Reach performance while wearing the Space Shuttle launch and entry suit during exposure to launch accelerations

Crewmen aboard the Space Shuttle are subjected to accelerations during ascent (the powered flight phase of launch) which range up to +3 G(sub x). Despite having 33 missions and nine years experience, not to mention all the time spent in development prior to the first flight, no truly quantitative reach study wearing actual crew equipment, using actual Shuttle seats and restraints has ever been done. What little information exists on reach performance while under acceleration has been derived primarily from subjective comments gathered retrospectively from Shuttle flight crews during their post mission debrief. This lack of reach performance data has resulted in uncertainty regarding emergency procedures that can realistically be performed during and actual Shuttle ascent versus what is practiced in the ground-fixed and motion-based Shuttle Simulators. With the introduction on STS-26 of the current Shuttle escape system, the question of reach performance under launch accelerations was once again raised. The escape system's requirement that each crewman wear a Launch/Entry Suit (LES), parachute harness, and parachute were all anticipated to contribute to a further degradation of reach performance during Shuttle ascent accelerations. In order to answer the reach performance question in a quantitative way, a photogrammetric method was chosen so that the actual reach values and associated envelopes could be captured. This would allow quantitative assessment of potential task performance impact and identify areas where changes to our Shuttle ascent emergency procedures might be required. Also, such a set of reach values would be valid for any similar acceleration profile using the same crew equipment. Potential Space Station applications of this data include predicting reach performance during Assured Crew Return Vehicle (ACRV) operations

Software-Enabled Smallsat Autonomy: Discussion with Examples

Smallsat missions using cooperating constellations offer significant benefits compared to traditional space missions. These benefits include lower unit costs, better robustness to failures, and the ability to collect data in a distributed fashion. Significant commercial smallsat missions are active in low Earth orbit, and spacecraft operators have expressed interest in smallsat constellations operating both at higher altitudes and in proximity operations missions. Autonomy plays a significant role in extending smallsat missions to these more challenging domains. Autonomy in a broad sense refers to a spacecraft\u27s or constellation\u27s ability to operate independently of ground systems, and affects every part of a typical mission. For example, onboard processing of data can significantly reduce the frequency and expense of communications to a terrestrial ground station link. Onboard safety and health management is critical in proximity operations with fast dynamics, or in remote operations where offboard monitoring is available infrequently. Onboard monitoring of mission objectives enables remote operations and reduces the required operator workload. Emergent Space Technologies has developed flight software products to enable future missions with greater autonomy. Navigator is a standalone application for cooperative absolute and relative navigation within a cluster of space vehicles. The Autopilot software suite enables routine orbit maintenance and satellite maneuvers to be monitored and executed onboard, increasing safety and reducing reliance on ground systems. Guardian is a suite of applications thatenable fault detection, isolation, and recovery on modules within a distributed mission. The Cirrus cloud computing framework enables distributed computing tasks within a fleet of cooperating platforms, allowing complex data processing algorithms to be executed onboard and distributed among vehicles according to their computational availability. Finally, Commander is a set of applications for autonomous execution of a planned mission on a distributed group of platforms. Critically, Commander enables autonomous coordination of the actions of Navigator, Autopilot, Guardian, and Cirrus, providing a significantly greater level of autonomy than the suites provide individually. In this paper, we describe the capabilities of the flight software and demonstrate how coordination using Commander enables desired operator missions. The following missions are considered: (1) autonomous lunar injection; (2) rendezvous and proximity operations; (3) constellation intelligence, surveillance, and reconnaissance. Discussion is informed by use case diagrams and simulation results using Emergent\u27s Ascent simulation environment

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Daily variation in post traumatic stress symptoms in individuals with and without probable post traumatic stress disorder

Abstract Background Little is known about the extent to which post traumatic stress symptoms (PTSS) vary from day to day in individuals with post traumatic stress disorder (PTSD). This study examined the variation of PTSS by day of the week, and whether daily or day of week variation differs between individuals with and without probable PTSD. Methods Subjects (N = 80) were assessed for probable PTSD at enrollment. Using an ecological momentary assessment methodology, PTSS were assessed four times daily by self-report for 15 days. Linear mixed models were used to assess the relationship of PTSS and day of the week. Results PTSS varied across the seven days of the week among participants with PTSD (p = .007) but not among those without PTSD (p = .559). Among those with PTSD, PTSS were lowest on Saturday. PTSS were higher on weekdays (Monday through Friday) versus weekends (Saturday and Sunday) in those with PTSD (p = .001) but there were no weekday/weekend differences among those without PTSD (p = .144). These variations were not explained by sleep medication, caffeine or alcohol use. Conclusions Among individuals with probable PTSD, post traumatic stress symptoms vary by the day of the week, with more symptoms on weekdays compared to weekends. Determination of the factors associated with the daily variation in PTSD symptoms may be important for further developing treatments for PTSD

POVERTY IN RURAL INDIA: CASTE AND TRIBE

This paper analyzes the determinants of rural poverty in India, contrasting the situation of scheduled caste (SC) and scheduled tribe (ST) households with the non-scheduled population. The incidence of poverty in SC and ST households is much higher than among non-scheduled households. By combining regression estimates for the ratio of per capita expenditure to the poverty line and an Oaxaca-type decomposition analysis, we study how these differences in the incidence of poverty arise. We find that for SC households, differences in characteristics explain the gaps in poverty incidence more than differences in transformed regression coefficients. In contrast, for ST households, differences in the transformed regression coefficients play the more important role. Copyright 2008 The Authors.