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Cryptography is the practice of secure communication and the study of secure communication techniques. The theoretical foundations of cryptography include concepts such as cryptography, secure key exchange, digital signatures, and authentication. These technologies are used to protect the confidentiality, integrity, and reliability of information while it is being transmitted over a network or stored in digital form. The core of encryption is the concept of an encryption algorithm, which is a set of mathematical rules used to encrypt and decrypt data. The security of a cryptographic system depends on the strength of the underlying algorithm and the confidentiality of the key used to encrypt and decrypt the data. In this paper, Cryptography concepts and modern techniques are reviewed for types of encryption algorithms and the best ones, and many types of attacks and their impact on the encryption process

Ultraviolet (UV) radiation falls between visible light and X-rays (100–400 nm) in the electromagnetic spectrum. UVA, UVB, and UVC are the three sub-regions of the ultraviolet spectrum., with UVC reported most effective against microorganisms. Depending on the microorganism's form, UV has a different effect on microbes, having a greater effect on vegetative cells possessing short contact time, while spore-forming organisms are more resistant to UV. Yeast has also been reported to survive UV radiation better than other organisms. UV light makes microorganisms dormant by forming pyrimidine dimers in RNA and DNA, which prevent replication and transcription. Impact of UV light on microorganisms is dependent on microbial exposure and the environment the organisms exist in. Evaluating the impacts of ultraviolet radiation on different species of microbes can help in the prevention of contamination and spread of infectious organisms. There are limited reviews on the effects of ultraviolet radiation on microbes. This review will therefore analyse the effects of UV on viruses, bacteria and fungi which are the most common types of microbes.

A key role of chromatin kinases is to phosphorylate histone tails during mitosis to spatiotemporally regulate cell division. Vaccinia-related kinase 1 (VRK1) is a serine–threonine kinase that phosphorylates histone H3 threonine 3 (H3T3) along with other chromatin-based targets. While structural studies have defined how several classes of histone-modifying enzymes bind to and function on nucleosomes, the mechanism of chromatin engagement by kinases is largely unclear. Here, we paired cryo-electron microscopy with biochemical and cellular assays to demonstrate that VRK1 interacts with both linker DNA and the nucleosome acidic patch to phosphorylate H3T3. Acidic patch binding by VRK1 is mediated by an arginine-rich flexible C-terminal tail. Homozygous missense and nonsense mutations of this acidic patch recognition motif in VRK1 are causative in rare adult-onset distal spinal muscular atrophy. We show that these VRK1 mutations interfere with nucleosome acidic patch binding, leading to mislocalization of VRK1 during mitosis, thus providing a potential new molecular mechanism for pathogenesis.

The nuclear shell model with modified surface delta interaction MSDI was used to calculate the values of energy levels of the copper nucleus 58Cu. The neutron and proton in the model space 1p3/2 0f5/2 1p1/2 of the copper nucleus occur outside the closed core 56Ni. This research investigates the excitation energy and angular momentum. As a consequence, theoretical approaches are used to uncover a collection between excitation energies and classical coupling angles θa,b at various orbitals. Finally, we demonstrate that our results are supported by experimental evidence: Excitation energies have two major functions, both of which are influenced by classical coupling angles but are unaffected by angular momentum I.

Listeriosis is one of the most common foodborne diseases caused by Listeria monocytogenes (L. monocytogenes). A poor prognosis has been recorded for the invasive listeriosis, especially neurolisteriosis. In several countries throughout the world, foodborne infections with L. monocytogenes exceeded the legal safety limits in animal sourced foods. Therefore, we decided to investigate the variability, virulence and antimicrobial resistance profiles of this pathogen. Both phenotypic and genotypic methods were used for identifying L. monocytogenes isolates and confirming their virulence profiles. The antimicrobial resistances and their correlation analysis with the existence of virulence genes were detected. Additionally, sequencing and phylogenetic analysis based on L. monocytogenes inlA and inlB genes were undertaken. The prevalence rate (11.9%) and the resistance profiles of L. monocytogenes were shocking. The multi-drug resistance (MDR) phenotypes were common among our isolates (64.9%). Fortunately, the resistance phenotypes were always associated with low virulence arrays and the MDR strains possessed low virulence fitness. Herein, the high genotypic and phenotypic diversity of L. monocytogenes isolates and their weak clonality and adaptability highlighted the difficulty in controlling and managing this pathogen. Therefore, it is important to add more restriction guidelines from national authorities on the consumption of ready to eat foods.

Bio-functionalized metal oxide nanoparticles (NPs) have been taken great importance in biomedical fields. The use of nanoparticles as delivery agents of therapeutic molecules led the researchers to emphasize the potential impact of these NPs on bio-macromolecules as protein-nanoparticle complexes, which also extended their importance as vehicles in targeted drug delivery systems due to increased ease of administration, firmness, reduced toxic side effects, and half-life of drugs. Since human serum albumin is the blood protein responsible for transporting materials in the blood system, the interaction of these particles with HSA is essential to be understood before considering the nanoparticles for any individual biomedical application. In the present study, we synthesized zinc-oxide nanorods (ZONRs) using a microwave-assisted synthesis technique, and characterized them by XRD, FTIR, Raman, SEM-EDX, UV-Vis spectroscopy, and photoluminescence (PL) spectroscopy methods. The interaction studies were carried out using fluorescence spectroscopy, and the change in secondary structure was analyzed using CD spectroscopy. The results of MTT cell viability assay demonstrated that the ZONRs has potential cytotoxic properties.

