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排序方式: 共有264条查询结果,搜索用时 31 毫秒
1.
Optimum diversity and worst-case partial-band noise jamming conditions have been derived for noncoherent energy detection of frequency-hopped (FH)M -ary frequency-shift keyed (MFSK) signals using a soft-chip decision suboptimum linear combining metric with perfect jamming-state side information. However, the assumption implicit in previous publications is that the error rate is first maximized over the jammer's partial-band duty factor for arbitrary diversity, and the result is then minimized over the amount of diversity. This paper shows that if the order of optimization is reversed, different conditions and performance are produced; that is, the previous solution is not a saddlepoint. This introduces some game-theoretic considerations for the communicator and the jammer, the risks and advantages of which are explored. 相似文献
2.
Levitt Mary J.; Guacci-Franco Nathalie; Levitt Jerome L. 《Canadian Metallurgical Quarterly》1993,29(5):811
Little is known about social networks in childhood, and even less is known about the networks of ethnically diverse children. Interviews were conducted with 333 African-American, Anglo/European-American, and Hispanic-American public school children in Grades 1–2, 4–5, and 8–9. The research was based on the social convoy model (R. L. Kahn and T. C. Antonucci, 1980), in which social networks are viewed as dynamic hierarchic structures affording the provision of support across the life span. An adapted convoy mapping procedure evidenced good test–retest reliability at all ages, and convoy support measures were associated with self-concept and teacher-rated sociability and mood. For all ethnic groups, the results reflect the significance of close family relations across age, an increase in involvement with extended family in middle-childhood, and the emergent role of peers as support providers in adolescence. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
CG Tankersley RS Fitzgerald RC Levitt WA Mitzner SL Ewart SR Kleeberger 《Canadian Metallurgical Quarterly》1997,82(3):874-881
The purpose of the present study was to determine the genetic control of baseline breathing pattern by examining the mode of inheritance between two inbred murine strains with differential breathing characteristics. Specifically, the rapid, shallow phenotype of the C57BL/6J (B6) strain is consistently distinct from the slow, deep phenotype of the C3H/HeJ (C3) strain. The response distributions of segregant and nonsegregant progeny were compared with the two progenitor strains to determine the mode of inheritance for each ventilatory characteristic. The BXH recombinant inbred (RI) strains derived from the B6 and C3 progenitors were examined to establish strain distribution patterns for each ventilatory trait. To establish the mode of inheritance, baseline breathing frequency (f), tidal volume, and inspiratory time (TI) were measured five times in each of 178 mature male animals from the two progenitor strains and their progeny by using whole body plethysmography. With respect to f and TI, the two progenitor strains were consistently distinct, and segregation analyses of the inheritance pattern suggest that the most parsimonious genetic model for response distributions of f and TI is a two-loci model. In similar experiments conducted on 82 mature male animals from 12 BXH RI strains, each parental phenotype was represented by one or more of the RI strains. Intermediate phenotypes emerged to confirm the likelihood that parental strain differences in f and TI were determined by more than one locus. Taken together, these studies suggest that the phenotypic difference in baseline respiratory timing between male B6 and C3 mice is best explained by a genetic model that considers at least two loci as major determinants. 相似文献
4.
MXene Yarn Supercapacitors: High‐Performance Biscrolled MXene/Carbon Nanotube Yarn Supercapacitors (Small 37/2018)
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5.
The author discussed the increase in the frequency of traumatic paralyses of the ocular muscles, and reported 6 cases of inferior oblique muscle paresis caused by local blunt or sharp traumas (haematoma, contusion, rupture, incarceration) and one case of traumatic Brownian pseudo-paralysis. The localisation of the injuries in 3 cases was on the inferior temporal part and in the other 3 cases on the superior part of the bulbar conjunctiva. Atypical horizontal deviation and characteristic vertical deviation, torsion and torticollis were observed in the majority of cases. One patient recovered spontaneously. 3 patients became asymptomatic after correction by prisms and one after recession of contralateral superior rectus muscle. The symptoms remained unchanged in the case of a "blow out" fracture (in spite of operation) and a Brown's syndrome (without treatment). 相似文献
6.
A. Abrizah Mohammadamin Erfanmanesh Vala Ali Rohani Mike Thelwall Jonathan M. Levitt Fereshteh Didegah 《Scientometrics》2014,101(1):569-585
This paper analyses the information science research field of informetrics to identify publication strategies that have been important for its successful researchers. The study uses a micro-analysis of informetrics researchers from 5,417 informetrics papers published in 7 core informetrics journals during 1948–2012. The most productive informetrics researchers were analysed in terms of productivity, citation impact, and co-authorship. The 30 most productive informetrics researchers of all time span several generations and seem to be usually the primary authors of their research, highly collaborative, affiliated with one institution at a time, and often affiliated with a few core European centres. Their research usually has a high total citation impact but not the highest citation impact per paper. Perhaps surprisingly, the US does not seem to be good at producing highly productive researchers but is successful at producing high impact researchers. Although there are exceptions to all of the patterns found, researchers wishing to have the best chance of being part of the next generation of highly productive informetricians may wish to emulate some of these characteristics. 相似文献
7.
