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Greater Vulnerability (greater + vulnerability)
Selected AbstractsEcological implications of xylem cavitation for several Pinaceae in the Pacific Northern USAFUNCTIONAL ECOLOGY, Issue 5 2000J. Piñol Abstract 1.,Xylem hydraulic properties and vulnerability to cavitation (determined using the air-injection method) were studied in six Pinaceae of the northern Rocky Mountains: Pinus ponderosa, Pseudotsuga menziesii, Larix occidentalis, Pinus contorta, Pinus albicaulis and Abies lasiocarpa. We tested whether species extending into drier habitats exhibited increased resistance to water stress-induced cavitation, and whether there is a trade-off between xylem transport capacity and resistance to cavitation. 2.,At lower elevations the more drought-tolerant P. ponderosa was much less resistant to cavitation than the codominant P. menziesii. Greater vulnerability to cavitation in P. ponderosa was compensated for, at least in part, by increased stomatal control of water loss (inferred from carbon isotope discrimination) and by increased sapwood to leaf area ratios. Similar differences, but less pronounced, were found in codominant species at higher elevations. 3.,Leaf specific hydraulic conductivity was negatively correlated with mean cavitation pressure. When species were separated into pines and non-pines, sapwood specific conductivity and mean cavitation pressure were also negatively correlated within each of the two groups. 4.,Our results indicate that within the evergreen conifers examined, greater resistance to water stress-induced cavitation is not required for survival in more xeric habitats, and that there is a trade-off between xylem conductance and resistance to cavitation. [source] Ontogenetic switches from plant resistance to tolerance: minimizing costs with age?ECOLOGY LETTERS, Issue 3 2007Karina Boege Abstract Changes in herbivory and resource availability during a plant's development should promote ontogenetic shifts in resistance and tolerance, if the costs and benefits of these basic strategies also change as plants develop. We proposed and tested a general model to detect the expression of ontogenetic tradeoffs for these two alternative anti-herbivory strategies in Raphanus sativus. We found that ontogenetic trajectories occur in both resistance and tolerance but in opposite directions. The juvenile stage was more resistant but less tolerant than the reproductive stage. The ontogenetic switch from resistance to tolerance was consistent with the greater vulnerability of young plants to leaf damage and with the costs of resistance and tolerance found at each stage. We posit that the ontogenetic perspective presented here will be helpful in resolving the current debate on the existence and detection of a general resistance,tolerance tradeoff. [source] Chronic alcohol consumption increases the sensitivity of rat liver mitochondrial respiration to inhibition by nitric oxideHEPATOLOGY, Issue 1 2003Aparna Venkatraman Chronic alcohol consumption is a well-known risk factor for hepatic injury, and mitochondrial damage plays a significant role in this process. Nitric oxide (NO) is an important modulator of mitochondrial function and is known to inhibit mitochondrial respiration. However, the impact of chronic alcohol consumption on NO-dependent control of liver mitochondrial function is unknown. This study examines the effect of alcohol exposure on liver mitochondria in a rat model and explores the interaction of NO and mitochondrial respiration in this context. Mitochondria were isolated from the liver of both control and ethanol-fed rats after 5 to 6 weeks of alcohol consumption. Mitochondria isolated from ethanol-treated rats showed a significant decrease in state 3 respiration and respiratory control ratio that was accompanied by an increased sensitivity to NO-dependent inhibition of respiration. In conclusion, we show that chronic alcohol consumption leads to increased sensitivity to the inhibition of respiration by NO. We propose that this results in a greater vulnerability to hypoxia and the development of alcohol-induced hepatotoxicity. [source] Transcallosal White Matter Degradation Detected With Quantitative Fiber Tracking in Alcoholic Men and Women: Selective Relations to Dissociable FunctionsALCOHOLISM, Issue 7 2010Adolf Pfefferbaum Introduction:, Excessive alcohol consumption can adversely affect white matter fibers and disrupt transmission of neuronal signals. Here, we examined six anatomically defined transcallosal white matter fiber bundles and asked whether any bundle was specifically vulnerable to alcohol, what aspect of white matter integrity was most affected, whether women were more vulnerable than men, and whether evidence of compromise in specific bundles was associated with deficits in balance, sustained attention, associative learning, and psychomotor function, commonly affected in alcoholics. Methods:, Diffusion tensor imaging quantitative fiber tracking assessed integrity of six transcallosal white matter bundles in 87 alcoholics (59 men, 28 women) and 88 healthy controls (42 men, 46 women). Measures included orientational diffusion coherence (fractional anisotropy, FA) and magnitude of diffusion, quantified separately for axial (longitudinal; ,L) and radial (transverse; ,T) diffusivity. The Digit Symbol Test and a test of ataxia were also administered. Results:, Alcoholism negatively affected callosal FA and ,T of all but the sensory-motor bundle. Women showed no evidence for greater vulnerability to alcohol than men. Multiple regression analyses confirmed a double dissociation: higher diffusivity in sensory-motor and parietal bundles was associated with poorer balance but not psychomotor speed, whereas higher diffusivity in prefrontal and temporal bundles was associated with slower psychomotor speed but not balance. Conclusions:, This study revealed