Close Cassini flybys of Saturn's ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus.

Saturn's main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. Data on the moons' morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. We find that the optical properties of the moons' surfaces are determined by two competing processes: contamination by a red material formed in Saturn's main ring system and accretion of bright icy particles or water vapor from volcanic plumes originating on the moon Enceladus.

Radiological progression of end colostomy trephine diameter and area.

Background: Development of a parastomal hernia is common following abdominoperineal excision (APE). The true incidence is difficult to assess fully owing to differing lengths of follow-up and techniques used to assess herniation; radiological or clinical. The primary aim of this study was to evaluate colostomy diameter by studying the rate of change of axial and sagittal trephine diameters, trephine area, and the ratio of the trephine over time. A secondary aim was to investigate variation in trephine area and variables affecting parasternal hernia over time. Methods: Serial CT scans performed after APE from January 2006 to December 2014 were reviewed. Variables analysed included age, sex, trephine position relative to rectus abdominis muscle (RAM), type of incision for stoma creation, and axial and sagittal trephine diameters measured on follow-up CT. A Bayesian hierarchical modelling framework was used to examine the relationship of trephine diameters, area and ratio over time. Results: Of 112 patients undergoing APE, 103 were eligible for analysis; this included 91 colostomies (88·3 per cent) through the RAM and 12 (11·7 per cent) lateral to the RAM. Median age of the patients was 68 years. Sixty patients (58·3 per cent) had a circular and 43 (41·7 per cent) a cruciate incision for stoma creation. The sagittal trephine diameter increased by 0·22 (95 per cent credible interval 0·12 to 0·32) mm/month for both sexes. Women reported a significant increase in axial trephine diameters; the male : female ratio difference was -0·17 (-0·30 to -0·03) mm/month and for trephine areas -6·21 (0·96 to 13·7) mm2/month. Patient age, colostomy trephine location and shape of incision were not statistically significant variables for parasternal hernia. Conclusion: Female sex was the only variable affecting the rate of increase in axial trephine diameter and trephine area over time.

Exposure to an anti-androgenic herbicide negatively impacts reproductive physiology and fertility in Xenopus tropicalis.

Amphibians are threatened on a global scale and pollutants may be contributing to population declines, but how chemicals impact on their reproduction is poorly understood. We conducted a life cycle analysis to investigate the impacts of early life exposure to two anti-androgens (exposure until completion of metamorphosis;stage 66): flutamide, (50 µg/L)/linuron (9 and 45 µg/L)) on sexual development and breeding competence in Xenopus tropicalis. Our analyses included: mRNA levels of dmrt1, cyp17, amh, cyp19, foxl2 and ar (tadpoles/metamorphs), gonadal histomorphology (metamorphs/adults), mRNA levels of ar/gr (adult male brain/gonad/forelimb), testosterone/corticosterone levels (adult males), secondary sexual characteristics (forelimb width/nuptial pad: adult males) and breeding competence (amplexus/fertility: adult males). Compared to controls, feminised sex ratios and increased number of spermatogonia (adults) were observed after exposure to flutamide and the lower linuron concentration. Exposure to the lower linuron concentration also resulted in demasculinisation of secondary sexual characteristics and reduced male fertility. Flutamide exposure resulted in masculinisation of the nuptial pad and elevated mRNA levels of dmrt1, cyp17, amh and foxl2 in brains (metamorphs). Testosterone levels were higher in all treatment groups, however, overall few effects were observed in response to the higher linuron concentration. Our findings advance understanding of reproductive biology of X. tropicalis and illustrate negative effects of linuron on reproductive processes at a concentration measured in freshwater environments.

On the use of Bayesian decision theory for issuing natural hazard warnings.

Warnings for natural hazards improve societal resilience and are a good example of decision-making under uncertainty. A warning system is only useful if well defined and thus understood by stakeholders. However, most operational warning systems are heuristic: not formally or transparently defined. Bayesian decision theory provides a framework for issuing warnings under uncertainty but has not been fully exploited. Here, a decision theoretic framework is proposed for hazard warnings. The framework allows any number of warning levels and future states of nature, and a mathematical model for constructing the necessary loss functions for both generic and specific end-users is described. The approach is illustrated using one-day ahead warnings of daily severe precipitation over the UK, and compared to the current decision tool used by the UK Met Office. A probability model is proposed to predict precipitation, given ensemble forecast information, and loss functions are constructed for two generic stakeholders: an end-user and a forecaster. Results show that the Met Office tool issues fewer high-level warnings compared with our system for the generic end-user, suggesting the former may not be suitable for risk averse end-users. In addition, raw ensemble forecasts are shown to be unreliable and result in higher losses from warnings.

