13,560 research outputs found

    A multinomial quadrivariate D-vine copula mixed model for meta-analysis of diagnostic studies in the presence of non-evaluable subjects

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    Diagnostic test accuracy studies observe the result of a gold standard procedure that defines the presence or absence of a disease and the result of a diagnostic test. They typically report the number of true positives, false positives, true negatives and false negatives. However, diagnostic test outcomes can also be either non-evaluable positives or non-evaluable negatives. We propose a novel model for the meta-analysis of diagnostic studies in the presence of non-evaluable outcomes, which assumes independent multinomial distributions for the true and non-evaluable positives, and, the true and non-evaluable negatives, conditional on the latent sensitivity, specificity, probability of non-evaluable positives and probability of non-evaluable negatives in each study. For the random effects distribution of the latent proportions, we employ a drawable vine copula that can successively model the dependence in the joint tails. Our methodology is demonstrated with an extensive simulation study and applied to data from diagnostic accuracy studies of coronary computed tomography angiography for the detection of coronary artery disease. The comparison of our method with the existing approaches yields findings in the real data application that change the current conclusions

    NS Fivebrane and Tachyon Condensation

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    We argue that a semi-infinite D6-brane ending on an NS5-brane can be obtained from the condensation of the tachyon on the unstable D9-brane of type IIA theory. The construction uses a combination of the descriptions of these branes as solitons of the worldvolume theory of the D9-brane. The NS5-brane, in particular, involves a gauge bundle which is operator valued, and hence is better thought of as a gerbe.Comment: 20 pages, harvma

    Size reconstructibility of graphs

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    The deck of a graph GG is given by the multiset of (unlabelled) subgraphs {Gv:vV(G)}\{G-v:v\in V(G)\}. The subgraphs GvG-v are referred to as the cards of GG. Brown and Fenner recently showed that, for n29n\geq29, the number of edges of a graph GG can be computed from any deck missing 2 cards. We show that, for sufficiently large nn, the number of edges can be computed from any deck missing at most 120n\frac1{20}\sqrt{n} cards.Comment: 15 page

    Spontaneous Symmetry Breaking in Presence of Electric and Magnetic Charges

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    Starting with the definition of quaternion gauge theory, we have undertaken the study of SU(2)_{e}\times SU(2)_{m}\times U(1)_{e}\times U(1)_{m} in terms of the simultaneous existence of electric and magnetic charges along with their Yang - Mills counterparts. As such, we have developed the gauge theory in terms of four coupling constants associated with four - gauge symmetry SU(2)_{e}\times SU(2)_{m}\times U(1)_{e}\times U(1)_{m}. Accordingly, we have made an attempt to obtain the abelian and non - Abelian gauge structures for the particles carrying simultaneously the electric and magnetic charges (namely dyons). Starting from the Lagrangian density of two SU(2)\times U(1) gauge theories responsible for the existence of electric and magnetic charges, we have discussed the consistent theory of spontaneous symmetry breaking and Higgs mechanism in order to generate the masses. From the symmetry breaking, we have generated the two electromagnetic fields, the two massive vector W^{\pm} and Z^{0} bosons fields and the Higgs scalar fields

    Response to Kamath et al 'A syncretic approach can yield dividends'

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    We welcome the response from Kamath et al. and their insight into the issues and culture within medicine in India, and their thoughts about how to address these issues. We also agree that a drama-based approach is not sufficient on its own to deal with entrenched power issues which affect students adversely. As we have indicated, we believe “a multipronged approach is needed to generate systemic change.” These authors similarly advocate that student mistreatment be dealt with “in a comprehensive manner” including a ‘grievance redressal system’ and other measures to withhold accreditation where there are issues of abuse of power. Nevertheless, we note that Kamath et al. have responded positively to our approach—as a part of that mix—and it would be of great interest to see whether drama-based workshops could support medical students developing embodied acting skills in their institution and whether they may have similar transformative effects. We’d like to refer the authors to an excellent Medical Humanities paper we referenced that outlined drama-based activities in medical education in India: Gupta S, Singh S. Confluence: understanding medical humanities through street theatre. Medical Humanities. 2011;37(2):127-128. Despite the above article, the authors note that medical education in India has not embraced the medical humanities. We would draw a distinction within the medical humanities between activities which are primarily studious (reading literature, studying medical history) and workshops that are based on participative and embodied activity. Our experience has indicated the effectiveness of drama-based workshops in addressing both the cognitive and emotive aspects of harmful practices and we believe that it is the embodied nature of acting skills workshops that is transformative

