14,573 research outputs found

    \u3ci\u3eAcrobasis\u3c/i\u3e Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation

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    Acrobasis shoot moth infestations were evaluated in a young black walnut progeny test for 4 years, from ages 3 to 6. Infestation levels were greatest on the largest trees in the fourth and fifth year after plantation establishment, and were declining by the sixth year. Acrobasis infestation appears to be a problem primarily on young trees less than 2.5 m in height. There was no evidence for genetic resistance to Acrobasis infestation in black walnut

    Peology and Geochemistry of New Paired Martian Meteorites 12095 and LAR 12240

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    The meteorites LAR 12095 and LAR 12240 are believed to be paired Martian meteorites and were discovered during the Antarctic Search for Meteorites (ANSMET) 2012-2013 Season at Larkman Nunatak. The purpose of this study is to characterize these olivine-phyric shergottites by analyzing all mineral phases for major, minor and trace elements and examining their textural relationships. The goal is to constrain their crystallization history and place these shergottites among other Martian meteorites in order to better understand Martian geological history

    Dark matter annihilation and decay in dwarf spheroidal galaxies: The classical and ultrafaint dSphs

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    Dwarf spheroidal (dSph) galaxies are prime targets for present and future gamma-ray telescopes hunting for indirect signals of particle dark matter. The interpretation of the data requires careful assessment of their dark matter content in order to derive robust constraints on candidate relic particles. Here, we use an optimised spherical Jeans analysis to reconstruct the `astrophysical factor' for both annihilating and decaying dark matter in 21 known dSphs. Improvements with respect to previous works are: (i) the use of more flexible luminosity and anisotropy profiles to minimise biases, (ii) the use of weak priors tailored on extensive sets of contamination-free mock data to improve the confidence intervals, (iii) systematic cross-checks of binned and unbinned analyses on mock and real data, and (iv) the use of mock data including stellar contamination to test the impact on reconstructed signals. Our analysis provides updated values for the dark matter content of 8 `classical' and 13 `ultrafaint' dSphs, with the quoted uncertainties directly linked to the sample size; the more flexible parametrisation we use results in changes compared to previous calculations. This translates into our ranking of potentially-brightest and most robust targets---viz., Ursa Minor, Draco, Sculptor---, and of the more promising, but uncertain targets---viz., Ursa Major 2, Coma---for annihilating dark matter. Our analysis of Segue 1 is extremely sensitive to whether we include or exclude a few marginal member stars, making this target one of the most uncertain. Our analysis illustrates challenges that will need to be addressed when inferring the dark matter content of new `ultrafaint' satellites that are beginning to be discovered in southern sky surveys.Comment: 19 pages, 14 figures, submitted to MNRAS. Supplementary material available on reques

    Accuracy of Wrist-worn Physical Activity Monitors to Measure Energy Expenditure

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    IIn recent years, the popularity and demand of physical activity monitors has drastically risen with the need and want to improve physical fitness. Newer devices worn on the wrist measure both heart rate and energy expenditure but the accuracy of these measurements is unclear. PURPOSE: To measure the accuracy of three separate wrist-worn activity monitors to estimate energy expenditure during structured periods of aerobic exercise. METHODS: Twelve men and three women (22 ± 3 years, 25 ± 3 kg/m2) consented to participate in this study. Three different physical activity monitors, TomTom Cardio (TT), Microsoft Band (MB), and Fitbit Surge (FB), were randomly assigned to either the left or right wrist of each participant. The instructions for the testing procedure were thoroughly explained to every participant at the start of each trial. The treadmill started at a speed of 2 mph and increased by 1 mph every three minutes up to a max speed of 6 mph. Energy expenditure was estimated through direct measurement of oxygen consumed and carbon dioxide produced through a metabolic cart (MC, Parvo Medics True One ®2400). The mean bias in energy expenditure between MC and each device was calculated. Pearson product-moment correlations and 95% equivalence testing were also calculated. Statistical significance was set at an alpha level of 0.05. RESULTS: The mean bias between the MC and devices at 2 mph varied from -1.9 ± 1.1 kcal/min (FB) to 0.7 ± 1.0 kcal/min (MB) while the mean bias at 6 mph varied from -1.7 ± 2.1 kcal/min (MB) to 5.2 ± 1.7 kcal/min (TT). For total energy expenditure, all devices were significantly correlated with the MC (FB: r=0.66, p=0.007; TomTom: r=0.77, p\u3c0.001; MB: r=0.59, p=0.02). The mean bias for total energy expenditure was -25 ± 16 kcal for the FB, 26 ± 13 kcal for the TT, and -11 ± 17 kcal for the MB. The equivalence zone for MC was 88 kcal to 108 kcal but 90% confidence intervals of devices did not fall within this zone. CONCLUSION: The wrist-worn physical activity monitors used in this study that measure heart rate and energy expenditure tend to either underestimate or overestimate total energy expenditure from treadmill walking and running

