543 research outputs found
Site assessment of Douglas Shoal ship grounding in the Great Barrier Reef
The bulk carrier Shen Neng 1 ran aground on Douglas Shoal in the Great Barrier Reef Marine Park in April 2010. At over 40 hectares, this is the largest ship grounding scar known in the Great Barrier Reef, and possibly the largest reef-related grounding in the world. Challenges for assessment of the site included its large scale and the remote nature of Douglas Shoal coupled with its high exposure to wind, wave conditions and fauna that may pose safety hazards. Marine surveys used multiple and novel methods including sediment sampling combined with visual and acoustic survey techniques
Biomechanical risk factors for lower extremity stress fracture
Objectives: Stress fracture injuries disproportionately affect athletes and military service members and little is known about the modifiable biomechanical risk factors associated with these injuries. The purpose of this study was to prospectively examine the association between neuromuscular and biomechanical factors upon entry to military service and the subsequent incidence of lower-extremity stress fracture injury during four years of follow-up. Methods: We analyzed data from the JUMP-ACL cohort, an existing prospective cohort study of military cadets. JUMP-ACL conducted detailed motion analysis during a jump landing task at the initiation of each subject’s military career. We limited our analyses to the class years 2009-2013 (i.e., subjects who completed baseline testing in 2005-2008). There were 1895 subjects available for analysis. Fifty-two subjects reported a history of stress fracture at baseline and were excluded from further analysis leaving 1843 subjects. Incident lower extremity-stress fracture cases were identified through the Defense Medical Surveillance System and the Cadet Injury and Illness Tracking System during the follow-up period. The electronic medical records of each potential incident case were reviewed and each case was confirmed by an adjudication committee consisting of two sports medicine fellowship trained orthopaedic surgeons. The primary outcome of interest was the incidence rate of lower-extremity stress fracture during the follow-up period. The association between incident stress fracture and sagittal, frontal, and transverse plane hip and knee kinematics during the jump-landing task were examined at initial contact (IC), 15%(T15), 50%(T50), 85%(T85) and 100%(T100) of stance phase. Descriptive plots of all biomechanical variables along with 95% confidence intervals (CI) were generated during the stance phase of the jump landing task. Univariate and multivariable Poisson regression models were used to estimate the association between baseline biomechanical factors and the incidence rate of lower-extremity stress fracture during follow-up. Results: Overall, 94 (5.1%, 95%CI: 4.14, 6.21) subjects sustained an incident stress fracture during the follow-up period. The incidence rate for stress fracture injuries among females was nearly three times greater when compared to males (IRR=2.86, 95%CI: 1.88, 4.34, p<0.001). Compared to those with greater than 5° of knee valgus, subjects with neutral or varus knee alignment experienced incidence rates for stress fracture that were 43%-53% lower at IC (IRR=0.57, 95%CI: 0.29, 1.11, p=0.10), T50 (IRR=0.47, 95%CI=0.23, 1.00, p=0.05), and T85 (IRR=0.53, 95%CI: 0.29, 0.98, p=0.04). Subjects with greater than 5° of internal knee rotation exhibited rates for stress fracture that were 2-4 times higher at T15 (IRR=2.31, 95%CI: 1.01, 5.27, p=0.05), T50 (IRR=3.98, 95%CI: 0.99, 16.00, p=0.05), and T85 (IRR=2.31, 95%CI: 0.86, 6.23, p=0.10), when compared to those with neutral or external knee rotation alignment. Conclusion: Several potentially modifiable biomechanical factors at the time of entry into military service appear to be associated with the subsequent rate of stress fracture. It is possible that injury prevention programs targeted to address these biomechanical movement patterns may reduce the risk of stress fracture injury in athletes and military service members
Performance of a Neutron Polarimeter to Measure the Electric Form Factor of the Neutron
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Landing Error Scoring System (LESS) Items are Associated with the Incidence Rate of Lower Extremity Stress Fracture
Objectives: Lower-extremity stress fracture injuries are a major cause of morbidity in physically active populations. The ability to efficiently screen for modifiable risk factors associated with injury is critical in developing and implementing effective injury prevention programs. The purpose of this study was to determine if baseline Landing Error Scoring System (LESS) scores were associated with the incidence rate of lower-extremity stress fracture during four years of follow-up. Methods: To accomplish this objective we conducted a prospective cohort study at a US Service Academy. A total of 1772 eligible subjects with complete baseline data and no history of lower-extremity stress fracture were included in this study. At baseline we conducted motion analysis during a jump landing task using the LESS. Incident lower-extremity stress fracture cases were identified during the four year follow-up period using the injury surveillance systems at our institution. The primary outcome of interest was the incidence rate of lower-extremity stress fracture during follow-up. The electronic medical records of each potential incident case were reviewed and case status was determined by an adjudication committee consisting of two sports medicine fellowship-trained