16,526 research outputs found

    Evolution of the Fern Family Osmundaceae Based on Anatomical Studies

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    105-169http://deepblue.lib.umich.edu/bitstream/2027.42/48450/2/ID299.pd

    Evolution of the Fern Genus Osmunda

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    139-203http://deepblue.lib.umich.edu/bitstream/2027.42/48413/2/ID260.pd

    Silicified Cones and Vegetative Remains of Pinus from Eocene of British Columbia

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    101-118http://deepblue.lib.umich.edu/bitstream/2027.42/48477/2/ID327.pd

    Exploration of the faecal microbiota and biomarker discovery in equine grass sickness

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    Equine grass sickness (EGS) is a frequently fatal disease of horses, responsible for the death of 1-2% of the UK horse population annually. The etiology of this disease is currently uncharacterized although there is evidence it is associated with Clostridium botulinum neurotoxin in the gut. Prevention is currently not possible and ileal biopsy diagnosis is invasive. The aim of this study was to characterize the fecal microbiota and biofluid metabolic profiles of EGS horses, to further understand the mechanisms underlying this disease and identify metabolic biomarkers to aid in diagnosis. Urine, plasma and feces were collected from horses with EGS, matched controls (MC), and hospital controls (HC). Sequencing the16S rRNA gene of the fecal bacterial population of the study horses found a severe dysbiosis in EGS horses, with an increase in Bacteroidetes and a decrease in Firmicutes bacteria. Metabolic profiling by 1H nuclear magnetic resonance (NMR) spectroscopy found EGS to be associated with the lower urinary excretion of hippurate and 4-cresyl sulfate and higher excretion of O-acetyl carnitine and trimethylamine-N-oxide (TMAO). The predictive ability of the complete urinary metabolic signature and using the four discriminatory urinary metabolites to classify horses by disease status was assessed using a second (test) set of horses. The urinary metabolome and a combination of the four candidate biomarkers showed promise in aiding the identification of horses with EGS. Characterization of the metabolic shifts associated with EGS offers the potential of a non-invasive test to aid pre-mortem diagnosis

    Quasi-equilibria in one-dimensional self-gravitating many body systems

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    The microscopic dynamics of one-dimensional self-gravitating many-body systems is studied. We examine two courses of the evolution which has the isothermal and stationary water-bag distribution as initial conditions. We investigate the evolution of the systems toward thermal equilibrium. It is found that when the number of degrees of freedom of the system is increased, the water-bag distribution becomes a quasi-equilibrium, and also the stochasticity of the system reduces. This results suggest that the phase space of the system is effectively not ergodic and the system with large degreees of freedom approaches to the near-integrable one.Comment: 21pages + 7 figures (available upon request), revtex, submitted to Physical Review

    Cross Section Measurements Using the Zero Degree Detector

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    The Zero Degree Detector (ZDD) is an instrument that has been used in accelerator exposures to measure the angular dependence of particles produced in heavy ion fragmentation experiments. The ZDD uses two identical layers of pixelated silicon detectors that make coincident measurements over the active area of the instrument. The angular distribution of secondary particle produced in nuclear interactions for several heavy ions: and target materials will be presented along with performance characteristic of the instrument

    Analytic regularity for a singularly perturbed system of reaction-diffusion equations with multiple scales: proofs

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    We consider a coupled system of two singularly perturbed reaction-diffusion equations, with two small parameters 0<ϵμ10< \epsilon \le \mu \le 1, each multiplying the highest derivative in the equations. The presence of these parameters causes the solution(s) to have \emph{boundary layers} which overlap and interact, based on the relative size of ϵ\epsilon and % \mu. We construct full asymptotic expansions together with error bounds that cover the complete range 0<ϵμ10 < \epsilon \leq \mu \leq 1. For the present case of analytic input data, we derive derivative growth estimates for the terms of the asymptotic expansion that are explicit in the perturbation parameters and the expansion order

    On separable Fokker-Planck equations with a constant diagonal diffusion matrix

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    We classify (1+3)-dimensional Fokker-Planck equations with a constant diagonal diffusion matrix that are solvable by the method of separation of variables. As a result, we get possible forms of the drift coefficients B1(x),B2(x),B3(x)B_1(\vec x),B_2(\vec x),B_3(\vec x) providing separability of the corresponding Fokker-Planck equations and carry out variable separation in the latter. It is established, in particular, that the necessary condition for the Fokker-Planck equation to be separable is that the drift coefficients B(x)\vec B(\vec x) must be linear. We also find the necessary condition for R-separability of the Fokker-Planck equation. Furthermore, exact solutions of the Fokker-Planck equation with separated variables are constructedComment: 20 pages, LaTe

    Reliable microsatellite genotyping of the Eurasian badger (Meles meles) using faecal DNA

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    The potential link between badgers and bovine tuberculosis has made it vital to develop accurate techniques to census badgers. Here we investigate the potential of using genetic profiles obtained from faecal DNA as a basis for population size estimation. After trialling several methods we obtained a high amplification success rate (89%) by storing faeces in 70% ethanol and using the guanidine thiocyanate/silica method for extraction. Using 70% ethanol as a storage agent had the advantage of it being an antiseptic. In order to obtain reliable genotypes with fewer amplification reactions than the standard multiple-tubes approach, we devised a comparative approach in which genetic profiles were compared and replication directed at similar, but not identical, genotypes. This modified method achieved a reduction in polymerase chain reactions comparable with the maximumlikelihood model when just using reliability criteria, and was slightly better when using reliability criteria with the additional proviso that alleles must be observed twice to be considered reliable. Our comparative approach would be best suited for studies that include multiple faeces from each individual. We utilized our approach in a well-studied population of badgers from which individuals had been sampled and reliable genotypes obtained. In a study of 53 faeces sampled from three social groups over 10 days, we found that direct enumeration could not be used to estimate population size, but that the application of mark–recapture models has the potential to provide more accurate results
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