Les technologies de l’information et de la communication dans un contexte universitaire de crise

Résumé : L’étude présentée dans cet article met en perspective la manière dont des enseignants d’une université algérienne ont affronté, durant la pandémie de la Covid-19, la situation du passage d’un enseignement en présentiel à un enseignement à distance. L’utilisation des technologies de l’information et de la communication s’imposait et constituait une solution au problème de continuité des études universitaires et à la réactualisation continuelle des contenues et des pratiques enseignantes. Malheureusement, Cette situation de crise s’est heurtée à beaucoup de difficultés de non maîtrise de l’outil informatique et de non-disponibilité des moyens. Cet article vise, justement, à interroger les enjeux du recours aux TIC en pédagogie universitaire durant cette période de crise. Mots-clés : TIC, enseignant, université, apprenant, enseignement à distanc

Exponential Smoothing for Off-Policy Learning

Off-policy learning (OPL) aims at finding improved policies from logged bandit data, often by minimizing the inverse propensity scoring (IPS) estimator of the risk. In this work, we investigate a smooth regularization for IPS, for which we derive a two-sided PAC-Bayes generalization bound. The bound is tractable, scalable, interpretable and provides learning certificates. In particular, it is also valid for standard IPS without making the assumption that the importance weights are bounded. We demonstrate the relevance of our approach and its favorable performance through a set of learning tasks. Since our bound holds for standard IPS, we are able to provide insight into when regularizing IPS is useful. Namely, we identify cases where regularization might not be needed. This goes against the belief that, in practice, clipped IPS often enjoys favorable performance than standard IPS in OPL.Comment: ICML 2023 (Oral and Poster

COVID-19 and pregnancy: the fruitful experience of the university hospital of Tangier Morocco with hydroxychloroquine and anti-retroviral treatment

The coronavirus disease 2019 (COVID-19) caused by the emerging virus, severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2), was announced as a pandemic by the World Health Organization as a global public health emergency. Since the first case of COVID-19 was declared the Moroccan government set up drastic preventative measures to deal with the spread of the virus such as compulsory containment, telework, distance education, use of masks in public places, and many other preventive measures. Pregnant women require special attention in relation to prevention, diagnosis and management. We herein reported a prospective observational study that aims to evaluate the security and effectiveness of hydroxychloroquine on pregnant women with corona virus disease. Our study is a prospective study performed in the three hospitals specialized on corona virus disease 2019 in tangier morocco. We included pregnant women hospitalized with COVID-19 and reproductive-aged. Most cases took the hydroxychloroquine treatment. The maternal outcomes under hydroxychloroquine appear good in most cases for both mother and child and seemed to be safe according to several studies on its use for rheumatic diseases. In the absence of more robust data, this treatment might be best practice in countries that can’t afford the expensive antiviral treatment in this outbreak especially in emergency situations

The Critical Role of Hypoxia in Tumor-Mediated Immunosuppression

Underestimated for a long time, the involvement of the microenvironment has been proven essential for a better understanding of the cancer development. In keeping with this, the tumor is not considered anymore as a mass of malignant cells, but rather as an organ composed of various malignant and nonmalignant cell populations interacting with each other to create the tumor microenvironment. The tumor immune contexture plays a critical role in shaping the tumor immune response, and it is now well supported that such an immune response is impacted by the hypoxic stress within the tumor microenvironment. Tumor hypoxia is closely linked to tumor progression, metastasis, treatment failure, and escape from immune surveillance. Thus, hypoxia seems to be a key factor involved in creating an immune-suppressive tumor by multiple overlapping mechanisms, including the impairment of the function of cytotoxic immune cells, increasing the immunosuppressive properties of immunosuppressive cells, and activating resistance mechanism in the tumor cells. In this chapter, we review some recent findings describing how hypoxic stress in the tumor microenvironment hijacks the antitumor immune response

Offline Evaluation of Reward-Optimizing Recommender Systems: The Case of Simulation

Both in academic and industry-based research, online evaluation methods are seen as the golden standard for interactive applications like recommendation systems. Naturally, the reason for this is that we can directly measure utility metrics that rely on interventions, being the recommendations that are being shown to users. Nevertheless, online evaluation methods are costly for a number of reasons, and a clear need remains for reliable offline evaluation procedures. In industry, offline metrics are often used as a first-line evaluation to generate promising candidate models to evaluate online. In academic work, limited access to online systems makes offline metrics the de facto approach to validating novel methods. Two classes of offline metrics exist: proxy-based methods, and counterfactual methods. The first class is often poorly correlated with the online metrics we care about, and the latter class only provides theoretical guarantees under assumptions that cannot be fulfilled in real-world environments. Here, we make the case that simulation-based comparisons provide ways forward beyond offline metrics, and argue that they are a preferable means of evaluation.Comment: Accepted at the ACM RecSys 2021 Workshop on Simulation Methods for Recommender System

