Influence of structural disorder and large-scale geometric fluctuations on the Coherent Transport of Metallic Junctions and Molecular Wires

Structural disorder is present in almost all experimental measurements of electronic transport through single molecules or molecular wires. To assess its influence on the conductance is computationally demanding, because a large number of conformations must be considered. Here we analyze an approximate recursive layer Green function approach for the ballistic transport through quasi one-dimensional nano-junctions. We find a rapid convergence of the method with its control parameter, the layer thickness, and good agreement with existing experimental and theoretical data. Because the computational effort rises only linearly with system size, this method permits treatment of very large systems. We investigate the conductance of gold- and silver wires of different sizes and conformations. For weak electrode disorder and imperfect coupling between electrode and wire we find conductance variations of approximately 20%. Overall we find the conductance of silver junctions well described by the immediate vicinity of narrowest point in the junction, a result that may explain the observation of well-conserved conductance plateaus in recent experiments on silver junctions. In an application to flexible oligophene wires, we find that strongly distorted conformations that are sterically forbidden at zero temperature, contribute significantly to the observed average zero-bias conductance of the molecular wire

A method to account for variation of average compressor inlet pressure during instantaneous distortion analyses

A method is presented to calculate the available surge margin as a function of time and incorporate it into an instantaneous distortion analysis. Results show that inlet pressure variations which cause only a small change at the compressor exit can cause a significant variation in the available surge margin

Merkel, B. & Bergner, G.: Gewerbeflächenausweisung und Flächenverbrauch : Beitrag zur naturverträglichen Siedlungsentwicklung

Wenn in Deutschland im Jahre 2003 die Siedlungs- und Verkehrsfläche täglich um 93 Hektar zunahm, sind die Auswirkungen dieser fortschreitenden Flächeninanspruchnahme gewaltig. Eine Schlüsselrolle beim Flächenverbrauch kommt den Gewerbegebieten zu. Der erste Teil der Studie analysiert die Ausweisung von insgesamt 51 Gewerbegebieten in Bayern, Baden-Württemberg und Thüringen. Nach definierten Auswahlkriterien werden die Gebiete in „positive“ und „negative“ Fallbeispiele gegliedert. In übersichtlicher Weise sind die wichtigsten Aspekte und Kriterien der verschiedenen Fallbeispiele nachvollziehbar aufgelistet und zusammengefasst. Im zweiten Teil der Studie werden mit Hilfe von Fotos, Luftbildern und Karten die flächenhaften Auswirkungen der Gewerbegebiete anschaulich dargestellt

Isabelle/PIDE as Platform for Educational Tools

The Isabelle/PIDE platform addresses the question whether proof assistants of the LCF family are suitable as technological basis for educational tools. The traditionally strong logical foundations of systems like HOL, Coq, or Isabelle have so far been counter-balanced by somewhat inaccessible interaction via the TTY (or minor variations like the well-known Proof General / Emacs interface). Thus the fundamental question of math education tools with fully-formal background theories has often been answered negatively due to accidental weaknesses of existing proof engines. The idea of "PIDE" (which means "Prover IDE") is to integrate existing provers like Isabelle into a larger environment, that facilitates access by end-users and other tools. We use Scala to expose the proof engine in ML to the JVM world, where many user-interfaces, editor frameworks, and educational tools already exist. This shall ultimately lead to combined mathematical assistants, where the logical engine is in the background, without obstructing the view on applications of formal methods, formalized mathematics, and math education in particular.Comment: In Proceedings THedu'11, arXiv:1202.453

THE EFFECTS OF THE MICRO-MARKET STRUCTURE ON ILLINOIS ELEVATOR SPATIAL CORN PRICE DIFFERENTIALS

Corn price differentials among Illinois elevators can often exceed transportation costs. Using primary data, we examine the effects of micro-market structure variables on the differentials in bids prices offered by Illinois elevators. Our findings suggest the existence of a highly developed, responsive market of competing firms, operating in an industry that can be characterized by monopsonistic competition, and to some extent by seasonally induced market power. Local supply conditions, firm productive efficiency, and their operating practices influence price differentials. Further, firm type, final market destination of the grain, and period of the marketing year affect price differentials.Market structure, Corn price differentials, Marketing,

'Transport to Where?': Reflections on the problem of value and time à propos an awkward practice in medical research.

