4,436 research outputs found

    Erratum: The chemistry of transient molecular cloud cores

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    We assume that some, but not all, of the structure observed in molecular clouds is associated with transient features which are not bound by self-gravity. We investigate the chemistry of a transient density fluctuation, with properties similar to those of a core within a molecular cloud. We run a multipoint chemical code through a core's condensation from a diffuse medium to its eventual dispersion, over a period of āˆ¼1 Myr. The dynamical description adopted for our study is based on an understanding of a particular mechanism, involving slow-mode wave excitation, for transient structure formation which so far has been studied in detail only with plane-parallel models in which self-gravity has not been included. We find a significant enhancement of the chemical composition of the core material on its return to diffuse conditions, whilst the expansion of the core as it disperses moves this material out to large distances from the core centre. This process transports molecular species formed in the high-density regions out into the diffuse medium. Chemical enrichment of the cloud as a whole also occurs, as other cores of various sizes, life-spans and separations evolve throughout. Enrichment is strongly affected by freeze-out on to dust grains, which takes place in high-density, high visual extinction regions. As the core disperses after reaching its peak density and the visual extinction drops below a critical value, grain mantles are evaporated back into the gas phase, initiating more chemistry. The influence of the sizes, masses and cycle periods of cores will be large both for the level of chemical enrichment of a dark cloud and ultimately for the low-mass star formation rate. The cores in which stars form are almost certainly bound by their self-gravity and are not transient in the sense that the cores on which most of our study is focused are transient. Obviously, enrichment of the chemistry of low-density material will not take place if self-gravity prevents the re-expansion of a core. We also consider the case of a self-gravitating core, by holding its peak density conditions for a further 0.4 Myr. We find that the differences near the peak densities between transient and gravitationally bound cores are generally small, and the resultant column densities for objects near the peak densities do not provide definitive criteria for discriminating between transient and bound cores. However, increases in fractional abundances due to reinjection of mantle-borne species may provide a criterion for detection of a non-bound core

    The effect of alpha(+)-thalassaemia on the incidence of malaria and other diseases in children living on the coast of Kenya

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    BACKGROUND: The alpha-thalassaemias are the commonest genetic disorders of humans. It is generally believed that this high frequency reflects selection through a survival advantage against death from malaria; nevertheless, the epidemiological description of the relationships between alpha-thalassaemia, malaria, and other common causes of child mortality remains incomplete. METHODS AND FINDINGS: We studied the alpha+-thalassaemia-specific incidence of malaria and other common childhood diseases in two cohorts of children living on the coast of Kenya. We found no associations between alpha+-thalassaemia and the prevalence of symptomless Plasmodium falciparum parasitaemia, the incidence of uncomplicated P. falciparum disease, or parasite densities during mild or severe malaria episodes. However, we found significant negative associations between alpha+-thalassaemia and the incidence rates of severe malaria and severe anaemia (haemoglobin concentration < 50 g/l). The strongest associations were for severe malaria anaemia (> 10,000 P. falciparum parasites/mul) and severe nonmalaria anaemia; the incidence rate ratios and 95% confidence intervals (CIs) for alpha+-thalassaemia heterozygotes and homozygotes combined compared to normal children were, for severe malaria anaemia, 0.33 (95% CI, 0.15,0.73; p = 0.006), and for severe nonmalaria anaemia, 0.26 (95% CI, 0.09,0.77; p = 0.015). CONCLUSIONS: Our observations suggest, first that selection for alpha+-thalassaemia might be mediated by a specific effect against severe anaemia, an observation that may lead to fresh insights into the aetiology of this important condition. Second, although alpha+-thalassaemia is strongly protective against severe and fatal malaria, its effects are not detectable at the level of any other malaria outcome; this result provides a cautionary example for studies aimed at testing malaria interventions or identifying new malaria-protective genes

    Knowledge Wars: Professionalisation, Organisational Justice and Competing Knowledge Paradigms in British Policing

