Dual Maxwellian-Kappa modelling of the solar wind electrons: new clues on the temperature of Kappa populations

Context. Recent studies on Kappa distribution functions invoked in space plasma applications have emphasized two alternative approaches which may assume the temperature parameter either dependent or independent of the power-index $\kappa$. Each of them can obtain justification in different scenarios involving Kappa-distributed plasmas, but direct evidences supporting any of these two alternatives with measurements from laboratory or natural plasmas are not available yet. Aims. This paper aims to provide more facts on this intriguing issue from direct fitting measurements of suprathermal electron populations present in the solar wind, as well as from their destabilizing effects predicted by these two alternating approaches. Methods. Two fitting models are contrasted, namely, the global Kappa and the dual Maxwellian-Kappa models, which are currently invoked in theory and observations. The destabilizing effects of suprathermal electrons are characterized on the basis of a kinetic approach which accounts for the microscopic details of the velocity distribution. Results. In order to be relevant, the model is chosen to accurately reproduce the observed distributions and this is achieved by a dual Maxwellian-Kappa distribution function. A statistical survey indicates a $\kappa$-dependent temperature of the suprathermal (halo) electrons for any heliocentric distance. Only for this approach the instabilities driven by the temperature anisotropy are found to be systematically stimulated by the abundance of suprathermal populations, i.e., lowering the values of $\kappa$-index.Comment: Submitted to A&

Random walks in a random environment on a strip: a renormalization group approach

We present a real space renormalization group scheme for the problem of random walks in a random environment on a strip, which includes one-dimensional random walk in random environment with bounded non-nearest-neighbor jumps. We show that the model renormalizes to an effective one-dimensional random walk problem with nearest-neighbor jumps and conclude that Sinai scaling is valid in the recurrent case, while in the sub-linear transient phase, the displacement grows as a power of the time.Comment: 9 page

Review and extension of suitability assessment indicators of weather model output for analyzing decentralized energy systems

Electricity from renewable energy sources (RES-E) is gaining more and more influence in traditional energy and electricity markets in Europe and around the world. When modeling RES-E feed-in on a high temporal and spatial resolution, energy systems analysts frequently use data generated by numerical weather models as input since there is no spatial inclusive and comprehensive measurement data available. However, the suitability of such model data depends on the research questions at hand and should be inspected individually. This paper focuses on new methodologies to carry out a performance evaluation of solar irradiation data provided by a numerical weather model when investigating photovoltaic feed-in and effects on the electricity grid. Suitable approaches of time series analysis are researched from literature and applied to both model and measurement data. The findings and limits of these approaches are illustrated and a new set of validation indicators is presented. These novel indicators complement the assessment by measuring relevant key figures in energy systems analysis: e.g., gradients in energy supply, maximum values and volatility. Thus, the results of this paper contribute to the scientific community of energy systems analysts and researchers who aim at modeling RES-E feed-in on a high temporal and spatial resolution using weather model data. © 2015 by the authors

Li+ intercalation in isostructural Li2VO3 and Li2VO2 with O2- and mixed O2-/F- anions

Mixed-anion materials for Li-ion batteries have been attracting attention in view of their tunable electrochemical properties. Herein, we compare two isostructural (Fm3m) model intercalation materials Li2VO3 and Li2VO2F with O2- and mixed O2-/F- anions, respectively. Synchrotron X-ray diffraction and pair distribution function data confirm large structural similarity over long-range and at the atomic scale for these materials. However, they show distinct electrochemical properties and kinetic behaviour arising from the different anion environments and the consequent difference in cationic electrostatic repulsion. In comparison with Li2VO3 with an active V4+/5+ redox reaction, the material Li2VO2F with oxofluoro anions and the partial activity of V3+/5+ redox reaction favor higher theoretical capacity (460 mA h g-1vs. 230 mA h g-1), higher voltage (2.5 V vs. 2.2 V), lower polarization (0.1 V vs. 0.3 V) and faster Li+ chemical diffusion (~10-9 cm2 s-1vs. ~10-11 cm2 s-1). This work not only provides insights into the understanding of anion chemistry, but also suggests the rational design of new mixed-anion battery materials

