based on postoperative pathology: the MVI-positive group and MVI-negative group. We retrospectively analyzed the imaging findings and laboratory data of 113 patients. Imaging findings included tumor size, tumor maximum standard uptake value (SUVmaxT), and normal liver maximum standard uptake value (SUVmaxL). The ratios of SUVmaxT to SUVmaxL (SUVmaxT/L) and an SUVmaxT/L > 2 were defined as active tumor metabolism. The tumor size was indicated by the maximum diameter of the tumor, and a diameter greater than 5 cm was defined as a mass lesion. The laboratory data included the alpha-fetoprotein (AFP) level and the HBeAg level. An AFP concentration > 20 ng/mL was defined as a high AFP level. A HBeAg concentration > 0.03 NCU/mL was defined as HB-positive. Results The SUVmaxT/L (p = 0.003), AFP level (p = 0.008) and tumor size (p = 0.015) were significantly different between the two groups. Patients with active tumor metabolism, mass lesions and high AFP levels tended to be MVI positive. Binary logistic regression analysis verified that active tumor metabolism (OR = 4.124, 95% CI, 1.566–10.861; p = 0.004) and high AFP levels (OR = 2.702, 95% CI, 1.214–6.021; p = 0.015) were independent risk factors for MVI. The sensitivity of the combination of these two independent risk factors predicting HCC with MVI was 56.9% (29/51), the specificity was 83.9% (52/62) and the accuracy was 71.7% (81/113). Conclusion Active tumor metabolism and high AFP levels can predict the occurrence of MVI in HCC patients.

Published
2024
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44. An in situ exploration of how Fe/N/C oxygen reduction catalysts evolve during synthesis under pyrolytic conditions

Author

Shuhu Yin, Hongyuan Yi, Mengli Liu, Jian Yang, Shuangli Yang, Bin-Wei Zhang, Long Chen, Xiaoyang Cheng, Huan Huang, Rui Huang, Yanxia Jiang, Honggang Liao, and Shigang Sun

Subjects
Science
Abstract

Abstract In pursuing cheap and effective oxygen reduction catalysts, the Fe/N/C system emerges as a promising candidate. Nevertheless, the structural transformations of starting materials into Fe- and N-doped carbon catalysts remains poorly characterized under pyrolytic conditions. Here, we explore the evolution of Fe species and track the formation of Fe–N4 site development by employing diverse in-situ diagnostic techniques. In-situ heating microscopy reveals the initial formation of FeOx nanoparticles and subsequent internal migration within the carbon matrix, which stops once FeOx is fully reduced. The migration and decomposition of nanoparticles then leads to carbon layer reconstruction. Experimental and theoretical analysis reveals size-dependent behavior of FeOx where nanoparticles below 7 nm readily release Fe atoms to form Fe–N4 while nanoparticles with sizes >10 nm tend to coalesce and impede Fe–N4 site formation. The work visualizes the pyrolysis process of Fe/N/C materials, providing theoretical guidance for the rational design of catalysts.

Published
2024
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45. Neurostructural subgroup in 4291 individuals with schizophrenia identified using the subtype and stage inference algorithm

Author

Yuchao Jiang, Cheng Luo, Jijun Wang, Lena Palaniyappan, Xiao Chang, Shitong Xiang, Jie Zhang, Mingjun Duan, Huan Huang, Christian Gaser, Kiyotaka Nemoto, Kenichiro Miura, Ryota Hashimoto, Lars T. Westlye, Genevieve Richard, Sara Fernandez-Cabello, Nadine Parker, Ole A. Andreassen, Tilo Kircher, Igor Nenadić, Frederike Stein, Florian Thomas-Odenthal, Lea Teutenberg, Paula Usemann, Udo Dannlowski, Tim Hahn, Dominik Grotegerd, Susanne Meinert, Rebekka Lencer, Yingying Tang, Tianhong Zhang, Chunbo Li, Weihua Yue, Yuyanan Zhang, Xin Yu, Enpeng Zhou, Ching-Po Lin, Shih-Jen Tsai, Amanda L. Rodrigue, David Glahn, Godfrey Pearlson, John Blangero, Andriana Karuk, Edith Pomarol-Clotet, Raymond Salvador, Paola Fuentes-Claramonte, María Ángeles Garcia-León, Gianfranco Spalletta, Fabrizio Piras, Daniela Vecchio, Nerisa Banaj, Jingliang Cheng, Zhening Liu, Jie Yang, Ali Saffet Gonul, Ozgul Uslu, Birce Begum Burhanoglu, Aslihan Uyar Demir, Kelly Rootes-Murdy, Vince D. Calhoun, Kang Sim, Melissa Green, Yann Quidé, Young Chul Chung, Woo-Sung Kim, Scott R. Sponheim, Caroline Demro, Ian S. Ramsay, Felice Iasevoli, Andrea de Bartolomeis, Annarita Barone, Mariateresa Ciccarelli, Arturo Brunetti, Sirio Cocozza, Giuseppe Pontillo, Mario Tranfa, Min Tae M. Park, Matthias Kirschner, Foivos Georgiadis, Stefan Kaiser, Tamsyn E. Van Rheenen, Susan L. Rossell, Matthew Hughes, William Woods, Sean P. Carruthers, Philip Sumner, Elysha Ringin, Filip Spaniel, Antonin Skoch, David Tomecek, Philipp Homan, Stephanie Homan, Wolfgang Omlor, Giacomo Cecere, Dana D. Nguyen, Adrian Preda, Sophia I. Thomopoulos, Neda Jahanshad, Long-Biao Cui, Dezhong Yao, Paul M. Thompson, Jessica A. Turner, Theo G. M. van Erp, Wei Cheng, ENIGMA Schizophrenia Consortium, Jianfeng Feng, and ZIB Consortium

