Sunmaster: An SEP cargo vehicle for Mars missions

Options are examined for an unmanned solar powered electric propulsion cargo vehicle for Mars missions. The 6 prime areas of study include: trajectory, propulsion system, power system, supporting structure, control system, and launch consideration. Optimization of the low thrust trajectory resulted in a total round trip mission time just under 4 years. The argon propelled electrostatic ion thruster system consists of seventeen 5 N engines and uses a specific impulse of 10,300 secs. At Earth, the system uses 13 engines to produce 60 N of thrust; at Mars, five engines are used, producing 25 N thrust. The thrust of the craft is varied between 60 N at Earth and 24 N at Mars due to reduced solar power available. Solar power is collected by a Fresnel lens concentrator system using a multistacked cell. This system provides 3.5 MW to the propulsion system after losses. Control and positioning to the craft are provided by a system of three double gimballed control moment gyros. Four shuttle 'C' launches will be used to transport the unassembled vehicle in modular units to low Earth orbit where it will be assembled using the Mobile Transporter of the Space Station Freedom

On Energy-efficient Checkpointing in High-throughput Cycle-stealing Distributed Systems

Checkpointing is a fault-tolerance mechanism commonly used in High Throughput Computing (HTC) environments to allow the execution of long-running computational tasks on compute resources subject to hardware and software failures and interruptions from resource owners. With increasing scrutiny of the energy consumption of IT infrastructures, it is important to understand the impact of checkpointing on the energy consumption of HTC environments. In this paper we demonstrate through trace-driven simulation on real-world datasets that existing checkpointing strategies are inadequate at maintaining an acceptable level of energy consumption whilst reducing the makespan of tasks. Furthermore, we identify factors important in deciding whether to employ checkpointing within an HTC environment, and propose novel strategies to curtail the energy consumption of checkpointing approaches

Outlook and appraisal [March 1993]

The end of the recession is at hand, but the size and timing of proposed tax increases may limit the speed of recovery and so reduce further the prospects for the three million unemployed in Britain

Outlook and appraisal [June 1993]

First quarter GDP figures signal the end of the recession. Recent falls in unemployment and rising house prices should stimulate greater expenditure from consumers now that the threat of redundancy has receded

The Scottish economy [March 1993]

Our previous forecast of a small fall in the seasonally adjusted output index for Scottish production industries (Divisions 1 to 4 of the 1980 SIC) for the third quarter last year was not borne out by the actual outcome. This is mainly due to a large under-reporting of the index for the second quarter last year in the previous official data release. It is now clear that the prolonged recession, and particularly the substantial fall in output in the second quarter contributed significantly to the deterioration of business confidence as reported in the previous Scottish Chambers' business surveys (which should also affect the early official recording of the second quarter's output). This under-reporting leads our model to predict a further fall, although small, in the following quarter. However, the actual outcome of industrial output, total volume of sales and new orders in the third quarter turned out to be not as bad as we had been expecting (see also the following business survey section). Nevertheless, as data reveal in this paper, we are expecting a large fall in production for 1992 as a whole. There will be a further marked reduction in Scottish industrial output

Special article : Quarterly Economic Commentary: Volume 10-18

The Fraser ofAllander Institute has, since its inception, sought to promote debate and research into the Scottish economy. One way in which we have done this is to publish, every quarter, a collection of views and results from those who conduct research in this area. In the current volume J McGilvray presents a review of the responses to the government's consultation paper on water and sewerage in Scotland. In previous volumes, a large number of articles appeared and addressed a wide variety of subjects. Articles which appeared in volumes 10 - 18 are documented on the following pages and those wishing to obtain backcopies can do so, through the Institute, by contacting the editor. Articles appear by volume & number and are labelled according to whether they were a Feature Article (FA), Briefing Paper (BP), Economic Perspective (EP) or a Special Article (SA

