The effect of spring burning on competitive ranking of prairie species

A common explanation for the changes in species abundance following a fire is a shift in competitive ranking. However, experimental tests have been inconsistent and generally do not support this explanation. I examined the competitive ability of an abundant C 4 grass, Andropogon gerardii , and a C 3 forb, Ratibida pinnata , in a prairie remnant in northern Ohio, USA, for each of three years following a spring burn in 1996. While the abiotic environment directly influenced both species similarly, relative competitive abilities in terms of growth changed markedly: in 1996 Andropogon was less inhibited by neighbors; in 1997 both Andropogon and Ratibida had similar competitive abilities; and in 1998 Ratibida was less inhibited by neighbors. This shift in competitive response ranking paralleled the changes in relative abundance for the two species. In contrast, the effect of neighbors on survival changed markedly over time but did not differ among the two species. Thus, fire may influence species abundance through changing species competitive response ranking, at least in terms of growth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72362/1/3236873.pd

Realism, Liberalism and Non-ideal Theory Or, Are there Two Ways to do Realistic Political Theory?

The charge that contemporary political theory has lost touch with the realities of politics is common to both the recent ideal/non-ideal theory debate and the revival of interest in realist thought. However, a tendency has arisen to subsume political realism within the ideal/non-ideal theory debate, or to elide realism with non-ideal theorising. This article argues that this is a mistake. The ideal/non-ideal theory discussion is a methodological debate that takes place within the framework of liberal theory. Realism, contrary to several interpretations, is a distinct and competing conception of politics in its own right that stands in contrast to that of liberal theory. While the two debates are united in a sense that contemporary liberal theory needs to be more realistic, they differ significantly in their understanding of this shortcoming and, more importantly, what it is to do more realistic political theory

Pessimism and the risk for coronary heart disease among middle-aged and older Finnish men and women: a ten-year follow-up study

This was a ten-year prospective cohort study on a regional sample of three cohorts aged 52–56, 62–66 and 72–76 years at baseline (N = 2815). The study groups were personally interviewed four times (in 2002, 2005, 2008 and 2012). The revised Life Orientation Test (LOT-R) was completed at the first appointment to determine the level of dispositional optimism or pessimism. During the ten-year follow-up, the incidence of new cases of coronary heart diseases was measured. The association between dispositional optimism/pessimism and the incidence of CHD during the follow-up was studied with logistic regression. Results Those who developed coronary heart disease during the ten-year follow-up were significantly more pessimistic at baseline than the other subjects. Using multivariate logistic regression models separately for men and women, we noticed no elevated risk for CHD in the pessimistic women compared to the non-pessimistic women. However, among men in the highest quartile of pessimism, the risk for CHD was approximately four-fold (OR 4.11, 95 % CI 1.68–11.04) that of the men in the lowest quartile. Optimism did not seem to have any role in the risk for developing CHD. Discussion Our main finding is that pessimism seemed to be a clear risk factor for coronary heart disease in men even after adjusting for classical well-known risk factors while optimism did not seem to be a protective factor. Connection between pessimism and coronary heart disease was not detectable among women. Similar gender differences between psychosocial factors and overall well-being have been noticed in some earlier studies, too. The mechanism of this gender difference is not fully understood. Differences between men and women in somatic responses to stress found in earlier studies may at least partly explain this phenomenon. The impact of optimism and pessimism on cardiovascular disease has been studied earlier and several possible mechanisms have been discovered but it seems clear that they cannot fully explain the association. For example, optimists have healthier lifestyles which lowers the risk for coronary heart disease, but pessimism was established to be a risk factor for cardiovascular disease in our study even in logistic regressions including the best known classical risk factors, e.g. smoking and high level of blood glucose. According to our study it is important to pay attention also to the psychosocial components in addition to the well-known risk factors when planning the prevention of coronary heart disease. Measuring pessimism is quite easy and it consumes very little time. Once the amount of pessimism is ascertained, it is easier to define who is in the greatest need of preventive actions concerning coronary heart disease. Conclusions Pessimism seems to be a substantial risk factor for CHD, and as an easily measured variable it might be a very useful tool together with the well-known physiological risk factors to determine the risk for developing CHD, at least among men.BioMed Central open acces

Multiple dimensions of health locus of control in a representative population sample: ordinal factor analysis and cross-validation of an existing three and a new four factor model

<p>Abstract</p> <p>Background</p> <p>Based on the general approach of locus of control, health locus of control (HLOC) concerns control-beliefs due to illness, sickness and health. HLOC research results provide an improved understanding of health related behaviour and patients' compliance in medical care. HLOC research distinguishes between beliefs due to Internality, Externality powerful Others (POs) and Externality Chance. However, evidences for differentiating the POs dimension were found. Previous factor analyses used selected and predominantly clinical samples, while non-clinical studies are rare. The present study is the first analysis of the HLOC structure based on a large representative general population sample providing important information for non-clinical research and public health care.</p> <p>Methods</p> <p>The standardised German questionnaire which assesses HLOC was used in a representative adult general population sample for a region in Northern Germany (N = 4,075). Data analyses used ordinal factor analyses in LISREL and Mplus. Alternative theory-driven models with one to four latent variables were compared using confirmatory factor analysis. Fit indices, chi-square difference tests, residuals and factor loadings were considered for model comparison. Exploratory factor analysis was used for further model development. Results were cross-validated splitting the total sample randomly and using the cross-validation index.</p> <p>Results</p> <p>A model with four latent variables (Internality, Formal Help, Informal Help and Chance) best represented the HLOC construct (three-dimensional model: normed chi-square = 9.55; RMSEA = 0.066; CFI = 0.931; SRMR = 0.075; four-dimensional model: normed chi-square = 8.65; RMSEA = 0.062; CFI = 0.940; SRMR = 0.071; chi-square difference test: p < 0.001). After excluding one item, the superiority of the four- over the three-dimensional HLOC construct became very obvious (three-dimensional model: normed chi-square = 7.74; RMSEA = 0.059; CFI = 0.950; SRMR = 0.079; four-dimensional model: normed chi-square = 5.75; RMSEA = 0.049; CFI = 0.965; SRMR = 0.065; chi-square difference test: p < 0.001). Results were confirmed by cross-validation. Results based on our large community sample indicated that western general populations separate health-related control-beliefs concerning formal and informal assistance.</p> <p>Conclusions</p> <p>Future non-clinical HLOC studies in western cultures should consider four dimensions of HLOC: Internality, Formal Help, Informal Help and Chance. However, the standardised German instrument needs modification. Therefore, confirmation of our results may be useful. Future research should compare HLOC structure between clinical and non-clinical samples as well as cross-culturally.</p