Listeriosis is one of the most common foodborne diseases caused by

Michael A Fishman,1 Ajay B Antony,2 Corey W Hunter,3 Jason E Pope,4 Peter S Staats,5 Rahul Agarwal,6 Allison T Connolly,6 Nirav Dalal,6 Timothy R Deer7 1Center for Interventional Pain and Spine, Exton, PA, USA; 2The Orthopaedic Institute, Gainesville, FL, USA; 3Ainsworth Institute of Pain Management, New York, NY, USA; 4Evolve Restorative Center, Santa Rosa, CA, USA; 5Premier Pain Centers, Shrewsbury, NJ, USA; 6Abbott, Sylmar, CA, USA; 7The Spine and Nerve Center of the Virginias, Charleston, WV, USACorrespondence: Michael A FishmanCenter for Interventional Pain and Spine, 160 North Pointe Blvd Suite 208, Lancaster, PA, 17603, USATel +1 917-543-6588Email mafishman@gmail.comBackground and Aims: Chronic pain affects more adults in the United States than any other condition. Opioid medications are widely used in the treatment of chronic pain, but there remains considerable risk and cost associated with their use. This study aims to characterize the effects of opioid prescribing for chronic pain and similar pain conditions on lost productivity in the United States.Methods: This was a retrospective, longitudinal, observational study of chronic pain patients in 2011– 2014. We identified patients with a diagnosis of musculoskeletal pain receiving index prescription for opioids in administrative claims and studied disability absence in a linked health and productivity management database. Patients were grouped as de novo and continued use opioid users before index, and by opioid dose in the year after index. Days of disability were compared before and after index with bootstrapping. Effect of opioid dose group on disability was evaluated with negative binomial regression. Lost productivity cost was compared before and after index.Results: The cohort contained 16,273 de novo and 6604 continued use patients. On average, de novo patients used 24.8 days of disability after index, an increase of 18.3 more days compared to before (p < 0.001). Continued use patients used 30.7 days after index, 9 more days than before (p < 0.001). There was a dose–response relationship between dose group and days of disability in de novo patients (p < 0.001). The weighted-average cost per person of lost productivity was $4344 higher in the year after index compared to the year before.Conclusion: Opioid prescriptions for pain patients were associated with significant disability use and lost productivity costs. With the evolution of opioid-prescribing practices, CDC recommendations, and the HHS Pain Management Best Practices, there is opportunity to use alternative pain therapies without the risks of opioid-induced side effects to improve work productivity.Keywords: opioids, pain, disability, productivity

Quantitative analysis of chromatin protein-nucleosome interactions is essential to understand regulation of genome-templated processes. However, current methods to measure nucleosome interactions are limited by low throughput, low signal-to-noise, and/or the requirement for specialized instrumentation. Here, we report a Lanthanide Chelate Excite Time-Resolved Fluorescence Resonance Energy Transfer (LANCE TR-FRET) assay to efficiently quantify chromatin protein-nucleosome interactions. The system makes use of commercially available reagents, offers robust signal-to-noise with minimal sample requirements, uses a conventional fluorescence microplate reader, and can be adapted for high-throughput workflows. We determined the nucleosome-binding affinities of several chromatin proteins and complexes, which are consistent with measurements obtained through orthogonal biophysical methods. We also developed a TR-FRET competition assay for high-resolution footprinting of chromatin protein-nucleosome interactions. Finally, we set up a TR-FRET competition assay using the LANA peptide to quantitate nucleosome acidic patch binding. We applied this assay to establish a proof-of-principle for regulation of nucleosome acidic patch binding by methylation of chromatin protein arginine anchors. Overall, our TR-FRET assays allow facile, high-throughput quantification of chromatin interactions and are poised to complement mechanistic chromatin biochemistry, structural biology, and drug discovery programs.

Noble metals gold NPs are produced by pulsed (“Q-switched, 1064 nm Nd: YAG”) ablation of gold foil dipped in doubles distilled water DDW by laser. (PLAL) the process was performed with laser energy in range (400–700) mJ at (90 pulses, wavelength 1064 and room temperature and liquid depth 9 mm. The influence of laser energies have been tested structurally, optically and morphologically and examined by using scanning electron microscope (SEM), UV-visible spectroscopy and atomic force microscope (AFM). The absorption spectra of AuNPs are prepared in water piercing and solitary peaks nearby 518 and 524 nm, demonstrating the assembly of clean and sphericals in shape AuNPs with the middling size in the range of (20–50) nm. SEM and AFM have established all the measurements of size.

In this study, we report on a successful preparation nanocomposites poly (o-toluidine) (POT) doping with dodecylbenzene sulfonate acid (DBSA)/ ZnO by in-situ polymerization of (o-toluidine) monomer using ZnO nanoparticles (the weight ratios OT/ZnO: 1/5%, 1/10%, 1/15%). The composite films have been prepared by using the casting method on different substrate depending on the type of measurement. The surface morphology properties of the prepared samples were studied by the field emission scanning electron microscopy (FESEM). The results of FESEM indicate that ZnO nanoparticles were successfully embedded in the POT via chemical interactions between ZnO and (O-toluidine) monomer and the EDX spectrum showed the presence of element Zn in POT-DBSA/ZnO composites. The crystal structure was measured by x-ray directional and its pattern revealed the presence of ZnO in dopant polymer, in the diffraction patterns of POT-DBSA. The intensity of the peaks was increased as the amount of ZnO nanoparticles increased in POT-DBSA. The typical rectifying behaviour indicated that the formation of a diode observes by the I–V characterization of POT-DBSA/ZnO composites at thin film layer with top Al thin layer contact.

