The neutron and its role in cosmology and particle physics

Experiments with cold and ultracold neutrons have reached a level of precision such that problems far beyond the scale of the present Standard Model of particle physics become accessible to experimental investigation. Due to the close links between particle physics and cosmology, these studies also permit a deep look into the very first instances of our universe. First addressed in this article, both in theory and experiment, is the problem of baryogenesis ... The question how baryogenesis could have happened is open to experimental tests, and it turns out that this problem can be curbed by the very stringent limits on an electric dipole moment of the neutron, a quantity that also has deep implications for particle physics. Then we discuss the recent spectacular observation of neutron quantization in the earth's gravitational field and of resonance transitions between such gravitational energy states. These measurements, together with new evaluations of neutron scattering data, set new constraints on deviations from Newton's gravitational law at the picometer scale. Such deviations are predicted in modern theories with extra-dimensions that propose unification of the Planck scale with the scale of the Standard Model ... Another main topic is the weak-interaction parameters in various fields of physics and astrophysics that must all be derived from measured neutron decay data. Up to now, about 10 different neutron decay observables have been measured, much more than needed in the electroweak Standard Model. This allows various precise tests for new physics beyond the Standard Model, competing with or surpassing similar tests at high-energy. The review ends with a discussion of neutron and nuclear data required in the synthesis of the elements during the "first three minutes" and later on in stellar nucleosynthesis.Comment: 91 pages, 30 figures, accepted by Reviews of Modern Physic

CATMoS: Collaborative Acute Toxicity Modeling Suite.

BACKGROUND: Humans are exposed to tens of thousands of chemical substances that need to be assessed for their potential toxicity. Acute systemic toxicity testing serves as the basis for regulatory hazard classification, labeling, and risk management. However, it is cost- and time-prohibitive to evaluate all new and existing chemicals using traditional rodent acute toxicity tests. In silico models built using existing data facilitate rapid acute toxicity predictions without using animals. OBJECTIVES: The U.S. Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) Acute Toxicity Workgroup organized an international collaboration to develop in silico models for predicting acute oral toxicity based on five different end points: Lethal Dose 50 (LD50 value, U.S. Environmental Protection Agency hazard (four) categories, Globally Harmonized System for Classification and Labeling hazard (five) categories, very toxic chemicals [LD50 (LD50≤50mg/kg)], and nontoxic chemicals (LD50>2,000mg/kg). METHODS: An acute oral toxicity data inventory for 11,992 chemicals was compiled, split into training and evaluation sets, and made available to 35 participating international research groups that submitted a total of 139 predictive models. Predictions that fell within the applicability domains of the submitted models were evaluated using external validation sets. These were then combined into consensus models to leverage strengths of individual approaches. RESULTS: The resulting consensus predictions, which leverage the collective strengths of each individual model, form the Collaborative Acute Toxicity Modeling Suite (CATMoS). CATMoS demonstrated high performance in terms of accuracy and robustness when compared with in vivo results. DISCUSSION: CATMoS is being evaluated by regulatory agencies for its utility and applicability as a potential replacement for in vivo rat acute oral toxicity studies. CATMoS predictions for more than 800,000 chemicals have been made available via the National Toxicology Program's Integrated Chemical Environment tools and data sets (ice.ntp.niehs.nih.gov). The models are also implemented in a free, standalone, open-source tool, OPERA, which allows predictions of new and untested chemicals to be made. https://doi.org/10.1289/EHP8495

Optimum design for correlated processes via eigenfunction expansions

In this paper we consider optimum design of experiments for correlated observations. We approximate the error component of the process by an eigenvector expansion of the corresponding covariance function. Furthermore we study the limit behavior of an additional white noise as a regularization tool. The approach is illustrated by some typical examples. (authors' abstract)Series: Research Report Series / Department of Statistics and Mathematic

Estimation and Experimental Design for Second Kind Regression Models

Estimation procedures and optimal designs for estimation of the individual parameters and of the global parameters are discussed under various conditions of prior knowledge. The extension to nonlinear parametrization of the response function ís based on the asymptotical validity of the results for the linear parametrization. For the case where the error variance and the dispersion matrix are unknown, an iterative estimation procedure is suggested. An example based on dental plaque pH profiles demonstrates the improvement that is achieved (a) through using the optimal design or a design that ís close to the optimal, and (b) through taking into account prior information. (author's abstract)Series: Forschungsberichte / Institut für Statisti

Moving Local Regression: The Weight Function

Moving local regression is a nonparametric technique for smoothing, interpolating and forecasting by means of locally fitted regression models. The paper explores the "optimal" structure of the weight function, taking into account the location of supporting points and the suspected behaviour of the remainder term, and surveys results on choice of weight functions in traditional moving local regression approaches. (author's abstract)Series: Forschungsberichte / Institut für Statisti

Optimal and Practicable Designs for Measuring Plaque pH-Profiles

In this paper we will show that the theory of optimal experimental design leads to quite different patterns of measurement. These patterns take into account (a) the structure of the ongoing process and (b) what parameters or characteristics are object of inference. We will demonstrate that the use of optimal designs or of designs that are close to optimal ones allows to reduce the sample size without decreasing the accuracy of the results. In Section 2 we present a model that is suitable to describe the pH-profile and we give some justification on an empirical basis. Section 3 discusses optimal experimental designs for estimating the model parameters or other characteristics of the pH-profile. Section 4 gives some numerical illustrations of designs that are optimal or that are derived from the optimal design by taking practicability into account. In the final section, recommendations are given for the practical use of the suggested designs. (author's abstract)Series: Forschungsberichte / Institut für Statisti

Forecasting with Optimized Moving Local Regression

This paper empirically demonstrates the relative merits of the optimal choice of the weight function in a moving local regression as suggested by Fedorov et al., (1993) over traditional weight functions which ignore the form of the local model. The discussion is based on a task that is imbedded into the smoothing methodology, namely the forecasting of business time series data with the help of a one-sided moving local regression model. (author's abstract)Series: Forschungsberichte / Institut für Statisti

An Oxygen-Permeable Bilayer MIEC-Redox Membrane Concept

Mixed ionic-electronic conducting (MIEC) membranes attract the attention because of their high potential for oxygen separation and energy conversion applications. The different fabrication methods of asymmetric membranes consisting of a thin MIEC layer on porous support were developed. The basically dense but not completely hermetic thin layers were achieved. To overcome this problem, we suggest a new concept of bilayer MIEC-Redox membrane. This solid/liquid composite membrane consists of a gastight MIEC thin external layer and a thick internal layer in which the redox reactions and oxygen bubbling occur. Here, we report the transport properties of a copper oxide-based MIEC-Redox membrane