Synchronous Task Control and Synchronous Barriers

The ARG has asked the IRTAW community to consider two issues that have arisen recently as part of their maintenance of the Ada language. First we consider the extent to which Synchronous Task Control should be used by concurrent tasks. And then the issue of whether, or not, Synchronous Barriers are a natural part of the Ravenscar profile

Hypoxaemia in patients with pulmonary arterial hypertension during simulated air travel

SummaryBackgroundRecent air travel recommendations suggest patients with precapillary pulmonary hypertension (PCPH) in New York Heart Association (NYHA) functional class 3 and 4 should have in-flight oxygen without the need for pre-flight testing. However it remains unclear as to how best to determine patients fitness to fly.MethodsThis study (i) investigates the effect of hypoxic challenge testing (HCT) on the arterial oxygen levels in a cohort of 36 patients with PCPH and (ii) compares the relative frequency with which FC and HCT predict the requirement for in-flight oxygen.ResultsThe degree of arterial hypoxaemia induced by HCT (fall in partial pressure of oxygen in arterial blood (PaO2) 2.36 kPa, 95% CI 2.06–2.66 kPa) was similar to the drop observed in other published studies of chronic respiratory diseases.Following current air travel recommendations based on FC, 25 patients of the cohort would require in-flight oxygen whilst 10 subjects failed the HCT. Fourteen subjects had flown post-diagnosis. Of these, nine subjects should have had in-flight oxygen based on FC but were asymptomatic without. Also one who passed the HCT had developed symptoms during the flight whilst three who failed the HCT were asymptomatic flying without in-flight oxygen.ConclusionsHypoxaemia induced by simulated air travel in patients with PCPH is similar to that seen in published studies of patients with other chronic respiratory diseases. HCT failed to predict correctly who had developed symptoms during an aircraft flight in a significant minority of the study subjects. Similarly guidelines based on functional class result in a major increase in the proportion of patients being advised to use oxygen, many of whom had been asymptomatic on previous flights without it. More work is required to improve prediction of need for in-flight oxygen in patients with PCPH

HIV Self-Testing among Men Who Have Sex with Men (MSM) in the UK: A Qualitative Study of Barriers and Facilitators, Intervention Preferences and Perceived Impacts

INTRODUCTION: Innovative strategies, such as HIV self-testing (HIVST), could increase HIV testing rates and diagnosis. Evidence to inform the design of an HIVST intervention in the UK is scarce with very little European data on this topic. This study aims to understand values and preferences for HIVST interventions targeting MSM in the UK. We explore the acceptability of HIVST among MSM in the context of known barriers and facilitators to testing for HIV; assess preferences for, and the concerns about, HIVST. METHODS: Six focus group discussions (FGD) were conducted with 47 MSM in London, Manchester and Plymouth. HIVST as a concept was discussed and participants were asked to construct their ideal HIVST intervention. OraQuickTM and BioSureTM kits were then demonstrated and participants commented on procedure, design and instructions. FGDs were recorded and transcribed verbatim, then analysed thematically. RESULTS: Convenience and confidentiality of HIVST was seen to facilitate testing. Issues with domestic privacy problematised confidentiality. HIVST kits and instructions were thought to be unnecessarily complicated, and did not cater to the required range of abilities. The window period was the most important element of an HIVST, with strong preference for 4th generation testing. Kits which used a blood sample were more popular than those using saliva due to higher perceived accuracy although phobia of needles and/or blood meant some would only access HIVST if a saliva sample option was available. A range of access options was important to maintain convenience and privacy. HIVST kits were assumed to increase frequency of testing, with concerns related to the dislocation of HIVST from sexual health care pathways and services. DISCUSSION: Utility of HIVST arises from relatively high levels of confidentiality and convenience. Until 4th generation assays are available HIVST will be seen as supplementary in a UK context

Improved traceability in seafood supply chains is achievable by minimising vulnerable nodes in processing and distribution networks

