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51.
Herein, we report on the crystal structures of Nb2AlC and TiNbAlC—actual composition (Ti0.45,Nb0.55)2AlC—compounds determined from Rietveld analysis of neutron diffraction patterns in the 300–1173 K temperature range. The average linear thermal expansion coefficients of a Nb2AlC sample in the a and c directions are, respectively, 7.9(5) × 10?6 and 7.7(5) × 10?6 K?1 on one neutron diffractometer and 7.3(3) × 10?6 and 7.0(2) × 10?6 K?1 on a second diffractometer. The respective values for the (Ti0.45,Nb0.55)2AlC composition—only tested on one diffractometer—are 8.5(3) × 10?6 and 7.5(5) × 10?6 K?1. These values are relatively low compared to other MAX phases. Like other MAX phases, however, the atomic displacement parameters (APDs) show that the Al atoms vibrate with higher amplitudes than the Ti and C atoms, and more along the basal planes than normal to them. When the predictions of the APDs obtained from density functional theory are compared to the experimental results, good quantitative agreement is found for the Al atoms. In case of the Nb and C atoms, the agreement was more qualitative.  相似文献   
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53.
Research on child effects has demonstrated that children's difficult and coercive behavior provokes harsh discipline from adults. Using a genetically sensitive design, the authors tested the limits of child effects on adult behavior that ranged from the normative (corporal punishment) to the nonnormative (physical maltreatment). The sample was a 1994-1995 nationally representative birth cohort of 1,116 twins and their families who participated in the Environmental Risk Longitudinal Study. Results showed that environmental factors accounted for most of the variation in corporal punishment and physical maltreatment. However, corporal punishment was genetically mediated in part, and the genetic factors that influenced corporal punishment were largely the same as those that influenced children's antisocial behavior, suggesting a child effect. The authors conclude that risk factors for maltreatment are less likely to reside within the child and more likely to reside in characteristics that differ between families. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
54.
Range imaging with adaptive color structured light   总被引:9,自引:0,他引:9  
In range sensing with time-multiplexed structured light, there is a trade-off between accuracy, robustness and the acquisition period. In this paper a novel structured light method is described. Adaptation of the number and form of the projection patterns to the characteristics of the scene takes place as part of the acquisition process. Noise margins are matched to the actual noise level, thus reducing the number of projection patterns to the necessary minimum. Color is used for light plane labeling. The dimension of the pattern space are thus increased without raising the number of projection patterns. It is shown that the color of an impinging light plane can be identified from the image of the illuminated scene, even with colorful scenes. Identification is local and does not rely on spatial color sequences. The suggested approach has been implemented and the theoretical results are supported by experiments  相似文献   
55.
Do ill-tempered children become ill-tempered adults? What are the life-course consequences of such an explosive interactional style? What processes can account for the persistence of maladaptive behavior across time and circumstance? To answer these questions, this study used data from the Berkeley Guidance Study (Macfarlane, Allen, & Honzik, 1954) to identify children with a pattern of temper tantrums in late childhood (ages 8–10) and to trace the continuities and consequences of this behavioral style across the subsequent 30 years of their lives. Life-course continuities in this behavioral style were found for both sexes. Men with histories of childhood tantrums experienced downward occupational mobility, erratic work lives, and were likely to divorce. Women with such histories married men with lower occupational status, were likely to divorce, and became ill-tempered mothers. It is proposed that maladaptive behaviors are sustained through the progressive accumulation of their own consequences (cumulative continuity) and by evoking maintaining responses from others during reciprocal social interaction (interactional continuity). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
56.
Changes in sleep after fetal preoptic (POA) tissue transplantation were studied in rats which had been made insomniac by a medial preoptic area (mPOA) lesion. Two days after the N-methyl D-aspartic acid (NMDA) lesion of the mPOA, fetal POA tissues (obtained from 14- to 17-day-old fetuses) were transplanted into the lesioned mPOA. Insomnia was less marked in these animals, as compared to nontransplanted lesioned rats, even on the 4th day after transplantation. The quantum of sleep nearly attained the prelesion level by the 20th day. Body weight also showed recovery after transplantation. Rectal temperature, which was increased by the lesion of the mPOA, remained unaltered even after the transplantation. These results suggest that the recovery of sleep and rectal temperature may follow different time courses. Surviving transplanted neurons were seen at the site of lesion on postmortem examination. Humoral interaction between the host and the transplant may be responsible for the early recovery of sleep, though the establishment of neural connections between the host and transplant might have contributed to the later recovery. This is the first study to show the recovery of sleep function in insomniac animals after fetal preoptic tissue transplantation. However, the specificity of the POA fetal tissue, in comparison with other neural tissues to promote sleep recovery, remains to be established.  相似文献   
57.
