Algorithmic commonalities in the parallel environment

The ultimate aim of this project was to analyze procedures from substantially different application areas to discover what is either common or peculiar in the process of conversion to the Massively Parallel Processor (MPP). Three areas were identified: molecular dynamic simulation, production systems (rule systems), and various graphics and vision algorithms. To date, only selected graphics procedures have been investigated. They are the most readily available, and produce the most visible results. These include simple polygon patch rendering, raycasting against a constructive solid geometric model, and stochastic or fractal based textured surface algorithms. Only the simplest of conversion strategies, mapping a major loop to the array, has been investigated so far. It is not entirely satisfactory

The Development of a Paper-and-Pencil Measure of Complex Cognitive-Perceptual Aptitude

The primary purpose of the present research was a develop a complex aptitude test to assess individual differences in multiple cognitive and perceptual abilities that are required for helicopter pilot training. The paper-and-pencil test was designed to provide measures of both static and dynamic (i.e., learning) ability under different levels of complexity. The secondary research purpose was to develop a battery of eight psychometric tests to assess other abilities that are required for helicopter pilot training. Test prototypes were produced and administered to small samples of subjects. The tests were then revised into an experimental battery that required approximately 7 hours to administer. The battery was administered to 290 subjects at three military bases, but 17 subjects were deleted from the analyses for not providing complete data, not following test procedures, etc. Performance on the battery by the remaining 273 subjects is considered to be representative of the abilities that exist among military personnel during the training stage of their careers. The psychometric characteristics of most of the tests justify further research on their utility as selection instruments. The average difficulty levels are near the optimum level of .50, the test variances indicate the measurement of substantial individual differences, and the estimates of reliability are acceptable when test length and design specifications are considered. Factor analyses indicate that the battery assesses seven independent dimensions of human abilities. When the test sections are combined into total scores, the battery assesses three primary ability domains: cognitive-perceptual, perceptual speed, and spatial orientation. Corrections for guessing did not substantially alter the underlying factor structure of the battery. Two additional factors were extracted when the within-difficulty-level gain scores from the complex test were included in the total score analysis. The gain scores at the lower difficulty level are interpreted to be indices of learning while the gain scores at the higher difficulty level are interpreted to be indices of fatigue. It was concluded that the complex test and six of the psychometric tests assess reliable individual differences in the abilities of interest

Report from the MPP Working Group to the NASA Associate Administrator for Space Science and Applications

NASA's Office of Space Science and Applications (OSSA) gave a select group of scientists the opportunity to test and implement their computational algorithms on the Massively Parallel Processor (MPP) located at Goddard Space Flight Center, beginning in late 1985. One year later, the Working Group presented its report, which addressed the following: algorithms, programming languages, architecture, programming environments, the way theory relates, and performance measured. The findings point to a number of demonstrated computational techniques for which the MPP architecture is ideally suited. For example, besides executing much faster on the MPP than on conventional computers, systolic VLSI simulation (where distances are short), lattice simulation, neural network simulation, and image problems were found to be easier to program on the MPP's architecture than on a CYBER 205 or even a VAX. The report also makes technical recommendations covering all aspects of MPP use, and recommendations concerning the future of the MPP and machines based on similar architectures, expansion of the Working Group, and study of the role of future parallel processors for space station, EOS, and the Great Observatories era

PDGF-BB does not accelerate healing in diabetic mice with splinted skin wounds.

