Dynamics and bifurcations of the adaptive exponential integrate-and-fire model

Recently, several two-dimensional spiking neuron models have been introduced, with the aim of reproducing the diversity of electrophysiological features displayed by real neurons while keeping a simple model, for simulation and analysis purposes. Among these models, the adaptive integrate-and-fire model is physiologically relevant in that its parameters can be easily related to physiological quantities. The interaction of the differential equations with the reset results in a rich and complex dynamical structure. We relate the subthreshold features of the model to the dynamical properties of the differential system and the spike patterns to the properties of a Poincaré map defined by the sequence of spikes. We find a complex bifurcation structure which has a direct interpretation in terms of spike trains. For some parameter values, spike patterns are chaotic

Spécificité des PME de services supérieurs françaises à l'international : le rôle des technologies de l'information et de la communication

International audienceThis article deals with International SMEs and their strategic management linked with information and communication technologies. We would like to know how International SMEs manage their distance and proximity with clients, when they are themselves in peripherical area. We will take as an example the case of French International SMEs. We will compare the difference in terms of ICT management between local or regional SMEs and European or International SMEs. First of all, we will present the state of Art of International Management Studies, then we will focus on the relations between ICT and Entreprises. Secondly, we will focus on the DISCOTEC study, with the development of the methodology, the sample chosen and the analysis of the ground. Finally we will discuss the results and open new perspectives and we will compare our work with other countries such as the Czech RepublicCet article s'intéresse aux PME Internationales et à la façon dont leur management mobilise les technologies de l'information et de la communication. Il s'agit de voir comment des PME à dimension internationale gèrent la distance et leur éloignement vis-à-vis de leurs clients, alors même qu'elles sont elles-mêmes situées dans des zones d'activités périphériques, dispersées sur un territoire donné en prenant le cas de la France comme exemple. Nous pourrons ainsi voir les différences existantes entre des entreprises à dimension régionale, voire nationale et des entreprises à dimension européenne ou mondiale, et comment elles gèrent leurs technologies de l'information et de la communication sur un territoire donné. Nous présenterons dans un premier temps un état de l'art sur la théorie du management des entreprises internationales et leurs relations à la proximité et/ou distance avec les TIC dans différentes régions françaises, surtout lorsque ces PME sont dans des zones blanches, c'est-à-dire exclues des grands axes et réseaux de communication (privées de fibre optique par exemple). Puis nous nous présenterons la méthodologie de l'enquête, le questionnaire et son traitement par le cabinet ENOV Research, les analyses menées et enfin nous nous concentrons sur les perspectives de recherche et notamment envisager la poursuite de ces travaux avec d'autres pays européens comme la république tchèque

Equation-oriented specification of neural models for simulations

Simulating biological neuronal networks is a core method of research in computational neuroscience. A full specification of such a network model includes a description of the dynamics and state changes of neurons and synapses, as well as the synaptic connectivity patterns and the initial values of all parameters. A standard approach in neuronal modeling software is to build network models based on a library of pre-defined components and mechanisms; if a model component does not yet exist, it has to be defined in a special-purpose or general low-level language and potentially be compiled and linked with the simulator. Here we propose an alternative approach that allows flexible definition of models by writing textual descriptions based on mathematical notation. We demonstrate that this approach allows the definition of a wide range of models with minimal syntax. Furthermore, such explicit model descriptions allow the generation of executable code for various target languages and devices, since the description is not tied to an implementation. Finally, this approach also has advantages for readability and reproducibility, because the model description is fully explicit, and because it can be automatically parsed and transformed into formatted descriptions. The presented approach has been implemented in the Brian2 simulator

Resolution of hyposmotic stress in isolated mouse ventricular myocytes causes sealing of t‐tubules

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98789/1/expphysiol.2013.072470.pd

Reconsidering the nature and effects of habits in urban transportation behavior

This article adds to the growing empirical evidence on the importance of habits in governing human behavior, and sheds new light on individual inertia in relation to transportation behavior. An enriched perspective rooted in Veblenian evolutionary economics (VEE) is used to construct a theoretical framework in order to analyze the processes at play in the formation and reinforcement of habits. The empirical study explores more specifically the synchronic processes strengthening the car-using habit. In addition to underlining the shortcomings of a 'decision theory' perspective to address urban transportation behaviors, we find that synchronic habits can have a significant effect on behavioral inertia. Our results suggest the existence of positive feedback between the development of synchronic habits, qualitative perceptions of driving times, and reinforcement of the car-using habit. The paper points out also that the diachronic dimension of habits would constitute another promising domain for further research on behavioral inertia in transportatio

The 'death of distance' fifteen years on. Information technology and knowledge-based service firms in rural areas.

Since the seminal paper by Beyers and Lindhal on 'lone eagles and high fliers' (1996), rural knowledge-based services have received little attention, although the landscape of the information economy has dramatically changed. This paper embraces a comparative approach which endeavours to explore the existence of a possible digital divide between rural and urban firms, all other things being equal. The need to capture a locational effect requires a strict control of sector and size. Through a telephone survey implemented in early 2011, 400 business service firms located in rural areas in the South-East of France were asked about their use of telecommunication-based applications. Then, a sample of 300 similar firms based in the metropolitan area of Lyon was given the same questionnaire. The empirical analysis found that rural firms are less versatile users of information technology than their urban equivalents. However, the gap is thin and is not the result of a lack of telecommunication infrastructures. These findings suggest that, in the French context, local economic development policies must not solely rely on the provision of broadband infrastructure and services, but also on the stimulation of entrepreneurship, the rise of entrepreneurial skills, and the global enhancement of the community's attractivity

Numerical Solution of Differential Equations by the Parker-Sochacki Method

A tutorial is presented which demonstrates the theory and usage of the Parker-Sochacki method of numerically solving systems of differential equations. Solutions are demonstrated for the case of projectile motion in air, and for the classical Newtonian N-body problem with mutual gravitational attraction.Comment: Added in July 2010: This tutorial has been posted since 1998 on a university web site, but has now been cited and praised in one or more refereed journals. I am therefore submitting it to the Cornell arXiv so that it may be read in response to its citations. See "Spiking neural network simulation: numerical integration with the Parker-Sochacki method:" J. Comput Neurosci, Robert D. Stewart & Wyeth Bair and http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717378