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91.
Neurobiological research in schizophrenia has been hampered by several confounding factors such as the heterogeneity of the illness and the paucity of biological markers. Recent progress in research methods, however, has enabled the improvement in our understanding its pathophysiology. This paper reviews recent neurochemical investigations of schizophrenia and its animal models which were conducted in Japan in the last decade. The research areas reviewed are (i) monoamine and their metabolites in body fluids, (ii) phospholipids and prostaglandins, (iii) neurochemistry in autopsy brains, (iv) immunological measures, (v) magnetic resonance spectroscopy, (vi) regional cerebral blood flows (rCBF), (vii) molecular genetics, and (viii) animal models. It is worth noting that there exist abnormalities of amino acidergic (glutamatergic and GABAergic) neurotransmission as well as monoaminergic (dopaminergic and serotonergic) one in postmortem schizophrenic brains. These abnormalities and also the findings of altered rCBF indicate the existence of disturbed neuronal circuits that contribute to the diverse symptoms of schizophrenia. Also, dysfunction of membrane phospholipids derived from studies on magnetic resonance spectroscopy may underlie negative symptoms in schizophrenia. Given that schizophrenia is considered to comprise a group of disorders with a diverse heterogeneity of etiologies, research in the next decade is expected to identify putative genes that are involved in vulnerability to schizophrenic phenotype. 相似文献
92.
K Senior 《Canadian Metallurgical Quarterly》1997,3(12):528-532
As we uncover the physiological and molecular mechanisms behind human reproduction, we gain the potential to exert more control over our reproductive capabilities. In the past two decades, the prospects for 'infertile' women to bear children, or 'sterile' men to father them, have improved dramatically; recently, women have given birth in their sixties, well beyond their natural menopause. Thanks to developments in contraception, couples can now enjoy an active sex-life without a significant risk of pregnancy, and more accurately control the size and timing of their families. But these new freedoms have a price: they also have the potential to cause demographic distortions, medical harm to individuals and abuse of human rights. 相似文献
93.
94.
95.
K Giesen T Hummel A Stollewerk S Harrison A Travers C Kl?mbt 《Canadian Metallurgical Quarterly》1997,124(12):2307-2316
Two classes of glial cells are found in the embryonic Drosophila CNS, midline glial cells and lateral glial cells. Midline glial development is triggered by EGF-receptor signalling, whereas lateral glial development is controlled by the gcm gene. Subsequent glial cell differentiation depends partly on the pointed gene. Here we describe a novel component required for all CNS glia development. The tramtrack gene encodes two zinc-finger proteins, one of which, ttkp69, is expressed in all non-neuronal CNS cells. We show that ttkp69 is downstream of gcm and can repress neuronal differentiation. Double mutant analysis and coexpression experiments indicate that glial cell differentiation may depend on a dual process, requiring the activation of glial differentiation by pointed and the concomitant repression of neuronal development by tramtrack. 相似文献
96.
A study was undertaken to determine fertility in a group of females who as children had been operated on for appendicitis. The 134 women operated on for appendicitis were reviewed. Their ages ranged from 2-18 years at the time of appendectomy. Our data show that perforated appendicitis before puberty has little if any role in the etiology of tubal infertility. 相似文献
97.
We predict that, for wavelength division multiplexing optical-network applications, an asymmetrically dilated configuration of a 2×2 cross-connect is significantly better in terms of overall crosstalk when the levels of the bar-port crosstalk and the cross-port crosstalk are significantly different from each other, as is the case with optical-frequency filters which utilize grating-assisted coupling. As a verification, we present a simulation study with 2×2 polarization-diversified acousto-optic tunable filters. We present a recursive method to extend the principle of asymmetric dilation to larger-size cross-connect switches, and make a recommendation for an asymmetrically dilated 4×4 cross-connect configuration 相似文献
98.
Neviani A. Meneghesso G. Zanoni E. Hafizi M. Canali C. 《Electron Device Letters, IEEE》1997,18(12):619-621
Impact ionization is a major limiting factor to the maximum operating voltage of InGaAs-based, high-speed transistors. In this work, data on the positive temperature dependence of the electron impact ionization coefficient αn in In0.53Ga0.47As at medium-low electric fields are reported for the first time. The increase of αn with temperature is opposite to the behavior normally observed in most semiconductors. This anomalous behavior implies the onset of a positive feedback between power dissipation and avalanche generation which may adversely affect the power handling capability of In0.53Ga 0.47As-based devices, and which should be taken into account in device thermal modeling. In the experimental procedure, based on the measurement of the multiplication factor M-1 in npn In0.53Ga 0.47As/InP Heterojunction Bipolar Transistors (HBT), particular care has been taken in order to rule out possible spurious, temperature-dependent contributions to the measured multiplication current 相似文献
99.
The effect of high oxide field stress is studied using capacitance-time (C-t) measurements of MOS capacitors. The stress results in parallel shifts of the C-t curve along the time axis. The flatband voltage shift ΔVFB obtained from the initial deep depletion capacitance C(t=0+) follows the same trend as that from the high-frequency C-V characteristics. However, the discrepancy between the two flatband voltages becomes larger as the stress increases due to the effect of interface charges on C-t characteristics. The flatband voltage difference is converted to interface trap density, showing a steady increase of interface trap density with stress, similar to that from low-frequency C-V measurements 相似文献
100.
This paper presents the design criteria, procedure, and implementation of a soft-switched power-factor-correction (PFC) circuit based on the extended-period quasi-resonant (EPQR) principles. All power electronic devices including switches and diodes in the circuit are fully soft switched. The design method is demonstrated in a prototype circuit. The operating principles are confirmed with computer simulation and experimental results. A comparison of the EP-QR operation and zero-voltage-transition (ZVT) pulse-width modulation (PWM) method 相似文献