Metabolic syndrome (MetS) is a serious health condition that is becoming extremely threatening in Saudi Arabia. The link between vitamin D receptor (VDR) gene polymorphisms and maternal MetS has been observed in several ethnic groups, but is yet to be clarified in the Arabian population. This study aims to investigate the relationship between the FokI VDR genotype and the risk of MetS and its components in pregnant Saudi women. A cross-sectional study was conducted using 368 pregnant Saudi women on first trimester screened for MetS (44 with MetS and 324 without MetS). Measurements included anthropometrics, glycemic and lipid profile and 25(OH)D. TaqMan genotyping assay was used to determine Fokl VDR genotype of participants. Vitamin D deficiency (25(OH)D FokI VDR genotyping frequencies for FF, Ff, and ff genotypes were 50%, 36.4% and 13.6%, respectively. In controls, the frequencies were 62.7%, 31.4% and 5.9%, respectively. No significant association between the individual MetS components and FokI VDR genotypes were observed. Nevertheless, carriers of the ff allele had a significant risk for full maternal MetS [Odds Ratio 4.2 (95% Confidence Interval 1.4-12.2; adjusted p=0.009). The study suggests that the ff FokI VDR genotype is a genetic marker of maternal MetS in pregnant Arabian women. Prospective studies that include neonatal outcomes may confirm present findings.

The magnetised 51 kton Iron Calorimeter (ICAL) detector proposed to be built at INO is designed with a focus on detecting 1-20 GeV muons. The magnetic field will enable the measurement of the momentum of the $\mu^-$ and $\mu^+$ generated from the charge current interactions of $\nu_\mu$ and $\bar\nu_\mu$ separately within iron in the detector, thus permitting the determination of the neutrino mass ordering/hierarchy, among other important goals of ICAL. Hence it is important to determine the magnetic field as accurately as possible. The mini-ICAL detector is an 85-ton prototype of ICAL, which is operational at Madurai in South India. We describe here the first measurement of the magnetic field in mini-ICAL using Hall sensor PCBs. A set-up developed to calibrate the Hall probe sensors using an electromagnet. The readout system has been designed using an Arduino Nano board for selection of channels of Hall probes mounted on the PCB and to convert the analog voltage to a digital output. The magnetic field has been measured in the small gaps (provided for the purpose) between iron plates in the top layer of mini-ICAL as well as in the air just outside the detector. A precision of better than 3% was obtained, with a sensitivity down to about 0.03 kGauss when measuring the small fringe fields outside the detector., Comment: 13 pages, 17 figures, latex

Unstructured data becomes challenges because in recent years have observed the ability to gather a massive amount of data from annotated documents. This paper interested with Arabic unstructured text analysis. Manipulating unstructured text and converting it into a form understandable by computer is a high-level aim. An important step to achieve this aim is to understand numerical phrases. This paper aims to extract numerical data from Arabic unstructured text in general. This work attempts to recognize numerical characters phrases, analyze them and then convert them into integer values. The inference engine is based on the Arabic linguistic and morphological rules. The applied method encompasses rules of numerical nouns with Arabic morphological rules, in order to achieve high accurate extraction method. Arithmetic operations are applied to convert the numerical phrase into integer value. The proper operation is determined depending on linguistic and morphological rules. It will be shown that applying Arabic linguistic rules together with arithmetic operations succeeded in extracting numerical data from Arabic unstructured text with high accuracy reaches to 100%.

Objective To assess the level of parents knowledge about the emergency management of tooth avulsion in Eastern Province and Riyadh. Methods A cross-sectional study was carried out by means of a questionnaire-based internet survey in which 1201 parents from Eastern Province and Riyadh participated. The questionnaire contained 10 closed-ended questions and was used to assess the knowledge of parents about the emergency management of avulsed teeth in Eastern Province and Riyadh. Chi-square test was used for data analysis. Results In response to closed-ended questions, the statistically significant result was obtained for the history of child dental trauma in which 35% (P=0.04) of parents reported history of dental trauma in their children. These parents were belong to Eastern province (51%) and Riyadh (49%). Furthermore, only 31.3% of the parents were aware of possible storage media for transportation of avulsed tooth while 68.7% (49.5% in Eastern Province and 50.5% in Riyadh) were unaware (P=0.02) of it. Conclusion That the majority of the parents were unaware of emergency management for tooth avulsion in two densely populated regions of Saudi Arabia. Education of parents should be initiated at a national level.

Business environment is becoming more complex which creates a big pressure on organizations to increase the performance and decrease the budget and time. Typical management information system failed to reach decision makers' expectations. In order to adapt to the global changes and support decision makers, organizations may implement different solutions and strategies. One of the solutions is to implement business intelligence (BI) in large organizations. The aim of this chapter is to assess the effectiveness of BI solutions and propose a solution for improving knowledge management using BI and cloud computing. A quantitative research method is used which includes survey and interviews. The results will be analyzed to evaluate the current BI solutions in order to identify the problems of knowledge management and decision-making process. Accordingly, a solution will be proposed to overcome the identified problem using cloud BI.

