4,129 research outputs found

    Spin Asymmetry and Gerasimov-Drell-Hearn Sum Rule for the Deuteron

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    An explicit evaluation of the spin asymmetry of the deuteron and the associated GDH sum rule is presented which includes photodisintegration, single and double pion and eta production as well. Photodisintegration is treated with a realistic retarded potential and a corresponding meson exchange current. For single pion and eta production the elementary operator from MAID is employed whereas for double pion production an effective Lagrangean approach is used. A large cancellation between the disintegration and the meson production channels yields for the explicit GDH integral a value of 27.31 μ\mub to be compared to the sum rule value 0.65 μ\mub.Comment: 4 pages, 5 figures, revtex

    The Whooping Crane in Mexico: Past, Present, and Future?

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    We reviewed ornithological, historic, anthropological, and archaeological records for evidence of whooping cranes (Grus americana) in Mexico. Records of whooping cranes in Mexico span 88 years (1863-1951) and cluster in 3 areas. Wintering records come from the northern highlands (Durango, and possibly Chihuahua), the central highlands (Guanajuato, Jalisco), and northeastern Tamaulipas, where the bird was also found in summer and might have bred. Later records (1970’s and 1980’s) of whooping cranes in the northern highlands are from individual birds released into the experimental migratory population that formerly migrated from Idaho to New Mexico, USA. Many of the wetlands used by whooping cranes remain and, though faced with a variety of threats, are conservation priority areas and some are already protected. We suggest 3 scenarios by which whooping cranes might return to winter in Mexico. The first 2 involve dispersal by birds wintering at the Aransas National Wildlife Refuge, Texas, USA, by either population growth or ecosystem changes or degradation (e.g., climate change, reduced freshwater inflows) at the refuge. Finally, reintroduction of a migratory population might target part of Mexico as a wintering area. We encourage investigation of wetlands in Mexico, especially in northeastern Tamaulipas for their potential as future wintering areas. Our preliminary survey of historic Spanish language publications covering the 1500’s to early 1600’s found clear references to cranes in which, for example, cranes are described feeding with geese in grain fields. Cranes are mentioned in accounts of the DeSoto and Coronado expeditions as well as the travels of Bishop Alonso de la Mota y Escobar. Unfortunately, these accounts do not adequately describe the birds for species identification. Only, the Florentine Codex by Fray Bernardino de Sahagun provides a description of the sandhill crane (G. canadensis) from near Mexico City at the time of Spanish conquest of the Aztecs. Continued searches of early Spanish language publications might yield more information of the historic distribution of cranes in Mexico

    Gravity or turbulence? -III. Evidence of pure thermal Jeans fragmentation at ~0.1 pc scale

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    We combine previously published interferometric and single-dish data of relatively nearby massive dense cores that are actively forming stars to test whether their `fragmentation level' is controlled by turbulent or thermal support. We find no clear correlation between the fragmentation level and velocity dispersion, nor between the observed number of fragments and the number of fragments expected when the gravitationally unstable mass is calculated including various prescriptions for `turbulent support'. On the other hand, the best correlation is found for the case of pure thermal Jeans fragmentation, for which we infer a core formation efficiency around 13 per cent, consistent with previous works. We conclude that the dominant factor determining the fragmentation level of star-forming massive dense cores at 0.1 pc scale seems to be thermal Jeans fragmentation.Comment: accepted in MNRA

    Priorities for synthesis research in ecology and environmental science

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    Synthesis research in ecology and environmental science improves understanding, advances theory, identifies research priorities, and supports management strategies by linking data, ideas, and tools. Accelerating environmental challenges increases the need to focus synthesis science on the most pressing questions. To leverage input from the broader research community, we convened a virtual workshop with participants from many countries and disciplines to examine how and where synthesis can address key questions and themes in ecology and environmental science in the coming decade. Seven priority research topics emerged: (1) diversity, equity, inclusion, and justice (DEIJ), (2) human and natural systems, (3) actionable and use-inspired science, (4) scale, (5) generality, (6) complexity and resilience, and (7) predictability. Additionally, two issues regarding the general practice of synthesis emerged: the need for increased participant diversity and inclusive research practices; and increased and improved data flow, access, and skill-building. These topics and practices provide a strategic vision for future synthesis in ecology and environmental science

    A global transcriptional network connecting noncoding mutations to changes in tumor gene expression.

