Optimal pricing using online auction experiments: A P\'olya tree approach

We show how a retailer can estimate the optimal price of a new product using observed transaction prices from online second-price auction experiments. For this purpose we propose a Bayesian P\'olya tree approach which, given the limited nature of the data, requires a specially tailored implementation. Avoiding the need for a priori parametric assumptions, the P\'olya tree approach allows for flexible inference of the valuation distribution, leading to more robust estimation of optimal price than competing parametric approaches. In collaboration with an online jewelry retailer, we illustrate how our methodology can be combined with managerial prior knowledge to estimate the profit maximizing price of a new jewelry product.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS503 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Predicted percentage dissatisfied with vertical temperature gradient

A vertical thermally stratified environment provides opportunities for improved ventilation effectiveness and energy efficiency, but vertical temperature gradient can also cause local thermal discomfort. ASHRAE 55 and ISO 7730 prescribe a 3 °C/m limit between head and feet for seated persons. However, an increasing amount of evidence suggests that this limit is too restrictive. To revisit how vertical temperature gradient affects local thermal comfort, we conducted laboratory tests with four nominal vertical temperature gradients (0.4, 2.9, 5.9, and 8.4 °C/m). Ninety-eight seated college-age students participated in a blind within-subject experiment. Cold-feet discomfort is more frequently rated than warm-head discomfort with increasing temperature gradients. By using logistic regression modeling, we show that the whole-body dissatisfaction increases only slightly (< 10 %) with vertical temperature gradient, even up to 8.4 °C/m. Sex does not significantly affect the results except at 8.4 °C/m. Acceptable vertical temperature gradient changes with thermal sensation votes. The results suggest that the vertical temperature gradient could be increased to 5 °C/m between head and feet when the subject is thermally neutral

Biology and pathophysiology of the amyloid precursor protein

The amyloid precursor protein (APP) plays a central role in the pathophysiology of Alzheimer's disease in large part due to the sequential proteolytic cleavages that result in the generation of β-amyloid peptides (Aβ). Not surprisingly, the biological properties of APP have also been the subject of great interest and intense investigations. Since our 2006 review, the body of literature on APP continues to expand, thereby offering further insights into the biochemical, cellular and functional properties of this interesting molecule. Sophisticated mouse models have been created to allow in vivo examination of cell type-specific functions of APP together with the many functional domains. This review provides an overview and update on our current understanding of the pathobiology of APP

The amyloid precursor protein: beyond amyloid

The amyloid precursor protein (APP) takes a central position in Alzheimer's disease (AD) pathogenesis: APP processing generates the β-amyloid (Aβ) peptides, which are deposited as the amyloid plaques in brains of AD individuals; Point mutations and duplications of APP are causal for a subset of early onset of familial Alzheimer's disease (FAD). Not surprisingly, the production and pathogenic effect of Aβ has been the central focus in AD field. Nevertheless, the biological properties of APP have also been the subject of intense investigation since its identification nearly 20 years ago as it demonstrates a number of interesting putative physiological roles. Several attractive models of APP function have been put forward recently based on in vitro biochemical studies. Genetic analyses of gain- and loss-of-function mutants in Drosophila and mouse have also revealed important insights into its biological activities in vivo. This article will review the current understanding of APP physiological functions

Optimising superoscillatory spots for far-field super-resolution imaging

Optical superoscillatory imaging, allowing unlabelled far-field super-resolution, has in recent years become reality. Instruments have been built and their super-resolution imaging capabilities demonstrated. The question is no longer whether this can be done, but how well: what resolution is practically achievable? Numerous works have optimised various particular features of superoscillatory spots, but in order to probe the limits of superoscillatory imaging we need to simultaneously optimise all the important spot features: those that define the resolution of the system. We simultaneously optimise spot size and its intensity relative to the sidebands for various fields of view, giving a set of best compromises for use in different imaging scenarios. Our technique uses the circular prolate spheroidal wave functions as a basis set on the field of view, and the optimal combination of these, representing the optimal spot, is found using a multi-objective genetic algorithm. We then introduce a less computationally demanding approach suitable for real-time use in the laboratory which, crucially, allows independent control of spot size and field of view. Imaging simulations demonstrate the resolution achievable with these spots. We show a three-order-of-magnitude improvement in the efficiency of focusing to achieve the same resolution as previously reported results, or a 26 % increase in resolution for the same efficiency of focusing

Barriers to Implementing Large-Scale Online Staff Development Programs for Teachers

This is the publisher's version, which may also be found here: http://www.westga.edu/~distance/ojdla/winter64/meyen64.pdfThis study on barriers to online staff development for classroom teachers was conducted as part of the planning activities of a delivery models project designed to develop guidelines for implementing large-scale online staff development programs. The study involved engaging 54 general and special educators in several professional roles from nine states in a series of focus groups to identify the barriers to online staff development. An instrument was designed to rank order the barriers in terms of perceived significance. Twenty-two barriers were identified. This project was in follow-up to the Online Academy (H029K73002) funded by the Office of Special Education Programs in the U.S. Department of Education (OSEP/USDOE)

Advances to ASHRAE Standard 55 to encourage more effective building practice

ASHRAE Standard 55 has been evolving in recent years to encourage more sustainable building designs and operational practices. A series of changes address issues for which past design practice has been deficient or overly constrained. Some of the changes were enabled by findings from field studies of comfort and energy-efficiency, and others by new developments in the design- and building-management professions.  The changes have been influencing practice and spurring follow-on research.The Standard now addresses effects of elevated air movement, solar gain on the occupant, and draft at the ankles, each with several impacts on energy-efficient design and operation. It also addresses the most important source of discomfort in modern buildings, the large inter- and intra-personal variability in thermal comfort requirements, by classifying the occupants’ personal control and adaptive options in a form that can be used in building rating systems. In order to facilitate design, new computer tools extend the use of the standard toward direct use in designers’ workflow. The standard also includes provisions for monitoring and evaluating buildings in operation. This paper summarizes these developments and their underlying research, and attempts to look ahead

Effect of inhomogeneities on the expansion rate of the Universe

While the expansion rate of a homogeneous isotropic Universe is simply proportional to the square-root of the energy density, the expansion rate of an inhomogeneous Universe also depends on the nature of the density inhomogeneities. In this paper we calculate to second order in perturbation variables the expansion rate of an inhomogeneous Universe and demonstrate corrections to the evolution of the expansion rate. While we find that the mean correction is small, the variance of the correction on the scale of the Hubble radius is sensitive to the physical significance of the unknown spectrum of density perturbations beyond the Hubble radius.Comment: 19 pages, 2 figures Version 2 includes some changes in numerical factors and corrected typos. It is the version accepted for publication in Physical review

Machine-Learning Dessins d'Enfants: Explorations via Modular and Seiberg-Witten Curves

We apply machine-learning to the study of dessins d'enfants. Specifically, we investigate a class of dessins which reside at the intersection of the investigations of modular subgroups, Seiberg-Witten curves and extremal elliptic K3 surfaces. A deep feed-forward neural network with simple structure and standard activation functions without prior knowledge of the underlying mathematics is established and imposed onto the classification of extension degree over the rationals, known to be a difficult problem. The classifications reached 0.92 accuracy with 0.03 standard error relatively quickly. The Seiberg-Witten curves for those with rational coefficients are also tabulated.Comment: 60 pages, 197 figures. Acknowledgements updated to reflect thanks to the group at UoAugsburg for highlighting a data analysis problem, that lead authors to identify the dessin d'enfant representation subtlety and use the improved cyclic edge list representation, as in version