AX-5 space suit bearing torque investigation

The symptoms and eventual resolution of a torque increase problem occurring with ball bearings in the joints of the AX-5 space suit are described. Starting torques that rose 5 to 10 times initial levels were observed in crew evaluation tests of the suit in a zero-g water tank. This bearing problem was identified as a blocking torque anomaly, observed previously in oscillatory gimbal bearings. A large matrix of lubricants, ball separator designs and materials were evaluated. None of these combinations showed sufficient tolerance to lubricant washout when repeatedly cycled in water. The problem was resolved by retrofitting a pressure compensated, water exclusion seal to the outboard side of the bearing cavity. The symptoms and possible remedies to blocking are discussed

Monetary policy without reserve requirements : case studies and options for the United States

Over the past decade, the level of required balances held by depository institutions in the United States has declined dramatically. The decline in reserve balances has fueled a debate over the role of reserve requirements. On the one hand, proponents of reserve requirements argue that low reserve balances may complicate monetary policy operations and increase short-term interest rate volatility. On the other hand, critics of reserve requirements argue that lower reserve requirements remove a distortionary tax on depository institutions and need not complicate monetary policy operations. ; In this article, the authors examine how three countries - Canada, the United Kingdom, and New Zealand conduct monetary policy without using reserve requirements. The experience of these three countries provides insight into the linkages between the payments system and monetary policy and into the connection between reserve requirements and interest rate volatility. This insight is particularly helpful in understanding the implications of a further reduction of reserve balances in the United States.Monetary policy ; Bank reserves ; Monetary policy - Canada ; Monetary policy - Great Britain ; Monetary policy - New Zealand

The Alternative to Laparoendoscopic Single-Site Surgery: Small Strategic Laparoscopic Incision Placement (SLIP) Nephrectomy Improves Cosmesis Without Technical Restrictions

Background: The latest attempt to improve the cosmesis of laparoscopic surgery is laparoendoscopic single-site surgery (LESS). We present our initial experience with an alternative procedure with similar cosmetic benefit but without technical limitations. Methods: Small strategic laparoscopic incision placement (SLIP) nephrectomy is performed transperitoneally, generally using three 5-mm ports (one in the umbilicus) and one 12-mm port placed below the pubic hairline, such that only two 5-mm scars are visible without close inspection. We assessed our first 21 procedures, which included all but five of the standard transperitoneal nephrectomies by a single surgeon from June 2008 through July 2009. These were matched 1:2 (exactly by gender and American Society of Anesthesiology score, and then closest in age and body mass index) from 96 patients undergoing similar standard transperitoneal laparoscopic procedures from 2005 through 2008. Results: The SLIP and control groups were well matched, with mean age and body mass index differing by only 3.6 years and 1.1, respectively. Of the SLIP patients, 34% were obese or morbidly obese, and a trainee was the primary surgeon in 81% of cases. Mean operative time was 23 minutes longer in the SLIP cases. There was no difference between groups in estimated blood loss, complication rate, or convalescence. Conclusions: Like LESS, SLIP nephrectomy provides improved cosmesis. Unlike LESS, it is only slightly more difficult to perform than standard laparoscopic nephrectomy and can be performed in technically challenging cases (obesity, large specimen, etc). Similar to the literature on LESS, there is no convalescence benefit to SLIP nephrectomy; the advantage over standard laparoscopy is purely cosmetic.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90438/1/end-2E2010-2E0340.pd

Laparoscopic Transperitoneal Pyeloplasty

Laparoscopic pyeloplasty is a first-line option for the management of ureteropelvic junction obstruction. It has a greater success rate than endopyelotomy and is associated with a shorter and less intense convalescence than open surgical pyeloplasty. The technique is well established and reproducible, although the procedure is more difficult in certain situations, such as after a previous pyeloplasty. Because laparoscopic suturing is needed, it is considered an advanced laparoscopic procedure. Suturing devices can facilitate suturing, but they are not optimal for all repairs. This article and the accompanying video summarize the preoperative, intraoperative, and postoperative considerations for laparoscopic pyeloplasty.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90443/1/end-2E2010-2E0605.pd