    Quantum key distribution using non-classical photon number correlations in macroscopic light pulses

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    We propose a new scheme for quantum key distribution using macroscopic non-classical pulses of light having of the order 10^6 photons per pulse. Sub-shot-noise quantum correlation between the two polarization modes in a pulse gives the necessary sensitivity to eavesdropping that ensures the security of the protocol. We consider pulses of two-mode squeezed light generated by a type-II seeded parametric amplification process. We analyze the security of the system in terms of the effect of an eavesdropper on the bit error rates for the legitimate parties in the key distribution system. We also consider the effects of imperfect detectors and lossy channels on the security of the scheme.Comment: Modifications:added new eavesdropping attack, added more references Submitted to Physical Review A [email protected]

    FlashCam: a fully-digital camera for the medium-sized telescopes of the Cherenkov Telescope Array

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    The FlashCam group is currently preparing photomultiplier-tube based cameras proposed for the medium-sized telescopes (MST) of the Cherenkov Telescope Array (CTA). The cameras are designed around the FlashCam readout concept which is the first fully-digital readout system for Cherenkov cameras, based on commercial FADCs and FPGAs as key components for the front-end electronics modules and a high performance camera server as back-end. This contribution describes the progress of the full-scale FlashCam camera prototype currently under construction, as well as performance results also obtained with earlier demonstrator setups. Plans towards the production and implementation of FlashCams on site are also briefly presented.Comment: 8 pages, 6 figures. In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

    Characterization of the Inner Knot of the Crab: The Site of the Gamma-ray Flares?

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    One of the most intriguing results from the gamma-ray instruments in orbit has been the detection of powerful flares from the Crab Nebula. These flares challenge our understanding of pulsar wind nebulae and models for particle acceleration. We report on the portion of a multiwavelength campaign using Keck, HST, and Chandra concentrating on a small emitting region, the Crab's inner knot, located a fraction of an arcsecond from the pulsar. We find that the knot's radial size, tangential size, peak flux, and the ratio of the flux to that of the pulsar are correlated with the projected distance of the knot from the pulsar. A new approach, using singular value decomposition for analyzing time series of images, was introduced yielding results consistent with the more traditional methods while some uncertainties were substantially reduced. We exploit the characterization of the knot to discuss constraints on standard shock-model parameters that may be inferred from our observations assuming the inner knot lies near to the shocked surface. These include inferences as to wind magnetization, shock shape parameters such as incident angle and poloidal radius of curvature, as well as the IR/optical emitting particle enthalpy fraction. We find that while the standard shock model gives good agreement with observation in many respects, there remain two puzzles: (a) The observed angular size of the knot relative to the pulsar--knot separation is much smaller than expected; (b) The variable, yet high degree of polarization reported is difficult to reconcile with a highly relativistic downstream flow.Comment: 46 pages, 14 figures, submitted to the Astrophysical Journa

    Performance Verification of the FlashCam Prototype Camera for the Cherenkov Telescope Array

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    The Cherenkov Telescope Array (CTA) is a future gamma-ray observatory that is planned to significantly improve upon the sensitivity and precision of the current generation of Cherenkov telescopes. The observatory will consist of several dozens of telescopes with different sizes and equipped with different types of cameras. Of these, the FlashCam camera system is the first to implement a fully digital signal processing chain which allows for a traceable, configurable trigger scheme and flexible signal reconstruction. As of autumn 2016, a prototype FlashCam camera for the medium-sized telescopes of CTA nears completion. First results of the ongoing system tests demonstrate that the signal chain and the readout system surpass CTA requirements. The stability of the system is shown using long-term temperature cycling.Comment: 5 pages, 13 figures, Proceedings of the 9th International Workshop on Ring Imaging Cherenkov Detectors (RICH 2016), Lake Bled, Sloveni

    Intensification of hydrological drought in California by human water management

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    We analyze the contribution of human water management to the intensification and mitigation of hydrological drought over California using the PCR-GLOBWB hydrological model for the period 1979-2014. We demonstrate that considering water management results in more accurate discharge representation. During the severe 2014 drought, water management alleviated the drought deficit by ∼50% in Southern California through reservoir operation during low flow periods. However, human water consumption (mostly irrigation) in the Central Valley increased drought duration and deficit by 50% and 50-100%, respectively. Return level analysis indicates that there is more than 50% chance that the probability of occurrence of an extreme 2014-magnitude drought event was at least doubled under the influence of human activities compared to natural variability. This impact is most significant over the San Joaquin Drainage basin with a 50% and 75% likelihood that the return period is more than 3.5 and 1.5 times larger, respectively, because of human activities
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