Chaotic breccia zones on the Pembroke Peninsula, south Wales: Evidence for collapse into voids along dilational faults

Chaotic breccias and megabreccias – locally called gash breccias – hosted within the Pembroke Limestone Group (Visean, Mississippian, lower Carboniferous) of southwest Wales are re-mapped along with spatially-related crackle and mosaic breccias. Of thirteen studied megabreccia bodies, seven lie along steep, NNW- or NNE-striking strike-slip faults originating during north-south Variscan (late Carboniferous) shortening, though reactivated during later extension. Four bodies are conformable with E-W striking, steeply-dipping bedding, and two have irregular or indeterminate margins. The bedding-parallel zones are interpreted as the dilational tips of listric normal faults, and the cross-strike faults as transtensional transfer zones. Sub-horizontal clast fabrics suggest brecciation by gravitational collapse into opening fissures rather than by cataclasis along the faults. Most fissures have geometrically matched margins produced by this dilational faulting, and only locally have the indented margins indicating solutional processes. The most likely age for the main fissure extension and fill is late Triassic, based on analogous dated fills at the eastern end of the Bristol Channel Basin. The Pembroke megabreccias blur the distinction between fault rocks formed by deformation and those formed by redeposition along fault zones.This is the accepted manuscript version. The final version is available from Elsevier at http://www.sciencedirect.com/science/article/pii/S0191814114002338

ERK1/2, PI3K and p70S6K are important mediators for HGF-induced migration and invasion in human ovarian cancer cells

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Computational study of human head response to primary blast waves of five levels from three directions

Human exposure to blast waves without any fragment impacts can still result in primary blast-induced traumatic brain injury (bTBI). To investigate the mechanical response of human brain to primary blast waves and to identify the injury mechanisms of bTBI, a three-dimensional finite element head model consisting of the scalp, skull, cerebrospinal fluid, nasal cavity, and brain was developed from the imaging data set of a human female. The finite element head model was partially validated and was subjected to the blast waves of five blast intensities from the anterior, right lateral, and posterior directions at a stand-off distance of one meter from the detonation center. Simulation results show that the blast wave directly transmits into the head and causes a pressure wave propagating through the brain tissue. Intracranial pressure (ICP) is predicted to have the highest magnitude from a posterior blast wave in comparison with a blast wave from any of the other two directions with same blast intensity. The brain model predicts higher positive pressure at the site proximal to blast wave than that at the distal site. The intracranial pressure wave invariably travels into the posterior fossa and vertebral column, causing high pressures in these regions. The severities of cerebral contusions at different cerebral locations are estimated using an ICP based injury criterion. Von Mises stress prevails in the cortex with a much higher magnitude than in the internal parenchyma. According to an axonal injury criterion based on von Mises stress, axonal injury is not predicted to be a cause of primary brain injury from blasts. Copyright

Satellite estimates of wide-range suspended sediment concentrations in Changjiang (Yangtze) estuary using MERIS data

The Changjiang (Yangtze) estuarine and coastal waters are characterized by suspended sediments over a wide range of concentrations from 20 to 2,500 mg l-1. Suspended sediment plays important roles in the estuarine and coastal system and environment. Previous algorithms for satellite estimates of suspended sediment concentration (SSC) showed a great limitation in that only low to moderate concentrations (up to 50 mg l-1) could be reliably estimated. In this study, we developed a semi-empirical radiative transfer (SERT) model with physically based empirical coefficients to estimate SSC from MERIS data over turbid waters with a much wider range of SSC. The model was based on the Kubelka–Munk two-stream approximation of radiative transfer theory and calibrated using datasets from in situ measurements and outdoor controlled tank experiments. The results show that the sensitivity and saturation level of remote-sensing reflectance to SSC are dependent on wavelengths and SSC levels. Therefore, the SERT model, coupled with a multi-conditional algorithm scheme adapted to satellite retrieval of wide-range SSC, was proposed. Results suggest that this method is more effective and accurate in the estimation of SSC over turbid water

Using item response theory to explore the psychometric properties of extended matching questions examination in undergraduate medical education

BACKGROUND: As assessment has been shown to direct learning, it is critical that the examinations developed to test clinical competence in medical undergraduates are valid and reliable. The use of extended matching questions (EMQ) has been advocated to overcome some of the criticisms of using multiple-choice questions to test factual and applied knowledge. METHODS: We analysed the results from the Extended Matching Questions Examination taken by 4th year undergraduate medical students in the academic year 2001 to 2002. Rasch analysis was used to examine whether the set of questions used in the examination mapped on to a unidimensional scale, the degree of difficulty of questions within and between the various medical and surgical specialties and the pattern of responses within individual questions to assess the impact of the distractor options. RESULTS: Analysis of a subset of items and of the full examination demonstrated internal construct validity and the absence of bias on the majority of questions. Three main patterns of response selection were identified. CONCLUSION: Modern psychometric methods based upon the work of Rasch provide a useful approach to the calibration and analysis of EMQ undergraduate medical assessments. The approach allows for a formal test of the unidimensionality of the questions and thus the validity of the summed score. Given the metric calibration which follows fit to the model, it also allows for the establishment of items banks to facilitate continuity and equity in exam standards

Therapy: Metformin takes a new route to clinical efficacy.

