Modelling the dynamics of intramammary E. coli infections in dairy cows: understanding mechanisms that distinguish transient from persistent infections

The majority of intramammary infections with Escherichia coli in dairy cows result in transient infections with duration of about 10 days or less, although more persistent infections (2 months or longer) have been identified. We apply a mathematical model to explore the role of an intracellular mammary epithelial cell reservoir in the dynamics of infection. We included biological knowledge of the bovine immune response and known characteristics of the bacterial population in both transient and persistent infections. The results indicate that varying the survival duration of the intracellular reservoir reproduces the data for both transient and persistent infections. Survival in an intracellular reservoir is the most likely mechanism that ensures persistence of E. coli infections in mammary glands. Knowledge of the pathogenesis of persistent infections is essential to develop preventive and treatment programmes for these important infections in dairy cows

Validity of the WKB Approximation in Calculating the Asymptotic Quasinormal Modes of Black Holes

In this paper, we categorize non-rotating black hole spacetimes based on their pole structure and in each of these categories we determine whether the WKB approximation is a valid approximation for calculating the asymptotic quasinormal modes. We show that Schwarzschild black holes with the Gauss-Bonnet correction belong to the category in which the WKB approximation is invalid for calculating these modes. In this context, we further discuss and clarify some of the ambiguity in the literature surrounding the validity conditions provided for the WKB approximation.Comment: 10 page

Assessing neural tuning for object perception in schizophrenia and bipolar disorder with multivariate pattern analysis of fMRI data.

IntroductionDeficits in visual perception are well-established in schizophrenia and are linked to abnormal activity in the lateral occipital complex (LOC). Related deficits may exist in bipolar disorder. LOC contains neurons tuned to object features. It is unknown whether neural tuning in LOC or other visual areas is abnormal in patients, contributing to abnormal perception during visual tasks. This study used multivariate pattern analysis (MVPA) to investigate perceptual tuning for objects in schizophrenia and bipolar disorder.MethodsFifty schizophrenia participants, 51 bipolar disorder participants, and 47 matched healthy controls completed five functional magnetic resonance imaging (fMRI) runs of a perceptual task in which they viewed pictures of four different objects and an outdoor scene. We performed classification analyses designed to assess the distinctiveness of activity corresponding to perception of each stimulus in LOC (a functionally localized region of interest). We also performed similar classification analyses throughout the brain using a searchlight technique. We compared classification accuracy and patterns of classification errors across groups.ResultsStimulus classification accuracy was significantly above chance in all groups in LOC and throughout visual cortex. Classification errors were mostly within-category confusions (e.g., misclassifying one chair as another chair). There were no group differences in classification accuracy or patterns of confusion.ConclusionsThe results show for the first time MVPA can be used successfully to classify individual perceptual stimuli in schizophrenia and bipolar disorder. However, the results do not provide evidence of abnormal neural tuning in schizophrenia and bipolar disorder

Вивчення кварк-глюонної плазми хіггсового механізму порушення електрослабкої симетрії

Вже багато років наукове оточення всього світу хвилює питання звідки бере свій початок стандартна теорія походження матерії

Submillimeter Observations of the Ultraluminous BAL Quasar APM 08279+5255

With an inferred bolometric luminosity of 5\times10^{15}{\rm \lsun}, the recently identified z=3.87, broad absorption line quasar APM 08279+5255 is apparently the most luminous object currently known. As half of its prodigious emission occurs in the infrared, APM 08279+5255 also represents the most extreme example of an Ultraluminous Infrared Galaxy. Here, we present new submillimeter observations of this phenomenal object; while indicating that a vast quantity of dust is present, these data prove to be incompatible with current models of emission mechanisms and reprocessing in ultraluminous systems. The influence of gravitational lensing upon these models is considered and we find that while the emission from the central continuum emitting region may be significantly enhanced, lensing induced magnification cannot easily reconcile the models with observations. We conclude that further modeling, including the effects of any differential magnification is required to explain the observed emission from APM 08279+5255.Comment: 12 Pages with Two figures. Accepted for publication in the Astrophysical Journal Letter

Impurity spin relaxation in S=1/2 XX chains

Dynamic autocorrelations $$ (\alpha=x,z) of an isolated impurity spin in a S=1/2 XX chain are calculated. The impurity spin, defined by a local change in the nearest-neighbor coupling, is either in the bulk or at the boundary of the open-ended chain. The exact numerical calculation of the correlations employs the Jordan-Wigner mapping from spin operators to Fermi operators; effects of finite system size can be eliminated. Two distinct temperature regimes are observed in the long-time asymptotic behavior. At T=0 only power laws are present. At high T the x correlation decays exponentially (except at short times) while the z correlation still shows an asymptotic power law (different from the one at T=0) after an intermediate exponential phase. The boundary impurity correlations follow power laws at all T. The power laws for the z correlation and the boundary correlations can be deduced from the impurity-induced changes in the properties of the Jordan-Wigner fermion states.Comment: Final version to be published in Phys. Rev. B. Three references added, extended discussion of relation to previous wor

Heterotic/type I duality, D-instantons and an N=2 AdS/CFT correspondence

D-instanton effects are studied for the IIB orientifold T^2/I\Omega(-1)^{F_L} of Sen using type I/heterotic duality. An exact one loop threshold calculation of t_8 \tr F^4 and t_8(\tr F^2)^2 terms for the heterotic string on T^2 with Wilson lines breaking SO(32) to SO(8)^4 is related to D-instanton induced terms in the worldvolume of D7 branes in the orientifold. Introducing D3 branes and using the AdS/CFT correspondence in this case, these terms are used to calculate Yang-Mills instanton contributions to four point functions of the large N_c limit of N=2 USp(2N_c) SYM with four fundamental and one antisymmetric tensor hypermultiplets.Comment: 25 pages, harvmac(b), one figure, v2: minor changes, version to appear in PR