1,442 research outputs found
Inventaire de la faune mammalogique dâune forĂȘt urbaine, le Parc National du Banco, CĂŽte dâIvoire
Le Parc National du Banco,forĂȘt sempervirente Ă lâintĂ©rieure de la capitale Ă©conomique de la CĂŽte dâivoire a toujours constituĂ© une curiositĂ©. Dans la pĂ©riode du 11 avril 2013 au 19 avril 2013 nous avons effectuĂ© dans cette forĂȘt un inventaire des mammifĂšres. Les mĂ©thodes utilisĂ©es sont celles des transects linĂ©aires pour les grands mammifĂšres et la mĂ©thode de capture pour la plupart des petits mammifĂšres. Nos rĂ©sultats indiquent que, les grands mammifĂšres rencontrĂ©s sont constituĂ©s de primates (Cercopithecus campbelli lowei, Cercopithecus petaurista et Pan troglodytes verus), dâongulĂ©s (Tragelaphus scriptus, Philantomba maxwellii, et Neotragus pygmaeus) et de carnivores (Genetta tigrina, Crossarchus obscurus et Civettictis civetta). Dâune maniĂšre gĂ©nĂ©rale, lâindice kilomĂ©trique dâabondance de ces groupes taxonomiques est faible (0,022 Ă 0,12). Le chimpanzĂ© dâAfrique de lâOuest (Pan troglodytes verus), espĂšce en danger selon lâUnion pour la Conservation de la Nature existe encore dans cette forĂȘt. Au niveau des petits mammifĂšres plusieurs espĂšces de rongeurs, dâinsectivores et de chiroptĂšres ont Ă©tĂ© inventoriĂ©es lors de notre Ă©tude. Parmi ces espĂšces, la chauve-souris paillĂ©e (Eidolon helvum) et la Musaraigne de Wimmer (Crocidura wimmeri) sont en danger dâextinction selon lâUICN. Toutefois, la prĂ©sence humaine Ă proximitĂ© du parc constitue une rĂ©elle menace pour son intĂ©gritĂ©.Mots clĂ©s : MammifĂšres, chimpanzĂ©, chauve-souris, insectivore
Quantum Communications with Compressed Decoherence Using Bright Squeezed Light
We propose a scheme for long-distance distribution of quantum entanglement in
which the entanglement between qubits at intermediate stations of the channel
is established by using bright light pulses in squeezed states coupled to the
qubits in cavities with a weak dispersive interaction. The fidelity of the
entanglement between qubits at the neighbor stations (10 km apart from each
other) obtained by postselection through the balanced homodyne detection of 7
dB squeezed pulses can reach F=0.99 without using entanglement purification, at
same time, the probability of successful generation of entanglement is 0.34.Comment: 4 pages, 2 figure
Molecular Mechanisms of the Diabetogenic Effects of Arsenic: Inhibition of Insulin Signaling by Arsenite and Methylarsonous Acid
BACKGROUND: Increased prevalences of diabetes mellitus have been reported among individuals chronically exposed to inorganic arsenic (iAs). However, the mechanisms underlying the diabetogenic effects of iAs have not been characterized. We have previously shown that trivalent metabolites of iAs, arsenite (iAs(III)) and methylarsonous acid (MAs(III)) inhibit insulin-stimulated glucose uptake (ISGU) in 3T3-L1 adipocytes by suppressing the insulin-dependent phosphorylation of protein kinase B (PKB/Akt). OBJECTIVES: Our goal was to identify the molecular mechanisms responsible for the suppression of PKB/Akt phosphorylation by iAs(III) and MAs(III). METHODS: The effects of iAs(III) and MAs(III) on components of the insulin-activated signal transduction pathway that regulate PKB/Akt phosphorylation were examined in 3T3-L1 adipocytes. RESULTS: Subtoxic concentrations of iAs(III) or MAs(III) had little or no effect on the activity of phosphatidylinositol 3-kinase (PI-3K), which synthesizes phosphatidylinositol-3,4,5-triphosphate (PIP(3)), or on phosphorylation of PTEN (phosphatase and tensin homolog deleted on chromosome ten), a PIP(3) phosphatase. Neither iAs(III) nor MAs(III) interfered with the phosphorylation of 3-phosphoinositide-dependent kinase-1 (PDK-1) located downstream from PI-3K. However, PDK-1 activity was inhibited by both iAs(III) and MAs(III). Consistent with these findings, PDK-1-catalyzed phosphorylation of PKB/Akt(Thr308) and PKB/Akt activity were suppressed in exposed cells. In addition, PKB/Akt(Ser473) phosphorylation, which is catalyzed by a putative PDK-2, was also suppressed. Notably, expression of constitutively active PKB/Akt restored the normal ISGU pattern in adipocytes treated with either iAs(III) or MAs(III). CONCLUSIONS: These results suggest that inhibition of the PDK-1/PKB/Akt-mediated transduction step is the key mechanism for the inhibition of ISGU in adipocytes exposed to iAs(III) or MAs(III), and possibly for impaired glucose tolerance associated with human exposures to iAs