Unstructured data becomes challenges because in recent years have observed the ability to gather a massive amount of data from annotated documents. This paper interested with Arabic unstructured text analysis. Manipulating unstructured text and converting it into a form understandable by computer is a high-level aim. An important step to achieve this aim is to understand numerical phrases. This paper aims to extract numerical data from Arabic unstructured text in general. This work attempts to recognize numerical characters phrases, analyze them and then convert them into integer values. The inference engine is based on the Arabic linguistic and morphological rules. The applied method encompasses rules of numerical nouns with Arabic morphological rules, in order to achieve high accurate extraction method. Arithmetic operations are applied to convert the numerical phrase into integer value. The proper operation is determined depending on linguistic and morphological rules. It will be shown that applying Arabic linguistic rules together with arithmetic operations succeeded in extracting numerical data from Arabic unstructured text with high accuracy reaches to 100%.

In cryptography, hash functions have very important effects when it’s used in the message integrity, digital time stamping, and digital signature. Hash functions compute hash value by a set of logical (primitive) operations that perform on a (32) bit words for authentication. Authentication process becomes very important especially manipulated message undetected that can have disastrous effects in Network Management and E-Commerce. In this paper, a proposal for new hash function based on MD5 is developed. The length of message digest is 224-bit through (4) rounds that each round has a pair of (16) steps. The final number of steps is (128) that make stronger function against collision attests and more secure than MD5.

Organic/inorganic heterojunction solar cells have been fabricated based on CdSe/PVA nanocomposite as an acceptor and PANI-DBSA/PS nanofibers as a donor material. CdSe/PVA nanocomposite PANI-DBSA/PS nanofiber materials have been prepared by chemical and electrospinning methods, respectively. X-ray diffraction, Atomic Force microscopy and scanning electron microscopy measurements technique reveals that the two nanomaterials have deferent morphology with the crystalline cubic structure of CdSe/PVA nanocomposite and amorphous phase of PANI-DBSA/PS nanofibers. The absorption spectra of PANI-DBSA/PS and CdSe/PVA nanocomposite thin films were analyzed in the wavelength range from 400 nm to 800 nm. the current-voltage density measurements of the solar cell which were performed in the dark and under illumination are reveal that the ideality factor of all the devices is more than one and the maximum power conversion efficiency is 0.3%. The effects of temperature on the photovoltaic properties of solar cells have been investigated. The power conversion efficiency values increased with increasing temperature.

In the present article, new complexes of mononuclear palladium, formed by the interaction of PdCl2 with nicotinamide (nta), picolinic acid (pia), and isonicotinic acid (ina) have been isolated in the solid state with 1:2 M ratio affords the new compounds [Pd(nta)2(Cl)2] (I), [Pd(pia)2] (II), and [Pd(ina)2] (III). The mixed ligand complexes with caffeine (caf) as a secondary ligand have been synthesized and formulated as [Pd(nta)(caf)(Cl)2] (IV), [Pd(pia)(caf)(Cl)] (V), and [Pd(ina)(caf)(Cl)] (VI) with ratio of metal: ligand: ligand is 1:1:1. Structures of these products has been established by elemental analyses, conductivity, FTIR, 1H NMR and thermal analysis data. The shifts of the ν(N–H) amino, ν(C N1) pyridine, ν(C O) carboxylic, and ν(C N9) caffeine stretches have been monitored in order to find out the donor sites of the ligands. According to the experimental data, the six complexes can be characterized in the solid state as mononuclear, with a four-coordinate stereochemistry. SEM, TEM, and XRD analysis determined the characteristics of synthesized nanoparticles. The in vitro antibacterial efficiency of the compounds were evaluated by paper disc diffusion method. Compounds were also screened for their anti-cancer activity against colorectal adenocarcinoma (Caco-2) and breast cancer (Mcf-7) cell lines. This study reveals that [Pd(pia)2] complex has a potent cytotoxic agent against human colorectal adenocarcinoma and breast cancer.

This paper proposed a new method for network self-fault management (NSFM) based on two technologies: intelligent agent to automate fault management tasks, and Windows Management Instrumentations (WMI) to identify the fault faster when resources are independent (different type of devices). The proposed network self-fault management reduced the load of network traffic by reducing the request and response between the server and client, which achieves less downtime for each node in state of fault occurring in the client. The performance of the proposed system is measured by three measures: efficiency, availability, and reliability. A high efficiency average is obtained depending on the faults occurred in the system which reaches to 92.19%, availability 92.375%, and reliability 100%. The proposed system managed five devices. The NSFM implemented using Java and C# languages.

The aim of the current study was to characterize the effects of the novel β-adrenergic antagonist nebivolol on central aortic blood pressures, arterial properties, and nitroxidergic activity in individuals with prehypertension. Prehypertension is emerging as a major risk factor for several adverse cardiovascular consequences. Increased pulse wave velocity, aortic augmentation index, and aortic blood pressures have been linked with augmented risk of cardiovascular disease and mortality. While the effects of antihypertensive drugs on these parameters in hypertensive patients have been studied, there are limited data so far in prehypertension. Fifty individuals with prehypertension were randomized to either nebivolol (5 mg per day) or placebo in a double-blind clinical trial. Patients underwent measurement of pulse wave velocity as well as aortic blood pressure and aortic augmentation index via pulse wave analysis at baseline and 8 weeks. Patients also had blood and urine biochemistries done at each visit. Nebivolol achieved significant reductions in central aortic systolic (P=.011), diastolic (P=.009), and mean arterial blood pressure (P=.002). Pulse wave velocity trended toward improvement but did not achieve significance (P=.088). Nitric oxide production, measured as urinary nitrite/nitrite excretion, also rose substantially in the nebivolol group (by approximately 60%, P=.030). Central blood pressures can be effectively lowered by β-blockade while patients are still in the prehypertension phase, and the effects may be coupled to improve nitric oxide release by the drug.