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    The professionalisation agenda in British policing is being driven by the College of Policing. Whilst there are a number of definitions of professionalism (Sklansky, 2014), the basic tenets of a professional organisation are that the employees follow a code of ethics, there is a commitment to use expert knowledge and that there is an element of self-regulation. Within the professionalisation agenda for the British police there are a number of strands. These include the implementation of a police code of ethics, the development of a police education qualification framework (PEQF) and wide support of police and academic collaborations to ensure police practice becomes increasingly evidence based. This chapter focuses on the latter strand of work, evidence based policing (EBP), particularly as there has been extensive debate in both the academic and policing fields about the extent to which police officers are both supportive and understanding of this concept and the extent to which they feel involved in EBP at all stages of the process (Fleming and Wingrove, 2017). In doing so, the chapter will seek to explore some of the potential issues which arise in respect of EBP by using the theory and principles of organisational justice. This will be used to explore the changing conceptualisation of knowledge within police organisations and the link this has with the professionalisation of policing. We will attempt to do this firstly, by exploring the concept and principles of organisational justice and applying this to the context of policing, EBP and knowledge work. Secondly, we will explore what we mean by knowledge in a police context and, thirdly, we will examine the potential to apply the concept of organisational justice to current views on the constitution of knowledge and knowledge outputs in the modern policing milie

    A systematic examination of preoperative surgery warm-up routines

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    Recent evidence indicates that a preoperative warm-up is a potentially useful tool in facilitating performance. But what factors drive such improvements and how should a warm-up be implemented?In order to address these issues, we adopted a two-pronged approach: (1) we conducted a systematic review of the literature to identify existing studies utilising preoperative simulation techniques; (2) we performed task analysis to identify the constituent parts of effective warm-ups. We identified five randomised control trials, four randomised cross-over trials and four case series. The majority of these studies reviewed surgical performance following preoperative simulation relative to performance without simulation.Four studies reported outcome measures in real patients and the remainder reported simulated outcome measures. All but one of the studies found that preoperative simulation improves operative outcomes-but this improvement was not found across all measured parameters. While the reviewed studies had a number of methodological issues, the global data indicate that preoperative simulation has substantial potential to improve surgical performance. Analysis of the task characteristics of successful interventions indicated that the majority of these studies employed warm-ups that focused on the visual motor elements of surgery. However, there was no theoretical or empirical basis to inform the design of the intervention in any of these studies.There is an urgent need for a more rigorous approach to the development of "warm-up" routines if the potential value of preoperative simulation is to be understood and realised. We propose that such interventions need to be grounded in theory and empirical evidence on human motor performance

    A nested PCR assay to avoid false positive detection of the microsporidian enterocytozoon hepatopenaei (EHP) in environmental samples in shrimp farms

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    PublishedJournal ArticleĀ© 2016 Jaroenlak et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) is an important disease of cultivated shrimp. Heavy infections may lead to retarded growth and unprofitable harvests. Existing PCR detection methods target the EHP small subunit ribosomal RNA (SSU rRNA) gene (SSU-PCR). However, we discovered that they can give false positive test results due to cross reactivity of the SSU-PCR primers with DNA from closely related microsporidia that infect other aquatic organisms. This is problematic for investigating and monitoring EHP infection pathways. To overcome this problem, a sensitive and specific nested PCR method was developed for detection of the spore wall protein (SWP) gene of EHP (SWP-PCR). The new SWP-PCR method did not produce false positive results from closely related microsporidia. The first PCR step of the SWP-PCR method was 100 times (104 plasmid copies per reaction vial) more sensitive than that of the existing SSU-PCR method (106 copies) but sensitivity was equal for both in the nested step (10 copies). Since the hepatopancreas of cultivated shrimp is not currently known to be infected with microsporidia other than EHP, the SSU-PCR methods are still valid for analyzing hepatopancreatic samples despite the lower sensitivity than the SWP-PCR method. However, due to its greater specificity and sensitivity, we recommend that the SWP-PCR method be used to screen for EHP in feces, feed and environmental samples for potential EHP carriers.OI acknowledges support from Agricultural Research Development Agency under project CRP5905020530 and Mahidol University. KS received funding from National Research Council Thailand, Division of Plan Administration and Research Budget/2557-79. PJ is supported by the Science Achievement Scholarship of Thailand (SAST). GDS acknowledges support of DG SANCO of the European Commission, and the UK Department of Environment, Food and Rural Affairs under project FB002. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    New Paradigms to Help Solve the Global Aquaculture Disease Crisis.

