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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 184 (1989), S. 201-208 
    ISSN: 1573-5117
    Keywords: acidification ; algae ; Chrysochromulina ; Mougeotia ; photoinhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Blooms ofChrysochromulina breviturrita Nich. (Prymnesiophyceae) have been found to be restricted to lakes above pH 5.5 even though the alga is able to tolerate pH 4.0 in laboratory culture. A possible explanation is the increased transparency in acidifying lakes and a sensitivity ofC. breviturrita to high light intensities. A comparison was made withMougeotia sp., a filamentous green alga which co-occurs in moderately acidic lakes and has a similar pH tolerance range. This alga forms dense, floating mats or amorphous clouds in the upper littoral zone, where it would be exposed to full sunlight irradiances. In cultures ofC. breviturrita, prolonged exposures to 1600 µE · m−2 · s−1 (I0′) resulted in reductions in cell yield which were dependent age at the onset of exposure to high light intensity. Only cultures exposed to high light intensities during late stationary phase were able to recover to control levels and no recovery occurred if these cultures were nitrogen deficient.Mougeotia was more tolerant of both high light intensity and nitrogen limitation during the recovery period. The inability ofC. breviturrita to recover from the effects of high light intensity during nitrogen deprivation may be particularly important in small, stratified lakes which are undergoing acidification. The slow rate of vertical circulation, and increasing transparency, would prolong exposure of the alga to the high irradiance levels of nutrient-deficient epilimnetic waters. This suggests that the geographic distribution ofC. breviturrita may be explained in part by the increasing light intensities in lakes undergoing acidification.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 184 (1989), S. 201-208 
    ISSN: 1573-5117
    Keywords: acidification ; algae ; Chrysochromulina ; Mougeotia ; photoinhibition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Blooms ofChrysochromulina breviturrita Nich. (Prymnesiophyceae) have been found to be restricted to lakes above pH 5.5 even though the alga is able to tolerate pH 4.0 in laboratory culture. A possible explanation is the increased transparency in acidifying lakes and a sensitivity ofC. breviturrita to high light intensities. A comparison was made withMougeotia sp., a filamentous green alga which co-occurs in moderately acidic lakes and has a similar pH tolerance range. This alga forms dense, floating mats or amorphous clouds in the upper littoral zone, where it would be exposed to full sunlight irradiances. In cultures ofC. breviturrita, prolonged exposures to 1600 µE · m−2 · s−1 (I0′) resulted in reductions in cell yield which were dependent age at the onset of exposure to high light intensity. Only cultures exposed to high light intensities during late stationary phase were able to recover to control levels and no recovery occurred if these cultures were nitrogen deficient.Mougeotia was more tolerant of both high light intensity and nitrogen limitation during the recovery period. The inability ofC. breviturrita to recover from the effects of high light intensity during nitrogen deprivation may be particularly important in small, stratified lakes which are undergoing acidification. The slow rate of vertical circulation, and increasing transparency, would prolong exposure of the alga to the high irradiance levels of nutrient-deficient epilimnetic waters. This suggests that the geographic distribution ofC. breviturrita may be explained in part by the increasing light intensities in lakes undergoing acidification.
    Type of Medium: Electronic Resource
    Location Call Number Limitation Availability
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  • 3
    Publication Date: 2016-10-26
    Description: Background Psychosocial risk for cardiovascular disease (CVD) may be especially deleterious in persons with low socioeconomic status. Most work has focused on psychosocial factors individually, but emerging research suggests that the confluence of psychosocial risk may be particularly harmful. Using data from the Reasons for Geographical and Racial Differences in Stroke (REGARDS) study, we examined associations among depressive symptoms and stress, alone and in combination, and incident CVD and all-cause mortality as a function of socioeconomic status. Methods and Results At baseline, 22 658 participants without a history of CVD (58.8% female, 41.7% black, mean age 63.9±9.3 years) reported on depressive symptoms, stress, annual household income, and education. Participants were classified into 1 of 3 psychosocial risk groups at baseline: (1) neither depressive symptoms nor stress, (2) either depressive symptoms or stress, or (3) both depressive symptoms and stress. Cox proportional hazards models were used to predict physician-adjudicated incident total CVD events (nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death) and all-cause mortality over a median of 7.0 years (interquartile range 5.4–8.3 years) of follow-up. In fully adjusted models, participants with both depressive symptoms and stress had the greatest elevation in risk of developing total CVD (hazard ratio 1.48, 95% CI 1.21–1.81) and all-cause mortality (hazard ratio 1.33, 95% CI 1.13–1.56) but only for those with low income (〈$35 000) and not high (≥$35 000) income. This pattern of results was not observed in models stratified by education. Conclusions Findings suggest that screening for a combination of elevated depressive symptoms and stress in low-income persons may help identify those at increased risk of incident CVD and mortality.
    Keywords: Cardiovascular Disease, Epidemiology, Mental Health, Risk Factors
    Electronic ISSN: 2047-9980
    Topics: Medicine
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  • 4
    Publication Date: 2016-11-05
    Description: BackgroundPsychosocial risk for cardiovascular disease (CVD) may be especially deleterious in persons with low socioeconomic status. Most work has focused on psychosocial factors individually, but emerging research suggests that the confluence of psychosocial risk may be particularly harmful. Using data from the Reasons for Geographical and Racial Differences in Stroke (REGARDS) study, we examined associations among depressive symptoms and stress, alone and in combination, and incident CVD and all‐cause mortality as a function of socioeconomic status.Methods and ResultsAt baseline, 22 658 participants without a history of CVD (58.8% female, 41.7% black, mean age 63.9±9.3 years) reported on depressive symptoms, stress, annual household income, and education. Participants were classified into 1 of 3 psychosocial risk groups at baseline: (1) neither depressive symptoms nor stress, (2) either depressive symptoms or stress, or (3) both depressive symptoms and stress. Cox proportional hazards models were used to predict physician‐adjudicated incident total CVD events (nonfatal myocardial infarction, nonfatal stroke, and cardiovascular death) and all‐cause mortality over a median of 7.0 years (interquartile range 5.4–8.3 years) of follow‐up. In fully adjusted models, participants with both depressive symptoms and stress had the greatest elevation in risk of developing total CVD (hazard ratio 1.48, 95% CI 1.21–1.81) and all‐cause mortality (hazard ratio 1.33, 95% CI 1.13–1.56) but only for those with low income (
    Keywords: Cardiovascular Disease, Epidemiology, Mental Health, Risk Factors
    Electronic ISSN: 2047-9980
    Topics: Medicine
    Location Call Number Limitation Availability
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