Modelling solar low-lying cool loops with optically thick radiative losses

We investigate the increase of the DEM (differential emission measure) towards the chromosphere due to small and cool magnetic loops (height $\lesssim8$~Mm, $T\lesssim10^5$~K). In a previous paper we analysed the conditions of existence and stability of these loops through hydrodynamic simulations, focusing on their dependence on the details of the optically thin radiative loss function used. In this paper, we extend those hydrodynamic simulations to verify if this class of loops exists and it is stable when using an optically thick radiative loss function. We study two cases: constant background heating and a heating depending on the density. The contribution to the transition region EUV output of these loops is also calculated and presented. We find that stable, quasi-static cool loops can be obtained by using an optically thick radiative loss function and a background heating depending on the density. The DEMs of these loops, however, fail to reproduce the observed DEM for temperatures between $4.6<\log T<4.8$. We also show the transient phase of a dynamic loop obtained by considering constant heating rate and find that its average DEM, interpreted as a set of evolving dynamic loops, reproduces quite well the observed DEM.Comment: Accepted for publication in A&A on Aug 21st 2015. arXiv admin note: text overlap with arXiv:1112.030

MEASURING OFFICE COMPLEXITY

An "office" can be described in terms of at least four different (but related) sets of descriptors: the physical, the social, the organizational, and the work-related. This paper focuses on work-related aspects of offices, and presents two measures of complexity in office work. The first measure, operational complexity, gauges the average difficulty, in terms of the cognitive resources required, to perform a "chunk" of office work. Independent of this, sequential complexity measures the potential number of task sequences which could be used to accomplish a given chunk of work. Sequential complexity increases as does the number of "special cases," "special cases of special cases," etc. for which the chunk of office work need be performed. In other words, it focuses on the complexity of interrelationships between individual office tasks, while operational complexity is concerned with the complexity of the individual tasks themselves. We then combine these measures into a an aggregate measure of overall complexity, combined complexity. The application of these measures is illustrated, using descriptions of order entry processes, for two hypothetical firms, employing job shop and assembly-line technologies, respectively. While these three measures hardly comprise an exhaustive catalogue of complexity in the "office" (or even in office work), we believe they provide a useful basis for both practical application and further theoretical extension.Information Systems Working Papers Serie

Architectures for Financial Consolidation: A Comparative Study

Although financial consolidation systems may share such similar components as algorithms and data structures, many systems designers are unfamiliar with the corresponding attributes of different consolidation architectures. As a result, some designers fail to select the best consolidation architecture for their clients. This article examines and analyzes corporate financial consolidation in five firms and illustrates how to match the correct system to the organizational structure of your firm.Information Systems Working Papers Serie

MAPPING OFFICE WORK TO OFFICE TECHNOLOGY

have achieved success with respect to describing what happens in the office, they have contributed far less with respect to prescribing how computer-based technologies can support the office. Here we present TEMO (TEchnological Mapping of Office-work), a procedure which aids the analyst in determining the feasibility of supporting a given office task and suggests which specific software packages might improve performance of that task. In order to illustrate the procedure's application, we present a case in which TEMO is applied, in step-by-step fashion, in order to assess the feasibility of automating a simple set of tasks and to assist in the selection of an appropriate software package. Directions of continuing work in the procedure's extension, enhancement, and evaluation are also described.Information Systems Working Papers Serie

CONSTRUCTIVE IMAGES AND DIAGRAMS: THEIR ROLE IN INFORMATION SYSTEMS DEVELOPMENT

In order to promote more creative solutions to Information Systems (IS) design problems, this paper identifies four roles that images or diagrams can play in the IS development process. These roles are characteristics of the interaction between the image and its creator or viewer, rather than of the diagram itself. One of these roles in particular, the constructive role, can do much to support the generation of creative designs, to the benefit of both systems developers and their clients. The goal of constructive systems thinking is to enhance the creative solution of IS development problems, and it cannot be reduced to a specific, highly structured technique. We can, however, outline a general approach to building constructive images: 1. Create a set of candidate analogies, elaborate them, and evaluate the degree to which each guides design of the target system. 2. Evaluate how completely this working set of analogies in forms the important aspects of the target system, and create additional analogies to fill any major gaps. 3. Over the relevant scope of each analogy, research its structure and dynamic interactions. Use these as templates within which to model the target system. 4. Validate this design and its functional implications with the system client, adjusting it as required. 5. Complete the design by removing details specific to the analogous system and adding those relevant to the target system.Information Systems Working Papers Serie