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    Published onlineJournal ArticleThis is the final version of the article. Available from Public Library of Science via the DOI in this record.n/aThe authors (GDS, KS) acknowledge funding administered by the British Council under the Newton Fund Researcher Links Programme, for a UK-Thailand bilateral workshop entitled "Scientific, technological and social solutions for sustainable aquaculture in Thailand: a key player in global aquatic food supply," Bangkok, March 2016. Further funding support is acknowledged from the European Commission (EC) and the UK Department for Environment, Food and Rural Affairs (Defra) under contracts C6928 and FB002 (to GDS and DB); from the Royal Society under a University Research Fellowship (to BAPW); and to the Agricultural Research Development Agency (ARDA) and National Research Council of Thailand (NRCT) (to KS, TWF, and OI). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

    Lower limb kinematic, kinetic and spatial-temporal gait data for healthy adults using a self-paced treadmill

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    Through gait analysis, gait phases can be identified, the kinematic and kinetic parameters of human gait events can be determined, and quantitative evaluation can be undertaken. This data article is the first to report a comprehensive data set on a large cohort of healthy participants. Individual strides were determined from vertical force data and all kinematics and kinetic data separated into strides. Local minima and maxima were determined respectively for each anatomical region and the mean calculated for twenty of the 25 strides. When twenty strides were not available the mean of ten strides was used. Stride data were time normalised so one stride was represented by 100%. In addition to the local maxima and minima, the kinematic- and kinetic-time curves were explored and used to determine the mean kinematic-time and kinetic-time curves across all trials and participants (āˆ¼1800 gait cycles) to provide meanĀ±sd kinematic- and kinetic-time curves for each of the anatomical regions

    Occupational lung diseases among former goldminers in two labour sending areas

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    Objectives. To compare and contrast the prevalence ofĀ pneumoconiosis in two groups of former migrantĀ mineworkers in southern Africa, and to examine theĀ effectiveness of the South African compensation system forĀ occupational lung diseases.Design. Comparison of two cross-sectional studies andĀ follow-up data on compensation results.Setting. The village of Thamaga, Botswana and the ruralĀ area of Libode, Eastern Cape, South Africa.Subjects. Two hundred and thirty-four former undergroundĀ mineworkers in Thamaga, and 238 in Libode.Ā Main outcome measures. Prevalence and severity ofĀ pneumoconiosis, prevalence of radiological signs ofĀ tuberculosis (TB), Medical Bureau for OccupationalĀ Diseases (MBOD) certification committee decisions, andĀ compensation results.Results. Prevalence of pneumoconiosis ā‰„Ā 2/ 1 was 15.4% inĀ Libode and 13.6% in Thamaga. Significantly more LibodeĀ than Thamaga subjects (51.1% versus 29.0%) reported pastĀ TB treatment Radiological signs of pulmonary TB were alsoĀ more prevalent in Libode (33.3% v. 23.9%). Twenty-six perĀ cent of Libode men and 16.1% of Thamaga men were certified with compensable disease. Libode payments wereĀ finalised within 30 months, whereas Thamaga cases onlyĀ began receiving payments 52 months after medical Ā examination, with 11 cases still pending 66 months after medical examination.Conclusion. There was a high prevalence of pneumoconiosisĀ in both study groups. Many men were eligible forĀ compensation but were previously uncompensated. TheĀ higher rate of compensable disease in the Libode group mayĀ relate to the higher prevalence of TB, as well as more activeĀ follow-up by the study group, including a large number ofĀ appeals. Socio-political changes in South Africa between 1994Ā and 1996 may also have influenced compensation results
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