A simplified structure for the second order cosmological perturbation equations

Increasingly accurate observations of the cosmic microwave background and the large scale distribution of galaxies necessitate the study of nonlinear perturbations of Friedmann-Lemaitre cosmologies, whose equations are notoriously complicated. In this paper we present a new derivation of the governing equations for second order perturbations within the framework of the metric-based approach that is minimal, as regards amount of calculation and length of expressions, and flexible, as regards choice of gauge and stress-energy tensor. Because of their generality and the simplicity of their structure our equations provide a convenient starting point for determining the behaviour of nonlinear perturbations of FL cosmologies with any given stress-energy content, using either the Poisson gauge or the uniform curvature gauge.Comment: 30 pages, no figures. Changed title to the one in published version and some minor changes and addition

Phase Diagram of the Holstein-Hubbard Two-Leg Ladder

Using a functional renormalization group method, we obtain the phase diagram of the two-leg ladder system within the Holstein-Hubbard model, which includes both electron-electron and electron-phonon interactions. Our renormalization group technique allows us to analyze the problem for both weak and strong electron-phonon coupling. We show that, in contrast results from conventional weak coupling studies, electron-phonon interactions can dominate electron-electron interactions because of retardation effects.Comment: 4 page

Performance on a pattern separation task by Alzheimer's patients shows possible links between disrupted dentate gyrus activity and apolipoprotein E ∈4 status and cerebrospinal fluid amyloid-β42 levels

This is the final version of the article. Available from the publisher via the DOI in this record.INTRODUCTION: Emerging evidence suggests that decreased adult hippocampal neurogenesis represents an early critical event in the course of Alzheimer's disease (AD). In mice, adult neurogenesis is reduced by knock-in alleles for human apolipoprotein E (ApoE) ∈4. Decreased dentate gyrus (DG) neural progenitor cells proliferation has been observed in the triple-transgenic mouse model of AD (3xTg-AD); this reduction being directly associated with the presence of amyloid-β (Aβ) plaques and an increase in the number of Aβ-containing neurons in the hippocampus. Cognitive tasks involving difficult pattern separations have been shown to reflect DG activity and thus potentially neurogenesis in both animals and man. This study involved the administration of a pattern separation paradigm to Alzheimer's patients to investigate relationships between task performance and both ApoE status and cerebrospinal fluid (CSF) Aβ42 levels. METHODS: The CDR System pattern separation task involves the presentation of pictures that must later be discriminated from closely similar pictures. This paper presents pattern separation data from 66 mild to moderate AD patients, of which 50 were genotyped and 65 in whom CSF Aβ42 was measured. RESULTS: ApoE ∈4 homozygotes were not compromised on the easy pattern separations compared with the other patients, but they were statistically significantly poorer at the difficult separations. In all patients CSF Aβ42 correlated significantly with the ability to make the difficult discriminations, but not easier discriminations. Pattern separation speed correlated negatively with CSF Aβ42, and thus the association was not due to increased impulsivity. CONCLUSIONS: These are, to our knowledge, the first human pattern separation data to suggest a possible genetic link to poor hippocampal neurogenesis in AD, as well as a relationship to Aβ42. Therapies which target neurogenesis may thus be useful in preventing the early stages of AD, notably in ApoE ∈4 homocygotes.This study was financially supported by AstraZeneca, Sweden

Pneumatose kystique iléale révélée par un volvulus du grêle

La pneumatose kystique intestinale est une pathologie rare qui se caractérise par la présence de kystes gazeux dans la paroi intestinale. Elle est asymptomatique ou pauci symptomatique, et le plus souvent découverte lors d’un examen d’imagerie ou d’endoscopie. Nous rapportons un cas de pneumatose iléale compliquée d’un volvulus sur bride chez un patient jamais opéré auparavant

Évaluation des propriétés antimicrobiennes de Pterocarpus erinaceus

Cette étude s’est appuyée sur des données d’enquêtes ethnobotaniques effectuées dans la Région centrale du Togo dans un contexte de valorisation de la flore médicinale. L’étude a permis de ressortir la fréquente utilisation de Pterocarpus erinaceus et Daniella oliveri, dans le traitement de maladies infectieuses. Pour tester l’efficacité de ces deux plantes, des tests ont été effectués sur une bactérie, Staphylococcus aureus et une levure, Candida albicans, des germes souvent impliqués dans des infections. Des extractions ont été réalisées sur les différents organes de ces plantes par épuisement de solvant et par extraction totale hydroalcoolique. Les feuilles, écorces de tronc, écorces de racines et racines des deux (02) plantes se sont révélées actives sur les deux germes avec une CMI variant de 1,875 à 30 mg/ml. La présence d’alcaloïdes, flavonoïdes, tanins, saponines et anthracènes dans ces extraits révélés par l’analyse phytochimique seraient à l’origine de ces activités. Ces résultats justifient l’utilisation de ces deux plantes dans le traitement de certaines onychomycoses et candidoses en médecine traditionnelle dans la préfecture de Tchamba au Togo.Mots clés : Pterocarpus erinaceus, Daniellia oliveri, propriétés antimicrobiennes, phytochimie

Field–Temperature Phase Diagram of Intergrain Ordering in Superconducting Ceramic YBCO

The ceramic YBa2Cu4O8 superconductor composed of submicron grains is considered a random Josephson-coupled network containing the so-called π junctions and shows successive phase transitions. With decreasing temperature, first the intragrain superconductive transition occurs inside each grain at T c1 and then the chiral-glass transition occurs among the grains at T c2 (< T c1). The third transition at T c3 (< T c2) is the intergrain superconducting transition. We measured the nonlinear susceptibility and resistivity of the ceramic YBa2Cu4O8 superconductor to determine the field dependences of the transition temperatures T c2 and T c3. The phase diagram of the intergrain ordering is discussed in light of the result predicted by Kawamura.29th International Symposium on Superconductivity (ISS2016), 13–15 December 2016, Tokyo, Japa

Analysis of Relaxation Time in Random Walk with Jumps

We study the relaxation time in the random walk with jumps. The random walk with jumps combines random walk based sampling with uniform node sampling and improves the performance of network analysis and learning tasks. We derive various conditions under which the relaxation time decreases with the introduction of jumps.Comment: 13 page

Determination of density and concentration from fluorescent images of a gas flow

A fluorescent image analysis procedure to determine the distribution of species concentration and density in a gas flow is proposed. The fluorescent emission is due to the excitation of atoms/molecules of a gas that is intercepted by an electron blade. The intensity of the fluorescent light is proportional to the local number density of the gas. When the gas flow is a mixture of different species, this proportionality can be exploited to extract the contribution associated to the species from the spectral superposition acquired by a digital camera. This yields a method that simultaneously reveals species concentrations and mass density of the mixture. The procedure is applied to two under-expanded sonic jets discharged into a different gas ambient - Helium into Argon and Argon into Helium - to measure the concentration and density distribution along the jet axis and across it. A comparison with experimental and numerical results obtained by other authors when observing under-expanded jets at different Mach numbers is made with the density distribution along the axis of the jet. This density distribution appears to be self-similar.Comment: New figures in portable .eps forma

Uncommon mimics of appendicitis: Giant mucocele

Appendiceal mucocele is an infrequent but well recognized entity that can present with a variety of clinical syndromes or can be asymptomatic and discovered incidentally. A 55 years old patient was admitted in the emergency department for acute right lower quadrant pain. A diagnosis of appendicitis was made. At operation an appendiceal mucocele was found. An appendectomy was performed. The diagnosis of appendiceal mucocele is an important one in that it can be associated with malignancies and other serious gastrointestinal, ovarian, and urological complications