310 research outputs found
Winter Bird Assemblages in Rural and Urban Environments: A National Survey
Urban development has a marked effect on the ecological and behavioural traits of many living
organisms, including birds. In this paper, we analysed differences in the numbers of wintering
birds between rural and urban areas in Poland. We also analysed species richness
and abundance in relation to longitude, latitude, human population size, and landscape
structure. All these parameters were analysed using modern statistical techniques incorporating
species detectability. We counted birds in 156 squares (0.25 km2 each) in December
2012 and again in January 2013 in locations in and around 26 urban areas across Poland
(in each urban area we surveyed 3 squares and 3 squares in nearby rural areas). The influence
of twelve potential environmental variables on species abundance and richness was
assessed with Generalized Linear Mixed Models, Principal Components and Detrended
Correspondence Analyses. Totals of 72 bird species and 89,710 individual birds were recorded
in this study. On average (±SE) 13.3 ± 0.3 species and 288 ± 14 individuals were recorded
in each square in each survey. A formal comparison of rural and urban areas
revealed that 27 species had a significant preference; 17 to rural areas and 10 to urban areas. Moreover, overall abundance in urban areas was more than double that of rural
areas. There was almost a complete separation of rural and urban bird communities. Significantly
more birds and more bird species were recorded in January compared to December.
We conclude that differences between rural and urban areas in terms of winter conditions
and the availability of resources are reflected in different bird communities in the two
environments
The Morphology of Galaxies in the Baryon Oscillation Spectroscopic Survey
We study the morphology of luminous and massive galaxies at 0.3<z<0.7
targeted in the Baryon Oscillation Spectroscopic Survey (BOSS) using publicly
available Hubble Space Telescope imaging from COSMOS. Our sample (240 objects)
provides a unique opportunity to check the visual morphology of these galaxies
which were targeted based solely on stellar population modelling. We find that
the majority (74+/-6%) possess an early-type morphology (elliptical or S0),
while the remainder have a late-type morphology. This is as expected from the
goals of the BOSS target selection which aimed to predominantly select slowly
evolving galaxies, for use as cosmological probes, while still obtaining a fair
fraction of actively star forming galaxies for galaxy evolution studies. We
show that a colour cut of (g-i)>2.35 selects a sub-sample of BOSS galaxies with
90% early-type morphology - more comparable to the earlier Luminous Red Galaxy
(LRG) samples of SDSS-I/II. The remaining 10% of galaxies above this cut have a
late-type morphology and may be analogous to the "passive spirals" found at
lower redshift. We find that 23+/-4% of the early-type galaxies are unresolved
multiple systems in the SDSS imaging. We estimate that at least 50% of these
are real associations (not projection effects) and may represent a significant
"dry merger" fraction. We study the SDSS pipeline sizes of BOSS galaxies which
we find to be systematically larger (by 40%) than those measured from HST
images, and provide a statistical correction for the difference. These details
of the BOSS galaxies will help users of the data fine-tune their selection
criteria, dependent on their science applications. For example, the main goal
of BOSS is to measure the cosmic distance scale and expansion rate of the
Universe to percent-level precision - a point where systematic effects due to
the details of target selection may become important.Comment: 18 pages, 11 figures; v2 as accepted by MNRA
A quantum Monte Carlo study of the one-dimensional ionic Hubbard model
Quantum Monte Carlo methods are used to study a quantum phase transition in a
1D Hubbard model with a staggered ionic potential (D). Using recently
formulated methods, the electronic polarization and localization are determined
directly from the correlated ground state wavefunction and compared to results
of previous work using exact diagonalization and Hartree-Fock. We find that the
model undergoes a thermodynamic transition from a band insulator (BI) to a
broken-symmetry bond ordered (BO) phase as the ratio of U/D is increased. Since
it is known that at D = 0 the usual Hubbard model is a Mott insulator (MI) with
no long-range order, we have searched for a second transition to this state by
(i) increasing U at fixed ionic potential (D) and (ii) decreasing D at fixed U.
