Estimation and diagnostics for heteroscedastic nonlinear regression models based on scale mixtures of skew-normal distributions

An extension of some standard likelihood based procedures to heteroscedastic nonlinear regression models under scale mixtures of skew-normal (SMSN) distributions is developed. This novel class of models provides a useful generalization of the heteroscedastic symmetrical nonlinear regression models (Cysneiros et al., 2010), since the random term distributions cover both symmetric as well as asymmetric and heavy-tailed distributions such as skew-t, skew-slash, skew-contaminated normal, among others. A simple EM-type algorithm for iteratively computing maximum likelihood estimates of the parameters is presented and the observed information matrix is derived analytically. In order to examine the performance of the proposed methods, some simulation studies are presented to show the robust aspect of this flexible class against outlying and influential observations and that the maximum likelihood estimates based on the EM-type algorithm do provide good asymptotic properties. Furthermore, local influence measures and the one-step approximations of the estimates in the case-deletion model are obtained. Finally, an illustration of the methodology is given considering a data set previously analyzed under the homoscedastic skew-t nonlinear regression model. (C) 2012 Elsevier B.V. All rights reserved.

Representations of workplace psychological harassment in print news media

OBJECTIVE: To analyze discourses on workplace psychological harassment in print media. METHODOLOGICAL PROCEDURES: Documental study on workplace psychological harassment that analyzed news stories published in three major newspapers of the State of Sao Paulo (southeastern Brazil) between 1990 and 2008. Discourse analysis was performed to identify discursive practices that reflect the phenomenon of psychological harassment in today's society, explanations for its occurrence and impact on workers' health. RESULT ANALYSIS: This theme emerged in the media through the dissemination of books, academic research production and laws. It was initially published in general news then in jobs and/or business sections. Discourses on compensation and precautionary business practices and coping strategies are widespread. Health-related aspects are foregone under the prevailing money-based rationale. Corporate cultures are permissive regarding psychological harassment and conflicts are escalated while working to achieve goals and results. Indifference, embarrassment, ridicule and demean were common in the news stories analyzed. CONCLUSIONS: The causal explanations of workplace harassment tend to have a psychological interpretation with emphasis on individual and behavioral characteristics, and minimizing a collective approach. The discourses analyzed trivialized harassment by creating caricatures of the actors involved. People apprehend its psychological content and stigmatization which contributes to making workplace harassment an accepted practice and trivializing work-related violence.

Identification of literary movements using complex networks to represent texts

The use of statistical methods to analyze large databases of text has been useful in unveiling patterns of human behavior and establishing historical links between cultures and languages. In this study, we identified literary movements by treating books published from 1590 to 1922 as complex networks, whose metrics were analyzed with multivariate techniques to generate six clusters of books. The latter correspond to time periods coinciding with relevant literary movements over the last five centuries. The most important factor contributing to the distinctions between different literary styles was the average shortest path length, in particular the asymmetry of its distribution. Furthermore, over time there has emerged a trend toward larger average shortest path lengths, which is correlated with increased syntactic complexity, and a more uniform use of the words reflected in a smaller power-law coefficient for the distribution of word frequency. Changes in literary style were also found to be driven by opposition to earlier writing styles, as revealed by the analysis performed with geometrical concepts. The approaches adopted here are generic and may be extended to analyze a number of features of languages and cultures.

Description of Two New Sand Fly Species Related to Nyssomyia antunesi (Diptera, Psychodidae, Phlebotominae)

Both sexes of two new Brazilian phlebotomine sand flies of the genus Nyssomyia Barretto 1962 [= Lutzomyia (Nyssomyia) sensu Barretto], Nyssomyia delsionatali n. sp. and Nyssomyia urbinattii n. sp., presenting close affinity with Nyssomyia antunesi (Coutinho), are described and illustrated. N. delsionatali n. sp was captured on the edge of a riparian Amazonian forest on the Juruena river in the northwest of Mato Grosso state and N. urbinattii n. sp in a riparian Amazonian forest on the Teles Pires river between Mato Grosso and Para states. Some measurements of both sexes of N. antunesi and illustration of the male genitalia and the female spermathecae as well as an identi_cation key for males and females of the genus Nyssomyia are provided.