Lumbar extraforaminal decompression: A technical note and retrospective study looking at potential complications as an outpatient procedure

BACKGROUND: Lumbar disc herniation and stenosis that results in compression of a nerve root lateral to the foramen is defined as extraforaminal. In recent years the recognition of such pathology has increased with technology and greater awareness. Various approaches and techniques have been developed for extraforaminal decompression in the lumbar region. The purpose of this study was two fold: 1) Determine the safety of treating patients operatively via a paramedian muscle splitting approach on an outpatient basis, and 2) Highlight the technical aspects of the approach to the extraforaminal region. METHODS: One hundred consecutive extraforaminal decompressions were performed from 1992 to 2007 by a single surgeon. A retrospective review was performed consisting of chart reviews. Summary statistics and the Pierson Chi-square test were used to analyze the data. The primary outcome measure was the need for hospital admission or readmission following surgical decompression. RESULTS: Seven of 100 patients (7%) were required to remain in the hospital for twenty-three hour observation due to Medicare requirements. Five (5%) of the patients originally scheduled for an outpatient procedure were converted to inpatient status due to postoperative pain. All were released within 2 days (average 1.25 days). Only one (1%) patient was readmitted for urinary retention that resolved without incident. There was no significant difference (P = 0.137) in complication rate between our control and those that underwent extraforaminal decompression. CONCLUSIONS: Extraforaminal lumbar decompression as an outpatient procedure can be done safely without the need for hospital admission

Paper Session II-A - Lockheed Martin\u27s Next Generation Launch Systems

The space launch industry is experiencing a tremendous transition from a government dominated customer base to a commercial customer base. According to the Teal Group World Space Briefing, nearly 75 percent of satellites launched from 1997 to 2006 will be civil and commercial satellites (figure 1). Of these, the vast majority are commercial ventures in mobile communications, broadband multi-media services, or direct broadcast television satellites. Nearly three quarters of all proposed payloads are destined for Low Earth Orbit (LEO). Virtually all LEO satellites will belong to multi-satellite systems involving mobile communications or multimedia services. Lockheed Martin is a world leader in the expendable launch vehicle industry. Our heritage which began with the Titan and Atlas launch systems in the late 1950’s, has spanned four decades and over 1,000 launches. In the late 1980’s, the former General Dynamics Space Systems (GD), recognized the need to develop a launch vehicle that could compete in the international commercial market. In 1987, GDinitiated the first commercial launch vehicle, the Atlas II. TheAtlas vehicle has successfully evolved from II to IIA to IIAS and into today’s newest most powerful system yet - the Atlas IIAR which will be operational in late 1998. The driving force behind each system upgrade has been to improve performance while reducing cost and increasing reliability. Lockheed Martin combined the commercial industry expertise of the Atlas program with the heritage hardware of both the Atlas and Titan programs to develop their next generation launch vehicle the Common Core BoosterTM family. The Common Core BoosterTM family of launch vehicles will accommodate a wide range of customers, by providing a highly reliable, responsive system with streamlined launch operations. The Common Core BoosterTM vehicle allows Lockheed Martin tol effectively compete in international commercial markets, while satisfying the United States government requirements for low cost, reliable access to space. The purpose of this paper is to describe Lockheed Martin’s approach to incorporating the benefits and lessons learned from the Atlas and Titan launch systems into a launch vehicle family that will serve the payload community well into the 21st Century

Wavefront errors in a two-beam interferometer

This paper deals with the impact of wavefront errors, due to the optical aberrations of a two-beam interferometer, on the period of the travelling fringe observed by integrating the interference pattern. A Monte Carlo simulation of the interferometer operation showed that the fringe-period estimate is unbiased if evaluated on the basis of the angular spectrum of the beam entering the interferometer, but the wavefront errors increase the uncertainty

Forward scattering in two-beam laser interferometry

A fractional error as large as 25 pm mm(-1) at the zero optical-path difference has been observed in an optical interferometer measuring the displacement of an x-ray interferometer used to determine the lattice parameter of silicon. Detailed investigations have brought to light that the error was caused by light forward-scattered from the beam feeding the interferometer. This paper reports on the impact of forward-scattered light on the accuracy of two-beam optical interferometry applied to length metrology, and supplies a model capable of explaining the observed error