876 research outputs found

    The Solar Neighborhood XV: Discovery of New High Proper Motion Stars with mu >= 0.4"/yr between Declinations -47 degrees and 00 degrees

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    We report the discovery of 152 new high proper motion systems (mu >= 0.4"/yr) in the southern sky (Declination = -47 degrees to 00 degrees) brighter than UKST plate R_{59F} =16.5 via our SuperCOSMOS-RECONS (SCR) search. This paper complements Paper XII in The Solar Neighborhood series, which covered the region from Declination = -90 degrees to -47 degrees and discussed all 147 new systems from the southernmost phase of the search. Among the total of 299 systems from both papers, there are 148 (71 in Paper XII, 77 in this paper) new systems moving faster than 0.5"/yr that are additions to the classic ``LHS'' (Luyten Half Second) sample. These constitute an 8% increase in the sample of all stellar systems with mu >= 0.5"/yr in the southern sky. As in Paper XII, distance estimates are provided for the systems reported here based upon a combination of photographic plate magnitudes and 2MASS photometry, assuming all stars are on the main sequence. Two SCR systems from the portion of the sky included in this paper are anticipated to be within 10 pc, and an additional 23 are within 25 pc. In total, the results presented in Paper XII and here for this SCR sweep of the entire southern sky include five new systems within 10 pc and 38 more between 10 and 25 pc. The largest number of nearby systems have been found in the slowest proper motion bin, 0.6"/yr > mu >= 0.4"/yr, indicating that there may be a large population of low proper motion systems very near the Sun.Comment: 36 pages, 5 figures, accepted for publication in Astronomical Journa

    Gate Coupling to Nanoscale Electronics

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    The realization of single-molecule electronic devices, in which a nanometer-scale molecule is connected to macroscopic leads, requires the reproducible production of highly ordered nanoscale gaps in which a molecule of interest is electrostatically coupled to nearby gate electrodes. Understanding how the molecule-gate coupling depends on key parameters is crucial for the development of high-performance devices. Here we directly address this, presenting two- and three-dimensional finite-element electrostatic simulations of the electrode geometries formed using emerging fabrication techniques. We quantify the gate coupling intrinsic to these devices, exploring the roles of parameters believed to be relevant to such devices. These include the thickness and nature of the dielectric used, and the gate screening due to different device geometries. On the single-molecule (~1nm) scale, we find that device geometry plays a greater role in the gate coupling than the dielectric constant or the thickness of the insulator. Compared to the typical uniform nanogap electrode geometry envisioned, we find that non-uniform tapered electrodes yield a significant three orders of magnitude improvement in gate coupling. We also find that in the tapered geometry the polarizability of a molecular channel works to enhance the gate coupling

    Applying Model-based Diagnosis to a Rapid Propellant Loading System

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    The overall objective of the US Air Force Research Laboratory (AFRL) Rapid Propellant Loading (RPL) Program is to develop a launch vehicle, payload and ground support equipment that can support a rapid propellant load and launch within one hour. NASA Kennedy Space Center (KSC) has been funded by AFRL to develop hardware and software to demonstrate this capability. The key features of the software would be the ability to recognize and adapt to failures in the physical hardware components, advise operators of equipment faults and workarounds, and put the system in a safe configuration if unable to fly. In December 2008 NASA KSC and NASA Ames Research Center (ARC) demonstrated model based simulation and diagnosis capabilities for a scaled-down configuration of the RPL hardware. In this paper we present a description of the model-based technologies that were included as part of this demonstration and the results that were achieved. In continuation of this work we are currently testing the technologies on a simulation of the complete RPL system. Later in the year, when the RPL hardware is ready, we will be integrating these technologies with the real-time operation of the system to provide live state estimates. In future years we will be developing the capability to recover from faulty conditions via redundancy and reconfiguration

    Structural and magnetic properties of E-Fe_{1-x}Co_xSi thin films deposited via pulsed laser deposition

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    We report pulsed laser deposition synthesis and characterization of polycrystalline Fe1-xCox Si thin films on Si (111). X-ray diffraction, transmission electron, and atomic force microscopies reveal films to be dense, very smooth, and single phase with a cubic B20 crystal structure. Ferromagnetism with significant magnetic hysteresis is found for all films including nominally pure FeSi films in contrast to the very weak paramagnetism of bulk FeSi. For Fe1-xCoxSi this signifies a change from helimagnetism in bulk, to ferromagnetism in thin films. These ferromagnetic thin films are promising as a magnetic-silicide/silicon system for polarized current production, manipulation, and detection.Comment: 12 pages, 4 figures accepted in the Applied Physics Letter