Development and application of a GC system for NMHC analyses of air samples from the CARIBIC aircraft project

The subject of this thesis is the development of a Gaschromatography (GC) system for non-methane hydrocarbons (NMHCs) and measurement of samples within the project CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container, www.caribic-atmospheric.com). Air samples collected at cruising altitude from the upper troposphere and lowermost stratosphere contain hydrocarbons at low levels (ppt range), which imposes substantial demands on detection limits. Full automation enabled to maintain constant conditions during the sample processing and analyses. Additionally, automation allows overnight operation thus saving time. A gas chromatography using flame ionization detection (FID) together with the dual column approach enables simultaneous detection with almost equal carbon atom response for all hydrocarbons except for ethyne. The first part of this thesis presents the technical descriptions of individual parts of the analytical system. Apart from the sample treatment and calibration procedures, the sample collector is described. The second part deals with analytical performance of the GC system by discussing tests that had been made. Finally, results for measurement flight are assessed in terms of quality of the data and two flights are discussed in detail. Analytical performance is characterized using detection limits for each compound, using uncertainties for each compound, using tests of calibration mixture conditioning and carbon dioxide trap to find out their influence on analyses, and finally by comparing the responses of calibrated substances during period when analyses of the flights were made. Comparison of both systems shows good agreement. However, because of insufficient capacity of the CO2 trap the signal of one column was suppressed due to breakthroughed carbon dioxide so much that its results appeared to be unreliable. Plausibility tests for the internal consistency of the given data sets are based on common patterns exhibited by tropospheric NMHCs. All tests show that samples from the first flights do not comply with the expected pattern. Additionally, detected alkene artefacts suggest potential problems with storing or contamination within all measurement flights. Two last flights # 130-133 and # 166-169 comply with the tests therefore their detailed analysis is made. Samples were analyzed in terms of their origin (troposphere vs. stratosphere, backward trajectories), their aging (NMHCs ratios) and detected plumes were compared to chemical signatures of Asian outflows. In the last chapter a future development of the presented system with focus on separation is drawn. An extensive appendix documents all important aspects of the dissertation from theoretical introduction through illustration of sample treatment to overview diagrams for the measured flights.

I manoscritti miniati dell'Illustratore nella cultura figurativa del secondo quarto del XIV secolo

La tesi è dedicata alla personalità artistica dell’Illustratore, tra i protagonisti della miniatura bolognese degli anni trenta e quaranta del Trecento, così felicemente soprannominato da Roberto Longhi. Dopo un capitolo dedicato alla vicenda critica dell’artista, la tesi affronta il percorso artistico dell’Illustratore nell’ambito della decorazione libraria bolognese del secondo quarto del XIV secolo. Ho trattato le opere attribuite al’Illustratore insieme agli esempi contemporanei della miniatura bolognese, in modo da far emergere il ruolo di questo maestro nelle relazioni con il contesto cittadino. Nella successione cronologica dei manoscritti, emerge un nuovo sconvolgimento caotico che scardina l’ordine spaziale e compositivo delle opere iniziali debitrici del giottismo del Maestro del 1328. Il capitolo si conclude con alcune osservazioni sui rapporti tra il maestro e i suoi aiuti e sul rapporto con Buffalmacco. In questo capitolo sono inoltre presentate due nuove attribuzioni. Gli ultimi due capitoli sono un approfondimento sull’interazione tra il linguaggio figurativo dell’artista e la funzione dell’immagine quale forma di comunicazione visiva in stretta relazione con i testi scritti che accompagnano e sui caratteri della committenza, là dove è possibile definirli. La prima parte del terzo capitolo è dedicata all’illustrazione dei libri legales, mentre nella seconda parte si tratta di un caso particolare, le iniziali istoriate dell’Inferno e del Purgatorio di Dante Alighieri della Biblioteca Riccardiana di Firenze (ms. 1005), per molti aspetti riconducibili all’illustrazione giuridica. La mia intenzione in questo capitolo è di verificare come il caratteristico linguaggio narrativo espressivo e diretto dell’Illustratore abbia risposto alla funzione delle immagini dipinte nei codici giuridici di offrire una struttura materiale alla memorizzazione visiva per via di luoghi e figure dei contenuti di studio del diritto comune. In appendice alla tesi si trova un catalogo dei manoscritti decorati da miniature dell’Illustratore, comprensivo anche di una sezione per le opere di dubbia o erronea attribuzione.

