Robust short-term memory without synaptic learning

Short-term memory in the brain cannot in general be explained the way long-term memory can -- as a gradual modification of synaptic weights -- since it takes place too quickly. Theories based on some form of cellular bistability, however, do not seem able to account for the fact that noisy neurons can collectively store information in a robust manner. We show how a sufficiently clustered network of simple model neurons can be instantly induced into metastable states capable of retaining information for a short time (a few seconds). The mechanism is robust to different network topologies and kinds of neural model. This could constitute a viable means available to the brain for sensory and/or short-term memory with no need of synaptic learning. Relevant phenomena described by neurobiology and psychology, such as local synchronization of synaptic inputs and power-law statistics of forgetting avalanches, emerge naturally from this mechanism, and we suggest possible experiments to test its viability in more biological settings.Comment: 20 pages, 9 figures. Amended to include section on spiking neurons, with general rewrit

Racial Socioeconomic Inequality, Structural Disadvantage, and Neighborhood Crime: Testing the Relative and Absolute Deprivation Perspectives

Few studies of urban crime patterns have explored whether indicators of relative deprivation (e.g., income inequality) significantly associate with crime at the most theoretically appropriate level of analysis, the neighborhood; whether they do so net of controls for measures of absolute deprivation (e.g., structural disadvantage); and whether their effects vary by race/ethnicity. Drawing on data from the 2000 National Neighborhood Crime Study (NNCS) and census data extracted from the National Historical Geographic Information System (NHGIS), I explore these questions for overall, intraracial, and interracial inequality in income and educational attainment with respect to neighborhood homicide, burglary, and robbery rates. Their effects are compared across majority White, Black, and Latino census tracts embedded in a nationally representative sample of large U.S. cities. Consistent with prior research, I find that overall and intraracial inequality are more reliable predictors of neighborhood crime rates than interracial inequality, net of disadvantage; that the overall and intraracial inequality measures exert racially invariant effects only for homicide rates; and that for robbery and burglary rates, the most severe effects of these predictors are found in majority White neighborhoods. Although interracial inequality is never a significant covariate of homicide, it evinces an interesting pattern for the other two crime types: the largest effects are consistently found when the disadvantaged racial group in the comparison resides in neighborhoods where the more advantaged group is in the majority. Theoretical implications and directions for future research are discussed

The Past And Pending Using Cinema As A Dialogue To Break Down Walls In Communication

The Past and Pending is a feature-length documentary by Samuel Eliot Torres, made as part of the requirements for earning a Master of Fine Arts in Film & Digital Media from the University of Central Florida. The film focuses on a family torn apart by a major decision to migrate to the U.S. from Puerto Rico. The protagonist, Torres, is now trying to receive closure from the events by asking the questions he could not ask as a child, but feels compelled to ask as an adult. Filming with only one person in the crew allowed for an intimacy and spontaneity that is prized by entrepreneurial digital cinema makers. Without the financial and scheduling constraints of enlisting a large crew, the film was allowed to thrive with a spontaneous and ongoing shooting schedule, controlled entirely by one person

Nonlinear preferential rewiring in fixed-size networks as a diffusion process

We present an evolving network model in which the total numbers of nodes and edges are conserved, but in which edges are continuously rewired according to nonlinear preferential detachment and reattachment. Assuming power-law kernels with exponents alpha and beta, the stationary states the degree distributions evolve towards exhibit a second order phase transition - from relatively homogeneous to highly heterogeneous (with the emergence of starlike structures) at alpha = beta. Temporal evolution of the distribution in this critical regime is shown to follow a nonlinear diffusion equation, arriving at either pure or mixed power-laws, of exponents -alpha and 1-alpha

Determinants of researchgate (rg) score for the top 100 of Latin American universities at webometrics

This paper has the purpose of establishing the variables that explain the behavior of ResearchGate for the Top100 Latin American universities positioned in Webometrics database for January 2017. For this purpose, a search was carried out to get information about postgraduate courses and professors at the institutional websites and social networks, obtaining documents registered in Google Scholar. For the data analysis, the econometric technique of ordinary least squares was applied, a cross-sectional study for the year 2017 was conducted, and the individuals studied were the first 100 Latin American universities, obtaining a coefficient of determination of 73.82%. The results show that the most significant variables are the number of programs, the number of teacher’s profiles registered in Google Scholar, the number of subscribers to the institutional YouTube channel, and the GDP per capita of the university origin country. Variables such as (i) number of undergraduate programs, (ii) number of scientific journals; (iii) number of documents found under the university domain; (iv) H-index of the 1st profile of researcher at the university; (vi) number of members of the institution; (v) SIR Scimago ranking of Higher Education Institutions; (vi) number of tweets published in the institutional account; (vii) number of followers in the Twitter institutional account; (vii) number of “likes” given to the institutional count, were not significantCorporación Universitaria Minuto de Dios, Fundación Universitaria Konrad Lorenz, Universidad Nacional Experimental Politécnica, Universidad Centroccidental “Lisandro Alvarado, Universidad de la Costa

“EFICACIA DEL TRATAMIENTO CON GABAPENTINA PARA EL MANEJO DEL PRURITO EN PACIENTES CON ENFERMEDAD RENAL CRÓNICA EN TRATAMIENTO SUSTITUTIVO CON DIALISIS PERITONEAL”

El prurito ur̩mico es un síntoma común y desagradable en paciente con enfermedad renal crónica (ERC) afectando a 1/3 de pacientes en diálisis, con incidencia reportada entre 42 a 52 % e impacto en la calidad de vida de los pacientes. Varias hipótesis han sido propuestas para explicar la patog̩nesis del prurito ur̩mico, por lo que los tratamientos disponibles no son completamente efectivos

The entropic origin of disassortativity in complex networks

Why are most empirical networks, with the prominent exception of social ones, generically degree-degree anticorrelated, i.e. disassortative? With a view to answering this long-standing question, we define a general class of degree-degree correlated networks and obtain the associated Shannon entropy as a function of parameters. It turns out that the maximum entropy does not typically correspond to uncorrelated networks, but to either assortative (correlated) or disassortative (anticorrelated) ones. More specifically, for highly heterogeneous (scale-free) networks, the maximum entropy principle usually leads to disassortativity, providing a parsimonious explanation to the question above. Furthermore, by comparing the correlations measured in some real-world networks with those yielding maximum entropy for the same degree sequence, we find a remarkable agreement in various cases. Our approach provides a neutral model from which, in the absence of further knowledge regarding network evolution, one can obtain the expected value of correlations. In cases in which empirical observations deviate from the neutral predictions -- as happens in social networks -- one can then infer that there are specific correlating mechanisms at work.Comment: 4 pages, 4 figures. Accepted in Phys. Rev. Lett. (2010