Mesoporous Co3O4 as a New Catalyst for Allylic Oxidation of Cyclohexene

Mesoporous cobalt oxide was investigated for the liquid phase oxidation of cyclohexene using tertiobutylhydroperoxide (TBHP) as an oxidant. The results were compared with several series of supported cobalt catalysts to study the influence of the cobalt loading and solvents on the overall conversion and selectivity. Mesoporous cobalt was synthesized through the nanocasting route using siliceous SBA-15 mesoporous material as a hard template and cobalt nitrate as the cobalt oxide precursor. Supported cobalt oxide catalysts (Co/MxOy) were synthesized by the impregnation method using two loadings (1 and 5 wt.%) and Al2O3, TiO2, and ZrO2 as supports. Samples were characterised by means: elemental analysis, X-ray powder Diffraction (XRD), BET (surface area), UV-Vis DR Spectroscopy, and MET. The results obtained showed that the cobalt oxide retains the mesoporous structure of SBA-15, and in all Co/MxOy, crystalline Co3O4 and CoO phases are observed. The mesoporous cobalt oxide is more active than the supported cobalt catalysts in the allylic oxidation of cyclohexene, with a conversion of 78 % of cyclohexene and 43.3 % selectivity toward 2-cyclohexene-1-ol. The highest activity of mesoporous cobalt oxide could be ascribed to its largest surface area. Furthermore, Co3O4 has both Lewis and Brönsted acidic sites whereas Co/MxOy has only Lewis acidic sites, which could also explain its superior catalytic activity. Moreover, mesoporous cobalt oxide was more stable than supported cobalt catalysts. Therefore, this catalyst is promising for allylic oxidation of alkenes.  Copyright © 2019 BCREC Group. All rights reserve

3D infrared thermospectroscopic imaging

AbstractThis work reports a multispectral tomography technique in transmission mode (called 3DITI for 3D Infrared Thermospectroscopic Imaging) based on a middle wavelength infrared (MWIR) focal plane array. This technique relies on an MWIR camera (1.5 to 5.5 μm) used in combination with a multispectral IR monochromator (400 nm to 20 μm), and a sample mounted on a rotary stage for the measurement of its transmittance at several angular positions. Based on the projections expressed in terms of a sinogram, spatial three-dimensional (3D) cubes (proper emission and absorptivity) are reconstructed using a back-projection method based on inverse Radon transform. As a validation case, IR absorptivity tomography of a reflective metallic screw is performed within a very short time, i.e., shorter than 1 min, to monitor 72 angular positions of the sample. Then, the absorptivity and proper emission tomographies of a butane-propane-air burner flame and microfluidic perfluoroalkoxy (PFA) tubing filled with water and ethanol are obtained. These unique data evidence that 3D thermo-chemical information in complex semi-transparent media can be obtained using the proposed 3DITI method. Moreover, this measurement technique presents new problems in the acquisition, storage and processing of big data. In fact, the quantity of reconstructed data can reach several TB (a tomographic sample cube of 1.5 × 1.5 × 3 cm3 is composed of more than 1 million pixels per wavelength)

High power density laser estimation using quantitative thermal imaging method

The knowledge of the amplitude and the spatial distribution of an excitation flux is of great interest for the quantification of heat sources. In this work, the development of a non-contact imaging powermeter based on the association of a bolometer with an infrared camera is described. This powermeter allows, thanks to infrared thermographic measurements and image processing methods, the quantitative estimation of the spatial distribution of the power of the flux delivered by a high-power laser. First, the experimental setup used is described. Then, the complete model- ling of the heat transfer within the bolometer using the 3D thermal quadrupole formalism is presented. After that, an inverse method based on the Wiener filter in Fourier-Laplace transform spaces to estimate the spatial distribution of the power flux is described. Finally, power estimation results using two metallic plates as a bolometer are presented and discusse

Active thermo-reflectometry for absolute temperature measurement by infrared thermography on specular materials

AbstractKnowledge of material emissivity maps and their true temperatures is of great interest for contactless process monitoring and control with infrared cameras when strong heat transfer and temperature change are involved. This approach is always followed by emissivity or reflections issues. In this work, we describe the development of a contactless infrared imaging technique based on the pyro-reflectometry approach and a specular model of the material reflection in order to overcome emissivities and reflections problems. This approach enables in situ and real-time identification of emissivity fields and autocalibration of the radiative intensity leaving the sample by using a black body equivalent ratio. This is done to obtain the absolute temperature field of any specular material using the infrared wavelength. The presented set up works for both camera and pyrometer regardless of the spectral range. The proposed method is evaluated at room temperature with several heterogeneous samples covering a large range of emissivity values. From these emissivity fields, raw and heterogeneous measured radiative fluxes are transformed into complete absolute temperature fields

Multiscale aspects of the response of a temperature field to a pulsed laser or a periodic laser spot: some applications for IR thermography for non destructive evaluation, terahertz tomography, super-resolution, and microscale heat transfer

The study of the response of a temperature field (recorded from IR cameras) to a laser spot heating is increasingly used for NDE (Non Destructive Evaluation) applications. The most classical type of application is to use the flying spot in order to detect vertical cracks and/or to measure the in plane thermal diffusivity in relation to the observation plane of opaque materials. But several other ways of applications are presented here related to tomography and also super resolution. Instead of opaque materials applications, the tomography is using the principles of the flying spot. It consists in an indirect detection on an intermediate layer (the thermoconverter) that can convert a wide range of radiation from the spot. The objective of super-resolution can also be implemented with flying spot in order to circumvent the low spatial resolution of IR imaging systems. Such methods consider spots whose diameter is small compared to the size of the pixel. Some applications of our team will be shown with multiscale considerations