667 research outputs found

    Chain graph models of multivariate regression type for categorical data

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    We discuss a class of chain graph models for categorical variables defined by what we call a multivariate regression chain graph Markov property. First, the set of local independencies of these models is shown to be Markov equivalent to those of a chain graph model recently defined in the literature. Next we provide a parametrization based on a sequence of generalized linear models with a multivariate logistic link function that captures all independence constraints in any chain graph model of this kind.Comment: Published in at http://dx.doi.org/10.3150/10-BEJ300 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

    Price transmission dynamics for quality‐certified food products: A comparison between conventional and organic fluid milk in Italy

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    Despite the vast number of works investigating price transmission (PT) processes in diverse agrifood markets, very little has been said about quality‐differentiated products. In this paper, we compare the conventional and organic fluid milk sectors in Italy to better understand the economic organization and functioning of one of the most important agrifoods in Italy. Using a unique dataset featuring processor and retail (scanner) prices for the two types of milk, we estimate Momentum‐Threshold Autoregressive models to account for asymmetric price movements in both sectors, but the PT results are eventually symmetric. The Vector Error Correction Model estimations and Impulse Response Functions analysis provide significant insights into the differences between the two markets. [EconLit citations: Q130, Q110, C590]info:eu-repo/semantics/acceptedVersio

    Click Chemistry for the Assembly of Gold Nanorods and Silver Nanoparticles

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    The synthesis of compact nanostructures with highly integratedfunctionalities through the controlled assembly ofnanoparticles (NPs) is potentially of broad interest in researchfields such as drug delivery, multimodal imaging, andelectronic devices. This concept seems to be particularlyimportant in view of the emerging concept of theranostic,according to which both therapeutic and diagnostic capabilitiescan be present in two nanostructures. A key step, however,is how to combine individual nanostructures withoutloosing the original properties

    Looking for Nano- and Microplastics in Meiofauna Using Advanced Methodologies

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    : Meiofauna (body size within 30–1000 µm) are the community of microscopic invertebrates that live at the bottom of marine and freshwater ecosystems and play a key role in the food webs of these environments. Several studies have addressed the adverse effects of anthropic stressors on meiofauna; however, data on the presence and impact of plastic debris in wild meiofaunal organisms are scant. Since the amount of microplastic waste in sediments may surge rapidly, ascertaining the ingestion of these xenobiotics by the abundant micrometazoan community is necessary to understand their potential accumulation in aquatic food webs and their hazard to the health of the ecosystem. The absence of documentation in this regard may be due to the difficulty in detecting the small size of the plastic fragments meiofauna may potentially ingest. To overcome this difficulty, we developed an integrated approach based on different microscopic/spectroscopic techniques suitable for detecting plastic particles of sizes down to 200 nm.Meiofauna (body size within 30–1000 m) are the community of microscopic invertebrates that live at the bottom of marine and freshwater ecosystems and play a key role in the food webs of these environments. Several studies have addressed the adverse effects of anthropic stressors on meiofauna; however, data on the presence and impact of plastic debris in wild meiofaunal organisms are scant. Since the amount of microplastic waste in sediments may surge rapidly, ascertaining the ingestion of these xenobiotics by the abundant micrometazoan community is necessary to understand their potential accumulation in aquatic food webs and their hazard to the health of the ecosystem. The absence of documentation in this regard may be due to the difficulty in detecting the small size of the plastic fragments meiofauna may potentially ingest. To overcome this difficulty, we developed an integrated approach based on different microscopic/spectroscopic techniques suitable for detecting plastic particles of sizes down to 200 nm

    Second-Hand Smoke in a University Campus: Attitudes and Perceptions of Faculty, Staff and Students

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    Purpose: To examine the attitudes and perceptions of faculty, staff and students concerning tobacco policies at a university campus in a tobacco producing state. Methods: A questionnaire was administered to faculty, staff and students to assess knowledge, attitudes and beliefs related to smoking and exposure to second-hand smoke on campus. A 3-wave e-mailing was used to send the questionnaire. Results: A total of 2,914 individuals responded to the questionnaire. Majority (60%) of the participants believed a smoke free policy would be a positive move and could possibly improve the quality of life for the campus community, while not negatively affecting student enrollment status. Conclusion: Implementing a smoke free policy in university campuses in North America could be acceptable to faculty, staff and students and is unlikely to reduce students enrolment. Our findings have the potential to support efforts to implement smoke free policies on university campuses in North America

    Immobilization of Monolayer Protected Lipophilic Gold Nanorods on a Glass Surface

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    We present a novel process of immobilization of gold nanorods (GNRs) on a glass surface. Wedemonstrate that by exploiting monolayer protection of the GNRs, their unusual opticalproperties can be completely preserved. UV–visible spectroscopy and atomic forcemicroscopy analysis are used to reveal the optical and morphological properties of monolayerprotected immobilized lipophilic GNRs, and molecular dynamics simulations are used toelucidate their surface molecule arrangements

    The Influence of Instructional Leadership and Change Leadership on School Achievement in the City of Pekanbaru

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    The purpose of this study was to clarify the impact of instructional leadership (X1) and change leadership (X2) on school achievement (Y). In this study, we used a quantitative approach. Data collected through questionnaires and documents. The survey sample consisted of 91 teachers and 21 schools. The data was analyzed by multiple regression analysis. The results showed that the variable that instructional leadership (X1), change leadership (X2), had an influence on school Achievement (Y), and the regression coefficient was 0.718. The format of the regression equation is: Ŷ = 52.71 + 0.519 X1 + 0.718 X2. The effective contribution of the instructional leadership (X1), change leadership (X2), on school Achievement (Y) variables was 30.22%. Keywords: instructional leadership, change leadership, and school achievement

    Acromion Clavicular Joint Reconstruction with LARS Ligament in Acute Dislocation

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    Background: The acromion clavicular joint dislocations are common injuries of the shoulder. The severity is dependent upon the degree of ligamentous injury. Surgical treatment is typically performed in higher grade acromioclavicular separation with several static and dynamic operative procedures with or without primary ligament replacement. Methods: 47 patients with acute Rockwood type III, IV, and V injuries were treated surgically with LARS reconstruction. The success of technique was evaluated by radiographic outcomes for each patient at every follow-up visit (one,three, 12 months), while to assess pain reduction and clinical evaluation Visual Analogue scale score (VAS) and Constant-Murley score (CMA) was performed, respectively. An One Way Analysis of Variance (Kruskal-Wallis test), a multiple comparison Turket test, or a t-test (Mann-Whitney Rank Sum Test) were used when required. Results: Follow-up radiographs revealed maintenance of anatomical reduction in 41 patients, and no bone erosions has been identified. In short-term joint functional recovery has been observed. Indeed, after 12 months pain on the VAS-scale in all groups decreased significantly (P < 0.05), and the CMS revealed a significant overall improvement (P < 0.05). Conclusion: These data demonstrate that the use of the LARS allows to provide stability to the joint and especially to ensure its natural elasticity, relieving pain and improving joint function already one month post-surgery. Level of evidence: II
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