« Elles sont partout… » : Les femmes et la ville en temps d’épidémie, Montréal, 1918-1920

Cet article se penche sur les épidémies d’influenza de 1918 et (dans une moindre mesure) 1920, afin d’explorer les rapports entre les femmes montréalaises et la ville. À court terme, l’épidémie de 1918 fit de certains espaces publics des espaces dangereux ou interdits. Paradoxalement, elle engendra chez de nombreuses femmes de nouvelles connaissances de la ville ; elle leur permit de connaître la ville autrement. Nous examinons d’abord les efforts des infirmières, des religieuses et des bénévoles pour soigner les malades et les mourants. Nous démontrons que ces efforts ont donné à certaines Montréalaises un rôle dans la ville qui était non seulement « public », mais aussi publiquement reconnu. Leur travail fut doté d’une importance civique ; ces femmes étaient partie prenante dans la ville et dans la santé civique. Dans un deuxième temps, nous examinons les intrusions des « visiteurs », et surtout des « visiteuses », dans les maisons privées pendant l’épidémie, ainsi que leurs rapports avec les femmes qui y vivaient. Nous proposons que ces visites ont produit des connaissances inédites de la ville et surtout de ses domiciles et quartiers ouvriers. L’article se termine avec un « épilogue » qui considère quelques-unes des conséquences de ce moment singulier dans l’histoire de Montréal.This article uses the influenza epidemics of 1918 and (to a lesser extent) 1920 to explore Montreal women’s relationship to the city. It argues that although in the short term the 1918 epidemic made some parts of the city dangerous or « off-limits » to women, it paradoxically gave many women access to new knowledge about the city. The article looks first at the relief work undertaken by nurses, nuns, and volunteers on behalf of the sick and the dying. It argues that the relief efforts of Montreal women gave them a role that was not only « public » but also publicly recognized. Their work was considered to be of civic importance ; they were stakeholders in the city and in civic health. Second, the article looks at the intrusion of male and (especially) female « visitors » into private homes during the epidemic, as well as the relationships of these « visitors » with the women living there. It argues that these « visits » led to a heightened awareness of the city and especially of its working-class homes and neighbourhoods. A brief epilogue looks at some of the consequences of this particular moment in Montreal’s history

