Práticas pedagógicas para a construção do conceito de número: o que dizem os documentos do arquivo Lucília Bechara Sanchez?

Disponível em: https://www.fe.unicamp.br/revistas/ged/zetetike/article/view/4358Este texto apresenta os resultados de pesquisa que investigou as práticas pedagógicas para o ensino do conceito de número. O trabalho situa-se no que é possível denominar “era cognitivista no ensino de matemática” (1960-1980). Levou-se em conta o Arquivo Lucília Bechara Sanchez – APLBS – como fonte de pesquisa, para dar resposta à seguinte questão: De que modo o Movimento da Matemática Moderna – MMM – concretizou propostas para o ensino do conceito de número nas séries iniciais

The use of Lorentz microscopy for the determination of magnetic reversal mechanism of exchange-biased Co30Fe70/NiMn bilayer

Lorentz transmission electron microscopy (LTEM) combined with in-situ magnetizing experiments is a powerful tool for the investigation of the magnetization of the reversal process at the micron scale. We have implemented this tool on a conventional transmission electron microscope (TEM) to study the exchange anisotropy of a polycrystalline Co35Fe65/NiMn bilayer. Semi-quantitative maps of the magnetic induction were obtained at different field values by the differential phase contrast (DPC) technique adapted for a TEM (SIDPC). The hysteresis loop of the bilayer has been calculated from the relative intensity of magnetic maps. The curve shows the appearance of an exchange-bias field reveals with two distinct reversal modes of the magnetization: the first path corresponds to a reversal by wall propagation when the applied field is parallel to the anisotropy direction whereas the second is a reversal by coherent rotation of magnetic moments when the field is applied antiparallel to unidirectional anisotropy direction

Outburst of Comet 17P/Holmes Observed With The Solar Mass Ejection Imager

We present time-resolved photometric observations of Jupiter family comet 17P/Holmes during its dramatic outburst of 2007. The observations, from the orbiting Solar Mass Ejection Imager (SMEI), provide the most complete measure of the whole-coma brightness, free from the effects of instrumental saturation and with a time-resolution well-matched to the rapid brightening of the comet. The lightcurve is divided into two distinct parts. A rapid rise between the first SMEI observation on UT 2007 October 24 06h 37m (mid-integration) and UT 2007 October 25, is followed by a slow decline until the last SMEI observation on UT 2008 April 6 22h 16m (mid-integration). We find that the rate of change of the brightness is reasonably well-described by a Gaussian function having a central time of UT 2007 October 24.54+/-0.01 and a full-width-at-half-maximum 0.44+/-0.02 days. The maximum rate of brightening occurs some 1.2 days after the onset of activity. At the peak the scattering cross-section grows at 1070+/-40 km^2/s while the (model-dependent) mass loss rates inferred from the lightcurve reach a maximum at 3+/-10^5 kg/s. The integrated mass in the coma lies in the range (2 to 90)x10^10 kg, corresponding to 0.2% to 10% of the nucleus mass, while the kinetic energy of the ejecta is (0.6 to 30) MTonnes TNT. The particulate coma mass could be contained within a shell on the nucleus of thickness ~1.5 to 60 m. This is comparable to the distance traveled by conducted heat in the century since the previous outburst of 17P/Holmes. This coincidence is consistent with, but does not prove, the idea that the outburst was triggered by the action of conducted heat, possibly through the crystallization of buried amorphous ice.Comment: 27 pages, 8 figures; http://www2.ess.ucla.edu/~jingli/Holmes_SMEI/17P_Holmes.htm

Path representation of su(2)_k states II: Operator construction of the fermionic character and spin-1/2--RSOS factorization

This is the second of two articles (independent of each other) devoted to the analysis of the path description of the states in su(2)_k WZW models. Here we present a constructive derivation of the fermionic character at level k based on these paths. The starting point is the expression of a path in terms of a sequence of nonlocal (formal) operators acting on the vacuum ground-state path. Within this framework, the key step is the construction of the level-k operator sequences out of those at level-1 by the action of a new type of operators. These actions of operators on operators turn out to have a path interpretation: these paths are precisely the finitized RSOS paths related to the unitary minimal models M(k+1,k+2). We thus unravel -- at the level of the path representation of the states --, a direct factorization into a k=1 spinon part times a RSOS factor. It is also pointed out that since there are two fermionic forms describing these finite RSOS paths, the resulting fermionic su(2)_k characters arise in two versions. Finally, the relation between the present construction and the Nagoya spectral decomposition of the path space is sketched.Comment: 28 page

