3,090 research outputs found

    Dust and Gas in the disc of HL Tauri: Surface density, dust settling, and dust-to-gas ratio

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    The recent ALMA observations of the disc surrounding HL Tau reveal a very complex dust spatial distribution. We present a radiative transfer model accounting for the observed gaps and bright rings as well as radial changes of the emissivity index. We find that the dust density is depleted by at least a factor 10 in the main gaps compared to the surrounding rings. Ring masses range from 10-100 M_{\oplus} in dust, and, we find that each of the deepest gaps is consistent with the removal of up to 40 M_{\oplus} of dust. If this material has accumulated into rocky bodies, these would be close to the point of runaway gas accretion. Our model indicates that the outermost ring is depleted in millimetre grains compared to the central rings. This suggests faster grain growth in the central regions and/or radial migration of the larger grains. The morphology of the gaps observed by ALMA - well separated and showing a high degree of contrast with the bright rings over all azimuths - indicates that the millimetre dust disc is geometrically thin (scale height \approx 1 au at 100 au) and that a large amount of settling of large grains has already occurred. Assuming a standard dust settling model, we find that the observations are consistent with a turbulent viscosity coefficient of a few 10410^{-4}. We estimate the gas/dust ratio in this thin layer to be of the order of 5 if the initial ratio is 100. The HCO+^+ and CO emission is consistent with gas in Keplerian motion around a 1.7 MM_\odot star at radii from 10120\leq 10 - 120\,au.Comment: 12 pages, 8 figures, published in ApJ, same version as before but with slightly extended discussion on temperature and masses to account for literature published since initial submissio

    Review of best management practices for aquatic vegetation control in stormwater ponds, wetlands, and lakes

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    Auckland Council (AC) is responsible for the development and operation of a stormwater network across the region to avert risks to citizens and the environment. Within this stormwater network, aquatic vegetation (including plants, unicellular and filamentous algae) can have both a positive and negative role in stormwater management and water quality treatment. The situations where management is needed to control aquatic vegetation are not always clear, and an inability to identify effective, feasible and economical control options may constrain management initiatives. AC (Infrastructure and Technical Services, Stormwater) commissioned this technical report to provide information for decision- making on aquatic vegetation management with in stormwater systems that are likely to experience vegetation-related issues. Information was collated from a comprehensive literature review, augmented by knowledge held by the authors. This review identified a wide range of management practices that could be potentially employed. It also demonstrated complexities and uncertainties relating to these options that makes the identification of a best management practice difficult. Hence, the focus of this report was to enable users to screen for potential options, and use reference material provided on each option to confirm the best practice to employ for each situation. The report identifies factors to define whether there is an aquatic vegetation problem (Section 3.0), and emphasises the need for agreed management goals for control (e.g. reduction, mitigation, containment, eradication). Resources to screen which management option(s) to employ are provided (Section 4.0), relating to the target aquatic vegetation, likely applicability of options to the system being managed, indicative cost, and ease of implementation. Initial screening allows users to shortlist potential control options for further reference (Section 5.0). Thirty-five control options are described (Section 5.0) in sufficient detail to consider applicability to individual sites and species. These options are grouped under categories of biological, chemical or physical control. Biological control options involve the use of organisms to predate, infect or control vegetation growth (e.g. classical biological control) or manipulate conditions to control algal growth (e.g. pest fish removal, microbial products). Chemical control options involve the use of pesticides and chemicals (e.g. glyphosate, diquat), or the use of flocculants and nutrient inactivation products that are used to reduce nutrient loading, thereby decreasing algal growth. Physical control options involve removing vegetation or algal biomass (e.g. mechanical or manual harvesting), or setting up barriers to their growth (e.g. shading, bottom lining, sediment capping). Preventative management options are usually the most cost effective, and these are also briefly described (Section 6.0). For example, the use of hygiene or quarantine protocols can reduce weed introductions or spread. Catchment- based practices to reduce sediment and nutrient sources to stormwater are likely to assist in the avoidance of algal and possibly aquatic plant problems. Nutrient removal may be a co-benefit where harvesting of submerged weed biomass is undertaken in stormwater systems. It should also be considered that removal of substantial amounts of submerged vegetation may result in a sudden and difficult-to-reverse s witch to a turbid, phytoplankton dominated state. Another possible solution is the conversion of systems that experience aquatic vegetation issues, to systems that are less likely to experience issues. The focus of this report is on systems that receive significant stormwater inputs, i.e. constructed bodies, including ponds, amenity lakes, wetlands, and highly-modified receiving bodies. However, some information will have application to other natural water bodies