Topical application of platelet-derived growth factor-BB (PDGF-BB) is considered to accelerate tissue repair of impaired chronic wounds. However, the vast literature is plagued with conflicting reports of its efficacy in animal models and this is often influenced by a wide array of experimental variables making it difficult to compare the results across the studies. To mitigate the confounding variables that influence the efficacy of topically applied PDGF-BB, we used a controlled full thickness splinted excisional wound model in db/db mice (type 2 diabetic mouse model) for our investigations. A carefully-defined silicone-splinted wound model, with reduced wound contraction, controlled splint and bandage maintenance, allowing for healing primarily by reepithelialization was employed. Two splinted 8 mm dorsal full thickness wounds were made in db/db mice. Wounds were topically treated once daily with either 3 µg PDGF-BB in 30 µl of 5% PEG-PBS vehicle or an equal volume of vehicle for 10 days. Body weights, wound contraction, wound closure, reepithelialization, collagen content, and wound bed inflammation were evaluated clinically and histopathologically. The bioactivity of PDGF-BB was confirmed by in vitro proliferation assay. PDGF-BB, although bioactive in vitro, failed to accelerate wound healing in vivo in the db/db mice using the splinted wound model. Considering that the predominant mechanism of wound healing in humans is by re-epithelialization, the most appropriate model for evaluating therapeutics is one that uses splints to prevent excessive wound contraction. Here, we report that PDGF-BB does not promote wound closure by re-epithelialization in a murine splinted wound model. Our results highlight that the effects of cytoactive factors reported in vivo ought to be carefully interpreted with critical consideration of the wound model used

Pilot Based Spacing and Separation on Approach to Landing: The Effect on Air Traffic Controller Workload and Performance

This document summarizes the existing literature on workload and performance issues related to pilot-based spacing and separation, methods under investigation for managing increases in traffic. Multiple concepts are under development, all of which involve pilot use of a Cockpit Display of Traffic Information (CDTI) that presents data about nearby traffic (e.g., location, altitude). More advanced CDTIs include functions that alert the pilot to potential conflicts or provide guidance about flight paths or speeds. This document focuses on concepts proposed for use during sequencing and merging and on final approach. Some concepts are considered more basic in that they would involve little change to current procedures and require only basic CDTI functionality. The literature indicates that pilot use of a basic CDTI to assist in visually acquiring traffic and following a lead aircraft is beneficial, and that pilot workload is generally acceptable. Controller reaction to pilot use of the CDTI for these purposes has also been generally positive. More advanced concepts that involve the use of more sophisticated CDTI functions require modifications to current procedures and additional controller workstation tools. The results from most studies indicate that the advanced concepts require further development before they become operationally feasible. 17

Recommended Layouts for the En Route Area Supervisor Work Space

Over the past decade, the Supervisor Work Space (SWS) at Air Route Traffic Control Centers (ARTCCs) has evolved to include as many as eight computer-based systems and other legacy equipment, paper reference materials, and supplies. Researchers from the Federal Aviation Administration Human Factors (HF) Team surveyed supervisors regarding equipment usage, location, and placement issues. Supervisors from 20 ARTCCs responded. The supervisors reported using computer systems approximately 50% of the time during a typical shift. They noted that their work spaces were cluttered, that placement of some systems made it difficult to see monitors or to access input devices, and that it was difficult to maintain the equipment. The HF researchers identified two common SWS layouts: (a) one layout in which the supervisor was seated in the main aisle looking into the operations area and (b) an alternate layout in which the supervisor was seated inside the operations area. The researchers developed baseline virtual reality models of the SWS based on HF guidelines and satisfactory aspects of existing work spaces. A working group of operational supervisors reviewed the baseline models and developed recommended layouts for the exterior, interior, and centralized command models of the en route area SWS

Effects of Collocation and Reduced Lateral Separation Standards in the New York integrated Control Complex

The authors used a high fidelity, human-in-the-loop simulation in two experiments examining the concept of the New York Integrated Control Complex (NYICC). The first experiment examined the potential effects of collocation alone and collocation with expanded terminal separation standards on the arrival traffic flow into Newark. The second experiment examined the same effects on the departure traffic flows primarily from Newark International (EWR) and LaGuardia (LGA) airports. Each experiment compared three different conditions. In the Normal condition, the participants controlled traffic as they normally would, and a removable wall physically separated the terminal and en route sectors. During the Collocated condition, experimenters removed the wall, and the participants could engage in face-to-face communication and look at each other\u2019s radar displays. During the Terminalized condition, we collocated the sectors and reduced the separation standard for one or both en route sectors from 5 nm to 3 nm. We collected measures throughout the experiments including system performance, subjective ratings of workload, subject matter expert ratings of performance, communication behaviors, and participant opinion. Overall, both experiments provided support for the NYICC concept of operations. Sponsor FAA Eastern Region Air Traffic Division Airspace Branch, Jamaica, New Yor

