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This study compares the weight of the human brain to gestational age and body dimensions. A new formula for calculating the rate of growth is proposed. It consists of a second order polynomial function: Y = A0 + A1X + A2X2, in which Y is brain weight, body weight, height, or body surface area; X is gestational age in weeks and A0, A1, and A2 are statistically estimated coefficients. In utero, the growth rate is most rapid for body weight, followed in decreasing order by brain weight, body surface area, and height. Brain growth is the same for both sexes in black and white races; it accelerates between the 20th and 45th weeks of gestation. The size of the newborn infant brain is directly related to gestational age and body size and is not determined by sex or race.  相似文献   
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Performance characteristics of pooled rabbit IgG polyclonal anti-C3d are compared with one mouse IgM and three mouse IgG monoclonal anti-C3d antibodies (MAs). IgG MA,s employed singly or in combination, failed to precipitate C3d; by contrast, IgM MA and polyclonal anti-C3d precipitated C3d. Measurements of polyclonal anti-C3d concentration by chemical means and by 125I-C3d radioimmunoassay (RIA) agreed closely. RIA values were 50% of chemical measurement values for three of the four MAs. Use of sucrose density gradient ultracentrifugation to assess MA C3d/anti-C3d molar combining ratios for soluble anti-C3d/C3d was not possible because fast-sedimenting multimeric C3d/anti-C3d complexes did not form. Dissociation and competitive binding studies indicate that (1) two MAs had substantially lower affinities than the other anti-C3d antibodies, and (2) polyclonal anti-C3d recognizes more C3d epitopes than are recognized by individual MAs. The results demonstrate antigenic complexity of C3d fragment and illustrate the difficulties of predicting individual MA performance based on prior experience with polyclonal antibodies.  相似文献   
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To investigate whether the fragile X syndrome is associated with a generalised chromosomal instability, we compared the frequency and distribution of chromosomal breakage in lymphocytes grown in low folate medium from normal subjects and from patients with the syndrome. Although low folate conditions increased the rate of chromosome breakage, no difference in frequency or distribution of chromosomal breakage was found between the two groups. This suggests that the fragile X syndrome is not associated with a generalised chromosome instability expressed in folate deficient medium and assessed in terms of chromosomal breakage.  相似文献   
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This study develops an explanatory framework for fear of neighborhood crime based on respondents' social context and local rates of assault injuries. Rates of assault injuries within zip codes are based on hospital discharge records. We find that only four variables have a significant unique contribution to fear of crime: respondent's sex, perceptions of neighborhood social capital, and the rates of struck by/against assault injuries for the 10–24 and 50+ age groups. We also find that the perception of neighborhood social capital moderates the impact of assault injury rates on fear of crime; those who perceive a high level of neighborhood social capital exhibit less sensitivity to assault injury rates. We include a map of assault injury rates and fear of crime by ZIP Code and describe the community context related to our results. © 2007 Wiley Periodicals, Inc. J Comm Psychol 35: 483–498, 2007.  相似文献   
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