Effects of Pubertal Growth Variation on Knee Mechanics During Walking in Female and Male Adolescents

Introduction: Puberty substantially alters the body\u27s mechanical properties, neuromuscular control, and sex differences therein, likely contributing to increased, sex-biased knee injury risk during adolescence. Female adolescents have higher risk for knee injuries than male adolescents of similar age engaging in similar physical activities, and much research has investigated sex differences in mechanical risk factors. However, few studies address the considerable variation in pubertal growth (timing, pace), knee mechanics, and injury susceptibility within sexes, or the impact of such growth variation on mechanical injury risk. Objectives: The present study tested for effects of variation in pubertal growth on established mechanical knee injury risk factors, examining relationships between and within sexes. Methods: Pubertal growth indices describing variation in the timing and rate of pubertal growth were developed using principal component analysis and auxological data from serial stature measurements. Linear mixed models were applied to evaluate relationships between these indices and knee mechanics during walking in a sample of adolescents. Results: Later developing female adolescents with slower pubertal growth had higher extension moments throughout stance, whereas earlier developers had higher valgus knee angles and moments. In male adolescents, faster and later growth were related to higher extension moments throughout gait. In both sexes, faster growers had higher internal rotation moments at foot-strike. Conclusions: Pubertal growth variation has important effects on mechanical knee injury risk in adolescence, affecting females and males differently. Earlier developing females exhibit greater injury risk via frontal plane factors, whereas later/faster developing males have elevated risk via sagittal plane mechanisms

Observations of Long-tailed Weasel, Mustela frenata, Hunting Behavior in Central West Virginia

Using infrared video-surveillance systems during 1999–2000, we observed attempts by two individual Long-tailed Weasels (Mustela frenata) to depredate female Ruffed Grouse (Bonasa umbellus) and their clutch of eggs. Neither female was captured despite Long-tailed Weasel attacks on multiple nights, but all eggs from one nest were either consumed or cached over a two-night period. Although Long-tailed Weasels have been shown to return quickly to areas of abundant prey, return visit behavior to locations where weasels were unsuccessful or only partially successful are poorly described

Observations of Long-tailed Weasel, Mustela frenata, Hunting Behavior in Central West Virginia

Using infrared video-surveillance systems during 1999–2000, we observed attempts by two individual Long-tailed Weasels (Mustela frenata) to depredate female Ruffed Grouse (Bonasa umbellus) and their clutch of eggs. Neither female was captured despite Long-tailed Weasel attacks on multiple nights, but all eggs from one nest were either consumed or cached over a two-night period. Although Long-tailed Weasels have been shown to return quickly to areas of abundant prey, return visit behavior to locations where weasels were unsuccessful or only partially successful are poorly described

Necklace-Type Transmitter Attachment Method for Ruffed Grouse Chicks

Although methodologies to obtain cause-specific mortality and survival information for adult ruffed grouse (Bonasa umbellus) are well documented, procedures for determining similar parameters are lacking for grouse chicks. Mortality among grouse chicks is believed highest during the first few weeks posthatch. During 1999-2002, we equipped ruffed grouse chicks (n = 97) from 33 separate broods, ≤ 4-days-old with radio transmitters to assess the efficacy of transmitters and to examine survival/mortality. Further, we observed that grouse chicks retained transmitters (100%) until recapture or mortality. Handling time was limited because transmitter attachment took only a few minutes per brood. We observed mortality fates for 91% of radio-collared chicks. Therefore, because of the non-intrusive nature, field application, and retention of necklace-style transmitters employed in this study, this method may provide a desirable alternative to assessing survival/mortality among ruffed grouse chicks

Force distributions in a triangular lattice of rigid bars

We study the uniformly weighted ensemble of force balanced configurations on a triangular network of nontensile contact forces. For periodic boundary conditions corresponding to isotropic compressive stress, we find that the probability distribution for single-contact forces decays faster than exponentially. This super-exponential decay persists in lattices diluted to the rigidity percolation threshold. On the other hand, for anisotropic imposed stresses, a broader tail emerges in the force distribution, becoming a pure exponential in the limit of infinite lattice size and infinitely strong anisotropy.Comment: 11 pages, 17 figures Minor text revisions; added references and acknowledgmen