We study the dynamics of inorganic antiferroelectric nanoclusters formed during an order-disorder transition and demonstrate the coexistence of the two phases in a region of 2-3 K around the transition temperature TN~215 K. Single crystals of NH4H2AsO4, a model hydrogen-bonded compound, show an antiferroelectric-paraelectric transition studied by means of highly sensitive magic angle spinning 15N NMR at 21.1 T. The phase co-existence is demonstrated by a double-peak structure of the chemical shift. Two-dimensional chemical exchange spectroscopy and spin-lattice relaxation time (T1) measurements show that the clusters are dynamic with sizes ~50 nm and lifetimes approaching seconds as T->TN. Their occupancy increases rapidly to fill the crystal volume below $T_N$. This study provides evidence for the commonality of the phase transitions in systems with electric properties and provides an improved spectroscopic method for such studies.

Background: Elevated sympathetic activity is associated with kidney dysfunction. Here we used twin pairs to probe heritability of GFR and its genetic covariance with other traits. Methods: We evaluated renal and adrenergic phenotypes in twins. GFR was estimated by CKD-EPI algorithm. Heritability and genetic covariance of eGFR and associated risk traits were estimated by variance- components. Meta-analysis probed reproducibility of DBH genetic effects. Effect of DBH genetic variation on renal disease was tested in the NIDDK-AASK cohort. Results: Norepinephrine secretion rose across eGFR tertiles while eGFR fell (p, 0.0001). eGFR was heritable, at h2= 67.364.7% (p = 3.0E-18), as were secretion of norepinephrine (h2= 66.565.0%, p = 3.2E-16) and dopamine (h2= 56.565.6%, p = 1.8E-13), and eGFR displayed genetic co-determination (covariance) with norepinephrine (rG=20.55760.088, p = 1.11E- 08) as well as dopamine (rG=20.22360.101, p = 2.3E-02). Since dopamine b-hydroxylase (DBH) catalyzes conversion of dopamine to norepinephrine, we studied functional variation at DBH ; DBH promoter haplotypes predicted transcriptional activity (p, 0.001), plasma DBH (p, 0.0001) and norepinephrine (p = 0.0297) secretion ; transcriptional activity was inversely (p, 0.0001) associated with basal eGFR. Meta- analysis validated DBH haplotype effects on eGFR across 3 samples. In NIDDK-AASK, we established a role for DBH promoter variation in long-term renal decline rate (GFR slope, p = 0.003). Conclusions: The heritable GFR trait shares genetic determination with catecholamines, suggesting new pathophysiologic, diagnostic and therapeutic approaches towards disorders of GFR as well as CKD. Adrenergic activity may play a role in progressive renal decline, and genetic variation at DBH may assist in profiling subjects for rational preventive treatment.

We report pulse-field magnetization, ac susceptibility, and 100 GHz electron spin resonance (ESR) measurements on the S = 5/2 two-dimensional triangular compound Ba3NbFe3Si2O14 with the N´eel temperature TN = 26 K . The magnetization curve shows an almost linear increase up to 60 T with no indication of a one-third magnetization plateau. An unusually large frequency dependence of the ac susceptibility in the temperature range of T = 20–100 K reveals a spin-glass behavior or superparamagnetism, signaling the presence of frustration-related slow magnetic fluctuations. The temperature dependence of the ESR linewidth exhibits two distinct critical regimes; (i) ΔHpp(T) α(T-TN)-p with the exponent p = 0.2(1)–0.2(3) for temperatures above 27 K, and (ii) ΔHpp(T) α(T- T)-p with T=12 K and p = 0.8.(1)–0.8(4) for temperatures between 12 and 27 K. This is interpreted as indicating a dimensional crossover of magnetic interactions and the persistence of short-range correlations with a helically ordered state.

We report ac susceptibility and high-frequency electron spin resonance (ESR) measurements on the geometrically frustrated compound Ba$_3$NbFe$_3$Si$_2$O$_{14}$ with the N\'{e}el temperature $T_N=27 K$. An unusually large frequency-dependence of ac susceptibility in the temperature range of 20 - 100 K reveals a spin-glass-like behavior, signalling the presence of frustration related slow magnetic fluctuations. ESR experiments show a multi-step magnetic and spin chirality ordering process. For temperatures above 30 K, the weak temperature dependence of the ESR linewidth $\Delta H_{pp}\propto T^{-p}$ with $p=0.8$ evidences the development of short-range correlated spin clusters. The critical broadening with $p =1.8$, persisting down to 14 K, indicates the coexistence of the short-range ordered spin clusters within a helically ordered state. Below 9.5 K, the anomalously large decrease of the linewidth reveals the stabilization of a long-range ordered state with one chirality., Comment: one-columb 10 pages, 3 figures

