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Thin Film Thermoelectric Metal–Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity 下载免费PDF全文
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Castro M. Foster R.S. Gunn K. Roberts E.B. 《Engineering Management, IEEE Transactions on》2003,50(3):297-306
The virtual agency concept is now used within the United States Government as an alliance approach to manage large research and development (R&D) processes across departments. This paper examines the history of the virtual agency concept and its important characteristics. The paper identifies the potential benefits and associated risks involved in managing R&D within a virtual agency. Three cases are examined where the virtual agency concept has been applied to R&D programs: the High Performance Computing and Communications initiative, the Next Generation Internet, and the Partnership for a New Generation of Vehicles. The case studies indicate that the R&D process is attempting to balance formal process controls with the agility to adapt rapidly to new research opportunities. Virtual agencies can be used to improve organizational efficiency, improve knowledge transfer, increase interoperability through standards, provide better alignment of agency missions with national policy, and introduce increased flexibility into the R&D process. At the same time, the virtual agency concept has major risks including inefficiencies due to organizational complexity, the danger of collective myopia, the problem of adopting standards too early, the difficulty of reaching objectives in a loose organizational structure, and the problem of properly balancing the tension between agency mission objectives and national policy agendas. 相似文献
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Transforming growth factor-alpha (TGF-alpha) is a growth-regulatory peptide found in a wide range of embryonic and adult tissues. TGF-alpha is produced by keratinocytes and has been reported to be overexpressed in several epidermal diseases, including middle ear cholesteatoma. This report describes ear pathology in the waved-1 mutant mouse, which is severely deficient in TGF-alpha. Morphologic changes of the external and middle ear were studied histologically in waved-1 mutants 2 weeks to 6.5 months of age. Abnormalities found in the mutants included epidermal hyperplasia of the external ear canal (EAC) and tympanic membrane (TM) and enlargement of specialized sebaceous glands adjacent to the cartilaginous EAC. Sebum and desquamated keratin progressively accumulated within the EAC, displacing the TM into the middle ear. These changes appear similar to those occurring in Mongolian gerbils, which are known to develop cholesteatoma. The alterations found in waved-1 mutants are discussed in relation to the possible involvement of TGF-alpha in cholesteatoma pathogenesis. 相似文献
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Apolipoprotein E plays a central role in clearance of lipoprotein remnants by serving as a ligand for low-density lipoprotein and apolipoprotein E receptors. Three common alleles (apolipoprotein E(2), E(3) and E(4)) give rise to six phenotypes. Apolipoprotein E(3) is the ancestral form. Common apolipoprotein E isoforms derive from nucleotide substitutions in codons 112 and 158. Resulting cysteine-arginine substitutions cause differences in: affinities for low-density lipoprotein and apolipoprotein E receptors, low-density lipoprotein receptor activities, distribution of apolipoprotein E among lipoproteins, low-density lipoprotein formation rate, and cholesterol absorption. Accompanying changes in triglycerides, cholesterol and low-density lipoprotein may promote atherosclerosis development. Over 90% of patients with familial dysbetalipoproteinaemia have apolipoprotein E(2)/E(2). Apolipoprotein E(4) may promote atherosclerosis by its low-density lipoprotein raising effect. Establishment of apolipoprotein E isoforms may be important for patients with diabetes mellitus and several non-atherosclerotic diseases. Apolipoprotein E phenotyping exploits differences in isoelectric points. Isoelectric focusing uses gels that contain pH 4-7 ampholytes and urea. Serum is directly applied, or prepurified by delipidation, lipoprotein precipitation or dialysation. Isoelectric focusing is followed by immunofixation/protein staining. Another approach is electro- or diffusion blotting, followed by protein staining or immunological detection with anti-apolipoprotein E antibodies and an enzyme-conjugated second antibody. Apolipoprotein E genotyping demonstrates underlying point mutations. Analyses of polymerase chain reaction products are done by allele-specific oligonucleotide probes, restriction fragment length polymorphism, single-stranded conformational polymorphism, the primer-guided nucleotide incorporation assay, or denaturating gradient gel electrophoresis. Detection with primers that either or not initiate amplification is performed with the amplification refractory mutation system. Disparities between phenotyping and genotyping may derive from isoelectric focusing methods that do not adequately separate apolipoprotein E posttranslational variants, storage artifacts or faint isoelectric focusing bands. 相似文献
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DA O'Farrell HM Ridha P Keenan FW McManus M Stephens 《Canadian Metallurgical Quarterly》1997,28(5-6):377-379
Roller blading is a new and increasingly popular leisure activity in many countries. We reviewed 110 consecutive patients with roller-blade injuries between 1 January and 30 June 1996. The patients ranged from 4 to 14 years in age (mean 6.5 years). Eighty-three (75.4%) sustained injuries to the upper limb and 27 (24.5%) injured the lower limb. Fifty-six patients, were girls and 54 were boys. Of the 110 patients, 79 (72.7%) sustained fractures, 28 (25.4%) soft tissue injuries and 3 (2.7%) dislocations. Eighty-three (75.4%) of the patients wore no protective equipment on the limbs. Four months following injury 103 (93.6%) patients were fully recovered. The mean duration of school absence was 3 days. Subsequently 101 children returned to using roller-blades following injury. Seventy-three (66.3%) of these now use protective equipment. We found that injuries were unrelated to age or duration of roller-blading experience or to the brand-name of roller blades used, and that most of our patients wore no protective equipment at the time of injury. 相似文献
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Within the realm of oncology nursing, research has been an integral part in its development as a specialty practice. Yet despite the growing volume of published nursing research studies, little is known about how nurses working in oncology care settings perceive research. Therefore, the purposes of this study were to examine clinical oncology nurses' perceptions of research and to determine factors influencing their perceptions. Two hundred and eighty-three registered nurses providing cancer care to patients in 40 health care agencies across northern Ontario participated in the survey. Data were collected using a questionnaire developed by Alcock and colleagues (1990) which addressed nurses' perceived value of research, their role, interest and experience in research as well as the research climate of the agency. The findings showed that respondents valued nursing research and perceived a research role for staff nurses. However, the respondents did not perceive strong administrative or collegial support for nurses' involvement in research activities. In addition, the study results indicated that the clinical oncology nurses' perceptions of research were influenced by educational preparation. 相似文献
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DA Puleo 《Canadian Metallurgical Quarterly》1997,173(1):93-101
Murine Leydig (TM3) and Sertoli (TM4) cell lines were studied as nonprofessional antigen-presenting cells using the antigen model of human choriogonadotropin (hCG alpha/beta) and specific T-cell hybridomas. Both cell lines were treated with IFN-gamma to induce I-A(d) and I-E(d) molecules expression. Only the TM3 cell line, which expressed MHC-class II molecules upon IFN-gamma stimulation, was able to uptake, process, and present the human choriogonadotropin beta subunit to related T-cell hybridomas. Interestingly, the TM3 cell line was incapable of presenting the human choriogonadotropin alpha subunit, the presentation of which, by classical APC, is highly efficient. Using T-cell hybridomas directed against the immunogenic regions of hCG alpha/beta previously described in BALB/c mice, we showed that the TM3 cell line generated a narrower peptide repertoire than classical APC (i.e., B cells, macrophages, and dendritic cells). This experimental system suggests that Leydig cells could initiate, in vivo, an autoimmune process directed against gonadal tissues. In particular, such a mechanism has been evoked in experimental autoimmune orchitis. 相似文献