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Consistent Impact (consistent + impact)

Distribution by Scientific Domains

Medical Sciences	37%
Life Sciences	37%

Selected Abstracts

Reassessing the impact of North Atlantic Oscillation on the sub-Saharan vegetation productivity

GLOBAL CHANGE BIOLOGY, Issue 4 2003
GUILING WANG
Abstract The Northern Atlantic Oscillation (NAO) has been shown to have a significant impact on the terrestrial ecosystem in the Sahelian region of Africa during the 1980s, and it has been strongly suggested that NAO may be a reliable predictor for the response of the Sahelian ecosystem to global climate variability. Using data from an extended period, we provide a reassessment for the impact of NAO on the Sahelian climate and ecosystem, and show that there is no consistent relationship between NAO and the ecosystem over Sahel. Statistical analysis on the NAO, vegetation, and precipitation data indicates that NAO influences the Sahelian vegetation productivity exclusively through its impact on precipitation. However, the relationship between the NAO index and Sahelian precipitation varies substantially with time. The correlation coefficient fluctuates between positive and negative values, and does not pass the 5% significance test during most of the twentieth century. The NAO system, although documented to govern the ecosystem dynamics over many other regions, does not have a consistent impact on the ecosystem over the Sahel. Therefore, the NAO index cannot produce a useful prediction on the ecosystem variability and changes in this region. This study provides an example that correlations based on short climate and ecological records (less than 20 years in this case) can be spurious and potentially misleading. [source]

The impact of land-cover modification on the June meteorology of China since 1700, simulated using a regional climate model

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2003
H. Wang
Abstract A series of simulations was conducted using a regional climate model with a domain covering mainland China. Simulations were conducted for a single June using estimated land cover for 1700, 1750, 1800, 1850, 1900, 1950, 1970 and 1990. The conversion of land cover between these periods was extensive over mainland China, where large areas were altered from natural forests to either grass or crops, or from natural grasslands to crops. These land-cover modifications affect various characteristics of the land surface, which lead to changes in the way available energy and water are partitioned. Over areas where land cover was modified, substantial changes are simulated. The conversion from forests to grasses or crops leads to warming and to reductions in root zone soil moisture and latent heat fluxes. Regionally, the conversion from forest to grasses and crops leads to significant warming over large areas of China, but there is an area of cooling present that is coincident with the main location of a land-use change from short grass to crops. The changes in temperature propagate to about 1500 m above the surface and affect specific humidity throughout this part of the atmosphere. An analysis of daily average results shows a consistent impact of land-cover modification on temperature, latent heat flux and soil moisture. Therefore, we find large and consistent impacts over China resulting from historical land-cover modification that are sufficiently important to the regional-scale climate to warrant inclusion in future modelling efforts. Our results suggest that efforts to attribute warming patterns over China to any particular cause need to take into account the conversion of the land cover that has taken place over China over the last 300 years. Copyright © 2003 Royal Meteorological Society [source]

Effect of generalist insect herbivores on introduced Lepidium draba (Brassicaceae): implications for the enemy release hypothesis

JOURNAL OF APPLIED ENTOMOLOGY, Issue 7 2008
K. P. Puliafico
Abstract The enemy release hypothesis (ERH) states that decreased regulation by natural enemies allows plants to increase in distribution, abundance and vigour following their introduction into an exotic range. Invasive plants rarely escape herbivory entirely, and for hoary cress [Lepidium draba L. (Brassicaceae)] it has been demonstrated that generalist insect abundance is greater in its introduced North American range than in the native European range. We assessed the role of increased generalist herbivory on hoary cress using representatives of four important herbivore niches commonly found in the introduced range. We experimentally examined the density dependent impact of these herbivores individually and in combination on hoary cress in a series of greenhouse experiments. We found that defoliation of the oligophagous diamondback moth Plutella xylostella (L.) (Lep., Plutellidae) had the strongest and most consistent impact, while damage by the stem-mining weevil Ceutorhynchus americanus Buchanan (Col., Curculionidae) tended to have the highest per capita effect. Plant response to feeding by the oligophagous crucifer flea beetle Phyllotreta cruciferae (Goeze) (Col., Chrysomelidae) was minor despite obvious feeding damage, and the impact of the polyphagous tarnished plant bug Lygus hesperus Knight (Het., Miridae) was negligible. In multiple-species experiments, herbivore impacts were usually additive. In general, we found that hoary cress can tolerate high densities of oligophagous insect herbivory and effectively resisted attack by the polyphagous L. hesperus, but also the oligophagous C. americanus. Our results indicate that a combination of plant resistance and tolerance allows hoary cress to withstand increased generalist herbivore load in its introduced range, consistent with the predictions of the ERH. [source]

Quantitative imaging of cartilage morphology at 3.0 Tesla in the presence of gadopentate dimeglumine (Gd-DTPA)