Tradurre la saggistica: proposta di traduzione di un estratto di "The invisible history of the human race"

The aim of this dissertation is to propose the translation of four chapters from "The invisible history of the human race", an essay by the Australian author and journalist Christine Kenneally. This essay offers a non-systematic overview upon genealogy in connection to the idea of personal identity; above all, the author wants to persuade the reader that genealogy could be the perfect linking point between history and science, family lines and DNA. The translated chapters particularly concentrate on the reasons of the current underestimation of genealogy, which, according to Kenneally, lies in the Nazi’s distorted use of ancestry and in the exploitation of the idea of biological diversity in order to discriminate people. The dissertation is composed of four chapters. The first chapter consists in a concise analysis of the characteristics of the textual genre and in a theoretical introduction and approach to the translation of essays, where the main generic and essay-specific translation strategies are outlined. The second chapter presents a detailed illustration of the topics treated in the essay and particularly in the translated pages. The third chapter contains the translation and the fourth presents a systematic comment to the translation and to the choices made during the translation of the text.

Experimental Evaluation of Immediate Recanalization Effect and Recanalization Efficacy of a New Thrombus Retriever for Acute Stroke Treatment In Vivo

BACKGROUND AND PURPOSE: Currently, several new stent retriever devices for acute stroke treatment are under development and early clinical evaluation. Preclinical testing under standardized conditions is an important first step to evaluate the technical performance and potential of these devices. The aim of this study was to evaluate the immediate recanalization effect, recanalization efficacy, thrombus-device interaction, and safety of a new stent retriever intended for thrombectomy in patients with acute stroke. MATERIAL AND METHODS: The pREset thrombectomy device (4 × 20 mm) was evaluated in 16 vessel occlusions in an established swine model. Radiopaque thrombi (10-mm length) were used for visualization of thrombus-device interaction during application and retrieval. Flow-restoration effect immediately after deployment and after 5-minute embedding time before retrieval, recanalization rate after retrieval, thromboembolic events, and complications were assessed. High-resolution FPCT was performed to illustrate thrombus-device interaction during the embedding time. RESULTS: Immediate flow restoration was achieved in 75% of occlusions. An increase or stable percentage of recanalizations during embedding time before retrieval was seen in 56.3%; a decrease, in 12.5%; reocclusion of a previously recanalized vessel, in 18.8%; and no recanalization effect at all, in 12.5%. Complete recanalization (TICI 3) after retrieval was achieved in 93.8%; partial recanalization (TICI 2b), in 6.2%. No distal thromboembolic events were observed. High-resolution FPCT illustrated entrapment of the thrombus between the stent struts and compression against the contralateral vessel wall, leading to partial flow restoration. During retrieval, the thrombus was retained in a straight position within the stent struts. CONCLUSIONS: In this experimental study, the pREset thrombus retriever showed a high recanalization rate in vivo. High-resolution FPCT allows detailed illustration of the thrombus-device interaction during embedding time and is advocated as an add-on tool to the animal model used in this study.

