Academic literature on the topic 'Copule mixte'

AbstractParasites play a central role in the adaptiveness of sexual reproduction. Sexual selection theory suggests a role for parasite resistance in the context of mate choice, but the evidence is mixed. The parasite-mediated sexual selection (PMSS) hypothesis derives a number of predictions, among which that resistance to parasites is heritable, and that female choice favors parasite resistance genes in males. Here, we tested the PMSS hypothesis using the dung beetle Onthophagus taurus, a species that can be heavily parasitized by Macrocheles merdarius mites, which are known to affect adult survival. We investigated the heritability of resistance to M. merdarius, as well as whether female O. taurus impose a mating bias against males susceptible to mite infestation. Female choice for parasite resistance is difficult to disentangle from the possibility that females are simply choosing less parasitized males due to naturally selected benefits of avoiding contracting those parasites. This is especially likely for ectoparasites, such as mites. We tackled this problem by performing a mate choice trial first, and then measuring a male’s resistance to mite infestation. Resistance to mite infestation exhibited significant levels of additive genetic variance. Although we found no relationship between mating success and parasite resistance, males with greater resistance to infestation mated for longer. If females control copula duration, given that short copulations often result in mating failure, female choice could act on parasite resistance.

- Cross-cultural couples are one of the most important indica-tor of integration between natives and immigrants living within the same territory. This is an emergent phenomenon today in Italy.Using the data of some researches conducted by the author from 2003 to 2008, this article sketches out the profiles and the family life of cross-cultural couples formed by an Italian wife/husband and an immigrant partner: the first encounter, the beginnings of the relationship, the decision to live together and to marry, the family's and friends' reactions, the differences that create problems and/or opportunities in the private life.Keywords Cross-cultural couples, mixed marriages, migra-tion, family

Considerando el carácter cada vez más multicultural de nuestras sociedades, las parejas mixtas son una de los más relevantes indicadores de la integración de los inmigrantes en los países de destino, al tiempo que representan escenarios de encuentro y desencuentro de diferencias de toda índole (cultural, étnica, lingüística, religiosa, política, de clase, de ingresos, de nivel cultural, etc.). En este contexto se sitúa el presente artículo en el cual se estudia esta dinámica a partir de los discursos de parejas mixtas en Italia.

Les observations du comportement des investisseurs sur les marchés financiers suggèrent que les investisseurs sont de plus en plus sensibles aux critères extra-financiers dans le processus de construction des portefeuilles. Nous menons donc 2 études empiriques sur l’impact de l’adoption d’une stratégie d’investissement intégrant les enjeux environnementaux, sociaux et de gouvernance dans la sélection d’actifs (ESG) sur la performance des portefeuilles. La première étude nous a permis de comparer la performance de trois portefeuilles composés d’actions du marché américain. La composition de ces portefeuilles a été faite via des filtres ESG. D’une part les best-in-class c’est-à-dire les actions ayant les meilleures notations ESG, puis celles avec les notations moyennes et pour finir les actions les moins bien notées. La mise en œuvre de l’optimisation s’effectue dans un cadre théorique mean-LPM qui met en évidence notre modélisation spécifique de la structure de dépendance du portefeuille. La deuxième étude porte cette fois sur deux portefeuilles constitués d’actions du marché de la zone euro. Un portefeuille avec les best-in-class et le second composé d’actions ayant des notations homogènes. À la différence de la première étude, l’optimisation est faite dans un cadre théorique worst case worst case mixture copula mean-CvaR. De ces études nous sommes arrivés à la conclusion que ce critère n’est pas incompatible avec le profit mais il faudrait réduire ces exigences en terme de préférence pour les actions avec les notes ESG élevées. En vue d’une potentielle extension avec des modèles plus performants,une troisième étude empirique a été réalisée pour mettre en évidence la puissance et la pertinence des modèles d’apprentissage automatique pour la prévision de séries temporelles financières. Ou comme alternative une hybridation entre modèle de réseaux de neurones artificiels et le modèle ARIMA pour prédire la tendance de la série temporelle
Observations of investor behavior in financial markets suggest that investors are increasingly sensitive to non-financial criteria in the portfolio construction process. We therefore conduct two empirical studies on the impact of adopting an investment strategy that integrates environmental, social and governance (ESG) issues into asset selection on portfolio performance. The first study allowed us to compare the performance of three portfolios composed of U.S. market stocks. The composition of these portfolios was made via ESG filters. First, the best-in-class stocks, i.e. those with the highest ESG ratings, then those with average ratings and finally the lowest rated stocks and finally the lowest rated stocks. The implementation of the optimization is carried out in a mean-LPM theoretical framework that highlights our specific modeling of the portfolio dependency structure. The second study focuses on two portfolios of Eurozone stocks. One portfolio withthe best-in-class and the second one composed of stocks with homogeneous ratings. Unlike the first study, theoptimization is done in a worst case worst case mixture copula mean-CvaR theoretical framework. From these studies we concluded that this criterion is not incompatible with profit, but it would be necessary to reduce these requirements in terms of preference for stocks with high ESG ratings. In view of a potential extension with more efficient models, a third empirical study was conducted to highlight the power and relevance of machine learning models for forecasting financial time series. Or as an alternative a hybridization between artificial neural network model and ARIMA model to predict the trend of the time series

