5,246 research outputs found
The influence of risk factors associated with captive rearing on post-release survival in translocated cirl buntings Emberiza cirlus in the UK
Population decline resulting from agricultural intensification led to contraction of the range of the cirl bunting Emberiza cirlus in the UK to a small area of south Devon. As part of the UK Biodiversity Action Plan for the species, a project to re-establish a population in suitable habitat in Cornwall was undertaken during 2006â2011, in which chicks were removed from the nest in Devon, hand-reared and then delayed-released. The survival of the birds to four time points in the year after release was analysed in relation to the effect of rearing factors, using a multivariable logistic regression model. Individuals with higher body weight at capture were more likely to survive to 1 January and 1 May in the year following release, and individuals released in June and July were more likely to survive than those released in August. Individuals released in 2006 and 2011 had a higher survival rate than those released during 2007â2010. Timing of capture, time spent at each stage in captivity, medication and the detection of parasites in the brood had no significant effect. Immunosuppressive disease, weather factors and predator activity may have led to some of the observed differences in survival. This analysis provides evidence with which to plan future translocation projects for cirl buntings and other passerine birds
Correlation Function of Galaxy Groups
We use the Updated Zwicky Catalog of galaxies (Falco et al. 1999) to generate
a catalog of groups, by means of a friend-of-friend algorithm. The correlation
length of the total sample is well fitted with a power law with parameters and for values of . Three subsamples defined by
the range of group virial masses were used to have their clustering
properties examined throughout the autocorrelation function. We find an
increase of the amplitude of the correlation function according to the group
masses which extends the results of the relation for galaxy systems
at small . For completeness we have also analyzed a sample of groups
obtained from the Southern Sky Redshift Survey (da Costa et al.1998) in the
range of virial masses to compare the results with those obtained from
GUZC.Comment: 9 figures, accepted for publication in Ap
Cosmological Limits on the Neutrino Mass from the Lya Forest
The Lya forest in quasar spectra probes scales where massive neutrinos can
strongly suppress the growth of mass fluctuations. Using hydrodynamic
simulations with massive neutrinos, we successfully test techniques developed
to measure the mass power spectrum from the forest. A recent observational
measurement in conjunction with a conservative implementation of other
cosmological constraints places upper limits on the neutrino mass: m_nu < 5.5
eV for all values of Omega_m, and m_nu < 2.4 (Omega_m/0.17 -1) eV, if 0.2 <
Omega_m <0.5 as currently observationally favored (both 95 % C.L.).Comment: 4 pages, 2 ps figures, REVTex, submitted to Phys. Rev. Let
Warm-Hot Gas in and around the Milky Way: Detection and Implications of OVII Absorption toward LMC X-3
X-ray absorption lines of highly-ionized species such as OVII at about zero
redshift have been firmly detected in the spectra of several active galactic
nuclei. However, the location of the absorbing gas remains a subject of debate.
To separate the Galactic and extragalactic contributions to the absorption, we
have obtained Chandra LETG-HRC and FUSE observations of the black hole X-ray
binary LMC X--3. A joint analysis of the detected OVII and Ne IX Kalpha lines,
together with the non-detection of the OVII Kbeta and OVIII Kalpha lines, gives
the measurements of the temperature, velocity dispersion, and hot oxygen column
density. The X-ray data also allow us to place a 95% confidence lower limit to
the Ne/O ratio as 0.14. The OVII line centroid and its relative shift from the
Galactic OI Kalpha absorption line, detected in the same observations, are
inconsistent with the systemic velocity of LMC X--3 ().
The far-UV spectrum shows OVI absorption at Galactic velocities, but no OVI
absorption is detected at the LMC velocity at significance. Both
the nonthermal broadening and the decreasing scale height with the increasing
ionization state further suggest an origin of the highly-ionized gas in a
supernova-driven galactic fountain. In addition, we estimate the warm and hot
electron column densities from our detected OVII Kalpha line in the LMC X--3
X-ray spectra and from the dispersion measure of a pulsar in the LMC vicinity.
