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Observed Relationships (observed + relationships)
Selected AbstractsAlcohol control policies and alcohol consumption by youth: a multi-national studyADDICTION, Issue 11 2009Mallie J. Paschall ABSTRACT Aims The study examined relationships between alcohol control policies and adolescent alcohol use in 26 countries. Design Cross-sectional analyses of alcohol policy ratings based on the Alcohol Policy Index (API), per capita consumption and national adolescent survey data. Setting Data are from 26 countries. Participants Adolescents (aged 15,17 years) who participated in the 2003 European School Survey Project on Alcohol and Other Drugs (ESPAD) or national secondary school surveys in Spain, Canada, Australia, New Zealand and the United States. Measurements Alcohol control policy ratings based on the API; prevalence of alcohol use, heavy drinking and first drink by age 13 based on national secondary school surveys; per capita alcohol consumption for each country in 2003. Analysis Correlational and linear regression analyses were conducted to examine relationships between alcohol control policy ratings and past 30-day prevalence of adolescent alcohol use, heavy drinking and having first drink by age 13. Per capita consumption of alcohol was included as a covariate in regression analyses. Findings More comprehensive API ratings and alcohol availability and advertising control ratings were related inversely to the past 30-day prevalence of alcohol use and prevalence rates for drinking three to five times and six or more times in the past 30 days. Alcohol advertising control was also related inversely to the prevalence of past 30-day heavy drinking and having first drink by age 13. Most of the relationships between API, alcohol availability and advertising control and drinking prevalence rates were attenuated and no longer statistically significant when controlling for per capita consumption in regression analyses, suggesting that alcohol use in the general population may confound or mediate observed relationships between alcohol control policies and youth alcohol consumption. Several of the inverse relationships remained statistically significant when controlling for per capita consumption. Conclusions More comprehensive and stringent alcohol control policies, particularly policies affecting alcohol availability and marketing, are associated with lower prevalence and frequency of adolescent alcohol consumption and age of first alcohol use. [source] Quantitative aspects of the regulation of ovarian development in selected anautogenous Diptera: integration of endocrinology and nutritionENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2001L. Barton Browne Abstract Aspects of the influence of nutrition on the degree of ovarian development in selected anautogenous Diptera are reviewed. The Diptera considered are several mosquito species, with emphasis on Aedes aegypti, the house fly, Musca domestica, the Australian bush fly, M. vetustissima and the blowflies, Lucilia cuprina and Phormia regina. All the selected species display discrete ovarian cycles in which all oocytes destined to reach maturity in a particular ovarian cycle develop synchronously. In these species, the proportion of females maturing oocytes and, where such data exist, the number of oocytes they mature are positively correlated with the amount of any particular nitrogen-containing material ingested or given by enema or by infusion. In addition, the degree of ovarian development may be affected by the chemical composition of nitrogen-containing food. Possible physiological bases for the observed relationships are discussed. Available evidence suggests that whether or not a female matures any oocytes is hormonally regulated and that the number of oocytes matured is probably regulated by the availability of nutrients. Some approaches that might further elucidate the physiological regulatory mechanisms involved in ovarian development are outlined. [source] Using propensity scores to estimate the effects of insecticides on stream invertebrates from observational data,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2009Lester L. Yuan Abstract Analyses of observational data can provide insights into relationships between environmental conditions and biological responses across a broader range of natural conditions than experimental studies, potentially complementing insights gained from experiments. However, observational data must be analyzed carefully to minimize the likelihood that confounding variables bias observed relationships. Propensity scores provide a robust approach for controlling for the effects of measured confounding variables when analyzing observational data. Here, we use propensity scores to estimate changes in mean invertebrate taxon richness in streams that have experienced insecticide concentrations that exceed aquatic life use benchmark concentrations. A simple comparison of richness in sites exposed to elevated insecticides with those that were not exposed suggests that exposed sites had on average 6.8 fewer taxa compared to unexposed sites. The presence of potential confounding variables makes it difficult to assert a causal relationship from this simple comparison. After controlling for confounding factors using propensity scores, the difference in richness between exposed and unexposed sites was reduced to 4.1 taxa, a difference that was still statistically significant. Because the propensity score analysis controlled for the effects of a wide variety of possible confounding variables, we infer that the change in richness observed in the propensity score analysis was likely caused by insecticide exposure. [source] Personality, gender, and cryingEUROPEAN JOURNAL OF PERSONALITY, Issue 1 2001Mathell Peter This study examined gender differences in crying as well as associations between basic personality traits and self-reported indices of crying. Forty-eight men and 56 women completed the Five-Factor Personality Inventory and the Adult Crying Inventory. Substantial gender differences were demonstrated in crying frequency and crying proneness, but not with respect to mood changes after crying. As predicted, women reported a higher frequency of crying and more proneness to cry both for negative and positive reasons. For women, all these crying indices were negatively associated with Emotional Stability. For men, only a significant negative relationship between Emotional Stability and crying for negative reasons emerged. No clear links were found between personality and mood changes after crying. Multiple regression analysis revealed a significant predictive role of gender for crying proneness, even when controlling for personality differences, but not for crying frequency. Adding personality by gender interaction terms resulted in a disappearance of the main effect of sex, while significant interactions with personality factors showed up for crying frequency and general crying proneness. It is suggested that future research on the relationship between personality and crying should focus more on the underlying mechanisms of observed relationships. Furthermore, it is recommended that future research should examine the role of different emotion regulation strategies. In addition, biological