4.6 billion year old aragonite and its implications for understanding the geological record of Ca-carbonate

Owing to its diagenetic instability, aragonite is rare in the geological record and almost entirely absent from pre-carboniferous sedimentary rocks. The former presence of this mineral in older deposits has to be inferred from petrographic, chemical or isotopic proxies. Crystals of aragonite that formed around 4563 million years ago occur in carbonaceous chondrite meteorites, showing that under certain conditions, the orthorhombic polymorph of Ca-carbonate can survive essentially indefinitely. Together with other carbonate minerals, phyllosilicates and sulphides, this aragonite formed by low-temperature water-mediated alteration of anhydrous minerals and glass in the interior of the meteorite’s parent asteroid(s). The survival of aragonite for such a long time can be attributed to the loss of free water by its incorporation into phyllosilicates, and to the very low permeability of the fine-grained and organic-rich rock matrix that prevented the ingress of fresh solutions via intergranular flow. By analogy with these meteorites, terrestrial aragonite is likely to survive where it has been similarly isolated from liquid water, particularly in organic-rich mudrocks, and such deposits may provide important new evidence for deducing the original mineralogy of skeletal and non-skeletal carbonates in deep-time

Laxatives do not improve symptoms of opioid-induced constipation: results of a patient survey

Introduction: Laxatives are commonly used to treat opioid-induced constipation, the commonest and most bothersome complication of opioids. However, laxatives have a non-specific action and do not target underlying mechanisms of opioid-induced constipation; their use is associated with abdominal symptoms that negatively impact quality of life. Objective: To assess the effects of laxatives in patients taking opioids for chronic pain. Methods: 198 UK patients who had taken opioid analgesics for at least one month completed a cross-sectional online or telephone survey. Questions addressed their pain condition and medication, and laxative use (including efficacy and side-effects). The survey also assessed bowel function using the Bowel Function Index. Results: Since starting their current opioid, 134/184 patients (73%) had used laxatives at some point and 122 (91%) of these were currently taking them. The most common laxatives were osmotics and stimulants. Laxative side-effects were reported in 75%, most commonly gas, bloating/fullness and a sudden urge to defecate. Side-effects were more common in patients <40 years old. Approximately half of patients said laxatives interfered with work and social activities, and one-fifth had needed an overnight hospital stay because of their pain condition and/or constipation. Laxatives did not improve the symptoms of constipation, as assessed by the Bowel Function Index. Constipation was not related to opioid strength or dose of opioid or number of laxatives taken. Conclusions: Use of laxatives to treat opioid-induced constipation is often ineffective and associated with side-effects. Instead of relieving the burden of opioid-induced constipation, laxative use is associated with a negative impact

The B -> Xs gamma Rate and CP Asymmetry within the Aligned Two-Higgs-Doublet Model

In the two-Higgs-doublet model the alignment of the Yukawa matrices in flavour space guarantees the absence of flavour-changing neutral currents at tree level, while introducing new sources for CP violation parametrized in a very economical way. This implies potentially large influence in a number of processes, b -> s gamma being a prominent example where rather high experimental and theoretical precision meet. We analyze the CP rate asymmetry in this inclusive decay and determine the resulting constraints on the model parameters. We demonstrate the compatibility with previously obtained limits. Moreover we extend the phenomenological analysis of the branching ratio, and examine the influence of resulting correlations on the like-sign dimuon charge asymmetry in B decays.Comment: 12 pages, 6 figures. Submitted to Phys.Rev.

The effect of carbohydrate ingestion on the Interleukin-6 response to a 90-minute run time trial

Fatigue is a predictable outcome of prolonged physical activity; yet its biological cause remains uncertain. During exercise, a polypeptide messenger molecule interleukin- 6 (IL-6) is actively produced. Previously, it has been demonstrated that administration of recombinant IL-6 (rhIL-6) impairs 10-km run performance and heightened sensation of fatigue in trained runners. Both high carbohydrate diets and carbohydrate ingestion during prolonged exercise have a blunting effect on IL-6 levels postendurance exercise. We hypothesized that carbohydrate ingestion may improve performance during a prolonged bout of exercise as a consequence of a blunted IL-6 response. Seven recreationally trained fasted runners completed two 90-min time trials under CHO supplemented and placebo conditions in a randomized order. The study was of a double-blinded, placebo-controlled, cross-over study design. Distance covered in 90 min was significantly greater following exogenous carbohydrate ingestion compared with the placebo trial (19.13 ± 1.7 km and 18.29 ± 1.9 km, respectively, p = .0022). While postexercise IL-6 levels were significantly lower in the CHO trial compared with the placebo trial (5.3 ± 1.9 pg·mL?1and 6.6 ± 3.0 pg·mL?1, respectively; p = .0313), this difference was considered physiologically too small to mediate the improvement in time trial performance

