Study of stress corrosion in aluminum alloys

Mechanism of the stress corrosion cracking of high-strength aluminum alloys was investigated using electrochemical, mechanical, and electron microscopic techniques. The feasibility of detecting stress corrosion damage in fabricated aluminum alloy parts by nondestructive testing was investigated using ultrasonic surface waves and eddy currents

A Generative Model for Score Normalization in Speaker Recognition

We propose a theoretical framework for thinking about score normalization, which confirms that normalization is not needed under (admittedly fragile) ideal conditions. If, however, these conditions are not met, e.g. under data-set shift between training and runtime, our theory reveals dependencies between scores that could be exploited by strategies such as score normalization. Indeed, it has been demonstrated over and over experimentally, that various ad-hoc score normalization recipes do work. We present a first attempt at using probability theory to design a generative score-space normalization model which gives similar improvements to ZT-norm on the text-dependent RSR 2015 database

GUT-scale inflation with sizeable tensor modes

A sizeable tensor-to-scalar ratio, such as recently claimed by BICEP2, would imply a scale of inflation at the typical scale of supersymmetric grand unification. This could be an accident, or strong support for supersymmetric theories. Models of F-term hybrid inflation naturally connect the GUT scale with the inflationary scale, but they also predict the tensor-to-scalar ratio to be unmeasurably small. In this work we analyze a general UV embedding of F-term hybrid inflation into a supergravity theory with a general Kahler potential. The CMB observables are generated during the early phase of inflation, at large inflaton values, where the potential is dominated by Planck-suppressed operators. Tuning the leading higher-order terms can give an inflaton potential with sizeable tensor fluctuations and a field excursion which is still sub-Planckian but close to the Planck scale, as expected from the Lyth bound.Comment: 15 pages, 3 figures; v2: matches journal versio

Wheat / Flour Price Transmission and Agricultural Policies in Ukraine: A Markov-Switching Vector Error Correction Approach

The analysis of price transmission between raw and processed agricultural products in transition countries is complicated by the frequently changing conditions on their way from plan to market. We utilise a Markov-switching vector error correction model to allow for multiple regime shifts in the price relationship between wheat and wheat flour in Ukraine from June 2000 to November 2004. The analysis reveals four regimes. The observed temporal pattern of these regimes can be matched with certain political and economic events in Ukraine. In particular, we find a strong link between the 'high uncertainty' regime and discretionary policy interventions in 2003.Markov-switching vector error correction model, vertical price transmission, regime shifts, grain policies, Ukraine, Demand and Price Analysis, Industrial Organization, C22, Q11, Q18,

ESTIMATION ISSUES IN SINGLE COMMODITY GRAVITY TRADE MODELS

Recently gravity trade models are applied to disaggregated trade data. Here many zeros are characteristic. In the presence of excess zeros usual Poisson Pseudo Maximum Likelihood (PPML) is still consistent, the variance covariance matrix however is invalid. Correct economic interpretation however requires also the last. So alternative estimators are looked for. STAUB &WINKELMANN (2010) argue that zero-inflated count data models (i.e. zero-inflated Poisson / Negative Binomial Pseudo Maximum Likelihood (ZIPPML / ZINBPML)) are no alternative since under model misspecification these estimators are inconsistent. Yet zeroinflated Poisson Quasi-Likelihood (PQL) is a reliable alternative. It is consistent even under model misspecifications and beyond that robust against unobserved heterogeneity. Another alternative is a log-skew-normal Two-Part Model (G2PM) which generalises the standard lognormal Two-Part Model (2PM). It is insofar advantageous as it adjusts for (negative) skewness and regression coefficients retain usual interpretations as in log-normal models. PQL is useful for multiplicative gravity model estimation and G2PM for log-linear gravity model estimation. Exemplarily the estimators are applied to intra-European piglet trade to assess their empirical performance and applicability for single commodity trade flow analysis. The empirical part favours PQL but G2PM is a reliable alternative for other trade flow analyses. PQL and G2PM should become standard tools for single commodity trade flow analysis.Gravity Model, Excess Zeros, Poisson Quasi Likelihood, Generalised Two Part Model, Gravitationsmodell, Exzess an Nullen, Poisson Quasi Likelihood, Generalisiertes Zwei-Teile Modell, Agribusiness, Agricultural and Food Policy, Agricultural Finance, Demand and Price Analysis, Financial Economics,

Health benefits and health claims of probiotics: bridging science and marketing

Health claims for probiotics are evaluated by the Panel on Dietetic Products, Nutrition and Allergies of the European Food Safety Authority. Despite a substantial amount of basic and clinical research on the beneficial effects of probiotics, all of the evaluated claim applications thus far have received a negative opinion. With the restrictions on the use of clinical endpoints, validated biomarkers for gut health and immune health in relation to reduction in disease risk are needed. Clear-cut criteria for design as well as evaluation of future studies are needed. An open dialogue between basic and clinical scientists, regulatory authorities, food and nutrition industry, and consumers could bridge the gap between science and marketing of probiotic

Impacts of Export Controls On Wheat Markets During the Food Crisis 2007/2008 in Russia and Ukraine

This paper investigates the impacts of export controls in Russia and Ukraine on wheat world market price transmission during the 2007/2008 global food crisis. Russia and Ukraine aimed to reduce wheat exports induced by extraordinarily high world market prices to secure sufficient wheat supply on the domestic markets. Utilizing a Markov-Switching vector error correction model (MSVECM), we find that the temporary export restrictions induced negative effects on wheat markets in Russia and Ukraine. Although instability increased on the world markets itself, we have shown that the increase in the market instability was particularly pronounced in Russia and Ukraine. Also, the export restrictions dampened price transmission to the farmers’ prices, which pushed the growers’ prices below their long-run equilibrium level. Thus, investment incentives in wheat production which could result from high world market prices were foregone.International price transmission, wheat market, food crisis, Markov switching error correction model, Russia, Ukraine, Demand and Price Analysis, International Relations/Trade,