387 research outputs found
Determining the effects of cattle grazing treatments on Yosemite toads (Anaxyrus [=Bufo] canorus) in montane meadows.
Amphibians are experiencing a precipitous global decline, and population stability on public lands with multiple uses is a key concern for managers. In the Sierra Nevada Mountains (California, USA), managers have specifically identified livestock grazing as an activity that may negatively affect Yosemite toads due to the potential overlap of grazing with toad habitat. Grazing exclusion from Yosemite toad breeding and rearing areas and/or entire meadows have been proposed as possible management actions to alleviate the possible impact of cattle on this species. The primary objective of this study was to determine if different fencing treatments affect Yosemite toad populations. We specifically examined the effect of three fencing treatments on Yosemite toad breeding pool occupancy, tadpoles, and young of the year (YOY). Our hypothesis was that over the course of treatment implementation (2006 through 2010), Yosemite toad breeding pool occupancy and early life stage densities would increase within two fencing treatments relative to actively grazed meadows due to beneficial changes to habitat quality in the absence of grazing. Our results did not support our hypothesis, and showed no benefit to Yosemite toad presence or early life stages in fenced or partially fenced meadows compared to standard USDA Forest Service grazing levels. We found substantial Yosemite toad variation by both meadow and year. This variation was influenced by meadow wetness, with water table depth significant in both the tadpole and YOY models
NLTE effects on Fe I/II in the atmospheres of FGK stars and application to abundance analysis of their spectra
We describe the first results from our project aimed at large-scale
calculations of NLTE abundance corrections for important astrophysical atoms
and ions. In this paper, the focus is on Fe which is a proxy of stellar
metallicity and is commonly used to derive effective temperature and gravity.
We present a small grid of NLTE abundance corrections for Fe I lines and
discuss how NLTE effects influence determination of effective temperature,
surface gravity, and metallicity for late-type stars.Comment: 6 pages, to be published in IOP The Journal of Physics: Conference
Series, proceedings of the Workshop: 'Stellar Atmospheres in the Gaia Era:
Quantitative Spectroscopy and Comparative Spectrum Modelling', Brussels, June
201
Systematic and Controllable Negative, Zero, and Positive Thermal Expansion in Cubic Zr1–xSnxMo2O8
We describe the synthesis and characterization of a family of materials, Zr1–xSnxMo2O8 (0 < x < 1), whose isotropic thermal expansion coefficient can be systematically varied from negative to zero to positive values. These materials allow tunable expansion in a single phase as opposed to using a composite system. Linear thermal expansion coefficients, αl, ranging from −7.9(2) × 10–6 to +5.9(2) × 10–6 K–1 (12–500 K) can be achieved across the series; contraction and expansion limits are of the same order of magnitude as the expansion of typical ceramics. We also report the various structures and thermal expansion of “cubic” SnMo2O8, and we use time- and temperature-dependent diffraction studies to describe a series of phase transitions between different ordered and disordered states of this material
A Radio Monitoring Survey of Ultra-Luminous X-Ray Sources
We present the results of a radio monitoring campaign to search for radio
emission from nearby ultra-luminous X-ray sources (ULXs). These sources are
bright off-nuclear X-ray point sources with luminosities exceeding L_X > 10^39
erg/sec. A well-defined sample of the 9 nearest ULXs has been monitored eight
times during 5 months with the Very Large Array in A and B configuration. Our
limiting sensitivity is approximately 0.15 mJy (4 sigma) for radio flares and
around 60 uJy for continuous emission. In M82 two ULXs seem to have coincident
compact radio sources, which are probably supernova remnants. No continuous or
flaring radio emission has been detected from any other ULX. Thus, ULXs do not
generally emit steady-state radio emission above radio powers of 1.5 10^17
W/Hz. The non-detections of the continuous emission are consistent with beamed
or unbeamed radio emission from accreting black holes of <= 10^3 Msol based on
the radio/X-ray correlation. Other published radio detections (M82, NGC 5408)
are also discussed in this context. Both detections are significantly above our
detection limit. If ULXs have flaring radio emission above 4 10^17 W/Hz we can
give an upper limit on the duty circle of the flares of 6%. This upper limit is
in agreement with the observed number of flares in Galactic radio transients.
