Schottky barrier heights at polar metal/semiconductor interfaces

Using a first-principle pseudopotential approach, we have investigated the Schottky barrier heights of abrupt Al/Ge, Al/GaAs, Al/AlAs, and Al/ZnSe (100) junctions, and their dependence on the semiconductor chemical composition and surface termination. A model based on linear-response theory is developed, which provides a simple, yet accurate description of the barrier-height variations with the chemical composition of the semiconductor. The larger barrier values found for the anion- than for the cation-terminated surfaces are explained in terms of the screened charge of the polar semiconductor surface and its image charge at the metal surface. Atomic scale computations show how the classical image charge concept, valid for charges placed at large distances from the metal, extends to distances shorter than the decay length of the metal-induced-gap states.Comment: REVTeX 4, 11 pages, 6 EPS figure

Pathways to collaborative performance: examining the different combinations of conditions under which collaborations are successful

The literature on collaborative governance has generated several comprehensive models detailing the conditions which collaborations must meet to achieve collaborative performance. The importance of each separate condition – such as the presence of incentives to participate, appropriate institutional designs, or facilitative leadership – has been validated in various studies. How all of these conditions interact with each other, and whether all of the conditions need to be present to achieve performance, is less well understood. Leveraging the rich resource of the newly created Collaborative Governance Case Database, this article explores the different pathways to performance used by 26 local collaborations. The analysis shows that the presence of strong incentives for partners to collaborate is a crucial condition for success; almost all performing cases shared this starting point. Performance was then achieved by combining strong incentives with either clear institutional design (e.g. explicit rules, transparent decision-making) or with intensive collaborative processes (e.g. face-to-face dialogue, knowledge sharing). This analysis shows that the current models for collaborative governance can serve as roadmaps, laying out all of the different conditions than may be important, but that collaborations can follow different routes to reach their objectives

Bone mineral density in breast cancer patients treated with adjuvant letrozole, tamoxifen, or sequences of letrozole and tamoxifen in the BIG 1-98 study (SAKK 21/07)

Background: The risk of osteoporosis and fracture influences the selection of adjuvant endocrine therapy. We analyzed bone mineral density (BMD) in Swiss patients of the Breast International Group (BIG) 1-98 trial [treatment arms: A, tamoxifen (T) for 5 years; B, letrozole (L) for 5 years; C, 2 years of T followed by 3 years of L; D, 2 years of L followed by 3 years of T]. Patients and methods: Dual-energy X-ray absorptiometry (DXA) results were retrospectively collected. Patients without DXA served as control group. Repeated measures models using covariance structures allowing for different times between DXA were used to estimate changes in BMD. Prospectively defined covariates were considered as fixed effects in the multivariable models. Results: Two hundred and sixty-one of 546 patients had one or more DXA with 577 lumbar and 550 hip measurements. Weight, height, prior hormone replacement therapy, and hysterectomy were positively correlated with BMD; the correlation was negative for letrozole arms (B/C/D versus A), known osteoporosis, time on trial, age, chemotherapy, and smoking. Treatment did not influence the occurrence of osteoporosis (T score < −2.5 standard deviation). Conclusions: All aromatase inhibitor regimens reduced BMD. The sequential schedules were as detrimental for bone density as L monotherap

QED3 theory of pairing pseudogap in cuprates: From d-wave superconductor to antiferromagnet via "algebraic" Fermi liquid

High-$T_c$ cuprates differ from conventional superconductors in three crucial aspects: the superconducting state descends from a strongly correlated Mott-Hubbard insulator, the order parameter exhibits d-wave symmetry and superconducting fluctuations play an all important role. We formulate a theory of the pseudogap state in the cuprates by taking the advantage of these unusual features. The effective low energy theory within the pseudogap phase is shown to be equivalent to the (anisotropic) quantum electrodynamics in (2+1) space-time dimensions (QED$_3$). The role of Dirac fermions is played by the nodal BdG quasiparticles while the massless gauge field arises through unbinding of quantum vortex-antivortex degrees of freedom. A detailed derivation of this QED$_3$ theory is given and some of its main physical consequences are inferred for the pseudogap state. We focus on the properties of symmetric QED$_3$ and propose that inside the pairing protectorate it assumes the role reminiscent of that played by the Fermi liquid theory in conventional metals.Comment: 31 pages, 4 figures; replaced with revised versio

Dynamic Interferometry Lithography on a TiO 2

International audienceSolar electricity is one of the most promising renewable energy resources. However, the ratio module's cost/energy produced remains a major issue for classical photovoltaic energy. Many technologies have been developed to solve this problem, by using micro-or nanostructuring on the solar cell or on the module. These kinds of structuring are often used as antireflection and light-trapping tools. In the meantime, other solar technologies are considered, such as concentration photovoltaic modules. This article presents a module combining both approaches, that is, nanostructures and concentration, in order to increase the module's profitability. Sol-gel derived TiO 2 diffraction gratings, made by dynamic interferometric lithography, are added on the top of the glass cover to deflect unused light onto the solar cell, increasing the module efficiency

Vaccination with LAG-3Ig (IMP321) and Peptides Induces Specific CD4 and CD8 T-Cell Responses in Metastatic Melanoma Patients-Report of a Phase I/IIa Clinical Trial.

