129 research outputs found

    The Compositions of Kuiper Belt Objects

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    Objects in the Kuiper belt are small and far away thus difficult to study in detail even with the best telescopes available at earth. For much of the early history of the Kuiper belt, studies of the compositions of these objects were relegated to collections of moderate quality spectral and photometric data that remained difficult to interpret. Much early effort was put into simple correlations of surface colors and identifications of spectral features, but it was difficult to connect the observations to a larger understanding of the region. The last decade, however, has seen a blossoming in our understanding of the compositions of objects in the Kuiper belt. This blossoming is a product of the discoveries of larger -- and thus easier to study -- objects, continued dedication to the collection of a now quite large collection of high quality photometric and spectroscopic observations, and continued work at the laboratory and theoretical level. Today we now know of many processes which affect the surface compositions of objects in the Kuiper belt, including atmospheric loss, differentiation and cryovolcanism, radiation processing, the effects of giant impacts, and the early dynamical excitation of the Kuiper belt. We review the large quantity of data now available and attempt to build a comprehensive framework for understanding the surface compositions and their causes. In contrast to surface compositions, the bulk compositions of objects in the Kuiper belt remain poorly measured and even more poorly understood, but prospects for a deeper understanding of the formation of the the outer solar are even greater from this subject.Comment: 38 pages, 10 figures, to appear in Annual Reviews of Earth and Planetary Science

    Delivery of Complex Organic Compounds from Evolved Stars to the Solar System

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    Stars in the late stages of evolution are able to synthesize complex organic compounds with aromatic and aliphatic structures over very short time scales. These compounds are ejected into the interstellar medium and distributed throughout the Galaxy. The structures of these compounds are similar to the insoluble organic matter found in meteorites. In this paper, we discuss to what extent stellar organics has enriched the primordial Solar System and possibly the early Earth

    Correcting non cephalic presentation with moxibustion: study protocol for a multi-centre randomised controlled trial in general practice

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    <p>Abstract</p> <p>Background</p> <p>Non cephalic presentation in childbirth involves various risks to both the mother and the foetus. The incidence in Spain is 3.8% of all full-term pregnancies. The most common technique used to end the gestation in cases of non cephalic presentation is that of caesarian section, and although it provokes a lower rate of morbi-mortality than does vaginal delivery in such situations, there remains the possibility of traumatic injury to the foetal head and neck, while maternal morbidity is also increased. The application of heat (moxibustion) to an acupuncture point, in order to correct non cephalic presentation, has been practised in China since ancient times, but as yet there is insufficient evidence of its real effectiveness.</p> <p>Methods/Design</p> <p>The experimental design consists of a multi-centre randomised controlled trial with three parallel arms, used to compare real moxibustion, sham moxibustion and the natural course of events, among pregnant women with a non cephalic presentation and a gestational duration of 33–35 weeks (estimated by echography). The participants in the trial will be blinded to both interventions. The results obtained will be analyzed by professionals, blinded with respect to the allocation to the different types of intervention. In addition, we intend to carry out a economic analysis.</p> <p>Discussion</p> <p>This trial will contribute to the development of evidence concerning moxibustion in the correction of non cephalic presentations. The primary outcome variable is the proportion of cephalic presentations at term. As secondary outcomes, we will evaluate the proportion of cephalic presentations at week 38 of gestation, determined by echography, together with the safety of the technique, the specificity of moxibustion and the control of the blinding process.</p> <p>This study has been funded by the Health Ministry of the Andalusian Regional Government.</p> <p>Trial registration</p> <p>Current Controlled Trials ISRCTN10634508.</p

    Cord blood calcium, phosphate, magnesium, and alkaline phosphatase gestational age-specific reference intervals for preterm infants

