348 research outputs found

    Geodatabase Development to Support Hyperspectral Imagery Exploitation

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    Geodatabase development for coastal studies conducted by the Naval Research Laboratory (NRL) is essential to support the exploitation of hyperspectral imagery (HSI). NRL has found that the remote sensing and mapping science community benefits from coastal classifications that group coastal types based on similar features. Selected features in project geodatabases relate to significant biological and physical forces that shape the coast. The project geodatabases help researchers understand factors that are necessary for imagery post processing, especially those features having a high degree of temporal and spatial variability. NRL project geodatabases include a hierarchy of environmental factors that extend from shallow water bottom types and beach composition to inland soil and vegetation characteristics. These geodatabases developed by NRL allow researchers to compare features among coast types. The project geodatabases may also be used to enhance littoral data archives that are sparse. This paper highlights geodatabase development for recent remote sensing experiments in barrier island, coral, and mangrove coast types

    Orbital dependent nucleonic pairing in the lightest known isotopes of tin

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    By studying the 109Xe-->105Te-->101Sn superallowed alpha-decay chain, we observe low-lying states in 101Sn, the one-neutron system outside doubly magic 100Sn. We find that the spins of the ground state (J = 7=2) and first excited state (J = 5=2) in 101Sn are reversed with respect to the traditional level ordering postulated for 103Sn and the heavier tin isotopes. Through simple arguments and state-of-the-art shell model calculations we explain this unexpected switch in terms of a transition from the single-particle regime to the collective mode in which orbital-dependent pairing correlations, dominate.Comment: 5 pages 3 figure

    Quantum key distribution with 1.25 Gbps clock synchronization

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    We have demonstrated the exchange of sifted quantum cryptographic key over a 730 meter free-space link at rates of up to 1.0 Mbps, two orders of magnitude faster than previously reported results. A classical channel at 1550 nm operates in parallel with a quantum channel at 845 nm. Clock recovery techniques on the classical channel at 1.25 Gbps enable quantum transmission at up to the clock rate. System performance is currently limited by the timing resolution of our silicon avalanche photodiode detectors. With improved detector resolution, our technique will yield another order of magnitude increase in performance, with existing technology.Comment: 6 pages, 3 figures, 99 kB .pdf documen

    Solitary waves in the Nonlinear Dirac Equation

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    In the present work, we consider the existence, stability, and dynamics of solitary waves in the nonlinear Dirac equation. We start by introducing the Soler model of self-interacting spinors, and discuss its localized waveforms in one, two, and three spatial dimensions and the equations they satisfy. We present the associated explicit solutions in one dimension and numerically obtain their analogues in higher dimensions. The stability is subsequently discussed from a theoretical perspective and then complemented with numerical computations. Finally, the dynamics of the solutions is explored and compared to its non-relativistic analogue, which is the nonlinear Schr{\"o}dinger equation. A few special topics are also explored, including the discrete variant of the nonlinear Dirac equation and its solitary wave properties, as well as the PT-symmetric variant of the model

    Relative validity of the Planetary Health Diet Index by comparison with usual nutrient intakes, plasma food consumption biomarkers, and adherence to the Mediterranean diet among European adolescents: the HELENA study

