Symmetric Synchronous Collaborative Navigation

Synchronous collaborative navigation is a form of social navigation where users virtually share a web browser. In this paper, we present a symmetric, proxy-based architecture where each user can take the lead and guide others in visiting web sites, without the need for a special browser or other software. We show how we have applied this scheme to a problem-solving-oriented e-learning system

A class of random walks in reversible dynamic environment: antisymmetry and applications to the East model

We introduce via perturbation a class of random walks in reversible dynamic environments having a spectral gap. In this setting one can apply the mathematical results derived in http://arxiv.org/abs/1602.06322. As first results, we show that the asymptotic velocity is antisymmetric in the perturbative parameter and, for a subclass of random walks, we characterize the velocity and a stationary distribution of the environment seen from the walker as suitable series in the perturbative parameter. We then consider as a special case a random walk on the East model that tends to follow dynamical interfaces between empty and occupied regions. We study the asymptotic velocity and density profile for the environment seen from the walker. In particular, we determine the sign of the velocity when the density of the underlying East process is not 1/2, and we discuss the appearance of a drift in the balanced setting given by density 1/2

On the dimension of contact loci and the identifiability of tensors

Let $X\subset \mathbb{P}^r$ be an integral and non-degenerate variety. Set $n:= \dim (X)$. We prove that if the $(k+n-1)$-secant variety of $X$ has (the expected) dimension $(k+n-1)(n+1)-1<r$ and $X$ is not uniruled by lines, then $X$ is not $k$-weakly defective and hence the $k$-secant variety satisfies identifiability, i.e. a general element of it is in the linear span of a unique $S\subset X$ with $\sharp (S) =k$. We apply this result to many Segre-Veronese varieties and to the identifiability of Gaussian mixtures $G_{1,d}$. If $X$ is the Segre embedding of a multiprojective space we prove identifiability for the $k$-secant variety (assuming that the $(k+n-1)$-secant variety has dimension $(k+n-1)(n+1)-1<r$, this is a known result in many cases), beating several bounds on the identifiability of tensors.Comment: 12 page

Strong convergence of solutions to nonautonomous Kolmogorov equations

We study a class of nonautonomous, linear, parabolic equations with unbounded coefficients on $\mathbb R^{d}$ which admit an evolution system of measures. It is shown that the solutions of these equations converge to constant functions as $t\to+\infty$. We further establish the uniqueness of the tight evolution system of measures and treat the case of converging coefficients

Ingroup/outgroup dynamics and agency markers in Italian parliamentary language. A gender-based socio-psychological analysis of the speeches of men and women deputies (2001 and 2006).

The most recent literature on gender differences in language use has shown that the Italian political communication enacted by men and women parliamentarians only partly reflects and reproduces the asymmetries and stereotypes widespread in society. Starting from an anti-essentialist perspective, which holds that language differences between men and women speakers are much less extensive than claimed in the past, we analysed 463 parliamentary speeches in the course of the XIVth legislature (5-2001 / 4-2006) in four parliamentarian pairs, differentiated by gender and political orientation. The general aim was to explore the socio-psychological constructs of agency and ingroup/outgroup dynamics as revealed by linguistic behaviour in men/women parliamentarians. The two constructs were detected by specific linguistic markers in the interventions of men/women parliamentarian pairs. Specifically, for agency, we detected: (1a) pronoun variations between singular and plural first person (I, we); (1b) amplitude of we as either specific or superordinate; (1c) conditional modal form of verbs. For ingroup/outgroup dynamics, we detected: (2a) pronoun variation between first and second plural person (we vs. you) and (2b) their valence. Lexicographical analysis was carried out with statistical packages TaLTaC2 and TreeTagger on a corpus of 432,671 words. Chi-square and z-test were applied to word frequencies, while Student’s t-tests were applied to gender comparisons. The results showed reduced variability between men/women parliamentarians in the use of linguistic devices, confirming the weakness of the essentialist and binary logic that has long dominated the field of studies on language and gender

La Dolce Vita: Hedonic Estimates of Quality of Life in Italian Cities

This paper provides an assessment of quality of life in Italian cities using the hedonic approach. We analyze micro-level data for housing and labor markets to estimate compensating differentials for local amenities within five domains: climate, environment, services, society and economy. The estimated implicit prices are used to construct overall and domain-specific quality of life indices. We find that differences in amenities are reflected in substantial compensating differentials in housing prices, whereas the effects on wages are relatively small. Quality of life varies substantially across space and is strongly related to differences in public services and economic conditions. Overall, quality of life is highest in medium-sized cities of the Center-North, displaying relatively high scores in all the domains considered. Northern cities fare better with respect to services, social and economic conditions, while relatively worse for climate and environmental conditions.quality of life, hedonic prices, housing markets

Intergenerational Transmission of Skills during Childhood and Optimal Public Policy

The paper characterizes the optimal tax policy and the optimal quality of day care services in a OLG model with warm-glow altruism where parental choices over child care arrangements affect the probability that the child becomes a high-skilled adult in a type-specific way. With respect to previous contributions, optimal tax formulas include type-specific Pigouvian terms which correct for the intergenerational externality in human capital accumulation. Our numerical simulations suggest that a public policy that disregards the effects of parental time on children's human capital entails a welfare loss that ranges from 0:2% to 5:7% of aggregate consumption.optimal taxation, day care quality, intergenerational transmission of skills, early childhood environment, warm-glow

Intergenerational transmission of skills during childhood and optimal public policy

The paper characterizes the optimal tax policy and the optimal quality of day care services in a OLG model with warm-glow altruism where parental choices over child care arrangements affect the probability that the child becomes a high-skilled adult in a type-specific way. With respect to previous contributions, optimal tax formulas include type-specific Pigouvian terms which correct for the intergenerational externality in human capital accumulation. Our numerical simulations suggest that a public policy that disregards the effects of parental time on children's human capital entails a welfare loss that ranges from 0:2% to 5:7% of aggregate consumption.optimal taxation; day care quality; intergenerational transmission of skills; early childhood environment; warm-glow

Bounds on the tensor rank

We give a sufficient criterion for a lower bound of the cactus rank of a tensor. Then we refine that criterion in order to be able to give an explicit sufficient condition for a non-redundant decomposition of a tensor to be minimal and unique.Comment: 14 page