Limitations of the Odds Ratio in Gauging the Performance of a Diagnostic or Prognostic Marker

A marker that is strongly associated with outcome (or disease) is often assumed to be effective for classifying individuals according to their current or future outcome. However, for this to be true, the associated odds ratio must be of a magnitude rarely seen in epidemiological studies. An illustration of the relationship between odds ratios and receiver operating characteristic (ROC) curves shows, for example, that a marker with an odds ratio as high as 3 is in fact a very poor classification tool. If a marker identifies 10 percent of controls as positive (false positives) and has an odds ratio of 3, then it will only correctly identify 25 percent of cases as positive (true positives). Moreover, the authors illustrate that a single measure of association such as an odds ratio does not meaningfully describe a marker’s ability to classify subjects. Appropriate statistical methods for assessing and reporting the classification power of a marker are described. The serious pitfalls of using more traditional methods based on parameters in logistic regression models are illustrated.

Nonparametric Estimation of the Bivariate Recurrence Time Distribution

This paper considers statistical models in which two different types of events, such as the diagnosis of a disease and the remission of the disease, occur alternately over time and are observed subject to right censoring. We propose nonparametric estimators for the joint distribution of bivariate recurrence times and the marginal distribution of the first recurrence time. In general, the marginal distribution of the second recurrence time cannot be estimated due to an identifiability problem, but a conditional distribution of the second recurrence time can be estimated non-parametrically. In literature, statistical methods have been developed to estimate the joint distribution of bivariate recurrence times based on data of the first pair of censored bivariate recurrence times. These methods are efficient in the current model because recurrence times of higher orders are not used. Asymptotic properties of the estimators are established. Numerical studies demonstrate the estimator performs well with practical sample sizes. We apply the proposed method to a Denmark psychiatric case register data set for illustration of the methods and theory.

Alternative splicing of pre-mRNA in cancer: focus on G protein-coupled peptide hormone receptors

Through alternative splicing, multiple different transcripts can be generated from a single gene. Alternative splicing represents an important molecular mechanism of gene regulation in physiological processes such as developmental programming as well as in disease. In cancer, splicing is significantly altered. Tumors express a different collection of alternative spliceoforms than normal tissues. Many tumor-associated splice variants arise from genes with an established role in carcinogenesis or tumor progression, and their functions can be oncogenic. This raises the possibility that products of alternative splicing play a pathogenic role in cancer. Moreover, cancer-associated spliceoforms represent potential diagnostic biomarkers and therapeutic targets. G protein-coupled peptide hormone receptors provide a good illustration of alternative splicing in cancer. The wild-type forms of these receptors have long been known to be expressed in cancer and to modulate tumor cell functions. They are also recognized as attractive clinical targets. Recently, splice variants of these receptors have been increasingly identified in various types of cancer. In particular, alternative cholecystokinin type 2, secretin, and growth hormone-releasing hormone receptor spliceoforms are expressed in tumors. Peptide hormone receptor splice variants can fundamentally differ from their wild-type receptor counterparts in pharmacological and functional characteristics, in their distribution in normal and malignant tissues, and in their potential use for clinical applications.

On the Limits of Greenwich Mean Time, or The Failure of a Modernist Revolution

On the Limits of Greenwich Mean Time, or The Failure of a Modernist Revolution From the introduction of World Standard Time in 1884 to Einstein’s theory of relativity, the nature and regulation of time was a highly contested issue in modernism, with profound political, social and epistemological consequences. Modernist aesthetic sensibilities widely revolted against the increasingly strict rule of the clock, which, as Georg Simmel observed in “The Metropolis and Mental Life,” was established as the necessary basis of a capitalist, urban life. This paper will focus on the contending conceptions of time arising in key modernist texts by authors like Joyce, Woolf and Conrad. I will argue that the uniformity and regularity of time necessary to a rising capitalist society came under attack in a similar way by both modernist literary aesthetics and new scientific discoveries. However, while Einstein’s theory of relativity may have led to a subsequent change of paradigm in scientific thought, it has failed to significantly alter social and popular conceptions of time. Although alternative ways of thinking and living with time are proposed by modernist authors, they remain isolated aesthetic experiments, ineffectual against the regulatory pressure of economic and social structures. In this struggle about the nature of time, so I suggest, science and literature join force against a society that is increasingly governed by economic reason. The fact that they lost this struggle can serve as a striking illustration of an increasing shift of social influence from science and art towards economy.

