1,035 results on '"Davis, Jeffrey P."'
Search Results
2. Imaging topological polar structures in marginally twisted 2D semiconductors
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Vu, Thi-Hai-Yen, Bennett, Daniel, Pallewella, Gayani Nadeera, Uddin, Md Hemayet, Xing, Kaijian, Zhao, Weiyao, Lee, Seng Huat, Mao, Zhiqiang, Muir, Jack B., Jia, Linnan, Davis, Jeffrey A., Watanabe, Kenji, Taniguchi, Takashi, Adam, Shaffique, Sharma, Pankaj, Fuhrer, Michael S., and Edmonds, Mark T.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science - Abstract
Moire superlattices formed in van der Waals heterostructures due to twisting, lattice mismatch and strain present an opportunity for creating novel metamaterials with unique properties not present in the individual layers themselves. Ferroelectricity for example, arises due to broken inversion symmetry in twisted and strained bilayers of 2D semiconductors with stacking domains of alternating out-of-plane polarization. However, understanding the individual contributions of twist and strain to the formation of topological polar nanostructures remains to be established and has proven to be experimentally challenging. Inversion symmetry breaking has been predicted to give rise to an in-plane component of polarization along the domain walls, leading to the formation of a network of topologically non-trivial merons (half-skyrmions) that are Bloch-type for twisted and Neel-type for strained systems. Here we utilise angle-resolved, high-resolution vector piezoresponse force microscopy (PFM) to spatially resolve polarization components and topological polar nanostructures in marginally twisted bilayer WSe2, and provide experimental proof for the existence of topologically non-trivial meron/antimeron structures. We observe both Bloch-type and Neel-type merons, allowing us to differentiate between moire superlattices formed due to twist or heterogeneous strain. This first demonstration of non-trivial real-space topology in a twisted van der Waals heterostructure opens pathways for exploring the connection between twist and topology in engineered nano-devices.
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- 2024
3. Overlap chronic GVHD is associated with adverse survival outcomes compared to classic chronic GVHD.
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Gorfinkel, Lev, Raghunandan, Sharmila, Watkins, Benjamin, Hebert, Kyle, Neuberg, Donna, Bratrude, Brandi, Betz, Kayla, Yu, Alison, Choi, Sung, Davis, Jeffrey, Duncan, Christine, Giller, Roger, Grimley, Michael, Harris, Andrew, Jacobsohn, David, Lalefar, Nahal, Farhadfar, Nosha, Pulsipher, Michael, Shenoy, Shalini, Petrovic, Aleksandra, Schultz, Kirk, Yanik, Gregory, Blazar, Bruce, Horan, John, Langston, Amelia, Kean, Leslie, and Qayed, Muna
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Humans ,Graft vs Host Disease ,Male ,Female ,Chronic Disease ,Adult ,Middle Aged ,Disease-Free Survival ,Hematopoietic Stem Cell Transplantation ,Survival Rate ,Aged - Abstract
Chronic graft-versus-host-disease (cGVHD) is divided into two subtypes: classic (absence of acute GVHD features) and overlap cGVHD (ocGVHD), in which both chronic and acute GVHD clinical features are present simultaneously. While worse outcomes with ocGVHD have been reported, there are few recent analyses. We performed a secondary analysis of data from the ABA2 trial (N = 185), in which detailed GVHD data were collected prospectively and systematically adjudicated. Analyses included cumulative incidence of classic versus ocGVHD, their specific organ manifestations, global disease severity scores, non-relapse mortality (NRM), disease-free survival (DFS) and overall survival (OS) in these two cGVHD subtypes. Of 92 patients who developed cGVHD, 35 were classified as ocGVHD. The 1-year cumulative incidence, organ involvement, and global severity of classic and ocGVHD were similar between ABA2 patients receiving CNI/MTX+placebo and CNI/MTX+abatacept; thus, cohorts were combined for ocGVHD evaluation. This analysis identified ocGVHD as having significantly higher severity at presentation and at maximum global severity compared to classic cGVHD. OS and DFS were significantly lower for ocGVHD versus classic cGVHD. OcGVHD is associated with increased cGVHD severity scores, and is associated with decreased OS and DFS compared to classic cGVHD, underscoring the high risks with this cGVHD subtype.
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- 2024
4. Intrinsic defect engineering of CVD grown monolayer MoS$_2$ for tuneable functional nanodevices
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Abidi, Irfan H., Giridhar, Sindhu Priya, Tollerud, Jonathan O., Limb, Jake, Mazumder, Aishani, Mayes, Edwin LH, Murdoch, Billy J., Xu, Chenglong, Bhoriya, Ankit, Ranjan, Abhishek, Ahmed, Taimur, Li, Yongxiang, Davis, Jeffrey A., Bentley, Cameron L., Russo, Salvy P., Della Gaspera, Enrico, and Walia, Sumeet
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Physics - Applied Physics ,Condensed Matter - Materials Science - Abstract
Defects in atomically thin materials can drive new functionalities and expand applications to multifunctional systems that are monolithically integrated. An ability to control formation of defects during the synthesis process is an important capability to create practical deployment opportunities. Molybdenum disulfide (MoS$_2$), a two-dimensional (2D) semiconducting material harbors intrinsic defects that can be harnessed to achieve tuneable electronic, optoelectronic, and electrochemical devices. However, achieving precise control over defect formation within monolayer MoS$_2$, while maintaining the structural integrity of the crystals remains a notable challenge. Here, we present a one-step, in-situ defect engineering approach for monolayer MoS$_2$ using a pressure dependent chemical vapour deposition (CVD) process. Monolayer MoS$_2$ grown in low-pressure CVD conditions (LP-MoS$_2$) produces sulfur vacancy (Vs) induced defect rich crystals primarily attributed to the kinetics of the growth conditions. Conversely, atmospheric pressure CVD grown MoS$_2$ (AP-MoS$_2$) passivates these Vs defects with oxygen. This disparity in defect profiles profoundly impacts crucial functional properties and device performance. AP-MoS$_2$ shows a drastically enhanced photoluminescence, which is significantly quenched in LP-MoS$_2$ attributed to in-gap electron donor states induced by the Vs defects. However, the n-doping induced by the Vs defects in LP-MoS$_2$ generates enhanced photoresponsivity and detectivity in our fabricated photodetectors compared to the AP-MoS$_2$ based devices. Defect-rich LP-MoS$_2$ outperforms AP-MoS$_2$ as channel layers of field-effect transistors (FETs), as well as electrocatalytic material for hydrogen evolution reaction (HER). This work presents a single-step CVD approach for in-situ defect engineering in monolayer MoS$_2$ and presents a pathway to control defects in other monolayer material systems., Comment: 29 pages, 5 figures
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- 2023
5. Floquet engineering in the presence of optically excited carriers
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Conway, Mitchell A., Tollerud, Jonathan O., Vu, Thi-Hai-Yen, Watanabe, Kenji, Taniguchi, Takashi, Fuhrer, Michael S., Edmonds, Mark T., and Davis, Jeffrey A.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Other Condensed Matter ,Physics - Optics - Abstract
Floquet engineering provides an optical means to manipulate electronic bandstructures, however, carriers excited by the pump field can lead to an effective heating, and can obscure measurement of the band changes. A recent demonstration of the effects of Floquet engineering on a coherent ensemble of excitons in monolayer WS$_2$ proved particularly sensitive to non-adiabatic effects, while still being able to accurately resolve bandstructure changes. Here, we drive an AC-Stark effect in monolayer WS$_2$ using pulses with constant fluence but varying pulse duration (from 25-235~fs). With shorter pump pulses, the corresponding increase in peak intensity introduces additional carriers via two-photon absorption, leading to additional decoherence and peak broadening (which makes it difficult to resolve the AC-Stark shift). We use multidimensional coherent spectroscopy to create a coherent ensemble of excitons in monolayer WS$_2$ and measure the evolution of the coherence throughout the duration of the Floquet pump pulse. Changes to the amplitude of the macroscopic coherence quantifies the additional broadening. At the same time, the evolution of the average phase allows the instantaneous changes to the bandstructure to be quantified, and is not impacted by the additional broadening. This approach to measuring the evolution of Floquet-Bloch states demonstrates a means to quantify effective heating and non-adiabaticity caused by excited carriers, while at the same time resolving the coherent evolution of the bandstructure.