Additionally we present a yet unreported radio double structure in the nearby
low-luminosity AGN NGC 4736.Comment: Accepted for publication in A&A, 11 pages, 4 figure
The Gaia-ESO Survey : The analysis of high-resolution UVES spectra of FGK-type stars
Date of Acceptance: 01/09/2014Context. The ongoing Gaia-ESO Public Spectroscopic Survey is using FLAMES at the VLT to obtain high-quality medium-resolution Giraffe spectra for about 105 stars and high-resolution UVES spectra for about 5000 stars. With UVES, the Survey has already observed 1447 FGK-type stars. Aims. These UVES spectra are analyzed in parallel by several state-of-the-art methodologies. Our aim is to present how these analyses were implemented, to discuss their results, and to describe how a final recommended parameter scale is defined. We also discuss the precision (method-to-method dispersion) and accuracy (biases with respect to the reference values) of the final parameters. These results are part of the Gaia-ESO second internal release and will be part of its first public release of advanced data products. Methods. The final parameter scale is tied to the scale defined by the Gaia benchmark stars, a set of stars with fundamental atmospheric parameters. In addition, a set of open and globular clusters is used to evaluate the physical soundness of the results. Each of the implemented methodologies is judged against the benchmark stars to define weights in three different regions of the parameter space. The final recommended results are the weighted medians of those from the individual methods. Results. The recommended results successfully reproduce the atmospheric parameters of the benchmark stars and the expected Teff-log g relation of the calibrating clusters. Atmospheric parameters and abundances have been determined for 1301 FGK-type stars observed with UVES. The median of the method-to-method dispersion of the atmospheric parameters is 55 K for Teff, 0.13 dex for log g and 0.07 dex for [Fe/H]. Systematic biases are estimated to be between 50-100 K for Teff, 0.10-0.25 dex for log g and 0.05-0.10 dex for [Fe/H]. Abundances for 24 elements were derived: C, N, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ba, Nd, and Eu. The typical method-to-method dispersion of the abundances varies between 0.10 and 0.20 dex. Conclusions. The Gaia-ESO sample of high-resolution spectra of FGK-type stars will be among the largest of its kind analyzed in a homogeneous way. The extensive list of elemental abundances derived in these stars will enable significant advances in the areas of stellar evolution and Milky Way formation and evolution.Peer reviewe
Recommended from our members
An eye-movement study of relational memory in adults with Autism Spectrum Disorder
Persons with Autism Spectrum Disorder (ASD) demonstrate good memory for single items but difficulties remembering contextual information related to these items. Recently, we found compromised explicit but intact implicit retrieval of object-location information in ASD (Ring et al. 2015). Eye-movement data collected from a sub-sample of the participants are the focus of the current paper. At encoding, trial-by-trial viewing durations predicted subsequent retrieval success only in typically developing (TD) participants. During retrieval, TD compared to ASD participants looked significantly longer at previously studied objectlocations compared to alternative locations. These findings extend similar observations recently reported by Cooper et al. (2017a) and demonstrate that eye-movement data can shed important light on the source and nature of relational memory difficulties in ASD
Recommended from our members
Recall of a live and personally experienced eyewitness event by adults with autism spectrum disorder
The aim of the present study was to (a) extend previous eyewitness research in autism spectrum disorder (ASD) using a live and personally experienced event; (b) examine whether witnesses with ASD demonstrate a facilitative effect in memory for self- over other-performed actions; (c) explore source monitoring abilities by witnesses with ASD in discriminating who performed which actions within the event. Eighteen high-functioning adults with ASD and 18 age- and IQ-matched typical counterparts participated in a live first aid scenario in which they and the experimenter each performed a number of actions. Participants were subsequently interviewed for their memory of the event using a standard interview procedure with free recall followed by questioning. The ASD group recalled just as many correct details as the comparison group from the event overall, however they made more errors. This was the case across both free recall and questioning phases. Both groups showed a self-enactment effect across both interview phases, recalling more actions that they had performed themselves than actions that the experimenter had performed. However, the ASD group were more likely than their typical comparisons to confuse the source of self-performed actions in free recall, but not in questioning, which may indicate executive functioning difficulties with unsupported test procedures. Findings are discussed in terms of their theoretical and practical implications
The initial characterization of the iron environment in lipoxygenase by MÖssbauer spectroscopy
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65879/1/j.1432-1033.1990.tb15616.x.pd
Recommended from our members
Eyewitness Testimony in Autism Spectrum Disorder: A Review
Autism spectrum disorder (ASD) is estimated to affect around 1% of the population, and is characterised by impairments in social interaction, communication, and behavioural flexibility. A number of risk factors indicate that individuals with ASD may become victims or witnesses of crimes. In addition to their social and communication deficits, people with ASD also have very specific memory problems, which impacts on their abilities to recall eyewitnessed events. We begin this review with an overview of the memory difficulties that are experienced by individuals with ASD, before discussing the studies that have specifically examined eyewitness testimony in this group and the implications for investigative practice. Finally, we outline related areas that would be particularly fruitful for future research to explore
- …