Geochemical Reconstruction of Late Holocene Drainage and Mixing in Kluane Lake, Yukon Territory

The level of Kluane Lake in southwest Yukon Territory, Canada, has fluctuated tens of metres during the late Holocene. Contributions of sediment from different watersheds in the basin over the past 5,000 years were inferred from the elemental geochemistry of Kluane Lake sediment cores. Elements associated with organic material and oxyhydroxides were used to reconstruct redox fluctuations in the hypolimnion of the lake. The data reveal complex relationships between climate and river discharge during the late Holocene. A period of influx of Duke River sediment coincides with a relatively warm climate around 1,300 years BP. Discharge of Slims River into Kluane Lake occurred when Kaskawulsh Glacier advanced to the present drainage divide separating flow to the Pacific Ocean via Kaskawulsh and Alsek rivers from flow to Bering Sea via tributaries of Yukon River. During periods when neither Duke nor Slims river discharged into Kluane Lake, the level of the lake was low and stable thermal stratification developed, with anoxic and eventually euxinic conditions in the hypolimnion

Timing and Cause of Water Level Fluctuations in Kluane Lake, Yukon Territory, Over the Past 5000 Years

We reconstructed late Holocene fluctuations of Kluane Lake in Yukon Territory from variations in bulk physical properties and carbon and nitrogen elemental and isotopic abundances in nine sediment cores. Fluctuations of Kluane Lake in the past were controlled by changes in climate and glaciers, which affected inflow of Slims and Duke rivers, the two largest sources of water flowing into the lake. Kluane Lake fluctuated within a narrow range, at levels about 25 m below the present datum, from about 5000 to 1300 cal yr BP. Low lake levels during this interval are probably due to southerly drainage of Kluane Lake to the Pacific Ocean, opposite the present northerly drainage to Bering Sea. Slims River, which today is the largest contributor of water to Kluane Lake, only rarely flowed into the lake during the period 5000 to 1300 cal yr BP. The lake rose 7–12 m between 1300 and 900 cal yr BP, reached its present level around AD 1650, and within a few decades had risen an additional 12 m. Shortly thereafter, the lake established a northern outlet and fell to near its present level

Tendinosis develops from age- and oxygen tension-dependent modulation of Rac1 activity.

Age-related tendon degeneration (tendinosis) is characterized by a phenotypic change in which tenocytes display characteristics of fibrochondrocytes and mineralized fibrochondrocytes. As tendon degeneration has been noted in vivo in areas of decreased tendon vascularity, we hypothesized that hypoxia is responsible for the development of the tendinosis phenotype, and that these effects are more pronounced in aged tenocytes. Hypoxic (1% O2 ) culture of aged, tendinotic, and young human tenocytes resulted in a mineralized fibrochondrocyte phenotype in aged tenocytes, and a fibrochondrocyte phenotype in young and tendinotic tenocytes. Investigation of the molecular mechanism responsible for this phenotype change revealed that the fibrochondrocyte phenotype in aged tenocytes occurs with decreased Rac1 activity in response to hypoxia. In young hypoxic tenocytes, however, the fibrochondrocyte phenotype occurs with concomitant decreased Rac1 activity coupled with increased RhoA activity. Using pharmacologic and adenoviral manipulation, we confirmed that these hypoxic effects on the tenocyte phenotype are linked directly to the activity of RhoA/Rac1 GTPase in in vitro human cell culture and tendon explants. These results demonstrate that hypoxia drives tenocyte phenotypic changes, and provide a molecular insight into the development of human tendinosis that occurs with aging

Examples of Collaboration Between Psychologists and Clergy

Some psychologists may be interested in working collaboratively with clergy and yet may not know where to start. What kinds of collaborative projects are possible? A qualitative analysis of 77 narratives offered by psychologists and clergy involved in collaboration revealed that collaboration between psychologists and clergy currently takes place in at least four contexts: mental health services, parish life, community concerns, and academics. Reported obstacles to collaboration are also described. Essential attitudes for psychologists interested in collaborating with clergy include respecting clergy as professionals, willingness to venture out from traditional professional settings, and exploring innovative collaborative possibilities