599 research outputs found

    The Effects of Severity of Losses of Well Clear on Minimum Operations Performance Standards End-To-End Verification and Validation Simulation Study for Integrating Unmanned Aircraft Systems into the National Airspace System Using Detect and Avoid Systems

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    As Unmanned Aircraft Systems (UAS) make their way to mainstream aviation operations within the National Airspace System (NAS), research efforts are underway to develop a safe and effective environment for their integration into the NAS. Detect and Avoid (DAA) systems are required to account for the lack of eyes in the sky due to having no human on-board the aircraft. The technique, results, and lessons learned from a detailed End-to-End Verification and Validation (E2-V2) simulation study of a DAA system representative of RTCA Special Committee(SC)-228s proposed Phase I DAA Minimum Operational Performance Standards (MOPS), based on specific test vectors and encounter cases, will be presented in this paper

    Potential for Induced Seismicity Related to the Northern California CO2 Reduction Project Pilot Test, Solano County, California

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    The objective of this technical report is to analyze the potential for induced seismicity due to a proposed small-scale CO{sub 2} injection project in the Montezuma Hills. We reviewed currently available public information, including 32 years of recorded seismic events, locations of mapped faults, and estimates of the stress state of the region. We also reviewed proprietary geological information acquired by Shell, including seismic reflection imaging in the area, and found that the data and interpretations used by Shell are appropriate and satisfactory for the purpose of this report. The closest known fault to the proposed injection site is the Kirby Hills Fault. It appears to be active, and microearthquakes as large as magnitude 3.7 have been associated with the fault near the site over the past 32 years. Most of these small events occurred 9-17 miles (15-28 km) below the surface, which is deep for this part of California. However, the geographic locations of the many events in the standard seismicity catalog for the area are subject to considerable uncertainty because of the lack of nearby seismic stations; so attributing the recorded earthquakes to motion along any specific fault is also uncertain. Nonetheless, the Kirby Hills Fault is the closest to the proposed injection site and is therefore our primary consideration for evaluating the potential seismic impacts, if any, from injection. Our planned installation of seismic monitoring stations near the site will greatly improve earthquake location accuracy. Shell seismic data also indicate two unnamed faults more than 3 miles east of the project site. These faults do not reach the surface as they are truncated by an unconformity at a depth of about 2,000 feet (610 m). The unconformity is identified as occurring during the Oligocene Epoch, 33.9-23.03 million years ago, which indicates that these faults are not currently active. Farther east are the Rio Vista Fault and Midland Fault at distances of about 6 miles (10 km) and 10 miles (16 km), respectively. These faults have been identified as active during the Quaternary (last 1.6 million years), but without evidence of displacement during the Holocene (the last 11,700 years). The stress state (both magnitude and direction) in the region is an important parameter in assessing earthquake potential. Although the available information regarding the stress state is limited in the area surrounding the injection well, the azimuth of the mean maximum horizontal stress is estimated at 41{sup o} and it is consistent with strike-slip faulting on the Kirby Hills Fault, unnamed fault segments to the south, and the Rio Vista Fault. However, there are large variations (uncertainty) in stress estimates, leading to low confidence in these conclusions regarding which fault segments are optimally oriented for potential slip induced by pressure changes. Uncertainty in the stress state can be substantially reduced by measurements planned when wells are drilled at the site. Injection of CO{sub 2} at about two miles depth will result in a reservoir fluid pressure increase, which is greatest at the well and decreases with distance from the well. After the injection stops, reservoir fluid pressures will decrease rapidly. Pressure changes have been predicted quantitatively by numerical simulation models of the injection. Based on these models, the pressure increase on the Kirby Hills Fault at its closest approach to the well due to the injection of 6,000 metric tons of CO{sub 2} would be a few pounds per square inch (psi), which is a tiny fraction of the natural pressure of approximately 5,000 psi at that depth. The likelihood of such a small pressure increase triggering a slip event is very small. It is even more unlikely that events would be induced at the significantly greater depths where most of the recorded earthquakes are concentrated, because it is unlikely that such a small pressure pulse would propagate downwards any appreciable distance. Therefore, in response to the specific question of the likelihood of the CO{sub 2} injection causing a magnitude 3.0 (or larger) event, this preliminary analysis suggests that no such induced or triggered events would be expected. However, it is possible that a fault, too small to be detected by the existing seismic data, yet sufficiently large to cause a magnitude 3 event, could exist in close proximity to the injection point where the pressure increase could cause slippage. However, the existence of such a fault would be detectable in the data planned for collection from the well prior to injection. We do note that natural earthquake events of up to 3.7 in magnitude have occurred in this area and would be expected to occur again regardless of the proposed CO{sub 2} injection