    Understanding Deer, Bear, and Forest Trends in the North Georgia Mountains: The Value of Long-term Data

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    Most state wildlife agencies collect harvest data to inform management decisions. However, these data are typically considered across relatively short time periods and are rarely revisited. We present a case study using historical records to investigate potential agents (i.e., harvest, predation, and forest change) influencing the declining white-tailed deer (Odocoileus virginianus) population in the north Georgia mountains. We used long-term black bear (Ursus americanus) and deer harvest data, and indices of forest stand conditions from 1979–2015 on eight Wildlife Management Areas (WMAs) in the north Georgia mountains. During 1979–2015, harvest of male and female deer declined by 85% and 97%, respectively. Over the same time period, mean yearling male deer body weight increased by 21%, mean antler diameter increased by 62%, and mean antler beam length increased by 92%. We observed a 97% reduction in availability of early successional forests (0–10 years old) and a 53% increase in volume of large diameter (\u3e27.9 cm) oak species, suggesting increasing homogeneity/maturation of forest stands across all eight WMAs. Concomitantly, the U.S. Forest Service increased the acreage under prescribed fire management from 2,916 to 5,629 ha during 2003–2015. Black bear populations grew at an annual rate of 1.07 for males and 1.08 for females. Our analyses indicated that despite the reduction in early successional habitats as illustrated by the reduction in young forests (0–10 years old), deer condition indices have improved suggesting that a habitat-driven change in fecundity was not the likely primary driver of the deer population decline. However, increasing fawn predation, coupled with a decline in available fawning cover may be reducing recruitment rates and should be investigated as potential causes for the observed population decline. Our research also illustrates the importance of maintaining longterm data, especially the value offered to evaluate trends over time

    The DEEP2 Galaxy Redshift Survey: The Evolution of Void Statistics from z~1 to z~0

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    We present measurements of the void probability function (VPF) at z~1 using data from the DEEP2 Redshift Survey and its evolution to z~0 using data from the Sloan Digital Sky Survey (SDSS). We measure the VPF as a function of galaxy color and luminosity in both surveys and find that it mimics trends displayed in the two-point correlation function, Ο\xi; namely that samples of brighter, red galaxies have larger voids (i.e. are more strongly clustered) than fainter, blue galaxies. We also clearly detect evolution in the VPF with cosmic time, with voids being larger in comoving units at z~0. We find that the reduced VPF matches the predictions of a `negative binomial' model for galaxies of all colors, luminosities, and redshifts studied. This model lacks a physical motivation, but produces a simple analytic prediction for sources of any number density and integrated two-point correlation function, \bar{\xi}. This implies that differences in the VPF across different galaxy populations are consistent with being due entirely to differences in the population number density and \bar{\xi}. The robust result that all galaxy populations follow the negative binomial model appears to be due to primarily to the clustering of dark matter halos. The reduced VPF is insensitive to changes in the parameters of the halo occupation distribution, in the sense that halo models with the same \bar{\xi} will produce the same VPF. For the wide range of galaxies studied, the VPF therefore does not appear to provide useful constraints on galaxy evolution models that cannot be gleaned from studies of \bar{\xi} alone. (abridged)Comment: 17 pages, 15 figures, ApJ accepte

    Direct measurements of dust attenuation in z~1.5 star-forming galaxies from 3D-HST: Implications for dust geometry and star formation rates

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    The nature of dust in distant galaxies is not well understood, and until recently few direct dust measurements have been possible. We investigate dust in distant star-forming galaxies using near-infrared grism spectra of the 3D-HST survey combined with archival multi-wavelength photometry. These data allow us to make a direct comparison between dust around star-forming regions (AV,HIIA_{V,\mathrm{HII}}) and the integrated dust content (AV,starA_{V,\mathrm{star}}). We select a sample of 163 galaxies between 1.36≀z≀1.51.36\le{}z\le1.5 with Hα\alpha signal-to-noise ratio ≄5\ge5 and measure Balmer decrements from stacked spectra to calculate AV,HIIA_{V,\mathrm{HII}}. First, we stack spectra in bins of AV,starA_{V,\mathrm{star}}, and find that AV,HII=1.86 AV,starA_{V,\mathrm{HII}}=1.86\,A_{V,\mathrm{star}}, with a significance of σ=1.7\sigma=1.7. Our result is consistent with the two-component dust model, in which galaxies contain both diffuse and stellar birth cloud dust. Next, we stack spectra in bins of specific star formation rate (log⁡ SSFR\log\,\mathrm{SSFR}), star formation rate (log⁡ SFR\log\,\mathrm{SFR}), and stellar mass (log⁥M∗\log{}M_*). We find that on average AV,HIIA_{V,\mathrm{HII}} increases with SFR and mass, but decreases with increasing SSFR. Interestingly, the data hint that the amount of extra attenuation decreases with increasing SSFR. This trend is expected from the two-component model, as the extra attenuation will increase once older stars outside the star-forming regions become more dominant in the galaxy spectrum. Finally, using Balmer decrements we derive dust-corrected Hα\alpha SFRs, and find that stellar population modeling produces incorrect SFRs if rapidly declining star formation histories are included in the explored parameter space.Comment: Accepted for publication in the Astrophysical Journal (13 pages, 9 figures

