Dynamical Coulomb Blockade Observed in Nano-Sized Electrical Contacts

Electrical contacts between nano-engineered systems are expected to constitute the basic building blocks of future nano-scale electronics. However, the accurate characterization and understanding of electrical contacts at the nano-scale is an experimentally challenging task. Here we employ low-temperature scanning tunneling spectroscopy to investigate the conductance of individual nano-contacts formed between flat Pb islands and their supporting substrates. We observe a suppression of the differential tunnel conductance at small bias voltages due to dynamical Coulomb blockade effects. The differential conductance spectra allow us to determine the capacitances and resistances of the electrical contacts which depend systematically on the island--substrate contact area. Calculations based on the theory of environmentally assisted tunneling agree well with the measurements.Comment: 5 pages, 3 figures, to appear in PR

The Brown Algal Virus EsV-1 Particle Contains a Putative Hybrid Histidine Kinase

AbstractThe Ectocarpus siliculosus virus, EsV-1, occurs worldwide in all populations of the filamentous marine brown alga E. siliculosus. We have screened an expression library of EsV-1 restriction fragments and identified a DNA clone with the potential to code for a 52-kDa histidine protein kinase. The derived amino acid sequence includes all homology boxes diagnostic for histidine protein kinases and, in addition, amino acid motifs that are commonly found in response regulators of bacterial two-component signal transduction proteins. Thus, the novel viral protein can be classified as a hybrid histidine protein kinase of a type that has previously been detected in fungi, slime molds, and plants. By using purified antibodies, we found that the protein with its potential kinase activity is located on the outer shell of viral particles. This is the first report on a two-component regulator-like protein in viruses and could provide the basis for speculations with regard to the evolution of EsV-1 and related viruses

Die archäologisch-topographische Vermessung des Mont Lassois bei Châtillon sur Seine, Côte d’Or, in den Jahren 2002 - 2005 - Methoden und Ergebnisse

Die in das "Projet Collectif de Recherche: Vix et son Environnement" (PCR Vix) eingebundene topographische Vermessung des Mont Lassois begann im Frühjahr 2002. Sie soll einen Grundlagenplan für die archäologische Erforschung des Berges liefern

European Perspectives for Electron-Nucleon Scattering at the Luminosity Frontier

European perspectives are discussed on fixed-target electron or positron scattering experiments using polarized and unpolarized beams and targets in various combinations. The goal envisioned is a deep and complete understanding of the momentum and spin structure of hadrons in the context of Quantum Chromo Dynamics, based on measurements at moderate and low photon virtualities. This program can be realized by performing electron-nucleon experiments with high resolution and high luminosity, at beam energies of at least 25-30 GeV.Comment: 7 pages, 6 figures, Invited talk at the Workshop `The Spin Structure of the Proton and Polarized Collider Physics', Trento/Italy, July 23-28, 2001; to appear in Nuclear Physics B (proc suppl

Pattern analysis of gap junction plaques with open and closed pores

The structure of freeze-fractured gap junctions was studied by electron microscopy and subsequent pattern analysis using a computer controlled image processing system. Rat mammary tumor cells (BICR/WIR-k) which are permanently coupled via gap junctions when cultered as monolayers were used under different fixed and unfixed conditions. Active (coupling competent) gap junctions seem to be characterized by loosely packed connexons, whereas non-active (permanently closed) gap junctions may consist of tightly packed particles

Magnesium and its alloys as degradable biomaterials : Corrosion studies using potentiodynamic and EIS electrochemical techniques

Magnesium is potentially useful for orthopaedic and cardiovascular applications. However, the corrosion rate of this metal is so high that its degradation occurs before the end of the healing process. In industrial media the behaviour of several magnesium alloys have been probed to be better than magnesium performance. However, the information related to their corrosion behaviour in biological media is insufficient. The aim of this work is to study the influence of the components of organic fluids on the corrosion behaviour of Mg and AZ31 and LAE442 alloys using potentiodynamic, potentiostatic and EIS techniques. Results showed localized attack in chloride containing media. The breakdown potential decreased when chloride concentration increased. The potential range of the passivation region was extended in the presence of albumin. EIS measurements showed that the corrosion behaviour of the AZ31 was very different from that of LAE442 alloy in chloride solutions.Facultad de Ciencias Exacta