The interactions between municipal socioeconomic status and age on hip fracture risk.

SUMMARY: Age modifies the effect of area-level socioeconomic status (SES) in the risk of fragility hip fractures (HF). For older individuals, the risk of HF increases as SES increases. For younger individuals, risk of HF increases as SES decreases. Our study may help decision-makers to better direct the implementation of political decisions. INTRODUCTION: The effect of socioeconomic status (SES) on hip fracture (HF) incidence remains unclear. The objective of this study is to evaluate the association between HF incidence and municipality-level SES as well as interactions between age and SES. METHODS: From the Portuguese Hospital Discharge Database, we selected hospitalizations (2000-2010) of patients aged 50+, with HF diagnosis (codes 820.x, ICD9-CM), caused by traumas of low/moderate energy, excluding bone cancer cases and readmissions for aftercare. Municipalities were classified according to SES (deprived to affluent) using 2001 Census data. A spatial Bayesian hierarchical regression model (controlling for data heterogeneity and spatial autocorrelation), using the Poisson distribution, was used to quantify the relative risk (RR) of HF, 95% credible interval (95%CrI), and analyze the interaction between age and SES after adjusting for rural conditions. RESULTS: There were 96,905 HF, 77.3% of which were on women who, on average, were older than men (mean age 81.2±8.5 vs 78.2±10.1 years) at admission (p<0.001). In women, there was a lower risk associated with better SES: RR=0.83 (95%CrI 0.65-1.00) for affluent versus deprived. There was an inverse association between SES and HF incidence rate in the youngest and a direct association in the oldest, for both sexes, but significant only between deprived and affluent in older ages (≥75 years). CONCLUSIONS: Interaction between SES and age may be due to inequalities in lifestyles, access to health systems, and preventive actions. These results may help decision-makers to better understand the epidemiology of hip fractures and to better direct the available funding.

The Opportunity Rover's Athena science investigation at Meridiani Planum, Mars.

The Mars Exploration Rover Opportunity has investigated the landing site in Eagle crater and the nearby plains within Meridiani Planum. The soils consist of fine-grained basaltic sand and a surface lag of hematite-rich spherules, spherule fragments, and other granules. Wind ripples are common. Underlying the thin soil layer, and exposed within small impact craters and troughs, are flat-lying sedimentary rocks. These rocks are finely laminated, are rich in sulfur, and contain abundant sulfate salts. Small-scale cross-lamination in some locations provides evidence for deposition in flowing liquid water. We interpret the rocks to be a mixture of chemical and siliciclastic sediments formed by episodic inundation by shallow surface water, followed by evaporation, exposure, and desiccation. Hematite-rich spherules are embedded in the rock and eroding from them. We interpret these spherules to be concretions formed by postdepositional diagenesis, again involving liquid water.

Soils of Eagle crater and Meridiani Planum at the Opportunity Rover landing site.

The soils at the Opportunity site are fine-grained basaltic sands mixed with dust and sulfate-rich outcrop debris. Hematite is concentrated in spherules eroded from the strata. Ongoing saltation exhumes the spherules and their fragments, concentrating them at the surface. Spherules emerge from soils coated, perhaps from subsurface cementation, by salts. Two types of vesicular clasts may represent basaltic sand sources. Eolian ripples, armored by well-sorted hematite-rich grains, pervade Meridiani Planum. The thickness of the soil on the plain is estimated to be about a meter. The flatness and thin cover suggest that the plain may represent the original sedimentary surface.

Chemistry of rocks and soils at Meridiani Planum from the Alpha Particle X-ray Spectrometer.