    Variation in White-tailed Deer Antler Size: The Effects of Age, Landscape Composition, and Physiographic Province

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    Spatial variation in landscape composition can influence phenotypic expression in wildlife species and can improve management efforts to express certain phenotypic traits. We evaluated the influence of age, landscape composition, and physiographic province on white-tailed deer (Odocoileus virginianus) antler characteristics using data from 16,622 male deer (age range: 1.5–3.5+ years old) harvested between 1997–2016 across five physiographic provinces in Georgia. Age and physiographic province influenced antler size index (ASI; P \u3c 0.001). ASI of yearling males was greatest (- x = 53.37; SE = 0.39) in the Upper Coastal Plain and least (- x = 46.23; SE = 0.51) in the Lower Coastal Plain physiographic province. Given the differences in ASI among physiographic provinces, we evaluated how landscape composition within each physiographic province influenced ASI of 7,325 yearling (1.5-year-old) males. Yearling ASI was positively related to increasing coverage of cultivated crops and suburban-urban areas (e.g., parks, small housing developments). Conversely, evergreen and deciduous forested cover consistently had a negative effect on ASI, except in the Ridge and Valley physiographic province where evergreen was positively related to ASI. Wildlife managers and hunters should recognize the effects of age, landscape composition, and physiographic province when setting antler size expectations

    Improved patient-reported outcomes with iGlarLixi versus premix BIAsp 30 in people with type 2 diabetes in the SoliMix trial

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    AIM: To assess patient‐reported outcomes (PROs) in the SoliMix trial, which compared the efficacy and safety of iGlarLixi versus BIAsp 30 in people with type 2 diabetes (T2D). MATERIALS AND METHODS: SoliMix (EudraCT: 2017‐003370‐13), a 26‐week, open‐label study, randomized (1:1) 887 adults with T2D and HbA1c ≄7.5%‐≀10.0% (≄58‐≀86 mmol/mol) on basal insulin plus oral antihyperglycaemic drugs (OADs) to once‐daily iGlarLixi or twice‐daily premix insulin, BIAsp 30. PROs were assessed using the Treatment‐Related Impact Measure Diabetes (TRIM‐D) and Global Treatment Effectiveness Evaluation (GTEE) questionnaires. RESULTS: Over 26 weeks, iGlarLixi showed greater improvement from baseline versus BIAsp 30 in total TRIM‐D score (least squares mean difference [95% confidence interval]: 5.08 [3.69, 6.47]; effect size: 0.32) and in each TRIM‐D domain, with the greatest differences seen in diabetes management (8.47 [6.11, 10.84]) and treatment burden (6.95 [4.83, 9.07]). GTEE scores showed a greater proportion of participants and physicians rated a complete or marked improvement of diabetes control with iGlarLixi (80.5%, 82.8%) versus BIAsp 30 (63.3%, 65.1%) at week 26. Post hoc analyses showed that after adjusting for HbA1c, body weight and hypoglycaemia outcomes, iGlarLixi continued to show greater improvements in TRIM‐D total scores versus BIAsp 30. CONCLUSIONS: In addition to better glycaemic control, weight benefit and less hypoglycaemia, once‐daily iGlarLixi provided improved diabetes management, treatment burden and perceived effectiveness versus twice‐daily premix BIAsp 30, further supporting iGlarLixi as an advanced treatment option in people with suboptimally controlled T2D on basal insulin plus OADs

    How to Reduce Aflatoxin Contamination in Groundnuts and Maize A Guide for Extension Workers

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    Many agricultural commodities are susceptible to several diseases caused by fungi, viruses and insect pests. These diseases may also contaminate the crops with deadly toxins. Fungi are of particular concern. Many fungi are free-living organisms capable of surviving in the environment (soil, air and water) and can easily find their way into crop products especially when the weather conditions are suitable. Many of these fungi are free-living organisms and can survive in the environment even without the crops we grow. The toxins produced by fungi are called mycotoxins (Myco=fungus; toxin=poison)..
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