    Resource-dependent evolution of female resistance responses to sexual conflict

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    Sexual conflict can promote the evolution of dramatic reproductive adaptations as well as resistance to its potentially costly effects. Theory predicts that responses to sexual conflict will vary significantly with resource levels-when scant, responses should be constrained by trade-offs, when abundant, they should not. However, this can be difficult to test because the evolutionary interests of the sexes align upon short-term exposure to novel environments, swamping any selection due to sexual conflict. What is needed are investigations of populations that are well adapted to both differing levels of sexual conflict and resources. Here, we used this approach in a long-term experimental evolution study to track the evolution of female resistance to sexual conflict in the fruit fly Drosophila melanogaster. In resource-rich regimes, high-conflict females evolved resistance to continual exposure to males. There was no difference in baseline survival, consistent with the idea that responses evolving under nutritional abundance experienced no trade-offs with resistance. In the poor resource regimes, the ability of high-conflict females to evolve resistance to males was severely compromised and they also showed lower baseline survival than low-conflict females. This suggested high-conflict females traded off somatic maintenance against any limited resistance they had evolved in response to sexual conflict. Overall, these findings provide experimental support for the hypothesis that evolutionary responses to sexual conflict are critically dependent upon resource levels

    Give me a shove I'm falling in love

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    Gift of Dr. Mary Jane Esplen.Piano vocal [instrumentation]The girls were all crazy about Willie Lee [first line]Give me a shove oh! I'm falling in love [first line of chorus]A flat [key]Tempo di valse [tempo]Popular song [form/genre]Woman's portrait in a heart [illustration]De Takacs [graphic artist]Publisher's advertisement on inside front and back cover [note

    A new distance learning national framework for social work continuing education: critical reflections on the first phases of implementation

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    This article utilizes a range of secondary research methodologies to explore the challenges and opportunities that have arisen from the establishment and first years of delivery of a new single and predominantly distant learning national post-qualifying framework. The continuing professional education and learning (CPEL) framework is directly commissioned by the professional regulator Social Care Wales, provided by an alliance of four universities (Bangor, Cardiff, Glyndwr and Swansea) and actively involves employers, practitioners and service users in their development. Critical reflections on the early implementation of the Experienced, Senior and Consultant Programs that contribute to the CPEL framework will help understand the key characteristics, challenges and opportunities post-qualifying education for social workers can bring. The article commences with an analysis of the moves to design a national post-qualification framework that is more accessible, flexible and responsive than the previous patchwork quilt set-up, including an examination of the increased role of distance learning and the teaching methodologies that support it. It then critically summarizes the specific context and developments of the CPEL framework. This is followed by substantive analyses of the key messages. These messages are of the value of; provider collaboration, quality of e-learning experience, employer commitment and student-perceived competence/satisfaction

    Hake Data: problems, solutions and GLM CPUE sensitivity to alternate scenarios

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    The checks carried out on the hake offshore trawl catch and effort data, which provide the basis to split the catches by species and to obtain GLM-standardised CPUE indices of abundance by species, have focused on two separate steps. The first was a re-extract of the data from the original files to check for possible errors in the earlier extracts (this applies to the subset of the data for which size composition information can be unambiguously extracted). The second step was to increase the proportion of the data utilised (and at the same time to check for possible selection biases in the existing sample) by assigning size composition to drags for which this information was not directly available, on the basis of the average for other vessels for which this was available for the area and time at which the fishing concerned took place. The first step revealed a problem with extractions over the last few years which at times for certain vessels had linked the accumulated catch for the day with only the effort for the last trawl of the day, rather than for all trawls that day combined

    Protocol for studying cough frequency in people with pulmonary tuberculosis.

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    INTRODUCTION: Cough is a key symptom of tuberculosis (TB) as well as the main cause of transmission. However, a recent literature review found that cough frequency (number of coughs per hour) in patients with TB has only been studied once, in 1969. The main aim of this study is to describe cough frequency patterns before and after the start of TB treatment and to determine baseline factors that affect cough frequency in these patients. Secondarily, we will evaluate the correlation between cough frequency and TB microbiological resolution. METHODS: This study will select participants with culture confirmed TB from 2 tertiary hospitals in Lima, Peru. We estimated that a sample size of 107 patients was sufficient to detect clinically significant changes in cough frequency. Participants will initially be evaluated through questionnaires, radiology, microscopic observation drug susceptibility broth TB-culture, auramine smear microscopy and cough recordings. This cohort will be followed for the initial 60 days of anti-TB treatment, and throughout the study several microbiological samples as well as 24 h recordings will be collected. We will describe the variability of cough episodes and determine its association with baseline laboratory parameters of pulmonary TB. In addition, we will analyse the reduction of cough frequency in predicting TB cure, adjusted for potential confounders. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the ethics committees at each participating hospital in Lima, Peru, Asociación Benéfica PRISMA in Lima, Peru, the Universidad Peruana Cayetano Heredia in Lima, Peru and Johns Hopkins University in Baltimore, USA. We aim to publish and disseminate our findings in peer-reviewed journals. We also expect to create and maintain an online repository for TB cough sounds as well as the statistical analysis employed