MAGNETIC RESONANCE IN MEDICINE, Issue 2 2007
Felix Eckstein
Abstract MRI-based cartilage morphometry was previously validated in the absence of gadopentate dimeglumine (Gd-DTPA). However, Gd-DTPA is required for compositional (proteoglycan) imaging using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). Therefore, the effect of Gd-DTPA on cartilage morphometry was studied. A total of 165 female participants (67 with and 98 without osteoarthritis [OA]) were imaged at 3.0 Tesla before and 2 hr after intravenous Gd-DTPA injection. Flip angles in post-Gd-DTPA scans varied between 12° and 35°. Cartilage volume and thickness of post- vs. pre-Gd-DTPA scans showed intraclass correlation coefficients (ICCs) of 0.85 , r , 0.95, mean differences between ,2.1% and +1.1%, and standard deviations (SDs) of differences between 4.7% and 9.2%. Mixed-effect models found no consistent impact of flip angle and OA status on post- vs. pre-Gd-DTPA differences. Accurate morphological measurements of cartilage can be obtained after Gd-DTPA injection, allowing compositional and morphological imaging to be combined into one session. Magn Reson Med 58:402,406, 2007. © 2007 Wiley-Liss, Inc. [source]

Nutrition and Physical Activity Interventions to Reduce Cardiovascular Disease Risk in Health Care Settings: A Quantitative Review with a Focus on Women

NUTRITION REVIEWS, Issue 7 2001
Sara Wilcox Ph.D.
The authors conducted a quantitative literature review of the impact of 32 diet and physical activity (PA) interventions delivered in health care settings on cardiovascular disease risk factors. Intervention effects were relatively modest but statistically significant for PA, body mass index or weight, dietary fat, blood pressure, and total and low-density lipoprotein serum cholesterol. Intervention effects were generally larger for samples with a mean age >50 years and for studies with <6 months follow-up. Type of comparison group, type of intervention, and use of a behavior theory did not have a consistent impact on intervention effects. Few studies focused on persons of color, although the results from these studies are promising. [source]

Factors of positive appraisal of care among Japanese family caregivers of older adults,

RESEARCH IN NURSING & HEALTH, Issue 5 2003
Noriko Yamamoto-Mitani
Abstract The purpose of this study was to examine factors of positive appraisal of care among Japanese family caregivers of older adults. The Positive Appraisal of Care (PAC) scale used in this study is a multidimensional Japanese measure and has four domains: relationship satisfaction, consequential gain, role confidence, and normative fulfillment. Three hundred and thirty-seven caregivers participated in this survey. Multiple regression analyses revealed that social support and caregiver belief in caregiving had a consistent impact on all domains of the PAC, whereas the impact of caregiver and care recipient characteristics varied among the domains. For example, caregiver age had a significant impact on role confidence and normative fulfillment but not on relationship satisfaction and consequential gain. The differential impact of caregiver and care recipient characteristics on the domains of the PAC underlines the usefulness of a multidimensional measurement. © 2003 Wiley Periodicals, Inc. Res Nurs Health 26:337,350, 2003 [source]

The impact of land-cover modification on the June meteorology of China since 1700, simulated using a regional climate model

Behavioural responses of dairy cattle to the stable fly, Stomoxys calcitrans, in an open field environment

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2006
B. A. Mullens
Abstract., Individual cows (25 in each of four herds) were monitored 8,10 times weekly for 12 weeks (stable fly season) on a southern California dairy, with 100 observations per cow. The numbers of biting stable flies, Stomoxys calcitrans (L.) (Diptera: Muscidae) on the front legs and the frequencies of four fly-repelling behaviours per 2-min observation period [head throws, front leg stamps, skin twitches (panniculus reflex) and tail flicks] were recorded. Fly numbers varied, peaking at 3.0,3.5 flies per leg in week 9 (late May). Weekly herd mean frequencies of fly-repelling behaviours were highly dependent on fly numbers, with a linear regression r2 > 0.8. Head throws and stamps were less frequent than skin twitches and tail flicks. Individual cows differed in numbers of stable flies and behaviours. Behaviours were correlated with flies for individual cows, but at a lower level than were herd means (r = 0.3,0.7). Cows that stamped more within a herd tended to have lower fly counts; other fly-repelling behaviours were less effective. Cows maintained ranks within a herd with regard to fly numbers (r = 0.47), head throws (0.48), leg stamps (0.64), skin twitches (0.69) and tail flicks (0.64). Older cows tended to harbour higher fly numbers and to stamp less relative to younger adult cows. Ratios of leg stamps and head throws to fly numbers dropped significantly through time, suggesting habituation to pain associated with fly biting. Tail flicks were not effective for repelling Stomoxys, but were easiest to quantify and may help in monitoring pest intensity. At this low,moderate fly pressure, no consistent impacts on milk yield were detected, but methods incorporating cow behaviour are recommended for future studies of economic impact. [source]