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The Borexino experiment, for the study of solar neutrino physics, requires radiopurity at the level of 5 × 10−16 g/g 238U equivalent (or 6 × 10−9 Bq/kg) on a detector mass of many tons of scintillator. Feasibility studies are performed in a counting test facility now operating at LNGS, which consists of 4 t of liquid scintillator viewed by 100 photomultipliers and shielded by 100 t of water. The accomplishment of this goal requires the shielding liquid, water, to be at the 10−13 g/g contamination level (1.2 × 10−6 Bq/kg) or better. This paper describes the water purification system; it consists of a combination of several purification processes to remove particulate, radioactive ions, dissolved gases and other impurities. Residual contaminations are measured by analytical or direct-counting techniques. For radon measurement, particularly challenging at this low activity levels, a low background counting method has been developed.  相似文献   
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The purpose of this study was to determine the etiologic factors of denture stomatitis. Fifteen subjects with clinical evidence of localized simple denture stomatitis, fifteen subjects without clinical signs of denture stomatitis, and forty-five subjects with clinical evidence of generalized simple denture stomatitis were investigated clinically and mycologically. Subjects were evaluated according to age, sex, duration of denture usage, smoking habits, frequency of denture brushing, overnight denture wearing, pH level of saliva and degree of candidal colonization and candidal formation. Salivary samples and swabs were taken from the palate and the mucosal surfaces of the dentures investigated mycologically in order to identify the yeast colonies. Smears were taken from the palate and investigated in order to identify candidal formation. No statistically significant relationship was found between denture stomatitis and age, sex, duration of denture usage, frequency of denture brushing, overnight denture wearing or pH level of saliva. There was however, a statistically significant relationship between denture stomatitis and denture hygiene, smoking habits, candidal colonization and candidal formation.  相似文献   
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PURPOSE: We determined the impact of preexisting co-morbidities on survival of men with clinical stages T1b and T2NXM0 prostate cancer treated with surgery or radiation therapy. MATERIALS AND METHODS: A weighted co-morbidity score was determined for 276 consecutive men treated with surgery (138) or radiation therapy (138) at a Veterans Affairs medical center and was correlated with actuarial freedom from death due to co-morbid disease. RESULTS: After a median potential followup of 7.0 years 91 patients (33%) died of co-morbid disease and 20 (7%) died of cancer related causes. There were highly significant correlations between actuarial survival and weighted co-morbidity (p < 0.000001), and the 10-year actuarial survivals in men with no or severe co-morbidities were 66 and 9%, respectively. Associations between patient age and co-morbidity score were highly significant (p < 0.0001). The age adjusted risk of co-morbid death was 5.7 times greater in men with severe compared to no co-morbidities. There were also significant correlations between actuarial survival and weighted co-morbidity among patients treated with surgery (p = 0.02) and radiation therapy (p = 0.0002). Patient age and severity of co-morbidities were significantly greater among men treated with radiation therapy compared to surgery, and age adjusted risk of co-morbid death among men with a co-morbidity score of 1 was 3.8 times greater among men treated with radiation therapy (p = 0.025). CONCLUSIONS: Cancer related deaths are unusual within 5 to 10 years after surgery or radiation therapy in men with stages T1b and 2 prostate cancer. The risk of death during this interval is directly related to the severity of co-morbid conditions, which should be factored in an individual when assessing the advisability of therapeutic intervention. Since patient co-morbidities impact all cause survival, quantitative assessment of co-morbidities using validated instruments offers a method to control partially for the variabilities of health status among men receiving different treatments for localized prostate cancer.  相似文献   
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Clinical characteristics associated with bacillary angiomatosis and bacillary peliosis (BAP) in patients with human immunodeficiency virus (HIV) infection were evaluated in a case-control study; 42 case-patients and 84 controls were matched by clinical care institution. Case-patients presented with fever (temperature, > 37.8 degrees C; 93%), a median CD4 lymphocyte count of 21/mm3, cutaneous or subcutaneous vascular lesions (55%), lymphadenopathy (21%), and/or abdominal symptoms (24%). Many case-patients experienced long delays between medical evaluation and diagnosis of BAP (median, 4 weeks; range, 1 day to 24 months). Case-patients were more likely than controls to have fever, lymphadenopathy, hepatomegaly, splenomegaly, a low CD4 lymphocyte count, anemia, or an elevated serum level of alkaline phosphatase (AP) (P < .001). In multivariate analysis, a CD4 lymphocyte count of < 200/mm3 (matched odds ratio [OR], 9.9; P < .09), anemia reflected by a hematocrit value of < 0.36 (OR, 19.7; P < .04), and an elevated AP level of > or = 2.6 mukat/L (OR, 23.9; P < .05) remained associated with disease after therapy with zidovudine was controlled for. BAP should be considered an AIDS-defining opportunistic infection and should be included in the differential diagnosis for febrile, HIV-infected patients with cutaneous or osteolytic lesions, lymphadenopathy, abdominal symptoms, anemia, or an elevated serum level of AP.  相似文献   
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OBJECTIVE: To describe a simple injection apparatus and method for performing intracytoplasmic sperm injection in a clinical IVF program. DESIGN: A prospective clinical trial of intracytoplasmic sperm injection. SETTING: A private office-based fertility program. PATIENTS: Five couples undergoing IVF-ET with intracytoplasmic sperm injection as a treatment for male factor infertility. INTERVENTIONS: Intracytoplasmic sperm injection was performed at room temperature (23.5 to 24.5 degrees C) in a simple zwitterion-buffered medium. MAIN OUTCOME MEASURES: Fertilization rates, cleavage rates, clinical pregnancy rates, implantation rates. RESULTS: Intracytoplasmic sperm injection was performed on 44 fresh oocytes from five patients. Twenty-three oocytes fertilized (52.3%) and 22 zygotes cleaved (95.7%). Three of five patients became pregnant (60%), resulting in the live birth of one normal male infant, one continuing singleton pregnancy, and one continuing twin gestation (46XX, 46XY). The implantation rate was 23.5%. CONCLUSION: Intracytoplasmic sperm injection can be performed successfully in a simple medium at room temperature using commercially available microtools.  相似文献   
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