Avant-propos

Résumé  37-2,167-86 Jørn Boisen: L'objectif de la présente étude est d'isoler un problème fondamental de l'esthétique et de la pensée de Kundera, à savoir comment explorer des thèmes philosophiques par des moyens romanesques ? Le soupçon du roman à thèse plane sur chaque roman qui contient une forte présence du penser. Pour réfuter cette accusation, le texte tente de dégager la relation très spécifique entre certaines propositions nietzschéennes, explicitement présentées et discutées dans L'insoutenable légèreté de l'être, et le destin d'un des personnages, la serveuse Térésa. L'analyse montre que le roman pensé de Kundera ne devient ni une défense ni une illustration des thèses philosophiques préétablies mais, au contraire, une exploration ambiguë et paradoxale de ce que deviennent les thèmes philosophiques dans « le monde de la vie »

Spatial and Temporal Assessment of Vertically Migrating Myctophids as Biotransporters of Microplastics to Mesopelagic Food Webs

It is well documented that microplastics and semi-synthetic particles (<5 mm) pervade the marine environment, with their ingestion by marine fauna eliciting global concern. While fishes exposed to microparticles in a laboratory setting have exhibited both sub-lethal and lethal effects, the diversity in material, morphology, and size of these contaminants in the ocean make it challenging to pinpoint the risks to wild organisms. Highly abundant, vertically-migrating myctophids play a crucial role in nutrient cycling between the epi- and mesopelagic zones, but may also serve as significant conduits for dispersing surface microparticles throughout the food web. Here, I examined the digestive tracts of newly-caught and museum-archived myctophids from the Northern California Current to determine (a) if myctophids caught closer to a presumed point source (i.e., Columbia River mouth) ingest more microplastics, and (b) if microplastic ingestion has increased over time. There was no relationship between microplastic consumption and distance from the river mouth or differences between the stations. However, body depth (a proxy for size) and water temperature exhibited a significant, positive association in the best-fit model. Overall, the number of suspected microplastics extracted from the museum specimens did not indicate an increasing trend over the compiled time series but a detailed analysis by geographic region identified a positive temporal microplastics presence trend in those myctophids captured near the continental United States. Approximately 30% of all specimens analyzed contained microparticles (~21% synthetic and ~79% anthropogenically modified), suggesting that myctophids are likely multidirectional transporters of these particles in Northern California Current food webs, with potential impacts on fisheries and human food systems. Exploring the spatial drivers and temporal trends of microplastic ingestion by mesopelagic fishes can help predict future vulnerability and direct efforts to reduce further contamination

Microfabricated photoplastic cantilever with integrated photoplastic/carbon based piezoresistive strain sensor

L. Gammelgaard, P. A. Rasmussen, M. Calleja, P. Vettiger, and A. Boisen Department of Micro- and Nanotechnology, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark We present an SU-8 micrometer sized cantilever strain sensor with an integrated piezoresistor made of a conductive composite of SU-8 polymer and carbon black particles. The composite has been developed using ultrasonic mixing. Cleanroom processing of the polymer composite has been investigated and it has been shown that it is possible to pattern the composite by standard UV photolithography. The composite material has been integrated into an SU-8 microcantilever and the polymer composite has been demonstrated to be piezoresistive with gauge factors around 15–20. Since SU-8 is much softer than silicon and the gauge factor of the composite material is relatively high, this polymer based strain sensor is more sensitive than a similar silicon based cantilever sensor.Peer reviewe

Present and future of surface-enhanced Raman scattering

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article

Orientation of Pterin-6-Carboxylic Acid on Gold Capped Silicon Nanopillars Platforms: Surface Enhanced Raman Spectroscopy and Density Functional Theory Studies

The orientation of pterin-6-carboxylic acid on gold nanopillars was investigated by surface enhanced Raman spectroscopy and density functional theory methods. The experimentally vibrations from pterin-6-COOH free and attached to the Au surface display vibration features indicating chemical interaction of the pterin with the metal surface. The spectral feature evidenced that the pterin would adsorb on gold surface with a "lying down" configuration through the high intensity vibration of NH scissoring and rocking OH modes. The orientation study of pterins on gold nanopillars presented herein is believed to lead to new applications in biosensing field for detecting pterins of physiological importance

Field-induced breakdown of the quantum Hall effect

A numerical analysis is made of the breakdown of the quantum Hall effect caused by the Hall electric field in competition with disorder. It turns out that in the regime of dense impurities, in particular, the number of localized states decreases exponentially with the Hall field, with its dependence on the magnetic and electric field summarized in a simple scaling law. The physical picture underlying the scaling law is clarified. This intra-subband process, the competition of the Hall field with disorder, leads to critical breakdown fields of magnitude of a few hundred V/cm, consistent with observations, and accounts for their magnetic-field dependence \propto B^{3/2} observed experimentally. Some testable consequences of the scaling law are discussed.Comment: 7 pages, Revtex, 3 figures, to appear in Phys. Rev.