Human-in-the-Loop Evaluation of An integrated Arrival/Departure Air Traffic Control Service for Major Metropolitan Airspaces

Abstract The increasing number of U.S. air flights has placed a severe strain on the National Airspace System (NAS), especially airspace surrounding major metropolitan areas. In a recent study, Truitt, McAnulty, and Willems (2004) tested and found benefits in procedures designed to address some of the pressures around New York airspace. The procedures included extending terminal lateral separation standards (3 nm) and procedures (diverging courses) into en route airspace as well as collocating terminal and en route facilities to promote more effective communication and coordination. The Integrated Arrival/Departure Air Traffic Control Service, termed the Big Airspace (BA) concept, applies these procedures to other busy areas and includes the use of Area Navigation(RNAV) routes as well as dynamic resectorization to make airspace boundaries more flexible. Twenty-four controllers from en route and terminal facilities participated in a simulation that compared a baseline (BL) condition using current airspace standards and procedures to two BA conditions. In one condition, en route and terminal participants managed traffic in the same control room, and in the other condition they worked as if in separate facilities. Overall, the results provided support for the BA concept. The aircraft moved through the arrival corridor more efficiently in the BA conditions than in the BL condition, and participants made fewer ground-ground transmissions and issued fewer altitude and heading clearances. Subjective ratings of performance, situation awareness, and the ability to move traffic through the sector were also higher in the BA conditions

Human Factors Assessment of the En Route Information Display System

Human factors researchers at the Federal Aviation Administration have developed new methods of operation for Air Traffic Control Specialists working in Airport Traffic Control Towers (ATCT). The newly redesigned and enhanced Tower Operations Digital Data System (TODDS) provides a means to assist ATCT controllers with flight data management, communication, and coordination by reducing cognitive and physical task load. The TODDS prototype designs include separate solutions for ATCTs either with or without surface surveillance capability. This report addresses the results of a recent usability test by providing a description of design changes and new features that compose the TODDS. The author also recommends the use of a touchscreen training protocol. Pending further investigation, the TODDS may help reduce the risk of runway incursions, ease the flow of surface operations, and support the Staffed Virtual Tower concept

Ventricular pacing or dual-chamber pacing for sinus-node dysfunction

BACKGROUND Dual-chamber (atrioventricular) and single-chamber (ventricular) pacing are alternative treatment approaches for sinus-node dysfunction that causes clinically significant bradycardia. However, it is unknown which type of pacing results in the better outcome. METHODS We randomly assigned a total of 2010 patients with sinus-node dysfunction to dual-chamber pacing (1014 patients) or ventricular pacing (996 patients) and followed them for a median of 33.1 months. The primary end point was death from any cause or nonfatal stroke. Secondary end points included the composite of death, stroke, or hospitalization for heart failure; atrial fibrillation; heart-failure score; the pacemaker syndrome; and the quality of life. RESULTS The incidence of the primary end point did not differ significantly between the dual-chamber group (21.5 percent) and the ventricular-paced group (23.0 percent, P=0.48). In patients assigned to dual-chamber pacing, the risk of atrial fibrillation was lower (hazard ratio, 0.79; 95 percent confidence interval, 0.66 to 0.94; P=0.008), and heart-failure scores were better (P CONCLUSIONS In sinus-node dysfunction, dual-chamber pacing does not improve stroke-free survival, as compared with ventricular pacing. However, dual-chamber pacing reduces the risk of atrial fibrillation, reduces signs and symptoms of heart failure, and slightly improves the quality of life. Overall, dual-chamber pacing offers significant improvement as compared with ventricular pacing