La Déclaration de Doha sur la santé publique : la bonne prescription ? Une perspective historique sur le débat concernant la protection par brevet des médicaments

Le 14 mai 2005, les modifcations à la Loi sur les brevets du Canada sont entrées en vigueur. Ce changement a pour objet de permettre aux pays en voie de développement d’avoir accès à des médicaments génériques à moindre coût. Cette réforme met en oeuvre la Déclaration de Doha et la décision du 30 août 2003 du Conseil général de l’Organisation mondiale du commerce. Le présent article examine la pertinence de ces modifcations en les replaçant dans un contexte historique. Dans ce dessein, les auteurs retracent d’abord l’origine historique du brevet en insistant sur le domaine pharmaceutique. Ils démontrent ensuite en quoi l’Accord sur les aspects des droits de propriété intellectuelle qui touchent au commerce (ADPIC) constitue un renforcement du régime international de protection de la propriété industrielle pour enfn se demander si la solution adoptée à Doha puis au Canada est la bonne.On May 14, 005, the amendments to the Canada Patent Acttook effect. The purpose of the amendments is to make it possible for developing countries to have access to generic medicines at a lower cost. This reform implements the Doha Declaration and the August 30, 003 decision of the General Council of the World Trade Organization. This paper analyzes the relevance of these modifcations by situating them in their historic context. As such, the authors return to the historic origins of the patent by emphasizing developments in the pharmaceutical feld. They then illustrate the manner in which the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS Agreement) constitutes an intensifca-tion of the international system for protecting industrial ownership, then they fnally dwell upon righteousness of the solution adopted at Doha, then by Canada

Magneto-optical Kerr effect in Weyl semimetals with broken inversion and time-reversal symmetries

The topological nature of the band structure of a Weyl semimetal leads to a number of unique transport and optical properties. For example, the description of the propagation of an electromagnetic wave in a Weyl semimetal with broken time-reversal and inversion symmetry, for example, requires a modification of the Maxwell equations by the axion field $\theta \left( \mathbf{r},t\right) =2\mathbf{b}\cdot \mathbf{r}-2b_{0}t,$ where $2$ is the separation in wave vector space between two Weyl nodes of opposite chiralities and $2\hslash b_{0}$ is their separation in energy. In this paper, we study theoretically how the axion terms $b_{0}$ and $\bf{b}$ modify the frequency behavior of the Kerr rotation and ellipticity angles $\theta_{K}\left( \omega \right)$ and $\psi_{K}\left( \omega \right)$ in a Weyl semimetal. Both the Faraday and Voigt configurations are considered since they provide different information on the electronic transitions and plasmon excitation. We derive the Kerr angles firstly without an external magnetic field where the rotation of the polarization is only due to the axion terms and secondly in a strong magnetic field where these terms compete with the gyration effect of the magnetic field. In this latter case, we concentrate on the ultra-quantum limit where the Fermi level lies in the chiral Landau level and the Kerr and ellipticity angles have more complex frequency and magnetic field behaviors.Comment: 21 pages with 14 PDF figure

Chiral filtration and Faraday rotation in multi-Weyl semimetals

In Weyl semimetals with broken inversion and time-reversal symmetries, the Maxwell equations are modified by the presence of the axion terms $\mathbf{b}$ and $b_{0}$ where, in the simplest case of a two-node Weyl semimetal, $2\hslash \mathbf{b}$ is the vector that connects two Weyl nodes in momentum space and $2\hslash b_{0}$ is the separation in energy of the two Dirac points of these nodes. These axion terms modify the behavior of electromagnetic waves inside a Weyl semimetal leading to a number of unique optical properties such as non-reciprocal propagation, circular and linear dichroism, birefringence and Faraday and Kerr rotations in the absence of a magnetic field. These effects can be used to design optical devices that act as broadband chiral filters, circular polarizers or tunable optical isolators. In this paper, we study in detail how the Faraday and Kerr rotations as well as the transmission and reflection of light incident on a slab of Weyl semimetal can be controlled by varying the different parameters characterizing the Weyl semimetal such as the axion terms, the Fermi level and Fermi velocity, the background dielectric constant, the scattering time for intraband scattering, the width of the semimetal and the dielectric constant of the dielectrics on each side of the semimetal slab. We extend our analysis to Weyl nodes with Chern number $n=1,2,3$.Comment: 18 pages, 14 figure