    What do children think of their own bilingualism? Exploring bilingual children’s attitudes and perceptions

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    Aims and objectives: This paper explores children’s experiences and perceptions of their own bilingualism in two contexts in Scotland, UK: a primary school with a high proportion of children using a language other than English at home; and a primary school where the language of instruction is an indigenous, minority language, Gaelic. Methodology: The paper draws upon data gathered from multiple qualitative methods, including interviews, group activities and discussion, with both children and their parents. The data in this paper draw upon a broader interdisciplinary project exploring children’s experiences of bilingualism. Ethics were duly considered. Data and analysis: Data were gathered from 27 children and 11 parents. Data were coded and analysed using thematic analysis. Comparison between contexts was of particular interest for this article. Findings: This paper highlights the importance of research with children in order to gain an insight into their experiences and perceptions of their own bilingualism. In particular, our findings illustrate how children’s language learning is encouraged and supported by children’s connections with others and the fundamental role of family (particularly parents/carers) and diverse community-based support systems (which encompass a wide range of individuals and community groups) in order to develop active bilingualism. Originality: This paper addresses a research gap in a largely quantitative field, by adopting a qualitative approach to explore children’s experiences and perceptions of their own bilingualism. A qualitative approach facilitates attention to complexity and the participants’ own meanings and understandings. Significance: The paper highlights the value of research with children in order to explore their views and perspectives. In particular, qualitative research methodologies, where children’s experiences are central to understanding the research phenomenon, and to facilitating the exploration of the range of complex issues that interact with a child’s bilingualism.Output Status: Forthcoming/Available Onlin

    Oral activated charcoal prevents experimental cerebral malaria in mice and in a randomized controlled clinical trial in man did not interfere with the pharmacokinetics of parenteral artesunate.

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    BACKGROUND: Safe, cheap and effective adjunct therapies preventing the development of, or reducing the mortality from, severe malaria could have considerable and rapid public health impact. Oral activated charcoal (oAC) is a safe and well tolerated treatment for acute poisoning, more recently shown to have significant immunomodulatory effects in man. In preparation for possible efficacy trials in human malaria, we sought to determine whether oAC would i) reduce mortality due to experimental cerebral malaria (ECM) in mice, ii) modulate immune and inflammatory responses associated with ECM, and iii) affect the pharmacokinetics of parenteral artesunate in human volunteers. METHODS/PRINCIPAL FINDINGS: We found that oAC provided significant protection against P. berghei ANKA-induced ECM, increasing overall survival time compared to untreated mice (p<0.0001; hazard ratio 16.4; 95% CI 6.73 to 40.1). Protection from ECM by oAC was associated with reduced numbers of splenic TNF(+) CD4(+) T cells and multifunctional IFNgamma(+)TNF(+) CD4(+) and CD8(+) T cells. Furthermore, we identified a whole blood gene expression signature (68 genes) associated with protection from ECM. To evaluate whether oAC might affect current best available anti-malarial treatment, we conducted a randomized controlled open label trial in 52 human volunteers (ISRCTN NR. 64793756), administering artesunate (AS) in the presence or absence of oAC. We demonstrated that co-administration of oAC was safe and well-tolerated. In the 26 subjects further analyzed, we found no interference with the pharmacokinetics of parenteral AS or its pharmacologically active metabolite dihydroartemisinin. CONCLUSIONS/SIGNIFICANCE: oAC protects against ECM in mice, and does not interfere with the pharmacokinetics of parenteral artesunate. If future studies succeed in establishing the efficacy of oAC in human malaria, then the characteristics of being inexpensive, well-tolerated at high doses and requiring no sophisticated storage would make oAC a relevant candidate for adjunct therapy to reduce mortality from severe malaria, or for immediate treatment of suspected severe malaria in a rural setting. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN64793756
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