Impact de l’organisation sur la définition d’une profession au sein du SAMU : le cas des assistants de régulation médicale

National audienceWithin the Emergency Medical Service (EMS), Medical Regulation Assistant (MRA) are in the front line when it comes to managing emergencies. MRA is the first point of contact to take charge of callers. This feature, in the heart of the functioning and prerogatives of EMS is at the crossroads of medical emergency services in the covered area. Even if the objectives and prerogatives of MRA are set nationally, it appears that the skills and responsibilities associated with this function may vary from one region to another and from one EMS to another. In our work, we propose to question the ARM professionalization process by conducting an ethnographic survey and interviews within the EMS from the Arras Hospital. It will highlight the process by which MRA build their own skills and knowledge. We also show that this improving professionalism is literally described in the documents produced by the sector. Furthermore, professionalism requires constant adaptation to the technical, organizational and territorial constraints. This issue is being addressed in the EQU 2 project (Ethics, Quality, Emergency) which is a collaboration of two laboratories (GERIICO and STL, University of Lille) and the EMS from the Arras Hospital.Au sein du SAMU, les assistants de régulation médicale (ARM) sont en première ligne lorsqu’il est question de gérer les urgences. L’ARM est le premier interlocuteur à prendre en charge les appelants. Cette fonction, au cœur du fonctionnement et des prérogatives du SAMU est donc au carrefour des services de prise en charge médicale d’urgence de la zone couverte. Si les objectifs et les prérogatives des ARM sont définies nationalement, il s’avère que les compétences et les responsabilités associées à cette fonction peuvent varier d’une région à l’autre, d’un SAMU à l’autre. Dans le cadre de nos travaux, nous proposons de questionner le processus de professionnalisation des ARM en menant une enquête ethnographique et des entretiens au sein du SAMU du centre hospitalier D’Arras. Dans cet article, il s’agira de mettre en lumière le processus par lequel les ARM construisent eux-mêmes des compétences et des savoirs. Nous montrerons également que cette professionnalisation, qui s’inscrit textuellement dans les documents produits par le secteur, nécessite une constante adaptation aux contraintes techniques, territoriales et organisationnelles. Cette analyse s’inscrit dans le cadre du projet EQU 2 (Éthique, Qualité, Urgence) faisant collaborer les laboratoires GERiiCO (Sciences de l’information et de la communication ; Université de Lille) et STL (Savoirs, Textes, Langage ; Université de Lille) ainsi que le SAMU du Centre Hospitalier d’Arras

Comparative Effects of University of Wisconsin and Euro-Collins Solutions on Pulmonary Mitochondrial Function after Ischemia and Reperfusion

peer reviewedBACKGROUND: The aim of this study was to compare the effects of Euro-Collins and University of Wisconsin solutions on pulmonary mitochondrial function after cold ischemia and subsequent warm reperfusion. METHODS: Seventeen pigs underwent lung harvesting after classical lung flush with either University of Wisconsin or Euro-Collins solutions. The mitochondria were isolated from fresh swine lungs, from swine lungs subjected to 24 hr of cold ischemia, and from swine lungs subjected to 24 hr of ischemia followed by 30 min of subsequent ex vivo reperfusion at 37 degrees C with Krebs-Henseleit buffer solution and air ventilation. Mitochondrial oxidative phosphorylation parameters were determined in isolated mitochondria by in vitro measurement of oxygen consumption rates. During reperfusion, the lung function was assessed by the pulmonary aerodynamic parameters and the pulmonary vascular resistance. RESULTS: Relative to controls, mitochondria submitted to cold ischemia showed an alteration in the oxidoreductase activities of the respiratory chain. However, the yield of oxidative phosphorylation was conserved. After reperfusion, pulmonary mitochondria underwent a significant worsening in the oxidoreductase activities of the respiratory chain, and a decrease in the respiratory control and the efficiency of oxidative phosphorylation. Meanwhile, the reperfused lungs showed evidence of early dysfunction, assessed by the aerodynamic parameters and pulmonary vascular resistance. In this model, there was no advantage of University of Wisconsin solution over Euro-Collins solution. CONCLUSIONS: The mild mitochondrial alterations after cold ischemia were not sufficient to explain the limited tolerance of lung to ischemia. After reperfusion, the mitochondrial damage was more severe and could be involved in the posttransplant lung dysfunction

