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showing 10 items of 2078 documents
Aggregation and sedimentation of active Brownian particles at constant affinity.
2019
We study the motility-induced phase separation of active particles driven through the interconversion of two chemical species controlled by ideal reservoirs (chemiostats). As a consequence, the propulsion speed is non-constant and depends on the actual inter-particle forces, enhancing the positive feedback between increased density and reduced motility that is responsible for the observed inhomogeneous density. For hard discs, we find that this effect is negligible and that the phase separation is controlled by the average propulsion speed. For soft particles and large propulsion speeds, however, we predict an observable impact on the collective behavior. We briefly comment on the reentrant…
Intenzionalità collettiva, ontologia sociale e mindreading
2014
In his Collective Intentions and Actions John Searle argued that having a preintentional sense of others as at least potentially cooperative agents “like me” is a necessary condition of collective intentionality. He also argued, in Rationality in Action, that understanding others qua intentional agents necessarily presupposes rationality because rational constraints are built into the logical structure of intentional phenomena. In this paper we will try to specify further these claims in the light of current debate on mindreading, where other-understanding is spelled out either in terms of automatic, subpersonal simulative mechanisms, or in terms of normative, rational principles. We will a…
Collective Intentionality, Language, and Normativity: A Problem and a Possible Solution for the Analysis of Cooperation
2015
In this paper I discuss Searle's analysis of social ontology in the light of his account of the sources of normativity as rooted in the logical structure of language. I conclude that, though his theory of normativity may appear to be inconsistent with his theory collective intentionality, it is really our Background sense of the other that creates a sense of community even before the actual functioning of collective intentionality and language, thereby escaping the dilemma between individualism and collectivism.
Recognition of familiarity on the basis of howls: a playback experiment in a captive group of wolves
2015
Playback experiments were conducted with a pack of captive Iberian wolves. We used a habituation–discrimination paradigm to test wolves’ ability to discriminate howls based on: (1) artificial manipulation of acoustic parameters of howls and (2) the identity of howling individuals. Manipulations in fundamental frequency and frequency modulation within the natural range of intra-individual howl variation did not elicit dishabituation, while manipulation of modulation pattern did produce dishabituation. With respect to identity, across trials wolves habituated to unfamiliar howls by a familiar wolf (i.e., no direct contact, but previous exposure to howls by this wolf), but not to unfamiliar ho…
Existence, uniqueness and comparison results for BSDEs with Lévy jumps in an extended monotonic generator setting
2018
We show existence of a unique solution and a comparison theorem for a one-dimensional backward stochastic differential equation with jumps that emerge from a L\'evy process. The considered generators obey a time-dependent extended monotonicity condition in the y-variable and have linear time-dependent growth. Within this setting, the results generalize those of Royer (2006), Yin and Mao (2008) and, in the $L^2$-case with linear growth, those of Kruse and Popier (2016). Moreover, we introduce an approximation technique: Given a BSDE driven by Brownian motion and Poisson random measure, we consider BSDEs where the Poisson random measure admits only jumps of size larger than $1/n$. We show con…
Counting by Statistics on Search Trees: Application to Constraint Satisfaction Problems
1997
In 1975, Knuth proposed a simple statistical method for investigating search trees. We use this technique for estimating the number of solutions of constraint satisfaction problem CSP and boolean satisfiability problem SAT instances. We show that, depending on domain reductions, tree-based estimates have a lower variance than estimates based on uniform sampling from the search space. Nevertheless, because the variance remains extremely high in the general case, a confidence interval cannot be derived, but a lower bound of the number of solutions. These results are confirmed by many experiments.
Backbone Extraction of Weighted Modular Complex Networks based on their Component Structure
2023
This work introduces a generic backbone extraction framework exploiting the mesoscopic network structure. Indeed, numerous real-world networks are made of dense groups of nodes called communities, multi-core or local components. To deal with these groups' heterogeneity, we propose to extract the backbones independently from their various components and fuse them. Experimental investigations on real-world networks demonstrate the effectiveness of the proposed approach compared to the classical techniques' agnostic of the mesoscopic structure of real-world networks.
The role of peer groups in adolescents' educational trajectories
2009
The present study investigated whether the members of adolescents' peer groups show similar educational trajectories from comprehensive school to either senior secondary or vocational education, and to what extent their educational expectations, academic achievement, family structure, and parents' SES predict these trajectories. Five hundred thirty adolescents filled in a questionnaire focusing on their educational expectations, academic achievement and family background variables before the transition to post-comprehensive education. They were also asked to nominate three peers with whom they most liked to spend their time. After the transition, they reported the school form they were in. …
Achieving energy efficiency in data centers with a performance-guaranteed power aware routing
2017
Nowadays, data centers are designed to offer the highest performance in case of high traffic load and peak utilisation of the network. However, in a realistic data center environment, the peak capacity of the network is rarely reached and the average utilisation of devices varies between 5% and 25% which results into a huge loss of energy since most of the time links and servers are idle or under-utilized. The high impact of this wasted power on environmental effects, energy needs and electricity costs raised the concerns to seek for an efficient solution to make data centers more power effective while keeping the desired quality of service. In this paper, we propose a power-aware routing a…
Stability and -gain controller design for positive switched systems with mixed time-varying delays
2013
This paper investigates the problems of stability and L"1-gain controller design for positive switched systems with mixed time-varying delays. The mixed time-varying delays are presented in the forms of discrete delay and distributed delay. The purpose of this paper is to design a class of switching signals and a state feedback controller for the considered system such that the resulting closed-loop system is exponentially stable with L"1-gain performance. By constructing an appropriate co-positive type Lyapunov-Krasovskii functional and using the average dwell time approach, we propose a sufficient condition to ensure the exponential stability with weighted L"1-gain performance for the sys…