53 research outputs found
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Polar Ice Accumulation from Volcanically Induced Transient Atmospheres on the Moon
Water ice exists at the lunar poles, but its origin, abundance, and distribution are not well understood. One potential source of water to the poles is the volcanic outgassing of volatiles from the lunar interior and subsequent condensation of erupted water vapor as surface ice. We investigate whether volcanic outgassing is a viable source for the accumulation of lunar polar water ice. We construct a model that accounts for volcanic outgassing, atmospheric escape to space, and surface ice accumulation over the period of peak lunar volcanic activity (4–2 Ga) and map the resulting water ice distribution and abundance using current surface temperature data from the Lunar Reconnaissance Orbiter. Our model suggests that ∼41% of the total H2O mass erupted over this period could have condensed as ice in the polar regions, with thicknesses up to several hundreds of meters. The south pole accumulates roughly twice the ice mass of the north, and the southern deposits are thicker. Typical modeled eruptions generate collisional atmospheres with lifetimes of ∼2500 yr. However, these atmospheres are episodic and generally do not persist between eruptions. Roughly 15% of an atmosphere's water vapor mass forms a frost on the lunar nightside, while the transient atmosphere persists. Our work suggests that the volcanically active period of the early Moon would have been punctuated by short-lived, collisional atmospheres that enabled the efficient sequestration of large quantities (8.2 × 1015 kg) of water ice at the poles and the temporary diurnal availability of water ice and vapor at all latitudes.
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Possible Atmospheric Water Vapor Contribution from Martian Swiss Cheese Terrain
Mars's south polar residual cap (SPRC) is a several-meters-thick CO2 ice cap with a variety of features, including quasi-circular depressions known as "Swiss cheese" that may expose underlying water ice. Swiss cheese pits have been suggested as a source for the observation of unusually high water vapor during the southern summer of Mars Year (MY) 8 (1969). To evaluate this hypothesis, we map the current extent of Swiss cheese pits to estimate the contribution to atmospheric water vapor from sublimation from the pits. We use data from the Mars Reconnaissance Orbiter Context Camera to map individual features and use the Mars Climate Sounder to obtain surface temperatures to estimate areas of exposed water ice to infer the amount of water vapor sublimated under typical south polar summer atmospheric conditions. We find that there is a negligible impact on atmospheric water vapor from sublimation with the current coverage and temperatures of Swiss cheese terrain (0.2% of the SPRC at an average of ∼161 K). At current typical temperatures, complete removal of residual CO2 from 99% of the SPRC would be required to sublimate enough water vapor to reproduce the MY 8 observation. However, a modest increase in temperature (∼20 K) could lead to a dramatic increase in sublimation rate, such that only water ice over 2.6% of the SPRC area would recreate the MY 8 observation. >180 K surface water ice has been observed on Mars, but such temperatures are likely transient at the south pole over the past ∼30 Mars years.
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The Putative Cerean Exosphere
The ice-rich crust of dwarf planet 1 Ceres is the source of a tenuous water exosphere, and the behavior of thisputative exosphere is investigated with model calculations. Outgassing water molecules seasonally condensearound the winter pole in an optically thin layer
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Spatial Distribution and Thermal Diversity of Surface Volatile Cold Traps at the Lunar Poles
The polar regions of the Moon host some of the most extreme low temperatures in the inner solar system due to its low obliquity, lack of atmosphere, and topographic relief. Some of these regions are already confirmed to host water ice. Proposed sources of water and other volatiles include lunar volcanic outgassing, solar wind, and comet impacts. Each of these possible sources would carry a potentially identifiable compositional signature beyond water. Determining the dominant sources of lunar volatiles, therefore, requires assessing the long-term thermal stability of an array of compounds. We present results of mapping the surface thermal stability locations of multiple key volatiles, including water, from the Diviner Lunar Radiometer data from 60° to 90° latitude in both hemispheres. We find the annual maximum temperature for each pixel of interest in the map (∼300 m) to determine which volatiles of interest would be stable there. We report on the thermal stability area of each volatile, as well as the geologic context in some cases. We find that while the thermal stability area for volatiles is larger in the south pole generally, both the north pole and south pole host areas where potential tracer volatiles from lunar volcanism, solar wind, and cometary impacts would be thermally stable for billions of years if such volatiles were ever delivered. We find several areas equatorward of ∼80° on the lunar nearside that could host water ice, where future missions could potentially access volatile deposits in order to place constraints on water delivery to the Moon.
