Hybrid Rocket Engine Ignition and Control

Control of a hybrid rocket engine is dependent upon a robust system capable of executing commands at precise times. In order to accomplish this, hardware systems must be in place to control the flow of a pressurized gas and provide feedback to launch site personnel. Through the use of solenoid valves and wireless transceivers, control over the thrust of a rocket can be accomplished. In order to understand this information and provide a user-friendly interface to complete this, a launch control module is used. Through the combined capabilities of the two system it becomes possible to test and launch a hybrid engine rocket in a safe and efficient manner

A Note on the Implementation of Hierarchical Dirichlet Processes

The implementation of collapsed Gibbs samplers for non-parametric Bayesian models is non-trivial, requiring considerable book-keeping. Goldwater et al. (2006a) presented an approximation which significantly reduces the storage and computation overhead, but we show here that their formulation was incorrect and, even after correction, is grossly inaccurate. We present an alternative formulation which is exact and can be computed easily. However this approach does not work for hierarchical models, for which case we present an efficient data structure which has a better space complexity than the naive approach.4 page(s

Studies on some responses of Carcinus maenas (L.) and other brachyurans to hypoxia and aerial exposure

This work comprises a series of investigations of the effects of changes in environmental oxygen levels, which occur with hypoxia or aerial exposure, on the osmo-regulatory capacity, acid-base balance and general respiratory physiology of brachyuran crabs. The principal species studied was Carcinus maenas, although Cancer pagurus and Liocarcinus puber were also included in the aerial exposure experiments.The effects of exposure to 4hr of moderate (Pw02 = 40 torr) or severe (Pw02 = 20 torr) hypoxia at 15°C on various blood solutes, acid-base balance and general respiratory physiology were assessed for C.maenas in low salinity (10.0, 13.5 and 19.0%.S) and fully marine (30.0%.S) media. Haemolymph pH increased at all test salinities and to an extent which was salinity/Pw02 dependent. During hypoxia the heart rate (fh) was not significantly affected at any salinity but the scaphognathite rate (fsc ) increased significantly (P0.05) increases in haemocyanin and total blood protein levels were recorded at both salinities (cf. normoxic animals). In starved groups at both salinities blood protein levels were maintained under hypoxia but control animals showed a fall in protein levels.The responses of the crabs C.maenas, C.pagurus and L.puber to short (4hr) and longer (24hr) term aerial exposure were investigated. On exposure to air oxygen consumption (M02) was reduced significantly (P<0.05) in C.pagurus and L.puber (cf. aquatic respiration rates), but the M02 of C.maenas in air was comparable to that in water. No marked change in fH or f sc were recorded in C.maenas during re-immersion following aerial exposure but in L.puber tachycardia and hyperventilation were observed. In air (4hr) there were no changes to blood lactate levels in C.maenas but pronounced changes were found in C.pagurus and L.puber. Long-term aerial exposure resulted in mortalities and significant (P<O.OS) increases in blood glucose and lactate levels in C.pagurus and L.puber but no mortalities or marked changes to these metabolites in C.maenas. The findings have been considered in relation to the structure and resistance to collapse of the gill lamellae in air

Patient No-show for Outpatient Physical Therapy: A National Survey

Introduction: Patients who fail to show for scheduled medical appointments (no-show) create a cascade of issues for the health care system, the provider, and themselves. No-show can affect clinical productivity, cost and quality of care, and treatment outcomes. There is an overwhelming lack of research on no-show as it relates to outpatient physical therapy in the United States. The purposes of this study were to report national no-show rates, describe the presence and characteristics of no-show policies, determine the relationship of these policies and other demographic information to no-show rates, and describe the most commonly perceived reasons for no-show. Methods: An online survey was developed and made available to an estimated 7,128 outpatient physical therapists currently practicing in the United States. Participants received the survey link through one of four methods: in person at the 2014 American Physical Therapy Association (APTA) Combined Sections Meeting, through direct mail to APTA members registered as outpatient practitioners, through social media postings, and through an online newsletter available to members of the International Spine and Pain Institute. The survey requested information regarding demographics, clinical setting, reasons for no-show, no-show rates, and no-show policies. T-tests, one-way ANOVAs, and Kruskal-Wallis tests were used to compare clinic no-show rates among locations, settings, and different no-show policies, and to ultimately make future no-show policy recommendations based upon significant findings. Results: Of the 802 surveys that were completed, 634 reported a no-show rate. Nationwide the mean no-show rate was 10.4% (±7.43). About half (52.5%) of respondents were from private outpatient clinics and 77.4% of respondents reported their clinic has a written no-show policy. The #1 most commonly reported reason for no-show was that the patient “forgot”. Private clinics reported significantly lower no-show rates (7.81%±5.92) than hospital-campus clinics (14.53%±8.17; p \u3c 0.001) and pediatric clinics (12.86%±9.50; p = 0.049). Employing a multi-method reminder system along with requiring a 24 hour cancellation notice was associated with a significantly lower no-show rate when compared to only using phone call reminders (multi-method and 24 hour notice = 6.07%±4.59, phone call only = 13.80%±9.66; p = 0.019). In addition, no-show consequences that included a fee were associated with a significantly lower no-show rate than those that included the possibility of discharge (“charge a fee” = 8.85%±6.13, “discharge” = 13.22%±8.67; p = 0.049). Discussion: The majority of outpatient physical therapy clinics (77.4%) have written no-show policies, and although no-show policy characteristics and the rates associated with them are diverse, it appears that a proactive policy may limit no-show frequency. No-show policies are needed and useful when considering a nationwide mean no-show rate of 10.4%, “forgot” as the #1 perceived reason for no-show, and significant findings regarding specific strategies and consequences that limit no-show. The impact of no-show on productivity, revenue, cost and quality of care, and patient outcomes are all areas for future research. Conclusions: Based on the data, the authors recommend a policy including multiple methods of reminders (emails, phone calls, and text messages) and requiring that the patient give 24-hour notice of cancellation or face a financial penalty

