6,167 research outputs found

    Horava Gravity in the Effective Field Theory formalism: from cosmology to observational constraints

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    We consider Horava gravity within the framework of the effective field theory (EFT) of dark energy and modified gravity. We work out a complete mapping of the theory into the EFT language for an action including all the operators which are relevant for linear perturbations with up to sixth order spatial derivatives. We then employ an updated version of the EFTCAMB/EFTCosmoMC package to study the cosmology of the low-energy limit of Horava gravity and place constraints on its parameters using several cosmological data sets. In particular we use cosmic microwave background (CMB) temperature-temperature and lensing power spectra by Planck 2013, WMAP low-l polarization spectra, WiggleZ galaxy power spectrum, local Hubble measurements, Supernovae data from SNLS, SDSS and HST and the baryon acoustic oscillations measurements from BOSS, SDSS and 6dFGS. We get improved upper bounds, with respect to those from Big Bang Nucleosynthesis, on the deviation of the cosmological gravitational constant from the local Newtonian one. At the level of the background phenomenology, we find a relevant rescaling of the Hubble rate at all epoch, which has a strong impact on the cosmological observables; at the level of perturbations, we discuss in details all the relevant effects on the observables and find that in general the quasi-static approximation is not safe to describe the evolution of perturbations. Overall we find that the effects of the modifications induced by the low-energy Horava gravity action are quite dramatic and current data place tight bounds on the theory parameters.Comment: v1: 27 pages, 7 figures. v2: 28 pages, 7 figures. Changes in Figs. 2,3,4,6,7 and Tabs. 1,2. Matches published version in Phys. Dark Uni

    Migrant and native interaction : labor market and marriage market

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    The more we study the migration phenomenon the more we understand how deep rooted in its understanding is the sentence: countries of destination thought they had let in workers and they discovered instead that they had let in human beings. Much attention is paid to the economic effects of migrants in countries of destination. But relatively little attention is paid to extremely important socio-political and demographic effects. Migration and integration policies are, also, evaluated in economic terms: do migrants increase welfare costs; do they displace native workers; do they favor economic growth etc. European researchers have neglected many key aspects of family-related migration, lagging behind, in this respect, North American and Latin American research (e.g., Boyle 2002; Falicov 2007; Glick 2010). With this policy brief, we would like to point out the multiple effects that foreign workers can have in non-economic areas. In particular, we would like to point out that a policy designed to take care, for instance, of the elderly through foreign labor can have externalities on the marriage market. Hence, a correct evaluation of a policy needs to be more comprehensive and to look at all the implications of a given decision.The MPC is co-financed by the European University Institute and the European Unio

    Evaluation of railway systems: a network approach

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    Resilience and the efficiency of transportation systems are crucial for the economic development of geographical areas, and network analysis applied to railways can provide insight into the importance of branch lines and their impacts on the entire system. This paper explores the behavior of the ERC measure, a local robustness measure, on the railway network in Lombardy, Italy, and analyzes the impacts of deactivating stations or journeys on the network’s robustness. Changes in the topological properties of the network were studied by simulating potential external disturbances and analyzing the impact of deleting the most connected stations or railway lines. The numerical results show how the measures provided effectively identify critical stations and journeys within the network structure and outperform classical topological metrics. Since ERC measures take into account all of the alternative paths present in the network, they can provide valuable information for rerouting traffic along alternative paths in case of failures or disruptions. The paper’s original contribution lies in demonstrating the effectiveness of the ERC measure in identifying critical stations and journeys within the network structure

    Female migration and native marital stability : insights from Italy

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    Published online: 05 May 2016Previous research has noted that divorce rates tend to be higher when there is a surplus of marriageable women in the marriage market. This paper argues that the size and the composition of the female migrant population can affect the marital stability of natives. We tested such hypothesis taking Italy as a case-study because it exemplifies a male-breadwinner society and because it is a relatively new immigration country. We estimated discrete-time event history models predicting marital disruption on data from the nationally representative 2009 Family and Social Subjects survey. Our results illustrated that the increasing presence of first mover migrant women (coming from Central-South America and Eastern Europe) is associated with higher separation risks among natives, especially for couples with lower human capital. By advancing the relevance of foreigners as a potential driver of natives’ family life courses, our findings add to our understanding of partnership dynamics in recent immigration countries

    Sustainable lighting design through the analysis of spatial and time non-uniformities in natural lighting with the metric of the information theory

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    The indoor visual comfort of subjects faced with indoor ambient lighting varies with the position of the subject and is not constant over time. Average performance indexes, such as the mean value of Daylight Factor and Daylight Autonomy, are commonly used to analyse lighting distribution. These indexes, however, don’t properly take into account either the spatial or the time distribution of values affecting the non-uniformity of environmental lighting. Indeed, these are limited to the definition of a mean value or to the assessment of time availability of daylighting. This paper examines spatial and temporal non-uniformities in indoor lighting as possible causes of discomfort for occupants. The goal is to propose and verify possible supplementary tools to integrate traditional methods of evaluating ambient indoor lighting Use of the entropy theory with a probabilistic approach can help to obtain more detailed information about the environment. The authors have developed a case study of several sample environments and have analysed the relationships between lighting parameters and typical indices of information theory. Results show that this approach could be a useful way for predicting possible indoor visual comfort issues and for developing a preliminary assessment to a sustainable building design

    On schemes evinced by generalized additive decompositions and their regularity

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    We define and explicitly construct schemes evinced by generalized additive decompositions (GADs) of a given dd-homogeneous polynomial FF. We employ GADs to investigate the regularity of 00-dimensional schemes apolar to FF, focusing on those satisfying some minimality conditions. We show that irredundant schemes to FF need not be dd-regular, unless they are evinced by special GADs of FF. Instead, we prove that tangential decompositions of minimal length are always dd-regular, as well as irredundant apolar schemes of length at most 2d+12d+1

    The Pro.Bio.Dic. (Prototype of a Bioethics Dictionary) project: Building a corpus of popular and specialized bioethics texts

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    This paper reports on an ongoing, long-term research project in the field of medical ethics and bioethics conducted by a multidisciplinary team combining medical, linguistic, IT and philosophical research interests: the Prototype of a Bioethics Dictionary (Pro.bio.dic). Having already outlined (Vicentini et al. 2011) the reasons and needs to both redefine and update the lexicographic material available so as to provide a corpus-based collection of the English terms of contemporary bioethics to be published on a web platform, the Pro.bio.dic has now entered the key stage of corpus-building. This stage requires establishing the criteria involved in creating a large, statistically-valid reference corpus of both specialized and popular bioethics texts, to be processed by means of text-mining and machine-learning techniques, and to serve as the basis from which the entries of the electronic online tool described as the Pro.bio.dic will be drawn by means of concordancing software
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