Injury rates and injury risk factors among federal bureau of investigation new agent trainees

<p>Abstract</p> <p>Background</p> <p>A one-year prospective examination of injury rates and injury risk factors was conducted in Federal Bureau of Investigation (FBI) new agent training.</p> <p>Methods</p> <p>Injury incidents were obtained from medical records and injury compensation forms. Potential injury risk factors were acquired from a lifestyle questionnaire and existing data at the FBI Academy.</p> <p>Results</p> <p>A total of 426 men and 105 women participated in the project. Thirty-five percent of men and 42% of women experienced one or more injuries during training. The injury incidence rate was 2.5 and 3.2 injuries/1,000 person-days for men and women, respectively (risk ratio (women/men) = 1.3, 95% confidence interval = 0.9-1.7). The activities most commonly associated with injuries (% of total) were defensive tactics training (58%), physical fitness training (20%), physical fitness testing (5%), and firearms training (3%). Among the men, higher injury risk was associated with older age, slower 300-meter sprint time, slower 1.5-mile run time, lower total points on the physical fitness test (PFT), lower self-rated physical activity, lower frequency of aerobic exercise, a prior upper or lower limb injury, and prior foot or knee pain that limited activity. Among the women higher injury risk was associated with slower 300-meter sprint time, slower 1.5-mile run time, lower total points on the PFT, and prior back pain that limited activity.</p> <p>Conclusion</p> <p>The results of this investigation supported those of a previous retrospective investigation emphasizing that lower fitness and self-reported pain limiting activity were associated with higher injury risk among FBI new agents.</p

Legacy of pre-disturbance spatial pattern determines early structural diversity following severe disturbance in mountain spruce forests in Czech Republic

Background Severe canopy-removing disturbances are native to many temperate forests and radically alter stand structure, but biotic legacies (surviving elements or patterns) can lend continuity to ecosystem function after such events. Poorly understood is the degree to which the structural complexity of an old-growth forest carries over to the next stand. We asked how predisturbance spatial pattern acts as a legacy to influence post-disturbance stand structure, and how this legacy influences the structural diversity within the early-seral stand. Methods Two stem-mapped one-hectare forest plots in the Czech Republic experienced a severe bark beetle outbreak, thus providing before-and-after data on spatial patterns in live and dead trees, crown projections, down logs, and herb cover. Results Post-disturbance stands were dominated by an advanced regeneration layer present before the disturbance. Both major species, Norway spruce (Picea abies) and rowan (Sorbus aucuparia), were strongly self-aggregated and also clustered to former canopy trees, predisturbance snags, stumps and logs, suggesting positive overstory to understory neighbourhood effects. Thus, although the disturbance dramatically reduced the stand’s height profile with ~100% mortality of the canopy layer, the spatial structure of post-disturbance stands still closely reflected the pre-disturbance structure. The former upper tree layer influenced advanced regeneration through microsite and light limitation. Under formerly dense canopies, regeneration density was high but relatively homogeneous in height; while in former small gaps with greater herb cover, regeneration density was lower but with greater heterogeneity in heights

Human meniscal proteoglycan metabolism in long-term tissue culture.

For the purpose of human meniscal allografting, menisci have been maintained viable in in vitro culture. The influence of long-term tissue culture on the extracellular matrix metabolism of the meniscus has been studied. Fetal calf serum (FCS) was used as a supplement for the growth factors necessary to maintain optimal meniscal cell metabolism. A series of semilunar cartilage samples was cultured under serum-free conditions since foreign proteins could be responsible for immunological problems after eventual allografting. The proteoglycan metabolism in human menisci cultured in FCS-supplemented and in serum-free culture media was compared. To rule out any influence of topographical variations in glycosaminoglycan (GAG) content on proteoglycan (PG) metabolism, GAG concentrations within the tissue were determined, and sulphate (35S) incorporation was studied in tissue samples with a comparable biochemical composition. Sulphate incorporation was preserved when 20% FCS was added to the nutrient medium. The meniscal tissue fibroblasts continued to produce 35S-PG during 4 weeks of culture. The PG molecules were shown to consist of PG-aggregates, monomers and a low molecular-weight PG population. Newly synthesized GAG consisted of approximately 55% chondroitin 4- and 6-sulphate and 33% dermatan sulphate. In the presence of serum, 35S incorporation in PG and in the PG-aggregate fraction significantly increased during the first 2 weeks and then decreased during the following 2 weeks of in vitro culture. Newly synthesized PG-aggregates were almost entirely accumulated in the tissue during these weeks. In the 3rd week the values for this parameter decreased slightly. 35S-PG synthesis dramatically declined after 4 weeks of in vitro culture. Catabolism probably resulted in increased proportions of 35S-PG in the incubation media. In the absence of serum, 35S-PG production also increased in the 2nd week of culture. However, 35S activity was almost exclusively found in small PG, and this material apparently diffused to the incubation media. Consequently, catabolism is higher, and the immobilization of 35S-PG is poor when FCS is not added to the culture media. Our findings suggest that menisci are maintained in viable condition and may serve for allografting at least during 2 weeks of tissue cultur

Structural origin of light emission in germanium quantum dots

We used a combination of optically-detected x-ray absorption spectroscopy with molecular dynamics simulations to explore the origins of light emission in small (5?nm to 9?nm) Ge nanoparticles. Two sets of nanoparticles were studied, with oxygen and hydrogen terminated surfaces. We show that optically-detected x-ray absorption spectroscopy shows sufficient sensitivity to reveal the different origins of light emission in these two sets of samples. We found that in oxygen terminated nanoparticles its the oxide-rich regions that are responsible for the light emission. In hydrogen terminated nanoparticles we established that structurally disordered Ge regions contribute to the luminescence. Using a combination of molecular dynamics simulations and optically-detected x-ray absorption spectroscopy we show that these disordered regions correspond to the disordered layer a few Å thick at the surface of the simulated nanoparticle