Low cost attitude control system scanwheel development

In order to satisfy a growing demand for low cost attitude control systems for small spacecraft, development of low cost scanning horizon sensor coupled to a low cost/low power consumption Reaction Wheel Assembly was initiated. This report addresses the details of the versatile design resulting from this effort. Tradeoff analyses for each of the major components are included, as well as test data from an engineering prototype of the hardware

Modular Attitude Determination and Control System for Small Satellites

In order to meet the cost goals of small satellites, attitude determination and control problems must be solved using standardized components. Small satellite attitude control systems must feature performance, versatility, and above all, low cost Large, custom designed, high cost attitude control systems have no place in the small satellite community. A modular concept of attitude control is presented which will allow ambitious performance and cost goals to be attained. Basic building blocks allow mission specific goals to be reached with a minimum of effort and expense. Several basic modules are described and applied to a number of representative mission requirements. The concept illustrates a philosophy of modularity, flexibility, and manufacturability so necessary to the small satellite community

Magnetic Attitude Control System for Spinning Small Spacecraft

A magnetic Attitude Control Subsystem (ACS) designed for minimum power weight, and cost is presented. The ACS subsystem was designed and built by ITHACO for the Small Communications Satellite Cluster (SCSC), integrated by Defense Systems Incorporated for the Defense Advanced Research Projects Agency. The basic spacecraft configuration is a flat cylinder, having a mass of 22.7 Kg with a diameter of 47.2 cm and 17.0 cm height. Hardware for the ACS design includes a two-axis magnetometer, two TORQRODs, a Horizon Crossing Indicator and the host microprocessor. During acquisition mode, the ACS spins up and stabilizes the spacecraft with a spin rate of 3 RPM (within 10%) and the spin-axis to within 5° of the orbit normal. Simulation results show that the above objectives can be achieved with the 1 Am2 TORQRODs within 4 orbits with total ACS orbital average power consumption of 190 mW and total ACS mass of 0.428 Kg

Effects of Anacetrapib in Patients with Atherosclerotic Vascular Disease

BACKGROUND: Patients with atherosclerotic vascular disease remain at high risk for cardiovascular events despite effective statin-based treatment of low-density lipoprotein (LDL) cholesterol levels. The inhibition of cholesteryl ester transfer protein (CETP) by anacetrapib reduces LDL cholesterol levels and increases high-density lipoprotein (HDL) cholesterol levels. However, trials of other CETP inhibitors have shown neutral or adverse effects on cardiovascular outcomes. METHODS: We conducted a randomized, double-blind, placebo-controlled trial involving 30,449 adults with atherosclerotic vascular disease who were receiving intensive atorvastatin therapy and who had a mean LDL cholesterol level of 61 mg per deciliter (1.58 mmol per liter), a mean non-HDL cholesterol level of 92 mg per deciliter (2.38 mmol per liter), and a mean HDL cholesterol level of 40 mg per deciliter (1.03 mmol per liter). The patients were assigned to receive either 100 mg of anacetrapib once daily (15,225 patients) or matching placebo (15,224 patients). The primary outcome was the first major coronary event, a composite of coronary death, myocardial infarction, or coronary revascularization. RESULTS: During the median follow-up period of 4.1 years, the primary outcome occurred in significantly fewer patients in the anacetrapib group than in the placebo group (1640 of 15,225 patients [10.8%] vs. 1803 of 15,224 patients [11.8%]; rate ratio, 0.91; 95% confidence interval, 0.85 to 0.97; P=0.004). The relative difference in risk was similar across multiple prespecified subgroups. At the trial midpoint, the mean level of HDL cholesterol was higher by 43 mg per deciliter (1.12 mmol per liter) in the anacetrapib group than in the placebo group (a relative difference of 104%), and the mean level of non-HDL cholesterol was lower by 17 mg per deciliter (0.44 mmol per liter), a relative difference of -18%. There were no significant between-group differences in the risk of death, cancer, or other serious adverse events. CONCLUSIONS: Among patients with atherosclerotic vascular disease who were receiving intensive statin therapy, the use of anacetrapib resulted in a lower incidence of major coronary events than the use of placebo. (Funded by Merck and others; Current Controlled Trials number, ISRCTN48678192 ; ClinicalTrials.gov number, NCT01252953 ; and EudraCT number, 2010-023467-18 .)

Associations between self-harm and distinct types of impulsivity

Objective There is an ongoing debate regarding how self-harm should be classified. The aim of this study was to characterize associations between self-harm and impulsivity. Method Total 333 adults (mean [SD] age 22.6 (3.6) years, 61% male) were recruited from the general community. History of self-harm was quantified using the Self-Harm Inventory (SHI), which asks about 22 self-harm behaviors. Principal components analysis was used to identify latent dimensions of self-harming behaviors. Relationships between self-harm dimensions and other measures were characterized using ordinary least squares regression. Results Principal Components Analysis yielded a three factor solution, corresponding to self-injurious self-harm (e.g. cutting, overdoses, burning), interpersonal related self-harm (e.g. engaging in emotionally or sexually abusive relationships), and reckless self-harm (e.g. losing one's job deliberately, driving recklessly, abusing alcohol). Regression modelling showed that all three dimensions of self-harm were associated with lower quality of life. Conclusions This study suggests the existence of three distinct subtypes or ‘latent factors’ of self-harm: all three appear clinically important in that they are linked with worse quality of life. Clinicians should screen for impulse control disorders in people with self-harm, especially when it is self-injurious or involves interpersonal harm.</p