PURPOSE: Cancer vaccines aim to generate and maintain antitumor immune responses. We designed a phase I/IIa clinical trial to test a vaccine formulation composed of Montanide ISA-51 (Incomplete Freund's Adjuvant), LAG-3Ig (IMP321, a non-Toll like Receptor agonist with adjuvant properties), and five synthetic peptides derived from tumor-associated antigens (four short 9/10-mers targeting CD8 T-cells, and one longer 15-mer targeting CD4 T-cells). Primary endpoints were safety and T-cell responses. EXPERIMENTAL DESIGN: Sixteen metastatic melanoma patients received serial vaccinations. Up to nine injections were subcutaneously administered in three cycles, each with three vaccinations every 3 weeks, with 6 to 14 weeks interval between cycles. Blood samples were collected at baseline, 1-week after the third, sixth and ninth vaccination, and 6 months after the last vaccination. Circulating T-cells were monitored by tetramer staining directly ex vivo, and by combinatorial tetramer and cytokine staining on in vitro stimulated cells. RESULTS: Side effects were mild to moderate, comparable to vaccines with Montanide alone. Specific CD8 T-cell responses to at least one peptide formulated in the vaccine preparation were found in 13 of 16 patients. However, two of the four short peptides of the vaccine formulation did not elicit CD8 T-cell responses. Specific CD4 T-cell responses were found in all 16 patients. CONCLUSIONS: We conclude that vaccination with IMP321 is a promising and safe strategy for inducing sustained immune responses, encouraging further development for cancer vaccines as components of combination therapies. Clin Cancer Res; 22(6); 1330-40. ©2015 AACR

Myiases d’ici et d’ailleurs : pseudo-furonculose et bactériémie à Ignatzschineria larvae [Myases from here and elsewhere : pseudo-furonculosis and Ignatzschineria larvae bacteremia]

Myiasis is an infestation by maggots. In humans, it predominates in regions with low socio-economic development. We report on two cases of myiasis acquired during a tropical travel and in Switzerland, respectively. The first one presented as a furunculous-like disease due to the invasion of subcutaneous tissues by Cordylobia sp. larvae. The second corresponded to a chronic wound infestation that resulted in a rarely reported bacteremia due to Ignatzschineria larvae, a commensal bacteria of maggots' digestive tract. Surgery was necessary in both cases, mainly for psychological reasons in the first case. Both the entomologist and molecular biology were instrumental for treatment decisions

Counter-current chromatography for the separation of terpenoids: A comprehensive review with respect to the solvent systems employed

Copyright @ 2014 The Authors.This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid-solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids-one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications. © 2014 The Author(s)

Hazardous explosive eruptions of a recharging multi-cyclic island arc caldera

Caldera-forming eruptions of silicic volcanic systems are among the most devastating events on Earth. By contrast, post-collapse volcanic activity initiating new caldera cycles is generally considered less hazardous. Formed after Santorini’s latest caldera-forming eruption of ~1600 bce, the Kameni Volcano in the southern Aegean Sea enables the eruptive evolution of a recharging multi-cyclic caldera to be reconstructed. Santorini’s eruptive record has been documented by onshore products and historical descriptions of mainly effusive eruptions dating back to 197 bce. Here we combine high-resolution seismic reflection data with cored lithologies from International Ocean Discovery Program Expedition 398 at four sites to determine the submarine architecture and volcanic history of intra-caldera deposits from Kameni. Our shore-crossing analysis reveals the deposits of a submarine explosive eruption that produced up to 3.1 km3 of pumice and ash, which we relate to a historical eruption in 726 ce. The estimated volcanic explosivity index of magnitude 5 exceeds previously considered worst-case eruptive scenarios for Santorini. Our finding that the Santorini caldera is capable of producing large explosive eruptions at an early stage in the caldera cycle implies an elevated hazard potential for the eastern Mediterranean region, and potentially for other recharging silicic calderas

Modeling scanning tunneling spectra of Bi2Sr2CaCu2O8+δBi_2 Sr_2 CaCu_2 O_{8+\delta}

Recent angle-resolved photoemission and neutron scattering data have provided new ingredients for the interpretation of scanning tunneling spectra on Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. We analyze the low-temperature tunneling spectra, from oxygen overdoped to underdoped samples, including details about the bilayer splitting and the neutron resonance peak. Two van Hove singularities are identified: the first is integrated in the coherence peaks, the second is heavily broadened at higher binding energy. The shape of the tunneling spectra suggests a strong coupling of the quasiparticles with a collective mode, and a comparison with photoemission shows that the scattering rate in tunneling is an order of magnitude smaller than in ARPES. Finally, the theoretical spectra calculated with an isotropic tunneling matrix element are in better agreement with the experimental data than those obtained with anisotropic matrix elements.Comment: 7 pages, with 4 figure