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排序方式: 共有686条查询结果,搜索用时 15 毫秒
81.
Antonio Paolozzi Manfredi Porfilio Douglas G. Currie Ronald F. Dantowitz 《Microgravity science and technology》2007,19(5-6):65-69
The objective of the Specular Point-like Quick Reference (SPQR) experiment was to evaluate the possibility of improving the resolution of ground-based telescopic imaging of manned spacecraft in orbit. The concept was to reduce image distortions due to atmospheric turbulence by evaluating the Point Spread Function (PSF) of a point-like light reference and processing the spacecraft image accordingly. The target spacecraft was the International Space Station (ISS) and the point-like reference was provided by a laser beam emitted by the ground station and reflected back to the telescope by a Cube Corner Reflector (CCR) mounted on an ISS window. The ultimate objective of the experiment was to demonstrate that it is possible to image spacecraft in Low Earth Orbit (LEO) with a resolution of 20 cm, which would have probably been sufficient to detect the damage which caused the Columbia disaster. The experiment was successfully performed from March to May 2005. The paper provides an overview of the SPQR experiment. 相似文献
82.
Rabbit corneal epithelial cells cultured in the presence of 3T3 feeder cells undergo biochemical differentiation, as evidenced by their initial expression of K5 and K14 keratins characteristic of basal keratinocytes, followed by the subsequent expression of K3 and K12 keratin markers of corneal epithelial differentiation. Previous data established that mutations of an Sp1 site in a DNA element, E, that contains overlapping Sp1 and AP-2 motifs reduce K3 gene promoter activity by 70% in transfection assays. We show here that Sp1 activates while AP-2 represses the K3 promoter. Although undifferentiated corneal epithelial basal cells express equal amounts of Sp1 and AP-2 DNA-binding activities, the differentiated cells down-regulate their Sp1 activity slightly but their AP-2 activity drastically, thus resulting in a six- to sevenfold increase in the Sp1/AP-2 ratio. This change coincides with the activation and suppression of the differentiation-related K3 gene and the basal cell-related K14 keratin gene, respectively. In addition, we show that polyamines, which are present in a high concentration in proliferating basal keratinocytes, can inhibit the binding of Sp1 to its cognate binding motif but not that of AP-2. These results suggest that the relatively low Sp1/AP-2 ratio as well as the polyamine-mediated inhibition of Sp1 binding to the E motif may account, in part, for the suppression of the K3 gene in corneal epithelial basal cells, while the elevated Sp1/AP-2 ratio may be involved in activating the K3 gene in differentiated corneal epithelial cells. Coupled with the previous demonstration that AP-2 activates the K14 gene in basal cells, the switch of the Sp1/AP-2 ratio during corneal epithelial differentiation may play a role in the reciprocal expression of the K3 and K14 genes in the basal and suprabasal cell layers. 相似文献
83.
RP Weissburg PW Berman JL Cleland D Eastman F Farina S Frie A Lim J Mordenti TT Nguyen MR Peterson 《Canadian Metallurgical Quarterly》1995,12(10):1439-1446
PURPOSE: The characterization of recombinant MN gp120/alum vaccine requires the study of the gp120-alum interaction for the successful formulation of an alum-based HIV-1 vaccine. METHODS: Several observations suggest that the gp120-alum interaction is weak, wherein buffer counterions such as phosphate, sulfate, bicarbonate may cause the desorption of gp120 from alum. Comparison of gp120 with other proteins using particle mobility measurements shows that the weak binding of gp120 to alum is not an anomaly. Serum and plasma also cause desorption of gp120 from alum with a half-life of only a few minutes, wherein this half-life may be faster than the in-vivo recruitment of antigen presenting cells to the site of immunization. RESULTS: Immunization of guinea pigs, rabbits and baboons with gp120 formulated in alum or saline demonstrated that alum provides adjuvant activity for gp120, particularly after early immunizations, but the adjuvant effect is attenuated after several boosts. CONCLUSIONS: These observations indicate that both the antigen and the adjuvant require optimization together. 相似文献
84.
85.
TT Tsong 《Canadian Metallurgical Quarterly》1991,44(24):13703-13710
86.