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    Purpose The EAT-Lancet Commission proposed an evidence-based global reference diet to improve human health within planetary boundaries. Recently, the Planetary Health Diet Index (PHDI) was developed based on the EAT-Lancet recommendations and validated among Brazilian adults. However, the relative validity of the PHDI in adolescents has yet to be assessed. Thus, we aimed to evaluate the relative validity of the PHDI in European adolescents. Methods We used cross-sectional data from 1804 adolescents (12.5–17.5 years) enrolled in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study. The PHDI (0–150 points) was calculated based on dietary intake data from two non-consecutive 24-h dietary recalls. Associations between the PHDI and usual nutrient intakes, plasma food consumption biomarkers, and adherence to the Mediterranean diet were evaluated using multivariable-adjusted mixed-effects linear regression models. Results Higher PHDI score was associated with greater intakes of nutrients predominantly from plant-source foods, such as vegetable protein, vitamin E, and folate and with lower intake of nutrients predominately from animal-source foods, such as total and saturated fat, cholesterol, and animal protein. Furthermore, a higher PHDI score was also positively associated with plasma β-carotene, vitamin C, vitamin D, folate, and ferritin concentrations, while negatively associated with trans-fatty acids concentration. Moreover, higher PHDI was related to a greater adherence to the Mediterranean dietary pattern. Conclusions The PHDI showed good relative validity among adolescents in the HELENA study. Hence, future research should assess adherence to the PHDI and long-term health outcomes

    Beta-strength and anti-neutrino spectra from total absorption spectroscopy of a decay chain \u3csup\u3e142\u3c/sup\u3eCs→\u3csup\u3e142\u3c/sup\u3e Ba →\u3csup\u3e142\u3c/sup\u3eLa

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    Beta decays of mass A = 142 isobaric chain starting from 142Cs have been investigated by means of Modular Total Absorption Spectrometer (MTAS) and on-line mass separation at Oak Ridge National Laboratory. The beta strength distribution derived for 142Cs decay from MTAS spectra is showing significant differences in β-feeding pattern when compared to the values listed at nuclear databases. MTAS results are shifting the associated anti-neutrino energy spectrum towards lower energies. A decay pattern deduced for 142Ba is similar to earlier reported results

    Single-molecule experiments in biological physics: methods and applications

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    I review single-molecule experiments (SME) in biological physics. Recent technological developments have provided the tools to design and build scientific instruments of high enough sensitivity and precision to manipulate and visualize individual molecules and measure microscopic forces. Using SME it is possible to: manipulate molecules one at a time and measure distributions describing molecular properties; characterize the kinetics of biomolecular reactions and; detect molecular intermediates. SME provide the additional information about thermodynamics and kinetics of biomolecular processes. This complements information obtained in traditional bulk assays. In SME it is also possible to measure small energies and detect large Brownian deviations in biomolecular reactions, thereby offering new methods and systems to scrutinize the basic foundations of statistical mechanics. This review is written at a very introductory level emphasizing the importance of SME to scientists interested in knowing the common playground of ideas and the interdisciplinary topics accessible by these techniques. The review discusses SME from an experimental perspective, first exposing the most common experimental methodologies and later presenting various molecular systems where such techniques have been applied. I briefly discuss experimental techniques such as atomic-force microscopy (AFM), laser optical tweezers (LOT), magnetic tweezers (MT), biomembrane force probe (BFP) and single-molecule fluorescence (SMF). I then present several applications of SME to the study of nucleic acids (DNA, RNA and DNA condensation), proteins (protein-protein interactions, protein folding and molecular motors). Finally, I discuss applications of SME to the study of the nonequilibrium thermodynamics of small systems and the experimental verification of fluctuation theorems. I conclude with a discussion of open questions and future perspectives.Comment: Latex, 60 pages, 12 figures, Topical Review for J. Phys. C (Cond. Matt

    Genetic analysis of male reproductive success in relation to density in the zebrafish, Danio rerio

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    BACKGROUND: We used behavioural and genetic data to investigate the effects of density on male reproductive success in the zebrafish, Danio rerio. Based on previous measurements of aggression and courtship behaviour by territorial males, we predicted that they would sire more offspring than non-territorial males. RESULTS: Microsatellite analysis of paternity showed that at low densities territorial males had higher reproductive success than non-territorial males. However, at high density territorial males were no more successful than non-territorials and the sex difference in the opportunity for sexual selection, based on the parameter I(mates), was low. CONCLUSION: Male zebrafish exhibit two distinct mating tactics; territoriality and active pursuit of females. Male reproductive success is density dependent and the opportunity for sexual selection appears to be weak in this species
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