L’accompagnement entrepreneurial : Proposition d’une lecture critique

L’accompagnement entrepreneurial est un enjeu important pour le développement économique de nos sociétés. A la lumière de cet enjeu, l’article propose un regard critique en matière d’accompagnement entrepreneurial à travers les paradigmes utilisés. Les auteurs, en mobilisant une grille de lecture de l’accompagnement utilisé en psychosociologie, montrent que l’accompagnement entrepreneurial a été envisagé essentiellement dans une logique rationnelle et normative autour de la posture du réparateur. De ce constat, les auteurs proposent d’envisager l’accompagnement entrepreneurial sous un regard paradigmatique différent : celui du facilitateur. A partir d’une recherche-intervention, ils montrent l’apport de ce type de démarche pour l’accompagnement entrepreneurial

APOIO PARA OS EMPREENDEDORES NA CONCEPÇÃO DE SUA VISÃO

The concept of vision has often been used in research on micro, small and medium enterprises (SMEs). In the study presented here, we note that so far little has been studied on the way entrepreneurs, the primary actors in SMEs, conceive a vision of their businesses and, thus, the manner in which they solve initial problematic situations. This article proposes the development of a method for generating entrepreneurial vision. From the concept of vision, we present a method created through a process of action study. This method has been tested in thirty entrepreneurial projects. At the end of the article, we review only the mechanisms used for conceiving the vision and highlight the contribution made ​​here to strengthen the entrepreneurial process.El concepto de Visión ha sido frecuentemente utilizado en las actividades de investigación referentes al estudio de las Micro, Pequeñas y Medianas Empresas (MIPYMES). A través de esta investigación hemos encontrado que poco se ha trabajado sobre la manera de cómo los emprendedores, principales actores de las MIPYMES, llegan a concebir su Visión sobre el negocio y así, la manera de resolver una situación problemática detonadora de acción. Este artículo propone el desarrollo de un método para la generación de una Visión en los emprendedores. A partir del concepto de Visión, presentamos un método desarrollado gracias a un proceso de investigación-acción. Este método se experimentó sobre treinta proyectos emprendedores. Al final del artículo, volvemos no sólo sobre los mecanismos utilizados para la concepción de la Visión, sino también sobre la contribución metodológica propuesta para fortalecer el proceso emprendedor.O conceito de visão tem sido frequentemente utilizado nas pesquisas sobre as micro, pequenas e médias empresas (PMEs). Na pesquisa aqui apresentada, pudemos notar que pouco se estudou até agora sobre a maneira como os empreendedores, principais atores das PMEs, concebem uma visão sobre seus negócios e, assim, sobre a maneira de resolver uma situação problemática iniciadora de ação. Este artigo propõe o desenvolvimento de um método para a geração da visão de empreendedores. A partir do conceito de visão, apresentamos um método criado graças a um processo de pesquisa-ação. Tal método foi experimentado em trinta projetos empreendedores. Ao final do artigo, retomamos apenas os mecanismos utilizados para a concepção da visão e destacamos a contribuição aqui feita para fortalecer o processo empreendedor

Energy measurement of fast neutron fields with a Recoil Proton Telescope using active pixel sensors

The spectrometer ATHENA (Accurate Telescope for High Energy Neutron metrology Applications), in development at the LNE-IRSN, characterizes energy and fluence of fast neutron fields. The detector is a Recoil Proton Telescope and measures neutron energies in the range of 5 to 20 MeV. The system is intended to become a primary standard for both energy and fluence measurements. The most innovative part of ATHENA is made of three CMOS pixel sensors, thinned down to 50 microns thickness, allowing an accurate tracking of the recoil. The use of CMOS sensors and a thick silicon diode increase the intrinsic efficiency of the detector by a factor of ten compared with conventional designs. In this paper, we demonstrate the ability of the detector to measure neutron energies in the range of 5 to 20 MeV. Experimental investigations, using mono-energetic neutron fields produced by the AMANDE facility, indicate a good reconstruction of neutron energies. The present design is still under development. The accuracy of measuring 5 MeV and 14 MeV neutron energies was 15% and 5%, respectively

Un nouveau type de matière active explique la formation d’agrégats bactériens et leur impact sur l’infection à méningocoque

International audienc

Melatonin Promotes Oligodendroglial Maturation of Injured White Matter in Neonatal Rats

