Statistical analysis of thermospheric gravity waves from Fabry-Perot Interferometer measurements of atomic oxygen

Data from the Fabry-Perot Interferometers at KEOPS (Sweden), Sodankylä (Finland), and Svalbard (Norway), have been analysed for gravity wave activity on all the clear nights from 2000 to 2006. A total of 249 nights were available from KEOPS, 133 from Sodankylä and 185 from the Svalbard FPI. A Lomb-Scargle analysis was performed on each of these nights to identify the periods of any wave activity during the night. Comparisons between many nights of data allow the general characteristics of the waves that are present in the high latitude upper thermosphere to be determined. Comparisons were made between the different parameters: the atomic oxygen intensities, the thermospheric winds and temperatures, and for each parameter the distribution of frequencies of the waves was determined. No dependence on the number of waves on geomagnetic activity levels, or position in the solar cycle, was found. All the FPIs have had different detectors at various times, producing different time resolutions of the data, so comparisons between the different years, and between data from different sites, showed how the time resolution determines which waves are observed. In addition to the cutoff due to the Nyquist frequency, poor resolution observations significantly reduce the number of short-period waves (5 h) detected. Comparisons between the number of gravity waves detected at KEOPS and Sodankylä over all the seasons showed a similar proportion of waves to the number of nights used for both sites, as expected since the two sites are at similar latitudes and therefore locations with respect to the auroral oval, confirming this as a likely source region. Svalbard showed fewer waves with short periods than KEOPS data for a season when both had the same time resolution data. This gives a clear indication of the direction of flow of the gravity waves, and corroborates that the source is the auroral oval. This is because the energy is dissipated through heating in each cycle of a wave, therefore, over a given distance, short period waves lose more energy than long and dissipate before they reach their target

High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers(FPIs) to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesospherelower thermosphere (MLT) dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere

Operative mortality in resource-limited settings: the experience of Medecins Sans Frontieres in 13 countries.

OBJECTIVE: To determine operative mortality in surgical programs from resource-limited settings. DESIGN, SETTING, AND PARTICIPANTS: A retrospective cohort study of 17 surgical programs in 13 developing countries by 1 humanitarian organization, Médecins Sans Frontières, was performed between January 1, 2001, and December 31, 2008. Participants included patients undergoing surgical procedures. MAIN OUTCOME MEASURE: Operative mortality. Determinants of mortality were modeled using logistic regression. RESULTS: Between 2001 and 2008, 19,643 procedures were performed on 18,653 patients. Among these, 8329 procedures (42%) were emergent; 7933 (40%) were for obstetric-related pathology procedures and 2767 (14%) were trauma related. Operative mortality was 0.2% (31 deaths) and was associated with programs in conflict settings (adjusted odds ratio [AOR] = 4.6; P = .001), procedures performed under emergency conditions (AOR = 20.1; P = .004), abdominal surgical procedures (AOR = 3.4; P = .003), hysterectomy (AOR = 12.3; P = .001), and American Society of Anesthesiologists classifications of 3 to 5 (AOR = 20.2; P < .001). CONCLUSIONS: Surgical care can be provided safely in resource-limited settings with appropriate minimum standards and protocols. Studies on the burden of surgical disease in these populations are needed to improve service planning and delivery. Quality improvement programs are needed for the various stakeholders involved in surgical delivery in these settings

The MS Symptom and Impact Diary (MSSID): psychometric evaluation of a new instrument to measure the day to day impact of multiple sclerosis

OBJECTIVES: This study aimed to develop further a diary originally devised to measure the impact of multiple sclerosis (MS) as part of a cost utility study of beta interferon, and to evaluate its reliability, validity, and responsiveness in an outpatient sample of people with MS. METHODS: The original diary was further developed using qualitative and quantitative methods to ensure that it addressed the views of people with MS. The psychometric properties of the MS Symptom and Impact Diary (MSSID) were evaluated in a sample of 77 people who completed the MSSID daily for 12 weeks. Internal and test–retest reliability, discriminant and convergent validity, and responsiveness were assessed using traditional psychometric methods. RESULTS: The MSSID formed three, internally consistent scales that measured mobility, fatigue, and the overall impact of MS. The test–retest reliability of the mobility scale was adequate for individual comparisons (ICC.0.90) and the fatigue and overall impact scales were adequate for group comparisons (ICC.0.70). The MSSID was able to distinguish between clinical groups depending on clinical course, indoor ambulation status, and relapse status. It demonstrated associations with other single point instruments in the expected direction. Compared with single point instruments, its responsiveness was similar or better, especially in detecting short term improvements in functioning. CONCLUSIONS: The MSSID may provide a useful complement to currently available instruments to measure the outcomes of MS within clinical trials. Further research is needed to explore its feasibility in the context of a randomised controlled trial and its utility for clinicians

Implementing antiretroviral therapy in rural communities: the Lusikisiki model of decentralized HIV/AIDS care.

Health worker shortages are a major bottleneck to scaling up antiretroviral therapy (ART), particularly in rural areas. In Lusikisiki, a rural area of South Africa with a population of 150,000 serviced by 1 hospital and 12 clinics, Médecins Sans Frontières has been supporting a program to deliver human immunodeficiency virus (HIV) services through decentralization to primary health care clinics, task shifting (including nurse-initiated as opposed to physician-initiated treatment), and community support. This approach has allowed for a rapid scale-up of treatment with satisfactory outcomes. Although the general approach in South Africa is to provide ART through hospitals-which seriously limits access for many people, if not the majority of people-1-year outcomes in Lusikisiki are comparable in the clinics and hospital. The greater proximity and acceptability of services at the clinic level has led to a faster enrollment of people into treatment and better retention of patients in treatment (2% vs. 19% lost to follow-up). In all, 2200 people were receiving ART in Lusikisiki in 2006, which represents 95% coverage. Maintaining quality and coverage will require increased resource input from the public sector and full acceptance of creative approaches to implementation, including task shifting and community involvement

Nevirapine-Induced Heratotoxicity: Incidence, Risk Factors and Associated Mortality in a Primary Care ART Programme in South Africa

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