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    Although cancer genomes are replete with noncoding mutations, the effects of these mutations remain poorly characterized. Here we perform an integrative analysis of 930 tumor whole genomes and matched transcriptomes, identifying a network of 193 noncoding loci in which mutations disrupt target gene expression. These 'somatic eQTLs' (expression quantitative trait loci) are frequently mutated in specific cancer tissues, and the majority can be validated in an independent cohort of 3,382 tumors. Among these, we find that the effects of noncoding mutations on DAAM1, MTG2 and HYI transcription are recapitulated in multiple cancer cell lines and that increasing DAAM1 expression leads to invasive cell migration. Collectively, the noncoding loci converge on a set of core pathways, permitting a classification of tumors into pathway-based subtypes. The somatic eQTL network is disrupted in 88% of tumors, suggesting widespread impact of noncoding mutations in cancer

    Classification of burn injuries using near-infrared spectroscopy.

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    Early surgical management of those burn injuries that will not heal spontaneously is critical. The decision to excise and graft is based on a visual assessment that is often inaccurate but yet continues to be the primary means of grading the injury. Superficial and intermediate partial-thickness injuries generally heal with appropriate wound care while deep partial- and full-thickness injuries generally require surgery. This study explores the possibility of using near-infrared spectroscopy to provide an objective and accurate means of distinguishing shallow injuries from deeper burns that require surgery. Twenty burn injuries are studied in five animals, with burns covering <1% of the total body surface area. Carefully controlled superficial, intermediate, and deep partial-thickness injuries as well as full-thickness injuries could be studied with this model. Near-infrared reflectance spectroscopy was used to evaluate these injuries 1 to 3 hours after the insult. A probabilistic model employing partial least-squares logistic regression was used to determine the degree of injury, shallow (superficial or intermediate partial) from deep (deep partial and full thickness), based on the reflectance spectrum of the wound. A leave-animal-out cross-validation strategy was used to test the predictive ability of a 2-latent variable, partial least-squares logistic regression model to distinguish deep burn injuries from shallow injuries. The model displayed reasonable ranking quality as summarized by the area under the receiver operator characteristics curve, AUC = 0.879. Fixing the threshold for the class boundaries at 0.5 probability, the model sensitivity (true positive fraction) to separate deep from shallow burns was 0.90, while model specificity (true negative fraction) was 0.83. Using an acute porcine model of thermal burn injuries, the potential of near-infrared spectroscopy to distinguish between shallow healing burns and deeper burn injuries was demonstrated. While these results should be considered as preliminary and require clinical validation, a probabilistic model capable of differentiating these classes of burns would be a significant aid to the burn specialist

    Efficacy of a 6-week Novel Exergaming Intervention Guided by Heart Rate Zones on Aerobic Performance in Children with Fetal Alcohol Spectrum Disorder and Attention-deficit/Hyperactivity Disorder: A Feasibility Study

