Modeling Society with Statistical Mechanics: an Application to Cultural Contact and Immigration

We introduce a general modeling framework to predict the outcomes, at the population level, of individual psychology and behavior. The framework prescribes that researchers build a cost function that embodies knowledge of what trait values (opinions, behaviors, etc.) are favored by individual interactions under given social conditions. Predictions at the population level are then drawn using methods from statistical mechanics, a branch of theoretical physics born to link the microscopic and macroscopic behavior of physical systems. We demonstrate our approach building a model of cultural contact between two cultures (e.g., immigration), showing that it is possible to make predictions about how contact changes the two cultures

Commutative Languages and their Composition by Consensual Methods

Commutative languages with the semilinear property (SLIP) can be naturally recognized by real-time NLOG-SPACE multi-counter machines. We show that unions and concatenations of such languages can be similarly recognized, relying on -- and further developing, our recent results on the family of consensually regular (CREG) languages. A CREG language is defined by a regular language on the alphabet that includes the terminal alphabet and its marked copy. New conditions, for ensuring that the union or concatenation of CREG languages is closed, are presented and applied to the commutative SLIP languages. The paper contributes to the knowledge of the CREG family, and introduces novel techniques for language composition, based on arithmetic congruences that act as language signatures. Open problems are listed.Comment: In Proceedings AFL 2014, arXiv:1405.527

Mean field behaviour of spin systems with orthogonal interaction matrix

For the long-range deterministic spin models with glassy behaviour of Marinari, Parisi and Ritort we prove weighted factorization properties of the correlation functions which represent the natural generalization of the factorization rules valid for the Curie-Weiss case.Comment: Improved exposition, few typos and a combinatorial mistake corrected. (To appear in Journal of Statistical Physics

Social capital dynamics and collective action: the role of subjective satisfaction

In low income countries grass-root collective action is a well known substitute for government provision of public goods. In our research we wonder what is its effect on the law of motion of social capital, a crucial microeconomic determinant of economic development. To this purpose we structure a ?sandwich? experiment in which participants play a public good game (PGG) between two trust games (TG1 and TG2). Our findings show that the change in trustworthiness between the two trust game rounds generated by the PGG treatment is crucially affected by the subjective satisfaction about the PGG rather than by standard objective measures related to PGG players? behavior. These results highlight that subjective satisfaction after collective action has relevant predictive power on social capital creation providing information which can be crucial to design successful self-organized resource regimes.trust games, public good games, randomized experiment, social capital, subjective wellbeing

#Nevicata14

Nel 2104 l’amministrazione del Comune di Milano decide di incaricare la Triennale di Milano di coordinare il cosiddetto progetto Atelier Castello per analizzare proposte di riassetto provvisorio dello spazio del Foro Bonaparte. Atelier Castello nasce come percorso partecipato e aperto, con il coinvolgimento dei residenti, dei cittadini, dei comitati e del consiglio di zona. La pedonalizzazione della cosiddetta Piazza Castello era già in atto da qualche tempo, ma senza un progetto architettonico che la supportasse e il progetto da realizzare per la sola durata dell’imminente EXPO, avrebbe dovuto rappresentare un campo di prova per mettere a punto in modo cosciente i criteri per la futura e più definitiva sistemazione della piazza. Sono stati messi a confronto 11 studi di architettura, invitati da Triennale ad esporre le proprie idee e alla fine del processo il progetto scelto da una giuria di esperti è risultato quello dello studio Guidarini & Salvadeo che per l’occasione ha coinvolto SNARK. (SNARK si occupa di design relazionale, di processi decisionali, di co-progettazione, di percorsi partecipati e di comprensione di fenomeni complessi.) Il progetto ha assunto fin da subito un brand espresso attraverso il nome “#Nevicata14”, con il quale abbiamo voluto esprimere sia il carattere di provvisorietà sia la capacità del progetto di modificare, come dopo una nevicata, l’aspetto dello spazio e il suo uso. Il 13 dicembre 2014 una giuria nominata da Triennale di Milano, composta dal prof. arch. Marco Romano, prof. arch. Franco Purini, prof. arch. Paola Viganò, arch. Francesca Bavestrelli, alla presenza del presidente della Triennale di Milano ing. Claudio De Albertis e del coordinatore del progetto “Atelier Castello” prof. Arch. Alberto Ferlenga, ha assegnato il primo premio al progetto #Nevicata14

Improving fast generation of halo catalogs with higher-order Lagrangian perturbation theory