Based upon Kenyan ethnography, this article examines the gap between the bioethics aversion to value transfers in clinical trials, and research participants' and researchers' expectations of these. This article focuses upon so-called 'transport reimbursement' (TR): monetary payments to participants that are framed as mere refund of transport expenses, but which are of considerable value to recipients. The interest in this case lies not so much in the unsurprising gap between regulatory norms and poor study subjects' lives, but in the way in which this discrepancy between bioethical discourse and materialities of survival is silenced. In spite of the general awareness that TR indeed is about the material value of research, about value calculation, and expectations of return, it is not publicly discussed as such - unless ironically, in jest, or in private. This double-blindness around 'reimbursement' has provoked discussions among ethicists and anthropologists, some of which propose that the work that generates scientific value should be recognised as labour and participants, accordingly, paid. Here, this paper argues that such a re-vision of trial participation as work rather than as a gift for the public good, risks abrogating the possibility of 'the public' that is not only a precondition of public medical science, but also its potential product. The supposedly radical solution of tearing away the veils of misrecognition that 'free' gifting ideology lays upon the realities of free labour, though analytically plausible, fails to recognise the utopian openings within clinical trial transactions that point beyond the present - towards larger forms of social association, and towards future alignments of scientific possibilities and human lives

Sipping Fuel and Saving Lives: Increasing Fuel Economy without Sacrificing Safety

Demonstrates how new fuel-efficiency technologies make it possible, and advisable, to significantly increase the fuel economy of motor vehicles without compromising their safety

Monte Carlo simulations of the directional-ordering transition in the two-dimensional classical and quantum compass model

A comprehensive study of the two-dimensional (2D) compass model on the square lattice is performed for classical and quantum spin degrees of freedom using Monte Carlo and quantum Monte Carlo methods. We employ state-of-the-art implementations using Metropolis, stochastic series expansion and parallel tempering techniques to obtain the critical ordering temperatures and critical exponents. In a pre-investigation we reconsider the classical compass model where we study and contrast the finite-size scaling behavior of ordinary periodic boundary conditions against annealed boundary conditions. It is shown that periodic boundary conditions suffer from extreme finite-size effects which might be caused by closed loop excitations on the torus. These excitations also appear to have severe effects on the Binder parameter. On this footing we report on a systematic Monte Carlo study of the quantum compass model. Our numerical results are at odds with recent literature on the subject which we trace back to neglecting the strong finite-size effects on periodic lattices. The critical temperatures are obtained as $T_\mathrm{c}=0.1464(2)J$ and $T_\mathrm{c}=0.055(1)J$ for the classical and quantum version, respectively, and our data support a transition in the 2D Ising universality class for both cases.Comment: 8 pages, 7 figures, differs slightly from published versio

Sparse Probit Linear Mixed Model

Linear Mixed Models (LMMs) are important tools in statistical genetics. When used for feature selection, they allow to find a sparse set of genetic traits that best predict a continuous phenotype of interest, while simultaneously correcting for various confounding factors such as age, ethnicity and population structure. Formulated as models for linear regression, LMMs have been restricted to continuous phenotypes. We introduce the Sparse Probit Linear Mixed Model (Probit-LMM), where we generalize the LMM modeling paradigm to binary phenotypes. As a technical challenge, the model no longer possesses a closed-form likelihood function. In this paper, we present a scalable approximate inference algorithm that lets us fit the model to high-dimensional data sets. We show on three real-world examples from different domains that in the setup of binary labels, our algorithm leads to better prediction accuracies and also selects features which show less correlation with the confounding factors.Comment: Published version, 21 pages, 6 figure