VERRA' ANALIZZATA LA PRESENZA DI COPPIE MISTE IN ITALIA, E PARTENDO DALLA RIFLESSIONE SUI PRINCIPI TEORICI DEL SERVIZIO SOCIALE, SI CERCHERANNO LE BUONE PRASSI CHE FACILITINO L'INTERVENTO DA PARTE DE PROFESSIONISTA.

Cette thèse propose une contribution originale pour la classification non supervisée de données qualitatives ou de données mixtes. Les approches proposées sont à base de modèles probabilistes ayant pour but de modéliser la distribution des données observées. Dans les cas de données qualitatives ou mixtes, il est d'usage de supposer l'indépendance entre les variables conditionnellement à la classe. Cependant, cette approche s'avère biaisée lorsque l'hypothèse d'indépendance conditionnelle est erronée. L'objet de cette thèse est d'étudier et de proposer des modèles relâchant l'hypothèse d'indépendance conditionnelle. Ceux-ci doivent permettre de résumer chaque classe par quelques paramètres significatifs. La première partie de cette thèse porte sur la classification non supervisée de données qualitatives. Lorsque ces données sont corrélées au sein des classes, le statisticien est confronté à de nombreux problèmes combinatoires (grand nombre de paramètres et choix de modèle complexe). Notre approche consiste à relâcher l'hypothèse d'indépendance conditionnelle en regroupant les variables en blocs conditionnellement indépendants. Cette méthode nous amène à présenter deux modèles probabilistes. Ceux-ci définissent la distribution d'un bloc de manière à limiter le nombre de paramètres du modèle tout en fournissant un modèle facilement interprétable. Le premier modélise la distribution d'un bloc de variables par le mélange des deux distributions de dépendances extrêmes tandis que le second modèle utilise une distribution multinomiale par modes. La seconde partie de cette thèse porte sur la classification non supervisée de données mixtes. La difficulté spécifique à de telle données est due à l'absence de distribution de référence pour le cas de variables de différentes natures. Ainsi, on souhaite définir un modèle probabiliste respectant les deux contraintes suivantes. Tout d'abord, les distributions marginales de chacune des composantes doivent être des distributions classiques afin de faciliter l'interprétation du modèle. De plus, le modèle doit permettre de caractériser les dépendances intra-classes par quelques paramètres significatifs. Ce cahier des charges nous amène naturellement à utiliser la théorie des copules. Ainsi, nous proposons un modèle de mélange de copules gaussiennes que nous considérons comme la contribution majeure de cette thèse. Pour ce modèle, nous effectuons une inférence bayésienne à partir d'un échantillonneur de Gibbs. Les critères d'information classiques (BIC, ICL), nous permettent de répondre aux problématiques de choix de modèles
This work is our contribution to the cluster analysis of categorical and mixed data. The methods proposed in this manuscript modelize the data distribution in a probabilistic framework. When the data are categorical or mixed, the classical model assumes the independence between the variables conditionally on class. However, this approach is biased when the variables are intra-class correlated. The aim of this thesis is to study and to present some mixture models which relax the conditional independence assumption. Moreover, they have to summarize each class with few characteristic parameters. The first part of this manuscript is devoted to the cluster analysis of categorical data. The categorical variables are difficult to cluster since they leave the statistician facing with many combinatorial challenges. In this context, our contribution consists in two parsimonious mixture models which allow to cluster categorical data presenting intra-class dependencies. The main idea of these models is to group the variables into conditionally independent blocks. By setting specific distributions for these blocks, both models consider the intra-classdependencies between the variables. The first approach modelizes the block distribution by a mixture of two extreme dependency distributions while the second approach modelizes it by a multinomial distribution per modes. The study of the cluster analysis of mixed data sets is the second objective of this work. The challenge is due to the lack of classical distributions for mixed variables. Thus, we defined a probabilistic model respecting two main constraints. Firstly, the one-dimensional margin distributions of the components are classical for each variables. Secondly, the model characterizes the main intra-class dependencies. This model is defined as a mixture of Gaussian copulas. The Bayesian inference is performed via a Gibbs sampler. The classical information criteria (BIC, ICL) permit to perform the model selection

