The weather report from IRC+10216: Evolving irregular clouds envelop carbon star

High angular resolution images of IRC+10216 are presented in several near-infrared wavelengths spanning more than 8 years. These maps have been reconstructed from interferometric observations obtained at both Keck and the VLT, and also from stellar occultations by the rings of Saturn observed with the Cassini spacecraft. The dynamic inner regions of the circumstellar environment are monitored over eight epochs ranging between 2000 January and 2008 July. The system is shown to experience substantial evolution within this period including the fading of many previously reported persistent features, some of which had been identified as the stellar photosphere. These changes are discussed in the context of existing models for the nature of the underlying star and the circumstellar environment. With access to these new images, we are able to report that none of the previously identified bright spots in fact contains the star, which is buried in its own dust and not directly visible in the near-infrared

Two-band second moment model and an interatomic potential for caesium

A semi-empirical formalism is presented for deriving interatomic potentials for materials such as caesium or cerium which exhibit volume collapse phase transitions. It is based on the Finnis-Sinclair second moment tight binding approach, but incorporates two independent bands on each atom. The potential is cast in a form suitable for large-scale molecular dynamics, the computational cost being the evaluation of short ranged pair potentials. Parameters for a model potential for caesium are derived and tested

An aggravated trajectory of depression and anxiety co-morbid with hepatitis C: : A 21 to 62 month follow-up study in 61 South Australian outpatients

BACKGROUND: This study aimed to explore the course of depression and anxiety in chronic hepatitis C patients. METHODS:   Data were combined from two studies: (1) Hospital Anxiety and Depression Scale (HADS) scores in 395 consecutive Australian outpatients from 2006 to 2010 formed the baseline measurement; and (2) Depression Anxiety Stress Scales (DASS) scores in a survey of a sub-sample of these patients in 2011 formed the follow-up measurement. After converting DASS to HADS scores, changes in symptom scores and rates of case-ness (≥8), and predictors of follow-up symptoms were assessed. RESULTS:   Follow-up data were available for 61 patients (70.5% male) whose age ranged from 24.5 to 74.6 years (M=45.6). The time to follow-up ranged from 20.7 to 61.9 months (M=43.8). Baseline rates of depression (32.8%) and anxiety (44.3%) increased to 62.3% and 67.2%, respectively. These findings were confirmed, independent of the conversion, by comparing baseline HADS and follow-up DASS scores with British community norms. Baseline anxiety and younger age predicted depression, while baseline anxiety, high school non-completion, and single relationship status predicted anxiety. CONCLUSION:  This study demonstrated a worsening trajectory of depression and anxiety. Further controlled and prospective research in a larger sample is required to confirm these findings

The rate of hypo-osmotic challenge influences regulatory volume decrease (RVD) and mechanical properties of articular chondrocytes

Zhao Wang is funded on a China Scholarships PhD Studentship. Jerome Irianto was supported on a project grant from The Wellcome Trust (ref no. 084717)

Pioneering a novel synthetic heart valve

Introduction Cardiac valve disease results in a disruption to haemodynamics, with frequent progression to end stage heart failure if left untreated. Valve replacement restores function to the heart and thus represents a lifesaving procedure [1]. Synthetic heart valves combine the durability of mechanical valves with the haemocompatibility of bioprosthetic valves. However, challenges including calcification, leaflet tearing and poor surface morphology mean that they have yet to reach clinical translation. The design of the Wheatley Heart Valve (WHV, Figure 1a) differs considerably from existing polymeric heart valves as it can be mathematically defined through a series of contiguous circles [2]. This permits changes to the design to be parametrically investigated (by changing the radius of the free edge and leaflet height) and facilitates a sinus washout through helical flow as blood exists the aorta. Computational mathematical modelling, in vitro testing and advanced surface characterisation technologies are investigated to advance the WHV closer towards clinical translation. Methods The leaflets were fabricated from solvent cast films of CarbothaneTM, an aliphatic polyurethane elastomer, which are then laser cut into leaflets. Sintered titanium stents were produced through additive manufacturing and the leaflets attached at the base and commissures via mechanical fixtures to form a tri-leaflet valve having both a concave and convex free edge. Flow performance through the valve was investigated through both steady (Ansys Fluent) and time-dependent (LS-Dyna) computational fluid modelling. Experimental tests were conducted through use of an in-house built pulse duplicator, based on a 3-element Windkessel model and a durability tester (ViVitro HiCycle). Pressure readings were taken using a Biopac MP36 System. Results & Discussion Our steady state computational analysis confirmed that that the unique curvature of the WHV facilitates helical blood flow downstream of the valve (Figure 1(b)). Work is ongoing to optimise the leaflet properties of the WHV by conducting an iterative process between our mathematical models and our in vitro bench tests. Investigations are also underway to enhancing the surface properties with Diamond Like Carbon (DLC) coatings using an ECR (electron cyclotron resonance) ion beam deposition facility. DLC are a class of amorphous carbons having similar properties to diamond, containing a mixture of both sp2 and sp3 carbon-carbon interatomic bonds. They have gained interest in medical applications due to their chemical inertness, and similar platelet absorption to LTI carbon (currently used as coatings in mechanical valves). Early investigations have demonstrated good adhesion of DLC films having a thickness of approximately 100 nm on our polymer leaflets. Further work will explore their biocompatibility and mechanical characteristics to enhance the performance of the WHV. Conclusion The WHV is a novel synthetic heart valve with the potential to facilitate a washout of blood flow as the leaflets close. Testing is ongoing in accordance with ISO 5840-1 and -2 to advance the WHV towards clinical translation

