1,149 research outputs found
Interactions In Space For Archaeological Models
In this article we examine a variety of quantitative models for describing
archaeological networks, with particular emphasis on the maritime networks of
the Aegean Middle Bronze Age. In particular, we discriminate between those
gravitational networks that are most likely (maximum entropy) and most
efficient (best cost/benefit outcomes).Comment: 21 pages, 6 figures, 2 tables. Contribution to special issue of
Advances in Complex Systems from the conference `Cultural Evolution in
Spatially Structured Populations', UCL, London, September 2010. To appear in
Advances in Complex System
AMPHIBIAN AND REPTILE COLONIZATION OF RECLAIMED COAL SPOIL GRASSLANDS
While habitat loss is a major driver of amphibian and reptile declines globally, a subset of post-industrial landscapes, reclaimed and restored, are creating habitat for these animals. In a previous work, we showed that amphibians and reptiles use reclaimed and restored grasslands. In the present work we quantify captures at drift-fence/pitfall trap arrays over two consecutive years and show that several species of amphibians are not only successfully reproducing but that juveniles are being recruited into the population. In particular, 15,844 amphibians and 334 reptiles representing 25 species (14 amphibians, 11 reptiles) were captured at drift fences in 2009 and 2010. Nine additional reptile species were found opportunistically while conducting other research activities at the study site. Out of a total of 8,064 metamorphosing juveniles we detected 126 malformations, a 1.6% rate. The major malformation types were limbs missing (amelia) or foreshortened (ectromely), eye discolorations, and digits foreshortened (ectrodactyly) or small (brachydactyly). Our data show that reclaimed, restored, and properly managed landscapes can support reproducing populations of amphibians and reptiles with low malformation rates, including species in decline across other portions of their range
Constraints of a pulsation frequency on stellar parameters in the eclipsing spectroscopic binary system: V577 Oph
We present a preliminary spectroscopic analysis of the binary system V577Oph,
observed during the summer of 2007 on the 2.6m NOT telescope on La Palma. We
have obtained time series spectroscopic observations, which show clear binary
motion as well as radial velocity variations due to pulsation in the primary
star. By modelling the radial velocities we determine a full orbital solution
of the system, which yields M_A sin^3 i = 1.562 +/- 0.012 M_solar and M_B sin^3
i = 1.461 +/- 0.020 M_solar. An estimate of inclination from photometry yields
a primary mass of 1.6 M_solar. Using this derived mass, and the known pulsation
frequency we can impose a lower limit of 1 Gyr on the age of the system, and
constrain the parameters of the oscillation mode. We show that with further
analysis of the spectra (extracting the atmospheric parameters), tighter
constraints could be imposed on the age, metallicity and the mode parameters.
This work emphasizes the power that a single pulsation frequency can have for
constraining stellar parameters in an eclipsing binary system.Comment: Accepted by A
Anti-neutrophil cytoplasmic autoantibodies induce neutrophils to degranulate and produce oxygen radicals in vitro.
Drosophila modifier screens to identify novel neuropsychiatric drugs including aminergic agents for the possible treatment of Parkinson's disease and depression.
