Managing Radiation Degradation of CCDs on the Chandra X-Ray Observatory--III

The CCDs on the Chandra X-ray Observatory are vulnerable to radiation damage from low-energy protons scattered off the telescope's mirrors onto the focal plane. Following unexpected damage incurred early in the mission, the Chandra team developed, implemented, and maintains a radiation-protection program. This program--involving scheduled radiation safing during radiation-belt passes, intervention based upon real-time space-weather conditions and radiation-environment modeling, and on-board radiation monitoring with autonomous radiation safing--has successfully managed the radiation damage to the CCDs. Since implementing the program, the charge-transfer inefficiency (CTI) has increased at an average annual rate of only 3.2x 10(exp -6) (2.3 percent) for the front-illuminated CCDs and 1.0x10(exp -6) (6.7 percent) for the back-illuminated CCDs. This paper describes the current status of the Chandra radiation-management program, emphasizing enhancements implemented since the previous papers

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

The impact of immediate breast reconstruction on the time to delivery of adjuvant therapy: the iBRA-2 study

Background: Immediate breast reconstruction (IBR) is routinely offered to improve quality-of-life for women requiring mastectomy, but there are concerns that more complex surgery may delay adjuvant oncological treatments and compromise long-term outcomes. High-quality evidence is lacking. The iBRA-2 study aimed to investigate the impact of IBR on time to adjuvant therapy. Methods: Consecutive women undergoing mastectomy ± IBR for breast cancer July–December, 2016 were included. Patient demographics, operative, oncological and complication data were collected. Time from last definitive cancer surgery to first adjuvant treatment for patients undergoing mastectomy ± IBR were compared and risk factors associated with delays explored. Results: A total of 2540 patients were recruited from 76 centres; 1008 (39.7%) underwent IBR (implant-only [n = 675, 26.6%]; pedicled flaps [n = 105,4.1%] and free-flaps [n = 228, 8.9%]). Complications requiring re-admission or re-operation were significantly more common in patients undergoing IBR than those receiving mastectomy. Adjuvant chemotherapy or radiotherapy was required by 1235 (48.6%) patients. No clinically significant differences were seen in time to adjuvant therapy between patient groups but major complications irrespective of surgery received were significantly associated with treatment delays. Conclusions: IBR does not result in clinically significant delays to adjuvant therapy, but post-operative complications are associated with treatment delays. Strategies to minimise complications, including careful patient selection, are required to improve outcomes for patients

A Multi-Role Architecture Using Turbine Based Combined Cycle

2004 RASC-Al Design Competition Fort Lauderdale, FL, July 11 - 14, 2004.In the fall of 2003 a multi-disciplinary team consisting of graduate students from the Space Systems Design Lab (SSDL), the Aerospace Systems Design Lab (ASDL), and the Elevated Temperature Structural Durability Lab (ETSDL) was assembled at Georgia Tech. This project marked the first joint venture between these labs and brought together a diverse wealth of tools, knowledge, and experience, as well as a group of individuals with keen interest in the future of access-to-space vehicles. The Knight RIDER revolutionary aerospace systems concept was formulated in response to a mock Request for Proposal (RFP) inviting architectural designs to enable six specific Design Reference Missions (DRMs) with a small set of common vehicles and components. Effects of this architecture-level approach were anticipated to be improved reliability and significantly increased economic viability due to cost sharing between multiple customers. The RFP specified horizontal take-off and landing capability, the use of Turbine Based Combined Cycle (TBCC) propulsion, and an operational timeframe of 2015-2030. The six DRMâ s can be summarized as follows: DRM1: Civil Cargo to Low Earth Orbit(LEO), Customer: NASA, Requirement: 20,000lb payload DRM2: International Space Station Crew Rotation, Customer: NASA, Requirement: 2 pilots, 4 crew DRM3: Long Range Strike Aircraft, Customer: USAF, Requirement: 8900 nmi range, 2-hour strike DRM4: Cargo to Geosynchronous Transfer Orbit(GTO), Customer: Commercial, Requirement: 10,000lb DRM5: High-Speed Global Transport, Customer: Commercial, Requirement: 6500 nmi range, 100 pax DRM6: Space Tourism Vehicle, Customer: Commercial, Requirement: 2 pilots, 6-16 passengers Each DRM had the basic performance requirements listed above as well as more detailed requirements such as target reliabilities, g-load limitations, flight rates, and conformance to various government regulations. Each DRM was also coupled with specific economic requirements outlining limitations on initial investment costs, recurring costs per flight, and required return on investment