2,711 research outputs found
Comparing Permeability of Matrix Cover Types for the Marsh Rice Rat (Oryzomys palustris)
Context Matrix land cover types differ in permeability to animals moving between habitat patches, and animals may actually move faster across lesssuitable areas. Marsh rice rats are wetland specialists whose dispersal crosses upland matrix. Objectives Our objectives were to (1) compare matrix permeability for the marsh rice rat among upland cover types, (2) compare permeability within versus outside perceptual range of the wetland, and (3) explore intrinsic and extrinsic features influencing matrix use and permeability. Methods We quantified permeability of grassland, crop field, and forest to the marsh rice rat during 2011–2012, by marking rats in wetlands and estimating the slope of capture rate versus distance (0–95 m) into the matrix. We also compared permeability within (0–15 m) and beyond the perceptual range of rice rats, and tested whether age, sex, time, water depth, rice rat abundance, and vegetation density influenced matrix use and permeability. Results Permeability was greater for soybean fields than grassland or forest but did not appear to differ within versus beyond rice rats’ perceptual range. Matrix capture rates were higher early in the study and in times and locations with thick ground vegetation and high rice rat abundance in the wetlands. Rice rats captured in the matrix were younger than those in wetland patches. Conclusions Our findings expand known matrix use by marsh rice rats, and support permeability being high in matrix types dissimilar to suitable habitat. Studying individual movements will help identify mechanisms underlying enhanced permeability in crop fields
Human long intrinsically disordered protein regions are frequent targets of positive selection
Intrinsically disordered regions occur frequently in proteins and are characterized by a lack of a well-defined three-dimensional structure. Although these regions do not show a higher-order of structural organization, they are known to be functionally important. Disordered regions are rapidly evolving, largely attributed to relaxed purifying selection and an increased role of genetic drift. It has also been suggested that positive selection might contribute to their rapid diversification. However, for our own species it is currently unknown whether positive selection has played a role during the evolution of these protein regions. Here we address this question by investigating the evolutionary pattern of more than 6,600 human proteins with intrinsically disordered regions and their ordered counterparts. Our comparative approach with data from more than 90 mammalian genomes uses a-priori knowledge of disordered protein regions and we show that this increases the power to detect positive selection by an order of magnitude. We can confirm that human intrinsically disordered regions evolve more rapidly, not only within humans but also across the entire mammalian phylogeny. They have, however, experienced substantial evolutionary constraint, hinting at their fundamental functional importance. We find compelling evidence that disordered protein regions are frequent targets of positive selection and estimate that the relative rate of adaptive substitutions differs 4-fold between disordered and ordered protein regions in humans. Our results suggest that disordered protein regions are important targets of genetic innovation and that the contribution of positive selection in these regions is more pronounced than in other protein parts
Proton lifetime bounds from chirally symmetric lattice QCD
We present results for the matrix elements relevant for proton decay in Grand
Unified Theories (GUTs). The calculation is performed at a fixed lattice
spacing a^{-1}=1.73(3) GeV using 2+1 flavors of domain wall fermions on
lattices of size 16^3\times32 and 24^3\times64 with a fifth dimension of length
16. We use the indirect method which relies on an effective field theory
description of proton decay, where we need to estimate the low energy
constants, \alpha = -0.0112(25) GeV^3 and \beta = 0.0120(26) GeV^3. We relate
these low energy constants to the proton decay matrix elements using leading
order chiral perturbation theory. These can then be combined with experimental
bounds on the proton lifetime to bound parameters of individual GUTs.Comment: 17 pages, 9 Figure
Origin Gaps and the Eternal Sunshine of the Second-Order Pendulum
The rich experiences of an intentional, goal-oriented life emerge, in an
unpredictable fashion, from the basic laws of physics. Here I argue that this
unpredictability is no mirage: there are true gaps between life and non-life,
mind and mindlessness, and even between functional societies and groups of
Hobbesian individuals. These gaps, I suggest, emerge from the mathematics of
self-reference, and the logical barriers to prediction that self-referring
systems present. Still, a mathematical truth does not imply a physical one: the
universe need not have made self-reference possible. It did, and the question
then is how. In the second half of this essay, I show how a basic move in
physics, known as renormalization, transforms the "forgetful" second-order
equations of fundamental physics into a rich, self-referential world that makes
possible the major transitions we care so much about. While the universe runs
in assembly code, the coarse-grained version runs in LISP, and it is from that
the world of aim and intention grows.Comment: FQXI Prize Essay 2017. 18 pages, including afterword on