The Alpha Particle X-ray Spectrometer on the Opportunity rover determined major and minor elements of soils and rocks in Meridiani Planum. Chemical compositions differentiate between basaltic rocks, evaporite-rich rocks, basaltic soils, and hematite-rich soils. Although soils are compositionally similar to those at previous landing sites, differences in iron and some minor element concentrations signify the addition of local components. Rocky outcrops are rich in sulfur and variably enriched in bromine relative to chlorine. The interaction with water in the past is indicated by the chemical features in rocks and soils at this site.

The Spirit Rover's Athena science investigation at Gusev Crater, Mars.

The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.

Chemistry of rocks and soils in Gusev Crater from the alpha particle x-ray spectrometer.

The alpha particle x-ray spectrometer on the Spirit rover determined major and minor elements of soils and rocks in Gusev crater in order to unravel the crustal evolution of planet Mars. The composition of soils is similar to those at previous landing sites, as a result of global mixing and distribution by dust storms. Rocks (fresh surfaces exposed by the rock abrasion tool) resemble volcanic rocks of primitive basaltic composition with low intrinsic potassium contents. High abundance of bromine (up to 170 parts per million) in rocks may indicate the alteration of surfaces formed during a past period of aqueous activity in Gusev crater.

Curium-244 alpha-sources for space research

Special alpha-proton-X-ray spectrometric complexes (APXS) have been developed in order to perform chemical analyses of the Mars atmosphere and rock surface compounds by alpha back-scattering, alpha-proton measurements, and X-ray fluorescence. The sources were prepared by high temperature condensation of metal curium vapour onto silicon substrates. They are silicon disks with curium-244 fixed on their surfaces as a silicide. The sources have overall dimensions as follows: disk diameter 8 mm; thickness 0.3 mm; and 6 mm diameter active spot. The source activities are 5 +/- 1 mCi and the alpha-line half-widths are equal to (1.7-2.5) and (2.9-4.5)% of full width at 10% of Maximum (Maximum is equal to 5.8 MeV). Thermovacuum (from 196 to 1000 degrees C), mechanical, and resource tests were performed and demonstrated that the sources maintained their characteristics. The applicability of the sources for the above-mentioned analytical purposes was confirmed during NASA Mars Pathfinder mission.

Overview of the Mars Pathfinder mission and assessment of landing site predictions.

Chemical analyses returned by Mars Pathfinder indicate that some rocks may be high in silica, implying differentiated parent materials. Rounded pebbles and cobbles and a possible conglomerate suggest fluvial processes that imply liquid water in equilibrium with the atmosphere and thus a warmer and wetter past. The moment of inertia indicates a central metallic core of 1300 to 2000 kilometers in radius. Composite airborne dust particles appear magnetized by freeze-dried maghemite stain or cement that may have been leached from crustal materials by an active hydrologic cycle. Remote-sensing data at a scale of generally greater than approximately 1 kilometer and an Earth analog correctly predicted a rocky plain safe for landing and roving with a variety of rocks deposited by catastrophic floods that are relatively dust-free.

The chemical composition of Martian soil and rocks returned by the mobile alpha proton X-ray spectrometer: preliminary results from the X-ray mode.

The alpha proton x-ray spectrometer (APXS) on board the rover of the Mars Pathfinder mission measured the chemical composition of six soils and five rocks at the Ares Vallis landing site. The soil analyses show similarity to those determined by the Viking missions. The analyzed rocks were partially covered by dust but otherwise compositionally similar to each other. They are unexpectedly high in silica and potassium, but low in magnesium compared to martian soils and martian meteorites. The analyzed rocks are similar in composition to terrestrial andesites and close to the mean composition of Earth's crust. Addition of a mafic component and reaction products of volcanic gases to the local rock material is necessary to explain the soil composition.

Reversal of small intestinal bypass operations and concomitant vertical banded gastroplasty: long-term outcome.