stronger alcohol effects for FA and radial diffusivity than axial diffusivity, suggesting myelin degradation, but no evidence for greater vulnerability to alcohol in women than men. The presence of brain-behavior relationships provides support for the role of alcoholism-related commissural white matter degradation as a substrate of cognitive and motor impairment. Identification of a double dissociation provides further support for the role of selective white matter integrity in specific domains of performance. [source] Psychosocial functioning and career decision-making in Israeli adolescent and young adult cancer survivors,,PEDIATRIC BLOOD & CANCER, Issue 4 2010Marilyn Stern PhD Abstract Objectives This study examined how dispositional optimism, health vulnerability, and time perspective were related to adolescent and young adult (AYA) cancer survivors' career decision-making (CDM) and quality of life (QOL). Secondarily, how cultural factors relate to CDM and QOL among Israeli-Jewish and Israeli-Arab cancer survivors was explored. Methods Fifty-one cancer survivors (68.6% females, 80.4% Israeli-Jewish, 19.6% Israeli-Arab, Mage,=,21.45 years), at least 6 months post-active treatment (Mtime,=,5.75 years) completed self-report questionnaires. Results Multiple regression analyses indicated that optimism, vulnerability, and past negative, present fatalistic, and future time perspective were significantly associated with QOL (F(6, 47),=,6.80, P,<,0.001) and CDM (F(6, 47),=,2.46, P,<,0.04). Perceived vulnerability explained the main portion of QOL variance with greater vulnerability associated with lowered QOL (,,=,0.33, P,<,0.001). Optimism was positively associated with QOL (,,=,0.55, P,<,0.02). Greater present fatalistic time perspective was associated with greater CDM difficulties (,,=,0.32, P,<,0.05). Multivariate analyses indicated greater past negative time perceptions (F(1, 46),=,8.92, P,<,0.005) and fatalism about the future (F(1, 46),=,5.90, P,<,0.02) among Israeli-Arabs as compared to Israeli-Jewish survivors. Israeli-Jewish survivors were more optimistic than Israeli-Arab survivors (F(1, 46),=,3.48, P,<,0.065). Conclusions Vulnerability, optimism, and time perspective were significantly associated with QOL and CDM among Israeli AYA cancer survivors. Israeli-Arabs viewed their pasts and futures more negatively and reported lower optimism than Israeli-Jews. Implications for future research and interventions were considered. Pediatr Blood Cancer. 2010;55:708,713. © 2010 Wiley-Liss, Inc. [source] Hydraulic properties and freezing-induced cavitation in sympatric evergreen and deciduous oaks with contrasting habitatsPLANT CELL & ENVIRONMENT, Issue 12 2001J. Cavender-Bares Abstract We investigated the hydraulic properties in relation to soil moisture, leaf habit, and phylogenetic lineage of 17 species of oaks (Quercus) that occur sympatrically in northern central Florida (USA). Leaf area per shoot increased and Huber values (ratio of sapwood area to leaf area) decreased with increasing soil moisture of species' habitats. As a result, maximum hydraulic conductance and maximum transpiration were positively correlated with mean soil moisture when calculated on a sapwood area basis, but not when calculated on a leaf area basis. This reveals the important role that changes in allometry among closely related species can play in co-ordinating water transport capacity with soil water availability. There were significant differences in specific conductivity between species, but these differences were not explained by leaf habit or by evolutionary lineage. However, white oaks had significantly smaller average vessel diameters than red oaks or live oaks. Due to their lower Huber values, maximum leaf specific conductivity (KL) was higher in evergreen species than in deciduous species and higher in live oaks than in red oaks or white oaks. There were large differences between species and between evolutionary lineages in freeze,thaw-induced embolism. Deciduous species, on average, showed greater vulnerability to freezing than evergreen species. This result is strongly influenced by evolutionary lineage. Specifically, white oaks, which are all deciduous, had significantly higher vulnerability to freezing than live oaks (all evergreen) and red oaks, which include both evergreen and deciduous species. These results highlight the importance of taking evolutionary lineage into account in comparative physiological studies. [source] Gambling and older people in AustraliaAUSTRALASIAN JOURNAL ON AGEING, Issue 3 2003John McCormack Objectives: There is a dearth of studies on the gambling behaviour of older people in Australia. This study aims to address that gap in local knowledge by investigating the gambling activity of older people in the general community, as well as the situation of older gamblers who attend counselling services for people with problem gambling behaviour. Method: The study draws on a recent national gambling survey to review older peoples' gambling in the general community, and then uses data from Victorian Gamblers' Help counselling services to review the gambling problems and treatment needs of older problem gamblers. Results: Older people gamble at a slightly lower rate than younger groups in the general community. Older problem gamblers similarly appear to have less serious problems than younger groups although there is a small group with quite severe problems as a result of gambling. There are more older female problem gamblers in counselling than males, but older men present more serious problems. Treatment responses appear to be effective for this age group. Conclusion: As older age is currently characterised by a low fixed income and thus greater vulnerability to the adverse consequences of gambling, research should continue to monitor the gambling impact on older people as our population ages. [source] | |||||||||||||