We then infer the O/H ratio of the gas to be ,
consistent with the chemically-enriched galactic fountain scenario. We conclude
that the Galactic hot interstellar medium should in general substantially
contribute to zero-redshift X-ray absorption lines in extragalactic sources.Comment: 11 pages, accepted for publication in Ap
#Bieber + #Blast = #BieberBlast: Early Prediction of Popular Hashtag Compounds
Compounding of natural language units is a very common phenomena. In this
paper, we show, for the first time, that Twitter hashtags which, could be
considered as correlates of such linguistic units, undergo compounding. We
identify reasons for this compounding and propose a prediction model that can
identify with 77.07% accuracy if a pair of hashtags compounding in the near
future (i.e., 2 months after compounding) shall become popular. At longer times
T = 6, 10 months the accuracies are 77.52% and 79.13% respectively. This
technique has strong implications to trending hashtag recommendation since
newly formed hashtag compounds can be recommended early, even before the
compounding has taken place. Further, humans can predict compounds with an
overall accuracy of only 48.7% (treated as baseline). Notably, while humans can
discriminate the relatively easier cases, the automatic framework is successful
in classifying the relatively harder cases.Comment: 14 pages, 4 figures, 9 tables, published in CSCW (Computer-Supported
Cooperative Work and Social Computing) 2016. in Proceedings of 19th ACM
conference on Computer-Supported Cooperative Work and Social Computing (CSCW
2016
IoTSan: Fortifying the Safety of IoT Systems
Today's IoT systems include event-driven smart applications (apps) that
interact with sensors and actuators. A problem specific to IoT systems is that
buggy apps, unforeseen bad app interactions, or device/communication failures,
can cause unsafe and dangerous physical states. Detecting flaws that lead to
such states, requires a holistic view of installed apps, component devices,
their configurations, and more importantly, how they interact. In this paper,
we design IoTSan, a novel practical system that uses model checking as a
building block to reveal "interaction-level" flaws by identifying events that
can lead the system to unsafe states. In building IoTSan, we design novel
techniques tailored to IoT systems, to alleviate the state explosion associated
with model checking. IoTSan also automatically translates IoT apps into a
format amenable to model checking. Finally, to understand the root cause of a
detected vulnerability, we design an attribution mechanism to identify
problematic and potentially malicious apps. We evaluate IoTSan on the Samsung
SmartThings platform. From 76 manually configured systems, IoTSan detects 147
vulnerabilities. We also evaluate IoTSan with malicious SmartThings apps from a
previous effort. IoTSan detects the potential safety violations and also
effectively attributes these apps as malicious.Comment: Proc. of the 14th ACM CoNEXT, 201
Observation of Changes in the Atomic and Electronic Structure of Single-Crystal YBaâCuâOâ.â Accompanying Bromination
To ascertain the role of bromination in the recovery of superconductivity in underdoped YBa2Cu3O6+y (YBCO), we have performed polarized multiple-edge x-ray-absorption fine structure (XAFS) measurements on normal (y~0.6) and brominated (Br/Cu~1/30, y~0.6) single crystals with superconducting transitions at 63 and 89 K, respectively. The brominated sample becomes strongly heterogeneous on an atomic length scale. Approximately one-third of YBCO is locally decomposed yet incorporated as a well-ordered host lattice as nanoscale regions. The decomposed phase consists of heavily distorted domains with an order not following that of the host lattice. Structurally, these domains are fragments of the YBCO lattice that are discontinued along the Cu(1)-O(1) containing planes. The local structure is consistent with the cluster expansions: Y-O(2,3)8-Cu(2)8-..., Ba-O8-Cu(2)4Cu(1)2-..., and Cu-O4... about the Y, Ba, and Cu sites. Interatomic distances and Debye-Waller factors for the expansions were determined from fits to Y K-, Ba L3-, and Cu K-edge XAFS data at room temperature. Br K-edge data reveal that Br does not enter substitutionally or interstitially into the perfect YBCO lattice. However, Br does occupy the Cu(1) sites in a nanofragment of the YBCO lattice, forming Br-O(4)-Ba-Cu2(1)Cu(2)-... nanoclusters. From polarized measurements these nanoclusters were found to be almost randomly oriented with respect to the host crystal, and probably are the nucleus of the decomposed phase. This heterogeneity brings about the unusual structural and electronic properties of the normal state previously reported in the literature. Implications on for diffraction, transport, and magnetization measurements are discussed
