Correlation Of Shoulder And Elbow Kinetics With Ball Velocity In College Baseball Pitchers

Specific injuries at the elbow and glenohumeral joints have been linked to several kinetic variables that occur throughout the throwing motion. Ulnar collateral ligament (UCL) sprains have been linked to excessive elbow valgus and shoulder external rotation torques occurring during the late-cocking phase of throwing. Shoulder external rotation torque during the late arm-cocking phase and shoulder distraction forces during the deceleration phase contribute to tears of the labrum. Additionally, it is believed that the peak distraction force generated during the arm deceleration phase also contributes to SLAP tears and rotator cuff pathologies. Very little research has been done to directly examine the relationship between pitch velocity and the kinetic variables that contribute to injuries at the elbow and shoulder. Therefore, the purpose of this study was to examine the correlation of pitch velocity with elbow valgus torque, shoulder external rotation torque, and shoulder distraction force in a group of NCAA Division I collegiate baseball pitchers. Sixty-seven NCAA Division I college baseball pitchers were analyzed using highspeed motion analysis. Eight electronically synchronized high-speed (240 Hz) digital cameras tracked the movement of reflective markers placed over 26 anatomical landmarks on each participant in order to calculate the values of the kinetic variables examined. After warming up, participants threw fastballs off an indoor pitching mound towards a strike zone target. The average of the 3 highest velocity fastballs thrown for strikes was used for data analysis. The relationship between pitch velocity and peak elbow valgus torque, shoulder distraction force, and shoulder external rotation torque was analyzed using a Pearson\u27s correlation coefficient. A weak positive correlation was found between fastball velocity and shoulder distraction force (r = .26, p = .02) but there were no significant correlations between fastball velocity and elbow valgus torque (r = .20, p = .05) or fastball velocity and shoulder external rotation torque (r = .10, p = .22). The results of this study indicate that there is very little association between fastball velocity and several kinetic variables at the elbow and shoulder joints in Division I college baseball pitchers

Acceleration of phenological advance and warming with latitude over the past century.

In the Northern Hemisphere, springtime events are frequently reported as advancing more rapidly at higher latitudes, presumably due to an acceleration of warming with latitude. However, this assumption has not been investigated in an analytical framework that simultaneously examines acceleration of warming with latitude while accounting for variation in phenological time series characteristics that might also co-vary with latitude. We analyzed 743 phenological trend estimates spanning 86 years and 42.6 degrees of latitude in the Northern Hemisphere, as well as rates of Northern Hemisphere warming over the same period and latitudinal range. We detected significant patterns of co-variation in phenological time series characteristics that may confound estimates of the magnitude of variation in trends with latitude. Notably, shorter and more recent time series tended to produce the strongest phenological trends, and these also tended to be from higher latitude studies. However, accounting for such variation only slightly modified the relationship between rates of phenological advance and latitude, which was highly significant. Furthermore, warming has increased non-linearly with latitude over the past several decades, most strongly since 1998 and northward of 59°N latitude. The acceleration of warming with latitude has likely contributed to an acceleration of phenological advance along the same gradient

Comparative foraging ecology and social dynamics of caribou (Rangifer tarandus)

Thesis (Ph.D.) University of Alaska Fairbanks, 1995The Southern Alaska Peninsula Caribou (Rangifer tarandus) Herd (SAPCH) and its two sub-groups were the focus of a study addressing the hypotheses: (1) food limitation during winter caused a decline in the herd; and, (2) higher calf productivity within the Caribou River group than within the Black Hill group was related to greater forage availability on the seasonal ranges of the Caribou River group. Intense, systematic range and calving surveys in 1991 and 1992 supported the hypothesis of food limitation during winter, and indicated that greater calf production in the Caribou River group was related to earlier commencement of the season of plant growth and greater forage availability on the summer range of that group, coupled with earlier parturition among females of the Caribou River herd. In a comparative study involving the two SAPCH groups and the West Greenland Caribou Herd, daily variation in sizes of foraging groups, densities of caribou within feeding sites, distances between individuals within feeding sites, distances moved by foraging groups, and frequency of group movement was modeled using the following ecological parameters: predation risk, insect harassment (by mosquitos), range patchiness, feeding-site patchiness, feeding-site area, and range-wide density of caribou. Models revealed that intraseasonal social dynamics of foraging caribou were governed in most instances by patterns of forage availability and distribution across landscapes and within feeding sites, in some instances by insect harassment and social pressures, but in no instance by levels of predation risk inherent to the ranges on which they foraged. In a study of the interrelationships between characteristics of graminoids and intensity of grazing by caribou, vegetation on each of the Black Hill and Caribou River ranges was sampled and tested for responses to clipping. Biomass density (g/m\sp3) of forage, shoot density (#/m\sp2), and nutrient and mineral densities (g/m\sp3) and concentrations (g/100g tissue) correlated positively with use of sites by caribou. Productivity and responses to clipping were independent of previous use, but consistent within ranges. These results indicate that caribou are sensitive to local variation in forage quantity and quality, and preferentially use sites with higher returns of nutrients and minerals

Interactions between herbivory and warming in aboveground biomass production of arctic vegetation