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    International Journal of Exercise Science 16(3): 710-720, 2023. The purpose of this study was to determine the feasibility of a novel exergaming intervention guided by heart rate zones for children and adolescents with fetal alcohol spectrum disorder (FASD) and attention-deficit/hyperactivity disorder (ADHD). Eight study participants (6 females, 2 males, mean age= 11.4±1.4 years old) participated twice weekly over six weeks to complete twelve multimodal exergaming sessions. Participants significantly improved 6MWT from baseline to week 6 (575.4±55.0 m to 732.8±58.9 m; P\u3c0.01), which conferred a 31% improvement in estimated VO2max (31.5±5.5 ml/kg/min to 40.9±5.9 ml/kg/min), respectively. There was an upward trend of the mean percentage of time spent in the intermediate HR zones over the course of the 6-week intervention. These findings may provide value to the field as they support the clinical utility and promising effects of cardiovascular improvement in children who engage in a compelling exergaming intervention. In doing so, this establishes a preliminary understanding of how to augment routine physical exercise through exergaming using visually targeted heart rate zones

    Multicomponent Analysis of Junctional Movements Regulated by Myosin II Isoforms at the Epithelial Zonula Adherens

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    The zonula adherens (ZA) of epithelial cells is a site of cell-cell adhesion where cellular forces are exerted and resisted. Increasing evidence indicates that E-cadherin adhesion molecules at the ZA serve to sense force applied on the junctions and coordinate cytoskeletal responses to those forces. Efforts to understand the role that cadherins play in mechanotransduction have been limited by the lack of assays to measure the impact of forces on the ZA. In this study we used 4D imaging of GFP-tagged E-cadherin to analyse the movement of the ZA. Junctions in confluent epithelial monolayers displayed prominent movements oriented orthogonal (perpendicular) to the ZA itself. Two components were identified in these movements: a relatively slow unidirectional (translational) component that could be readily fitted by least-squares regression analysis, upon which were superimposed more rapid oscillatory movements. Myosin IIB was a dominant factor responsible for driving the unilateral translational movements. In contrast, frequency spectrum analysis revealed that depletion of Myosin IIA increased the power of the oscillatory movements. This implies that Myosin IIA may serve to dampen oscillatory movements of the ZA. This extends our recent analysis of Myosin II at the ZA to demonstrate that Myosin IIA and Myosin IIB make distinct contributions to junctional movement at the ZA

    Searches for Lepton Flavour Violation at a Linear Collider

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    We investigate the prospects for detection of lepton flavour violation in sparticle production and decays at a Linear Collider (LC), in models guided by neutrino oscillation data. We consider both slepton pair production and sleptons arising from the cascade decays of non-leptonic sparticles. We study the expected signals when lepton-flavour-violating (LFV) interactions are induced by renormalization effects in the Constrained Minimal Supersymmetric extension of the Standard Model (CMSSM), focusing on the subset of the supersymmetric parameter space that also leads to cosmologically interesting values of the relic neutralino LSP density. Emphasis is given to the complementarity between the LC, which is sensitive to mixing in both the left and right slepton sectors, and the LHC, which is sensitive primarily to mixing in the right sector. We also emphasize the complementarity between searches for rare LFV processes at the LC and in low-energy experiments.Comment: 19 pages, 10 figure

    Shaping the spectral correlation of bi-photon quantum frequency combs by multi-frequency excitation of an SOI integrated nonlinear resonator

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    : We reveal the generation of a broadband (&gt; 1.9 THz) bi-photon quantum frequency comb (QFC) in a silicon-on-insulator (SOI) Fabry-Pérot micro-cavity and the control of its spectral correlation properties. Correlated photon pairs are generated through three spontaneous four-wave mixing (SFWM) processes by using a co-polarized bi-chromatic coherent input with power P1 and P2 on adjacent resonances of the nonlinear cavity. Adjusting the spectral power ratio r = P1/(P1 + P2) allows control over the influence of each process leading to an enhancement of the overall photon pair generation rate (PGR) μ(r) by a maximal factor of μ(r = 0.5)/μ(r = 0) ≈ 1.5, compared to the overall PGR provided by a single-pump configuration with the same power budget. We demonstrate that the efficiency aND of the non-degenerate excitation SFWM process (NDP) doubles the efficiency a1 ≈ a2 of the degenerate excitation SFWM processes (DP), showing a good agreement with the provided model
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