Detecting changes in the annual movements of terrestrial migratory species : using the first-passage time to document the spring migration of caribou

Background : Migratory species face numerous threats related to human encroachment and climate change. Several migratory populations are declining and individuals are losing their migratory behaviour. To understand how habitat loss or changes in the phenology of natural processes affect migrations, it is crucial to clearly identify the timing and the patterns of migration. We propose an objective method, based on the detection of changes in movement patterns, to identify departure and arrival dates of the migration. We tested the efficiency of our approach using simulated paths before applying it to spring migration of migratory caribou from the Rivière-George and Rivière-aux-Feuilles herds in northern Québec and Labrador. We applied the First-Passage Time analysis (FPT) to locations of 402 females collected between 1986 and 2012 to characterize their movements throughout the year. We then applied a signal segmentation process in order to segment the path of FPT values into homogeneous bouts to discriminate migration from seasonal range use. This segmentation process was used to detect the winter break and the calving ground use because spring migration is defined by the departure from the winter range and the arrival on the calving ground. Results : Segmentation of the simulated paths was successful in 96% of the cases, and had a high precision (96.4% of the locations assigned to the appropriate segment). Among the 813 winter breaks and 669 calving ground use expected to be detected on the FPT profiles, and assuming that individuals always reduced movements for each of the two periods, we detected 100% of the expected winter breaks and 89% of the expected calving ground use, and identified 648 complete spring migrations. Failures to segment winter breaks or calving ground use were related to individuals only slowing down or performing less pronounced pauses resulting in low mean FPT. Conclusion : We show that our approach, which relies only on the analysis of movement patterns, provides a suitable and easy-to-use tool to study species exhibiting variations in their migration patterns and seasonal range use

Microtubule disrupting N-phenyl-N’-(2-chloroethyl) ureas display anticancer activity on cell adhesion, P-glycoprotein and BCL-2-mediated drug resistance

Objective: Our research program has focused on the development of promising, soft alkylating N-phenyl-N’-(2-chloroethyl)urea (CEU) compounds which acylate the glutamic acid-198 of β-tubulin, near the binding site of colchicum alkaloids. CEUs inhibit the motility of cancerous cells in vitro and, interestingly, exhibit antiangiogenic and anticancer activity in vivo. Mitotic arrest induced by microtubule-interfering agents such as CEUs remains the major mechanism of their anticancer activity, leading to apoptosis. However, we recently demonstrated that microtubule disruption by CEUs and other common antimicrotubule agents greatly alters the integrity and organization of microtubule-associated structures, the focal adhesion contact, thereby initiating anoikis, an apoptosis-like cell death mechanism caused by the loss of cell contact with the extracellular matrix. Methods: To ascertain the activated signaling pathway profile of CEUs, flow cytometry, Western blot, immunohistochemistry and transfection experiments were performed. Wound-healing and chick embryo assays were carried out to evaluate the antiangiogenic potency of CEUs. Results: CEU-induced apoptosis involved early cell cycle arrest in G2/M and increased level of CDK1/cycline B proteins. These signaling events were followed by the specific activation of the intrinsic apoptosis pathway, involving loss of mitochondrial membrane potential (Δψm) and ROS production, cytochrome c release from mitochondria, caspase activation, AIF nuclear translocation, PARP cleavage and nuclear fragmentation. CEUs maintained their efficacy on cells plated on pro-survival extracellular matrices or exhibiting overexpression of P-glycoprotein or the anti-apoptotic protein Bcl-2. Conclusion: Our results suggest that CEUs represent a promising new class of antimicrotubule, antiangiogenic and pro-anoikis agents