2,380 research outputs found

    Firm growth, European industry dynamics and domestic business cycles

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    Based on the empirical firm growth literature and on heterogeneous (microeconomic) adjustment models, this paper empirically investigates the impact of European industry fluctuations and domestic business cycles on the growth performance of European firms. Since the implementation of the Single market program (SMP) the EU 27 member states share a common market. Accordingly, the European industry business cycle is expected to become a more influential predictor of European firms' behavior at the expense of domestic fluctuations. Empirically, the results of a two-part model for a sample of European manufacturing firms reject this hypothesis. Additionally, subsidiaries of Multinational Enterprises (MNEs) constitute the most stable firm cohort throughout the observed business cycle.Firm growth, industry dynamics, domestic business cycle, European integration, multinational enterprises, two-part model

    First-principles thermodynamic screening approach to photo-catalytic water splitting with co-catalysts

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    We adapt the computational hydrogen electrode approach to explicitly account for photo-generated charges and use it to computationally screen for viable catalyst/co-catalyst combinations for photo-catalytic water splitting. The hole energy necessary to thermodynamically drive the reaction is employed as descriptor for the screening process. Using this protocol and hybrid-level density-functional theory we show that water oxidation on bare TiO2 surfaces is thermodynamically more complex than previously thought. This motivates a screening for suitable co-catalysts for this half-reaction, which we carry out for Au particles down to the non-scalable size regime. We find that almost all small Au clusters studied are better suited for water photo-oxidation than an extended Au(111) surface or bare TiO2 facets.Comment: 5 pages, 3 figure

    Fully restricted linear regression: A pedagogical note

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    This paper presents a comprehensive approach to estimation and hypothesis testing under a set of full restrictions, some of these arising from adding-up conditions on the endogenous variable. In contrast to the existing statistical literature, this paper uses an argumentation style familiar from classical econometric textbooks, to provide an insightful, straightforward, and nevertheless rigorous exposition of this topic.Restricted least squares Adding-up Singularity Wald-Test SUR.

    On autoregressive errors in singular systems of equations

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    Dhrymes (1994, Econometric Theory, 10, 254-285) demonstrates the arising identification and estimation problems in singular equation systems when the error vector obeys an autoregressive scheme, as an extension of restricted least squares. Unfortunately, his main theorem concerning the identification of such systems, does not hold in general, though.identification

    Modelling Fertility: A Semi-Parametric Approach

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    This article presents a categorical model of fertility based on the statistical theory of the Generalised Linear Model (GLM). Focussing on the individual probability of giving birth to a child, we derive distributions which can be embedded in a GLM framework. A major advance of that methodology is the knowledge of the distribution of the random variable, which leads to a Maximum Likelihood estimation procedure. The approach takes into account the smooth shapes of parameter development over the age of the mother as well as over time. The estimation of this semi-parametric approach is done using the Local-Likelihood-method. The presented method provides stable results of the fertility, especially for smaller populations. This is illustrated by using a data set which consists of less than 100,000 inhabitants. Dieser Aufsatz stellt ein kategorielles Modell der Geburtenhäufigkeit auf Basis der statistischen Theorie des Verallgemeinerten Linearen Modells (VLM) vor. Ausgehend von individuellen Gebär-Wahrscheinlichkeiten leiten wir Verteilungen ab, welche in einen VLM-Rahmen eingebettet werden können. Ein besonderer Vorteil dieser Methode ist das Wissen um die Verteilung der Zufallsvariablen, welches ein Maximum-Likelihood Schätzverfahren ermöglicht. Der Ansatz berücksichtigt den gleichmäßigen Verlauf der Parameter-Entwicklung über das Alter der Mutter und über die Zeit. Die Schätzung dieses semi-parametrischen Ansatzes erfolgt mit Hilfe der Local-Likelihood-Methode. Die vorgestellte Methode liefert solide Ergebnisse zur Geburtenhäufigkeit, insbesondere bei kleineren Bevölkerungszahlen. Dies wird anhand eines Datensatzes mit weniger als 100.000 Einwohnern gezeigt.Geburtenentwicklung ; Semiparametrische Schätzung ; Verallgemeinertes lineares Modell; ;

    Charge constrained density functional molecular dynamics for simulation of condensed phase electron transfer reactions

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    We present a plane-wave basis set implementation of charge constrained density functional molecular dynamics (CDFT-MD) for simulation of electron transfer reactions in condensed phase systems. Following earlier work of Wu et al. Phys. Rev. A 72, 024502 (2005), the density functional is minimized under the constraint that the charge difference between donor and acceptor is equal to a given value. The classical ion dynamics is propagated on the Born-Oppenheimer surface of the charge constrained state. We investigate the dependence of the constrained energy and of the energy gap on the definition of the charge, and present expressions for the constraint forces. The method is applied to the Ru2+-Ru3+ electron self-exchange reaction in aqueous solution. Sampling the vertical energy gap along CDFT-MD trajectories, and correcting for finite size effects, a reorganization free energy of 1.6 eV is obtained. This is 0.1-0.2 eV lower than a previous estimate based on a continuum model for solvation. smaller value for reorganization free energy can be explained by fact that the Ru-O distances of the divalent and trivalent Ru-hexahydrates are predicted to be more similar in the electron transfer complex than for the separated aqua-ions.Comment: 12 pages, 7 figure

    Distance Matters - Evidence from Professional Team Sports

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    This paper assesses the role of distance in professional team sports, taking the example of football (soccer). We argue that a team’s performance in terms of scored and conceded goals decreases with the distance to the foreign playing venue. To test this hypothesis empirically, we investigate 6,389 away games from the German Football Premier League (’Erste Deutsche Bundesliga’) between the playing seasons 1986-87 and 2006-07. We find that distance contributes significantly in explaining a guest team’s propensity to concede goals, but not so for scoring goals. Focusing on the difference between scored and conceded goals (‘goal difference’) as a measure of the overall success of a football team, we observe a significant and non-monotonic impact of distance on team performance.Professional team performance, distance, event count data, poisson regression model

    Optimum bias for fast-switching free energy calculations

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    We derive the bias function that minimizes the statistical error of free energy differences calculated in work-biased fast-switching simulations. The optimum bias function is compared to other bias functions using a particle pulled through a viscous fluid as an illustrative example. Our analysis indicates that the uncertainty in the free energy is smallest if both dominant and typical work values are sampled with high frequency.Comment: 6 pages, 4 figure

    Single molecule pulling with large time steps

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    Recently, we presented a generalisation of the Jarzynski non-equilibrium work theorem for phase space mappings. The formalism shows that one can determine free energy differences from approximate trajectories obtained from molecular dynamics simulations in which very large timesteps are used. In this work we test the method by simulating the force induced unfolding of a deca-alanine helix in vacuum. The excellent agreement between results obtained with a small, conservative time step of 0.5 fs and results obtained with a time step of 3.2 fs (i.e., close to the stability limit) indicates that the large time step approach is practical for such complex biomolecules. We further adapt the method of Hummer and Szabo for the simulation of single-molecule force spectroscopy experiments to the large time step method. While trajectories generated with large steps are approximate and may be unphysical - in the simulations presented here we observe a violation of the equipartition theorem - the computed free energies are exact in principle. In terms of efficiency, the optimum time step for the unfolding simulations lies in the range 1-3 fs.Comment: 8 pages, 8 figure
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