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- 2023
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6. Effects of Floquet Engineering on the Coherent Exciton Dynamics in Monolayer WS$_2$
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Conway, Mitchell A., Earl, Stuart K., Muir, Jack B., Vu, Thi-Hai-Yen, Tollerud, Jonathan O., Watanabe, Kenji, Taniguchi, Takashi, Fuhrer, Michael S., Edmonds, Mark T., and Davis, Jeffrey A.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Optics - Abstract
Coherent optical manipulation of electronic bandstructures via Floquet Engineering is a promising means to control quantum systems on an ultrafast timescale. However, the ultrafast switching on/off of the driving field comes with questions regarding the limits of validity of the Floquet formalism, which is defined for an infinite periodic drive, and to what extent the transient changes can be driven adibatically. Experimentally addressing these questions has been difficult, in large part due to the absence of an established technique to measure coherent dynamics through the duration of the pulse. Here, using multidimensional coherent spectroscopy we explicitly excite, control, and probe a coherent superposition of excitons in the $K$ and $K^\prime$ valleys in monolayer WS$_2$. With a circularly polarized, red-detuned, pump pulse, the degeneracy of the $K$ and $K^\prime$ excitons can be lifted and the phase of the coherence rotated. We demonstrate phase rotations during the 100 fs driving pulse that exceed $\pi$, and show that this can be described by a combination of the AC-Stark shift of excitons in one valley and Bloch-Siegert shift of excitons in the opposite valley. Despite showing a smooth evolution of the phase that directly follows the intensity envelope of the pump pulse, the process is not perfectly adiabatic. By measuring the magnitude of the macroscopic coherence as it evolves before, during, and after the pump pulse we show that there is additional decoherence caused by power broadening in the presence of the pump. This non-adiabaticity may be a problem for many applications, such as manipulating q-bits in quantum information processing, however these measurements also suggest ways such effects can be minimised or eliminated.
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- 2023
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7. IRAK4 degrader in hidradenitis suppurativa and atopic dermatitis: a phase 1 trial
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Ackerman, Lindsay, Acloque, Gerard, Bacchelli, Sandro, Schwartz, Howard, Feinstein, Brian J., La Stella, Phillip, Alavi, Afsaneh, Gollerkeri, Ashwin, Davis, Jeffrey, Campbell, Veronica, McDonald, Alice, Agarwal, Sagar, Karnik, Rahul, Shi, Kelvin, Mishkin, Aimee, Culbertson, Jennifer, Klaus, Christine, Enerson, Bradley, Massa, Virginia, Kuhn, Eric, Sharma, Kirti, Keaney, Erin, Barnes, Randy, Chen, Dapeng, Zheng, Xiaozhang, Rong, Haojing, Sabesan, Vijay, Ho, Chris, Mainolfi, Nello, Slavin, Anthony, and Gollob, Jared A.
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- 2023
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8. Exciton-polaron interactions in monolayer WS$_2$
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Muir, Jack B., Levinsen, Jesper, Earl, Stuart K., Conway, Mitchell A., Cole, Jared H., Wurdack, Matthias, Mishra, Rishabh, Ing, David J., Estrecho, Eliezer, Lu, Yuerui, Efimkin, Dmitry K., Tollerud, Jonathan O., Ostrovskaya, Elena A., Parish, Meera M., and Davis, Jeffrey A.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Other Condensed Matter ,Physics - Optics - Abstract
Interactions between quasiparticles are of fundamental importance and ultimately determine the macroscopic properties of quantum matter. A famous example is the phenomenon of superconductivity, which arises from attractive electron-electron interactions that are mediated by phonons or even other more exotic fluctuations in the material. Here we introduce mobile exciton impurities into a two-dimensional electron gas and investigate the interactions between the resulting Fermi polaron quasiparticles. We employ multi-dimensional coherent spectroscopy on monolayer WS$_2$, which provides an ideal platform for determining the nature of polaron-polaron interactions due to the underlying trion fine structure and the valley specific optical selection rules. At low electron doping densities, we find that the dominant interactions are between polaron states that are dressed by the same Fermi sea. In the absence of bound polaron pairs (bipolarons), we show using a minimal microscopic model that these interactions originate from a phase-space filling effect, where excitons compete for the same electrons. We furthermore reveal the existence of a bipolaron bound state with remarkably large binding energy, involving excitons in different valleys cooperatively bound to the same electron. Our work lays the foundation for probing and understanding strong electron correlation effects in two-dimensional layered structures such as moir\'e superlattices.
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- 2022
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9. Direct Measurement of Biexcitons in Monolayer WS2
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Conway, Mitchell, Muir, Jack, Earl, Stuart, Wurdack, Matthias, Mishra, Rishabh, Tollerud, Jonathan, and Davis, Jeffrey
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science ,Physics - Optics - Abstract
The optical properties of atomically thin transition metal dichalcogenides (TMDCs) are dominated by Coulomb bound quasi-particles, such as excitons, trions, and biexcitons. Due to the number and density of possible states, attributing different spectral peaks to the specific origin can be difficult. In particular, there has been much conjecture around the presence, binding energy and/or nature of biexcitons in these materials. In this work, we remove any ambiguity in identifying and separating the optically excited biexciton in monolayer WS2 using two-quantum multidimensional coherent spectroscopy (2Q-MDCS), a technique that directly and selectively probes doubly-excited states, such as biexcitons. The energy difference between the unbound two-exciton state and the biexciton is the fundamental definition of biexciton binding energy and is measured to be 26 \pm 2 meV. Furthermore, resolving the biexciton peaks in 2Q-MDCS allows us to identify that the biexciton observed here is composed of two bright excitons in opposite valleys.
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- 2021
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10. Short-Term Learners' Motivation Modeling in Web Based Education System
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Shabbir, Shahzad, Ayub, Muhammad Adnan, Khan, Farman Ali, and Davis, Jeffrey
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Recent research regarding personalized web based educational systems demonstrate learners' motivation to be an essential component of the learning model. This is due to the fact that low motivation results in either students' less engagement or complete drop out from the learning activities. A learner motivation model is considered to be a set of perceptions and beliefs that the system has developed about a learner. This includes both short-term and long-term motivation of learners. Short-term motivation encompasses specific, challenging and attainable goals that develop in the limited timespan. On the other hand, long-term motivation indicates a sort of continuing commitment that is required to complete assigned task. Since, short-term motivational problems span for a limited period of time such as a session, therefore, needs to be addressed in real-time to keep the learner engaged in the learning process. This paper proposes the framework of a domain independent short-term learner motivation model based on Keller ARCS motivation theory and Social Cognitive Theory. The proposed motivation identification framework consists of two modules. The primary module deals with real time identification of motivation, and the secondary module maintains the profile of learners associated with the short-term motivation. [For the full proceedings, see ED621620.]
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- 2020
11. Constraining anomalous Higgs boson couplings to virtual photons
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Davis, Jeffrey, Gritsan, Andrei V., Guerra, Lucas S. Mandacaru, Kyriacou, Savvas, Roskes, Jeffrey, and Schulze, Markus
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High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
We present a study of Higgs boson production in vector boson fusion and in association with a vector boson and its decay to two vector bosons, with a focus on the treatment of virtual loops and virtual photons. Our analysis is performed with the JHU generator framework. Comparisons are made to several other frameworks, and the results are expressed in terms of an effective field theory. New features of this study include a proposal on how to handle singularities involving Higgs boson decays to light fermions via photons, calculation of the partial Higgs boson width in the presence of anomalous couplings to photons, a comparison of the next-to-leading-order electroweak corrections to effects from effective couplings, and phenomenological observations regarding the special role of intermediate photons in analysis of LHC data in the effective field theory framework. Some of these features are illustrated with projections for experimental measurements with the full LHC and HL-LHC datasets., Comment: 32 pages, 14 figures
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- 2021
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12. Lower-Luminosity Obscured AGN Host Galaxies are Not Predominantly in Major-Merging Systems at Cosmic Noon
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Lambrides, Erini, Chiaberge, Marco, Heckman, Timothy, Kirkpatrick, Allison, Meyer, Eileen T., Petric, Andreea, Hall, Kirsten, Long, Arianna, Watts, Duncan J., Gilli, Roberto, Simons, Raymond, Tchernyshyov, Kirill, Rodriguez-Gomez, Vicente, Vito, Fabio, De La Vega, Alexander, Davis, Jeffrey R., Kocevski, Dale D, and Norman, Colin
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Astrophysics - Astrophysics of Galaxies - Abstract
For over 60 years, the scientific community has studied actively growing central super-massive black holes (active galactic nuclei -- AGN) but fundamental questions on their genesis remain unanswered. Numerical simulations and theoretical arguments show that black hole growth occurs during short-lived periods ($\sim$ 10$^{7}$ -10$^{8}$ yr) of powerful accretion. Major mergers are commonly invoked as the most likely dissipative process to trigger the rapid fueling of AGN. If the AGN-merger paradigm is true, we expect galaxy mergers to coincide with black hole accretion during a heavily obscured AGN phase (N$_H$ $ > 10^{23}$ cm$^{-2}$). Starting from one of the largest samples of obscured AGN at 0.5 $<$ $z$ $<$ 3.1, we select 40 non-starbursting lower-luminosity obscured AGN. We then construct a one-to-one matched redshift- and near-IR magnitude-matched non-starbursting inactive galaxy control sample. Combining deep color \textit{Hubble Space Telescope} imaging and a novel method of human classification, we test the merger-AGN paradigm prediction that heavily obscured AGN are strongly associated with galaxies undergoing a major merger. On the total sample of 80 galaxies, we estimate each individual classifier's accuracy at identifying merging galaxies/post-merging systems and isolated galaxies. We calculate the probability of each galaxy being in either a major merger or isolated system, given the accuracy of the human classifiers and the individual classifications of each galaxy. We do not find statistically significant evidence that obscured AGN at cosmic noon are predominately found in systems with evidence of significant merging/post-merging features., Comment: 19 pages, 11 figures, accepted in ApJ
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- 2021
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13. Ship-to-objective maneuver: Will this dog hunt?
