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51.
In April and May 1996, two cases of PDA ligation were performed firstly in Turkey by the method of video assisted thoracoscopic surgery (VATS) in Dokuz Eylül Medical Faculty, Thoracic and Cardiovascular Surgery Department. There was not any complication in these patients in the postoperative period and they were discharged on the second day in symptom-free condition by the detection of closed ductus in their echocardiographic examination. Between February 1993 and October 1996, a total of 46 patients have undergone interventional application by VATS. While in six of these patients the procedure could not be manipulated because of massive pleural fibrosis, there was no mortality or morbidity among the patients, and they were discharged on average on the second day. The ratio of complications, such as bleeding, air leak, arrhythmia and empyema are so low in these operations, and hospital stay, with return to work time are shorter than with the open technique.  相似文献   
52.
We report the case of a 15-year-old previously thalassemic girl who, 15 months after allogeneic BMT, developed HBeAg-negative hepatitis B (variant with mu-1896). In the absence of another route of transmission, HBV reactivation is postulated. The time of emergence of the HBV variant (with mu-1896) is probably related to the development of anti-HBe immunity. This mutant strain is associated with fulminant hepatitis. The patient achieved complete remission and HBV eradication despite having moderate GVHD and receiving immunosuppressive therapy.  相似文献   
53.
Postnatal rats at 7 and 21 days of age were subjected to unilateral hypoxia-ischemia (H/I) by right carotid artery ligation followed by 1.5 to 2 hours of hypoxia (8% oxygen). Brains were frozen at specific intervals of recovery from 0 to 24 hours. Western blots of samples of right and left forebrain were immunodeveloped with a monoclonal antibody specific for ubiquitin, RHUb1. An elevation of ubiquitin conjugate levels in the right compared with the left forebrain of 7-day-old animals was detectable immediately following H/I and increased by close to 60% of control level within 1 hour of recovery. The conjugate immunoreactivity remained at this level for 6 hours but had declined to control levels by 24 hours of recovery. No such increase was observed in response to hypoxia alone. Similar changes were observed in samples from the 21-day-old rat brain. However, the elevation of ubiquitin conjugate levels was of slower onset and persisted longer than observed for the 7-day-old animals. Immunocytochemical studies of brain fixed by immersion in formaldehyde/acetone/methanol showed that ubiquitin-like immunoreactivity was increased in the right, but not left, cerebral cortex and hippocampus of animals subjected to H/I. The data suggest that elevated ubiquitination may represent a neuroprotective response to H/I.  相似文献   
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Computer-mediated conferencing has been adopted, particularly for purposes of online course provision, as a method that can deliver community. Widespread interest in a communities-of-practice approach within both informal and formal learning has strengthened perceptions of the value of creating a community online. A case study of asynchronous computer conferencing for the purposes of leadership development in schools is the focus for a study of the features and the discursive quality of the online interaction that occurred. Two analytical approaches are used: discourse analysis and social network analysis. These highlighted different aspects of the case, in terms of the role of peers versus the expert moderator (or 'hotseat guest'), the extent of readership versus contribution and the tone and content of the discussion. Evidence that contributors were learning from the interaction was identified and strong links with place-based communities of practice were also evident. Nevertheless, the online interaction could not be said to constitute a community or to be evidently developing in that direction. Its features as a network, where weak links were key to a sharing and knowledge-construction process, were more salient. Networks offer the potential for weak connections that have a particular value for connecting across dispersed practitioners and potentially bridging between communities of practice and other forms of organisation and groupings.  相似文献   
56.
The residence times of solids flowing through a fluidized bed dryer exhibit dispersion about the mean. In this paper, expressions for the probability density functions of solids moisture content in the various stages of a multi-stage dryer are derived. A simple recurrence relationship for the moments of the distribution is also presented. The analysis is applied to the drying of cereal grains, and it is shown that the degree of drying increases with the number of stages in the dryer. Probability density functions of the moisture content are presented.  相似文献   
57.
Understanding the effects of allelopathic plant chemicals on soil microorganisms is critical to understanding their ecological roles and importance in exotic plant invasion. Centaurea stoebe Lam. (spotted knapweed), an aggressive invasive weed in North America, secretes a racemic mixture of (±)-catechin as a root exudate. This enantiomeric, polyphenolic compound has been reported to have allelopathic effects on surrounding flora and microflora. To better understand how catechin affects microbial communities in the root zone of spotted knapweed, we assessed its impact on the total culturable bacterial component and numerous individual bacterial populations from Romanian (native range) and Montana (invaded range) soils. Catechin suppressed total culturable count numbers from the bacterial community and inhibited growth of some, but not all, soil bacterial populations tested. The native soil bacterial community was significantly more resistant to inhibitory effects of catechin than either the invaded or non-invaded soils. We further show that the inhibitory effect of catechin on nine different soil bacterial strains from seven genera was reversible, demonstrating that it acts via a bacteriostatic rather than bactericidal mechanism. These findings suggest that catechin might affect bacterial community composition and activity in the root zone.  相似文献   
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59.
We fabricate freely suspended nanosheets of molybdenum disulphide (MoS2) which are characterized by quantitative optical microscopy and high-resolution friction force microscopy. We study the elastic deformation of freely suspended nanosheets of MoS2 using an atomic force microscope. The Young''s modulus and the initial pre-tension of the nanosheets are determined by performing a nanoscopic version of a bending test experiment. MoS2 sheets show high elasticity and an extremely high Young''s modulus (0.30 TPa, 50% larger than steel). These results make them a potential alternative to graphene in applications requiring flexible semiconductor materials.PACS, 73.61.Le, other inorganic semiconductors, 68.65.Ac, multilayers, 62.20.de, elastic moduli, 81.40.Jj, elasticity and anelasticity, stress-strain relations.  相似文献   
60.
Relative potencies and combination effects of steroidal estrogens in fish   总被引:1,自引:0,他引:1  
The natural steroids estradiol-17beta (E2) and estrone (E1) and the synthetic steroid ethynylestradiol-17alpha (EE2) have frequently been measured in waters receiving domestic effluents. All of these steroids bind to the estrogen receptor(s) and have been shown to elicit a range of estrogenic responses in fish at environmentally relevant concentrations. At present, however, no relative potency estimates have been derived for either the individual steroidal estrogens or their mixtures in vivo. In this study the estrogenic activity of E2, E1, and EE2, and the combination effects of a mixture of E2 and EE2 (equi-potent fixed-ratio mixture), were assessed using vitellogenin induction in a 14-day in vivo juvenile rainbow trout screening assay. Median effective concentrations, relative to E2, for induction of vitellogenin were determined from the concentration-response curves and the relative estrogenic potencies of each of the test chemicals calculated. Median effective concentrations were between 19 and 26 ng L(-1) for E2, 60 ng L(-1) for E1, and between 0.95 and 1.8 ng L(-1) for EE2, implying that EE2 was approximately 11 to 27 times more potent than E2, while E2 was 2.3 to 3.2 times more potent than E1. The median effective concentration, relative to E2, for the binary mixture of E2 and EE2 was 15 ng L(-1) (comprising 14.4 ng L(-1) E2 and 0.6 ng L(-1) EE2). Using the model of concentration addition it was shown that this activity of the binary mixture could be predicted from the activity of the individual chemicals. The ability of each individual steroid to contribute to the overall effect of a mixture, even at individual no-effect concentrations, combined with the high estrogenic potency of the steroids, particularly the synthetic steroid EE2, emphasizes the need to consider the total estrogenic load of these chemicals in our waterways.  相似文献   
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