BACKGROUND: Long-term complications of jejunoileal bypass (JIB) have been reported, prompting restoration of intestinal continuity and concomitant performance of vertical banded gastroplasty (VBG) for weight control. The aim of this study was to evaluate the presentation and reversal of JIB complications, late complications, mortality, and long-term weight control in patients who have undergone JIB reversal and concomitant VBG. STUDY DESIGN: From 1981 to 1994, 37 patients were treated for complications from JIB that included diarrhea (73 percent), arthritis (46 percent), malnutrition (22 percent), urolithiasis (19 percent), electrolyte disorders (19 percent), and lack of weight loss (8 percent). Four patients required preoperative parenteral nutrition to correct protein and electrolyte imbalances. Surgical management of all 37 patients included restoration of bowel continuity and VBG during the same operative procedure. RESULTS: Postoperative complications occurred in 11 patients, including prolonged ileus in seven patients, pancreatitis in three patients, and infectious complications in two. There were no deaths. Late morbidity included staple line dehiscence in four patients, incisional hernia in three patients, and reversal of the VBG in one. All patients with diarrhea, malnutrition, electrolyte disorders, and lack of weight loss had resolution of their symptoms, while urolithiasis and arthritis resolved in 86 and 53 percent of patients, respectively. In patients available for five-year follow-up evaluation, weight changes were small, shifting from a preoperative weight of 87 +/- 19 to 90 +/- 19 kg at five years (mean +/- SD). CONCLUSIONS: Restoration of intestinal continuity combined with VBG is a safe and effective operation that will reverse most of the long-term complications of JIB and provide stable weight control for up to five years.

An experimental study to determine the effects of Dermagraft on skin graft viability in the presence of bacterial wound contamination.

Dermagrafts (Advanced Tissue Science, La Jolla, Calif.) is a possible dermal substitute currently in early stages of clinical trials. It consists of polyglycolic acid mesh impregnated with viable, human, neonatal fibroblasts. The randomized prospective study with the mouse model was undertaken to determine the effect of Dermagraft on skin graft viability in the presence of wound contamination with controlled concentrations of commonly encountered burn wound pathogens. Appropriate controlled series were run concurrently. Placement of Dermagraft, or polyglycolic acid mesh, had no significant effect on skin graft viability when compared with simple skin grafts. Controlled bacterial contamination of skin grafts with Dermagraft did not significantly change the occurrence of graft viability when compared with control groups of skin grafts with controlled bacterial contamination. These studies suggest that Dermagraft does not increase the occurrence of graft loss in the face of wound bed contamination.

Immunohistochemical localization of fibronectin in the chinchilla cochlea.

The purpose of this study was to better understand the molecular composition of the cochlea. Fibronectin (FN), a well characterized adhesive glycoprotein, was localized by immunofluorescence microscopy in fresh and fixed cochlear tissues, and in fixed kidney tissue, using a polyclonal, affinity-purified, rabbit, anti-fibronectin antibody and a secondary antibody coupled to FITC. The FN antibody was free from cross-reactivity with other known basement membrane and cell matrix molecules. FN reactivity in the cochlea was most intense in the basilar membrane, latero-basal borders of Boettcher's cells, otic capsule, endothelial basement membranes (particularly those of the stria vascularis), and as a diffuse, fan-shaped network radiating into the spiral ligament. Little FN labelling was present in the epithelial basement membranes. Negative control tissue showed no immunoreactivity; whereas, positive kidney control tissue showed appropriate FN immunoreactivity in the mesangium of the glomerulus. The most significant finding of this study was that FN is a major component of the basilar membrane and its distribution appears to correspond to the amorphous ground substance. FN was not localized in the organ of Corti or at the tips of the hair-cell stereocilia.

Juvenile nasopharyngeal angiofibroma: an update of the UCLA experience, 1960-1985.

The UCLA experience with juvenile angiofibroma (JNA) over a 25-year period is reviewed. There were 83 patients, the majority being adolescent males. Surgery was the primary method of treatment for disease not extending intracranially; 63 of 68 patients (92.5%) became asymptomatic with this modality. In patients treated with a single course of primary radiation, 10 of 14 (78.5%) became asymptomatic. Trends in diagnosis and treatment were evaluated. Contrast computerized tomography reliably assesses tumor extent. Preoperative arteriography is essential for the evaluation and embolization of feeding vessels; this in turn significantly reduces operative blood loss and the need for transfusions. Radiotherapy should be reserved for disease extending intracranially and should be in doses of 3,600 cGy or larger.

Heavy elements in surface materials: determination by alpha particle scattering.

The backscattering of alpha particles from a radioactive source can be used to determine the amounts of heavy elements such as lead in surface materials. A light, portable instrument has been constructed that can be used as a survey meter for painted surfaces. It has a sensitivity of 0.3 percent by weight in a measurement of a few minutes.