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Davis, Jeffrey P., Maj
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AMPHIBIOUS OPERATIONS ,LITTORAL OPERATIONS ,ATTACK AND DEFENSE (MILITARY SCIENCE) - Abstract
illus bibliog
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- 1998
14. Lunar Volatiles and Solar System Science
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Prem, Parvathy, Kereszturi, Ákos, Deutsch, Ariel N., Hibbitts, Charles A., Schmidt, Carl A., Grava, Cesare, Honniball, Casey I., Hardgrove, Craig J., Pieters, Carlé M., Goldstein, David B., Barker, Donald C., Needham, Debra H., Hurley, Dana M., Mazarico, Erwan, Dominguez, Gerardo, Patterson, G. Wesley, Kramer, Georgiana Y., Brisset, Julie, Gillis-Davis, Jeffrey J., Mitchell, Julie L., Szalay, Jamey R., Halekas, Jasper S., Keane, James T., Head, James W., Mandt, Kathleen E., Robinson, Katharine L., Luchsinger, Kristen M., Magaña, Lizeth O., Siegler, Matthew A., Landis, Margaret E., Poston, Michael J., Petro, Noah E., Lucey, Paul G., Killen, Rosemary M., Li, Shuai, Narendranath, Shyama, Shukla, Shashwat, Barrett, Thomas J., Stubbs, Timothy J., Orlando, Thomas M., and Farrell, William M.
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Astrophysics - Instrumentation and Methods for Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Understanding the origin and evolution of the lunar volatile system is not only compelling lunar science, but also fundamental Solar System science. This white paper (submitted to the US National Academies' Decadal Survey in Planetary Science and Astrobiology 2023-2032) summarizes recent advances in our understanding of lunar volatiles, identifies outstanding questions for the next decade, and discusses key steps required to address these questions.
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- 2020
15. Can the Corps counter the threat?
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Davis, Jeffrey P., Capt
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MISSILE DEFENSE ,MISSILES - Interception ,MISSILE TYPE - Patriot ,MARINE CORPS - United States ,AIR DEFENSES - United States - Abstract
illus bibliog
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- 1997
16. Multidimensional Analysis of Excitonic Spectra of Monolayers of Tungsten Disulphide: Towards Computer Aided Identification of Structural and Environmental Perturbations of 2D Materials
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Kolesnichenko, Pavel V., Zhang, Qianhui, Zheng, Changxi, Fuhrer, Michael S., and Davis, Jeffrey A.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science ,Physics - Computational Physics - Abstract
Despite 2D materials holding great promise for a broad range of applications, the proliferation of devices and their fulfillment of real-life demands are still far from being realized. Experimentally obtainable samples commonly experience a wide range of perturbations (ripples and wrinkles, point and line defects, grain boundaries, strain field, doping, water intercalation, oxidation, edge reconstructions) significantly deviating the properties from idealistic models. These perturbations, in general, can be entangled or occur in groups with each group forming a complex perturbation making the interpretations of observable physical properties and the disentanglement of simultaneously acting effects a highly non-trivial task even for an experienced researcher. Here we generalise statistical correlation analysis of excitonic spectra of monolayer WS2, acquired by hyperspectral absorption and photoluminescence imaging, to a multidimensional case, and examine multidimensional correlations via unsupervised machine learning algorithms. Using principle component analysis we are able to identify 4 dominant components that are correlated with tensile strain, disorder induced by adsorption or intercalation of environmental molecules, multi-layer regions and charge doping, respectively. This approach has the potential to determine the local environment of WS2 monolayers or other 2D materials from simple optical measurements, and paves the way towards advanced, machine-aided, characterisation of monolayer matter., Comment: 12 pages, 4 figures, supplementary materials
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- 2020
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17. Phase II Trial of Costimulation Blockade With Abatacept for Prevention of Acute GVHD.
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Norkin, Maxim, Farhadfar, Nosha, Pulsipher, Michael, Shenoy, Shalini, Petrovic, Aleksandra, Schultz, Kirk, Yanik, Gregory, Waller, Edmund, Levine, John, Ferrara, James, Blazar, Bruce, Langston, Amelia, Horan, John, Kean, Leslie, Watkins, Benjamin, Qayed, Muna, McCracken, Courtney, Bratrude, Brandi, Betz, Kayla, Suessmuth, Yvonne, Yu, Alison, Sinclair, Shauna, Furlan, Scott, Bosinger, Steven, Tkachev, Victor, Rhodes, James, Tumlin, Audrey, Narayan, Alexandria, Cribbin, Kayla, Gillespie, Scott, Gooley, Ted, Pasquini, Marcelo, Hebert, Kyle, Kapoor, Urvi, Rogatko, Andre, Tighiouart, Mourad, Kim, Sungjin, Bresee, Catherine, Choi, Sung, Davis, Jeffrey, Duncan, Christine, Giller, Roger, Grimley, Michael, Harris, Andrew, Jacobsohn, David, and Lalefar, Nahal
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Abatacept ,Adolescent ,Adult ,Aged ,Child ,Cyclosporine ,Graft vs Host Disease ,Hematopoietic Stem Cell Transplantation ,Humans ,Immunosuppressive Agents ,Male ,Methotrexate ,Middle Aged ,Tacrolimus ,Young Adult - Abstract
PURPOSE: Severe (grade 3-4) acute graft-versus-host disease (AGVHD) is a major cause of death after unrelated-donor (URD) hematopoietic cell transplant (HCT), resulting in particularly high mortality after HLA-mismatched transplantation. There are no approved agents for AGVHD prevention, underscoring the critical unmet need for novel therapeutics. ABA2 was a phase II trial to rigorously assess safety, efficacy, and immunologic effects of adding T-cell costimulation blockade with abatacept to calcineurin inhibitor (CNI)/methotrexate (MTX)-based GVHD prophylaxis, to test whether abatacept could decrease AGVHD. METHODS: ABA2 enrolled adults and children with hematologic malignancies under two strata: a randomized, double-blind, placebo-controlled stratum (8/8-HLA-matched URD), comparing CNI/MTX plus abatacept with CNI/MTX plus placebo, and a single-arm stratum (7/8-HLA-mismatched URD) comparing CNI/MTX plus abatacept versus CNI/MTX CIBMTR controls. The primary end point was day +100 grade 3-4 AGVHD, with day +180 severe-AGVHD-free-survival (SGFS) a key secondary end point. Sample sizes were calculated using a higher type-1 error (0.2) as recommended for phase II trials, and were based on predicting that abatacept would reduce grade 3-4 AGVHD from 20% to 10% (8/8s) and 30% to 10% (7/8s). ABA2 enrolled 142 recipients (8/8s, median follow-up = 716 days) and 43 recipients (7/8s, median follow-up = 708 days). RESULTS: In 8/8s, grade 3-4 AGVHD was 6.8% (abatacept) versus 14.8% (placebo) (P = .13, hazard ratio = 0.45). SGFS was 93.2% (CNI/MTX plus abatacept) versus 82% (CNI/MTX plus placebo, P = .05). In the smaller 7/8 cohort, grade 3-4 AGVHD was 2.3% (CNI/MTX plus abatacept, intention-to-treat population), which compared favorably with a nonrandomized matched cohort of CNI/MTX (30.2%, P < .001), and the SGFS was better (97.7% v 58.7%, P < .001). Immunologic analysis revealed control of T-cell activation in abatacept-treated patients. CONCLUSION: Adding abatacept to URD HCT was safe, reduced AGVHD, and improved SGFS. These results suggest that abatacept may substantially improve AGVHD-related transplant outcomes, with a particularly beneficial impact on HLA-mismatched HCT.