A Comparison Pilot Study of Motor-level Electrical Stimulations for Lowering Postprandial Glucose Levels

Abstract Purpose: The purpose of this study is to compare the effects of three Motor-level Electrical Stimulation (MES) parameters, NMES, Russian current, and low-rate transcutaneous electric nerve stimulation (TENS) on non-diabetic healthy subjects’ postprandial glucose levels, heart rate, and oxygen consumption (VO2). Background: MES has been shown to improve glucose tolerance and glucose uptake in both animals and humans. The effects of MES include increasing the following: heart rate, blood pressure, oxygen uptake, ventilatory capacity, muscle bulk, muscle oxidative process, and muscle glycogen depletion. Recently, MES has been shown to improve blood glucose control in people with type 2 diabetes. However, limited research is available that comprehensively compares varying MES parameters on the effects of postprandial glucose levels. Methods: Twenty-eight healthy student subjects were randomly assigned to either the NMES, Russian current, TENS, or control group without any MES. Subjects participated in an overnight fast of at least 8 hours and had their fasting blood glucose measured. Subjects were given a glucose supplement to drink within 10 minutes, rested in supine for 30 minutes then the second glucose level was taken. Subjects received a 30 minute treatment intervention followed by the third blood glucose measurement. Subjects then rested an additional 30 minutes followed by obtaining the final blood glucose measurement. VO2 levels were monitored every 30 seconds, and heart rate was monitored every 3 minutes throughout the 90 minute study. Results: There were no significant differences between groups on glucose levels and heart rates throughout the study. The Russian group demonstrated a statistically significant increase up to 10% in VO2 compared to the control group. Conclusion: MES seems to have no effects on postprandial glucose levels in non-diabetic healthy subjects. While 30-minute MES treatment did not change the heart rate, Russian current significantly increased the VO2. Our findings indicate Russian current may have the potential to be applied to mimic exercise better than NMES or TENS. Further research is required to explore the effects of Russian current on blood glucose levels in people with T2D

Conceptual analysis of a lunar base transportation system

Important to the planning for a lunar base is the development of transportation requirements for the establishment and maintenance of that base. This was accomplished as part of a lunar base systems assessment study conducted by the NASA Langley Research Center in conjunction with the NASA Johnson Space Center. Lunar base parameters are presented using a baseline lunar facility concept and timeline of developmental phases. Masses for habitation and scientific modules, power systems, life support systems, and thermal control systems were generated, assuming space station technology as a starting point. The masses were manifested by grouping various systems into cargo missions and interspersing manned flights consistent with construction and base maintenance timelines. A computer program that sizes the orbital transfer vehicles (OTV's), lunar landers, lunar ascenders, and the manned capsules was developed. This program consists of an interative technique to solve the rocket equation successively for each velocity correction (delta V) in a mission. The delta V values reflect integrated trajectory values and include gravity losses. As the program computed fuel masses, it matched structural masses from General Dynamics' modular space-based OTV design. Variables in the study included the operation mode (i.e., expendable vs. reusable and single-stage vs. two-stage OTV's), cryogenic specific impulse, reflecting different levels of engine technology, and aerobraking vs. all-propulsive return to Earth orbit. The use of lunar-derived oxygen was also examined for its general impact. For each combination of factors, the low-Earth orbit (LEO) stack masses and Earth-to-orbit (ETO) lift requirements are summarized by individual mission and totaled for the developmental phase. In addition to these discrete data, trends in the variation of study parameters are presented