Особенности оценки профессиональных рисков в медицинской организации

Работа посвящена оценки профессионального риска для работников медицинских организаций с учетом эпидемиологической обстановки. В данной работе рассмотрено нормативно-правовое регулирование оценки профессионального риска в Российской Федерации. Проведен анализ существующих методов оценки профессионального риска. В результате исследования проведена оценка профессионального риска для работников медицинской организации и предложены мероприятия по уменьшению уровня риска.The work is devoted to the assessment of professional risk for employees of medical organizations, taking into account the epidemiological situation. This paper examines the legal regulation of professional risk assessment in the Russian Federation. The analysis of existing methods of professional risk assessment is carried out. As a result of the study, an assessment of professional risk for employees of a medical organization was carried out and measures to reduce the level of risk were proposed

Unveiling the Role of Metal Ion Concentration versus Immune Sensitization in Orthodontic Patients-A Long-Term Prospective Evaluation.

Background: This longitudinal prospective study aimed to assess orthodontic patients' immune system response to metal ion release in saliva. Methods: Thirty adult patients (18-35 years) were equally divided into three groups: groups at the end (G1) and beginning (G2) of multibracket appliances (MBA) treatment and a non-treated control group (G3). Participants were evaluated at four timepoints within 21 days, with saliva samples being analyzed for metal ion concentrations and blood for the lymphocyte transformation test (LTT). Results: There were no significant differences between groups or timepoints for saliva. LTT analyses revealed hypersensitivity in one-third of all patients and 50% of G2 for nickel, with three developing sensitizations after MBA insertion. All nickel-sensitized patients exhibited varying elevated saliva nickel concentrations. The most nickel-sensitized patients had low ion saliva loads. In borderline nickel-sensitization cases, saliva ion concentrations were up to 20 times higher than the reference. Hypersensitivity to palladium, gold, and mercury was also observed. Conclusions: These findings indicate that increased MBA ion release was not inherently linked to the immune response (Type-IV sensitization), as reactions occurred even with ion levels below thresholds. This underlines the need for a comprehensive evaluation of the immune response to metal ion release in orthodontic patients

Исследование последовательности импульсов тормозного излучения малогабаритного бетатрона

Разработана имитационная модель потока импульсного тормозного излучения и реализована в подпрограмме на MathCad. Адаптирована модель потока импульсного тормозного излучения к имитационной модели формирования цифровых радиографических изображений. Исследовано влияние параметров исходного потока тормозного излучения на качество цифровых радиографических изображений. Проведён цикл натурных экспериментов по оценке изменения параметров потока импульсов регистрируемого излучения с цифровых детекторов на этапах формирования радиографического изображения на комплексе высокоэнергетической цифровой радиографии Томского политехнического университета.A simulation model of pulsed radiation flux and implemented in a subroutine on MathCad is available. Pulse bremsstrahlung flow model for a simulation model of digital radiographic image formation Adapted. Effect of source stream parameters. Experiments on the study of changes in the parameters of the pulse flux are recorded using digital detectors at the stages of radiographic image formation on the complexes of high-energy digital radiography of the Tomsk Polytechnic University

Integrated Techno-Economic Power System Planning of Transmission and Distribution Grids

The energy transition towards renewable and more distributed power production triggers the need for grid and storage expansion on all voltage levels. Today’s power system planning focuses on certain voltage levels or spatial resolutions. In this work we present an open source software tool eGo which is able to optimize grid and storage expansion throughout all voltage levels in a developed top-down approach. Operation and investment costs are minimized by applying a multi-period linear optimal power flow considering the grid infrastructure of the extra-high and high-voltage (380 to 110 kV) level. Hence, the common differentiation of transmission and distribution grid is partly dissolved, integrating the high-voltage level into the optimization problem. Consecutively, optimized curtailment and storage units are allocated in the medium voltage grid in order to lower medium and low voltage grid expansion needs, that are consequently determined. Here, heuristic optimization methods using the non-linear power flow were developed. Applying the tool on future scenarios we derived cost-efficient grid and storage expansion for all voltage levels in Germany. Due to the integrated approach, storage expansion and curtailment can significantly lower grid expansion costs in medium and low voltage grids and at the same time serve the optimal functioning of the overall system. Nevertheless, the cost-reducing effect for the whole of Germany was marginal. Instead, the consideration of realistic, spatially differentiated time series led to substantial overall savings