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- 2021
18. Disentangling the effects of doping, strain and defects in monolayer WS2 by optical spectroscopy
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Kolesnichenko, Pavel V., Zhang, Qianhui, Zheng, Changxi, Fuhrer, Michael S., and Davis, Jeffrey A.
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Condensed Matter - Materials Science ,Physics - Chemical Physics ,Physics - Optics - Abstract
Monolayers of transition metal dichalcogenides (TMdC) are promising candidates for realization of a new generation of optoelectronic devices. The optical properties of these two-dimensional materials, however, vary from flake to flake, or even across individual flakes, and change over time, all of which makes control of the optoelectronic properties challenging. There are many different perturbations that can alter the optical properties, including charge doping, defects, strain, oxidation, and water intercalation. Identifying which perturbations are present is usually not straightforward and requires multiple measurements using multiple experimental modalities, which presents barriers when attempting to optimise preparation of these materials. Here, we apply highresolution photoluminescence and differential reflectance hyperspectral imaging in situ to CVD-grown WS2 monolayers. By combining these two optical measurements and using a statistical correlation analysis we are able to disentangle three contributions modulating optoelectronic properties of these materials: electron doping, strain and defects. In separating these contributions, we also observe that the B-exciton energy is less sensitive to variations in doping density than A-excitons., Comment: 27 pages, 5 figures
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- 2019
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19. Background-free time-resolved coherent Raman spectroscopy (CSRS and CARS): heterodyne detection of low-energy vibrations and recognition of excited-state contributions
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Kolesnichenko, Pavel, Tollerud, Jonathan O., and Davis, Jeffrey A.
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Physics - Optics ,Physics - Atomic Physics - Abstract
Coherent Raman scattering (CRS) spectroscopy techniques have been widely developed and optimized for different applications in biomedicine and fundamental science. The most utilized CRS technique has been coherent anti-Stokes Raman scattering (CARS), and more recently, stimulated Raman scattering (SRS). Coherent Stokes Raman scattering (CSRS) has been largely ignored mainly because it is often strongly affected by fluorescence, particularly for resonance enhanced measurements. However, in the cases of resonant excitation the information contained in the CSRS signal can be different and complementary to that of CARS. Here we combine the approaches of pulse shaping, interferometric heterodyne detection, 8-step phase cycling and Fourier-transform of time-domain measurements, developed in CARS and 2D electronic spectroscopy communities, to measure resonant CSRS and CARS spectra using a Titanium:sapphire oscillator. The signal is essentially background-free (both fluorescent and non-resonant background signals are suppressed) with high spectral resolution and high sensitivity, and can access low-energy modes down to ~30 cm-1. We demonstrate the ability to easily select between CSRS and CARS schemes and show an example in which acquisition of both CSRS and CARS spectra allows vibrational modes on the excited electronic state to be distinguished from those on the ground electronic state., Comment: Main text: 14 pages, 4 figures. Supplementary: 14 pages, 12 figures
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- 2018
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20. Zein and lignin-based nanoparticles as soybean seed treatment: translocation and impact on seed and plant health
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Kacsó, Tímea, Hanna, Eban A., Salinas, Fallon, Astete, Carlos E., Bodoki, Ede, Oprean, Radu, Price, Paul P., Doyle, Vinson P., Bonser, Colin A. R., Davis, Jeffrey A., and Sabliov, Cristina M.
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- 2022
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21. UAV (unmanned aerial vehicle) company: Should it be a VMO (fixed-wing Marine observation) squadron?
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Davis, Jeffrey P., Capt and Lott, Damien X., Capt
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REMOTELY PILOTED VEHICLES ,MARINE CORPS - United States - Equipment ,MARINE CORPS AVIATION - Equipment - Abstract
illus
- Published
- 1994
22. Persistent coherence of quantum superpositions in an optimally doped cuprate revealed by 2D spectroscopy
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Novelli, Fabio, Tollerud, Jonathan O., Prabhakaran, Dharmalingam, and Davis, Jeffrey A.
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Condensed Matter - Superconductivity ,Physics - Optics - Abstract
Understanding of the precise mechanisms of high-temperature superconductivity is elusive. In particular, in order to solve the puzzle of the pairing mechanism, it is important to understand the detailed nature of the excitations at energies around the superconducting gap. While measurements of the dynamics of excited electronic populations have been able to give some insight, they have largely neglected the intricate dynamics of quantum coherence. Here, we apply multidimensional coherent spectroscopy for the first time to a prototypical cuprate and report unprecedented coherent dynamics persisting for ~500 fs, originating directly from the quantum superposition of optically excited states separated by 20 - 60 meV. These results reveal the correlation between high and low energy excitations, and indicate that the interplay between many-body states on different energy scales conserves phase coherence. In revealing these dynamics we demonstrate that multidimensional coherent spectroscopy can address electronic correlations and interrogate many-body quantum systems in unprecedented ways.
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- 2017
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23. Short-Term and Long-Term Learners' Motivation Modeling in Web-Based Educational Systems
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Shabbir, Shahzad, Ayub, Muhammad Adnan, Khan, Farman Ali, and Davis, Jeffrey
- Abstract
Purpose: Short-term motivation encompasses specific, challenging and attainable goals that develop in the limited timespan. On the other hand, long-term motivation indicates a sort of continuing commitment that is required to complete assigned task. As short-term motivational problems span for a limited period of time, such as a session, therefore, they need to be addressed in real time to keep the learner engaged in the learning process. Similarly, long-term learners' motivation plays an equally important role to retain the learner in the long run and minimize the risk of dropout. Therefore, the purpose of this study is to incorporate a comprehensive learner motivation model that is based on short-term and long-term aspects of the learners' motivation. This approach enables Web-based educational systems to identify the real-time motivational state of the learner and provide personalized interventions to keep the learners engaged in learning process. Design/methodology/approach: Recent research regarding personalized Web-based educational systems demonstrates learner's motivation to be an essential component of the learning model. This is because of the fact that low motivation results in either students' less engagement or complete drop out from the learning activities. A learner motivation model is considered to be a set of perceptions and beliefs that the system has developed about a learner. This includes both short-term and long-term motivations of leaners. Findings: This study proposed a framework of a domain independent learners' motivation model based on firm educational theories. The proposed framework consists of two modules. The primary module deals with real-time identification of motivation and logging off activities such as login, forum participation and adherence to assessment deadline. Secondary module maintains the profile of leaners associated with both short-term and long-term motivation. A study was conducted to verify the impact of learners' motivation model and personalized interventional strategies based on proposed model, using Systematical Information Education Method assessment standards. The results show an increase in motivational index and the characteristics associated with motivation during the conducted study. Originality/value: Motivational diagnosis is important for both traditional classrooms and Web-based education systems. It is one of the major elements that contribute in the success of the learning process. However, dropout rate among online students is very high, which leads to incorporate motivational elements in more personalized way because motivated students will retain the course until they successfully complete it. Hence, identifying learner's motivation, updating learners' motivation model based on this identification and providing personalized interventions are the key for the success of Web-based educational systems.