We find no transition from the BO to MI state, and we propose that the MI state
in 1D is unstable to bond ordering under the addition of any finite ionic
potential. In real 1D systems the symmetric MI phase is never stable and the
transition is from a symmetric BI phase to a dimerized BO phase, with a
metallic point at the transition
Measuring model variability using robust non-parametric testing
Training a deep neural network often involves stochastic optimization,
meaning each run will produce a different model. The seed used to initialize
random elements of the optimization procedure heavily influences the quality of
a trained model, which may be obscure from many commonly reported summary
statistics, like accuracy. However, random seed is often not included in
hyper-parameter optimization, perhaps because the relationship between seed and
model quality is hard to describe. This work attempts to describe the
relationship between deep net models trained with different random seeds and
the behavior of the expected model. We adopt robust hypothesis testing to
propose a novel summary statistic for network similarity, referred to as the
-trimming level. We use the -trimming level to show that the
empirical cumulative distribution function of an ensemble model created from a
collection of trained models with different random seeds approximates the
average of these functions as the number of models in the collection grows
large. This insight provides guidance for how many random seeds should be
sampled to ensure that an ensemble of these trained models is a reliable
representative. We also show that the -trimming level is more
expressive than different performance metrics like validation accuracy, churn,
or expected calibration error when taken alone and may help with random seed
selection in a more principled fashion. We demonstrate the value of the
proposed statistic in real experiments and illustrate the advantage of
fine-tuning over random seed with an experiment in transfer learning
Legal Terms of Use and Public Genealogy Websites
Public genealogy websites, to which individuals upload family history, genealogy, and sometimes individual genetic data, have been used in an increasing number of public health, epidemiological, and genetic studies. Yet there is little awareness among researchers of the legal rules that govern the use of these online resources. We analyzed the online Terms of Use (TOU) applicable to 17 popular genealogy websites and found that none of them expressly permit scientific research, while at least 13 contain restrictions that may limit or prohibit scientific research using data obtained from those sites. In order to ensure that researchers who use genealogy and other data from these sites for public health and other scientific research purposes do not inadvertently breach applicable TOUs, we recommend that genealogy website operators consider revising their TOUs to permit this activity
A Probabilistic Model for Aircraft in Climb using Monotonic Functional Gaussian Process Emulators
Ensuring vertical separation is a key means of maintaining safe separation
between aircraft in congested airspace. Aircraft trajectories are modelled in
the presence of significant epistemic uncertainty, leading to discrepancies
between observed trajectories and the predictions of deterministic models,
hampering the task of planning to ensure safe separation. In this paper a
probabilistic model is presented, for the purpose of emulating the trajectories
of aircraft in climb and bounding the uncertainty of the predicted trajectory.
A monotonic, functional representation exploits the spatio-temporal
correlations in the radar observations. Through the use of Gaussian Process
Emulators, features that parameterise the climb are mapped directly to
functional outputs, providing a fast approximation, while ensuring that the
resulting trajectory is monotonic. The model was applied as a probabilistic
digital twin for aircraft in climb and baselined against BADA, a deterministic
model widely used in industry. When applied to an unseen test dataset, the
probabilistic model was found to provide a mean prediction that was 21% more
accurate, with a 34% sharper forecast
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Multiple Independent Loci at Chromosome 15q25.1 Affect Smoking Quantity: a Meta-Analysis and Comparison with Lung Cancer and COPD
Recently, genetic association findings for nicotine dependence, smoking behavior, and smoking-related diseases converged to implicate the chromosome 15q25.1 region, which includes the CHRNA5-CHRNA3-CHRNB4 cholinergic nicotinic receptor subunit genes. In particular, association with the nonsynonymous CHRNA5 SNP rs16969968 and correlates has been replicated in several independent studies. Extensive genotyping of this region has suggested additional statistically distinct signals for nicotine dependence, tagged by rs578776 and rs588765. One goal of the Consortium for the Genetic Analysis of Smoking Phenotypes (CGASP) is to elucidate the associations among these markers and dichotomous smoking quantity (heavy versus light smoking), lung cancer, and chronic obstructive pulmonary disease (COPD). We performed a meta-analysis across 34 datasets of European-ancestry subjects, including 38,617 smokers who were assessed for cigarettes-per-day, 7,700 lung cancer cases and 5,914 lung-cancer-free controls (all smokers), and 2,614 COPD cases and 3,568 COPD-free controls (all smokers). We demonstrate statistically independent associations of rs16969968 and rs588765 with smoking (mutually adjusted p-values<10 and <10 respectively). Because the risk alleles at these loci are negatively correlated, their association with smoking is stronger in the joint model than when each SNP is analyzed alone. Rs578776 also demonstrates association with smoking after adjustment for rs16969968 (p<10). In models adjusting for cigarettes-per-day, we confirm the association between rs16969968 and lung cancer (p<10) and observe a nominally significant association with COPD (p = 0.01); the other loci are not significantly associated with either lung cancer or COPD after adjusting for rs16969968. This study provides strong evidence that multiple statistically distinct loci in this region affect smoking behavior. This study is also the first report of association between rs588765 (and correlates) and smoking that achieves genome-wide significance; these SNPs have previously been associated with mRNA levels of CHRNA5 in brain and lung tissue
Leap into... Student-centred learning
Part of a collection of documents from Leap, formerly a University of Adelaide website providing information about learning and teaching initiatives at the University, archived in PDF format 26th April 2012.This publication is designed for University of Adelaide staff who are interested in student-centred learning—what it is and how it can be put into practice to enhance learning and teaching. We've tried to create a picture of student-centred learning that is broad and general enough to be useful to teachers in many, if not all disciplines, and with an eye to the variety of teaching settings, from the lab to the large lecture theatre to the studio and more.Christine Ingleton, Margaret Kiley, Robert Cannon and Tim Rogers for the University of Adelaide ACU
Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans
Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have
fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in
25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16
regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of
correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP,
while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in
Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium
(LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region.
Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant
enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the
refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa,
an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of
PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent
signals within the same regio
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