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Randomized controlled trials in pediatric complementary and alternative medicine: Where can they be found?
BACKGROUND: The safety and effectiveness of CAM interventions are of great relevance to pediatric health care providers. The objective of this study is to identify sources of reported randomized controlled trials (RCTs) in the field of pediatric complementary and alternative medicine (CAM). METHODS: Reports of RCTs were identified by searching Medline and 12 additional bibliographic databases and by reviewing the reference lists of previously identified pediatric CAM systematic reviews. RESULTS: We identified 908 reports of RCTs that included children under 18 and investigated a CAM therapy. Since 1965, there has been a steady growth in the number of these trials that are being published. The four journals that published the most reported RCTs are The American Journal of Clinical Nutrition, Pediatrics, Journal of Pediatrics, and Lancet. Medline, CAB Health, and Embase were the best database sources for identifying these studies; they indexed 93.2%, 58.4% and 42.2 % respectively of the journals publishing reports of pediatric CAM RCTs. CONCLUSIONS: Those working or interested in the field of pediatric CAM should routinely search Medline, CAB Health and Embase for literature in the field. The four core journals identified above should be included in their collection
Toward optimal implementation of cancer prevention and control programs in public health: A study protocol on mis-implementation
Abstract Background Much of the cancer burden in the USA is preventable, through application of existing knowledge. State-level funders and public health practitioners are in ideal positions to affect programs and policies related to cancer control. Mis-implementation refers to ending effective programs and policies prematurely or continuing ineffective ones. Greater attention to mis-implementation should lead to use of effective interventions and more efficient expenditure of resources, which in the long term, will lead to more positive cancer outcomes. Methods This is a three-phase study that takes a comprehensive approach, leading to the elucidation of tactics for addressing mis-implementation. Phase 1: We assess the extent to which mis-implementation is occurring among state cancer control programs in public health. This initial phase will involve a survey of 800 practitioners representing all states. The programs represented will span the full continuum of cancer control, from primary prevention to survivorship. Phase 2: Using data from phase 1 to identify organizations in which mis-implementation is particularly high or low, the team will conduct eight comparative case studies to get a richer understanding of mis-implementation and to understand contextual differences. These case studies will highlight lessons learned about mis-implementation and identify hypothesized drivers. Phase 3: Agent-based modeling will be used to identify dynamic interactions between individual capacity, organizational capacity, use of evidence, funding, and external factors driving mis-implementation. The team will then translate and disseminate findings from phases 1 to 3 to practitioners and practice-related stakeholders to support the reduction of mis-implementation. Discussion This study is innovative and significant because it will (1) be the first to refine and further develop reliable and valid measures of mis-implementation of public health programs; (2) bring together a strong, transdisciplinary team with significant expertise in practice-based research; (3) use agent-based modeling to address cancer control implementation; and (4) use a participatory, evidence-based, stakeholder-driven approach that will identify key leverage points for addressing mis-implementation among state public health programs. This research is expected to provide replicable computational simulation models that can identify leverage points and public health system dynamics to reduce mis-implementation in cancer control and may be of interest to other health areas
Complementary and alternative medicine use among US Navy and Marine Corps personnel
<p>Abstract</p> <p>Background</p> <p>Recently, numerous studies have revealed an increase in complementary and alternative medicine (CAM) use in US civilian populations. In contrast, few studies have examined CAM use within military populations, which have ready access to conventional medicine. Currently, the prevalence and impact of CAM use in US military populations remains unknown.</p> <p>Methods</p> <p>To investigate CAM use in US Navy and Marine Corps personnel, the authors surveyed a stratified random sample of 5,000 active duty and Reserve/National Guard members between December 2000 and July 2002. Chi-square tests and multivariable logistic regression were used to assess univariate associations and adjusted odds of CAM use in this population.