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- 2021
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24. Outcomes of Measurable Residual Disease in Pediatric Acute Myeloid Leukemia before and after Hematopoietic Stem Cell Transplant: Validation of Difference from Normal Flow Cytometry with Chimerism Studies and Wilms Tumor 1 Gene Expression
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Jacobsohn, David A, Loken, Michael R, Fei, Mingwei, Adams, Alexia, Brodersen, Lisa Eidenschink, Logan, Brent R, Ahn, Kwang Woo, Shaw, Bronwen E, Kletzel, Morris, Olszewski, Marie, Khan, Sana, Meshinchi, Soheil, Keating, Amy, Harris, Andrew, Teira, Pierre, Duerst, Reggie E, Margossian, Steven P, Martin, Paul L, Petrovic, Aleksandra, Dvorak, Christopher C, Nemecek, Eneida R, Boyer, Michael W, Chen, Allen R, Davis, Jeffrey H, Shenoy, Shalini, Savasan, Sureyya, Hudspeth, Michelle P, Adams, Roberta H, Lewis, Victor A, Kheradpour, Albert, Kasow, Kimberly A, Gillio, Alfred P, Haight, Ann E, Bhatia, Monica, Bambach, Barbara J, Haines, Hilary L, Quigg, Troy C, Greiner, Robert J, Talano, Julie-An M, Delgado, David C, Cheerva, Alexandra, Gowda, Madhu, Ahuja, Sanjay, Ozkaynak, Mehmet, Mitchell, David, Schultz, Kirk R, Fry, Terry J, Loeb, David M, and Pulsipher, Michael A
- Subjects
Biomedical and Clinical Sciences ,Cardiovascular Medicine and Haematology ,Pediatric ,Rare Diseases ,Stem Cell Research - Nonembryonic - Human ,Clinical Research ,Transplantation ,Pediatric Research Initiative ,Hematology ,Regenerative Medicine ,Genetics ,Stem Cell Research ,Cancer ,Pediatric Cancer ,Detection ,screening and diagnosis ,4.2 Evaluation of markers and technologies ,Inflammatory and immune system ,Adolescent ,Adult ,Allografts ,Child ,Child ,Preschool ,Disease-Free Survival ,Female ,Flow Cytometry ,Hematopoietic Stem Cell Transplantation ,Humans ,Infant ,Infant ,Newborn ,Leukemia ,Myeloid ,Acute ,Male ,Neoplasm ,Residual ,Transplantation Conditioning ,Transplantation ,Homologous ,Unrelated Donors ,WT1 Proteins ,Cytogenetics and molecular genetics ,Measurable residual disease ,Stem cell transplantation ,Laboratory hematology ,Clinical Sciences ,Immunology ,Cardiovascular medicine and haematology - Abstract
We enrolled 150 patients in a prospective multicenter study of children with acute myeloid leukemia undergoing hematopoietic stem cell transplantation (HSCT) to compare the detection of measurable residual disease (MRD) by a "difference from normal" flow cytometry (ΔN) approach with assessment of Wilms tumor 1 (WT1) gene expression without access to the diagnostic specimen. Prospective analysis of the specimens using this approach showed that 23% of patients screened for HSCT had detectable residual disease by ΔN (.04% to 53%). Of those patients who proceeded to transplant as being in morphologic remission, 10 had detectable disease (.04% to 14%) by ΔN. The disease-free survival of this group was 10% (0 to 35%) compared with 55% (46% to 64%, P < .001) for those without disease. The ΔN assay was validated using the post-HSCT specimen by sorting abnormal or suspicious cells to confirm recipient or donor origin by chimerism studies. All 15 patients who had confirmation of tumor detection relapsed, whereas the 2 patients with suspicious phenotype cells lacking this confirmation did not. The phenotype of the relapse specimen was then used retrospectively to assess the pre-HSCT specimen, allowing identification of additional samples with low levels of MRD involvement that were previously undetected. Quantitative assessment of WT1 gene expression was not predictive of relapse or other outcomes in either pre- or post-transplant specimens. MRD detected by ΔN was highly specific, but did not identify most relapsing patients. The application of the assay was limited by poor quality among one-third of the specimens and lack of a diagnostic phenotype for comparison.
- Published
- 2018
25. Interactions between Fermi polarons in monolayer WS2
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Muir, Jack B., Levinsen, Jesper, Earl, Stuart K., Conway, Mitchell A., Cole, Jared H., Wurdack, Matthias, Mishra, Rishabh, Ing, David J., Estrecho, Eliezer, Lu, Yuerui, Efimkin, Dmitry K., Tollerud, Jonathan O., Ostrovskaya, Elena A., Parish, Meera M., and Davis, Jeffrey A.
- Published
- 2022
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26. Time-domain THz spectroscopy reveals coupled protein-hydration dielectric response in solutions of native and fibrils of human lyso-zyme
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Novelli, Fabio, Pour, Saeideh Ostovar, Tollerud, Jonathan, Roozbeh, Ashkan, Appadoo, Dominique R. T., Blanch, Ewan W., and Davis, Jeffrey A.
- Subjects
Physics - Biological Physics - Abstract
Here we reveal details of the interaction between human lysozyme proteins, both native and fibrils, and their water environment by intense terahertz time domain spectroscopy. With the aid of a rigorous dielectric model, we determine the amplitude and phase of the oscillating dipole induced by the THz field in the volume containing the protein and its hydration water. At low concentrations, the amplitude of this induced dipolar response decreases with increasing concentration. Beyond a certain threshold, marking the onset of the interactions between the extended hydration shells, the amplitude remains fixed but the phase of the induced dipolar response, which is initially in phase with the applied THz field, begins to change. The changes observed in the THz response reveal protein-protein interactions me-diated by extended hydration layers, which may control fibril formation and may have an important role in chemical recognition phenomena.
- Published
- 2017
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27. Adversarial Listening in Argumentation
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Davis, Jeffrey and Godden, David
- Published
- 2021
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28. Germline SAMD9 and SAMD9L mutations are associated with extensive genetic evolution and diverse hematologic outcomes
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Wong, Jasmine C, Bryant, Victoria, Lamprecht, Tamara, Ma, Jing, Walsh, Michael, Schwartz, Jason, del pilar Alzamora, Maria, Mullighan, Charles G, Loh, Mignon L, Ribeiro, Raul, Downing, James R, Carroll, William L, Davis, Jeffrey, Gold, Stuart, Rogers, Paul C, Israels, Sara, Yanofsky, Rochelle, Shannon, Kevin, and Klco, Jeffery M
- Subjects
Pediatric Cancer ,Hematology ,Genetics ,Cancer ,Childhood Leukemia ,Rare Diseases ,Clinical Research ,Pediatric ,2.1 Biological and endogenous factors ,Aetiology ,Cell Cycle ,Chromosome Deletion ,Chromosome Disorders ,Chromosomes ,Human ,Pair 7 ,Disease Progression ,Evolution ,Molecular ,Female ,Gene Expression Regulation ,Neoplastic ,Genetic Predisposition to Disease ,Germ-Line Mutation ,Hematologic Neoplasms ,Humans ,Intracellular Signaling Peptides and Proteins ,Leukemia ,Myeloid ,Acute ,Male ,Myelodysplastic Syndromes ,Neoplasms ,Pedigree ,Proteins ,Tumor Suppressor Proteins ,Leukemias - Abstract
Germline SAMD9 and SAMD9L mutations cause a spectrum of multisystem disorders that carry a markedly increased risk of developing myeloid malignancies with somatic monosomy 7. Here, we describe 16 siblings, the majority of which were phenotypically normal, from 5 families diagnosed with myelodysplasia and leukemia syndrome with monosomy 7 (MLSM7; OMIM 252270) who primarily had onset of hematologic abnormalities during the first decade of life. Molecular analyses uncovered germline SAMD9L (n = 4) or SAMD9 (n = 1) mutations in these families. Affected individuals had a highly variable clinical course that ranged from mild and transient dyspoietic changes in the bone marrow to a rapid progression of myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML) with monosomy 7. Expression of these gain-of-function SAMD9 and SAMD9L mutations reduces cell cycle progression, and deep sequencing demonstrated selective pressure favoring the outgrowth of clones that have either lost the mutant allele or acquired revertant mutations. The myeloid malignancies of affected siblings acquired cooperating mutations in genes that are also altered in sporadic cases of AML characterized by monosomy 7. These data have implications for understanding how SAMD9 and SAMD9L mutations contribute to myeloid transformation and for recognizing, counseling, and treating affected families.
- Published
- 2018
29. Transient THz conductivity of silicon with optical pumping above and below the second indirect transition
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Novelli, Fabio and Davis, Jeffrey A
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Physics - Optics ,Condensed Matter - Other Condensed Matter ,Condensed Matter - Strongly Correlated Electrons - Abstract
Here we perform a series of time-resolved experiments where a 100 fs pump pulse is tuned between 528 nm and 555 nm, across the second indirect gap of intrinsic silicon at ~540 nm which involves electrons in a higher-lying conduction band with minimum at the L point. The photo-injected carriers, after inter- and intra-band relaxations are complete, are subsequently probed with high-field single-cycle terahertz radiation. When the energy of the pump pulses exceeds the second indirect gap, the probed terahertz absorption decreases by a factor 2.7$\pm$0.2. We suggest that this dramatic change could be due to the different phonon populations obtained when the carriers undergo the L to X inter-band scattering, instead of just cooling within the X-valley.
