688 research outputs found
Chain graph models of multivariate regression type for categorical data
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
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
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
Assessment of Nonverbal and Verbal Apraxia in Patients with Parkinson’s Disease
Objective. To assess the presence of nonverbal and verbal apraxia in patients with Parkinson’s disease (PD) and analyze the correlation between these conditions and patient age, education, duration of disease, and PD stage, as well as evaluate the correlation between the two types of apraxia and the frequency and types of verbal apraxic errors made by patients in the sample. Method. This was an observational prevalence study. The sample comprised 45 patients with PD seen at the Movement Disorders Clinic of the Clinical Hospital of Porto Alegre, Brazil. Patients were evaluated using the Speech Apraxia Assessment Protocol and PD stages were classified according to the Hoehn and Yahr scale. Results. The rate of nonverbal apraxia and verbal apraxia in the present sample was 24.4%. Verbal apraxia was significantly correlated with education (p≤0.05). The most frequent types of verbal apraxic errors were omissions (70.8%). The analysis of manner and place of articulation showed that most errors occurred during the production of trill (57.7%) and dentoalveolar (92%) phonemes, consecutively. Conclusion. Patients with PD presented nonverbal and verbal apraxia and made several verbal apraxic errors. Verbal apraxia was correlated with education levels
Looking for Nano- and Microplastics in Meiofauna Using Advanced Methodologies
: 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
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
The Influence of Instructional Leadership and Change Leadership on School Achievement in the City of Pekanbaru
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
Immobilization of Monolayer Protected Lipophilic Gold Nanorods on a Glass Surface
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
- …