Magnetic polymer actuators for microfluidics

The manipulation of fluids on the sub-millimetre scale -microfluidics- finds application in the miniaturisation and integration of biological analysis, chemical synthesis, optics and information technology. In a microfluidic device, fluids need to be transported, mixed, separated and directed in and through a micro-scale system. The effcient mixing of fluids -particularly needed for analysis or synthesis -presents a large challenge in microfluidics. Mixing cannot occur by turbulence because of the low Reynolds number that prevails in micro-channels, and molecular diffusion is rather slow in achieving mixing on the scale of a microfluidic channel. A solution for obtaining mixing on efficient time scales has been to passively or actively manipulate the fluids to induce chaotic advection and increase the interfacial area of two fluids progressively, thereby decreasing the length scale over which diffusion has to take place to mix the fluids. In this thesis we investigate magnetic polymer micro-actuators that can be incorporated on the walls of microfluidic channels and can be actuated with magnetic fields. A magnetic stimulus that addresses micro-actuators is very robust, because of the low interaction between magnetic fields and (bio)chemical fluids. The use of polymeric materials for producing micro-actuators potentially allows for cost-effective micro-devices with integrated fluidic actuation. The aim of the thesis is to provide generic and advanced fluid control inside microfluidic devices, e.g: for the purpose of integrated pumping or for the purpose of mixing. Superparamagnetic and ferromagnetic particles have been dispersed in polymers with a low elastic modulus and the composites have been characterised mechanically and magnetically. A low elastic modulus polymer enables large deflections of micro-actuators with practical magnetic fields. In this thesis, various types of the elastomer polydimethylsiloxane (PDMS) have been used for constructing the polymeric micro-actuators with a low elastic modulus. The efficiency of magnetic actuation on small scales is discussed for two actuator concepts. It is shown that actuation by magnetic torque scales neutrally with miniaturisation, allowing for actuation with externally generated magnetic fields. In contrast, actuation by magnetic gradient force scales inversely proportional to the size of the actuator. Therefore magnetic gradient actuation cannot be induced by an external electromagnet and requires a localised generation of magnetic fields. Because viscous effects dominate over inertial effects at small scales (Reynolds number <1), symmetric and in-phase movements of micro-actuators would induce no net fluid flow. Therefore the generation of asymmetric or out-of-phase movements of microactuators has been investigated for each actuator concept. The interaction of magnetic particles embedded in PDMS has been studied and compared to the interactions in a ferrofluid. The enhancement of magnetic susceptibility due to the particle interactions was found to be limited because of the clustering of magnetic particles in the polymer that induces local demagnetisation. The alignment of clusters of particles in a magnetic field was investigated and the resulting magnetic anisotropy was quantified. Modelling has established that such an intrinsic magnetic anisotropy for an actuator can provide an increase in actuation amplitude up to one order of magnitude, for the same stimulus. The magnetic PDMS composites developed in this thesis have been used to fabricate high aspect ratio micro-actuators that are standing or lying on a substrate. Standing superparamagnetic PDMS micro-actuators were produced by mould replication. The standing micro-actuators have been actuated locally with the high magnetic field gradient generated by an integrated current wire (resulting in actuation by magnetic gradient force). The local stimulus allows for individual addressing of the micro-actuators and potentially enables out-of-phase movements of adjacent actuators. Possible geometries for the actuator device have been explored with models that describe the deffection of the actuators and the heat dissipation in the current wire. The fabricated micro-actuators were found to respond to the magnetic stimulus of the current wire but also to the thermal stimulus associated to the heat dissipation in the current wire, because of temperature dependent swelling of the micro-actuators in a solvent. The different time scales of magnetic and thermal actuation allowed the creation of an asymmetric movement. The standing micro-actuators have also been actuated by a homogeneous magnetic field generated by an external electromagnet (resulting in actuation by magnetic torque). A non-constant phase lag was demonstrated between actuators having different amplitudes of defection, which can potentially provide efficient mixing on small scales. The high frequency actuation of the standing micro-actuators was found to be limited to 5 Hz, which we attribute to the viscous behaviour of the PDMS. Lying ferromagnetic PDMS micro-actuators were produced with lithographic and sacrificial layer techniques. The lying micro-actuators have been actuated by a homogeneous magnetic field generated by an external electromagnet (resulting in actuation by magnetic torque). The permanent magnetisation of the actuators allowed for much larger deflections than for the standing superparamagnetic actuators. For a specific initial magnetisation of the actuators and using a rotating magnetic field, the actuators were shown to exhibit selectively either a symmetric or an asymmetric movement. The actuation at high frequencies of the microactuators was limited by the viscous drag in fluid and, in our experiments, by the high frequency limitations of the electromagnet. The micro-actuators could operate up to a frequency of 50 Hz, which is one order of magnitude higher than for the standing super paramagnetic actuators. The higher actuation frequency indicated that the type of PDMS used to fabricate the lying ferromagnetic micro-actuators exhibits less viscous behaviour. In a microfluidic cavity, the lying ferromagnetic micro-actuators induced local vortices or translational net fluid flows, depending on their initial magnetisation. Two micro-actuators pointing in opposite directions were actuated fully independently with the same external stimulus, depending on the rotation direction of the magnetic field. The different re-magnetisation in each case could explain the possibility for individual actuation. Provided with this independent actuation, two sets of vortices can be controlled individually in a microfluidic device, which is particularly promising to mix fluids with e.g: a blinking vortex protocol. The observed translational net fluid flows can in principle provide integrated pumping in microfluidic device

Fluorescent Probes and Labels for Cellular Imaging

Metal-responsive fluorescent indicators are powerful tools for visualizing trace metals with subcellular resolution. By taking advantage of the diverse photophysical properties of organic fluorophores, metal ion-selective fluorescent indicators have been rationally designed and tailored towards cellular applications. This review summarizes challenges associated with the probe design and describes recent efforts in our research group in developing selective and sensitive reagents for the detection of zinc and copper in mammalian cells

Quel avenir pour Airbnb en Suisse ?

Cette étude se focalise sur la définition, l'analyse et l'interprétation des facteurs et conséquences influents relatifs au développement de la plateforme Airbnb. Cette plateforme communautaire permet aux vacanciers de réserver et louer des logements entiers ou partagés à des particuliers. L'objectif de ce travail est non seulement de comprendre comment une start-up a réussi à concurrencer tout un domaine hôtelier en créant une communauté et en lançant un nouveau concept, mais surtout d'imaginer quels seront les futurs possibles de l'avenir d'Airbnb en Suisse à l'aide de la cartographie de l'information. Cette dernière a été réalisée grâce aux interviews de quinze différents répondants issus de divers domaines: touristique, hôtellerie, politique et journalisme, ayant chacun leur petite idée quant à l'évolution d'Airbnb en Suisse. Les deux cartographies ont été créées par M. Pierre-Alexandre Fonta, assistant de recherche, sur la base des données collectées auprès des répondants. C'est grâce à ces cartes que les principales tendances et dynamiques du développement d'Airbnb ont pu être ressorties afin d'établir six futurs scénarios provenant directement de l'imagination de cinq répondants et moi-même. Parmi ces six scénarios, un seul sera désigné comme le futur souhaitable d'Airbnb et des recommandations seront données afin de le mettre en application de façon optimale

Real Anaphora Resolution is Hard

We introduce a system for anaphora resolution for German that uses various resources in order to develop a real system as opposed to systems based on idealized assumptions, e.g. the use of true mentions only or perfect parse trees and perfect morphology. The components that we use to replace such idealizations comprise a full-fledged morphology, a Wikipedia-based named entity recognition, a rule-based dependency parser and a German wordnet. We show that under these conditions coreference resolution is (at least for German) still far from being perfect