- Published
- 2016
30. Separating Pathways in Double-Quantum Optical Spectroscopy Reveals Excitonic Interactions
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Tollerud, Jonathan and Davis, Jeffrey
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Physics - Optics - Abstract
Techniques for coherent multidimensional optical spectroscopy have been developed and utilised to understand many different processes, including energy transfer in photosynthesis and many-body effects in semiconductor nanostructures. Double-quantum 2D spectroscopy is one variation that has been particularly useful for understanding many-body effects. In condensed matter systems, however, there are often many competing signal pathways, which can make it difficult to isolate different contributions and retrieve quantitative information. Here, a means of separating overlapping pathways while maintaining the fidelity of the relevant peak/s is demonstrated. This selective approach is used to isolate the double-quantum signal from a mixed two exciton state in a semiconductor quantum well. The removal of overlapping peaks allows analysis of the relevant peak-shape and thus details of interactions with the environment and other carriers to be revealed. An alternative pulse ordering identifies a double-quantum state associated only with GaAs defects, the signature of which has previously been confused with other interaction induced effects. The experimental approach described here provides access to otherwise hidden details of excitonic interactions and demonstrates that the manner in which the double-quantum coherence is generated can be important and provide an additional control to help understand the many-body physics in complex systems.
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- 2016
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31. Revealing and Characterizing Dark Excitons Through Coherent Multidimensional Spectroscopy
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Tollerud, Jonathan O., Cundiff, Steven T., and Davis, Jeffrey A.
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Physics - Optics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science ,Condensed Matter - Other Condensed Matter - Abstract
Dark excitons are of fundamental importance in a broad range of contexts, but are difficult to study using conventional optical spectroscopy due to their weak interaction with light. We show how coherent multidimensional spectroscopy can reveal and characterize dark states. Using this approach, we identify different types of dark excitons in InGaAs/GaAs quantum wells and determine details regarding lifetimes, homogeneous and inhomogeneous linewidths, broadening mechanisms and coupling strengths. The observations of coherent coupling between bright and dark excitons hint at a role for a multi-step process by which excitons in the barrier can relax into the quantum wells.
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- 2016
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32. Two-dimensional double-quantum spectroscopy: peak shapes as a sensitive probe of carrier interactions in quantum wells
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Tollerud, Jonathan O. and Davis, Jeffrey A.
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Physics - Optics ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We identify carrier scattering at densities below which it has previously been observed in semiconductor quantum wells. These effects are evident in the peakshapes of 2D double-quantum spectra, which change as a function of excitation density. At high excitation densities ($\geq 10^{9}$ carriers/,cm$^{-2}$) we observe untilted peaks similar to those reported in previous experiments. At low excitation densities (<$10^{8}$ carriers cm$^{-2}$) we observe narrower, tilted peaks. Using a simple simulation, we show that tilted peak-shapes are expected in double-quantum spectra when inhomogeneous broadening is much larger than homogeneous broadening, and that fast pure-decoherence of the double-quantum coherence can obscure this peak tilt. These results show that carrier interactions are important at lower densities than previously expected, and that the `natural' double-quantum peakshapes are hidden by carrier interactions at the excitation densities typically used. Furthermore, these results demonstrate that analysis of 2D peak-shapes in double-quantum spectroscopy provides an incisive tool for identifying interactions at low excitation density.
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- 2016
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33. The Effects of Brownian Motion On Particle Interactions with Patchy Surfaces Bearing Nanoscale Features
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Bendersky, Marina, Santore, Maria M., and Davis, Jeffrey M.
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Condensed Matter - Soft Condensed Matter - Abstract
The effects of Brownian motion on particle interactions with heterogeneous collectors are evaluated by adding stochastic Brownian displacements to the particle trajectories and comparing those trajectories to those where Brownian motion is not included. We define adhesion thresholds as the average patch density on the collector required to adhere colloidal particles and P\'{e}clet numbers that quantify the relative importance of colloidal, shear and Brownian effects. We show that Brownian motion has a negligible influence on particle trajectories over collectors patterned with nano-scale heterogeneity, the non-uniform distribution of which creates locally attractive and repulsive areas within the collector. High energy barriers in strong locally repulsive areas cannot be overcome by Brownian motion, such that particle deposition on patchy collectors is controlled by spatially varying DLVO interactions and not by Brownian motion. The overall adhesive behavior of the system remains unaffected by the introduction of Brownian motion effects in the simulations, and therefore, for particle sizes that are usually used in experiments of particle trajectories over nanoscale heterogeneous collectors, it is reasonable to neglect Brownian motion effects entirely., Comment: 8 pages, 6 figures
- Published
- 2015
34. Effect of soybean variety and systemic induction on herbivore feeding guilds
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Dryburgh, John L. and Davis, Jeffrey A.
- Published
- 2021
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35. Counting prime juggling patterns
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Banaian, Esther, Butler, Steve, Cox, Christopher, Davis, Jeffrey, Landgraf, Jacob, and Ponce, Scarlitte
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Mathematics - Combinatorics - Abstract
Juggling patterns can be described by a closed walk in a (directed) state graph, where each vertex (or state) is a landing pattern for the balls and directed edges connect states that can occur consecutively. The number of such patterns of length $n$ is well known, but a long-standing problem is to count the number of prime juggling patterns (those juggling patterns corresponding to cycles in the state graph). For the case of $b=2$ balls we give an expression for the number of prime juggling patterns of length $n$ by establishing a connection with partitions of $n$ into distinct parts. From this we show the number of two-ball prime juggling patterns of length $n$ is $(\gamma-o(1))2^n$ where $\gamma=1.32963879259...$. For larger $b$ we show there are at least $b^{n-1}$ prime cycles of length $n$.
- Published
- 2015
36. A generalization of Eulerian numbers via rook placements
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Banaian, Esther, Butler, Steve, Cox, Christopher, Davis, Jeffrey, Landgraf, Jacob, and Ponce, Scarlitte
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Mathematics - Combinatorics ,05A15, 05A10 - Abstract
We consider a generalization of Eulerian numbers which count the number of placements of $cn$ "rooks" on an $n\times n$ board where there are exactly $c$ rooks in each row and each column, and exactly $k$ rooks below the main diagonal. The standard Eulerian numbers correspond to the case $c=1$. We show that for any $c$ the resulting numbers are symmetric and give generating functions of these numbers for small values of $k$., Comment: 15 pages
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- 2015
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37. A computational study of chemically heterogeneous particles: patchy vs. uniform particles in shear flow
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Bendersky, Marina, Santore, Maria M., and Davis, Jeffrey M.
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Condensed Matter - Soft Condensed Matter - Abstract
The adhesion of flowing particles and biological cells over fixed collecting surfaces is vitally important in diverse situations and potentially controlled by small-scale surface heterogeneity on the particle. Differences in the behavior of patchy particles (flowing over uniform collectors) relative to the reverse case of uniform particles (flowing over patchy collectors) are quantified. Because a particle rotates more slowly than it translates in the shear field near a collecting surface, the effective interaction time of a patch on a particle is larger than that of a patch on the collector, suggesting distinct particle capture tendencies in each case. This paper presents a new computational approach to simulate the near-surface motion (rotation and translation) of particles having nanoscale surface heterogeneities flowing over uniform collectors. Small amounts of ~10 nm cationic patches randomly distributed on a net-negative particle surface produced spatially varying DLVO interactions that were computed via the Grid Surface Integration (GSI) technique and then combined with hydrodynamic forces in a mobility tensor formulation. Statistical analysis of simulated trajectories revealed fewer extrema in the fluctuating particle-collector separation of heterogeneous particles, compared with the reverse system geometry of uniform particles flowing past a heterogeneous fixed surface. Additionally, the patchy particles were captured to a lesser extent on uniform surfaces compared with the case of uniform particles flowing above patchy collectors. Such behavior was dependent on ionic strength, with the greatest differences obtained near a Debye length of $\kappa^{-1} = 4$ nm for the $2a = 500$ nm simulated particles.