    Unmanned Aircraft Systems Detect and Avoid System: End-to-End Verification and Validation Simulation Study of Minimum Operations Performance Standards for Integrating Unmanned Aircraft into the National Airspace System

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    As Unmanned Aircraft Systems (UAS) make their way to mainstream aviation operations within the National Airspace System (NAS), research efforts are underway to develop a safe and effective environment for their integration into the NAS. Detect and Avoid (DAA) systems are required to account for the lack of "eyes in the sky" due to having no human on-board the aircraft. The technique, results, and lessons learned from a detailed End-to-End Verification and Validation (E2-V2) simulation study of a DAA system representative of RTCA SC-228's proposed Phase I DAA Minimum Operational Performance Standards (MOPS), based on specific test vectors and encounter cases, will be presented in this paper

    The potential impact of a cataract surgery programme on the care of orphans and vulnerable children in Swaziland

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    We aimed to evaluate the potential impact of a cataract surgery programme at the Good Shepherd Hospital, Siteki, Swaziland, on the care of orphans and vulnerable children in Swaziland. We studied consecutive patients aged 50 years and older undergoing surgery for age-related cataract who reported having children living in their household. Of 131 subjects recruited, 65 (49.6%) were the primary caregivers for the child(ren) in their household. Visual acuities measured 2 weeks after surgery significantly improved. Four weeks after surgery, there was a sizable increase in the proportions of subjects who were able to undertake self-care activities, attend to activities of daily living, undertake income-generating activities and care for children. Cataract surgery on elderly visually impaired patients has the potential to impact positively on the care of orphans and vulnerable children

    'Pregnancy comes accidentally - like it did with me': reproductive decisions among women on ART and their partners in rural Uganda

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    <p>Abstract</p> <p>Background</p> <p>As highly active antiretroviral therapy (ART) restores health, fertility and sexual activity among HIV-infected adults, understanding how ART influences reproductive desires and decisions could inform interventions to reduce sexual and vertical HIV transmission risk.</p> <p>Methods</p> <p>We performed a qualitative sub-study among a Ugandan cohort of 1,000 adults on ART with four purposively selected categories of participants: pregnant, not pregnant, delivered, and aborted. In-depth interviews examined relationships between HIV, ART and pregnancy, desire for children, perceived risks and benefits of pregnancy, decision-making regarding reproduction and family planning (FP) among 29 women and 16 male partners. Analysis focused on dominant explanations for emerging themes across and within participant groups.</p> <p>Results</p> <p>Among those who had conceived, most couples stated that their pregnancy was unintentional, and often occurred because they believed that they were infertile due to HIV. Perceived reasons for women not getting pregnant included: ill health (included HIV infection and ART), having enough children, financial constraints, fear of mother-to-child HIV transmission or transmission to partner, death of a child, and health education. Most women reported FP experiences with condoms and hormonal injections only. Men had limited FP information apart from condoms.</p> <p>Conclusions</p> <p>Counselling at ART initiation may not be sufficient to enable women who do not desire children to adopt relevant family planning practices. On-going reproductive health education and FP services, with emphasis on the restoration of fertility after ART initiation, should be integrated into ART programs for men and women.</p

    Differential neuromuscular training effects onACL injury risk factors in"high-risk" versus "low-risk" athletes

