772 research outputs found
Prévalence et facteurs de risque de la fièvre aphteuse dans le marché à bétail de Garoua-Boulai et dans la zone de transhumance du Lom et Djerem à l’Est du Cameroun
La fièvre aphteuse (FA) est une maladie transfrontalière qui affecte les ongulés domestiques et sauvages. Elle joue un rôle très important en économie du fait de sa morbidité élevée et de sa restriction du commerce international. En vue de déterminer la prévalence de la FA bovine et les facteurs de risque de transmission de la maladie au marché à bétail de Garoua-Boulaï et dans la zone de transhumance du département du Lom et Djerem à l’Est-Cameroun, une étude rétrospective et transversale a été menée de juin à décembre 2018. Au marché à bétail, l’étude a porté sur l’observation des signes cliniques caractéristiques sur des animaux suspects. Ainsi, 58 bovins atteints de FA ont été identifiés parmi les 614 bovins suspects, soit une prévalence clinique globale de 9,44% (IC95% : 7,13% - 11,76%). Les facteurs internes tels que le sexe n’ont pas influencé la prévalence de la FA. Dans la zone de transhumance, la prévalence rapportée au niveau individuel était de 26,77%. Tous les éleveurs connaissent la FA et ont cité plus de 3 signes cliniques caractéristiques de la maladie. Le fait de considérer la FA comme une maladie mineure, la faible connaissance des sources, des réservoirs et du mode de contamination du virus aphteux par toute la chaine de valeur bovine, expliquent l’endémicité de la maladie dans ces zones.Mots clés : Prévalence, facteurs de risque, fièvre aphteuse bovine, Garoua-Boulai, Lom et Djerem
Electronic structure near the 1/8-anomaly in La-based cuprates
We report an angle resolved photoemission study of the electronic structure
of the pseudogap state in \NdLSCO ( K). Two opposite dispersing Fermi
arcs are the main result of this study. The several scenarios that can explain
this observation are discussed.Comment: A high-resolution version can be found at
http://lns.web.psi.ch/lns/download/Pockets/arXiv.pd
Origins of large critical temperature variations in single layer cuprates
We study the electronic structures of two single layer superconducting
cuprates, TlBaCuO (Tl2201) and
(BiPb)(SrLa)CuO (Bi2201) which
have very different maximum critical temperatures (90K and 35K respectively)
using Angular Resolved Photoemission Spectroscopy (ARPES). We are able to
identify two main differences in their electronic properties. First, the shadow
band that is present in double layer and low T single layer cuprates
is absent in Tl2201. Recent studies have linked the shadow band to structural
distortions in the lattice and the absence of these in Tl2201 may be a
contributing factor in its T.Second, Tl2201's Fermi surface (FS)
contains long straight parallel regions near the anti-node, while in Bi2201 the
anti-nodal region is much more rounded. Since the size of the superconducting
gap is largest in the anti-nodal region, differences in the band dispersion at
the anti-node may play a significant role in the pairing and therefore affect
the maximum transition temperature.Comment: 6 pages, 5 figures,1 tabl
Spectroscopic evidence for preformed Cooper pairs in the pseudogap phase of cuprates
Angle-resolved photoemission on underdoped LaSrCuO
reveals that in the pseudogap phase, the dispersion has two branches located
above and below the Fermi level with a minimum at the Fermi momentum. This is
characteristic of the Bogoliubov dispersion in the superconducting state. We
also observe that the superconducting and pseudogaps have the same d-wave form
with the same amplitude. Our observations provide direct evidence for preformed
Cooper pairs, implying that the pseudogap phase is a precursor to
superconductivity
Induction of haem synthesis in Hep G2 human hepatoma cells by dimethyl sulphoxide. A transcriptionally activated event
Acylpeptide hydrolase: inhibitors and some active site residues of the human enzyme.
Acylpeptide hydrolase may be involved in N-terminal deacetylation of nascent polypeptide chains and of bioactive peptides. The activity of this enzyme from human erythrocytes is sensitive to anions such as chloride, nitrate, and fluoride. Furthermore, blocked amino acids act as competitive inhibitors of the enzyme. Acetyl leucine chloromethyl ketone has been employed to identify one active site residue as His-707. Diisopropylfluorophosphate has been used to identify a second active site residue as Ser-587. Chemical modification studies with a water-soluble carbodiimide implicate a carboxyl group in catalytic activity. These results and the sequence around these active site residues, especially near Ser-587, suggest that acylpeptide hydrolase contains a catalytic triad. The presence of a cysteine residue in the vicinity of the active site is suggested by the inactivation of the enzyme by sulfhydryl-modifying agents and also by a low amount of modification by the peptide chloromethyl ketone inhibitor. Ebelactone A, an inhibitor of the formyl aminopeptidase, the bacterial counterpart of eukaryotic acylpeptide hydrolase, was found to be an effective inhibitor of this enzyme. These findings suggest that acylpeptidase hydrolase is a member of a family of enzymes with extremely diverse functions
Three-Dimensional Fermi Surface of Overdoped La-Based Cuprates
We present a soft x-ray angle-resolved photoemission spectroscopy study of
the overdoped high-temperature superconductors LaSrCuO and
LaEuSrCuO. In-plane and out-of-plane components of
the Fermi surface are mapped by varying the photoemission angle and the
incident photon energy. No dispersion is observed along the nodal
direction, whereas a significant antinodal dispersion is identified.
Based on a tight-binding parametrization, we discuss the implications for the
density of states near the van-Hove singularity. Our results suggest that the
large electronic specific heat found in overdoped LaSrCuO can
not be assigned to the van-Hove singularity alone. We therefore propose quantum
criticality induced by a collapsing pseudogap phase as a plausible explanation
for observed enhancement of electronic specific heat
A heat-inducible nuclear factor that binds to the heat-shock element of the human haem oxygenase gene
The CoESCA station at BESSY: Auger electron–photoelectron coincidences from surfaces demonstrated for Ag MNN
In this work, we present the CoESCA station for electron–electron coincidence spectroscopy from surfaces, built in a close collaboration between Uppsala University and Helmholtz-Zentrum Berlin at the BESSY II synchrotron facility in Berlin, Germany. We start with a detailed overview of previous work in the field of electron–electron coincidences, before we describe the CoESCA setup and its design parameters. The system is capable of recording shot-to-shot resolved 6D coincidence datasets, i.e. the kinetic energy and the two take off angles for both coincident electrons. The mathematics behind extracting and analysing these multi-dimensional coincidence datasets is introduced, with a focus on coincidence statistics, resulting in fundamental limits of the signal-to-noise ratio and its implications for acquisition times and the size of the raw data stream. The functionality of the CoESCA station is demonstrated for the example of Auger electron–photoelectron coincidences from silver surfaces for photoelectrons from the Ag 3d core levels and their corresponding MNN Auger electrons. The Auger spectra originating from the different core levels, 3d and 3d could be separated and further, the two-hole state energy distributions were determined for these Auger decay channels
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