Clinical and epidemiologic studies have established that posttraumatic stress disorder (PTSD) is highly comorbid with other mental disorders. However, such studies have largely relied on adults' retrospective reports to ascertain comorbidity. The authors examined the developmental mental health histories of adults with PTSD using data on mental disorders assessed across the first 3 decades of life among members of the longitudinal Dunedin Multidisciplinary Health and Development Study; 100% of those diagnosed with past-year PTSD and 93.5% of those with lifetime PTSD at age 26 had met criteria for another mental disorder between ages 11 and 21. Most other mental disorders had first onsets by age 15. Of new cases of PTSD arising between ages 26 and 32, 96% had a prior mental disorder and 77% had been diagnosed by age 15. These data suggest PTSD almost always develops in the context of other mental disorders. Research on the etiology of PTSD may benefit from taking lifetime developmental patterns of comorbidity into consideration. Juvenile mental-disorder histories may help indicate which individuals are most likely to develop PTSD in populations at high risk of trauma exposure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
58.
This study examined the content validity of a juvenile psychopathy measure, the Childhood Psychopathy Scale (CPS; D. R. Lynam, 1997), based on a downward translation of an adult instrument, the Hare Psychopathy Checklist-Revised (PCL-R; R. D. Hare, 1991). The CPS was compared with two other indices of juvenile psychopathy: (a) an index derived from expert ratings and (b) an empirical index based on correlations with adult psychopathy. The 100 items of the Common Language Q-Sort (CLQ; A. Caspi et al., 1992) provided a common metric for the comparison. Psychopathy and personality were assessed at age 13 years with the mother-reported CPS and the CLQ. Psychopathy was assessed at age 24 years with the interviewer-rated Psychopathy Checklist: Screening Version (PCL:SV; S. D. Hart, D. N. Cox, & R. D. Hare, 1995). Data from over 250 participants of the middle sample of the Pittsburgh Youth Study were used to examine these relations. Item content analyses demonstrated considerable overlap among the three indices, indicating that the downward translation utilizes criteria similar to those of experts and the empirically-derived measure. In addition, these indices, even after removing overlapping items, demonstrated considerable convergence, also supporting the content validity of the downward translation. These results suggest that the downward translation method is adequate for understanding the juvenile psychopathy construct. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
59.
The well-documented relation between the phenotypes of low IQ and childhood antisocial behavior could be explained by either common genetic influences or environmental influences. These competing explanations were examined through use of the Environmental Risk Longitudinal Twin Study 1994-1995 cohort (Moffitt & the E-Risk Study Team, 2002) of 1,116 twin pairs and their families. Children's IQ was assessed via individual testing at age 5 years. Mothers and teachers reported on children's antisocial behavior at ages 5 and 7 years. Low IQ was related to antisocial behavior at age 5 years and predicted relatively higher antisocial behavior scores at age 7 years when antisocial behavior at age 5 years was controlled. This association was significantly stronger among boys than among girls. Genetic influences common to both phenotypes explained 100% of the low IQ-antisocial behavior relation in boys. Findings suggest that specific candidate genes and neurobiological processes should be tested in relation to both phenotypes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
60.
Using prospective data from the Dunedin Multidisciplinary Health and Development Study birth cohort, the authors found that adolescents with low self-esteem had poorer mental and physical health, worse economic prospects, and higher levels of criminal behavior during adulthood, compared with adolescents with high self-esteem. The long-term consequences of self-esteem could not be explained by adolescent depression, gender, or socioeconomic status. Moreover, the findings held when the outcome variables were assessed using objective measures and informant reports; therefore, the findings cannot be explained by shared method variance in self-report data. The findings suggest that low self-esteem during adolescence predicts negative real-world consequences during adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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