High efficiency SPS klystron design

The most likely compact configuration to realize both high efficiency and high gain (approx. 40 dB) is a 5-6 cavity design focused by an electromagnet. The basic klystron efficiency cannot be expected to exceed 70-75% without collector depression. It was estimated that the net benefit of a 5 stage collector over a 2 stage collector is between 1.5 and 3.5 kW per tube. A modulating anode is incorporated in the design to enable rapid shutoff of the beam current in case the r.f. drive should be removed

Microwave system performance summary

The design of the microwave system for the solar power satellite is described. Design modifications recommended include changes in phase control to the power module level, a reduction in allowable amplitude jitter, the use of metal matrix waveguides, and sequences for startup/shutdown procedures. Investigations into reshaping the beam pattern to improve overall rectenna collection efficiency and improve sidelobe control are surveyed

Perioperative Nutrition

Modern perioperative care is making steady advances in achieving optimal recovery for patients using the concept of early recovery after surgery (ERAS). Perioperative nutrition plays an important part in ERAS care and opportunities for nutritional interventions present for weeks up to hours before an operation, as well as in the postoperative period. Despite that malnutrition and suboptimal nutrition in surgical patients, particularly in those presenting with cancer, is very common

SPS fiber optic link assessment

Fiber optic technology was tentatively selected in the SPS baseline design to transmit a stable phase reference throughout microwave array. Over a hundred thousand microwave modules are electronically steered by the phase reference signal to form the power beam at the ground receiving station. The initially selected IF distribution frequency of the phase reference signal was at 980 MHz or a submultiple of it. Fiber optics offers some significant advantages in view of the SPS application. Optical transmission is highly immune to EMI/RFI, which is expected to be severe when considering the low distribution power. In addition, there are savings in both mass, physical size, and potentially in cost

Rectenna system design

The function of the rectenna in the solar power satellite system is described and the basic design choices based on the desired microwave field concentration and ground clearance requirements are given. One important area of concern, from the EMI point of view, harmonic reradiation and scattering from the rectenna is also designed. An optimization of a rectenna system design to minimize costs was performed. The rectenna cost breakdown for a 56 w installation is given as an example

Reference System Description

Several candidate antenna configurations are evaluated in terms of weight, efficiency, and structural rigidity. Particular emphasis is given to the waveguide slot array and its application to solar power satellites SPS. The electronic aspects of an SPS specific waveguide slot array are defined

Lactate – from villain to guardian

Elevated plasma lactate level is a useful warning sign in patients presenting with a variety of critical illnesses. Our understanding of hyperlactatemia, however, has improved and we can no longer associate lactate itself with any harmful effects. Lactate is a crucial intracellular buffer, and a central molecule in the interorgan exchange of carbon and redox potential. While lactate levels correlate with severity of acidaemia in shock there is little evidence to support the commonly held view that its origin is mainly secondary to anaerobic metabolism because of reduced tissue oxygen delivery

Percutaneous dilatational tracheostomy versus surgical tracheostomy in critically ill patients: a systematic review and meta-analysis

INTRODUCTION: Tracheostomy is one of the more commonly performed procedures in critically ill patients yet the optimal method of performing tracheostomies in this population remains to be established. The aim of this study was to systematically review and quantitatively synthesize all randomized clinical trials (RCTs), comparing elective percutaneous dilatational tracheostomy (PDT) and surgical tracheostomy (ST) in adult critically ill patients with regards to major short and long term outcomes. METHODS: MEDLINE, EMBASE, CINAHL and the Cochrane Controlled Clinical Trials Register databases were searched to identify relevant studies. Additionally, bibliographies and selected conference proceedings were reviewed, and experts in the field and manufacturers of two PDT kits were contacted. Randomized clinical trials comparing any method of elective PDT to ST that included critically ill adults and reported at least one clinically relevant outcome were included. Data extracted included trial characteristics, measures of study validity, and clinically relevant outcomes. RESULTS: Seventeen RCTs involving 1,212 patients were included. Most PDTs used a multiple dilator technique and were performed in the intensive care unit (ICU). The pooled odds ratio (OR) for wound infection was 0.28 (95% confidence interval (CI), 0.16 to 0.49, p < 0.0005), indicating a significant reduction with PDT compared to ST. Overall, PDT was equivalent to ST for bleeding, major peri-procedural and long-term complications; however, subgroup analysis suggested PDT resulted in a lower incidence of bleeding (OR = 0.29 (95% CI 0.12 to 0.75, p = 0.01)) and death (OR = 0.71 (95% CI 0.50 to 1.0, p = 0.05)) when the STs were performed in the operating theatre. CONCLUSION: PDT reduces the overall incidence of wound infection and may further reduce clinical relevant bleeding and mortality when compared with ST performed in the operating theatre. PDT, performed in the ICU, should be considered the procedure of choice for performing elective tracheostomies in critically ill adult patients