25,180 research outputs found
Lymphoid cell kinetics under continuous low dose-rate gamma irradiation: A comparison study
The mechanism of cell proliferation is studied in the lymphoid tissue of the mouse spleen under the stress of continuous irradiation at a dose-rate of 10 roentgens per day for 105 days. Autoradiography and specific labeling with tritiated thymidine were utilized. It was found that at least four compensatory mechanisms maintained a near-steady state of cellular growth: (1) an increase in the proportion of PAS-positive cells which stimulate mitotic activity, (2) maturation arrest of proliferating and differentiating cells which tend to replenish the cells damaged or destroyed by irradiation, (3) an increase in the proportion of cells proliferating, and (4) an increase in the proportion of precursor cells. The results are compared to previous findings observed in the thymus
The effect of continuous low dose-rate gamma irradiation on cell population kinetics of lymphoid tissue
Cellular response and cell population kinetics were studied during lymphopoiesis in the thymus of the mouse under continuous gamma irradiation using autoradiographic techniques and specific labeling with tritiated thymidine. On the basis of tissue weights, it is concluded that the response of both the thymus and spleen to continuous low dose-rate irradiation is multiphasic. That is, alternating periods of steady state growth, followed by collapse, which in turn is followed by another period of homeostasis. Since there are two populations of lymphocytes - short lived and long-lived, it may be that different phases of steady state growth are mediated by different lymphocytes. The spleen is affected to a greater extent with shorter periods of steady-state growth than exhibited by the thymus
Lymphoid cell kinetics under continuous low dose-rate gamma irradiation: A comparison study
A comparison study was conducted of the effects of continuous low dose-rate gamma irradiation on cell population kinetics of lymphoid tissue (white pulp) of the mouse spleen with findings as they relate to the mouse thymus. Experimental techniques employed included autoradiography and specific labeling with tritiated thymidine (TdR-(h-3)). The problem studied involved the mechanism of cell proliferation of lymphoid tissue of the mouse spleen and thymus under the stress of continuous irradiation at a dose rate of 10 roentgens (R) per day for 105 days (15 weeks). The aim was to determine whether or not a steady state or near-steady state of cell population could be established for this period of time, and what compensatory mechanisms of cell population were involved
Water resource records of the Econfina Creek Basin area, Florida
The Econfina Creek basin area in northwestern Florida, which includes Bay
County, southeastern Washiigton County, and parts of Calhoun, Gulf, and
Jackson counties is shown in figure 1. The basin has an abundant supply of
ground water and surface water of good quality. This determination is based on
a three-year investigation of the water resources of the basin by the U. S.
Geological Survey in cooperation with the Division of Geology, Florida Board of
Conservation, during the period from October 1961 through June 1964. The
purpose of this report is to assemble the basic data collected during this
investigation for those persons interested in water development or management
in this basin.
(Document has 131 pages.
Flow field computations for blunt bodies in planetary environments
Numerical analysis on flow distribution around hypersonic blunt body in planetary atmospher
Prevalence and causes of blindness and visual impairment in Muyuka: a rural health district in South West Province, Cameroon.
AIM: To estimate the prevalence and causes of blindness and visual impairment in the population aged 40 years and over in Muyuka, a rural district in the South West Province of Cameroon. METHODS: A multistage cluster random sampling methodology was used to select 20 clusters of 100 people each. In each cluster households were randomly selected and all eligible people had their visual acuity (VA) measured by an ophthalmic nurse. Those with VA <6/18 were examined by an ophthalmologist. RESULTS: 1787 people were examined (response rate 89.3%). The prevalence of binocular blindness was 1.6% (95% CI: 0.8% to 2.4%), 2.2% (1.% to 3.1%) for binocular severe visual impairment, and 6.4% (5.0% to 7.8%) for binocular visual impairment. Cataract was the main cause of blindness (62.1%), severe visual impairment (65.0%), and visual impairment (40.0%). Refractive error was an important cause of severe visual impairment (15.0%) and visual impairment (22.5%). The cataract surgical coverage for people was 55% at the <3/60 level and 33% at the <6/60 level. 64.3% of eyes operated for cataract had poor visual outcome (presenting VA<6/60). CONCLUSIONS: Strategies should be developed to make cataract services affordable and accessible to the population in the rural areas. There is an urgent need to improve the outcome of cataract surgery. Refractive error services should be provided at the community level
Radiology Education and the Quality of Care: Radiation Dose
The purpose of this quantitative, quasi-experimental study was to analyze whether the education of radiology personnel mandated by the American Registry of Radiologic Technologists (ARRT) affects the quality of care delivered to radiology patients. One area of radiology quality of care was focused on the findings presented in this study: radiation dosage. Three groups of study participants were used. The participants were chosen and divided into groups based on their radiology background, non-radiology medical background, or lack of medical background. All study participants were required to complete an assessment asking participants what radiation dosage and shields they would use for a standard set of radiographic examinations. A training video was shown to those participants with no radiology background prior to the assessment. The data provided by each group was compared to determine similarities and variances between the groups and ANOVA calculations were completed. Differences were found between the assessments completed by members of all three groups. The results support the perception that ARRT-mandated education does affect radiation dosage chosen in the care of radiology patients
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Implementation of the Licensing Act 2003: a national survey
The Licensing Act 2003 came into force in November 2005 and transferred responsibility for alcohol licensing to Local Authorities. This reports the findings of a nation wide survey of 225 (63%) local authority chairs of licensing committees/senior members of licensing teams in England evaluating the short-term impact of the Act
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