Enhanced radiation hardness of quantum dot lasers to high energyproton irradiation

The influence of high energy proton irradiation on the device properties of InGaAs/GaAs quantum dot and quantum well lasers has been investigated. In the regime of spontaneous emission, quantum dot lasers show a much enhanced radiation hardness compared to quantum well lasers, manifested in a smaller increase of threshold current density. However, in the lasing regime the device characteristics are similarly influenced. Internal differential quantum efficiencies are reduced, internal optical losses remain constant     

Restructuring of Swiss parcel delivery services

Abstract. Recently, the Swiss postal services has been confronted with some drastic changes. First, the areas of telecommunication and postal services were divided into two independent enterprises, and secondly, the market for postal services in Switzerland was deregulated to a large extent. These developments forced the public PTT not only to change its organisational structure but also its logistics system. In the new system the customers will be mainly served by transshipment points. A main problem was to decide on the number, the locations, the sizes, and service areas of these transshipment points. The decision was supported by means of a discrete facility location model. This paper discusses the location problem and the used solution approach. An emphasis is given on the determination of the cost parameters.     

Comparative analysis of related notions of opacity in centralized and coordinated architectures

Opacity is a confidentiality property that captures whether an intruder can infer a “secret” of a system based on its observation of the system behavior and its knowledge of the system’s structure. In this paper, we study four notions of opacity: language-based opacity, initial-state opacity, current-state opacity, and initial-and-final-state opacity. Initial-and-final-state opacity is a new opacity property introduced in this paper, motivated by secrecy considerations in anonymous network communications; the other three opacity properties have been studied in prior work. We investigate the relationships between these opacity properties. In this regard, a complete set of transformation algorithms among the four notions is provided. We also propose a new, more efficient test for initial-state opacity based on the use of reversed automata, and present a trellis-based test for the new property of initial-and-final state opacity. We then study the notions of initial-state opacity, current-state opacity, and initial-and-final-state opacity in the context of a new coordinated architecture where two intruders work as a team in order to infer the secret. In this architecture, the intruders have the capability of combining their respective state estimates at a coordinating node. In each case, a characterization of the corresponding notion of “joint opacity” and an algorithmic procedure for its verification are provided.     

Influence of closure on the 3D propagation of fatigue cracks in a nodular cast iron investigated by X-ray tomography and 3D volume correlation

Synchrotron X-ray tomography was performed during in situ fatigue crack propagation in two small-size specimens made of nodular graphite cast iron. While direct image analysis allows us to retrieve the successive positions of the crack front, and to detect local crack retardation, volume correlation allows for the measurement of displacement fields in the bulk of the specimen. The stress intensity factors (SIFs), which are extracted from the measured displacement fields and the corresponding local crack growth rate all along the front, are in good agreement with published results. In particular, it is possible to link the non-propagation of a crack with crack closure in the crack opening displacement maps or with a local value of the measured SIF range. It is shown that a non-uniform closure process along the crack front induces an asymmetric arrest/growth of the crack.     

Review of Les troubles anxieux: Approche cognitive et comportementale.

Reviews the book, Les troubles anxieux: Approche cognitive et comportementale by Robert Ladouceur, André Marchand, and Jean-Marie Boisvert (1999). This volume offers an excellent source of information for private practitioners, students, and trainees. After a brief introduction, each chapter describes a particular anxiety disorder and explores the following topics: DSM-IV diagnosis, prevalence and comorbidity, major elements of differential diagnosis, evaluation and instrumental measures, intervention strategies, and future research. Case studies are included. The authors clearly transmit current scientific knowledge on anxiety disorders and therapeutic applications. The cognitive behavioral approach integrates therapeutic strategies with demonstrated effectiveness. Therefore, this book is impossible to circumvent. Any professional who is interested in anxiety disorders should read and re-read this volume. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Single‐Molecule Imaging Reveals that Small Amyloid‐β1–42 Oligomers Interact with the Cellular Prion Protein (PrPC)

Oligomers of the amyloid‐β peptide (Aβ) play a central role in the pathogenesis of Alzheimer’s disease and have been suggested to induce neurotoxicity by binding to a plethora of cell‐surface receptors. However, the heterogeneous mixtures of oligomers of varying sizes and conformations formed by Aβ42 have obscured the nature of the oligomeric species that bind to a given receptor. Here, we have used single‐molecule imaging to characterize Aβ42 oligomers (oAβ42) and to confirm the controversial interaction of oAβ42 with the cellular prion protein (PrP^C) on live neuronal cells. Our results show that, at nanomolar concentrations, oAβ42 interacts with PrP^C and that the species bound to PrP^C are predominantly small oligomers (dimers and trimers). Single‐molecule biophysical studies can thus aid in deciphering the mechanisms that underlie receptor‐mediated oAβ‐induced neurotoxicity, and ultimately facilitate the discovery of novel inhibitors of these pathways.     

Identification of Novel CERT Ligands as Potential Ceramide Trafficking Inhibitors

A highly compartmentalized enzymatic network regulates the pro‐apoptotic and proliferative effects of sphingolipids. Over‐conversion of ceramide (Cer) correlates with insensitivity to apoptosis signaling (in response to chemotherapy) and to drug resistance of cancer cells. De novo sphingomyelin biosynthesis relies on non‐vesicular ceramide trafficking by the CERT (CERamide Transfer) protein. Therefore, blocking CERT transfer, thus leading to increased intracellular ceramide availability, represents a potential anticancer strategy. Our study is based on the implementation of an in vitro binding assay, supported by in silico molecular docking. It constitutes the first attempt to explore at the molecular level for the identification of novel CERT ligands. This approach is the first step toward in silico design and optimization of CERT inhibitor candidates, potentially relevant as innovative ceramide‐transfer‐targeting therapeutic agents.     

Microstructure Evolution and Cation Interdiffusion in Thin Sm2O3 Films on CeO2 Substrates

Samaria (Sm₂O₃) thin films with a thickness of 180 nm were deposited on polycrystalline CeO₂ substrates by pulsed layer deposition to study phase formation and bulk cation interdiffusion in the Ce_1?xSm_xO_2?x/2 system after annealing at temperatures between 987°C and 1266°C. Transmission electron microscopy combined with electron diffraction and analytical techniques was applied for phase determination. The cubic fluorite and cubic bixbyite phases were observed at low and intermediate Sm concentrations. The monoclinic phase occurs only at very high Sm concentrations due to the low Ce‐solubility in Sm₂O₃. Furthermore, a cubic phase with I2₁3 structure was observed at higher Sm concentrations. Cation interdiffusion coefficients were derived from Sm concentration profiles across the Sm₂O₃/CeO₂ interface using the diffusion–couple solution of the diffusion equation. The temperature dependence of interdiffusion coefficients is well described by an Arrhenius‐type relation, which yields an activation enthalpy of 2.26 eV/atom for bulk cation interdiffusion.