Power technologies and the space future

Advancements in space power and energy technologies are critical to serve space development needs and help solve problems on Earth. The availability of low cost power and energy in space will be the hallmark of this advance. Space power will undergo a dramatic change for future space missions. The power systems which have served the U.S. space program so well in the past will not suffice for the missions of the future. This is especially true if the space commercialization is to become a reality. New technologies, and new and different space power architectures and topologies will replace the lower power, low-voltage systems of the past. Efficiencies will be markedly improved, specific powers will be greatly increased, and system lifetimes will be markedly extended. Space power technology is discussed - its past, its current status, and predictions about where it will go in the future. A key problem for power and energy is its cost of affordability. Power must be affordable or it will not serve future needs adequately. This aspect is also specifically addressed

Failure After Laparoscopic Pyeloplasty: Prevention and Management

Background and Purpose: Because of the high success of laparoscopic pyeloplasty (LP) for ureteropelvic junction obstruction, strategies for managing failures are less well described. We report our experience with persistent or recurrent obstruction after LP. Patients and Methods: We reviewed 128 patients who were treated with LP at our institution from 1996 through 2008. Success was defined as objective resolution of obstruction by renal scintigraphy, Whitaker testing, or direct visualization. We extracted data by chart review regarding patient demographics, medical history, operative technique, and salvage treatments. We then assessed for association between patient characteristics and treatment failure. Results: Overall, 102 patients had sufficient follow-up, of which 84 (82%) were successes. Of 18 failures, median time to failure was 2.5 months (0.5-88-mos). Of 10 failures managed endoscopically, 7 were salvaged. One of two patients treated conservatively ultimately had resolution while six patients needed simple nephrectomy. Overall, 8 (44%) were salvageable with median follow-up of 19 months (4-58-mos). Patients with failure were more likely to have diabetes mellitus, longer length of stay, higher American Society of Anesthesiologists (ASA) score, a stent placed at the time of pyeloplasty, or ureteral stent malfunction (P30-kg/m2 (P2 were associated with failure (P<0.05) while periureteral fibrosis trended toward a significant association (P=0.061). Conclusion: Nearly half of failures after LP are salvageable, many with endoscopic management.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90445/1/end-2E2010-2E0647.pd

Ex-Vivo Ureteroscopy at the Time of Live Donor Nephrectomy

Background and Purpose: Potential transplant renal allograft recipients exceed the number of donors. Our institution now considers patients with small, unilateral, nonobstructing, incidental renal calculi for possible renal donation. We adopted ex-vivo ureteroscopy (ExURS) to render these kidneys stone free at the time of renal transplantation. We examined the safety and efficacy of ExURS. Patients and Methods: After confirming a lack of significant metabolic defects on 24-hour urinalysis, 23 patients with small nonobstructing unilateral nephrolithiasis detected on preoperative CT angiography underwent donor nephrectomy. Immediately after cold perfusion, ExURS was performed with ice cold saline irrigation. Retrospective review was performed. Results: Pyeloscopy was successfully performed in all 23 patients. A total of 28 calculi, mean largest diameter 3.9-mm (range 3-6-mm), were visualized in 19 kidneys. Basket extraction and holmium laser lithotripsy was performed in 12 and 6 kidneys, respectively. Treatment rendered 17/19 stone-containing kidneys stone free with a mean treatment time of 6.2 minutes (3-10-min). There were no intraoperative complications. Median serum creatinine level of recipients at 1 month and 1 year were 1.4+/-1.8-mg/dL and 1.3+/-0.6-mg/dL, respectively. At a median follow-up of 63+/-47.2 months, there were no transplant urinary calculi among the recipients. Conclusions: ExURS safely renders live donor kidney allografts stone free with low risk of recurrence. When used appropriately, ExURS could safely increase the number of potential kidney donors and minimize the risk of adverse stone events.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90444/1/end-2E2010-2E0627.pd