Alfred S. Levitt 《Journal of the American Planning Association. American Planning Association》2013,79(2):80-81
Planning initiative on the part of individual groups and communities within urban areas has been made necessary by the increasing bureaucratization and technical basis of decisions in current urban society. The efforts of advocate planners to represent these groups are made difficult because of their frequent lack of homogeneity, community feeling, and common interests in action. The treatment of local areas as “communities” of homogeneous interests can result in severe damage to the interest of their weakest inhabitants. Further, it is difficult to draw low-income families into the framework of planning, and to evoke their concern for the planning issues normally posed by the local establishment. Thus it is necessary to carefully generate viable issues in the work and maintain a consciousness of the interrelation of technical and political matters at all levels. The advocate planner's need to evoke and formulate issues maizes him dangerously similar to other manipulators of the poor's interests. One of the most difficult kinds of issues is the type like transportation which, although generated at the community level, must be studied and argued at the metropolitan scale with the consequent loss of a clearly identified client group. Advocacy planning takes many forms depending on its sponsorship. In spite of its problems, it fills a crucial need for managing latent conflict in the cities and for humanizing public action. 相似文献
8.
Advanced Monte Carlo simulations of the adsorption of chiral alcohols in a homochiral metal‐organic framework
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Zhiwei Qiao Ariana Torres‐Knoop David Dubbeldam David Fairen‐Jimenez Jian Zhou Randall Q. Snurr 《American Institute of Chemical Engineers》2014,60(6):2324-2334
Grand canonical Monte Carlo (GCMC) simulations with configurational biasing were used to study the enantioselective adsorption of four alkanols in a homochiral metal‐organic framework, known as hybrid organic‐inorganic zeolite analogue HOIZA‐1. Conventional GCMC simulations are not able to converge satisfactorily for this system due to the tight fit of the chiral alcohols in the narrow pores. However, parallel tempering and parallel mole‐fraction GCMC simulations overcome this problem. The simulations show that the enantioselective adsorption of the different (R,S)‐alkanols is due to the specific geometry of the chiral molecules relative to the pore size and shape. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2324–2334, 2014 相似文献
9.
Velichka Strijkova-Kenderova Svetla Todinova Tonya Andreeva Desislava Bogdanova Ariana Langari Avgustina Danailova Sashka Krumova Elena Zlatareva Nikolay Kalaydzhiev Ivan Milanov Stefka G. Taneva 《International journal of molecular sciences》2022,23(1)
Human red blood cells (RBCs) are unique cells with the remarkable ability to deform, which is crucial for their oxygen transport function, and which can be significantly altered under pathophysiological conditions. Here we performed ultrastructural analysis of RBCs as a peripheral cell model, looking for specific signatures of the neurodegenerative pathologies (NDDs)—Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD), utilizing atomic force (AFM) and conventional optical (OM) microscopy. We found significant differences in the morphology and stiffness of RBCs isolated from patients with the selected NDDs and those from healthy individuals. Neurodegenerative pathologies’ RBCs are characterized by a reduced abundance of biconcave discoid shape, lower surface roughness and a higher Young’s modulus, compared to healthy cells. Although reduced, the biconcave is still the predominant shape in ALS and AD cells, while the morphology of PD is dominated by crenate cells. The features of RBCs underwent a marked aging-induced transformation, which followed different aging pathways for NDDs and normal healthy states. It was found that the diameter, height and volume of the different cell shape types have different values for NDDs and healthy cells. Common and specific morphological signatures of the NDDs were identified. 相似文献
10.
Jorge Berlanga-Acosta Maday Fernndez-Mayola Yssel Mendoza-Marí Ariana García-Ojalvo Indira Martinez-Jimenez Nadia Rodriguez-Rodriguez Raymond J. Playford Osvaldo Reyes-Acosta Laura Lopez-Marín Gerardo Guilln-Nieto 《International journal of molecular sciences》2022,23(3)
Lower-extremity arterial disease is a major health problem with increasing prevalence, often leading to non-traumatic amputation, disability and mortality. The molecular mechanisms underpinning abnormal vascular wall remodeling are not fully understood. We hypothesized on the existence of a vascular tissue memory that may be transmitted through soluble signaling messengers, transferred from humans to healthy recipient animals, and consequently drive the recapitulation of arterial wall thickening and other vascular pathologies. We examined the effects of the intralesional infiltration for 6 days of arteriosclerotic popliteal artery-derived homogenates (100 µg of protein) into rats’ full-thickness wounds granulation tissue. Animals infiltrated with normal saline solution or healthy brachial arterial tissue homogenate obtained from traumatic amputation served as controls. The significant thickening of arteriolar walls was the constant outcome in two independent experiments for animals receiving arteriosclerotic tissue homogenates. This material induced other vascular morphological changes including an endothelial cell phenotypic reprogramming that mirrored the donor’s vascular histopathology. The immunohistochemical expression pattern of relevant vascular markers appeared to match between the human tissue and the corresponding recipient rats. These changes occurred within days of administration, and with no cross-species limitation. The identification of these “vascular disease drivers” may pave novel research avenues for atherosclerosis pathobiology. 相似文献