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Buenos Aires, Argentina

The University of San Andrés is an Argentine university located in the town of Victoria, Buenos Aires on the shores of the Rio de la Plata, in the metropolitan area of Greater Buenos Aires, Argentina. It is a small private institution, with approximately 900 undergraduate students and 500 graduate students. It is served by one of the largest private libraries in the country, Max von Buch. Maintaining over 70,000 volumes, the library was recognized by the Andrew W. Mellon Foundation though their Program for Latin American Libraries and Archives. The university provides more than 70 study abroad programs with universities in Europe, North America, Latin America, and Australia.San Andrés is the first intuition in Argentina to offer a double degree accredited by Grandes Ecoles ESCP-Europe. The main campus is located in the town of Victoria, San Fernando Partido . It also has offices in downtown Buenos Aires. Wikipedia.

Fraiman D.,CONICET | Fraiman D.,University of San Andres | Chialvo D.R.,CONICET | Chialvo D.R.,National University of Rosario | Chialvo D.R.,University of California at Los Angeles
Frontiers in Physiology | Year: 2012

The study of spontaneous fluctuations of brain activity, often referred as brain noise, is getting increasing attention in functional magnetic resonance imaging (fMRI) studies. Despite important efforts, much of the statistical properties of such fluctuations remain largely unknown. This work scrutinizes these fluctuations looking at specific statistical properties which are relevant to clarify its dynamical origins. Here, three statistical features which clearly differentiate brain data from naive expectations for random processes are uncovered: First, the variance of the fMRI mean signal as a function of the number of averaged voxels remains constant across a wide range of observed clusters sizes. Second, the anomalous behavior of the variance is originated by bursts of synchronized activity across regions, regardless of their widely different sizes. Finally, the correlation length (i.e., the length at which the correlation strength between two regions vanishes) as well as mutual information diverges with the cluster's size considered, such that arbitrarily large clusters exhibit the same collective dynamics than smaller ones. These three properties are known to be exclusive of complex systems exhibiting critical dynamics, where the spatio-temporal dynamics show these peculiar type of fluctuations. Thus, these findings are fully consistent with previous reports of brain critical dynamics, and are relevant for the interpretation of the role of fluctuations and variability in brain function in health and disease. © 2012 Fraiman and Chialvo. Source

Berrendero J.R.,Autonomous University of Madrid | Justel A.,Autonomous University of Madrid | Svarc M.,University of San Andres
Computational Statistics and Data Analysis | Year: 2011

A principal component method for multivariate functional data is proposed. Data can be arranged in a matrix whose elements are functions so that for each individual a vector of p functions is observed. This set of p curves is reduced to a small number of transformed functions, retaining as much information as possible. The criterion to measure the information loss is the integrated variance. Under mild regular conditions, it is proved that if the original functions are smooth this property is inherited by the principal components. A numerical procedure to obtain the smooth principal components is proposed and the goodness of the dimension reduction is assessed by two new measures of the proportion of explained variability. The method performs as expected in various controlled simulated data sets and provides interesting conclusions when it is applied to real data sets. © 2011 Elsevier B.V. All rights reserved. Source

Fraiman D.,University of San Andres | Fraiman D.,CONICET | Dawson S.P.,FCEN UBA | Dawson S.P.,CONICET
Physical Biology | Year: 2014

Puffs are localized Ca2 + signals that arise in oocytes in response to inositol 1,4,5-trisphosphate (IP3). They are the result of the liberation of Ca2 + from the endoplasmic reticulum through the coordinated opening of IP3 receptor/channels clustered at a functional release site. The presence of buffers that trap Ca2 + provides a mechanism that enriches the spatio-temporal dynamics of cytosolic calcium. The expression of different types of buffers along the cell's life provides a tool with which Ca2 + signals and their responses can be modulated. In this paper we extend the stochastic model of a cluster of IP3R-Ca2 + channels introduced previously to elucidate the effect of buffers on sequences of puffs at the same release site. We obtain analytically the probability laws of the interpuff time and of the number of channels that participate of the puffs. Furthermore, we show that under typical experimental conditions the effect of buffers can be accounted for in terms of a simple inhibiting function. Hence, by exploring different inhibiting functions we are able to study the effect of a variety of buffers on the puff size and interpuff time distributions. We find the somewhat counter-intuitive result that the addition of a fast Ca 2 + buffer can increase the average number of channels that participate of a puff. © 2014 IOP Publishing Ltd. Source

Steizel S.,University of San Andres | Rimbau-Gilabert E.,Applied Technology Internet
Computers in Human Behavior | Year: 2012

The globalization of work within organizations has generated a greater need for all types of workers to exert interpersonal influence through technology-mediated communication tools. This paper sheds light on the interpersonal relations process in virtual environments from the specific perspective of the choice of upward influence (UI) tactics. We suggest that virtual work settings may impact the UI tactic selected, as well as the communication medium used to enact it. In particular, we study whether the types of UI strategies found in physical environments are relevant in virtual work contexts. This research also analyzes the UI process in virtual work settings, as well as the role of communication media in that process. Results based on the qualitative analysis of the content of 14 interviews suggest that there is an influence tactic specific to virtual work relations. That tactic might be called intermediation and consists of finding an intermediary who is well connected to the target and can help define the best approach for the agent. In addition, workers often split their influence attempts into a two-step strategy in order to achieve better results, taking advantage of the capabilities of the media available for that purpose. © 2012 Elsevier Ltd. All rights reserved. Source

Alftren J.,Lund University | Penarrieta J.M.,Lund University | Penarrieta J.M.,University of San Andres | Bergenstahl B.,Lund University | Nilsson L.,Lund University
Food Hydrocolloids | Year: 2012

The molecular and emulsifying properties of gum arabic (GA) and mesquite gum (MG) were characterized using asymmetrical flow field-flow fractionation connected to multi-angle light scattering and refractive index detection. Properties such as molar mass, root-mean-square radius (rrms), hydrodynamic radius (rh), conformation, apparent densities and distribution of proteinaceous matter over the whole molar mass range were determined. GA displayed a low molar mass (3.4×105g/mol), protein-poor component (population 1) and a high molar mass (1.9×106g/mol), protein-rich component (population 2). MG displayed one molar mass population with an average molar mass of 1.1×106g/mol. For both GA and MG, the conformation (rrms/rh) was increasingly spherical with increasing molar mass. However, MG had higher values of rrms/rh for a specific molar mass suggesting differences in structure between GA and MG. The protein content increased with increasing molar mass for both gums, although to a higher extent for GA. Selective adsorption, during emulsification experiments, could be observed of population 2 of GA which may be due to a combination of the higher protein content and a more flexible structure rendering it more surface active than population 1. Comparing GA and MG in terms of emulsion stability, it could be concluded that GA-stabilized emulsions have considerably higher stability against coalescence. © 2011 Elsevier Ltd. Source

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