Abstract Nowadays, the concepts of difference, identity and culture structure the discourse on the complexity of contemporary societies. Most of the debates concerns political actions and conflicts seem now to address the issue of protection, claim or recognition of difference (Colombo & Semi, 2007). Mixed couples are, at the same time, both index and agent of change (Gritti, 2004). They are closely related to the increase of migration flows and provide us with a closer perspective to analyse the processes of growing pluralism in our society. This study is focused on the processes of mixité conjugale in the life stories of 15 mixed couples characterized by male migrants from countries with Muslim tradition married to Italian women. These couples embody, indeed, an emblematic case study within the phenomenon of "mixed" couples, since they led to their implicit macro dimension which links to cultural, religious, gender and class differences, represented as "strong differences" in the public debate (Saraceno, 2007). The participant observation and the discursive representations result from more than 50 meetings with 15 families residing in various areas of the Veneto Region. Individual interviews were conducted with both partners, sometimes with their children, but also with witnesses such as relatives or friends of the couple. The core of my fieldwork is represented by the partners’ recits de vie (Bertaux, 1981) through which I focused on how these couples built alliances in their everyday interaction, then in the comparison of cultural, family and parenting models, that are the beating heart and the specificity of each mixité. The PhD thesis follows the coordinates that these life stories trace, thus reconstructing the geography of their mixité. The emphasis is initially located on the osmotic connection between “inside” and “outside”, which represents the symbolic space where the couple is placed. These narratives prove to be valuable indicators to reveal the reactions that the union raises in their respective groups. This interdependence between internal and external highlights the mechanisms of inclusion and exclusion which are triggered by the formation of the couple. Starting from a more general overview on what makes mixité a cultural construction linked to the perception of the “difference” in a given social context, our reflection moves, therefore, into the processes of mixité conjugale. Thus, we enter the everyday life dimension of their narratives, where partners recount their choices, fragmented by that complex of practices which produces a shared couple’s dimension. These narratives show us partners’ experience in living difference, discussing and rewriting cultural boundaries. To analyse how partners build their own "practical knowledge" in the everyday life dimension (Gouldner, 1975; Colombo & Semi, 2007) means to provide polyphony to those cultural processes often reified and reduced to monolithic and unchanging containers. To interpret and to live pluralism in daily practices reveal a continuous synergy between partners and between them and their cultural backgrounds. Looking at the cultural boundaries implies to illuminate the symbolic space occupied by the alter in the couple. Differences become a resource which is at the same time claimed, overcome, denied or modified by the partners. Love on the background is the “communication code” (Luhmann, 1982) which conveys and solves the sense of complexity – as it is managed by the couple - through its capability to live the difference in the daily dimension. Love which challenges the boundaries of what is legitimate and pure (Douglas, 1970), sometimes rewriting them, writing its proper way to “be a couple”, “to make family”, “to make home away from home”.
Abstract Differenza, identità e cultura risultano oggi concetti che costruiscono l’asse su cui si incardina il macro discorso relativo alla complessità delle nostre società contemporanee. Gran parte dei dibattiti, delle preoccupazioni, delle azioni politiche e dei conflitti sembrano ruotare oggi intorno al tema della difesa, della rivendicazione o del riconoscimento della differenza (Colombo&Semi, 2007). Le coppie miste insieme come indice e fattore di cambiamento (Gritti, 2004) strettamente correlato all’aumento dei flussi migratori ci offrono una prospettiva ravvicinata per studiare i processi che sottintendono il crescente pluralismo delle nostre società. La presente ricerca si basa su uno studio etnografico volto ad indagare i processi di mixité coniugale nei racconti di vita di 15 coppie miste caratterizzate da uomini migranti provenienti da Paesi di tradizione musulmana sposati con donne italiane. Queste coppie rappresentano, infatti, un caso di studio emblematico all’interno del fenomeno delle coppie “miste” proprio perché riconducono ad una loro implicita dimensione macro che mette l’una accanto all’altra, nello spazio sociale della famiglia, differenze culturali, religiose, di genere e di classe rappresentate come “differenze forti” nel dibattito pubblico (Saraceno, 2007). L’osservazione partecipante e le rappresentazioni discorsive raccolte nascono da più di 50 incontri con 15 famiglie residenti in varie località del Veneto. Nelle loro case sono state svolte interviste individuali ai partner, talvolta ai figli, ma anche ai testimoni privilegiati quali parenti o conoscenti della coppia. Al centro del mio lavoro sul campo vi sono i racconti di vita (Bertaux, 1981) dei partner, per focalizzarmi sull’analisi di come vengano costruite alleanze proprio nell’interazione quotidiana e ravvicinata con l’alter, quindi nel confronto tra modelli culturali, familiari e genitoriali che costituiscono poi il cuore pulsante e la specificità di ogni mixité coniugale. La tesi segue le coordinate che questi racconti di vita tracciano, ricostruendo così la geografia della loro mixité. L’accento è inizialmente posto sulla connessione osmotica tra interno ed esterno che è lo spazio simbolico entro cui la coppia si rappresenta. Queste narrazioni risultano essere dei preziosi indicatori per portare alla luce quel complesso sistema di reazioni e relazioni che l’unione solleva nei rispettivi gruppi di riferimento. Proprio questa dinamica di interdipendenza tra interno ed esterno mette in evidenza i meccanismi di inclusione ed esclusione che si innescano intorno al formarsi della coppia. Da ciò che fa della mixité una costruzione culturale legata proprio alla percezione della differenza in un dato contesto passiamo, dunque, all’interno dei processi di mixité coniugale. Volgiamo così lo sguardo alla dimensione quotidiana del racconto di vita, dove i partner narrano la scelta frammentata in quell’insieme complesso e sfaccettato di prassi costruito ed elaborato dai partner per creare una dimensione condivisa di coppia. Esso diventa così un racconto che coinvolge i partner: la loro esperienza nel vivere la differenza, nel mischiare le culture tracciandone, negoziandone e riscrivendone i confini. Analizzare come i partner costruiscano il proprio “sapere pratico” nella dimensione quotidiana (Gouldner, 1975; Colombo&Semi, 2007) permette di dare polifonia a quei processi culturali spesso reificati ed essenzializzati come contenitori monolitici ed immutabili. La varietà dei modi di interpretare e vivere il pluralismo nel racconto delle pratiche quotidiane ci parla, così, di come vi sia una continua sinergia tra i partner e tra questi e le reti che li legano al contesto sociale italiano e a quello di origine del partner straniero.