We present the latest version of Pinocchio, a code that generates catalogues of DM haloes in an approximate but fast way with respect to an N-body simulation. This code version extends the computation of particle and halo displacements up to 3rd-order Lagrangian Perturbation Theory (LPT), in contrast with previous versions that used Zeldovich approximation (ZA). We run Pinocchio on the same initial configuration of a reference N-body simulation, so that the comparison extends to the object-by-object level. We consider haloes at redshifts 0 and 1, using different LPT orders either for halo construction - where displacements are needed to decide particle accretion onto a halo or halo merging - or to compute halo final positions. We compare the clustering properties of Pinocchio haloes with those from the simulation by computing the power spectrum and 2-point correlation function (2PCF) in real and redshift space (monopole and quadrupole), the bispectrum and the phase difference of halo distributions. We find that 2LPT and 3LPT give noticeable improvement. 3LPT provides the best agreement with N-body when it is used to displace haloes, while 2LPT gives better results for constructing haloes. At the highest orders, linear bias is typically recovered at a few per cent level. In Fourier space and using 3LPT for halo displacements, the halo power spectrum is recovered to within 10 per cent up to $k_{max}\sim0.5\ h/$Mpc. The results presented in this paper have interesting implications for the generation of large ensemble of mock surveys aimed at accurately compute covariance matrices for clustering statistics.Comment: 20 pages, 20 figures, submitted to MNRA

Simulating realistic disk galaxies with a novel sub-resolution ISM model

We present results of cosmological simulations of disk galaxies carried out with the GADGET-3 TreePM+SPH code, where star formation and stellar feedback are described using our MUlti Phase Particle Integrator (MUPPI) model. This description is based on simple multi-phase model of the interstellar medium at unresolved scales, where mass and energy flows among the components are explicitly followed by solving a system of ordinary differential equations. Thermal energy from SNe is injected into the local hot phase, so as to avoid that it is promptly radiated away. A kinetic feedback prescription generates the massive outflows needed to avoid the over-production of stars. We use two sets of zoomed-in initial conditions of isolated cosmological halos with masses (2-3) * 10^{12} Msun, both available at several resolution levels. In all cases we obtain spiral galaxies with small bulge-over-total stellar mass ratios (B/T \approx 0.2), extended stellar and gas disks, flat rotation curves and realistic values of stellar masses. Gas profiles are relatively flat, molecular gas is found to dominate at the centre of galaxies, with star formation rates following the observed Schmidt-Kennicutt relation. Stars kinematically belonging to the bulge form early, while disk stars show a clear inside-out formation pattern and mostly form after redshift z=2. However, the baryon conversion efficiencies in our simulations differ from the relation given by Moster et al. (2010) at a 3 sigma level, thus indicating that our stellar disks are still too massive for the Dark Matter halo in which they reside. Results are found to be remarkably stable against resolution. This further demonstrates the feasibility of carrying out simulations producing a realistic population of galaxies within representative cosmological volumes, at a relatively modest resolution.Comment: 19 pages, 21 figures, MNRAS accepte

WIDAR: bistatic WI-fi Detection And Ranging for off-the-shelf devices

The huge spread of wireless networks and the success of location-aware applications require novel indoor po- sitioning mechanisms based on existing technologies such as IEEE 802.11. Taking inspiration from the RADAR, we propose WIDAR: a bistatic WI-fi Detection And Ranging system for off- the-shelf devices. WIDAR implementation is based on the USRP2 platform and is able to locate 802.11 stations while they operate in existing legacy networks. No substitution or repositioning of the Access Points is necessary. WIDAR works passively and does not expect any dedicated action from the target WiFi node. No airtime is wasted and the target cannot even detect that it is being ranged. Such features make WIDAR desirable in surveillance and monitoring applications where it can provide real-time tracking functionalities

A warm mode of gas accretion on forming galaxies

We present results from high--resolution cosmological hydrodynamical simulations of a Milky--Way-sized halo, aimed at studying the effect of feedback on the nature of gas accretion. Simulations include a model of inter-stellar medium and star formation, in which SN explosions provide effective thermal feedback. We distinguish between gas accretion onto the halo, which occurs when gas particles cross the halo virial radius, and gas accretion onto the central galaxy, which takes place when gas particles cross the inner one-tenth of the virial radius. Gas particles can be accreted through three different channels, depending on the maximum temperature value, $T_{\rm max}$, reached during the particles' past evolution: a cold channel for $T_{\rm max}10^6$K, and a warm one for intermediate values of $T_{\rm max}$. We find that the warm channel is at least as important as the cold one for gas accretion onto the central galaxy. This result is at variance with previous findings that the cold mode dominates gas accretion at high redshift. We ascribe this difference to the different supernova feedback scheme implemented in our simulations. While results presented so far in the literature are based on uneffective SN thermal feedback schemes and/or the presence of a kinetic feedback, our simulations include only effective thermal feedback. We argue that observational detections of a warm accretion mode in the high--redshift circum-galactic medium would provide useful constraints on the nature of the feedback that regulates star formation in galaxies.Comment: 6 pages, 3 figures, accepted for publication in ApJ