- Published
- 2015
38. Vibronic resonances facilitate excited state coherence in light harvesting proteins at room temperature
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Novelli, Fabio, Nazir, Ahsan, Richards, Gethin H., Roozbeh, Ashkan, Wilk, Krystyna E., Curmi, Paul M. G., and Davis, Jeffrey A.
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Physics - Biological Physics ,Physics - Chemical Physics ,Physics - Optics ,Quantum Physics - Abstract
Until recently it was believed that photosynthesis, a fundamental process for life on earth, could be fully understood with semi-classical models. However, puzzling quantum phenomena have been observed in several photosynthetic pigment-protein complexes, prompting questions regarding the nature and role of these effects. Recent attention has focused on discrete vibrational modes that are resonant or quasi-resonant with excitonic energy splittings and strongly coupled to these excitonic states. Here we unambiguously identify excited state coherent superpositions in photosynthetic light-harvesting complexes using a new experimental approach. Decoherence on the timescale of the excited state lifetime allows low energy (56 cm-1) oscillations on the signal intensity to be observed. In conjunction with an appropriate model, these oscillations provide clear and direct experimental evidence that the persistent coherences observed require strong vibronic mixing among excited states.
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- 2015
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39. Successful Pressing Sequences for a Bicolored Graph and Binary Matrices
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Cooper, Joshua and Davis, Jeffrey
- Subjects
Mathematics - Combinatorics ,05C50, 15B33, 92D15 - Abstract
We apply matrix theory over $\mathbb{F}_2$ to understand the nature of so-called "successful pressing sequences" of black-and-white vertex-colored graphs. These sequences arise in computational phylogenetics, where, by a celebrated result of Hannenhalli and Pevzner, the space of sortings-by-reversal of a signed permutation can be described by pressing sequences. In particular, we offer several alternative linear-algebraic and graph-theoretic characterizations of successful pressing sequences, describe the relation between such sequences, and provide bounds on the number of them. We also offer several open problems that arose as a result of the present work.
- Published
- 2015
40. Bifurcation in a thin liquid film flowing over a locally heated surface
- Author
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Katkar, Harshwardhan H. and Davis, Jeffrey M.
- Subjects
Physics - Fluid Dynamics - Abstract
We investigate the non-linear dynamics of a two-dimensional film flowing down a finite heater, for a non-volatile and a volatile liquid. An oscillatory instability is predicted beyond a critical value of Marangoni number using linear stability theory. Continuation along the Marangoni number using non-linear evolution equation is used to trace bifurcation diagram associated with the oscillatory instability. Hysteresis, a characteristic attribute of a sub-critical Hopf bifurcation, is observed in a critical parametric region. The bifurcation is universally observed for both, a non-volatile film and a volatile film., Comment: Revised manuscript published at http://dx.doi.org/10.1017/jfm.2013.245
- Published
- 2014
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41. Disentangling electronic and vibrational coherence in the Phycocyanin-645 light-harvesting complex
- Author
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Richards, Gethin H., Wilk, Krystyna E., Curmi, Paul M. G., and Davis, Jeffrey A.
- Subjects
Physics - Chemical Physics ,Physics - Biological Physics ,Physics - Optics - Abstract
Energy transfer between chromophores in photosynthesis proceeds with near unity quantum efficiency. Understanding the precise mechanisms of these processes is made difficult by the complexity of the electronic structure and interactions with different vibrational modes. Two-dimensional spectroscopy has helped resolve some of the ambiguities and identified quantum effects that may be important for highly efficient energy transfer. Many questions remain, however, including whether the coherences observed are electronic and/or vibrational in nature and what role they play. We utilise a two-colour four-wave mixing experiment with control of the wavelength and polarization to selectively excite specific coherence pathways. For the light-harvesting complex PC645, from cryptophyte algae, we reveal and identify specific contributions from both electronic and vibrational coherences and determine an excited state structure based on two strongly-coupled electronic states and two vibrational modes. Separation of the coherence pathways also uncovers the complex evolution of these coherences and the states involved.
- Published
- 2013
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42. Isolating quantum coherence with pathway-selective coherent multi-dimensional spectroscopy
- Author
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Tollerud, Jonathan O, Hall, Christopher R, and Davis, Jeffrey A
- Subjects
Physics - Optics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Physics - Chemical Physics - Abstract
Coherent coupling between spatially separated systems has long been explored as a necessary requirement for quantum information and cryptography. Recent discoveries suggest such phenomena appear in a much wider range of processes, including light-harvesting in photosynthesis. These discoveries have been facilitated by developments in coherent multi-dimensional spectroscopy (CMDS) that allow interactions between different electronic states to be identified in crowded spectra. For complex systems, however, spectral broadening and multiple overlapping peaks limit the ability to separate, identify and properly analyse all contributions. Here we demonstrate how pathway-selective CMDS can overcome these limitations to reveal, isolate and allow detailed analysis of weak coherent coupling between spatially separated excitons localised to different semiconductor quantum wells. Selective excitation of the coherence pathways, by spectrally shaping the laser pulses, provides access to previously hidden details and enables quantitative analysis that can facilitate precise and detailed understanding of interactions in this and other complex systems.
- Published
- 2013
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43. Simple method to evaluate the pixel crosstalk caused by fringing field effect in liquid-crystal spatial light modulators
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Moreno, Ignacio, Sánchez-López, María Del Mar, Davis, Jeffrey A., and Cottrell, Don M.
- Published
- 2021
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44. Identification of compound causing yellow bone discoloration following alpha-glycosyl isoquercitrin exposure in Sprague–Dawley rats
- Author
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Davis, Jeffrey P., Koyanagi, Mihoko, Maronpot, Robert R., Recio, Leslie, and Hayashi, Shim-mo
- Published
- 2020
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45. Regenerative water sources on surfaces of airless bodies
- Author
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Zhu, Cheng, Góbi, Sándor, Abplanalp, Matthew J., Frigge, Robert, Gillis-Davis, Jeffrey J., Dominguez, Gerardo, Miljković, Katarina, and Kaiser, Ralf I.
- Published
- 2020
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46. Host preference of sweetpotato weevil, Cylas formicarius elegantulus (Summers): an example of Hopkins’ host-selection principle
- Author
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Chen, Jie, Stout, Michael J., Beuzelin, Julien, Smith, Tara P., LaBonte, Don, Murray, Jeff M., and Davis, Jeffrey A.
- Published
- 2019
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47. Outcomes after Hematopoietic Stem Cell Transplantation for Children with I-Cell Disease
- Author
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Lund, Troy C, Cathey, Sara S, Miller, Weston P, Eapen, Mary, Andreansky, Martin, Dvorak, Christopher C, Davis, Jeffrey H, Dalal, Jignesh D, Devine, Steven M, Eames, Gretchen M, Ferguson, William S, Giller, Roger H, He, Wensheng, Kurtzberg, Joanne, Krance, Robert, Katsanis, Emmanuel, Lewis, Victor A, Sahdev, Indira, and Orchard, Paul J
- Subjects
Biomedical and Clinical Sciences ,Cardiovascular Medicine and Haematology ,Stem Cell Research - Nonembryonic - Non-Human ,Stem Cell Research ,Stem Cell Research - Nonembryonic - Human ,Pediatric ,Regenerative Medicine ,Transplantation ,Development of treatments and therapeutic interventions ,5.2 Cellular and gene therapies ,Good Health and Well Being ,Child ,Preschool ,Data Collection ,Hematopoietic Stem Cell Transplantation ,Humans ,Infant ,Mucolipidoses ,Surveys and Questionnaires ,Transplantation Conditioning ,Treatment Outcome ,I-cell disease ,Mucolipidosis type II ,Hematopoietic stem cell transplant ,Lysosomal storage disease ,Clinical Sciences ,Immunology ,Cardiovascular medicine and haematology - Abstract
Mucolipidosis type II (MLII), or I-cell disease, is a rare but severe disorder affecting localization of enzymes to the lysosome, generally resulting in death before the 10th birthday. Although hematopoietic stem cell transplantation (HSCT) has been used to successfully treat some lysosomal storage diseases, only 2 cases have been reported on the use of HSCT to treat MLII. For the first time, we describe the combined international experience in the use of HSCT for MLII in 22 patients. Although 95% of the patients engrafted, overall survival was low, with only 6 patients (27%) alive at last follow-up. The most common cause of death post-transplant was cardiovascular complications, most likely due to disease progression. Survivors were globally delayed in development and often required complex medical support, such as gastrostomy tubes for nutrition and tracheostomy with mechanical ventilation. Although HSCT has demonstrated efficacy in treating some lysosomal storage disorders, the neurologic outcome and survival for patents with MLII were poor. Therefore, new medical and cellular therapies should be sought for these patients.