A new and powerful probe of the origin and evolution of structures in the Universe has emerged and been actively developed over the last decade. In the coming decade, non-Gaussianity, i.e., the study of non-Gaussian contributions to the correlations of cosmological fluctuations, will become an important probe of both the early and the late Universe. Specifically, it will play a leading role in furthering our understanding of two fundamental aspects of cosmology and astrophysics: (i) the physics of the very early universe that created the primordial seeds for large-scale structures, and (ii) the subsequent growth of structures via gravitational instability and gas physics at later times. To date, observations of fluctuations in the Cosmic Microwave Background (CMB) and the Large-Scale Structure of the Universe (LSS) have focused largely on the Gaussian contribution as measured by the two-point correlations (or the power spectrum) of density fluctuations. However, an even greater amount of information is contained in non-Gaussianity and a large discovery space therefore still remains to be explored. Many observational probes can be used to measure non-Gaussianity, including CMB, LSS, gravitational lensing, Lyman-alpha forest, 21-cm fluctuations, and the abundance of rare objects such as clusters of galaxies and high-redshift galaxies. Not only does the study of non-Gaussianity maximize the science return from a plethora of present and future cosmological experiments and observations, but it also carries great potential for important discoveries in the coming decade., Comment: 8 pages, 1 figure. Science White Paper submitted to the Cosmology and Fundamental Physics (CFP) Science Frontier Panel of the Astro 2010 Decadal Survey (v2,v3,v4) More co-signers and references added

The Cold Dark Matter theory of gravitationally-driven hierarchical structure formation has earned its status as a paradigm by explaining the distribution of matter over large spans of cosmic distance and time. However, its central tenet, that most of the matter in the universe is dark and exotic, is still unproven; the dark matter hypothesis is sufficiently audacious as to continue to warrant a diverse battery of tests. While local searches for dark matter particles or their annihilation signals could prove the existence of the substance itself, studies of cosmological dark matter in situ are vital to fully understand its role in structure formation and evolution. We argue that gravitational lensing provides the cleanest and farthest-reaching probe of dark matter in the universe, which can be combined with other observational techniques to answer the most challenging and exciting questions that will drive the subject in the next decade: What is the distribution of mass on sub-galactic scales? How do galaxy disks form and bulges grow in dark matter halos? How accurate are CDM predictions of halo structure? Can we distinguish between a need for a new substance (dark matter) and a need for new physics (departures from General Relativity)? What is the dark matter made of anyway? We propose that the central tool in this program should be a wide-field optical imaging survey, whose true value is realized with support in the form of high-resolution, cadenced optical/infra-red imaging, and massive-throughput optical spectroscopy., White paper submitted to the 2010 Astronomy & Astrophysics Decadal Survey

We report on the use of $^{69,71}$Ga nuclear magnetic resonance to probe spin dynamics in the rare-earth kagom\'{e} system Pr$_3$Ga$_5$SiO$_{14}$. We find that the spin-lattice relaxation rate $^{69}1/T_1$ exhibits a maximum around 30 K, below which the Pr$^{3+}$ spin correlation time $\tau$ shows novel field-dependent behavior consistent with a field-dependent gap in the excitation spectrum. The spin-spin relaxation rate $^{69}1/T_{2}$ exhibits a peak at a lower temperature (10 K) below which field-dependent power-law behavior close to $T^{2}$ is observed. These results point to field-induced formation of nanoscale magnetic clusters consistent with recent neutron scattering measurements.

Cr^5+ doped K_3NbO_8, considered to be useful as a electron spin qubit, has been investigated by pulsed X-band (~9.7 GHz) and 240 GHz electron paramagnetic resonance and electron nuclear double resonance (ENDOR). Comparison of the low temperature electronic spin-lattice relaxation rate 1/T_1 at 9.7 and 240 GHz shows that it is 250 times faster at 240 GHz than at X-band. On the other hand, the spin-spin relaxation rate 1/T_2 appears largely frequency independent and is very likely related to the superhyperfine (SHF) coupling of the Cr^5+ electron with the surrounding potassium and niobium nuclei. This coupling was investigated by HYSCORE at 9.7 GHz and pulsed Mims ENDOR at 240 GHz. The high frequency and field enabled us to unambiguously measure the hyperfine and quadrupole couplings of the 39K in spite of its small magnetic moment. We find that the largest 39K SHF coupling is positive, with 0.522 MHz and 0.20 MHz as its isotropic and dipolar parts respectively. 93Nb ENDOR was dominantly due to its quadrapolar interaction, with a coupling of about 0.8 MHz, and a SHF coupling of about 0.08 MHz. The significance of these data to spin qubit studies is pointed out.

We report on the use of $^{69,71}$Ga nuclear magnetic resonance to probe spin dynamics in the rare-earth kagom�� system Pr$_3$Ga$_5$SiO$_{14}$. We find that the spin-lattice relaxation rate $^{69}1/T_1$ exhibits a maximum around 30 K, below which the Pr$^{3+}$ spin correlation time $��$ shows novel field-dependent behavior consistent with a field-dependent gap in the excitation spectrum. The spin-spin relaxation rate $^{69}1/T_{2}$ exhibits a peak at a lower temperature (10 K) below which field-dependent power-law behavior close to $T^{2}$ is observed. These results point to field-induced formation of nanoscale magnetic clusters consistent with recent neutron scattering measurements.

