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Variance Attributable (variance + attributable)

Distribution by Scientific Domains
Medical Sciences40%
Life Sciences40%

Selected Abstracts

Depression and obesity: do shared genes explain the relationship?

DEPRESSION AND ANXIETY, Issue 9 2010
Niloofar Afari Ph.D.
Abstract Background: Studies have found a modest association between depression and obesity, especially in women. Given the substantial genetic contribution to both depression and obesity, we sought to determine whether shared genetic influences are responsible for the association between these two conditions. Methods: Data were obtained from 712 monozygotic and 281 dizygotic female twin pairs who are members of the community-based University of Washington Twin Registry. The presence of depression was determined by self-report of doctor-diagnosed depression. Obesity was defined as body mass index of ,30,kg/m2, based on self-reported height and weight. Generalized estimating regression models were used to assess the age-adjusted association between depression and obesity. Univariate and bivariate structural equation models estimated the components of variance attributable to genetic and environmental influences. Results: We found a modest phenotypic association between depression and obesity (odds ratio=1.6, 95% confidence interval=1.2,2.1). Additive genetic effects contributed substantially to depression (57%) and obesity (81%). The best-fitting bivariate model indicated that 12% of the genetic component of depression is shared with obesity. Conclusions: The association between depression and obesity in women may be in part due to shared genetic risk for both conditions. Future studies should examine the genetic, environmental, social, and cultural mechanisms underlying the relationship between this association. Depression and Anxiety, 2010. © 2010 Wiley-Liss, Inc. [source]

Increased mite parasitism as a cost of testosterone in male striped plateau lizards Sceloporus virgatus

FUNCTIONAL ECOLOGY, Issue 2 2007
ROBERT M. COX
Summary 1Testosterone (T) co-ordinates the seasonal and sex-specific expression of numerous physiological, behavioural and morphological traits that contribute to male reproductive success. However, increased susceptibility to parasitism has been proposed as a potential cost of elevated plasma T. 2During the spring breeding season, male striped plateau lizards Sceloporus virgatus harbour significantly more ectoparasitic mite larvae (Acari: Trombiculidae) than females. Plasma T levels are also elevated in males at this time, suggesting that sex differences in mite parasitism may be driven by underlying sex differences in circulating T. 3We tested this hypothesis experimentally by manipulating plasma T levels of yearling males via surgical castration and exogenous T implants. Upon recapture of free-living animals, we found significantly fewer mites on castrated males relative to either intact controls or castrated males that received T implants. 4After removing variance attributable to treatment effects, we observed (1) a positive correlation between residual measures of plasma T and mite load, and (2) a negative correlation between residual measures of mite load and growth rate. These correlations suggest a growth cost associated with mite parasitism. 5Previous studies have shown that exogenous T increases parasitism, but ours is one of the few to show that castration also reduces parasitism. This result, coupled with the fact that our induced plasma T levels remain within physiological limits, makes this one of the clearest demonstrations of a functional relationship between T and parasitism in any free-living vertebrate. [source]

Sub-saharan desertification and productivity are linked to hemispheric climate variability

GLOBAL CHANGE BIOLOGY, Issue 3 2001
Gufu Oba
Summary Vegetation productivity and desertification in sub-Saharan Africa may be influenced by global climate variability attributable to the North Atlantic Oscillation (NAO) and El Niño Southern Oscillation (ENSO). Combined and individual effects of the NAO and ENSO indices revealed that 75% of the interannual variation in the area of Sahara Desert was accounted for by the combined effects, with most variance attributable to the NAO. Effects were shown in the latitudinal variation on the 200 mm isocline, which was influenced mostly by the NAO. The combined indices explained much of the interannual variability in vegetation productivity in the Sahelian zone and southern Africa, implying that both the NAO and ENSO may be useful for monitoring effects of global climate change in sub-Saharan Africa. [source]

Measuring Word of Mouth's Impact on Theatrical Movie Admissions

JOURNAL OF ECONOMICS & MANAGEMENT STRATEGY, Issue 4 2007
Charles C. Moul
Information transmission among consumers (i.e., word of mouth) has received little empirical examination. I offer a technique that can identify and measure the impact of word of mouth, and apply it to data from U.S. theatrical movie admissions. While variables and movie fixed effects comprise the bulk of observed variation, the variance attributable to word of mouth is statistically significant. Results indicate approximately 10% of the variation in consumer expectations of movies can be directly or indirectly attributed to information transmission. Information appears to affect consumer behavior quickly, with the length of a movie's run mattering more than the number of prior admissions. [source]

Homophobia and Conservative Religion: Toward a More Nuanced Understanding

AMERICAN JOURNAL OF ORTHOPSYCHIATRY, Issue 1 2007
Christopher H. Rosik PhD
The failure of homophobia scales to consider the normative assumptions of religious communities may result in findings that are less useful in addressing this problem. In this study, 155 undergraduate students at a Christian university were surveyed, separately assessing attitudes toward celibate versus sexually active homosexual men and women. Results of multiple regression analyses found that participants who emphasized a person-behavior distinction (an accepted tenet of conservative religious ideology) held more negative attitudes toward lesbian women than those who were comparatively more accepting and did not emphasize such a distinction. However, participants who emphasized the person-behavior distinction held more positive attitudes toward gay men than those who were comparatively more rejecting and did not emphasize such a distinction. These relationships were significant even after accounting for variance attributable to general measures of religious commitment. Attempts to reduce homophobia within conservative religious communities may benefit from a more sensitive approach to their belief systems. [source]