La tesi è dedicata al fenomeno delle coppie miste, all'epoca emergente in italia, e pochissimo esplorato dalla letteratura sociologica nazionale. La ricerca è condotta contemporaneamente su due piani: teorico ed empirico. La prima parte è una disamina accurata sul significato che i concetti di mixité e coppia mista assumono nella società eterogenee e frammentate di oggi. Nella seconda parte, dapprima un'indagine statistica condotta sulla base dei dati forniti da tre anagrafi comunali toscane illustra le dinamiche di interazione matrimoniale dei diversi gruppi nazionali residenti sul territorio; a seguire, un viaggio di esplorazione con strategie qualitative penetra all'interno dei contesti coniugali di diverse coppie, per indagare i meccanismi della comunicazione e del conflitto interculturale. 1/11/2004, Firenze. Conseguimento del Dottorato di Ricerca in “Sociologia della Comunicazione” (durata triennale) dell’’Università degli Studi di Firenze. Commissione giudicatrice: prof. Giovanni Bechelloni (Università di Firenze), prof. Anna Lucia Natale (Università del Molise), prof. Luciano Benadusi (Università di Roma La Sapienza). Titolo della dissertazione finale: Unioni non comuni. I percorsi di integrazione delle coppie miste in Toscana. Giudizio finale conseguito: “Le ricerche oggetto della tesi sono originali e basate su statistiche sociali ed interviste qualitative. Le metodologie appaiono corrette rispetto agli scopi della ricerca difficile e complessa. I risultati sono interessanti ed analizzati con senso critico e degni di essere pubblicati. Nel colloquio la candidata dimostra conoscenza delle problematiche trattate con proprietà di lessico e forza argomentativa”.