1,721,043 research outputs found
Bayesian Plackett--Luce Mixture Models for Partially Ranked Data
Full text linkThe elicitation of an ordinal judgment on multiple alternatives is often required in many psychological
and behavioral experiments to investigate preference/choice orientation of a specific population. The
Plackett–Luce model is one of the most popular and frequently applied parametric distributions to analyze
rankings of a finite set of items. The present work introduces a Bayesian finite mixture of Plackett–Luce
models to account for unobserved sample heterogeneity of partially ranked data. We describe an efficient
way to incorporate the latent group structure in the data augmentation approach and the derivation of existing
maximum likelihood procedures as special instances of the proposed Bayesian method. Inference can
be conducted with the combination of the Expectation-Maximization algorithm for maximum a posteriori
estimation and the Gibbs sampling iterative procedure.We additionally investigate several Bayesian criteria
for selecting the optimal mixture configuration and describe diagnostic tools for assessing the fitness of
ranking distributions conditionally and unconditionally on the number of ranked items. The utility of the
novel Bayesian parametric Plackett–Luce mixture for characterizing sample heterogeneity is illustrated
with several applications to simulated and real preference ranked data. We compare our method with the
frequentist approach and a Bayesian nonparametric mixture model both assuming the Plackett–Luce model
as a mixture component. Our analysis on real datasets reveals the importance of an accurate diagnostic
check for an appropriate in-depth understanding of the heterogenous nature of the partial ranking data
La adquisición de las colocaciones léxicas españolas. El caso de los discentes italófonos
No full textEn el presente trabajo se esboza un análisis de las interferencias lingüísticas que se manifiestan en el uso de las colocaciones españolas por parte de discentes italófonos. Nuestra investigación se basa en los postulados de la fraseología contrastiva y pretende comprobar, mediante el estudio de los materiales auténticos que hemos ido recogiendo a lo largo de nuestra experiencia docente, cómo un alto grado de afinidad entre la L1 y la LE puede constituir un arma de doble filo, al disminuir la atención hacia las divergencias formales que muestran los sistemas colocacionales de los dos idiomas
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dall'andragogia alla glottogeragogia. Gli anziani: Una nuova sfida per l'educazione linguistica.
No full textLa società contemporanea impone alla glottodidattica una riflessione su nuovi pubblici che trasscendono gli ambiti scolastici tradizionali. Uno di questi è rappresentato dalla fascia sociale degli anziani che, almeno nel cosiddetto primo
mondo, vive un vero e proprio “protagonismo demografico”. Il presente saggio si propone di descrivere i confini di un continuum che partendo dai principi andragogici come sviluppo dei principi della pedagogia, approda ad un
insegnamento consapevole delle lingue agli anziani attraverso i nuovi concetti della glottogeragogia
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Quantitative imaging characterization of hypersecreting or nonhypersecreting adrenal adenomas: comparison between iodine-131 norcholesterol uptake and magnetic resonance signal intensity ratios.
No full textObjective: To compare nor-cholesterol (nor-Chol) uptake and magnetic resonance (MR) signal intensity ratios (SIRs) in characterizing adrenal adenomas to differentiate hypersecreting from non-hypersecreting lesions. Methods: We studied 34 patients (14 M and 20 F, mean age 47±15 years) with hypersecreting (n=19) or non-hypersecreting (n=15) adrenal adenomas; all patients underwent iodine-131 nor-Chol scintigraphy and MR studies. Pathology (n=26) or follow-up data (n=8) were obtained. Imaging studies were qualitatively evaluated to calculate diagnostic accuracy of each test; radionuclide studies were also semi-quantitatively evaluated using a 4-point score to measure nor-Chol uptake, while MR scans were quantitatively assessed measuring SIRs of adrenal lesions; imaging data were then compared between hypersecreting and non-hypersecreting adenomas. Results: The diagnostic accuracies of nor-chol (100%) and MR (95%) scans to identify adrenal adenomas were similar; however, while a significantly (p=0.01) higher nor-chol uptake was observed in hypersecreting (2.8+0.5) adenomas compared to non-hypersecreting (2.2+0.6) lesions, no significant differences in SIRs were found in this comparative analysis; in this regard, no significant difference in tumor size (cm) occurred between hypersecreting (2.7+0.5) and non-hypersecreting (3.1+0.9) adenomas. Conclusion: Adrenal scintigraphy using nor-chol and MR are both able to accurately identify cortical adenomas; however, while semi-quantitative analysis of nor-chol uptake is effective to differentiate between hypersecreting and non-hypersecreting adenomas, SIRs evaluation is not useful for this purpose; in particular, the lower nor-chol uptake observed in non-hypersecreting adenomas might reflect the normal hormone synthesis status of these lesions and, thus, regular secretion; this finding could also reflect initial adrenal dysfunction responsible of sub-clinical disorders
Respiratory intensive care units in Italy: A national census and prospective cohort study
No full textBACKGROUND:
In Italy, respiratory intensive care units (RICUs) provide an intermediate level of care between the intensive care unit (ICU) and the general ward for patients with single organ respiratory failure. Because of the lack of official epidemiological data in these units, a two phase study was performed with the aim of describing the work profile in Italian RICUs.
METHODS:
A national survey of RICUs was conducted from January to March 1997 using a questionnaire which comprised over 30 items regarding location, models of service provision, staff, and equipment. The following criteria were necessary for inclusion of a unit in the survey: (1) a nurse to patient ratio ranging from 1:2.5 to 1:4 per shift; (2) availability of adequate continuous non-invasive monitoring; (3) expertise for non-invasive ventilation (NIV) and for intubation in case of NIV failure; (4) physician availability 24 hours a day. Between November 1997 and January 1998 a 3 month prospective cohort study was performed to survey the patient population admitted to the RICUs.
RESULTS:
Twenty six RICUs were included in the study: four were located in rehabilitation centres and 22 in general hospitals. In most, the reported nurse to patient ratio ranged from 1:2 to 1:3, with 36% of units reporting a ratio of 1:4 per shift. During the study period 756 consecutive patients of mean (SD) age 68 (12) years were admitted to the 26 RICUs. The highest proportion (47%) were admitted from emergency departments, 19% from other medical wards, 18% were transferred from the ICU, 13% from specialist respiratory wards, and 2% were transferred following surgery. All but 32 had respiratory failure on admission. The reasons for admission to the RICU were: monitoring for expected clinical instability (n=221), mechanical ventilation (n=473), and weaning (n=59); 586 patients needed mechanical ventilation during their stay in the RICU, 425 were treated with non-invasive techniques as a first line of treatment (374 by non-invasive positive pressure, 51 by iron lung), and 161 underwent invasive mechanical ventilation (63 intubated, 98 tracheostomies). All but 48 patients had chronic respiratory disease, mainly chronic obstructive pulmonary disease (COPD; n=451). More than 70% of patients (n=228) had comorbidity, mainly consisting of heart disorders. The median APACHE II score was 18 (range 1--43). The predicted inpatient mortality risk rate according to the APACHE II equation was 22.1% while the actual inpatient mortality rate was 16%. The mean length of stay in the RICU was 12 (11) days. The outcome in most patients (79.2%) admitted to RICUs was favourable.
CONCLUSIONS:
Italian RICUs are specialised units mainly devoted to the monitoring and treatment of acute on chronic respiratory failure by non-invasive ventilation, but also to weaning from invasive mechanical ventilation. The results of this study provide a useful insight into an increasingly important field of respiratory medicine
- …
