What bandwidth do I need for my image?

Computer representations of real numbers are necessarily discrete, with some finite resolution, discreteness, quantization, or minimum representable difference. We perform astrometric and photometric measurements on stars and co-add multiple observations of faint sources to demonstrate that essentially all of the scientific information in an optical astronomical image can be preserved or transmitted when the minimum representable difference is a factor of two finer than the root-variance of the per-pixel noise. Adopting a representation this coarse reduces bandwidth for data acquisition, transmission, or storage, or permits better use of the system dynamic range, without sacrificing any information for down-stream data analysis, including information on sources fainter than the minimum representable difference itself.Comment: submitted to PAS

Mass and power modeling of communication satellites

Analytic estimating relationships for the mass and power requirements for major satellite subsystems are described. The model for each subsystem is keyed to the performance drivers and system requirements that influence their selection and use. Guidelines are also given for choosing among alternative technologies which accounts for other significant variables such as cost, risk, schedule, operations, heritage, and life requirements. These models are intended for application to first order systems analyses, where resources do not warrant detailed development of a communications system scenario. Given this ground rule, the models are simplified to 'smoothed' representation of reality. Therefore, the user is cautioned that cost, schedule, and risk may be significantly impacted where interpolations are sufficiently different from existing hardware as to warrant development of new devices

Assessing the clinical value of fast onset and sustained duration of action of long-acting bronchodilators for COPD

Date of Aceptance: 12/02/2015 Acknowledgments The authors were assisted in the preparation of the manuscript by Sarah Filcek, a professional medical writer at CircleScience (Tytherington, UK), part of KnowledgePoint360, an Ashfield Company. This assistance was funded by Novartis Pharmaceuticals. Copyright © 2015. Published by Elsevier Ltd.Peer reviewedPublisher PD

The Lion Looks West: Change in the Welsh Marches During the Last Half of the Eleventh Century

The change with the coming of the Normans to the Welsh Marches was not as encompassing as scholarship indicates, based on primary source analysis. Castles and leadership in the Welsh Marches did indeed change, yet the economy continued to be fluid and semblances of nationalism scholars attribute to the last half of the eleventh century have been distorted. While a glimpse of the countryside and a history book will shout the word CASTLES , there is more to the Norman arrival, to the people who lived in the region of the Welsh Marches, and to the Welsh, than simply the construction of new castles. Aspects such as the day to day lives of the inhabitants, the economic impact, the social structure, and the concept of nationalism in the Welsh Marches cannot be assumed to change based only upon the concept that with new overlords comes change to all aspects of life. The relevance of this endeavor is to better understand life in the Welsh Marches rather than attach the epithet change to what occurred with the arrival of the Normans, accomplished through analysis of surviving chronicles and administrative records as well as current scholarship done on the region

The responses of small and large firms to tight credit shocks : the case of 2008 through the lens of Gertler and Gilchrist (1994)

Do large firms and small firms behave differently when credit becomes more costly or harder to obtain? Past research has found that small firms are more likely to be credit-constrained and thus tend to be affected more negatively than large firms during such times. Recent findings from the 2007-2009 recession, however, raise questions about the roles of small and large firms during periods of tight creditBusiness cycles ; Recessions

Full-Potential LMTO: Total Energy and Force Calculations

The essential features of a full potential electronic structure method using Linear Muffin-Tin Orbitals (LMTOs) are presented. The electron density and potential in the this method are represented with no inherent geometrical approximation. This method allows the calculation of total energies and forces with arbitrary accuracy while sacrificing much of the efficiency and physical content of approximate methods such as the LMTO-ASA method.Comment: 25 pages, 2 figures, Workshop on the TB-LMTO method, Monastery of Mont St. Odile, October 4-5, 199

Modelling circumstellar discs with 3D radiation hydrodynamics

We present results from combining a grid-based radiative transfer code with a Smoothed Particle Hydrodynamics code to produce a flexible system for modelling radiation hydrodynamics. We use a benchmark model of a circumstellar disc to determine a robust method for constructing a gridded density distribution from SPH particles. The benchmark disc is then used to determine the accuracy of the radiative transfer results. We find that the SED and the temperature distribution within the disc are sensitive to the representation of the disc inner edge, which depends critically on both the grid and SPH resolution. The code is then used to model a circumstellar disc around a T-Tauri star. As the disc adjusts towards equilibrium vertical motions in the disc are induced resulting in scale height enhancements which intercept radiation from the central star. Vertical transport of radiation enables these perturbations to influence the mid-plane temperature of the disc. The vertical motions decay over time and the disc ultimately reaches a state of simultaneous hydrostatic and radiative equilibrium.Comment: MNRAS accepted; 15 pages; 17 figures, 4 in colou