β Lyrae: on the magnetic field

β Lyrae shows a complicated and intricate time-dependent behaviour of the magnetic field

The Phoenix Mars Landing: An Initial Look

This presentation was part of the session : Ongoing and Proposed EDL Technology DevelopmentSixth International Planetary Probe WorkshopNASA's Phoenix Mars Lander will make a landing on Mars on May 25th, 2008. Following on from the overview of the Phoenix entry, descent and landing (EDL) system given at IPPW5, an initial look at the Phoenix landing will be presented, highlighting the salient, high level events that occurred during EDL. Initial EDL flight reconstruction results will be presented, along with a retelling of the flight operations events that occurred on approach to Mars, and during the landing event itself. Note: Given the short time duration between the Phoenix landing and IPPW6, only a presentation will be prepared for the workshop.NAS

Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Assessment of Mars Phoenix EDL Performance

Entry, Descent, and Landing (EDL) is an especially risky phase of a planetary mission, and detailed information on the performance of a lander's EDL design is critical to mitigating the risks of future missions. 12However, the study of actual EDL performance and comparison with the pre-entry predictions has not typically been given a high priority following spacecraft landings, mainly for budgetary reasons. Because Mars Phoenix inherited hardware and design elements from a similar mission that appears to have failed during Mars EDL, NASA was particularly interested in identifying the reasons for the Phoenix mission success. Therefore, NASA sponsored a reconstruction and analysis of the downlinked Phoenix telemetry that would tell the story of this critical event sequence--focusing on the 14 minutes from cruise stage separation to landing--and identify lessons learned

Peuton, Sippur Be-Haruzim

Peuton [lit: Tiny] A Tale in Rhymes. Author: S[hlomo] Skulsky. Illustrator: Zvi Livni. Publisher: Daat Publishing. ; 23 pp, 11 color full-page ills. + color cover ill. [goats; Elijah; animals]Digital imagedigitize

The magnetic field of the

The presence of a magnetic field in β Lyrae was firstly suggested by Babcock in 1958 and then confirmed by Skulsky in 1982. This kG-order large-scale organized magnetic field has been neglected in interpreting and modeling the large variety of phenomena presented by β Lyrae. Here, we present circular spectropolarimetry of β Lyrae showing that its magnetic field is variable with the orbital period and that it has changed in sign and strength between 1980 and 2000. Unfortunately, there are not enough data to conclude if a longer-time variability is super-imposed on the orbital period variability or if the field changes abruptly. This magnetic field, to our knowledge, is unique. Since we measured the magnetic field in metal lines of the brightest star of the system, we can conclude that this is the first magnetic B-type giant star. In this case, the magnetic field is significantly different from that of Magnetic Chemically Peculiar stars and the long-time-scale variability suggests the presence of a dynamo. However, we cannot rule out that the magnetic field measured on the brightest star is generated by the accretion disk, or that the magnetic field of the embedded star is so elongated in the orbital plane by the disk that it still has a significant strength even at the companion distance. In any case, the accretion disk is certainly related to the magnetic field of the β Lyrae system. We found that variations of the field in sign and strength corresponded to variations in the disk structure, as it is inferred from photometry and spectroscopy. Also, a magnetized disk explains the observed jet-like outflow from the β Lyrae system

Measuring recent thymic emigrants in blood of normal and HIV-1-infected individuals before and after effective therapy.

The role of the thymus in HIV-1 pathogenesis remains unclear. We developed an assay to quantify the number of recent thymic emigrants in blood based on the detection of a major excisional DNA byproduct (termed alpha1 circle) of T cell receptor rearrangement. By studying 532 normal individuals, we found that alpha1 circle numbers in blood remain high for the first 10-15 yr of life, a sharp drop is seen in the late teen years, and a gradual decline occurs thereafter. Compared with age-matched uninfected control individuals, alpha1 circle numbers in HIV-1-infected adults were significantly reduced; however, there were many individuals with normal alpha1 circle numbers. In 74 individuals receiving highly active antiretroviral therapy, we found no appreciable effect on alpha1 circle numbers in those whose baseline values were already within the normal range, but significant increases were observed in those with a preexisting impairment. The increases in alpha1 circle numbers were, however, numerically insufficient to account for the rise in levels of naive T lymphocytes. Overall, it is difficult to invoke thymic regenerative failure as a generalized mechanism for CD4 lymphocyte depletion in HIV-1 infection, as alpha1 circle numbers are normal in a substantial subset of HIV-1-infected individuals