EM Conill CA Pieralisi MA Peres C Castilhos AB Ortiga TT Li S Nascimento 《Canadian Metallurgical Quarterly》1998,14(4):857-861
This study describes the 'Law Court' technique as applied to City Health Departments in the State of Santa Catarina, in dealing with the issue of obligations on the part of public officials. The project was the first part of a training course for public administrators held in 1997. The article presents the technique's components and results. Some 98% of the 156 participants had a positive opinion of the training course, considering it dynamic/participatory (31%), educational/stimulating reflection (27%), and realistic (24%). The technique fostered the discussion of the main subjects pertaining to the country's Unified Health System (SUS). Although all five juries acquitted the defendants, the issue of ethics was reported by 58% of the participants as the main prerequisite for a public administrator. 相似文献
87.
TT Kane M Gueye I Speizer S Pacque-Margolis D Baron 《Canadian Metallurgical Quarterly》1998,29(3):309-323
An integrated multimedia campaign featuring family planning messages saturated the 900,000-person city of Bamako, Mali, for three months during the spring of 1993. With traditional theater and music, family planning messages were repeatedly broadcast on radio and television that conveyed information about modern contraceptive methods, the need for male sexual responsibility, the health and economic advantages of family planning, the need for communication between spouses, and that Islam, the predominant faith of Mali, does not oppose family planning. A separate sample pretest-post-test quasi-experimental research design was used to evaluate the effects of the campaign and exposure to specific messages on changes in contraceptive knowledge, attitudes, and practice. Results indicate a high level of exposure to and agreement with the messages. A dramatic drop was found in the proportion of men and women who believe that Islam opposes family planning. Logistic regression results indicate that contraceptive knowledge and use and more favorable attitudes toward family planning are positively associated with intensity of exposure to the project interventions, after controlling for relevant variables. 相似文献
88.
JD McEvoy CE McVeigh JW Currie DG Kennedy WJ McCaughey 《Canadian Metallurgical Quarterly》1998,22(7):479-491
The synthetic androgen 19-nortestosterone (beta-NT) has been used illegally as a growth promoter in cattle production in the European Union. Elimination of beta-NT and its metabolites in plasma, urine and bile was studied in three cattle with cannulated gallbladders following intramuscular injection at a single site of 500 mg of the laurate ester (NTL) containing 300.5 mg beta-NT. Using enzyme immunoassay quantification, plasma Cmax of free beta-NT was 0.5 +/- 0.15 microgram/L (mean +/- SEM). Concentrations of free beta-NT in plasma were consistently greater than the assay limit of quantification (0.12 microgram/L) for 32.7 +/- 13.42 days. Mean residence time for the beta-NT in plasma was 68.5 +/- 20.75 days. Following sample preparation by immunoaffinity chromatography, high-resolution GC-MS was used to quantify beta-NT and alpha-NT in urine and bile. beta-NT was detected irregularly in urine from two of the three animals post injection. The principal metabolite present in the urine, alpha-NT, was detected for 160.3 +/- 22.67 days post injection. Cmax for alpha-NT in urine was 13.7 +/- 5.14 micrograms/L. Mean urinary AUC0-183 days for alpha-NT was 845.7 +/- 400.90 (microgram h)/L. In bile, alpha-NT was the only metabolite detected for 174.3 +/- 8.67 days post treatment. Cmax for alpha-NT in bile was 40.8 +/- 12.70 micrograms/L and mean biliary AUC0-183 days for alpha-NT was 1982.6 +/- 373.81 (microgram h)/L. Concentrations of alpha-NT in bile samples were greater than those in urine samples taken at the same time. The mean ratio of biliary:urinary AUC0-183 days was 3.0 +/- 0.72. It is concluded that bile is a superior fluid for detection of alpha-NT following injection of NTL, owing to the longer period during which residues may be detected after administration. 相似文献
89.
PE Young NJ Beasley DJ Houghton DJ Husband M Currie B Chislett AS Jones 《Canadian Metallurgical Quarterly》1998,23(6):528-532
A new short questionnaire to assess the quality of life of head and neck patients has been designed at the University of Liverpool Head and Neck Oncology Department. The questionnaire is short, simple and can be easily completed by a patient whilst in the waiting room before consultation. It is filled in 6 months after completion of treatment and shows very good correlation with the standard long exhaustive questionnaires that are difficult to complete on every patient in a busy National Health Service clinic. The University of Liverpool questionnaire provides a simple score from 0%-100% which should prove valuable in the assessment of quality of care and help with decisions regarding treatment options in head and neck cancer patients. 相似文献
90.