orthopaedic surgeons who were blinded to baseline LESS data. The association between baseline LESS scores and the incidence rate of lower-extremity stress fracture was examined for total LESS score and for each individual LESS item. Univariate and multivariable Poisson regression models were used to estimate the association between baseline LESS scores and the incidence rate of lower-extremity stress fracture during follow-up. Results: During the follow-up period, 94 incident lower-extremity stress fractures were documented in the study cohort and the cumulative incidence of stress fracture was 5.3% (95%CI: 4.3%, 6.5%). In univariate analyses total LESS score at baseline was associated with the incidence rate of lower-extremity stress fracture during follow-up. For every additional movement error documented at baseline there was a 15% increase in the incidence rate of lower-extremity stress fracture during follow-up (IRR=1.15; 95%CI: 1.02, 1.31, p=0.025). Based on univariate analyses, several individual LESS items at baseline were also associated with the incidence rate of stress fracture during follow-up. Ankle flexion at initial contact (p=0.055), stance width at initial contact (p=0.026), asymmetrical landing at initial contact (p=0.003), trunk flexion at initial contact (p=0.036), and overall impression (p=0.021) were significantly associated with the incidence rate of stress fracture. In multivariable analyses controlling for sex and year of entry into the cohort, subjects who consistently landed flat-footed or heel-to-toe were 2.33 times (IRR=2.33; 95%CI: 1.36, 3.97, p=0.002) more likely to sustain a lower-extremity stress fracture during follow-up. Similarly, subjects who consistently demonstrated asymmetric landing at initial contact were 2.53 times (IRR=2.53; 95%CI: 1.34, 4.74, p=0.004) more likely to sustain a stress fracture during follow-up. Conclusion: These data suggest that specific LESS items may be predictive of lower-extremity stress fracture risk and may be helpful in injury screening and prevention
Calibration of a Proton Polarimeter
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Abundances of the elements in the solar system
A review of the abundances and condensation temperatures of the elements and
their nuclides in the solar nebula and in chondritic meteorites. Abundances of
the elements in some neighboring stars are also discussed.Comment: 42 pages, 11 tables, 8 figures, chapter, In Landolt- B\"ornstein, New
Series, Vol. VI/4B, Chap. 4.4, J.E. Tr\"umper (ed.), Berlin, Heidelberg, New
York: Springer-Verlag, p. 560-63
Calibration of a Neutron Polarimeter
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Expanding the proteome of an RNA virus by phosphorylation of an intrinsically disordered viral protein
The human proteome contains myriad intrinsically disordered proteins. Within intrinsically disordered proteins, polyproline-II motifs are often located near sites of phosphorylation. Wehave used an unconventional experimental paradigm to discover that phosphorylation by protein kinase A (PKA) occurs in the intrinsically disordered domain of hepatitis C virus nonstructural protein 5A (NS5A) on Thr-2332 near one of its polyproline-II motifs. Phosphorylation shifts the conformational ensemble of the NS5A intrinsically disordered domain to a state that permits detection of the polyproline motif by using 15N-, 13C-based multidimensional NMR spectroscopy. PKA-dependent proline resonances were lost in the presence of the Src homology 3 domain of c-Src, consistent with formation of a complex. Changing Thr-2332 to alanine in hepatitisCvirus genotype 1b reduced the steady-state level of RNA by 10-fold; this change was lethal for genotype 2a. The lethal phenotype could be rescued by changing Thr-2332 to glutamic acid, a phosphomimetic substitution. Immunofluorescence and transmission electron microscopy showed that the inability to produce Thr(P)-2332-NS5A caused loss of integrity of the virus-induced membranous web/replication organelle. An even more extreme phenotype was observed in the presence of small molecule inhibitors of PKA. We conclude that the PKA-phosphorylated form of NS5A exhibits unique structure and function relative to the unphosphorylated protein. We suggest that post-translational modification of viral proteins containing intrinsic disorder may be a general mechanism to expand the viral proteome without a corresponding expansion of the genome
Inequality of opportunity in the land of opportunities : 1968-2001
We measure inequality of opportunity for earnings acquisition in the U.S. between 1968 and 2001. Following recent theories of social justice, earnings determinants are divided into two parts: Circumstances, which are characteristics outside individual control and effort representing factors impacting earnings but under individuals’ responsibility. Equality of opportunity requires that inequality of circumstances must be corrected while differences of effort must remain unaltered. Circumstances are represented by parental education and occupation, ethnic origin, place of birth and age. Effort is modeled with schooling choices and labour supply decisions. Using the PSID from 1968 to 2001, we provide two alternative assessments of inequality of opportunity using counterfactual distributions. The statistical framework is semi-parametric and builds on duration models. Finally, we conclude that inequality of opportunity represents between 20 and 43% of earnings inequality, but decreases all over the period reaching around 18% in 2001
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
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