Physics Opportunities with Polarized e- and e+ Beams at TESLA

Beam polarization at e+ e- linear colliders will be a powerful tool for high precision analyses. Often it is assumed that the full information from polarization effects is provided by polarization of the electron beam and no further information can be obtained by the simultaneous polarization of the positrons. In this paper we point out the advantages of polarizing both beams, and summarize the polarization-related results of the Higgs, Electroweak, QCD, SUSY and Alternative Theories working groups of the ECFA/DESY workshop for a planned linear collider operating in the energy range sqrt{s}= 500-800 GeV.Comment: 36 pages, 21 postscript figures, latex using epsfi

Forecasting Random Walks Under Drift Instability

This paper considers forecast averaging when the same model is used but estimation is carried out over different estimation windows. It develops theoretical results for random walks when their drift and/or volatility are subject to one or more structural breaks. It is shown that compared to using forecasts based on a single estimation window, averaging over estimation windows leads to a lower bias and to a lower root mean square forecast error for all but the smallest of breaks. Similar results are also obtained when observations are exponentially down-weighted, although in this case the performance of forecasts based on exponential down-weighting critically depends on the choice of the weighting coefficient. The forecasting techniques are applied to monthly inflation series of 21 OECD countries and it is found that average forecasting methods in general perform better than using forecasts based on a single estimation window.forecast combinations, averaging over estimation windows, exponentially down-weighting observations, structural breaks

Light-Scattering by Longitudinal phonons in Supercooled Molecular Liquids II: Microscopic Derivation of the Phenomenological Equations

The constitutive equations for the orientational dynamics of a liquid formed of linear molecules are derived microscopically. The resulting generalised Langevin equations coincide with the phenomenological approach of Dreyfus et al. Formally exact expressions are given for the phenomenological coefficients and various constraints are shown to be consequences of this microscopic approach.Comment: 18 page

Labeling Policies in Food Markets: Private Incentives, Public Intervention, and Welfare Effects

This study considers the welfare impact of labeling policies of agricultural commodities with specific characteristics. Using a model of vertical differentiation, the effects on equilibrium and welfare levels are calculated. The introduction of the regulation and the emergence of two differentiated competitive markets leaves consumers and high-quality producers better off, while low-quality producers are worse off. With high costs and low quality differences, the total welfare impact of the regulation can be negative. Findings show that when high-quality producers can exercise market power, the regulation could be more easily accepted by producers, but it would have a negative effect on consumers.asymmetric information, food markets, labeling, market power, vertical differentiation, welfare effects, Agricultural and Food Policy,

Diagnostic Tests of Cross Section Independence for Nonlinear Panel Data Models

In this paper we discuss tests for residual cross section dependence in nonlinear panel data models. The tests are based on average pair-wise residual correlation coefficients. In nonlinear models, the definition of the residual is ambiguous and we consider two approaches: deviations of the observed dependent variable from its expected value and generalized residuals. We show the asymptotic consistency of the cross section dependence (CD) test of Pesaran (2004). In Monte Carlo experiments it emerges that the CD test has the correct size for any combination of N and T whereas the LM test relies on T large relative to N. We then analyze the roll-call votes of the 104th U.S. Congress and find considerable dependence between the votes of the members of Congress.cross-section dependence, nonlinear panel data model

A study of starting time in great hard X-ray flares

An analysis of the starting time in ten great hard X-ray bursts observed with the X-Ray Burst Spectrometer (HXRBS) is presented. It is shown that the impulsive phase of nine of them is composed of a preflash phase, during which the burst is observed up to an energy limit ranging from some tens of keV to 200 keV, followed ten to some tens of seconds afterwards by a flash phase, where the count rate rises simultaneously in all detector channels. For two events strong gamma-ray line emission is observed and is shown to start close to the onset of the flash phase

Variable Selection and Inference for Multi-period Forecasting Problems

This paper conducts a broad-based comparison of iterated and direct multi-step forecasting approaches applied to both univariate and multivariate models. Theoretical results and Monte Carlo simulations suggest that iterated forecasts dominate direct forecasts when estimation error is a first-order concern, i.e. in small samples and for long forecast horizons. Conversely, direct forecasts may dominate in the presence of dynamic model misspecification. Empirical analysis of the set of 170 variables studied by Marcellino, Stock and Watson (2006) shows that multivariate information, introduced through a parsimonious factor-augmented vector autoregression approach, improves forecasting performance for many variables, particularly at short horizons.