2 resultados para Tritium.

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo


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Stable isotopes, tritium, radium isotopes, radon, trace elements and nutrients data were collected during two sampling campaigns in the Ubatuba coastal area (south-eastern Brazil) with the aim of investigating submarine groundwater discharge (SGD) in the region. The isotopic composition (delta D, delta(18)O, (3)H) of submarine waters was characterised by significant variability and heavy isotope enrichment. The stable isotopes and tritium data showed good separation of groundwater and seawater groups. The contribution of groundwater in submarine waters varied from a few % to 17%. Spatial distribution of (222)Rn activity concentration in surface seawater revealed changes between 50 and 200 Bq m(-3) which were in opposite relationship with observed salinities. Time series measurements of (222)Rn activity concentration in Flamengo Bay (from 1 to 5 kBq m(-3)), obtained by in situ underwater gamma-spectrometry showed a negative correlation between the (222)Rn activity concentration and tide/salinity. This may be caused by sea level changes as tide effects induce variations of hydraulic gradients, which increase (222)Rn concentration during lower sea level, and opposite, during high tides where the (222)Rn activity concentration is smaller. The estimated SGD fluxes varied during 22-26 November between 8 and 40 cm d(-1), with an average value of 21 cm d(-1) (the unit is cm(3)/cm(2) per day). The radium isotopes and nutrient data showed scattered distributions with offshore distance and salinity. which implies that in a complex coast with many small bays and islands, the area has been influenced by local currents and groundwater-seawater mixing. SGD in the Ubatuba area is fed by coastal contaminated groundwater and re-circulated seawater (with small admixtures of groundwater). which claims for potential environmental concern with implications on the management of freshwater resources in the region. (C) 2007 Elsevier Ltd. All rights reserved.

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Objective: - To develop and test a practical clinical method to assess frailty in nursing homes; - To investigate the relationship between cognitive status of the elderly and the balance between water compartments of their body composition. Design and subjects: Cross-sectional study, conducted at two nursing homes in Boston-MA. Methods: Body mass and height (Ht) were evaluated to calculate BMI (body mass index, in Kg/m(2)). The cognitive decline was evaluated based on the scores obtained from the Mini-Mental State Examination (MMSE); The extracellular to total body water ratio (ECW/TBW) was calculated after the analysis of TBW from deuterium and tritium dilution and ECW from bromide dilution. Single-frequency BIA analysis data were investigated for resistance (R) and reactance (Xc), plotted in an R/Ht Xc/Ht graph (vectorial analysis-BIVA). The BIVA results of nursing home residents were compared against the data obtained from the NHANES Ill study. TBW and ECW values were compared with a group of free-living elderly volunteers. Results: The ECW/TBW was significantly higher in nursing home residents than in the free-living individuals. BIVA analysis showed significantly higher Xc/Ht values in the reference subjects. The MMSE did not present a significant correlation with ECW/TBW for either gender. Conclusion: We proposed the ECW/TBW ratio and BIVA as surrogate methods for the clinical assessment of frailty. We tested successfully both approaches with nursing home patients and free-living volunteers and compared them to a national data base. The advent of new, portable instruments will enable field tests to further validate our proposed "Frailty Factor" in future studies. We found no correlation between frailty and cognitive decline in the nursing home.