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101.
102.
On Probabilistic Networks for Selection, Merging, and Sorting 总被引:1,自引:0,他引:1
We study comparator networks for selection, merging, and sorting that output the correct result with high probability, given
a random input permutation. We prove tight bounds, up to constant factors, on the size and depth of probabilistic (n,k)-selection networks. In the case of (n, n/2)-selection, our result gives a somewhat surprising bound of on the size of networks of success probability in , where δ is an arbitrarily small positive constant, thus comparing favorably with the best previously known solutions, which have
size . We also prove tight bounds, up to lower-order terms, on the size and depth of probabilistic merging networks of success
probability in , where δ is an arbitrarily small positive constant. Finally, we describe two fairly simple probabilistic sorting networks of success
probability at least and nearly logarithmic depth.
Received January 22, 1996, and in final form February 14, 1997. 相似文献
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The purpose of this study is to find the correlation between middle latency auditory evoked potentials (MLAEP) and sound activated single photon emission computed tomography (SPECT) studies. This study was performed on six normal right-handed volunteers with a mean age of 35.2 +/- 7.6 years, using the split-dose technique. First, a SPECT study was performed on subjects in blinded, awake and silent states. After bilateral ears were stimulated with a click sound, MLAEP and a second SPECT study were performed. Subtraction of the first SPECT from the second SPECT revealed a statistically significant increase of cerebral blood flow (CBF) in the bilateral superior temporal region. Bilateral Na amplitudes of MLAEP had a statistically significant and good correlation with the percentages of CBF changes in the bilateral superior temporal region. The superior temporal cerebral blood flow activation can be expressed by electrophysiological activation. Moreover, correlation during the left Na components and left frontal and occipital lobe are discussed. 相似文献
105.
G Gutiérrez-Ospina L Saum AS Calikoglu S Díaz-Cintra FA Barrios AJ D'Ercole 《Canadian Metallurgical Quarterly》1997,8(13):2907-2911
To evaluate whether insulin-like growth factor-I (IGF-I) modulates neural activity in vivo, relative levels of brain [3H]2-deoxyglucose (2DG) uptake were compared in adult behaving and anesthetized wild type (wt) mice, and transgenic (Tg) mice with either brain IGF-I overexpression or ectopic brain expression of IGF binding protein-1 (IGFBP-1). Overall, awake behaving IGF-I Tg mice showed significant increases in brain 2DG uptake compared with wt and IGFBP-1 Tg mice. These differences were eliminated after anesthesia. 2DG uptake was similar in awake behaving, and anesthetized wt and IGFBP-1 Tg mice. Our observations thus suggest that IGF-I increases neural activity levels in vivo, and that it is not involved in regulating glucose consumption in the adult brain. 相似文献
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OBJECTIVE: To determine whether neurological and psychiatric symptoms predict survival time among patients with Alzheimer disease (AD) after adjusting for the influence of sociodemographic variables, health conditions, and dementia severity separately for men and women. DESIGN: The sample consisted of 936 men and women diagnosed as having probable or possible AD at 1 of 7 Alzheimer's Disease Diagnostic and Treatment Centers throughout California from 1986 through 1990. Data on dementia severity, comorbid conditions, and demographic characteristics were collected at the time of AD diagnosis. Data on vital status and dates of death were obtained by linking the patient file to several administrative databases maintained by the California State and federal governments. The mean length of follow-up was 31 months. Data were analyzed with Kaplan-Meier survival curves and Cox proportional hazards models. RESULTS: Men had shorter survival times than did women (log-rank test, 30.93, P < .001). Among men, but not women, survival times were negatively associated with selected neurological and psychiatric symptoms. Among women, but not men, a history of cardiovascular conditions was associated with poorer survival. CONCLUSIONS: Patterns of survival and predictors of survival time among patients with AD differ by sex. Future studies of survival and progression of AD need to examine men and women separately. 相似文献
108.
I Casta?o Zapatero FA Pastor Quirante ER Redondo Luciá?ez 《Canadian Metallurgical Quarterly》1997,48(8):630-634
A 1488-bp fragment of bovine retina guanylate cyclase B gene encoding the catalytic and dimerizing domains as well as part of the protein kinase domain was expressed in Escherichia coli cells. The expression product was obtained as inclusion bodies and solubilized in 6 M guanidine hydrochloride. The fragment of guanylate cyclase B is a dimer close in catalytic activity to the native enzyme. 相似文献
109.
The high affinity growth hormone-binding protein (GHBP) circulates in human blood and represents the extracellular domain of the growth hormone (GH) receptor. It is well known that repetitive bouts of endurance type exercise result in increased integrated GH secretion. As the effects of chronic exercise on plasma GHBP levels have never been studied systematically, we investigated the effect of 2 weeks of intense endurance training on plasma GHBP as well as on plasma insulin-like growth factor (IGF)-I levels in 10 healthy, young, non-obese men. IGF-I was measured as an indicator of the effects of GH release. We also studied 10 control subjects matched for sex, age and activity, who were instructed not to change their customary activities. GHBP was determined by FPLC size exclusion chromatography and subsequent Scatchard plot analysis of the binding data; IGF-I levels were measured by RIA. The results showed that plasma IGF-I and GHBP levels were increased in the subjects who followed the training program. IGF-I and GHBP changed from 252 +/- 56 ng/ml and 912 +/- 59 pmol/l before training, to 344 +/- 61 ng/ml (p < 0.01) and 1020 +/- 48 pmol/l (p < 0.01), respectively. Another effect of the training was that the aerobic capacity of these subjects was better utilized and endurance was improved. In contrast, plasma IGF-I, GHBP, utilization of aerobic capacity and endurance did not change significantly in the control subjects. We conclude that two weeks of strenuous endurance training lead to increased plasma IGF-I and high affinity GHBP levels. 相似文献
110.