International audienceMetformin is currently the first-line treatment option for patients with type 2 diabetes mellitus, yet its mechanism of action remains uncertain. A new study reveals the important role for the activation of a duodenal AMPK-dependent neuronal pathway in the acute antihyperglycaemic effect of metformin and the inhibition of hepatic glucose production

Six topics on inscribable polytopes

Inscribability of polytopes is a classic subject but also a lively research area nowadays. We illustrate this with a selection of well-known results and recent developments on six particular topics related to inscribable polytopes. Along the way we collect a list of (new and old) open questions.Comment: 11 page

Correlated fragile site expression allows the identification of candidate fragile genes involved in immunity and associated with carcinogenesis

Common fragile sites (cfs) are specific regions in the human genome that are particularly prone to genomic instability under conditions of replicative stress. Several investigations support the view that common fragile sites play a role in carcinogenesis. We discuss a genome-wide approach based on graph theory and Gene Ontology vocabulary for the functional characterization of common fragile sites and for the identification of genes that contribute to tumour cell biology. CFS were assembled in a network based on a simple measure of correlation among common fragile site patterns of expression. By applying robust measurements to capture in quantitative terms the non triviality of the network, we identified several topological features clearly indicating departure from the Erdos-Renyi random graph model. The most important outcome was the presence of an unexpected large connected component far below the percolation threshold. Most of the best characterized common fragile sites belonged to this connected component. By filtering this connected component with Gene Ontology, statistically significant shared functional features were detected. Common fragile sites were found to be enriched for genes associated to the immune response and to mechanisms involved in tumour progression such as extracellular space remodeling and angiogenesis. Our results support the hypothesis that fragile sites serve a function; we propose that fragility is linked to a coordinated regulation of fragile genes expression.Comment: 18 pages, accepted for publication in BMC Bioinformatic

Efficacy of N-acetyl cysteine in traumatic brain injury

In this study, using two different injury models in two different species, we found that early post-injury treatment with NAcetyl Cysteine (NAC) reversed the behavioral deficits associated with the TBI. These data suggest generalization of a protocol similar to our recent clinical trial with NAC in blast-induced mTBI in a battlefield setting [1], to mild concussion from blunt trauma. This study used both weight drop in mice and fluid percussion injury in rats. These were chosen to simulate either mild or moderate traumatic brain injury (TBI). For mice, we used novel object recognition and the Y maze. For rats, we used the Morris water maze. NAC was administered beginning 30-60 minutes after injury. Behavioral deficits due to injury in both species were significantly reversed by NAC treatment. We thus conclude NAC produces significant behavioral recovery after injury. Future preclinical studies are needed to define the mechanism of action, perhaps leading to more effective therapies in man

Current perceptions of the term Clinical Pharmacy and its relationship to Pharmaceutical Care:a survey of members of the European Society of Clinical Pharmacy

Background The definitions that are being used for the terms 'clinical pharmacy' and 'pharmaceutical care' seem to have a certain overlap. Responsibility for therapy outcomes seems to be especially linked to the latter term. Both terms need clarification before a proper definition of clinical pharmacy can be drafted. Objective To identify current disagreements regarding the term 'Clinical Pharmacy' and its relationship to 'Pharmaceutical Care' and to assess to which extent pharmacists with an interest in Clinical Pharmacy are willing to accept responsibility for drug therapy outcomes. Setting The membership of the European Society of Clinical Pharmacy. Methods A total of 1,285 individuals affiliated with the European Society of Clinical Pharmacy were invited by email to participate in an online survey asking participants to state whether certain professional activities, providers, settings, aims and general descriptors constituted (a) 'Clinical Pharmacy only', (b) 'Pharmaceutical Care only', (c) 'both' or (d) 'neither'. Further questions examined pharmacists' willingness to accept ethical or legal responsibility for drug therapy outcomes, under current and ideal working conditions. Main outcome measures Level of agreement with a number of statements. Results There was disagreement (&lt;80% agreement among all participants) regarding 'Clinical Pharmacy' activities, whether non-pharmacists could provide 'Clinical Pharmacy' services, and whether such services could be provided in non-hospital settings. There was disagreement (&lt;80% agreement among those linking items to Clinical Pharmacy) as to whether Pharmaceutical care also encompassed certain professional activities, constituted a scientific discipline and targeted cost effectiveness. The proportions of participants willing to accept legal responsibility under current/ideal working conditions were: safety (32.7%/64.3%), effectiveness (17.9%/49.2%), patient-centeredness (17.1%/46.2%), cost-effectiveness (20.3%/44.0%). Conclusions The survey identified key disagreements around the term 'Clinical Pharmacy' and its relationship to 'Pharmaceutical Care', which future discussions around a harmonised definition of 'Clinical Pharmacy' should aim to resolve. Further research is required to understand barriers and facilitators to pharmacists accepting responsibility for drug therapy outcomes.</p