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The nature of ferromagnetism in the chiral helimagnet Cr1/3NbS2
The chiral helimagnet Cr1/3NbS2 hosts exotic spin textures, whose influence on the magneto-transport properties make this material an ideal candidate for future spintronic applications. To date, the interplay between macroscopic magnetic and transport degrees of freedom is believed to result from a reduction in carrier scattering following spin order. Here, we present electronic structure measurements across the helimagnetic transition temperature TC that challenges this view. We show that the Fermi surface is comprised of strongly hybridized Nb- and Cr-derived electronic states, and that spectral weight close to the Fermi level increases anomalously as the temperature is lowered below TC. These findings are rationalized on the basis of first principle density functional theory calculations, which reveal a large nearest-neighbor exchange energy, suggesting the interaction between local spin moments and hybridized Nb- and Cr-derived itinerant states to go beyond the perturbative interaction of Ruderman-Kittel-Kasuya-Yosida, suggesting instead a mechanism rooted in a Hundâs exchange interaction
SuizidprÀvention: Vorgehensweisen und Wirksamkeit
According to official statistics every year 11,000 persons in Germany die from suicide. 20 years ago nearly 19,000 suicides were registered. What are the causes for this decrease? Do suicide preventive measures contribute to the reduction of suicide rates? Different universal prevention strategies ( e. g. restriction of access to means) and selective approaches ( programs for special high-risk groups; e. g. patients after attempted suicide) are presented and discussed regarding their preventive value. In most cases it is hardly possible to scientifically prove the efficacy of suicide prevention strategies. Neither the role of psychosocial interventions nor the impact of psychotropic agents can be sufficiently quantified. Due to various methodological reasons ( e. g. small sample sizes and the lack of randomization), interpretation of the data is difficult. In terms of a comprehensive approach of suicide prevention a combination of different activities should be most adequate in the long run
Salt-inducible kinases (SIKs) regulate TGFÎČ-mediated transcriptional and apoptotic responses
Simultaneous Effects of Light Intensity and Phosphorus Supply on the Sterol Content of Phytoplankton
Sterol profiles of microalgae and their change with environmental conditions are of great interest in ecological food web research and taxonomic studies alike. Here, we investigated effects of light intensity and phosphorus supply on the sterol content of phytoplankton and assessed potential interactive effects of these important environmental factors on the sterol composition of algae. We identified sterol contents of four common phytoplankton genera, Scenedesmus, Chlamydomonas, Cryptomonas and Cyclotella, and analysed the change in sterol content with varying light intensities in both a high-phosphorus and a low-phosphorus approach. Sterol contents increased significantly with increasing light in three out of four species. Phosphorus-limitation reversed the change of sterol content with light intensity, i.e., sterol content decreased with increasing light at low phosphorus supply. Generally sterol contents were lower in low-phosphorus cultures. In conclusion, both light and phosphorus conditions strongly affect the sterol composition of algae and hence should be considered in ecological and taxonomic studies investigating the biochemical composition of algae. Data suggest a possible sterol limitation of growth and reproduction of herbivorous crustacean zooplankton during summer when high light intensities and low phosphorus supply decrease sterol contents of algae
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