4,063 research outputs found
Necrotizing Infiltrative Lipomatosis in a Miniature Zebu Bull (Bos primigenius indicus)
Lipomatosis is described in a miniature Zebu, Bos primigenius indicus, bull that died of perianesthetic complications. This is the first pathologic description of lipomatosis that we are aware of in this species and breed of cattle. Infiltration of multiple visceral organs is described and depicted along with comparison to previously published cases of lipomatosis in other breeds of cattle
Universality in the merging dynamics of parametric active contours: a study in MRI-based lung segmentation
Measurement of lung ventilation is one of the most reliable techniques of
diagnosing pulmonary diseases. The time consuming and bias prone traditional
methods using hyperpolarized HHe and H magnetic resonance
imageries have recently been improved by an automated technique based on
multiple active contour evolution. Mapping results from an equivalent
thermodynamic model, here we analyse the fundamental dynamics orchestrating the
active contour (AC) method. We show that the numerical method is inherently
connected to the universal scaling behavior of a classical nucleation-like
dynamics. The favorable comparison of the exponent values with the theoretical
model render further credentials to our claim.Comment: 4 pages, 4 figure
Expression, Purification, Crystallization and Preliminary X-ray Studies of Histamine Dehydroganase from Nocardioides simplex
This is the publisher's version, also available electronically from http://scripts.iucr.org/cgi-bin/paper?S1744309108023336.Histamine dehydrogenase (HADH) from Nocardioides simplex catalyzes the oxidative deamination of histamine to produce imidazole acetaldehyde and an ammonium ion. HADH is functionally related to trimethylamine dehydrogenase (TMADH), but HADH has strict substrate specificity towards histamine. HADH is a homodimer, with each 76 kDa subunit containing two redox cofactors: a [4Fe-4S] cluster and an unusual covalently bound flavin mononucleotide, 6-S-cysteinyl-FMN. In order to understand the substrate specificity of HADH, it was sought to determine its structure by X-ray crystallography. This enzyme has been expressed recombinantly in Escherichia coli and successfully crystallized in two forms. Diffraction data were collected to 2.7 Å resolution at the SSRL synchrotron with 99.7% completeness. The crystals belonged to the orthorhombic space group P212121, with unit-cell parameters a = 101.14, b = 107.03, c = 153.35 Å
Spiders fluoresce variably across many taxa
The evolution of fluorescence is largely unexplored, despite the newfound occurrence of this phenomenon in a variety of organisms. We document that spiders fluoresce under ultraviolet illumination, and find that the expression of this trait varies greatly among taxa in this species-rich group. All spiders we examined possess fluorophores in their haemolymph, but bright fluorescence appears to result when a spider sequesters fluorophores in its setae or cuticle. By sampling widely across spider taxa, we determine that fluorescent expression is labile and has evolved multiple times. Moreover, examination of the excitation and emission properties of extracted fluorophores reveals that spiders possess multiple fluorophores and that these differ among some families, indicating that novel fluorophores have evolved during spider diversification. Because many spiders fluoresce in wavelengths visible to their predators and prey (birds and insects), we propose that natural selection imposed by predator–prey interactions may drive the evolution of fluorescence in spiders
Community Engagement with Older Adults to Evaluate Interprofessional Education in Allied Healthcare Students
Purpose: To examine students’ perceptions of interprofessional education (IPE) as a result of their participation in a community engagement experience with older adults. Methods: Thirty-six students enrolled in the undergraduate majors of athletic training, exercise science, and nutrition participated in an 8-week fall prevention program in two community dwelling senior centers. A one-group pretest-posttest evaluation design was used to assess the IPE experience of the students. Students completed the University of the West England Interprofessional Questionnaire pre and post intervention. Results: Both pretest and posttest student self-assessments of communication and teamwork skills ranged from slightly positive to neutral (means from 2.0 to 2.6). Students reported a statistical change in attitude from neutral (M = 2.3, SD + 1.1) in the direction of slightly positive (M = 2.0, SD + 1.1) toward being able to become quickly involved in new teams/groups from pretest to posttest t (26) = 2.53, p = .018; d = 0.49. 95% of students strongly agreed or agreed that the experience enabled them to interact with an unfamiliar and unique population as well as increased their understanding of other allied healthcare disciplines as a result of participation. No individual items nor the summary score exhibited statistical improvements over time. Conclusion: Overall, the intervention was successful in describing the IPE positive experiences and attitudes of undergraduate allied healthcare students when working in a senior adult population
TransNets: Learning to Transform for Recommendation
Recently, deep learning methods have been shown to improve the performance of
recommender systems over traditional methods, especially when review text is