factors, temperament, upbringing measures, and socio-demographic variables should be taken into account. Copyright © 2001 John Wiley & Sons, Ltd. [source] Red Cell Pulmonary Transit Times Through the Healthy Human LungEXPERIMENTAL PHYSIOLOGY, Issue 2 2003G. S. Zavorsky It has previously been postulated that rapid red cell capillary transit through the human lung plays a role in the mechanism of diffusion limitation in some endurance athletes. Methodological limitations currently prevent researchers from directly measuring pulmonary capillary transit times in humans during exercise; however, first pass radionuclide cardiography allows direct measurement of red blood cell (RBC) transit times through the whole lung at various exercise intensities. We examined the relationship between mean whole lung red cell pulmonary transit times (cardiopulmonary transit times or CPTT) and different levels of flow in 88 healthy humans (76 males, 12 females) from several studies (mean age 31 years). The pooled data suggest that the relationship between CPTT and cardiac index (CI), beginning at rest and progressing through to maximum exercise demonstrates that CPTT reaches its minimum value when CI is about 8.1 l m2 min,1 (2.5-3 times the CI value at rest), and does not significantly change with further increases in CI. Cardiopulmonary blood volume (CPBV) index also does not change significantly until CI reaches 2.5 to 3 times the CI value at rest and then increases roughly linearly after that point. Consequently, the systematic increase in CPBV index with increasing pulmonary blood flow between 8.1 and 20 l m2 min,1 displays an adaptive response of the cardiopulmonary system by augmenting CPBV (and perhaps pulmonary capillary blood volume through distension and recruitment) to offset the reduction in CPTT, as no significant difference in mean CPTT is observed between these levels of flow (P > 0.05). Therefore, these data demonstrate that CPBV does not reach maximum capacity during strenuous or maximum exercise. This does not support the principle of quarter-power allometric scaling for flow when explaining modifications during exercise. Therefore, we speculate that the observed relationships between CPTT, CBPV index and flow may prevent mean CPTT (and perhaps mean pulmonary capillary transit times) from decreasing below the threshold time required for oxygenation. [source] Sperm length in sand martins Riparia riparia: a comment on Helfenstein et alJOURNAL OF AVIAN BIOLOGY, Issue 3 2009Oddmund Kleven How long is a sand martin Riparia riparia spermatozoon? In a recent study, Helfenstein et al. (2008) presented data on the intraspecific variation in sperm length, swimming speed and longevity in this species and some interesting correlations between these variables. However, the reported sperm lengths are remarkably short for the species, which casts doubts about whether sperm total length has actually been measured and how the observed relationships should be interpreted. [source] Space,time patterns of co-variation of biodiversity and primary production in phytoplankton guilds of coastal marine environmentsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2003Maria Rosaria Vadrucci Abstract 1.The relevance of biodiversity to ecosystem processes is a major topic in ecology. Here, we analyse the relationship between biodiversity and productivity of the nano- and micro-phytoplankton guilds in coastal marine ecosystems. 2.The patterns of variation of species richness, diversity and primary productivity (as 14C assimilation) were studied in two marine areas: a eutrophic,mesotrophic area beside the River Po delta (northern Adriatic) and an oligotrophic area around the Salento peninsula (southern Adriatic,Ionian). The study was carried out at 23 sites in the northern area and at 45 sites in the southern area. Sites were arranged on expected spatial and temporal gradients of primary productivity variation, according to distance from the coast, optical depths and seasonal period. 3.167 taxa were identified in the northern area and 153 taxa in the southern area. In both areas, the taxonomic composition of the nano- and micro-phytoplankton guilds exhibited greater temporal than spatial variation. The latter was much higher in the southern area than in the northern area (average dissimilarity between stations being 70.7±0.8% and 44.7±4.2% respectively). 4.Primary productivity varied in space and time on the gradients considered. Phytoplankton species richness and diversity exhibited significant patterns of variation in space and time; overall, these were inversely related to the primary productivity patterns in the northern area, whereas they were directly related in the southern area. 5.The small individual size and the high turnover rate of phytoplankton are likely to underlie the observed relationships, which emphasized a threshold response to nutrient enrichment in agreement with the ,paradox of enrichment'. Under resource enrichment conditions, the high turnover of producers leads to hierarchical partitioning of the available resources with an increasing dominance of a few species. Therefore, the relationship observed here seems likely to be explained by the complementarity hypothesis. Copyright © 2003 John Wiley & Sons, Ltd. [source] Avian eggshell coloration: new perspectives on adaptive explanationsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010MICHAEL I. CHERRY Recent work suggests that the evolution of egg coloration may have been constrained in three important ways that have not yet been critically synthesized in any review. First, on account of birds being able to see in the ultraviolet spectrum, the interaction between the properties of avian vision and the light environment of nests imply different perceptions of egg coloration from those experienced by humans. Second, a new hypothesis to explain blue,green egg coloration interprets it as a sexually selected signal to males of the laying female's genetic quality. Third, evidence from taxa as divergent as sparrowhawks and great tits indicates that protoporphyrin pigments responsible for maculation (spotting patterns) have a structural function in compensating for eggshell thinning, as caused by calcium stress, and, more recently, dichlorodiphenyltrichloroethane. We consider this to be the most convincing explanation for the primary function of spotting, although an important secondary function might arise through the fact that individual patterns of maculation may allow birds to identify their own eggs, effectively serving as signatures in the face of inter- or intra-specific brood parasitism. These constraints or hypotheses are not mutually exclusive, and should not be taken to imply that one, but not other, agents of selection might apply to any one species. However, the sexually-selected eggshell coloration hypothesis is least plausible for hole-nesting birds because of the poor light quality available, although such species have been the focus of research in this area, and only a single experimental study has shown a link between egg coloration and male provisioning. Furthermore, the observed relationships between female phenotypic quality and egg traits do not necessarily imply that they have signalling functions. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 753,762. [source] | ||||||||||