Three-dimensional printing for perioperative planning of complex aortic arch surgery

Purpose In this study, we show the use of three-dimensional printing models for preoperative planning of surgery for patients with complex aortic arch anomalies. Description A 70-year-old man with an extensively arteriosclerotic aneurysm reaching from the ascending aorta to the descending aorta was referred to our center for complete aortic arch replacement. We visualized and reconstructed computed tomography data of the patient and fabricated a flexible three-dimensional model of the aortic arch including the aneurysm. Evaluation This model was very helpful for the preoperative decision making and planning of the frozen elephant trunk procedure owing to the exact and lifelike illustration of the native aortic arch. Conclusions Three-dimensional models are helpful in preoperative planning and postoperative evaluation of frozen elephant trunk procedures in patients with complex aortic anatomy.

Capital interplays and the self-rated health of young men: results from a cross-sectional study in Switzerland.

INTRODUCTION We apply capital interplay theory to health inequalities in Switzerland by investigating the interconnected effects of parental cultural, economic and social capitals and personal educational stream on the self-rated health of young Swiss men who live with their parents. METHODS We apply logistic regression modelling to self-rated health in original cross-sectional survey data collected during mandatory conscription of Swiss male citizens in 2010 and 2011 (n = 23,975). RESULTS In comparison with sons whose parents completed mandatory schooling only, sons with parents who completed technical college or university were significantly more likely to report very good or excellent self-rated health. Parental economic capital was an important mediating factor in this regard. Number of books in the home (parental cultural capital), family economic circumstances (parental economic capital) and parental ties to influential people (parental social capital) were also independently associated with the self-rated health of the sons. Although sons in the highest educational stream tended to report better health than those in the lowest, we found little evidence for a health-producing intergenerational transmission of capitals via the education stream of the sons. Finally, the positive association between personal education and self-rated health was stronger among sons with relatively poorly educated parents and stronger among sons with parents who were relatively low in social capital. CONCLUSIONS Our study provides empirical support for the role of capital interplays, social processes in which capitals interpenetrate or co-constitute one another, in the intergenerational production of the health of young men in Switzerland.

How gender fair are German schoolbooks in the twenty-first century? An analysis of language and illustrations in schoolbooks for mathematics and German

Schoolbooks convey not only school-relevant knowledge; they also influence the development of stereotypes about different social groups. Particularly during the 1970s and 1980s, many studies analysed schoolbooks and criticised the overall predominance of male persons and of traditional role allocations. Since that time, women’s and men’s occupations and social functions have changed considerably. The present research investigated gender portrayals in schoolbooks for German and mathematics that were recently published in Germany. We examined the proportions of female and male persons in pictures and texts and categorized their activities, occupational and parental roles. Going beyond previous studies, we added two criteria: the use of gender-fair language and the spatial arrangements of persons in pictures. Our results show that schoolbooks for German contained almost balanced depictions of girls and boys, whereas women were less frequently shown than men. In mathematics books, males outnumbered females in general. Across both types of books, female and male persons were engaged in many different activities, not only gendertyped ones; however, male persons were more often described via their profession than females. Use of gender-fair language has found its way into schoolbooks but is not used consistently. Books for German were more gender fair in terms of linguistic forms than books for mathematics. For spatial arrangements, we found no indication for gender biases. The results are discussed with a focus on how schoolbooks can be optimized to contribute to gender equality.