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    <p>Abstract</p> <p>Background</p> <p>Neuromuscular training may reduce risk factors that contribute to ACL injury incidence in female athletes. Multi-component, ACL injury prevention training programs can be time and labor intensive, which may ultimately limit training program utilization or compliance. The purpose of this study was to determine the effect of neuromuscular training on those classified as "high-risk" compared to those classified as "low-risk." The hypothesis was that high-risk athletes would decrease knee abduction moments while low-risk and control athletes would not show measurable changes.</p> <p>Methods</p> <p>Eighteen high school female athletes participated in neuromuscular training 3×/week over a 7-week period. Knee kinematics and kinetics were measured during a drop vertical jump (DVJ) test at pre/post training. External knee abduction moments were calculated using inverse dynamics. Logistic regression indicated maximal sensitivity and specificity for prediction of ACL injury risk using external knee abduction (25.25 Nm cutoff) during a DVJ. Based on these data, 12 study subjects (and 4 controls) were grouped into the high-risk (knee abduction moment >25.25 Nm) and 6 subjects (and 7 controls) were grouped into the low-risk (knee abduction <25.25 Nm) categories using mean right and left leg knee abduction moments. A mixed design repeated measures ANOVA was used to determine differences between athletes categorized as high or low-risk.</p> <p>Results</p> <p>Athletes classified as high-risk decreased their knee abduction moments by 13% following training (Dominant pre: 39.9 ± 15.8 Nm to 34.6 ± 9.6 Nm; Non-dominant pre: 37.1 ± 9.2 to 32.4 ± 10.7 Nm; p = 0.033 training X risk factor interaction). Athletes grouped into the low-risk category did not change their abduction moments following training (p > 0.05). Control subjects classified as either high or low-risk also did not significantly change from pre to post-testing.</p> <p>Conclusion</p> <p>These results indicate that "high-risk" female athletes decreased the magnitude of the previously identified risk factor to ACL injury following neuromuscular training. However, the mean values for the high-risk subjects were not reduced to levels similar to low-risk group following training. Targeting female athletes who demonstrate high-risk knee abduction loads during dynamic tasks may improve efficacy of neuromuscular training. Yet, increased training volume or more specific techniques may be necessary for high-risk athletes to substantially decrease ACL injury risk.</p

    Socioeconomic predictors and consequences of depression among primary care attenders with non-communicable diseases in the Western Cape, South Africa:Cohort study within a randomised trial

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    Background: Socioeconomic predictors and consequences of depression and its treatment were investigated in 4393 adults with specified non-communicable diseases attending 38 public sector primary care clinics in the Eden and Overberg districts of the Western Cape, South Africa.   Methods: Participants were interviewed at baseline in 2011 and 14 months later, as part of a randomised controlled trial of a guideline-based intervention to improve diagnosis and management of chronic diseases. The 10-item Center for Epidemiologic Studies Depression Scale (CESD-10) was used to assess depression symptoms, with higher scores representing more depressed mood. Results: Higher CESD-10 scores at baseline were independently associated with being less educated (p=0.004) and having lower income (p=0.003). CESD-10 scores at follow-up were higher in participants with less education (p=0.010) or receiving welfare grants (p=0.007) independent of their baseline scores. Participants with CESD-10 scores of 10 or more at baseline (56% of all participants) had 25% higher odds of being unemployed at follow-up (p=0.016), independently of baseline CESD-10 score and treatment status. Among participants with baseline CESD-10 scores of 10 or more, antidepressant medication at baseline was independently more likely in participants who had more education (p=0.002), higher income (p<0.001), or were unemployed (p=0.001). Antidepressant medication at follow up was independently more likely in participants with higher income (p=0.023), and in clinics with better access to pharmacists (p=0.053) and off-site drug delivery (p=0.013).  Conclusions: Socioeconomic disadvantage appears to be both a cause and consequence of depression, and may also be a barrier to treatment. There are opportunities for improving the prevention, diagnosis and treatment of depression in primary care in inequitable middle income countries like South Africa.  Trial registration: The trial is registered with Current Controlled Trials (ISRCTN20283604) and the Office for Human Research Protections Database (IRB00001938, FWA00001637)
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