</p> <p>Results and discussion</p> <p>Of 3,683 service members contacted, 1,446 (39.3%) returned a questionnaire and 1,305 gave complete demographic and survey data suitable for study. Among respondents, more than 37% reported using at least one CAM therapy during the past year. Herbal therapies were among the most commonly reported (15.9%). Most respondents (69.8%) reported their health as being very good or excellent. Modeling revealed that CAM use was most common among personnel who were women, white, and officers. Higher levels of recent physical pain and lower levels of satisfaction with conventional medical care were significantly associated with increased odds of reporting CAM use.</p> <p>Conclusion</p> <p>These data suggest that CAM use is prevalent in the US military and consistent with patterns in other US civilian populations. Because there is much to be learned about CAM use along with allopathic therapy, US military medical professionals should record CAM therapies when collecting medical history data.</p
Appropriateness of acute admissions and last in-patient day for patients with long term neurological conditions
<p>Abstract</p> <p>Background</p> <p>To examine the appropriateness of admissions and in-patient stay for patients with long term neurological conditions (LTNCs). To identify variables predictive of appropriateness and explore management alternatives.</p> <p>Methods</p> <p>Adults admitted as acute patients to Derby Hospitals NHS Foundation Trust (England). Data were collected prospectively and examined by a multi-disciplinary expert panel to determine the appropriateness of admission and length of stay (LoS). Management alternatives were discussed.</p> <p>Results</p> <p>A total of 119 participants were recruited. 32 admissions were inappropriate and 83 were for an inappropriate duration. Whether a participant lived in their own home was predictive of an inappropriate admission. The number of LTNCs, number of presenting complaints and whether the participant lived alone in their own home were predictive of an inappropriate LoS. For admissions judged to be inappropriate, the panel suggested management alternatives.</p> <p>Conclusion</p> <p>Patients with LTNCs are being admitted to hospital when other services, e.g. ambulatory care, are available which could meet their needs. Inefficiencies in hospital procedures, such as discharge planning and patient transfers, continue to exist. Recognition of the need to plan for discharge at admission and to ensure in-patient services are provided in a timely manner may contribute towards improved efficiency.</p
In the absence of cancer registry data, is it sensible to assess incidence using hospital separation records?
BACKGROUND: Within the health literature, a major goal is to understand distribution of service utilisation by social location. Given equivalent access, differential incidence leads to an expectation of differential service utilisation. Cancer incidence is differentially distributed with respect to socioeconomic status. However, not all jurisdictions have incidence registries, and not all registries allow linkage with utilisation records. The British Columbia Linked Health Data resource allows such linkage. Consequently, we examine whether, in the absence of registry data, first hospitalisation can act as a proxy measure for incidence, and therefore as a measure of need for service. METHODS: Data are drawn from the British Columbia Linked Health Data resource, and represent 100% of Vancouver Island Health Authority cancer registry and hospital records, 1990–1999. Hospital separations (discharges) with principal diagnosis ICD-9 codes 140–208 are included, as are registry records with ICDO-2 codes C00-C97. Non-melanoma skin cancer (173/C44) is excluded. Lung, colorectal, female breast, and prostate cancers are examined separately. We compare registry and hospital annual counts and age-sex distributions, and whether the same individuals are represented in both datasets. Sensitivity, specificity and predictive values are calculated, as is the kappa statistic for agreement. The registry is designated the gold standard. RESULTS: For all cancers combined, first hospitalisation counts consistently overestimate registry incidence counts. From 1995–1999, there is no significant difference between registry and hospital counts for lung and colorectal cancer (p = 0.42 and p = 0.56, respectively). Age-sex distribution does not differ for colorectal cancer. Ten-year period sensitivity ranges from 73.0% for prostate cancer to 84.2% for colorectal cancer; ten-year positive predictive values range from 89.5% for female breast cancer to 79.35% for prostate cancer. Kappa values are consistently high. CONCLUSION: Claims and registry databases overlap with an appreciable proportion of the same individuals. First hospital separation may be considered a proxy for incidence with reference to colorectal cancer since 1995. However, to examine equity across cancer health services utilisation, it is optimal to have access to both hospital and registry files
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