Ostrogradsky's Theorem and an exchange with John Bova, Dresden Craig, and
Paul Livingsto
Antibacterial Properties of a Tri-Sodium Citrate Modified Glass Polyalkenoate Cement
Primary deep infection following joint replacement surgery accounts for 7% of all revisions. Glass polyalkenoate cements (GPCs) have previously been shown to exhibit antibacterial properties. The present study had two objectives. The first was to determine if addition of tri-sodium citrate (TSC) to the powder phase of an Al-free GPC (0.04 SrO-0.12 CaO-0.36 ZnO-0.48 SiO2, by mole fraction) enhanced the resultant cement\u27s antibacterial properties against three strains of bacteria that are commonly found in periprosthetic sites following total joint replacements (TJRs); namely, E. coli, B. fragilis, and S. epidermidis. Four cement sets were prepared, which contained 0 wt% TSC (control), 5 wt% TSC, 10 wt% TSC, and 15 wt% TSC. All the TSC-modified cements were found to exhibit large inhibition zones against all the bacterial strains, especially the cement containing 15 wt% TSC against E. coli. The antibacterial properties of the TSC containing GPCs are attributed to the release of Zn and Na ions from the cements and the presence of the TSC. The second objective was to investigate if, when a modified GPC is embedded in a bovine bone model, ionic transfer occurs. It was found that Zn ions migrated from the cement to the surrounding bone, particularly at the cement-bone interface. This is a desirable outcome as Zn ions are known to play a vital role in both bone metabolism and the regeneration of healthy bone. The present results point to the potential clinical benefits of using TSC-modified GPCs in TJRs. © 2009 Wiley Periodicals, Inc
Mentalising skills in generic mental healthcare settings: can we make our day-to-day interactions more therapeutic?
Aims and method: Caring for patients with personality disorder is one of the biggest challenges in psychiatric work. We investigated whether mentalisation-based treatment skills (MBT-S) teaching improves clinicians' understanding of mentalising and attitudes towards personality disorder. Self-report questionnaires (Knowledge and Application of MBT (KAMQ) and Attitudes to Personality Disorder (APDQ)) were completed at baseline and after a 2-day MBT-S workshop.
Results: Ninety-two healthcare professionals completed questionnaires before and after training. The mean within-participant increase in scores from baseline to end-of-programme was 11.6 points (95% CI 10.0-13.3) for the KAMQ and 4.0 points (1.8-6.2) for the APDQ.
Clinical implications: MBT-S is a short intervention that is effective in improving clinicians' knowledge of personality disorder and mentalisation. That attitudes to personality disorder improved overall is encouraging in relation to the possibility of deeper learning in staff and, ultimately, improved care for patients with personality disorder.
Declaration of interest: None
A simple algorithm for quantifying DNA methylation levels on multiple independent CpG sites in bisulfite genomic sequencing electropherograms
DNA methylation at cytosines is a widely studied epigenetic modification. Methylation is commonly detected using bisulfite modification of DNA followed by PCR and additional techniques such as restriction digestion or sequencing. These additional techniques are either laborious, require specialized equipment, or are not quantitative. Here we describe a simple algorithm that yields quantitative results from analysis of conventional four-dye-trace sequencing. We call this method Mquant and we compare it with the established laboratory method of combined bisulfite restriction assay (COBRA). This analysis of sequencing electropherograms provides a simple, easily applied method to quantify DNA methylation at specific CpG sites
A polymorphism in the interleukin-4 receptor affects the ability of interleukin-4 to regulate Th17 cells: a possible immunoregulatory mechanism for genetic control of the severity of rheumatoid arthritis
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94408/1/Wallis_2011_Polymorphism_interleukin-4_receptor.pdf165
The signature of competition in ecomorphological traits across the avian radiation
Competition for shared resources represents a fundamental driver of biological diversity. However, the tempo and mode of phenotypic evolution in deep-time has been predominantly investigated using trait evolutionary models which assume that lineages evolve independently from each other. Consequently, the role of species interactions in driving macroevolutionary dynamics remains poorly understood. Here, we quantify the prevalence for signatures of competition between related species in the evolution of ecomorphological traits across the bird radiation. We find that mechanistic trait models accounting for the effect of species interactions on phenotypic divergence provide the best fit for the data on at least one trait axis in 27 out of 59 clades ranging between 21 and 195 species. Where it occurs, the signature of competition generally coincides with positive species diversity-dependence, driven by the accumulation of lineages with similar ecologies, and we find scarce evidence for trait-dependent or negative diversity-dependent phenotypic evolution. Overall, our results suggest that the footprint of interspecific competition is often eroded in long-term patterns of phenotypic diversification, and that other selection pressures may predominantly shape ecomorphological diversity among extant species at macroevolutionary scales
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