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61.
When a person moves through the world, the associated visual displacement of the environment in the opposite direction is not usually seen as external movement but rather as a changing view of a stable world. We measured the amount of visual motion that can be tolerated as compatible with the perception of moving within a stable world during active, sinusoidal, translational and rotational head movement. Head movements were monitored by means of a low-latency, mechanical head tracker and the information was used to update a helmet-mounted visual display. A variable gain was introduced between the head tracker and the display. Ten subjects adjusted this gain until the visual display appeared stable during sinusoidal yaw, pitch and roll head rotations and naso-occipital, inter-aural and dorso-ventral translations at 0.5 Hz. Each head movement was tested with movement either orthogonal to or parallel with gravity. A wide spread of gains was accepted as stable (0.8 to 1.4 for rotation and 1.1 to 1.8 for translation). The gain most likely to be perceived as stable was greater than that required by the geometry (1.2 for rotation; 1.4 for translation). For rotational motion, the mean gains were the same for all axes. For translation there was no effect of whether the movement was inter-aural (mean gain 1.6) or dorso-ventral (mean gain 1.5) and no effect of the relative orientation of the translation direction relative to gravity. However translation in the naso-occipital direction was associated with more closely veridical settings (mean gain 1.1) and narrower standard deviations than in other directions. These findings are discussed in terms of visual and non-visual contributions to the perception of an earth-stable environment during active head movement.  相似文献   
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Weill-Marchesani syndrome (WMS) is a rare condition characterized by short stature, brachydactyly, joint stiffness, and characteristic eye abnormalities including microspherophakia, ectopia of lens, severe myopia, and glaucoma. Both autosomal recessive (AR) and autosomal dominant (AD) modes of inheritance have been described for WMS. A locus for AR WMS has recently been mapped to chromosome 19p13.3-p13.2 while mutation within the fibrillin-1 gene (15q21.1) was found in one AD WMS family. In order to answer the question of whether or not genetic heterogeneity could be related to a clinical heterogeneity, we reviewed 128 WMS patients from the literature (including 57 AR, 50 AD, and 21 sporadic cases), with a particular attention to clinical features. Statistical analyses using Fischer exact test were used to compare the proportions of 12 clinical parameters between AR and AD patients. There was no significant difference between both groups for myopia, glaucoma, cataract, short stature, brachydactyly, thick skin, muscular build, and mental retardation. Significant results were found for microspherophakia (94% in AR, 74% in AD, Fischer 0.007), ectopia lentis (64% in AR, 84% in AD, Fischer 0.016), joint limitations (49% in AR, 77% in AD, Fischer 0.010), and cardiac anomalies (39% in AR, 13% in AD, Fischer 0.004). Nevertheless, we failed to distinguish AR from AD inheritance in individual cases. These results support the clinical homogeneity but the genetic heterogeneity of WMS.  相似文献   
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The primary interest of our laboratory is understanding how the signals that a T cell receives influence its behavior during an immune response. Recently, we have focused our attention on the examination of T cell responses at an individual cell level. This article outlines our approach, presents our initial findings, and discusses the implications of these findings relative to our current models of T cell activation.  相似文献   
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The self-perceptions of children with attention-deficit/hyperactivity disorder (ADHD; n = 487) were compared with those of children in a local normative comparison group (n = 287), relative to teacher- and parent-rated perceptions of their competence. Children were participants in the ongoing follow-up portion of the Multimodal Treatment Study of Children with ADHD. Children with ADHD were much more likely than comparison children to overestimate their competence relative to adult report, regardless of who was used as the criterion rater (teacher, mother, or father). Examination by comorbidity subgroups revealed that children with ADHD inflated their self-perceptions the most in domains of greatest deficit. Gender effects also are reported.  相似文献   
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The aim of this study was to determine, by transmission electron microscopy, the differentiation features of 21 human malignant mesothelioma cell lines (HMCLs) established from 13 specimens of 12 confirmed human malignant mesotheliomas, and of tumours induced in nude mice injected with 16 HMCLs. Fifty per cent of HMCLs showed typical mesothelial differentiation (long and slender microvilli, desmosomes, perinuclear intermediate filaments); 29 per cent did not show differentiation; and the remainder were poorly differentiated. Three human tumour specimens gave several different HMCLs; the cell lines obtained from a given tumour exhibited variable mesothelial differentiation. Eleven HMCLs were compared with the native tumour. Four were similar to the tumour and seven were less well differentiated, in most cases in relation to their microvilli. With six HMCLs, tumours induced in nude mice were less well differentiated than the corresponding cell lines, whereas with four HMCLs, tumours were equally or better differentiated. However, in most nude mice tumours, typical mesothelial microvilli were present. These results show that cell lines established from malignant mesothelioma may exhibit dedifferentiated features. However, while the variability in ultrastructural differentiation may result from the culture microenvironment, it could also be related to the state of differentiation, of the native tumour sample and to tumour cell heterogeneity.  相似文献   
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