Analysis of shared heritability in common disorders of the brain

ience, this issue p. eaap8757 Structured Abstract INTRODUCTION Brain disorders may exhibit shared symptoms and substantial epidemiological comorbidity, inciting debate about their etiologic overlap. However, detailed study of phenotypes with different ages of onset, severity, and presentation poses a considerable challenge. Recently developed heritability methods allow us to accurately measure correlation of genome-wide common variant risk between two phenotypes from pools of different individuals and assess how connected they, or at least their genetic risks, are on the genomic level. We used genome-wide association data for 265,218 patients and 784,643 control participants, as well as 17 phenotypes from a total of 1,191,588 individuals, to quantify the degree of overlap for genetic risk factors of 25 common brain disorders. RATIONALE Over the past century, the classification of brain disorders has evolved to reflect the medical and scientific communities' assessments of the presumed root causes of clinical phenomena such as behavioral change, loss of motor function, or alterations of consciousness. Directly observable phenomena (such as the presence of emboli, protein tangles, or unusual electrical activity patterns) generally define and separate neurological disorders from psychiatric disorders. Understanding the genetic underpinnings and categorical distinctions for brain disorders and related phenotypes may inform the search for their biological mechanisms. RESULTS Common variant risk for psychiatric disorders was shown to correlate significantly, especially among attention deficit hyperactivity disorder (ADHD), bipolar disorder, major depressive disorder (MDD), and schizophrenia. By contrast, neurological disorders appear more distinct from one another and from the psychiatric disorders, except for migraine, which was significantly correlated to ADHD, MDD, and Tourette syndrome. We demonstrate that, in the general population, the personality trait neuroticism is significantly correlated with almost every psychiatric disorder and migraine. We also identify significant genetic sharing between disorders and early life cognitive measures (e.g., years of education and college attainment) in the general population, demonstrating positive correlation with several psychiatric disorders (e.g., anorexia nervosa and bipolar disorder) and negative correlation with several neurological phenotypes (e.g., Alzheimer's disease and ischemic stroke), even though the latter are considered to result from specific processes that occur later in life. Extensive simulations were also performed to inform how statistical power, diagnostic misclassification, and phenotypic heterogeneity influence genetic correlations. CONCLUSION The high degree of genetic correlation among many of the psychiatric disorders adds further evidence that their current clinical boundaries do not reflect distinct underlying pathogenic processes, at least on the genetic level. This suggests a deeply interconnected nature for psychiatric disorders, in contrast to neurological disorders, and underscores the need to refine psychiatric diagnostics. Genetically informed analyses may provide important "scaffolding" to support such restructuring of psychiatric nosology, which likely requires incorporating many levels of information. By contrast, we find limited evidence for widespread common genetic risk sharing among neurological disorders or across neurological and psychiatric disorders. We show that both psychiatric and neurological disorders have robust correlations with cognitive and personality measures. Further study is needed to evaluate whether overlapping genetic contributions to psychiatric pathology may influence treatment choices. Ultimately, such developments may pave the way toward reduced heterogeneity and improved diagnosis and treatment of psychiatric disorders

Genomic Relationships, Novel Loci, and Pleiotropic Mechanisms across Eight Psychiatric Disorders

Genetic influences on psychiatric disorders transcend diagnostic boundaries, suggesting substantial pleiotropy of contributing loci. However, the nature and mechanisms of these pleiotropic effects remain unclear. We performed analyses of 232,964 cases and 494,162 controls from genome-wide studies of anorexia nervosa, attention-deficit/hyper-activity disorder, autism spectrum disorder, bipolar disorder, major depression, obsessive-compulsive disorder, schizophrenia, and Tourette syndrome. Genetic correlation analyses revealed a meaningful structure within the eight disorders, identifying three groups of inter-related disorders. Meta-analysis across these eight disorders detected 109 loci associated with at least two psychiatric disorders, including 23 loci with pleiotropic effects on four or more disorders and 11 loci with antagonistic effects on multiple disorders. The pleiotropic loci are located within genes that show heightened expression in the brain throughout the lifespan, beginning prenatally in the second trimester, and play prominent roles in neurodevelopmental processes. These findings have important implications for psychiatric nosology, drug development, and risk prediction.Peer reviewe