314 research outputs found

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    Changing The Definition Of The Kilogram:Insights For Psychiatric Disease Classification

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    Attempts to improve fundamental definitions or classifications are not unique for psychiatry. In a 'hard science' such as metrology-the discipline of measurements in the natural sciences-a major definitional change has been proposed. In 2019, the kilogram will be redefined in terms of a constant of nature instead of a cylinder of platinum-iridium. In this article, we aim to better understand the reasons and procedures for changing definitions by studying the redefinition of the kilogram. In short, the case of the kilogram shows that 1) sometimes the rationale for a redefinition might be clear but the scientific discoveries are not available, and a vast research effort is needed to make progress, 2) progress can be made even in absence of gold standards by reference to the definitions' epistemic aims, and 3) definitions are unlikely to be final as future discoveries might lead to new definitions. These results support the current approach of ongoing, piecemeal revision of psychiatric disease classifications, and stress the importance of robust scientific evidence before changing definitions

    Streambed organic matter controls on carbon dioxide and methane emissions from streams

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    Greenhouse gas (GHG) emissions of carbon dioxide (CO2) and methane (CH4) from streambeds are currently understudied. There is a paucity of research exploring organic matter (OM) controls on GHG production by microbial metabolic activity in streambeds, which is a major knowledge gap given the increased inputs of allochthonous carbon to streams, especially in agricultural catchments. This study aims to contribute to closing this knowledge gap by quantifying how contrasting OM contents in different sediments affect streambed GHG production and associated microbial metabolic activity. We demonstrate, by means of an incubation experiment, that streambed sediments have the potential to produce substantial amounts of GHG, controlled by sediment OM quantity and quality. We observed streambed CO2 production rates that can account for 35% of total stream evasion estimated in previous studies, ranging between 1.4 and 86% under optimal conditions. Methane production varied stronger than CO2 between different geologic backgrounds, suggesting OM quality controls between streambed sediments. Moreover, our results indicate that streambed sediments may produce much more CO2 than quantified to date, depending on the quantity and quality of the organic matter, which has direct implications for global estimates of C fluxes in stream ecosystems

    Psychiatric comorbidity and causal disease models

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    In psychiatry, comorbidity is the rule rather than the exception. Up to 45% of all patients are classified as having more than one psychiatric disorder. These high rates of comorbidity have led to a debate concerning the interpretation of this phenomenon. Some authors emphasize the problematic character of the high rates of comorbidity because they indicate absent zones of rarities. Others consider comorbid conditions to be a validator for a particular reclassification of diseases. In this paper we will show that those at first sight contrasting interpretations of comorbidity are based on similar assumptions about disease models. The underlying ideas are that firstly high rates of comorbidity are the result of the absence of causally defined diseases in psychiatry, and second that causal disease models are preferable to non-causal disease models. We will argue that there are good reasons to seek after causal understanding of psychiatric disorders, but that causal disease models will not rule out high rates of comorbidity-neither in psychiatry, nor in medicine in general. By bringing to the fore these underlying assumptions, we hope to clear the ground for a different understanding of comorbidity, and of models for psychiatric diseases. (C) 2012 Elsevier Inc. All rights reserved.</p

    On the visualization of universal degeneracy in the IMRT problem

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    BACKGROUND: In general, the IMRT optimisation problem possesses many equivalent solutions. This makes it difficult to decide whether a result produced by an IMRT planning algorithm can be further improved, e.g. by adding more beams, or whether it is close to the globally best solution. RESULTS: It is conjectured that the curvature properties of the objective function around any globally optimum dose distribution are universal. This allows an assessment of optimality of dose distributions that are generated by different beam arrangements in a complementary manner to the objective function value alone. A tool to visualize the curvature structure of the objective function is devised. CONCLUSION: In an example case, it is demonstrated how the assessment of the curvature space can indicate the equivalence of rival beam configurations and their proximity to the global optimum

    Patients' perspectives on quality of care for chronic hand eczema:a qualitative study

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    BACKGROUND: Hand eczema (HE) has a significant impact on quality of life and work related activities. Little is known about the patients' perspectives on quality of care for HE. OBJECTIVES: To evaluate the patient perspective of the HE care process in a tertiary referral center. METHODS: Qualitative, semi-structured focus groups were carried out and recorded, transcribed and analysed by an inductive-deductive thematic approach. RESULTS: Fifteen patients participated in four focus groups. Time and attention, together with being listened to and understood by the health care professional, were the most important aspects of care for HE mentioned by participants. Other important insights included: Diagnoses, causes and follow-up of HE were not always clear to the participant; more psychosocial support was needed; participants experienced frequent changes in doctors. Information provided by nurses was valuable, but more individualized advice was needed. CONCLUSIONS: In order to better meet the needs of patients, more explanation should be given about the causes of HE and final diagnosis. Besides focusing on the treatment, it is also important to focus on its impact on the patient and options for psychosocial and peer support should be discussed. Furthermore, the specialized nurse as part of integrated care was emphasized. This article is protected by copyright. All rights reserved
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