Small molecules that increase the presynaptic function of aminergic cells may provide neuroprotection in Parkinson's disease (PD) as well as treatments for attention deficit hyperactivity disorder (ADHD) and depression. Model genetic organisms such as Drosophila melanogaster may enhance the detection of new drugs via modifier or 'enhancer/suppressor' screens, but this technique has not been applied to processes relevant to psychiatry. To identify new aminergic drugs in vivo, we used a mutation in the Drosophila vesicular monoamine transporter (dVMAT) as a sensitized genetic background and performed a suppressor screen. We fed dVMAT mutant larvae ∼ 1000 known drugs and quantitated rescue (suppression) of an amine-dependent locomotor deficit in the larva. To determine which drugs might specifically potentiate neurotransmitter release, we performed an additional secondary screen for drugs that require presynaptic amine storage to rescue larval locomotion. Using additional larval locomotion and adult fertility assays, we validated that at least one compound previously used clinically as an antineoplastic agent potentiates the presynaptic function of aminergic circuits. We suggest that structurally similar agents might be used to development treatments for PD, depression and ADHD, and that modifier screens in Drosophila provide a new strategy to screen for neuropsychiatric drugs. More generally, our findings demonstrate the power of physiologically based screens for identifying bioactive agents for select neurotransmitter systems
A Search for Hierarchical Triples using Kepler Eclipse Timing
We present the first results of a Kepler survey of 41 eclipsing binaries that
we undertook to search for third star companions. Such tertiaries will
periodically alter the eclipse timings through light travel time and dynamical
effects. We discuss the prevalence of starspots and pulsation among these
binaries and how these phenomena influence the eclipse times. There is no
evidence of short period companions (P < 700 d) among this sample, but we do
find evidence for long term timing variations in 14 targets (34%). We argue
that this finding is consistent with the presence of tertiary companions among
a significant fraction of the targets, especially if many have orbits measured
in decades. This result supports the idea that the formation of close binaries
involves the deposition of angular momentum into the orbital motion of a third
star.Comment: AJ, in press, 104 pages, 2 figure sets plus 1 regular figur
The Interplanetary Network Supplement to the BeppoSAX Gamma-Ray Burst Catalogs
Between 1996 July and 2002 April, one or more spacecraft of the
interplanetary network detected 787 cosmic gamma-ray bursts that were also
detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera
experiments aboard the BeppoSAX spacecraft. During this period, the network
consisted of up to six spacecraft, and using triangulation, the localizations
of 475 bursts were obtained. We present the localization data for these events.Comment: 89 pages, 3 figures. Submitted to the Astrophysical Journal
Supplement Serie
APASS Landolt-Sloan BVgri photometry of RAVE stars. I. Data, effective temperatures and reddenings
We provide APASS photometry in the Landolt BV and Sloan g'r'i' bands for all
the 425,743 stars included in the latest 4th RAVE Data Release. The internal
accuracy of the APASS photometry of RAVE stars, expressed as error of the mean
of data obtained and separately calibrated over a median of 4 distinct
observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012,
0.014 and 0.021 mag for B, V, g', r' and i' band, respectively. The equally
high external accuracy of APASS photometry has been verified on secondary
Landolt and Sloan photometric standard stars not involved in the APASS
calibration process, and on a large body of literature data on field and
cluster stars, confirming the absence of offsets and trends. Compared with the
Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate
to a median value of 0.098 arcsec. Brightness distribution functions for the
RAVE stars have been derived in all bands. APASS photometry of RAVE stars,
augmented by 2MASS JHK infrared data, has been chi2 fitted to a densely
populated synthetic photometric library designed to widely explore in
temperature, surface gravity, metallicity and reddening. Resulting Teff and
E(B-V), computed over a range of options, are provided and discussed, and will
be kept updated in response to future APASS and RAVE data releases. In the
process it is found that the reddening caused by an homogeneous slab of dust,
extending for 140 pc on either side of the Galactic plane and responsible for
E(B-V,poles)=0.036 +/- 0.002 at the galactic poles, is a suitable approximation
of the actual reddening encountered at Galactic latitudes |b|>=25 deg.Comment: Astronomical Journal, in press. Resolution of Figures degrated to
match arXiv file size limit
The local power of the gradient test
The asymptotic expansion of the distribution of the gradient test statistic
is derived for a composite hypothesis under a sequence of Pitman alternative
hypotheses converging to the null hypothesis at rate , being the
sample size. Comparisons of the local powers of the gradient, likelihood ratio,
Wald and score tests reveal no uniform superiority property. The power
performance of all four criteria in one-parameter exponential family is
examined.Comment: To appear in the Annals of the Institute of Statistical Mathematics,
this http://www.ism.ac.jp/editsec/aism-e.htm
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