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
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
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
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
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
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 1979â2015 on eight Wildlife Management Areas (WMAs) in the north Georgia mountains. During 1979â2015, 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 (0â10 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 2003â2015. 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 (0â10 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
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, ; 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
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
() and the integrated dust content ().
We select a sample of 163 galaxies between with H
signal-to-noise ratio and measure Balmer decrements from stacked spectra
to calculate . First, we stack spectra in bins of
, and find that
, with a significance of
. 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 (),
star formation rate (), and stellar mass (). We
find that on average 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 H
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
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: 1.5â3.5+ years old) harvested between 1997â2016 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
AIM: To assess patientâreported 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: 2017â003370â13), a 26âweek, openâlabel study, randomized (1:1) 887 adults with T2D and HbA1c â„7.5%ââ€10.0% (â„58ââ€86 mmol/mol) on basal insulin plus oral antihyperglycaemic drugs (OADs) to onceâdaily iGlarLixi or twiceâdaily premix insulin, BIAsp 30. PROs were assessed using the TreatmentâRelated Impact Measure Diabetes (TRIMâD) and Global Treatment Effectiveness Evaluation (GTEE) questionnaires. RESULTS: Over 26âweeks, iGlarLixi showed greater improvement from baseline versus BIAsp 30 in total TRIMâD score (least squares mean difference [95% confidence interval]: 5.08 [3.69, 6.47]; effect size: 0.32) and in each TRIMâD 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 TRIMâD total scores versus BIAsp 30. CONCLUSIONS: In addition to better glycaemic control, weight benefit and less hypoglycaemia, onceâdaily iGlarLixi provided improved diabetes management, treatment burden and perceived effectiveness versus twiceâdaily 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
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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