Seafood is a globally traded commodity, often involving complex supply chains which have varying degrees of traceability. A robust traceability system for seafood supply chains enables the collection and communication of key information about catch and fisheries origins vital for assurance of the legality and sustainability of seafood products. End-to-end traceability is increasingly demanded by retailers, consumers, NGOs and regulatory bodies to ensure food safety, deter IUU fishing and verify sustainable and ethical credentials. Here, we map three UK seafood supply chains and evaluate traceability performance in: Dover sole landed in the south west of England, North-East Atlantic (NEA) mackerel landed at Peterhead, Scotland, and brown crab and European lobster, landed at Bridlington, England. Through a comparative analysis of traceability performance, this study suggests improvements to the technologies, processes, and systems for traceability in the seafood sector. The application of monitoring technologies and regulatory changes across the sector have increased traceability and potentially reduced instances of IUU fishing. While shorter supply chains are more likely to achieve end-to-end traceability, vulnerable nodes in processing and distribution networks may result in a loss of seafood traceability. While traceability systems may provide sustainability information on seafood, a high level of traceability performance does not necessarily equate to a sustainable source fishery. Encouragingly, while UK seafood supply chains are meeting minimum regulatory requirements for traceability, in the present study, many stakeholders have indicated ambitions towards traceability best practice in order to provide confidence and trust in the UK fishing industry

Cellular mechanisms underlying Pax3-related neural tube defects and their prevention by folic acid

Neural tube defects (NTDs), including spina bifida and anencephaly, are among the most common birth defects worldwide, but their underlying genetic and cellular causes are not well understood. Some NTDs are preventable by supplemental folic acid. However, despite widespread use of folic acid supplements and implementation of food fortification in many countries, the protective mechanism is unclear. Pax3 mutant (splotch; Sp2H) mice provide a model in which NTDs are preventable by folic acid and exacerbated by maternal folate deficiency. Here, we found that cell proliferation was diminished in the dorsal neuroepithelium of mutant embryos, corresponding to the region of abolished Pax3 function. This was accompanied by premature neuronal differentiation in the prospective midbrain. Contrary to previous reports, we did not find evidence that increased apoptosis could underlie failed neural tube closure in Pax3 mutant embryos, nor that inhibition of apoptosis could prevent NTDs. These findings suggest that Pax3 functions to maintain the neuroepithelium in a proliferative, undifferentiated state, allowing neurulation to proceed. NTDs in Pax3 mutants were not associated with abnormal abundance of specific folates and were not prevented by formate, a one-carbon donor to folate metabolism. Supplemental folic acid restored proliferation in the cranial neuroepithelium. This effect was mediated by enhanced progression of the cell cycle from S to G2 phase, specifically in the Pax3 mutant dorsal neuroepithelium. We propose that the cell-cycle-promoting effect of folic acid compensates for the loss of Pax3 and thereby prevents cranial NTDs

Using Subsystem MT2 for Complete Mass Determinations in Decay Chains with Missing Energy at Hadron Colliders

We propose to use the MT2 concept to measure the masses of all particles in SUSY-like events with two unobservable, identical particles. To this end we generalize the usual notion of MT2 and define a new MT2(n,p,c) variable, which can be applied to various subsystem topologies, as well as the full event topology. We derive analytic formulas for its endpoint MT2{max}(n,p,c) as a function of the unknown test mass Mc of the final particle in the subchain and the transverse momentum pT due to radiation from the initial state. We show that the endpoint functions MT2{max}(n,p,c)(Mc,pT) may exhibit three different types of kinks and discuss the origin of each type. We prove that the subsystem MT2(n,p,c) variables by themselves already yield a sufficient number of measurements for a complete determination of the mass spectrum (including the overall mass scale). As an illustration, we consider the simple case of a decay chain with up to three heavy particles, X2 -> X1 -> X0, which is rather problematic for all other mass measurement methods. We propose three different MT2-based methods, each of which allows a complete determination of the masses of particles X0, X1 and X2. The first method only uses MT2(n,p,c) endpoint measurements at a single fixed value of the test mass Mc. In the second method the unknown mass spectrum is fitted to one or more endpoint functions MT2{max}(n,p,c)(Mc,pT) exhibiting a kink. The third method is hybrid, combining MT2 endpoints with measurements of kinematic edges in invariant mass distributions. As a practical application of our methods, we show that the dilepton W+W- and tt-bar samples at the Tevatron can be used for an independent determination of the masses of the top quark, the W boson and the neutrino, without any prior assumptions.Comment: 47 pages, 9 figures. revised version, published in JHEP. Major addition: a new appendix with the complete set of formulas for the MT2 endpoints as functions of the upstream transverse momentum pT and test mass M