- Published
- 2014
48. Comparison of outcomes of hematopoietic stem cell transplantation without chemotherapy conditioning by using matched sibling and unrelated donors for treatment of severe combined immunodeficiency
- Author
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Dvorak, Christopher C, Hassan, Amel, Slatter, Mary A, Hönig, Manfred, Lankester, Arjan C, Buckley, Rebecca H, Pulsipher, Michael A, Davis, Jeffrey H, Güngör, Tayfun, Gabriel, Melissa, Bleesing, Jacob H, Bunin, Nancy, Sedlacek, Petr, Connelly, James A, Crawford, David F, Notarangelo, Luigi D, Pai, Sung-Yun, Hassid, Jake, Veys, Paul, Gennery, Andrew R, and Cowan, Morton J
- Subjects
Biomedical and Clinical Sciences ,Cardiovascular Medicine and Haematology ,Transplantation ,Cancer ,Regenerative Medicine ,Hematology ,Clinical Research ,Stem Cell Research - Nonembryonic - Human ,Stem Cell Research ,Adult ,Australia ,B-Lymphocytes ,Child ,Chimerism ,Europe ,Female ,Graft vs Host Disease ,Hematopoietic Stem Cell Transplantation ,Histocompatibility ,Histocompatibility Testing ,Humans ,Infant ,Infant ,Newborn ,Male ,North America ,Retrospective Studies ,Severe Combined Immunodeficiency ,Siblings ,Survival Analysis ,T-Lymphocytes ,Transplantation Conditioning ,Treatment Outcome ,Unrelated Donors ,Volunteers ,Severe combined immunodeficiency ,hematopoietic cell transplantation ,sibling donors ,unrelated donors ,umbilical cord blood ,conditioning ,serotherapy ,Conditioning ,Hematopoietic cell transplantation ,Serotherapy ,Sibling donors ,Umbilical cord blood ,Unrelated donors ,Immunology ,Allergy - Abstract
BackgroundPatients with severe combined immunodeficiency disease who have matched sibling donors (MSDs) can proceed to hematopoietic cell transplantation (HCT) without conditioning chemotherapy.ObjectiveWe sought to determine whether the results of HCT without chemotherapy-based conditioning from matched unrelated donors (URDs), either from volunteer adults or umbilical cord blood, are comparable with those from MSDs.MethodsWe performed a multicenter survey of severe combined immunodeficiency transplantation centers in North America, Europe, and Australia to compile retrospective data on patients who have undergone unconditioned HCT from either URDs (n = 37) or MSDs (n = 66).ResultsMost patients undergoing URD HCT (92%) achieved donor T-cell engraftment compared with 97% for those with MSDs; however, estimated 5-year overall and event-free survival were worse for URD recipients (71% and 60%, respectively) compared with MSD recipients (92% and 89%, respectively; P < .01 for both). URD recipients who received pre-HCT serotherapy had similar 5-year overall survival (100%) to MSD recipients. The incidences of grade II to IV acute and chronic graft-versus-host disease were higher in URD (50% and 39%, respectively) compared with MSD (22% and 5%, respectively) recipients (P < .01 for both). In the surviving patients there was no difference in T-cell reconstitution at the last follow-up between the URD and MSD recipients; however, MSD recipients were more likely to achieve B-cell reconstitution (72% vs 17%, P < .001).ConclusionUnconditioned URD HCT achieves excellent rates of donor T-cell engraftment similar to that seen in MSD recipients, and reconstitution rates are adequate. However, only a minority will have myeloid and B-cell reconstitution, and attention must be paid to graft-versus-host disease prophylaxis. This approach might be safer in children ineligible for intense regimens to spare the potential complications of chemotherapy.
- Published
- 2014
49. Transplantation outcomes for severe combined immunodeficiency, 2000-2009.
- Author
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Pai, Sung-Yun, Logan, Brent R, Griffith, Linda M, Buckley, Rebecca H, Parrott, Roberta E, Dvorak, Christopher C, Kapoor, Neena, Hanson, Imelda C, Filipovich, Alexandra H, Jyonouchi, Soma, Sullivan, Kathleen E, Small, Trudy N, Burroughs, Lauri, Skoda-Smith, Suzanne, Haight, Ann E, Grizzle, Audrey, Pulsipher, Michael A, Chan, Ka Wah, Fuleihan, Ramsay L, Haddad, Elie, Loechelt, Brett, Aquino, Victor M, Gillio, Alfred, Davis, Jeffrey, Knutsen, Alan, Smith, Angela R, Moore, Theodore B, Schroeder, Marlis L, Goldman, Frederick D, Connelly, James A, Porteus, Matthew H, Xiang, Qun, Shearer, William T, Fleisher, Thomas A, Kohn, Donald B, Puck, Jennifer M, Notarangelo, Luigi D, Cowan, Morton J, and O'Reilly, Richard J
- Subjects
T-Lymphocytes ,Humans ,Severe Combined Immunodeficiency ,Graft vs Host Disease ,Immunoglobulin A ,Lymphocyte Count ,Treatment Outcome ,Transplantation Conditioning ,Retreatment ,Hematopoietic Stem Cell Transplantation ,Incidence ,Survival Rate ,Retrospective Studies ,Siblings ,Infant ,Female ,Male ,CD3 Complex ,Clinical Research ,Organ Transplantation ,Regenerative Medicine ,Transplantation ,Rare Diseases ,Pediatric ,Orphan Drug ,Good Health and Well Being ,Medical and Health Sciences ,General & Internal Medicine - Abstract
BackgroundThe Primary Immune Deficiency Treatment Consortium was formed to analyze the results of hematopoietic-cell transplantation in children with severe combined immunodeficiency (SCID) and other primary immunodeficiencies. Factors associated with a good transplantation outcome need to be identified in order to design safer and more effective curative therapy, particularly for children with SCID diagnosed at birth.MethodsWe collected data retrospectively from 240 infants with SCID who had received transplants at 25 centers during a 10-year period (2000 through 2009).ResultsSurvival at 5 years, freedom from immunoglobulin substitution, and CD3+ T-cell and IgA recovery were more likely among recipients of grafts from matched sibling donors than among recipients of grafts from alternative donors. However, the survival rate was high regardless of donor type among infants who received transplants at 3.5 months of age or younger (94%) and among older infants without prior infection (90%) or with infection that had resolved (82%). Among actively infected infants without a matched sibling donor, survival was best among recipients of haploidentical T-cell-depleted transplants in the absence of any pretransplantation conditioning. Among survivors, reduced-intensity or myeloablative pretransplantation conditioning was associated with an increased likelihood of a CD3+ T-cell count of more than 1000 per cubic millimeter, freedom from immunoglobulin substitution, and IgA recovery but did not significantly affect CD4+ T-cell recovery or recovery of phytohemagglutinin-induced T-cell proliferation. The genetic subtype of SCID affected the quality of CD3+ T-cell recovery but not survival.ConclusionsTransplants from donors other than matched siblings were associated with excellent survival among infants with SCID identified before the onset of infection. All available graft sources are expected to lead to excellent survival among asymptomatic infants. (Funded by the National Institute of Allergy and Infectious Diseases and others.).
- Published
- 2014
50. Non-mumps Viral Parotitis During the 2014–2015 Influenza Season in the United States
- Author
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Elbadawi, Lina I., Talley, Pamela, Rolfes, Melissa A., Millman, Alexander J., Reisdorf, Erik, Kramer, Natalie A., Barnes, John R., Blanton, Lenee, Christensen, Jaime, Cole, Stefanie, Danz, Tonya, Dreisig, John J., Garten, Rebecca, Haupt, Thomas, Isaac, Beth M., Jackson, Mary Anne, Kocharian, Anna, Leifer, Daniel, Martin, Karen, McHugh, Lisa, McNall, Rebecca J., Palm, Jennifer, Radford, Kay W., Robinson, Sara, Rosen, Jennifer B., Sakthivel, Senthilkumar K., Shult, Peter, Strain, Anna K., Turabelidze, George, Webber, Lori A., Weinberg, Meghan Pearce, Wentworth, David E., Whitaker, Brett L., Finelli, Lyn, Jhung, Michael A., Lynfield, Ruth, and Davis, Jeffrey P.
- Published
- 2018
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