Combining local preferences with multi-criteria decision analysis and linear optimisation to develop feasible energy concepts in small communities

In Germany over 700 energy cooperatives were established since 2006 and about 46% of installed renewable energy can be referred to as community energy. Decentralised community energy resources are often abundant in smaller, more rural communities. But these often lack the resources to develop extensive energy concepts and thus exploit these resources in a consistent way. Energy system analysis (ESA) offers useful insights in this context, but many energy system models focus on techno-economic aspects, without considering social aspects such as individual preferences. Much research in previous years has attempted to link social aspects and ESAs, often by employing a combination of ESA and multi-criteria decisions analysis (MCDA) tools. This paper presents an integrated participatory approach to developing feasible energy scenarios for small communities, with a focus on the transferability of the method and the consideration of uncertainties. For one exemplary municipality in south west Germany, stakeholder workshops are combined with ESA and MCDA. A total of eight alternatives for the 2030 energy system are elaborated, which vary in terms of the optimization objective between total costs, CO2 emissions and net energy imports. The three alternatives optimized with respect to just one criteria can be rejected. Instead the community should focus on the remaining intermediate scenarios, which achieve the highest overall performance scores and are stable to variations in the criteria weights. Similarities between these five alternatives mean that concrete recommendations about building-level measures can be derived, supported by simply tools that are made available to the community

High‐Entropy Sulfides as Highly Effective Catalysts for the Oxygen Evolution Reaction

With respect to efficient use of diminishing or harder to reach energy resources, the catalysis of processes that will otherwise require high overpotentials is a very important application in today\u27s world. As a newly developed class of materials, high-entropy sulfides (HESs) are promising electrocatalysts for a variety of different reactions. In this report, HESs containing five or six transition metals are synthesized in a one-step mechanochemical process. Seven HESs of Pnma (M:S≈1:1) and three Pa-3 (M:S = 1:2) structures are investigated as electrocatalysts for the oxygen evolution reaction (OER). The performances and properties of the HESs with different compositions and structures are compared with each other and with commercial IrO2 as reference material, in terms of OER overpotential, Tafel slope, electrochemically active surface area, ionic conductivity, and durability. The structural and chemical properties of these HESs are determined by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy. Most of the HESs show excellent and promising performance as OER electrocatalysts under alkaline conditions, and outperform the reference OER catalyst IrO2

Human Female Genital Tract Infection by the Obligate Intracellular Bacterium Chlamydia trachomatis Elicits Robust Type 2 Immunity

While Chlamydia trachomatis infections are frequently asymptomatic, mechanisms that regulate host response to this intracellular Gram-negative bacterium remain undefined. This investigation thus used peripheral blood mononuclear cells and endometrial tissue from women with or without Chlamydia genital tract infection to better define this response. Initial genome-wide microarray analysis revealed highly elevated expression of matrix metalloproteinase 10 and other molecules characteristic of Type 2 immunity (e.g., fibrosis and wound repair) in Chlamydia-infected tissue. This result was corroborated in flow cytometry and immunohistochemistry studies that showed extant upper genital tract Chlamydia infection was associated with increased co-expression of CD200 receptor and CD206 (markers of alternative macrophage activation) by endometrial macrophages as well as increased expression of GATA-3 (the transcription factor regulating TH2 differentiation) by endometrial CD4+ T cells. Also among women with genital tract Chlamydia infection, peripheral CD3+ CD4+ and CD3+ CD4- cells that proliferated in response to ex vivo stimulation with inactivated chlamydial antigen secreted significantly more interleukin (IL)-4 than tumor necrosis factor, interferon-γ, or IL-17; findings that repeated in T cells isolated from these same women 1 and 4 months after infection had been eradicated. Our results thus newly reveal that genital infection by an obligate intracellular bacterium induces polarization towards Type 2 immunity, including Chlamydia-specific TH2 development. Based on these findings, we now speculate that Type 2 immunity was selected by evolution as the host response to C. trachomatis in the human female genital tract to control infection and minimize immunopathological damage to vital reproductive structures. © 2013 Vicetti Miguel et al