Search results for " Models"
showing 10 items of 4240 documents
Resident’s Perceptions of Tourism Influence on Quality of Life: a Multilevel approach.
2015
This study aims to evaluate whether individual perceptions of tourism’s effects on quality of life (TQOL) are related to the degree of tourism activity in the host community, as well as to residents’ personal characteristics, by a multilevel model. Data from a survey performed in Sicily have been analyzed. The model revealed that the level of tourism activity have an influence on the way residents perceive the effect tourism in their community, as measured by TOQL index.
The Emergence of Women as Main Earners in Europe
2014
This paper conducts a cross-sectional empirical research aimed at documenting the emergence of a new family model characterized by women who earn the largest share of their household income. We show that in Europe, couples with women as the main earner have started to represent a non-negligible share of the population and identify the key characteristics of couples in which women are the main earner in comparison to equal-earner couples and to couples in which men are the main earner. We undertake a comparative approach using micro-level data from the European Social Survey on 19 countries and two time periods (2004 and 2010).
Discrete Time Portfolio Selection with Lévy Processes
2007
This paper analyzes discrete time portfolio selection models with Lévy processes. We first implement portfolio models under the hypotheses the vector of log-returns follow or a multivariate Variance Gamma model or a Multivariate Normal Inverse Gaussian model or a Brownian Motion. In particular, we propose an ex-ante and an ex-post empirical comparisons by the point of view of different investors. Thus, we compare portfolio strategies considering different term structure scenarios and different distributional assumptions when unlimited short sales are allowed.
Statistically Validated Networks for evaluating coherence in topic models
2022
Probabilistic topic models have become one of the most widespread machine learning technique for textual analysis purpose. In this framework, Latent Dirichlet Allocation (LDA) gained more and more popularity as a text modelling technique. The idea is that documents are represented as random mixtures over latent topics, where a distribution over words characterizes each topic. Unfortunately, topic models do not guarantee the interpretability of their outputs. The topics learned from the model may be characterized by a set of irrelevant or unchained words, being useless for the interpretation. In the framework of topic quality evaluation, the pairwise semantic cohesion among the top-N most pr…
Marked Hawkes processes for Twitter data
2022
In this paper, we propose to model retweet event sequences using a marked Hawkes process, which is a self-exciting point process where the occurrence of previous events in time increases the probability of further events. The aim is to analyse Twitter data combining temporal point processes theory and textual analysis. Since each retweet event carries a set of properties, we mark the process by different characteristics drawn from the textual analysis, finding that the tone of the description of the Twitter user is a good predictor of the number of retweets in a single cascade.
Jessie Bernard. Paradossi dei matrimoni felici e della maternità incondizionata
2022
Questo volume introduce per la prima volta in Italia il pensiero di Jessie Bernard, la cui produzione scientifica sui temi del genere e del femminile – dal matrimonio alla maternità, dalla segregazione alla mobilità professionale – ha fornito un importante contribuito alla rivoluzione femminista, proponendo un’analisi articolata del “sistema coniugale americano” e dei condizionamenti operanti sulle famiglie bianche e su quelle di colore in tema di maternità. Il pensiero di Jessie Bernard non si situa in una lotta ideologica, ma nell’esperienza di una studiosa che ha “scalato le montagne” dell’irrisione coniugale, della sufficienza accademica e del sospetto femminista. Una riflessività – que…
THE EFFECT OF ALTERNATIVE PREY ON THE DYNAMICS OF IMPERFECT BATESIAN AND MÜLLERIAN MIMICRIES
2004
Both Batesian and Müllerian mimicries are considered classical evidence of natural selection where predation pressure has, at times, created a striking similarity between unrelated prey species. Batesian mimicry, in which palatable mimics resemble unpalatable aposematic species, is parasitic and only beneficial to the mimics. By contrast, in classical Müllerian mimicry the cost of predators' avoidance learning is shared between similar unpalatable co-mimics, and therefore mimicry benefits all parties. Recent studies using mathematical modeling have questioned the dynamics of Müllerian mimicry, suggesting that fitness benefits should be calculated in a way similar to Batesian mimicry; that i…
MAST solution of irrotational flow problems in 2D domains with strongly unstructured triangular meshes
2010
A new methodology for the solution of irrotational 2D flow problems in domains with strongly unstructured meshes is presented. A fractional time step procedure is applied to the original governing equations, solving consecutively a convective prediction system and a diffusive corrective system. The non linear components of the problem are concentrated in the prediction step, while the correction step leads to the solution of a linear system, of the order of the number of computational cells. A MArching in Space and Time (MAST) approach is applied for the solution of the convective prediction step. The major advantages of the model, as well as its ability to maintain the solution monotonicit…
Quantification and visualization of finite strain in 3D viscous numerical models of folding and overthrusting
2020
Abstract Finite strain analysis and three-dimensional (3D) numerical modeling are important methods to understand the deformation history of rocks. Here, we analyze finite strain in 3D numerical simulations of power-law viscous folding and overthrusting. Simulations with different and laterally varying detachment geometries cause a lateral transition from folding (for thicker detachments) to overthrusting. We compute the 3D finite strain tensor, the principal strain values and their orientations. We compute the Nadai strain, e S , and the Lode’s ratio, ν , representing the strain symmetry (constriction or flattening). We apply Hsu diagrams to visualize strain distribution in e S - ν space, …
Toward a Collective Agenda on AI for Earth Science Data Analysis
2021
In the last years we have witnessed the fields of geosciences and remote sensing and artificial intelligence to become closer. Thanks to both the massive availability of observational data, improved simulations, and algorithmic advances, these disciplines have found common objectives and challenges to advance the modeling and understanding of the Earth system. Despite such great opportunities, we also observed a worrying tendency to remain in disciplinary comfort zones applying recent advances from artificial intelligence on well resolved remote sensing problems. Here we take a position on research directions where we think the interface between these fields will have the most impact and be…