Electromodulated infrared spectroscopy of methanol electrooxidation on electrodispersed platinum electrodes: Enhancement of reactive intermediates

EMIRS spectra of the surface species resulting from methanol electrosorption on electrodispersed Pt were obtained by working under a wide range of experimental conditions, i.e. electrode roughness factor, methanol concentration and mean modulation potential. The intensity of the absorption band related to linearly adsorbed CO-species, COL, at ca. 2030–2080 cm−1 decreases on increasing the electrode roughness factor, a fact which is interpreted as a decrease in the CO adsorbate poisoning effect on electrodispersed Pt surfaces. As a consequence, under well-defined conditions, several bands are observed which might be assigned to adsorbed intermediates and reactive species. EMIRS also reveals a competition between COB and COL at high surface coverages. Spectral data for methanol electrooxidation on electrodispersed electrodes correlate well with the expected structure of this type of electrode.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Electromodulated infrared spectroscopy of methanol electrooxidation on electrodispersed platinum electrodes: Enhancement of reactive intermediates

EMIRS spectra of the surface species resulting from methanol electrosorption on electrodispersed Pt were obtained by working under a wide range of experimental conditions, i.e. electrode roughness factor, methanol concentration and mean modulation potential. The intensity of the absorption band related to linearly adsorbed CO-species, COL, at ca. 2030–2080 cm−1 decreases on increasing the electrode roughness factor, a fact which is interpreted as a decrease in the CO adsorbate poisoning effect on electrodispersed Pt surfaces. As a consequence, under well-defined conditions, several bands are observed which might be assigned to adsorbed intermediates and reactive species. EMIRS also reveals a competition between COB and COL at high surface coverages. Spectral data for methanol electrooxidation on electrodispersed electrodes correlate well with the expected structure of this type of electrode.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Effects of Propofol on Endotoxin-Induced Acute Lung Injury in Rabbit

This study was undertaken to clarify the effects of propofol on endotoxin-induced acute lung injury. Rabbits were randomly assigned to one of four groups. Each group received intravenous infusion of saline only, saline and Escherichia coli endotoxin, propofol (1 mg/kg bolus, then 5 mg/kg/hr) and endotoxin, or propofol (4 mg/kg bolus, then 20 mg/kg/hr) and endotoxin respectively. Infusion of saline or propofol was started 0.5 hr before the infusion of saline or endotoxin, and continued for 6 hr thereafter. The lungs of rabbits were ventilated with 40% oxygen. Mean blood pressure, heart rate, arterial oxygen tension (PaO2), and peripheral blood leukocyte and platelet count were recorded. The wet/dry (W/D) weight ratio of lung and lung injury score were measured, and analysis of bronchoalveolar lavage fluid (BALF) was done. Endotoxin decreased PaO2, and peripheral blood leukocyte and platelet count. And it increased W/D ratio of lung, lung injury score and leukocyte count, percentage of PMN cells, concentration of albumin, thromboxane B2 and IL-8 in BALF. Propofol attenuated all these changes except the leukocyte count in peripheral blood. In conclusion, propofol attenuated endotoxin-induced acute lung injury in rabbits mainly by inhibiting neutrophil and IL-8 responses, which may play a central role in sepsis-related lung injury

Consequences of Cold and Warm Ischemia on Pulmonary Mitochondrial Respiratory Function

IN RECENT years, pulmonary transplantation has become the treatment of choice for several end-stage lung diseases, but remains limited by the scarcity of suitable donors and the lack of reliable prolonged method of lung preservation.1 Transplantation of lung 6 hours postharvest leads to an increased incidence of primary graft dysfunction, due in part to ischemic damage of pulmonary cell structure and metabolism, and to acute reperfusion injury. However, very little is known about the real mechanisms of pulmonary cell injuries before, during, and after lung transplantation. During ischemia, the cytosolic and mitochondrial adenine nucleotide content falls,2,3 phospholipids are degraded, membrane permeabilities are increased, and the cytosolic levels of Na+, Ca2+ and phosphate are raised.4 Thus, cold and warm ischemia may induce cell dysfunctions and irreversible injuries responsible for necrosis. As mitochondia are believed to be the site of the determinants of irreversibility,5 the study of permanent oxidative phosphorylation damage after ischemia should be of great interest. The aim of this present study was to investigate the consequences of warm and cold ischemia on the oxidative phosphorylation of isolated lung mitochondri