The redshift-space two-point correlation functions of galaxies and groups in the Nearby Optical Galaxy sample
We use the two-point correlation function in redshift space, , to
study the clustering of the galaxies and groups of the Nearby Optical Galaxy
(NOG) sample, which is a nearly all-sky, complete, magnitude-limited sample of
7000 bright and nearby optical galaxies. The correlation function of
galaxies is well described by a power law, , with
slope and Mpc (on scales Mpc), in agreement with previous results of several redshift surveys of
optical galaxies. We confirm the existence of morphological segregation between
early- and late-type galaxies and, in particular, we find a gradual decreasing
of the strength of clustering from the S0 galaxies to the late-type spirals, on
intermediate scales. Furthermore, luminous galaxies turn out to be more
clustered than dim galaxies. The luminosity segregation, which is significant
for both early- and late-type objects, starts to become appreciable only for
galaxies brighter than () and is
independent on scale. The NOG group correlation functions are characterized by
-values ranging from Mpc (for groups with at least three
members) to Mpc (for groups with at least five members). The
degree of group clustering depends on the physical properties of groups.
Specifically, groups with greater velocity dispersions, sizes and masses tend
to be more clustered than those with lower values of these quantities.Comment: Astrophysical Journal, in press, 72 pages, 16 eps figure
Technique for Direct eV-Scale Measurements of the Mu and Tau Neutrino Masses Using Supernova Neutrinos
Early black hole formation in a core-collapse supernova will abruptly
truncate the neutrino fluxes. The sharp cutoff can be used to make
model-independent time-of-flight neutrino mass tests. Assuming a neutrino
luminosity of erg/s per flavor at cutoff and a distance of 10 kpc,
SuperKamiokande can detect an electron neutrino mass as small as 1.8 eV, and
the proposed OMNIS detector can detect mu and tau neutrino masses as small as 6
eV. This {\it Letter} presents the first technique with direct sensitivity to
eV-scale mu and tau neutrino masses.Comment: 4 pages including 3 inline figures. Submitted to Physical Review
Letter
Constraints on the Neutrino Mass from SZ Surveys
Statistical measures of galaxy clusters are sensitive to neutrino masses in
the sub-eV range. We explore the possibility of using cluster number counts
from the ongoing PLANCK/SZ and future cosmic-variance-limited surveys to
constrain neutrino masses from CMB data alone. The precision with which the
total neutrino mass can be determined from SZ number counts is limited mostly
by uncertainties in the cluster mass function and intracluster gas evolution;
these are explicitly accounted for in our analysis. We find that projected
results from the PLANCK/SZ survey can be used to determine the total neutrino
mass with a (1\sigma) uncertainty of 0.06 eV, assuming it is in the range
0.1-0.3 eV, and the survey detection limit is set at the 5\sigma significance
level. Our results constitute a significant improvement on the limits expected
from PLANCK/CMB lensing measurements, 0.15 eV. Based on expected results from
future cosmic-variance-limited (CVL) SZ survey we predict a 1\sigma uncertainty
of 0.04 eV, a level comparable to that expected when CMB lensing extraction is
carried out with the same experiment. A few percent uncertainty in the mass
function parameters could result in up to a factor \sim 2-3 degradation of our
PLANCK and CVL forecasts. Our analysis shows that cluster number counts provide
a viable complementary cosmological probe to CMB lensing constraints on the
total neutrino mass.Comment: Replaced with a revised version to match the MNRAS accepted version.
arXiv admin note: text overlap with arXiv:1009.411
- âŠ