OBJECTIVE:To investigate the effects of melatonin treatment in a rat model of white matter damage (WMD) in the developing brain. Additionally, we aim to delineate the cellular mechanisms of melatonin effect on the oligodendroglial cell lineage. METHODS:A unilateral ligation of the uterine artery in pregnant rat at the embryonic day 17 induces fetal hypoxia and subsequent growth restriction (GR) in neonatal pups. GR and control pups received a daily intra-peritoneal injection of melatonin from birth to post-natal day (P) 3. RESULTS:Melatonin administration was associated with a dramatic decrease in microglial activation and astroglial reaction compared to untreated GR pups. At P14, melatonin prevented white matter myelination defects with an increased number of mature oligodendrocytes (APC-immunoreactive) in treated GR pups. Conversely, melatonin was not found to be associated with an increased density of total oligodendrocytes (Olig2-immunoreactive), suggesting that melatonin is able to promote oligodendrocyte maturation but not proliferation. These effects appear to be melatonin-receptor dependent and were reproduced in vitro. INTERPRETATION:These data suggest that melatonin has a strong protective effect on developing damaged white matter through decreased microglial activation and oligodendroglial maturation leading to a normalization of the myelination process. Consequently, melatonin should be a considered as an effective neuroprotective candidate not only in perinatal brain damage but also in inflammatory and demyelinating diseases observed in adults

Neuroprotective Effect of Inhaled Nitric Oxide on Excitotoxic-Induced Brain Damage in Neonatal Rat

BACKGROUND: Inhaled nitric oxide (iNO) is one of the most promising therapies used in neonates. However, little information is known about its impact on the developing brain submitted to excitotoxic challenge. METHODOLOGY/PRINCIPAL FINDINGS: We investigated here the effect of iNO in a neonatal model of excitotoxic brain lesions. Rat pups and their dams were placed in a chamber containing 20 ppm NO during the first week of life. At postnatal day (P)5, rat pups were submitted to intracranial injection of glutamate agonists. At P10, rat pups exposed to iNO exhibited a significant decrease of lesion size in both the white matter and cortical plate compared to controls. Microglia activation and astrogliosis were found significantly decreased in NO-exposed animals. This neuroprotective effect was associated with a significant decrease of several glutamate receptor subunits expression at P5. iNO was associated with an early (P1) downregulation of pCREB/pAkt expression and induced an increase in pAkt protein concentration in response to excitotoxic challenge (P7). CONCLUSION: This study is the first describe and investigate the neuroprotective effect of iNO in neonatal excitotoxic-induced brain damage. This effect may be mediated through CREB pathway and subsequent modulation of glutamate receptor subunits expression

Force Generation upon T Cell Receptor Engagement

T cells are major players of adaptive immune response in mammals. Recognition of an antigenic peptide in association with the major histocompatibility complex at the surface of an antigen presenting cell (APC) is a specific and sensitive process whose mechanism is not fully understood. The potential contribution of mechanical forces in the T cell activation process is increasingly debated, although these forces are scarcely defined and hold only limited experimental evidence. In this work, we have implemented a biomembrane force probe (BFP) setup and a model APC to explore the nature and the characteristics of the mechanical forces potentially generated upon engagement of the T cell receptor (TCR) and/or lymphocyte function-associated antigen-1 (LFA-1). We show that upon contact with a model APC coated with antibodies towards TCR-CD3, after a short latency, the T cell developed a timed sequence of pushing and pulling forces against its target. These processes were defined by their initial constant growth velocity and loading rate (force increase per unit of time). LFA-1 engagement together with TCR-CD3 reduced the growing speed during the pushing phase without triggering the same mechanical behavior when engaged alone. Intracellular Ca2+ concentration ([Ca2+]i) was monitored simultaneously to verify the cell commitment in the activation process. [Ca2+]i increased a few tens of seconds after the beginning of the pushing phase although no strong correlation appeared between the two events. The pushing phase was driven by actin polymerization. Tuning the BFP mechanical properties, we could show that the loading rate during the pulling phase increased with the target stiffness. This indicated that a mechanosensing mechanism is implemented in the early steps of the activation process. We provide here the first quantified description of force generation sequence upon local bidimensional engagement of TCR-CD3 and discuss its potential role in a T cell mechanically-regulated activation process

Measuring Cell Mechanical Properties Using Microindentation

International audienceQuantifying cell mechanical properties is of interest to better understand both physiological and pathological cellular processes. Cell mechanical properties are quantified by a finite set of parameters such as the effective Young's modulus or the effective viscosity. These parameters can be extracted by applying controlled forces to a cell and by quantifying the resulting deformation of the cell. Microindentation consists in pressing a cell with a calibrated spring terminated by a rigid tip and by measuring the resulting indentation of the cell. We have developed a microindentation technique that uses a flexible micropipette as a spring. The micropipette has a microbead at its tip, and this spherical geometry allows using analytical models to extract cell mechanical properties from microindentation experiments. We use another micropipette to hold the cell to be indented, which makes this technique well suited to study nonadherent cells, but we also describe how to use this technique on adherent cells