Hubble Space Telescope Crew Rescue Analysis

In the aftermath of the 2003 Columbia accident, NASA removed the Hubble Space Telescope (HST) Servicing Mission 4 (SM4) from the Space Shuttle manifest. Reasons cited included concerns that the risk of flying the mission would be too high. The HST SM4 was subsequently reinstated and flown as Space Transportation System (STS)-125 because of improvements in the ascent debris environment, the development of techniques for astronauts to perform on orbit repairs to damaged thermal protection, and the development of a strategy to provide a viable crew rescue capability. However, leading up to the launch of STS-125, the viability of the HST crew rescue capability was a recurring topic. For STS-125, there was a limited amount of time available to perform a crew rescue due to limited consumables (power, oxygen, etc.) available on the Orbiter. The success of crew rescue depended upon several factors, including when a problem was identified; when and what actions, such as powering down, were begun to conserve consumables; and where the Launch on Need (LON) vehicle was in its ground processing cycle. Crew rescue success also needed to be weighed against preserving the Orbiter s ability to have a landing option in case there was a problem with the LON vehicle. This paper focuses on quantifying the HST mission loss of crew rescue capability using Shuttle historical data and various power down strategies. Results from this effort supported NASA s decision to proceed with STS-125, which was successfully completed on May 24th 2009

A Real-Time Ultrasonic Imaging System (ARIS) for Manual Inspection of Aircraft Composite Structures

Inspection of aircraft composite structures at field site facilities (air bases) is routinely performed using manual ultrasonic testing (UT) techniques. Using these techniques, the examiner detects and sizes defects such as disbonds and delaminations by monitoring and interpreting A-scan waveform signals on a UT instrument display screen. Manual probe manipula- tion permits maximum scanning flexibility and optimization of the ultrasonic signal response by the examiner using manual motions not possible with mechanized scanners. However, the examiner also must be responsible for instrument calibration, signal interpretation, documentation of inspection results, and completeness of coverage. The data reviewer must be able to validate instrument calibration and completeness of coverage, confirm signal interpretation, and compare current UT results to those obtained during previous inspections

Studies on the Weak Itinerant Ferromagnet SrRuO3 under High Pressure to 34 GPa

The dependence of the Curie temperature Tc on nearly hydrostatic pressure has been determined to 17.2 GPa for the weak itinerant ferromagnetic SrRuO3 in both polycrystalline and single-crystalline form. Tc is found to decrease under pressure from 162 K to 42.7 K at 17.2 GPa in nearly linear fashion at the rate dTc/dP = -6.8 K/GPa. No superconductivity was found above 4 K in the pressure range 17 to 34 GPa. Room-temperature X-ray diffraction studies to 25.3 GPa reveal no structural phase transition but indicate that the average Ru-O-Ru bond angle passes through a minimum near 15 GPa. The bulk modulus and its pressure derivative were determined to be B =192(3) GPa and B' = 5.0(3), respectively. Parallel ac susceptibility studies on polycrystalline CaRuO3 at 6 and 8 GPa pressure found no evidence for either ferromagnetism or superconductivity above 4 K

Alternative route to charge density wave formation in multiband systems

Charge and spin density waves, periodic modulations of the electron and magnetization densities, respectively, are among the most abundant and non-trivial low-temperature ordered phases in condensed matter. The ordering direction is widely believed to result from the Fermi surface topology. However, several recent studies indicate that this common view needs to be supplemented. Here, we show how an enhanced electron-lattice interaction can contribute to or even determine the selection of the ordering vector in the model charge density wave system ErTe3. Our joint experimental and theoretical study allows us to establish a relation between the selection rules of the electronic light scattering spectra and the enhanced electron-phonon coupling in the vicinity of band degeneracy points. This alternative proposal for charge density wave formation may be of general relevance for driving phase transitions into other broken-symmetry ground states, particularly in multiband systems such as the iron based superconductors

A Highly Interactive System for Processing Large Volumes of Ultrasonic Testing Data

Automated ultrasonic testing (UT) of big structures poses particular problems related directly to economics and productivity. Generally, UT examinations on these large structures are performed with multiple channels to reduce scan time and collect data from various orientations. The amount of resulting data also is quite large. Traditional approaches have relied on up-front gating and signal thresholding to reduce the amount of data recorded. This has been a practical approach, as the capability of data processing and recording devices has also been limited. Even with the incorporation of computer technology, most systems performing UT of large structures still operate on this same data acquisition principle. General purpose computer configurations lack the performance to provide any substantial improvement in data analysis. Computer resources have been focused on number crunching, data summary, and data comparison using general criteria such as signal amplitude and sound path location. In practice, examiners use this type of system to identify areas of concern and then perform “re-looks” while observing the instrument A-scan display. Years of experience are then applied in interactive analysis of the A-scans for final resolution. For the particular area of concern, as much additional information as possible is collected (e.g., different angles and orientations) to provide information crucial to the final disposition. If the system collected the proper data and was capable of presenting these data in a meaningful format, this manual “re-look” procedure would not be necessary

Factors Influencing Graduate Program Choice Among Undergraduate Women

Context: Despite equal enrollment proportions in MD and PhD programs, there are fewer women than men in MD-PhD programs and academic medicine. Factors important in degree program selection, including the perception of gender disparities, among undergraduate students were characterized. Methods: In 2017, pre-health students at four public North Carolina universities were invited to participate in an online survey regarding career plans, decision factors, and perceptions of gender disparities in MD, PhD and MD-PhD pathways. The authors characterized factors important to program selection, and evaluated the association of intended graduate program with perceived gender disparities using Fisher’s exact tests. Results: Among the n=186 female survey participants, most were white (54%) and intended MD, PhD, and/or MD-PhD programs (52%). Sixty percent had heard of MD-PhD programs, over half had no research experience, and half were considering but uncertain about pursuing a research career. The most common factors influencing degree program choice were perceived competitiveness as an applicant, desired future work environment, and desire for patient interaction. Twenty-five percent of students considering MD, PhD, and MD-PhD programs stated that perceived gender disparities during training for those degrees will influence their choice of program, however intended degree was not statistically associated with perceived gender disparities. Discussion: Perceived gender disparities may influence choice of graduate training program but are not among the top factors. Perceived competitiveness as an applicant is an important career consideration among undergraduate women. Strategies to increase awareness of MD-PhD programs, to encourage women to consider all training paths for which they are qualified are needed. Keywords: Education, Graduate; Sexism; Career Choice; Biomedical Research/education; Female What is known: Though men and women are nearly equally represented in MD-only and PhD-only programs, women are underrepresented in MD-PhD programs, which train physician-scientists. Prior studies have shown gender is not associated with rates of attrition from MD-PhD programs or differences in academic preparation, research interest, or research experience, suggesting enrollment differences by gender may be due to fewer women applying to MD-PhD programs. Gender parity in the physician-scientist workforce is critical to equitably serving a diverse patient population. What this study adds: This study is the first to examine the role of gender disparities in the career choices of undergraduate women. Given the moderate familiarity with MD-PhD training and lack of research experience among respondents, increased awareness of MD-PhD programs and expanded research opportunities may help undergraduates make informed career choices. This may increase women MD-PhD applicants, creating a more balanced physician-scientist workforce to address the needs of patients from all backgrounds