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.

Mineral Trioxide Aggregate Material Use in Endodontic Treatment: A Review of the Literature

Objective The purpose of this paper was to review the composition, properties, biocompatibility, and the clinical results involving the use of mineral trioxide aggregate (MTA) materials in endodontic treatment. Methods Electronic search of scientific papers from January 1990 to August 2006 was accomplished using PubMed and Scopus search engines (search terms: MTA, GMTA, WMTA, mineral AND trioxide AND aggregate). Results Selected exclusion criteria resulted in 156 citations from the scientific, peer-reviewed dental literature. MTA materials are derived from a Portland cement parent compound and have been demonstrated to be biocompatible endodontic repair materials, with its biocompatible nature strongly suggested by its ability to form hydroxyappatite when exposed to physiologic solutions. With some exceptions, MTA materials provide better microleakage protection than traditional endodontic repair materials using dye, fluid filtration, and bacterial penetration leakage models. In both animal and human studies, MTA materials have been shown to have excellent potential as pulp-capping and pulpotomy medicaments but studies with long-term follow-up are limited. Preliminary studies suggested a favorable MTA material use as apical and furcation restorative materials as well as medicaments for apexogenesis and apexification treatments; however, long-term clinical studies are needed in these areas. Conclusion MTA materials have been shown to have a biocompatible nature and have excellent potential in endodontic use. MTA materials are a refined Portland cement material and the substitution of Portland cement for MTA products is presently discouraged. Existing human studies involving MTA materials are very promising, however, insufficient randomized, double-blind clinical studies of sufficient duration exist involving MTA for all of its clinical indications. Further clinical studies are needed in these areas

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.

Instrumented Lumbar Corpectomy and Spinal Reconstruction Comparing rhBMP-2/Compression-Resistant Matrix, rhBMP-2/Absorbable Collagen Sponge/Ceramic Granules Mixture, and Autograft in Two Different Devices: A Study in Sheep

Study Design. Fusion success with rhBMP-2 and autograft in titanium or PEEK corpectomy devices was evaluated in a sheep lumbar corpectomy model. The 6 treatment groups included titanium mesh or PEEK corpectomy devices filled with rhBMP-2 on a compression-resistant matrix (CRM) carrier; rhBMP-2 in a morselized absorbable collagen sponge (ACS) carrier combined with resorbable ceramic granules; and autograft. Objective. The aim of this study was to determine fusion rates associated with 2 different preparations of rhBMP-2 as well as autograft in an instrumented ovine lumbar corpectomy model 6 months postoperatively. Summary of Background Data. Vertebral reconstruction with corpectomy devices requires bone graft. Bone graft substitutes have the potential to avoid a second operation, donor site pain, and attendant morbidity associated with autograft. Methods. Twenty-four sheep in 6 treatment groups underwent lumbar corpectomy via a retroperitoneal trans-psoas approach. Spines were reconstructed with autograft, rhBMP-2 on a CRM, or rhBMP-2 on an ACS mixed with ceramic granules. Grafting materials were placed in either a titanium mesh or PEEK conduit in spines with internal fixation. Computed tomographic (CT) scans were evaluated for fusion. Undecalcified histology was used to evaluate for fusion as well as the amount and extent of graft incorporation and graft resorption. Results. Regardless of corpectomy device used, rhBMP-2/CRM or rhBMP-2/ACS with MASTERGRAFT resulted in a 100% fusion rate. The autograft group had a lower (75%) radiographic fusion rate. Using either preparation of rhBMP-2 resulted in the length of the defect filling with solid bone. Autograft fragments and ceramic granules were incorporated into the fusion masses with much of the ceramic granules being resorbed by 6 months. Conclusion. Both of the rhBMP-2 formulations have the potential to effect bony fusion and vertebral reconstruction within the corpectomy devices

Economics of Pollution Trading for SO2 and NOx

For years economists have urged policymakers to use market-based approaches such as cap-and-trade programs or emission taxes to control pollution. The SO2 allowance market created by Title IV of the 1990 U.S. Clean Air Act Amendments represents the first real test of the wisdom of economists’ advice. Subsequent urban and regional applications of NOx emission allowance trading took shape in the 1990s in the United States, culminating in a second large experiment in emission trading in the eastern United States that began in 2003. This paper provides an overview of the economic rationale for emission trading and a description of the major U.S. programs for sulfur dioxide (SO2) and nitrogen oxides (NOx). We evaluate these programs along measures of performance including cost savings, environmental integrity, and incentives for technological innovation. We offer lessons for the design of future programs including, most importantly, those reducing carbon dioxide.sulfur dioxide, nitrogen oxides, emission trading, power plants, air pollution