Subjects
Science
Abstract

Abstract Machine learning can be used to define subtypes of psychiatric conditions based on shared biological foundations of mental disorders. Here we analyzed cross-sectional brain images from 4,222 individuals with schizophrenia and 7038 healthy subjects pooled across 41 international cohorts from the ENIGMA, non-ENIGMA cohorts and public datasets. Using the Subtype and Stage Inference (SuStaIn) algorithm, we identify two distinct neurostructural subgroups by mapping the spatial and temporal ‘trajectory’ of gray matter change in schizophrenia. Subgroup 1 was characterized by an early cortical-predominant loss with enlarged striatum, whereas subgroup 2 displayed an early subcortical-predominant loss in the hippocampus, striatum and other subcortical regions. We confirmed the reproducibility of the two neurostructural subtypes across various sample sites, including Europe, North America and East Asia. This imaging-based taxonomy holds the potential to identify individuals with shared neurobiological attributes, thereby suggesting the viability of redefining existing disorder constructs based on biological factors.

Published
2024
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46. The involvement of krüppel-like transcription factor 2 in megakaryocytic differentiation induction by phorbol 12-myrestrat 13-acetate

Author

Zhen Wang, Zhongwen Liu, Pan Zhou, Xiaona Niu, Zhengdao Sun, Huan He, and Zunmin Zhu

Subjects
Krüppel-like transcription factor 2, Megakaryocytic differentiation, Phorbol 12-myrestrat 13-acetate, Regulatory mechanism, Therapeutics. Pharmacology, RM1-950
Abstract

Abstract Background Megakaryocytic differentiation is a complicated process regulated by a series of transcription factors in a context- and stage-dependent manner. Recent studies have suggested that krüppel-like transcription factor 2 (KLF2) is involved in the control of embryonic erythroid precursor cell differentiation and maturation. However, the function and mechanism of KLF2 in regulating megakaryocytic differentiation remain unclear. Methods The expression patterns of krüppel-like transcription factors (KLFs) during megakaryocytic differentiation were identified from public databases. Phorbol 12-myristate 13-acetate (PMA) treatment of the myeloid-erythroid-leukemic cell lines K562 and HEL were used as cellular megakaryocytic differentiation models. A lentiviral transduction system was utilized to achieve the goal of amplifying or reducing KLF2. The expression of KLF2 was examined using real-time PCR and western blot. The impact of KLF2 on the megakaryocytic differentiation of K562 cells was examined by flow cytometry, Giemsa staining, Phalloidin staining and western blot. RNA-sequencing (RNA-seq) and chromatin immunoprecipitation-sequencing (ChIP-seq) technologies were used to identify the KLF2-regulated targets. Results KLF2 is increased in the maturation process of megakaryocytes. KLF2 overexpression accelerated the PMA-induced megakaryocytic differentiation, as reflected by an increased percentage of CD41/CD61 cells, an increased number of polyploid cells, and an elevated expression of P21 and P27. KLF2 knockdown exhibited the opposite results, indicating that KLF2 knockdown suppressed the megakaryocytic differentiation. Further, combination of the RNA-seq and ChIP-seq results suggested that chimerin 1 (CHN1) and potassium voltage-gated channel subfamily Q member 5 (KCNQ5) may be target genes regulated of KLF2. Both CHN1 and KCNQ5 knockdown could block the megakaryocytic differentiation to some content. Conclusion This study implicated a regulatory role of KLF2 in megakaryocytic differentiation, which may suggest KLF2 as a target for illness with abnormal megakaryocytic differentiation.

Published
2024
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47. P.198 Durable AOC mediated exon 44 skipping in non-human primate muscle tissue and dystrophin protein restoration in DMD patient derived skeletal muscle cells

Author

Karamanlidis, G., primary, Etxaniz, U., additional, Missinato, M., additional, Diaz, M., additional, Bhardwaj, R., additional, Tyaglo, O., additional, Lemoine, K., additional, Marks, I., additional, Albin, T., additional, Leung, L., additional, Kovach, P., additional, Anderson, A., additional, Cochran, M., additional, Huan, H., additional, Younis, H., additional, Flanagan, M., additional, and Levin, A., additional

Published
2022
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