Slater screening constants in atomic and molecular orbitals

Slater screening constants in atomic and molecular orbital

Current-driven magnetization decrease in single crystalline ferromagnetic manganese oxide

The electrical and magnetic response to a bias current has been investigated in a singlecrystalline ferromagnetic manganese oxide $\Pr_{0.8}$Ca$_{0.2}$MnO$_3$ . A significant decrease of the magnetization is observed at the same threshold current where a non-linearity of V-I characteristics appears. Such a behavior cannot be understood in the framework of the filamentary picture usually invoked for the non linearity of the other manganese oxides. Instead, an analogy with spintronic features might be useful and experimental signatures seem to be in agreement with excitations of spin waves by an electric current. This provides an example of a bulk system in which the spin polarized current induces a macroscopic change in the magnetization.Comment: 3 pages, 4 figure

Effects of temporal variability of disturbance on the succession in marine fouling communities in northern-central Chile

We investigated the effects of temporal variability in a disturbance regime on fouling communities at two study sites in a northern-central Chilean bay. Fouling assemblages grown on artificial settlement substrata were disturbed by mechanical removal of biomass at different time intervals. Using one single disturbance frequency (10 disturbance events over 5 months) we applied 7 different temporal disturbance treatments: a constant disturbance regime (identical intervals between disturbance events), and 6 variable treatments where both variableness and sequences of intervals between disturbance events were manipulated. Two levels of temporal variableness (low and high, i.e. disturbance events were either dispersed or highly clumped in time) in the disturbance regime were applied by modifying the time intervals between subsequent disturbance events. To investigate the temporal coupling between disturbance events and other ecological processes (e.g. larval supply and recruitment intensity), three different sequences of disturbance intervals were nested in each of the two levels of temporal variableness. Species richness, evenness, total abundance, and structure of communities that experienced the various disturbance regimes were compared at the end of the experiment (15 days after the last disturbance event). Disturbance strongly influenced the community structure and led to a decrease in evenness and total abundance but not species richness. In undisturbed reference communities, the dominant competitor Pyura chilensis (Tunicata) occupied most available space while this species was suppressed in all disturbed treatments. Surprisingly, neither temporal variableness in the disturbance regime nor the sequence of intervals between disturbance events had an effect on community structure. Temporal variability in high disturbance regimes may be of minor importance for fouling communities, because they are dominated by opportunistic species that are adapted to rapidly exploit available space

Bayesian Analysis of a Japanese Meat Demand System: A Robust Likelihood Approach

This paper presents an application of Bayesian analysis to an AIDS model of Japanese meat demand extending previous approaches in three ways: (1) The methodology employed is robust with respect to the likelihood function but retains the generic, easily programmable character of algorithms offered by Monte Carlo Integration approaches based on the normal likelihood function. (2) In addition to inequality constraints, linear exact restrictions and stochastic prior information are subjected to a Bayesian posterior analysis of validity and incorporated into Bayesian point estimates of model parameters and elasticities. (3) In order to assess the influence of the prior density on posterior distributions of model parameters relative to the likelihood, a measure quantifying the "degree of prior influence" on the posterior is defined. Das Diskussionspapier stellt eine Bayes'sche Analyse eines AIDS Modells Japanischer Fleischnachfrage vor, die eine Erweiterung fruherer Ansatze in den folgenden drei Punkten darstellt:(1) Die verwendete Methode ist robust bezuglich der Likelihood Funktion, erhalt dabei aber die Flexibilitat und einfache Umsetzung von Algorithmen basierend auf Monte Carlo Integration und der Annahme der Normalverteilung. (2) Zusatzlich zu Ungleichheitsbedingungen werden exakte Restriktionen und stochastische a-priori Information einer Bayes'schen a-posteriori Analyse unterzogen und in die Bayes'sche Punktschatzung von Parametern und Elastizitaten einbezogen. (3) Ein Index zur Messung des Einflusses der a-priori Information auf die a-posteriori Verteilung der Modellparameter wird vorgestellt.Demand and Price Analysis,

Electronic Hong-Ou-Mandel interferometry in two-dimensional topological insulators

The edge states of a two-dimensional topological insulator are characterized by their helicity, a very remarkable property which is related to the time-reversal symmetry and the topology of the underlying system. We theoretically investigate a Hong-Ou-Mandel like setup as a tool to probe it. Collisions of two electrons with the same spin show a Pauli dip, analogous to the one obtained in the integer quantum Hall case. Moreover, the collisions between electrons of opposite spin also lead to a dip, known as $\mathbb{Z}_{2}$ dip, which is a direct consequence of the constraints imposed by time-reversal symmetry. In contrast to the integer quantum Hall case, the visibility of these dips is reduced by the presence of the additional edge channels, and crucially depends on the properties of the quantum point contact. As a unique feature of this system, we show the possibility of three-electron interference, which leads to a total suppression of the noise independently of the point contact configuration. This is assured by the peculiar interplay between Fermi statistics and topology. This work intends to extend the domain of applicability of electron quantum optics.Comment: 12 pages, 7 figure

RURAL HOUSEHOLD FRUIT AND VEGETABLE CONSUMPTION IN CHINA

A two-stage budgeting model using Chinese rural survey data is used to assess rural Chinese household food demand. The second-step includes 11 categories including 4 vegetable groups and 3 fruit groups. The results indicate that grains are still important staple foods and that vegetables are important non-staple foods relative to fruits.Consumer/Household Economics,

AGGREGATE FOOD DEMAND ANALYSIS FOR A TRANSITIONAL ECONOMY: AN APPLICATION TO CHINESE HOUSEHOLD EXPENDITURE DATA

An analytical framework to assess the effects of changing income and socio-demographic distributions on aggregate food demand functions in transitional economies is presented. Ignoring such distributional effects can lead to biased estimates of aggregate demand elasticities. The proposed method is applied to Chinese urban household expenditure survey data. The results indicate that the drastic distributional changes that have occurred in China have had notable effects on estimated demand elasticities for both food and non-food commodity groups.Consumer/Household Economics, Demand and Price Analysis,

ASSESSING THE EFFECTIVENESS OF MPP AND TEA ADVERTISING AND PROMOTION EFFORTS IN THE JAPANESE MARKET FOR MEATS

An Inverse Almost Ideal Demand System is utilized to determine the effectiveness of Market Promotion Program (MPP) and Target Export Assistance (TEA) advertising and promotion expenditures in the Japanese market for meat. Using annual data, it is found that beef advertising and promotion has had a positive and significant effect on the demand for beef. There is insufficient evidence to conclude that pork and poultry advertising and promotion increased the demand for either commodity.Marketing,

ACCOUNTING FOR AGGREGATION BIAS IN ALMOST IDEAL DEMAND SYSTEMS

This study revisits the consistent aggregation (over households) property of almost ideal demand system (AIDS) models and presents a method to explicitly account for expenditure aggregation bias when estimating the aggregate AIDS model with time-series data. Ignoring aggregation bias can lead to biased and inconsistent parameter estimates and can cause aggregate demand functions to be inconsistent with the demand functions at the individual household level. Recognizing the general limited information contained in aggregate time-series data for explicitly modeling aggregation bias, we present a new method of constructing an aggregation bias term that is derived from the proportions of household in different income groups. This information is generally available in developed economies. We use this framework to estimate aggregate meat demand within a complete demand system based on U.S. annual expenditure data.Demand and Price Analysis,