The Constitution of Algorithms

A laboratory study that investigates how algorithms come into existence. Algorithms—often associated with the terms big data, machine learning, or artificial intelligence—underlie the technologies we use every day, and disputes over the consequences, actual or potential, of new algorithms arise regularly. In this book, Florian Jaton offers a new way to study computerized methods, providing an account of where algorithms come from and how they are constituted, investigating the practical activities by which algorithms are progressively assembled rather than what they may suggest or require once they are assembled. Drawing on a four-year ethnographic study of a computer science laboratory that specialized in digital image processing, Jaton illuminates the invisible processes that are behind the development of algorithms. Tracing what he terms a set of intertwining courses of actions sharing common finalities, he describes the practical activity of creating algorithms through the lenses of ground-truthing, programming, and formulating. He first presents the building of ground truths, referential repositories that form the material basis for algorithms. Then, after considering programming's resistance to ethnographic scrutiny, he describes programming courses of action he attended at the laboratory. Finally, he offers an account of courses of action that successfully formulated some of the relationships among the data of a ground-truth database, revealing the links between ground-truthing, programming, and formulating activities—entangled processes that lead to the shaping of algorithms. In practice, ground-truthing, programming, and formulating form a whirlwind process, an emergent and intertwined agency

Modeling Chip Formation in Orthogonal Metal Cutting using Finite Element Analysis

This thesis presents the simulation of chip formation in orthogonal metal cutting to evaluate the predictive capabilities of finite element code DYNA 3D. The Johnson and Cook constitutive model for materials, OFHC Copper, Aluminum 2024 T351, and Aluminum 6061 T6 alloy were incorporated into the simulation to account for the effects of strain hardening, strain rate hardening, and thermal softening effects during machining. Calculated values for the Johnson and Cook constitutive constants for Aluminum 6061 T6 alloy were determined from the literature. The model was compared to experimentally measured shear angles, chip thickness, chip velocity, and forces from the literature to evaluate the accuracy of the finite element code for a range machining strain rates. In an attempt to determine the predictive capabilities of DYNA 3D a strain rate regime of 10+3 s-1 to 10+4 s-1 was defined as the optimal strain rate regime for the orthogonal metal cutting application

La coopération au quotidien :: un moyen pour améliorer le climat de classe ?

Cette recherche s’intéresse à la coopération au quotidien. Plus précisément sur les effets que celle-ci peut avoir sur l’élève et la classe. Dans un premier temps, la problématique apporte des informations théoriques, concernant l’histoire de la coopération, diverses définitions, ainsi que des informations pratiques avec quelques outils liés à la coopération. À partir de cette base théorique, j’ai réalisé des entretiens par autoconfrontation avec des élèves dans deux classes du cycle 2 utilisant la pratique de la coopération quotidiennement. Cette récolte de données a permis une analyse thématique dans le but de comprendre si la coopération améliore le climat de classe et permet de développer un sentiment d’appartenance au groupe classe

Methods for Real-Time PCR-Based Diagnosis of Chlamydia pneumoniae, Chlamydia psittaci, and Chlamydia abortus Infections in an Opened Molecular Diagnostic Platform.

The advances in molecular biology of the last decades have dramatically improved the field of diagnostic bacteriology. In particular, PCR-based technologies have impacted the diagnosis of infections caused by obligate intracellular bacteria such as pathogens from the Chlamydiacae family. Here, we describe a real-time PCR-based method using the Taqman technology for the diagnosis of Chlamydia pneumoniae, Chlamydia psittaci, and Chlamydia abortus infection. The method presented here can be applied to various clinical samples and can be adapted on opened molecular diagnostic platforms

Common skin infection due to Panton-Valentine leucocidin-producing Staphylococcus aureus strains in asylum seekers from Eritrea: a genome-based investigation of a suspected outbreak

Since late 2014, multiple cases of abscesses and boils due to methicillin-susceptible Staphylococcus aureus (MSSA) expressing the Panton-Valentine leucocidin (PVL) were observed in Eritrean asylum seekers in Lausanne, Switzerland. Strains isolated from infected Eritrean and non-Eritrean patients were compared by whole genome sequencing to determine whether these numerous cases result from an outbreak. The genome of S. aureus PVL-producing strains were sequenced and compared. Clinical and epidemiological characteristics of patients infected by PVL-producing strains were investigated. This work reports 15 cases of infections due to PVL-producing strains affecting mostly asylum seekers (n = 10), people working with refugees and/or exposed to Africans (n = 3). Most infections were due to closely related strains of CC152 (n = 8) and CC15 (n = 3), two distantly related (>34 000 core single nucleotide polymorphisms) clonal complexes. An epidemiological link between the 15 cases could be ruled out by whole genome sequencing (33 to 172 core single nucleotide polymorphisms between the different strains of a given complex). Altogether, these results reflect the probable high incidence of CC15 and CC152 PVL-producing strains in eastern Africa. Clinicians facing unusual skin infections in African refugees (or in any person returning from this region of high endemicity) should consider S. aureus PVL-producer before suspecting rare infections such as leishmaniasis or rickettsiosis. Clinicians should also remember that PVL are frequently expressed by MSSA in some regions of the world and that antibiotics that are efficient on toxin expression, such as clindamycin, represent the best therapeutic option