Retinoic acid accelerates the specification of enteric neural progenitors from in-vitro-derived neural crest

The enteric nervous system (ENS) is derived primarily from the vagal neural crest, a migratory multipotent cell population emerging from the dorsal neural tube between somites 1 and 7. Defects in the development and function of the ENS cause a range of enteric neuropathies, including Hirschsprung disease. Little is known about the signals that specify early ENS progenitors, limiting progress in the generation of enteric neurons from human pluripotent stem cells (hPSCs) to provide tools for disease modeling and regenerative medicine for enteric neuropathies. We describe the efficient and accelerated generation of ENS progenitors from hPSCs, revealing that retinoic acid is critical for the acquisition of vagal axial identity and early ENS progenitor specification. These ENS progenitors generate enteric neurons in vitro and, following in vivo transplantation, achieved long-term colonization of the ENS in adult mice. Thus, hPSC-derived ENS progenitors may provide the basis for cell therapy for defects in the ENS

Vascularisation is not necessary for gut colonisation by enteric neural crest cells

The vasculature and nervous system share striking similarities in their networked, tree-like architecture and in the way they are super-imposed in mature organs. It has previously been suggested that the intestinal microvasculature network directs the migration of enteric neural crest cells (ENCC) along the gut to promote the formation of the enteric nervous system (ENS). To investigate the inter-relationship of migrating ENCC, ENS formation and gut vascular development we combined fate-mapping of ENCC with immunolabelling and intravascular dye injection to visualise nascent blood vessel networks. We found that the enteric and vascular networks initially had very distinct patterns of development. In the foregut, ENCC migrated through areas devoid of established vascular networks. In vessel-rich areas, such as the midgut and hindgut, the distribution of migrating ENCC did not support the idea that these cells followed a pre-established vascular network. Moreover, when gut vascular development was impaired, either genetically in Vegfa120/120 or Tie2-Cre;Nrp1fl/- mice or using an in vitro Wnt1-Cre;Rosa26Yfp/+ mouse model of ENS development, ENCC still colonised the entire length of the gut, including the terminal hindgut. These results demonstrate that blood vessel networks are not necessary to guide migrating ENCC during ENS development. Conversely, in miRet51 mice, which lack ENS in the hindgut, the vascular network in this region appeared to be normal suggesting that in early development both networks form independently of each other

Sparticle masses in deflected mirage mediation

We discuss the sparticle mass patterns that can be realized in deflected mirage mediation scenario of supersymmetry breaking, in which the moduli, anomaly, and gauge mediations all contribute to the MSSM soft parameters. Analytic expression of low energy soft parameters and also the sfermion mass sum rules are derived, which can be used to interpret the experimentally measured sparticle masses within the framework of the most general mixed moduli-gauge-anomaly mediation. Phenomenological aspects of some specific examples are also discussed.Comment: 43 pages, 17 figures, references adde

Femtosecond Yb:YCOB laser pumped by narrow-stripe laser diode and passively modelocked using ion implanted saturable-absorber mirror

The authors present, what they believe to be, the first femtosecond Yb:YCOB laser, pumped by a low-power, narrow-stripe laser diode. To facilitate modelocking, high-energy oxygen ion implantation of the saturable absorber is employed. 210 fs pulse generation at 16 mW average output power for 140 mW incident pump power is reporte