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    <p>Abstract</p> <p>Background</p> <p>The objective was to determine the influence of gestational age, maternal, and neonatal variables on reference intervals for cord blood bone minerals (calcium, phosphate, magnesium) and related laboratory tests (alkaline phosphatase, and albumin-adjusted calcium), and to develop gestational age specific reference intervals based on infants without influential pathological conditions.</p> <p>Methods</p> <p>Cross-sectional study. 702 babies were identified as candidates for this study in a regional referral neonatal unit. After exclusions (for anomalies, asphyxia, maternal magnesium sulfate administration, and death), relationships were examined between cord blood serum laboratory analytes (calcium, phosphate, magnesium, alkaline phosphatase, and albumin-adjusted calcium) with gestation age and also with maternal and neonatal variables using multiple linear regression. Infants with influential pathological conditions were omitted from the development of gestational age specific reference intervals for the following categories: 23-27, 28-31, 32-34, 35-36 and > 36 weeks.</p> <p>Results</p> <p>Among the 506 preterm and 54 terms infants included in the sample. Phosphate, magnesium, and alkaline phosphatase in cord blood serum decreased with gestational age, calcium increased with gestational age. Those who were triplets, small for gestational age, and those whose mother had pregnancy-induced hypertension were influential for most of the analytes. The reference ranges for the preterm infants ≥ 36 weeks were: phosphate 1.5 to 2.6 mmol/L (4.5 to 8.0 mg/dL), calcium: 2.1 to 3.1 mmol/L (8.3 to 12.4 mg/dL); albumin-adjusted calcium: 2.3 to 3.2 mmol/L (9.1 to 12.9 mg/dL); magnesium 0.6 to 1.0 mmol/L (1.4 to 2.3 mg/dL), and alkaline phosphatase 60 to 301 units/L.</p> <p>Conclusions</p> <p>These data suggest that gestational age, as well as potentially pathogenic maternal and neonatal variables should be considered in the development of reference intervals for preterm infants.</p

    Saturn satellites as seen by Cassini Mission

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    In this paper we will summarize some of the most important results of the Cassini mission concerning the satellites of Saturn. Given the long duration of the mission, the complexity of the payload onboard the Cassini Orbiter and the amount of data gathered on the satellites of Saturn, it would be impossible to describe all the new discoveries made, therefore we will describe only some selected, paramount examples showing how Cassini's data confirmed and extended ground-based observations. In particular we will describe the achievements obtained for the satellites Phoebe, Enceladus and Titan. We will also put these examples in the perspective of the overall evolution of the system, stressing out why the selected satellites are representative of the overall evolution of the Saturn system.Comment: 34 pages, 10 figures, to appear on the special issue of Earth, Moon and Planets for the Elba worksho

    The Main Belt Comets and ice in the Solar System

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    We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies

    Trends in postpartum hemorrhage in high resource countries: a review and recommendations from the International Postpartum Hemorrhage Collaborative Group

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    <p>Abstract</p> <p>Background</p> <p>Postpartum hemorrhage (PPH) is a major cause of maternal mortality and morbidity worldwide. Several recent publications have noted an increasing trend in incidence over time. The international PPH collaboration was convened to explore the observed trends and to set out actions to address the factors identified.</p> <p>Methods</p> <p>We reviewed available data sources on the incidence of PPH over time in Australia, Belgium, Canada, France, the United Kingdom and the USA. Where information was available, the incidence of PPH was stratified by cause.</p> <p>Results</p> <p>We observed an increasing trend in PPH, using heterogeneous definitions, in Australia, Canada, the UK and the USA. The observed increase in PPH in Australia, Canada and the USA was limited solely to immediate/atonic PPH. We noted increasing rates of severe adverse outcomes due to hemorrhage in Australia, Canada, the UK and the USA.</p> <p>Conclusion</p> <p><it>Key Recommendations</it></p> <p indent="1">1. Future revisions of the International Classification of Diseases should include separate codes for atonic PPH and PPH immediately following childbirth that is due to other causes. Also, additional codes are required for placenta accreta/percreta/increta.</p> <p indent="1">2. Definitions of PPH should be unified; further research is required to investigate how definitions are applied in practice to the coding of data.</p> <p indent="1">3. Additional improvement in the collection of data concerning PPH is required, specifically including a measure of severity.</p> <p indent="1">4. Further research is required to determine whether an increased rate of reported PPH is also observed in other countries, and to further investigate potential risk factors including increased duration of labor, obesity and changes in second and third stage management practice.</p> <p indent="1">5. Training should be provided to all staff involved in maternity care concerning assessment of blood loss and the monitoring of women after childbirth. This is key to reducing the severity of PPH and preventing any adverse outcomes.</p> <p indent="1">6. Clinicians should be more vigilant given the possibility that the frequency and severity of PPH has in fact increased. This applies particularly to small hospitals with relatively few deliveries where management protocols may not be defined adequately and drugs or equipment may not be on hand to deal with unexpected severe PPH.</p

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