    Methods for identifying low emissions development options for agriculture

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    Low emissions development strategies (LEDS) are national economic and social development plans that promote sustainable development while reducing GHG emissions. While LEDS programs have helped to mainstream economy-wide planning for low emissions, planning for low emissions agriculture has remained nascent. Low-emissions development (LED) in agriculture acknowledges that the primary purpose of agriculture is to produce food and other goods for human needs, and that climate change mitigation is a secondary goal that should not compromise production. This paper describes a research process and protocol to identify high potential LED options in agriculture at the United States Agency for International Development (USAID). The case study illustrates the steps for the identification and prioritization of LED options including: idea generation, concept development, and evidence building. Each stage is designed to gather and analyze data that specifically enable managers and stakeholders to make informed evaluations. The method gathers not only emission and mitigation information but also food security and income generation data, lending process legitimacy to the research. The incorporation of institutional factors and local contextual systems in the LED concept development stage improves the output credibility and salience. In the final process phase, stakeholders are given an active role in determining the criteria for prioritization and building evidence. The LED option identification and prioritization process illustrates how careful evidence-building can increase the credibility and salience of outputs and legitimacy of the overall results

    Frequency dependence of surface acoustic wave swimming.

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    This is the author accepted manuscript. The final version is available from The Royal Society.Surface acoustic waves (SAWs) are elastic waves that can be excited directly on the surface of piezoelectric crystals using a transducer, leading to their exploitation for numerous technological applications, including for example microfluidics. Recently, the concept of SAW streaming, which underpins SAW microfluidics, was extended to make the first experimental demonstration of 'SAW swimming', where instead of moving water droplets on the surface of a device, SAWs are used as a propulsion mechanism. Using theoretical analysis and experiments, we show that the SAW swimming force can be controlled directly by changing the SAW frequency, due to attenuation and changing force distributions within each SAW streaming jet. Additionally, an optimum frequency exists which generates a maximum SAW swimming force. The SAW frequency can therefore be used to control the efficiency and forward force of these SAW swimming devices. The SAW swimming propulsion mechanism also mimics that used by many microorganisms, where propulsion is produced by a cyclic distortion of the body shape. This improved understanding of SAW swimming provides a test-bed for exploring the science of microorganism swimming, and could bring new insight to the evolutionary significance for the length and beating frequency of swimming microbial flagella.Leverhulme Trust Research Projec

    Culturally safe speech-language supports for First Nations children: Achieving Sustainable Development Goals 3, 4, 8 and 10

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    Purpose: Self-determination is foundational to health and well-being for First Nations people. Colonisation has undermined self-determination and widespread effects are observed as disparities in health and well-being. Chronic middle ear disease is more highly prevalent in First Nations children, is associated with delays in speech and language and lower levels of educational readiness. However, there is a paucity of culturally and linguistically sensitive speech-language assessments and habilitation services globally. Focussing on high-income colonial-settler countries (including United States, Canada, Australia and New Zealand), where health disparities are significant, we aim to discuss the importance of and the challenges in providing culturally safe care to First Nations children with communication disabilities. Result: To be effective, both cultural and linguistic diversity and cultural safety must be considered in all aspects of assessment and intervention. Furthermore, speech-language pathologists must be equipped to work with First Nations children with communication disorders. Conclusion: To optimally support First Nations’ children with communication disabilities, services need to be culturally safe, family-centred and strengths-based. This commentary focuses on the United Nations Sustainable Development Goals (SDGs)3, 4, 8 and 10
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