<p>Abstract</p> <p>Background</p> <p>Many studies investigating the ecosystem effects of global climate change have focused on arctic ecosystems because the Arctic is expected to undergo the earliest and most pronounced changes in response to increasing global temperatures, and arctic ecosystems are considerably limited by low temperatures and permafrost. In these nutrient limited systems, a warmer climate is expected to increase plant biomass production, primarily through increases in shrubs over graminoids and forbs. But, the influence of vertebrate and invertebrate herbivores has been largely absent in studies investigating the effects of vegetation responses to climate change, despite the fact that herbivory can have a major influence on plant community composition, biomass and nutrient cycling. Here, we present results from a multi-annual field experiment investigating the effects of vertebrate herbivory on plant biomass response to simulated climate warming in arctic Greenland.</p> <p>Results</p> <p>The results after four years of treatments did not give any clear evidence of increased biomass of shrubs in response climate warming. Nor did our study indicate that vertebrate grazing mediated any increased domination of shrubs over other functional plant groups in response to warming. However, our results indicate an important role of insect outbreaks on aboveground biomass. Intense caterpillar foraging from a two-year outbreak of the moth <it>Eurois occulta </it>during two growing seasons may have concealed any treatment effects. However, there was some evidence suggesting that vertebrate herbivores constrain the biomass production of shrubs over graminoids and forbs.</p> <p>Conclusion</p> <p>Although inconclusive, our results were likely constrained by the overwhelming influence of an unexpected caterpillar outbreak on aboveground biomass. It is likely that the role of large vertebrate herbivores in vegetation response to warming will become more evident as this experiment proceeds and the plant community recovers from the caterpillar outbreak. Due to the greater influence of invertebrate herbivory in this study, it is advisable to consider both the effect of invertebrate and vertebrate herbivores in studies investigating climate change effects on plant communities.</p

Population response to climate change: linear vs. non-linear modeling approaches

BACKGROUND: Research on the ecological consequences of global climate change has elicited a growing interest in the use of time series analysis to investigate population dynamics in a changing climate. Here, we compare linear and non-linear models describing the contribution of climate to the density fluctuations of the population of wolves on Isle Royale, Michigan from 1959 to 1999. RESULTS: The non-linear self excitatory threshold autoregressive (SETAR) model revealed that, due to differences in the strength and nature of density dependence, relatively small and large populations may be differentially affected by future changes in climate. Both linear and non-linear models predict a decrease in the population of wolves with predicted changes in climate. CONCLUSIONS: Because specific predictions differed between linear and non-linear models, our study highlights the importance of using non-linear methods that allow the detection of non-linearity in the strength and nature of density dependence. Failure to adopt a non-linear approach to modelling population response to climate change, either exclusively or in addition to linear approaches, may compromise efforts to quantify ecological consequences of future warming

Vigilance and foraging behaviour of female caribou in relation to predation risk

Behaviour of female caribou (Rangifer tarandus) was investigated during the calving season on ranges in Alaska and West Greenland with the purpose of determining whether investment in vigilance behaviour differed between areas with and without natural predators of caribou. Female caribou in Alaska foraged in larger groups, displayed a higher rate of vigilance during feeding, spent less time feeding and, when lying, more often adopted a vigilant posture (with head up) than did female caribou in West Greenland. Moreover, a predation-vulnerable posture of lying down flat was observed in West Greenland but not in Alaska. Within Alaska, females with calves spent more time searching the environment than did those without calves. Finally, the amount of time individuals spent searching declined more gradually with group size in Alaska than in West Greenland, suggesting that what caribou perceive as a predator-safe threshold differs in the two areas. These results indicate that caribou, like several other species of ungulates, show behavioural adaptations to the risk of pr&eacute;dation which are relaxed when this risk is reduced

Paris'te Yahya Kemal

Taha Toros Arşivi, Dosya No: 182-Yahya Kemal Beyatlı. Not: Ekteki belgede Eric von Post'un "Bir Mayıs gecesinde" başlıklı yazısı bulunmaktadır.İstanbul Kalkınma Ajansı (TR10/14/YEN/0033) İstanbul Development Agency (TR10/14/YEN/0033

Sexual reproduction is more prevalent in continental landscapes in the expanding arctic shrub, Salix glauca

The recent expansion of arctic deciduous shrubs has been well documented across a range of habitats, but the phenomenon is not universal. Their spread is often associated with increases in temperature and other abiotic factors, while variation in habitat moisture and herbivory can mediate the location and rate of this rise in abundance. Much less is known about the mode of increase of arctic shrubs. For one such shrub, Salix glauca, we used microsatellite markers to assess the prevalence of clonal growth (i.e. vegetative spread) and sexual reproduction (i.e. recruitment from seed) at sites with maritime and continental climates and differing in the density of large herbivores. We sampled individuals in plots reflecting the spatial scale of expansion in locations where S. glauca recently increased in abundance. The 400 samples collected across the four sites comprised 310 genotypes. Though evidence of sexual recruitment was common across all sites, coastal sites contained both more and larger clonal genotypes. While we expected soil conditions would be influential, the factors that best predicted the likelihood of clonality, genet size and vascular plant cover, suggest the light environment is of primary importance. Furthermore, in spite of the large distances between sites, there was no suggestion of genetic differentiation into distinct populations. These results indicate that differences in climate and herbivory can influence not only where and how extensively deciduous shrubs spread, but how they are likely to do so. We suggest future research integrating how mode of increase is associated with the rate of spread will advance projections of change in arctic ecosystems

Audit Firm Affiliations with Companies Backdating Executive Stock Options

Several reports during 2005 -2007 questioned how over one-hundred pub-licly-traded companies had apparently backdated stock-option grants beginning in the 1990s. An analysis of the external audit firms affiliated with these companies revealed that these firms are dis-proportionally represented as compared to relative audit-market shares of all public companies. After controlling for industry-adjusted audit-market shares, statistically fewer backdating companies than expected used Arthur Andersen as their auditors. Overall, the results argue against the notion of audit firm involvement as a conduit for these transactions