available. For example, a recent model, DeepCoNN, uses neural nets to learn one
latent representation for the text of all reviews written by a target user, and
a second latent representation for the text of all reviews for a target item,
and then combines these latent representations to obtain state-of-the-art
performance on recommendation tasks. We show that (unsurprisingly) much of the
predictive value of review text comes from reviews of the target user for the
target item. We then introduce a way in which this information can be used in
recommendation, even when the target user's review for the target item is not
available. Our model, called TransNets, extends the DeepCoNN model by
introducing an additional latent layer representing the target user-target item
pair. We then regularize this layer, at training time, to be similar to another
latent representation of the target user's review of the target item. We show
that TransNets and extensions of it improve substantially over the previous
state-of-the-art.Comment: Accepted for publication in the 11th ACM Conference on Recommender
Systems (RecSys 2017
Modeling Adaptive Regulatory T-Cell Dynamics during Early HIV Infection
Regulatory T-cells (Tregs) are a subset of CD4+ T-cells that have been found to suppress the immune response. During HIV viral infection, Treg activity has been observed to have both beneficial and deleterious effects on patient recovery; however, the extent to which this is regulated is poorly understood. We hypothesize that this dichotomy in behavior is attributed to Treg dynamics changing over the course of infection through the proliferation of an ‘adaptive’ Treg population which targets HIV-specific immune responses. To investigate the role Tregs play in HIV infection, a delay differatial equation model was constructed to examine (1) the possible existence of two distinct Treg populations, normal (nTregs) and adaptive (aTregs), and (2) their respective effects in limiting viral load. Sensitivity analysis was performed to test parameter regimes that show the proportionality of viral load with adaptive regulatory populations and also gave insight into the importance of downregulation of CD4+ cells by normal Tregs on viral loads. Through the inclusion of Treg populations in the model, a diverse array of viral dynamics was found. Specifically, oscillatory and steady state behaviors were both witnessed and it was seen that the model provided a more accurate depiction of the effector cell population as compared with previous models. Through further studies of adaptive and normal Tregs, improved treatments for HIV can be constructed for patients and the viral mechanisms of infection can be further elucidated
Time to Evolve? Potential Evolutionary Responses of Fraser River Sockeye Salmon to Climate Change and Effects on Persistence
Evolutionary adaptation affects demographic resilience to climate change but few studies have attempted to project changes in selective pressures or quantify impacts of trait responses on population dynamics and extinction risk. We used a novel individual-based model to explore potential evolutionary changes in migration timing and the consequences for population persistence in sockeye salmon Oncorhynchus nerka in the Fraser River, Canada, under scenarios of future climate warming. Adult sockeye salmon are highly sensitive to increases in water temperature during their arduous upriver migration, raising concerns about the fate of these ecologically, culturally, and commercially important fish in a warmer future. Our results suggest that evolution of upriver migration timing could allow these salmon to avoid increasingly frequent stressful temperatures, with the odds of population persistence increasing in proportion to the trait heritability and phenotypic variance. With a simulated 2°C increase in average summer river temperatures by 2100, adult migration timing from the ocean to the river advanced by ∼10 days when the heritability was 0.5, while the risk of quasi-extinction was only 17% of that faced by populations with zero evolutionary potential (i.e., heritability fixed at zero). The rates of evolution required to maintain persistence under simulated scenarios of moderate to rapid warming are plausible based on estimated heritabilities and rates of microevolution of timing traits in salmon and related species, although further empirical work is required to assess potential genetic and ecophysiological constraints on phenological adaptation. These results highlight the benefits to salmon management of maintaining evolutionary potential within populations, in addition to conserving key habitats and minimizing additional stressors where possible, as a means to build resilience to ongoing climate change. More generally, they demonstrate the importance and feasibility of considering evolutionary processes, in addition to ecology and demography, when projecting population responses to environmental change
The singular continuous diffraction measure of the Thue-Morse chain
The paradigm for singular continuous spectra in symbolic dynamics and in
mathematical diffraction is provided by the Thue-Morse chain, in its
realisation as a binary sequence with values in . We revisit this
example and derive a functional equation together with an explicit form of the
corresponding singular continuous diffraction measure, which is related to the
known representation as a Riesz product.Comment: 6 pages, 1 figure; revised and improved versio
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