We report coherent spin manipulation on Cr$^{5+}$ (\emph{S} = 1/2, \emph{I} = 0) doped K$_3$NbO$_8$, which constitutes a dilute two-level model relevant for use as a spin qubit. Rabi oscillations are observed for the first time in a spin system based on transition metal oxides up to room temperature. At liquid helium temperature the phase coherence relaxation time \emph{$T_2$} reaches $\sim 10$ $\mu$s and, with a Rabi frequency of 20 MHz, yields a single qubit figure of merit \emph{$Q_M$} of about 500. This shows that a diluted ensemble of Cr$^{5+}$ (\emph{S} = 1/2) doped K$_3$NbO$_8$ is a potential candidate for solid-state quantum information processing., Comment: 4 pages

We present an inelastic neutron scattering (INS) study of the excitation spectrum of a model S = 1/2 equilateral Heisenberg trimer, Cu_3(O_2C_16H_23)_6.1.2C_6H_12. Earlier measurements were interpreted on the basis of a spin ground state consisting of a pair of degenerate S = 1/2 doublets, with an S = 3/2 quartet excited state. Given that the simplest model of magnetism for this compound includes a degenerate ground state, using thermodynamic probes to determine the excitation energy between the ground and excited states is challenging. An estimate of the excitation energy between the ground and excited states based on magnetic susceptibility measurements is roughly ~28 meV. INS measurements of this compound are likewise challenging since inter- and intramolecular vibrational modes associated with the organic ligands are at frequencies similar to the magnetic excitations. However, by measuring a non-magnetic analog, i.e. ligands only, as well as the temperature dependence of the excitations in the magnetic system, we are able to determine the excitation energy as being approximately 36.5 meV at T = 10 K, with a gradual softening to 32 meV with increasing temperature. We emphasize the consideration of ligand/lattice based excitations while interpreting magnetic excitations of such nanomagnetic systems containing organic molecules while underscoring the importance of INS in determining the magnetic excitation spectrum in systems with degenerate ground states., Comment: Submitted to Phys. Rev. B. Resubmitted to cond-mat with further analysis

The symmetry of magnetic quantum tunneling (MQT) in the single molecule magnet Mn12-acetate has been determined by sensitive low-temperature magnetic measurements in the pure quantum tunneling regime and high frequency EPR spectroscopy in the presence of large transverse magnetic fields. The combined data set definitely establishes the transverse anisotropy terms responsible for the low temperature quantum dynamics. MQT is due to a disorder induced locally varying quadratic transverse anisotropy associated with rhombic distortions in the molecular environment (2nd order in the spin-operators). This is superimposed on a 4th order transverse magnetic anisotropy consistent with the global (average) S4 molecule site symmetry. The hard axes associated with these forms of the transverse anisotropy are not collinear, leading to a complex interplay between local and global symmetries, the consequences of which are analyzed in detail., 26 two-column pages, 34 figures - content changed Accepted in Journal of Low Temperature Physics

The variation with microwave frequency and temperature of previously reported anomalous peaks in the EPR spectra of Mn12-acetate, under large transverse fields, reveals that the molecular easy magnetization axes are tilted with respect to the global symmetry direction. More importantly, on the basis of the angle-dependence of fine structures observed in the EPR spectra we infer that the tilt distribution must be discrete, as was previously suspected from studies which demonstrated the presence of a locally varying rhombic anisotropy [S. Hill et al., Phys. Rev. Lett. 90, 217204 (2003)]. The tilts are confined to two orthogonal planes, and the distribution extends up to ~1.7 degrees away from the the global easy (z-) axis. We ascribe the tilting to the hydrogen-bonding effect associated with the disordered acetic acid solvent molecules. The effect is considerably larger than deduced from x-ray diffraction analyses. These data constitute the sought-after evidence for the presence of transverse fields in Mn12-acetate, and provide a possible explanation for the lack of selection rules in the resonant quantum tunneling behavior seen in low-temperature hysteresis experiments for this S = 10 system., Comment: 39 pages, including 13 low-resolution figures, Phys. Rev. B (Sept. 1, 2004)

We present detailed angle-dependent single crystal electron paramagnetic resonance (EPR) data for field rotations in the hard plane of the S=10 single molecule magnet Mn12-acetate. A clear four-fold variation in the resonance positions may be attributed to an intrinsic fourth order transverse anisotropy (O44). Meanwhile, a four-fold variation of the EPR lineshapes confirms a recently proposed model wherein disorder associated with the acetic acid of crystallization induces a locally varying quadratic (rhombic) transverse anisotropy (O22). These findings explain most aspects of the magnetic quantum tunneling observed in Mn12-acetate., 7 pages, including figures, accepted for publication in Phys. Rev. Lett

We examine theoretically electron paramagnetic resonance (EPR) lineshapes as functions of resonance frequency, energy level, and temperature for single crystals of three different kinds of single-molecule nanomagnets (SMMs): Mn$_{12}$ acetate, Fe$_8$Br, and the $S=9/2$ Mn$_4$ compound. We use a density-matrix equation and consider distributions in the uniaxial (second-order) anisotropy parameter $D$ and the $g$ factor, caused by possible defects in the samples. Additionally, weak intermolecular exchange and electronic dipole interactions are included in a mean-field approximation. Our calculated linewidths are in good agreement with experiments. We find that the distribution in $D$ is common to the three examined single-molecule magnets. This could provide a basis for a proposed tunneling mechanism due to lattice defects or imperfections. We also find that weak intermolecular exchange and dipolar interactions are mainly responsible for the temperature dependence of the lineshapes for all three SMMs, and that the intermolecular exchange interaction is more significant for Mn$_4$ than for the other two SMMs. This finding is consistent with earlier experiments and suggests the role of spin-spin relaxation processes in the mechanism of magnetization tunneling., To appear in the proceedings of 2002 MRS fall meeting

