3,158 research outputs found

    A program to develop a high-energy density primary battery with a minimum of 200 watt hours per pound of total battery weight Eighth quarterly report, 1 Apr. - 30 Jun. 1966

    Get PDF
    Electrochemical characteristics of lithium in various electrolytes and magnesium in aluminum chloride-acetonitrile studied by voltammetric sweep metho

    Fibrosarcoma esplénico primario en un perro

    Get PDF
    Se describe un caso de fibrosarcoma esplénico primario, con metástasis múltiples, en un perro mestizo macho, de ocho años de edad. Clínicamente el animal presentaba un cuadro de insuficiencia hepática. Mediante la necropsia y el estudio histológico se llegó al diagnóstico definitivo.A case of primary splenic fibrosarcoma, with multiple metastasis, in a male eight-year old mixed-breed dog is described. The animal showed clinical signs corresponding with an hepatic failure. Necropsy and a subsequent histopathologic study lead to the final diagnosis

    Synaptic Adhesion Molecules Regulate the Integration of New Granule Neurons in the Postnatal Mouse Hippocampus and their Impact on Spatial Memory.

    Get PDF
    Postnatal hippocampal neurogenesis induces network remodeling and may participate to mechanisms of learning. In turn, the maturation and survival of newborn neurons is regulated by their activity. Here, we tested the effect of a cell-autonomous overexpression of synaptic adhesion molecules on the maturation and survival of neurons born postnatally and on hippocampal-dependent memory performances. Families of adhesion molecules are known to induce pre- and post-synaptic assembly. Using viral targeting, we overexpressed three different synaptic adhesion molecules, SynCAM1, Neuroligin-1B and Neuroligin-2A in newborn neurons in the dentate gyrus of 7- to 9-week-old mice. We found that SynCAM1 increased the morphological maturation of dendritic spines and mossy fiber terminals while Neuroligin-1B increased spine density. In contrast, Neuroligin-2A increased both spine density and size as well as GABAergic innervation and resulted in a drastic increase of neuronal survival. Surprisingly, despite increased neurogenesis, mice overexpressing Neuroligin-2A in new neurons showed decreased memory performances in a Morris water maze task. These results indicate that the cell-autonomous overexpression of synaptic adhesion molecules can enhance different aspects of synapse formation on new neurons and increase their survival. Furthermore, they suggest that the mechanisms by which new neurons integrate in the postnatal hippocampus conditions their functional implication in learning and memory

    Fluctuating selection models and Mcdonald-Kreitman type analyses

    Get PDF
    It is likely that the strength of selection acting upon a mutation varies through time due to changes in the environment. However, most population genetic theory assumes that the strength of selection remains constant. Here we investigate the consequences of fluctuating selection pressures on the quantification of adaptive evolution using McDonald-Kreitman (MK) style approaches. In agreement with previous work, we show that fluctuating selection can generate evidence of adaptive evolution even when the expected strength of selection on a mutation is zero. However, we also find that the mutations, which contribute to both polymorphism and divergence tend, on average, to be positively selected during their lifetime, under fluctuating selection models. This is because mutations that fluctuate, by chance, to positive selected values, tend to reach higher frequencies in the population than those that fluctuate towards negative values. Hence the evidence of positive adaptive evolution detected under a fluctuating selection model by MK type approaches is genuine since fixed mutations tend to be advantageous on average during their lifetime. Never-the-less we show that methods tend to underestimate the rate of adaptive evolution when selection fluctuates
    corecore