On the zero mass limit of tagged particle diffusion in the 1-d Rayleigh-gas

We consider the M -> 0 limit for tagged particle diffusion in a 1-dimensional Rayleigh-gas, studied originaly by Sinai and Soloveichik (1986), respectively by Szasz and Toth (1986). In this limit we derive a new type of model for tagged paricle diffusion, with Calogero-Moser-Sutherland (i.e. inverse quadratic) interaction potential between the two central particles. Computer simulations on this new model reproduce exactly the numerical value of the limiting variance obtained by Boldrighini, Frigio and Tognetti (2002).Comment: Dedicated to Domokos Szasz on his 65th birthda

Effects of Price Shocks to Consumer Demand. Estimating the QUAIDS Demand System on Czech Household Budget Survey Data

The purpose of his paper is to describe consumer behavior in the Czech Republic by estimating a demand system in which demand depends on income and prices, but also on other factors such as age, size of the household, and position on the labor market. We combine Household Budget Survey data with information on prices from alternative sources between 2000 and 2008. The main focus of our analysis is to provide estimates of both own-and cross-price and income elasticities, which can be used among other things when analyzing the impact of exogenous price changes on consumer demand. Based on our estimates, the commodity bundles of food, energy, and health and bodycare are necessary goods, as their budget elasticity is positive and below one at the same time. Clothing and shoes, transportation and communication, and education and leisure are luxury goods, with income elasticity above one. The own-price elasticities are negative for all commodity groups, as expected. The cross elasticities seem to be smaller than the own elasticities.We found expenditure on energy and transportation and communication to be the most affected by changes in their own prices. We use our estimates to analyze the impact of regulated price changes on consumer demand and discuss the further potential use of our results.Consumer behavior, demand systems, price and income elasticities, regulated prices.

Ezetimibe therapy: mechanism of action and clinical update.

The lowering of low-density lipoprotein cholesterol (LDL-C) is the primary target of therapy in the primary and secondary prevention of cardiovascular events. Although statin therapy is the mainstay for LDL-C lowering, a significant percentage of patients prescribed these agents either do not achieve targets with statin therapy alone or have partial or complete intolerance to them. For such patients, the use of adjuvant therapy capable of providing incremental LDL-C reduction is advised. One such agent is ezetimibe, a cholesterol absorption inhibitor that targets uptake at the jejunal enterocyte brush border. Its primary target of action is the cholesterol transport protein Nieman Pick C1 like 1 protein. Ezetimibe is an effective LDL-C lowering agent and is safe and well tolerated. In response to significant controversy surrounding the use and therapeutic effectiveness of this drug, we provide an update on the biochemical mechanism of action for ezetimibe, its safety and efficacy, as well as the results of recent randomized studies that support its use in a variety of clinical scenarios

Short-Term Forecasting of Czech Quarterly GDP Using Monthly Indicators

We evaluate the out-of-sample forecasting performance of six competing models at horizons of up to three quarters ahead in a pseudo-real time setup. All the models use information in monthly indicators released ahead of quarterly GDP. We estimate two models – averaged vector autoregressions and bridge equations – relying on just a few monthly indicators. The remaining four models condition the forecast on a large set of monthly series. These models comprise two standard principal components models, a dynamic factor model based on the Kalman smoother and a generalized dynamic factor model. We benchmark our results to the performance of a naïve model and the historical near-term forecasts of the Czech National Bank’s staff. The findings are also compared with a related study conducted by ECB staff (Barhoumi et al., 2008). In the Czech case, standard principal components is the most precise model overall up to three quarters ahead. However, the CNB staff’s historical forecasts were the most accurate one quarter ahead.Bridge models, dynamic factor models, GDP forecasting, principal components, real-time evaluation.