609 research outputs found

    Relation of Sediment and Nutrient Loads to Watershed Characteristics and Land Use in the Otisco Lake Basin, Onondaga County, New York

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    Otisco Lake, the smallest and easternmost of New York State \u27s Finger Lakes, is the source of water supply for several villages in Onondaga County. In recent years, turbidity and algal blooms have periodically impaired the lake \u27s use for both water supply and recreation. Principal land uses within the Otisco Lake basin are woodland (39%) and cropland (49%). Conservation practices such as contour farming, strip cropping, and diversion ditches are applied to about 47% of the cropland in the basin. Runoff and concentrations of sediment and nutrients in the five major tributaries, which together drain about 70% of the lake \u27s watershed, were monitored from November 1981 through September 1983, and sediment and nutrient loads from the ungaged areas of the watershed were estimated. Otisco Lake received 10,600 tons of sediment, 20,600 lbs of phosphorus asp, 199,000 lbs of total kjeldahl nitrogen as N, and 236,000 lbs of nitrite plus nitrate as N from the five tributaries and the ungaged area during the 23-month study. Spafford Creek basin (12.0 sq mi) contributed about 72% of the annual sediment load and 46% of the annual nutrient load; the other four subbasins, which range from 2.6 to 3.7 sq mi in area, each contributed 3 to 5% of the annual sediment load and 6 to 16% of the annual nutrient load. The ungaged part of the watershed contributed 12% of the annual sediment load and 28% of the annual nutrient load. Concentrations of ammonia as N were relatively uniform through the year, although some extremely high concentrations occurred during the summer. Total Kjeldahl nitrogen concentrations were highest in the summer and lowest in the fall. Concentrations of nitrite plus nitrate were significantly lower in winter than in the rest of the year. Total phosphorus concentrations were slightly higher in the spring than at other times, and concentrations of dissolved phosphorus were slightly higher in the summer. Storms and snowmelt accounted for 70 to 90% of the runoff, 90 to 99% of the sediment load, and 70 to 98% of the nutrient loads from the tributaries. The largest nutrient loads occurred during the spring of each year, when runoff was highest. About 70% of the sediment, 60% of total Kjeldahl nitrogen, 58% of total phosphorus, and 53% of nitrite plus nitrate were transported during spring high flows. (Lantz-PTT

    Hemodynamics and Vascular Hypertrophy in African Americans and Caucasians With High Blood Pressure

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    BACKGROUND: Hypertension in African Americans is characterized by greater systemic vascular resistance (SVR) compared with Caucasian Americans, but the responsible mechanisms are not known. The present study sought to determine if peripheral vascular hypertrophy is a potential mechanism contributing to elevated SVR in African Americans with high blood pressure (BP). METHODS: In a biracial sample of 80 men and women between the ages of 25 and 45 years, with clinic BP in the range 130/85-160/99mm Hg, we assessed cardiac output and SVR, in addition to BP. Minimum forearm vascular resistance (MFVR), a marker of vascular hypertrophy, also was assessed. RESULTS: SVR was elevated in African Americans compared with Caucasians (P < 0.001). Regression models indicated that age, body mass index, 24-hour diastolic BP, and ethnicity were significant predictors of SVR. There was also a significant interaction between ethnicity and MFVR in explaining SVR in the study sample. In particular, there was a significant positive association between MFVR and SVR among African Americans (P = 0.002), whereas the association was inverse and not statistically significant among Caucasians (P = 0.601). CONCLUSION: Hypertrophy of the systemic microvasculature may contribute to the elevated SVR that is characteristic of the early stages of hypertension in African American compared with Caucasians

    Effects of Exercise and Sertraline on Measures of Coronary Heart Disease Risk in Patients With Major Depression: Results From the SMILE-II Randomized Clinical Trial

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    To assess the effects of supervised and home-based aerobic exercise training, and antidepressant pharmacotherapy (sertraline) on coronary heart disease (CHD) risk factors in a sample of participants with major depressive disorder (MDD)

    Exercise Fails to Improve Neurocognition in Depressed Middle-Aged and Older Adults

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    Purpose: Although cross-sectional studies have demonstrated an association between higher levels of aerobic fitness and improved neurocognitive function, there have been relatively few interventional studies investigating this relationship, and results have been inconsistent. We assessed the effects of aerobic exercise on neurocognitive function in a randomized controlled trial of patients with major depressive disorder (MDD). Methods: Two-hundred and two sedentary men (n = 49) and women (n = 153), aged 40 yr and over and who met diagnostic criteria for MDD, were randomly assigned to the following: a) supervised exercise, b) home-based exercise, c) sertraline, or d) placebo pill. Before and after 4 months of treatment, participants completed measures of: Executive Function (Trail Making Test BA difference score, Stroop Color/Word, Ruff 2 & 7 Test, Digit Symbol), Verbal Memory (Logical Memory, Verbal Paired Associates), and Verbal Fluency/Working Memory (Animal Naming, Controlled Oral Word Association Test, Digit Span). Multivariate analyses of covariance were performed to test the effects of treatment on posttreatment neuropsychological test scores, with baseline neuropsychological test scores, age, education, and change in depression scores entered as covariates. Results: The performance of exercise participants was no better than participants receiving placebo across all neuropsychological tests. Exercise participants performed better than participants receiving sertraline on tests of executive function but not on tests of verbal memory or verbal fluency/ working memory. Conclusions: We found little evidence to support the benefits of an aerobic exercise intervention on neurocognitive performance in patients with MDD. Originally published Medicine and Science in Sport and Exercise, Vol. 40, No. 7, July 200

    Ethnic Differences in the Effects of the DASH Diet on Nocturnal Blood Pressure Dipping in Individuals with High Blood Pressure

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    Ethnic differences in nocturnal blood pressure (BP) dipping may contribute to the increased risk for adverse cardiovascular events noted in African Americans (AAs). The DASH (Dietary Approaches to Stop Hypertension) diet has been shown to be efficacious in lowering clinic and ambulatory BP; however, the effect of the DASH diet on BP dipping is unclear
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