Cubical ethnography: Another kind of fieldwork

Studying the contemporary clinic necessitates rethinking what it means to both enter and access ‘the field’. In these Field Notes, I reflect on the beginnings of fieldwork and the processes of crafting research protocols which can stand up to formal ethics reviews. Rather than treating the process as a barrier to ‘real’ ethnographic research, I suggest that the mundane institutional realities of inserting oneself into a bureaucratic atmosphere form a particular—but no less valid—kind of ethnographic experience. I call this experience ‘cubicle ethnography’, after how the structures of the office—keys, badges, desktop computers—reflected negotiations of access and my own legitimacy as a visiting ethnographer.  &nbsp

The nature of the martian interior

Detailed models of the martian interior must be developed so that the results of future missions to Mars may be interpreted. Ab initio computer simulations are used to investigate the properties of iron sulphides as candidate phases for the martian core. The first simulations of experimentally observed and hypothetical phases of stoichiometric FeS and Fe3S provide details of the properties of these phases at high pressures that have yet to be investigated experimentally. Simulations of liquid iron sulphides constitute the first self-contained theoretical study of these liquids, providing new information about their structural, dynamical and bulk physical properties as a function of pressure, temperature and composition. New models of the martian interior are developed that are geophysically sound, consistent with observations of Mars, incorporate new results from simulations of liquid iron sulphides, and generate temperature, density and seismic wave velocity profiles as a function of depth. Calculated thermal profiles constrain the core to be liquid. For a core compositions of Fe ~16 wt%S and Fe ~27 wt%S the core radius is constrained to ~1500 - 1600 km and ~1600 - 1800 km, respectively. Calculated densities and adiabatic bulk modulus are consistent with a mantle composed of olivines, pyroxenes and garnets, and exclude a perovskite layer at the base of the mantle. New seismic profiles indicate that the average primary seismic wave velocity in the core is only ~3 km s-1. Geology, magnetic, gravity, topography datasets for six regions of Mars are studied. There is no clear trend of correlations between the datasets across the studied regions. Resurfacing is not a cause of first order density and magnetic contrasts. Crustal remanent magnetic anomalies are more likely to be associated with underlying bedrock than with erosional and depositional processes or products. Current understanding of these anomalies is not sufficient to further constrain models of the martian interior

Palinología e importancia paleoambiental de la Formación Tunal (Daniano) en su localidad tipo, Quebrada el Chorro (Salta, Argentina).

The palynologic investigation of samples from the Tunal Formation at El Chorro creek (Salta, Argentina) resulted in the recovery of terrestrial assemblages of pollen and spores associated with freshwater algae (Pediastrum spp. and Scenedesmus sp.). Of the 43 species of sporomorphs identified for the Tunal Formation so far, 28 species are cited here for the first time. The spores and pollen indicate a Danian age at the type locality. Sedimentary proxidata including abundant evaporites suggest intervals of at least seasonal arid environmental conditions. In contrast, the palynologic assemblages recovered from the organic rich dark shales indicate the presence of swampy areas and forests surrounding them. The dominance of Verrustephanoporites simplex Leidelmeyer (corresponding to the modern Phyllostylon, Ulmaceae) indicates abundant seasonal rainfalls, warm humid conditions and subtropical climate.La investigación palinológica de muestras extraídas de la Formación Tunal en la quebrada El Chorro (Salta, Argentina) resultó en la recuperación de una asociación de polen y esporas, juntamente con algas de agua dulce (Pediastrum spp. y Scenedesmus sp.). De las 43 especies de esporomorfos identificadas hasta el momento para la Formación Tunal, 28 se citan aquí por primera vez. Las esporas y polen indican edad Daniana en la localidad tipo. Los proxidata sedimentarios incluyendo abundantes evaporitas, sugieren intervalos al menos estacionales de condiciones ambientales áridas. Por otro lado, las asociaciones palinológicas recuperadas de las pelitas oscuras ricas en materia orgánica indican la presencia de áreas anegadas y selvas en sus alrededores. En las últimas, el predominio de Verrustephanoporites simplex Leidelmeyer (que se corresponde con el actual Phyllostylon, Ulmaceae) indica abundantes lluvias estacionales, condiciones cálido-húmedas y clima subtropicalFil: Volkheimer, Wolfang. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Novara, Martin Guillermo. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Narvaez, Paula Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Marquillas, Rosa Argentina. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentin