Multielement analysis of natural waters by neutron activation,group chemical separations,and gamma-ray spectrometric techniques

A multielement analytical technique of thermal neutron activation of frozen water samples has been developed and applied to the studies of natural waters. A rapid group chemical separation utilizing ion exchange resins and a precipitation step to reduce ²⁴Na and 42K interferences, followed by γ-ray analysis of the fractions with Ge (Li) and multiparameter NaI (TI) systems, permits the simultaneous measurement of a large number of trace constituents. Samples of river water, rain water, processed sewage water and Greenland ice were analyzed for 19 trace elements — Ag, As, Br, Cl, Co, Cs, Cr, Cu, Fe, Hg, K, Mn, Na, Rb, Sb, Se, Se, U, and Zn. These data have been used in studies of trace element concentration factors in aquatic biota, precipitation scavenging processes, and environmental pollution.     

The End of the Nuclear Era: Nuclear Decommissioning and Its Economic Impacts on U.S. Counties

Between 1957 and 1990, nearly 100 nuclear reactors were constructed throughout the U.S., and nuclear power currently accounts for 20 percent of electricity production nationwide. Nuclear plants are often constructed in small communities for which they constitute a large source of employment and income. To date, 24 nuclear reactors have undergone decommissioning, and more are expected in the future, particularly as nuclear reactors age and face increasingly strict regulations. This paper examines the effects of nuclear decommissioning over time at the county‐level on measures of employment, income, and population using difference‐in‐differences regression and propensity score matching. Panel data are obtained from the U.S. Census Bureau, and cover the years 1975–2014. The analysis finds that nuclear decommissioning is associated with positive and statistically significant increases in employment and per capita income over time. Results suggest that nuclear decommissioning may actually be a positive force in regional economic development, and concludes with limitations of the approach and implications for future research. As an emerging area of research, this paper is meant to build on previous work, as well as to provide a basis for further discussion and debate on the economic future of nuclear host communities and regional economies.     

Correlation of endothal and fluorescent dye concentrations following concurrent application to tidal canals

Herbicide residue samples are expensive and time-consuming to collect and analyze. The potential for using ‘Rhodamine WT’ to simulate endothal dissipation in moving water was tested in the weed-infested Three Sisters tidal canals (Citrus Co., FL). Concurrent applications were made using a variety of application techniques. Significant correlations between dye and endothal concentrations were found in each treatment, indicating that ‘Rhodamine WT’ concentrations can be used to predict endothal movement and concentrations. The ratios of endothal:dye half-lives were similar (0.2, 0.25, 0.17) for three of the application methods tested, indicating that estimations of dye half-lives could be used to predict those for endothal.     

Effects of feeding rate on growth performance and nutrient partitioning of young‐of‐the‐year white sturgeon (Acipenser transmontanus)

A 10‐week growth trial was performed to evaluate the effects of feeding rate on growth performance, nutrient partitioning, and to determine the optimum feeding rate for young‐of‐the‐year white sturgeon. Three tanks with 30 fish per tank each were assigned to five feeding rates, 0.4–2.0% body weight per day (BW day^?1). Weight gain significantly (P < 0.05) increased with increasing feeding rate up to 1.2% BW day^?1. Feed efficiency exhibited an inverse relationship to weight gain. Hepatosomatic and gonadal‐fat‐body (GFB)‐somatic indices were significantly affected by feeding rate, and the lowest values were observed at 0.4% BW day^?1. The increased feeding rate significantly affected whole‐body and carcass lipid and moisture contents. Protein gain in the carcass, but not in the GFB, was significantly influenced by feeding rate. Lipid gain in the carcass and GFB was also significantly affected by feeding rate. Four regression models were tested for the estimation of optimum feeding rate, including one‐slope straight broken‐line, two‐slope straight broken‐line, quadratic broken‐line and quadratic models. Adjusted coefficient of correlation and corrected Akaike information criterion were used to compare model performance. The quadratic broken‐line model was chosen as the best based on the criteria. The estimated optimum feeding rate for young‐of‐the‐year white sturgeon (360 g) is 1.5% BW day^?1.     

Primary anconeal fracture in a boxer

A 14-month-old speyed female Boxer was presented with acute non-weight-bearing lameness in the right forelimb. Radiography revealed separation of the anconeal process, which was thence surgically removed. Histological examination of the anconeal process confirmed a primary fracture. Isolated unilateral anconeal process fracture in the dog is rare and this report includes histopathological findings of a primary anconeal fracture.     

Biomass and nutrient accumulation in young Prosopis juliflora at Mombasa,Kenya

The biomass of a six-year-old plantation of Prosopis juliflora was determined using simple linear regressions of (y) the tree components: stem (over bark), large branches, small branches and leaves on (x), diameter at the base of the trees. Similar regressions were used to estimate height and volume produced by both stem and large branches. Macronutrient concentrations in the different tree components were determined and multiplied by the appropriate total dry weights to obtain total contents per hectare. The total stem volume (at age 6) was 209 m³/ha and large branch volume was 75 m³/ha. Total biomass was 216 tons/ha. Over 77% of the total biomass was accounted for by stem and large branches. Nevertheless, the leaves plus small branches (making 22.6% of the biomass) contained over 50% of the total pool of the individual nutrients N, P, K and Mg. The implications of this finding on site depletion due to total tree use as fuelwood and folder is discussed.     

Effect of dry period length on the effect of an intramammary teat sealant on the risk of mastitis in cattle treated with antibiotics at drying off

AIM: The aim of this study was to evaluate, under farm conditions, the use of a teat sealant in addition to whole herd dry cow antibiotic therapy on the risk of clinical mastitis in dairy cattle at pasture, and to evaluate the impact of dry period length on that risk and the impact of the teat sealant on that risk.

METHODS: Dairy cows in three herds which used routine whole herd antibiotic therapy were randomly assigned to receive either treatment with an internal teat sealant (n=322) or no additional treatment (n=313) at drying-off between March and May 2010. All clinical mastitis cases during the dry period and to the end of the subsequent lactation were recorded by farm staff; factors affecting risk of clinical mastitis were then analysed using a Cox proportional hazards model.

RESULTS: Median duration of the dry period was 112 days with >25% of cows having a dry period >130 days. The incidence risk of mastitis during lactation for cows treated with teat sealant was 9.9 (95% CI=6.9–13.7) cases per 100 cows compared with 17.9 (95% CI=13.8–22.6) cases per 100 cows for cows treated with antibiotic alone. The addition of a teat sealant to dry cow antibiotic therapy decreased the risk of clinical mastitis only in the first 33 days after calving (Hazard risk 0.24 (95% CI=0.12–0.48)). Length of dry period did not significantly affect the risk of clinical mastitis, or the effect of adding teat sealant to dry cow antibiotic therapy on the risk of clinical mastitis.

CONCLUSIONS: In these herds where, based on the mastitis history, whole herd antibiotic therapy had been recommended, the use of a teat sealant significantly reduced the risk of clinical mastitis. This effect was limited to the first 33 days after calving; subsequently there was no significant effect of treatment. There was no effect of dry period length on risk of clinical mastitis, nor any significant interaction with treatment.

CLINICAL RELEVANCE: Combination therapy with teat sealant and antibiotic was effective under New Zealand conditions in herds using whole herd antibiotic treatment at drying off. Teat sealant reduced risk of clinical mastitis in cattle with dry periods substantially longer than 100 days, and there was no evidence that this effect changed as dry period length increased.