We present a detailed investigation of the temperature and frequency dependence of the anomalous EPR transitions first observed in Mn12-acetate by Hill et al. [Phys. Rev. Lett. 80, 2453 (1998)]. The most dominant of these transitions manifest themselves as an extra series of EPR absorption peaks for spectra obtained with the DC field applied within the hard magnetic plane of a single crystal sample. Recent studies by Amigo et al. [Phys. Rev. B 65, 172403 (2002)] have attributed these extra peaks to a strain induced transverse quadratic anisotropy which gives rise to distinct Mn12-acetate species, each having a distinct EPR spectrum; on the basis of these measurements, it has been suggested that this transverse anisotropy is responsible for the tunneling in Mn12-acetate. Our temperature and frequency dependent measurements demonstrate unambiguously that these anomalous EPR absorptions vanish as the temperature tends to zero, thereby indicating that they correspond to transitions from an excited state of the molecule. We argue that this low lying excited state corresponds to an S = 9 multiplet having very similar zero-field crystal parameters to the S = 10 state, and lying only about 10-15 k_B above the S = 10 (M_S = +/-9) ground state. These findings also compare favorably with available neutron scattering data., Comment: 11 pages, including figures

Resistivity measurements are reported for single crystals of Mn$_{12}$-Acetate and Fe$_8$Br$_8$. Both materials exhibit a semiconductor-like, thermally activated behavior over the 200-300 K range. The activation energy, $E_a$, obtained for Mn$_{12}$-Acetate was 0.37 $\pm$ 0.05 eV, which is to be contrasted with the value of 0.55 eV deduced from the earlier reported absorption edge measurements and the range of 0.3-1 eV from intramolecular density of states calculations, assuming $2E_a$= $E_g$, the optical band gap. For Fe$_8$Br$_8$, $E_a$ was measured as 0.73 $\pm$ 0.1 eV, and is discussed in light of the available approximate band structure calculations. Some plausible pathways are indicated based on the crystal structures of both lattices. For Mn$_{12}$-Acetate, we also measured photoconductivity in the visible range; the conductivity increased by a factor of about eight on increasing the photon energy from 632.8 nm (red) to 488 nm (blue). X-ray irradiation increased the resistivity, but $E_a$ was insensitive to exposure., Comment: 7 pages, 8 figures

High Frequency electron paramagnetic resonance has been used to observe the magnetic dipole, $\Delta$ M$_s$ = $\pm$ 1, transitions in the $S = 9$ excited state of the single molecule magnet Fe$_8$Br$_8$. A Boltzmann analysis of the measured intensities locates it at 24 $\pm$ 2 K above the $S = 10$ ground state, while the line positions yield its magnetic parameters D = -0.27 K, E = $\pm$0.05 K, and B$_4^0$ = -1.3$\times$ 10$^{-6}$ K. D is thus smaller by 8% and E larger by 7% than for $S = 10$. The anisotropy barrier for $S = 9$ is estimated as 22 K,which is 25% smaller than that for $S = 10$ (29 K). These data also help assign the spin exchange constants(J's) and thus provide a basis for improved electronic structure calculations of Fe$_8$Br$_8$., Comment: 7 pages, Figs included in text, submitted to PRB

We examine quantitatively the temperature dependence of the linewidths and line shifts in electron paramagnetic resonance experiments on single crystals of the single-molecule magnets Fe$_8$ and Mn$_{12}$, at fixed frequency, with an applied magnetic field along the easy axis. We include inter-molecular spin-spin interactions (dipolar and exchange) and distributions in both the uniaxial anisotropy parameter $D$ and the Land\'{e} $g$-factor. The temperature dependence of the linewidths and the line shifts are mainly caused by the spin-spin interactions. For Fe$_8$ and Mn$_{12}$, the temperature dependence of the calculated line shifts and linewidths agrees well with the trends of the experimental data. The linewidths for Fe$_8$ reveal a stronger temperature dependence than those for Mn$_{12}$, because for Mn$_{12}$ a much wider distribution in $D$ overshadows the temperature dependence of the spin-spin interactions. For Fe$_8$, the line-shift analysis suggests two competing interactions: a weak ferromagnetic exchange coupling between neighboring molecules and a longer-ranged dipolar interaction. This result could have implications for ordering in Fe$_8$ at low temperatures., Comment: published version

We devise a method to measure the abundance of satellite halos in gravitational lens galaxies, and apply our method to a sample of 7 lens systems. After using Monte Carlo simulations to verify the method, we find that substructure comprises fraction f=0.02 (median, 0.006, Comment: ApJ in press, 23 pages, 6 figures

The properties of multiple image gravitational lenses require a fractional surface mass density in satellites of f=0.02 (0.006 < f < 0.07 at 90% confidence) that is consistent with the expectations for CDM. The characteristic satellite mass scale, 10^6-10^9 Msun, is also consistent with the expectations for CDM. The agreement between the observed and expected density of CDM substructure shows that most low mass galactic satellites fail to form stars, and this absence of star formation explains the discrepancy between the number of observed Galactic satellites and CDM predictions rather than any modification to the CDM theory such as self-interacting dark matter or a warm dark matter component., to appear in the ESO Workshop on The Mass of Galaxies at Low and High Redshift, 6 pages, 5 figures

High-Sensitivity Electron Paramagnetic Resonance experiments have been carried out in fresh and stressed Mn12-Acetate single crystals for frequencies ranging from 40 GHz up to 110 GHz. The high number of crystal dislocations formed in the stressing process introduces a E(S_x^2-S_y^2) transverse anisotropy term in the spin hamiltonian. From the behaviour of the resonant absorptions on the applied transverse magnetic field we have obtained an average value for E = 22 mK, corresponding to a concentration of dislocations per unit cell of c = 10^-3., 13 pages and 4 figures