Failure of spot welds under in-plane static loading

Under in-plane loading conditions, two independent modes contribute to the failure of a spot weld: the in-plane shear mode and the in-plane rotational mode. In this work, the failures of both modes under large static load are examined individually. To study the combined failure of these two modes, two special test coupons are designed. The first coupon contains one spot weld. The second coupon contains five spot welds. Tests conducted in this work show that a very simple force-based failure criterion can be used to predict the failure of a spot weld under large in-plane combined static loads. Current multiaxial failure theory cannot explain this combined failure. This force-based spot weld failure criterion fits current automotive industry needs for body shell finite element application very well.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43935/1/11340_2006_Article_BF02323111.pd

Search for a strongly decaying neutral charmed pentaquark

We present a search for a charmed pentaquark decaying strongly to $D^{(*)-}p$. Finding no evidence for such a state, we set limits on the cross section times branching ratio relative to $D^{*-}$ and $D^-$ under particular assumptions about the production mechanism.Comment: To be published in Physics Letters

Human upper-airway respiratory airflow: In vivo comparison of computational fluid dynamics simulations and hyperpolarized 129Xe phase contrast MRI velocimetry

Computational fluid dynamics (CFD) simulations of respiratory airflow have the potential to change the clinical assessment of regional airway function in health and disease, in pulmonary medicine and otolaryngology. For example, in diseases where multiple sites of airway obstruction occur, such as obstructive sleep apnea (OSA), CFD simulations can identify which sites of obstruction contribute most to airway resistance and may therefore be candidate sites for airway surgery. The main barrier to clinical uptake of respiratory CFD to date has been the difficulty in validating CFD results against a clinical gold standard. Invasive instrumentation of the upper airway to measure respiratory airflow velocity or pressure can disrupt the airflow and alter the subject’s natural breathing patterns. Therefore, in this study, we instead propose phase contrast (PC) velocimetry magnetic resonance imaging (MRI) of inhaled hyperpolarized 129Xe gas as a non-invasive reference to which airflow velocities calculated via CFD can be compared. To that end, we performed subject-specific CFD simulations in airway models derived from 1H MRI, and using respiratory flowrate measurements acquired synchronously with MRI. Airflow velocity vectors calculated by CFD simulations were then qualitatively and quantitatively compared to velocity maps derived from PC velocimetry MRI of inhaled hyperpolarized 129Xe gas. The results show both techniques produce similar spatial distributions of high velocity regions in the anterior-posterior and foot-head directions, indicating good qualitative agreement. Statistically significant correlations and low Bland-Altman bias between the local velocity values produced by the two techniques indicates quantitative agreement. This preliminary in vivo comparison of respiratory airway CFD and PC MRI of hyperpolarized 129Xe gas demonstrates the feasibility of PC MRI as a technique to validate respiratory CFD and forms the basis for further comprehensive validation studies. This study is therefore a first step in the pathway towards clinical adoption of respiratory CFD

Cross-National Differences in Victimization : Disentangling the Impact of Composition and Context

Varying rates of criminal victimization across countries are assumed to be the outcome of countrylevel structural constraints that determine the supply ofmotivated o¡enders, as well as the differential composition within countries of suitable targets and capable guardianship. However, previous empirical tests of these ‘compositional’ and ‘contextual’ explanations of cross-national di¡erences have been performed upon macro-level crime data due to the unavailability of comparable individual-level data across countries. This limitation has had two important consequences for cross-national crime research. First, micro-/meso-level mechanisms underlying cross-national differences cannot be truly inferred from macro-level data. Secondly, the e¡ects of contextual measures (e.g. income inequality) on crime are uncontrolled for compositional heterogeneity. In this paper, these limitations are overcome by analysing individual-level victimization data across 18 countries from the International CrimeVictims Survey. Results from multi-level analyses on theft and violent victimization indicate that the national level of income inequality is positively related to risk, independent of compositional (i.e. micro- and meso-level) di¡erences. Furthermore, crossnational variation in victimization rates is not only shaped by di¡erences in national context, but also by varying composition. More speci¢cally, countries had higher crime rates the more they consisted of urban residents and regions with lowaverage social cohesion.