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

Non-decision aid modified least mean square algorithm for joint blind equalization and carrier recovery in optical coherent receiver

We propose and demonstrate a new Non-Decision Aid Modified Least Mean Square (NDA-MLMS) algorithm for joint blind equalization and carrier recovery. The bit error rate (BER) of 10-3 is achieved with less than 1.9dB OSNR penalty for 14Gbaud 4-QAM system after 100km transmission and 500 KHz linewidth laser. © OSA 2012

Low complexity blind level discrimination carrier phase recovery algorithm in optical coherent receiver

We propose and demonstrate a low complexity blind Level Discrimination Carrier Recovery Algorithm (LD-CRA) for optical coherent receivers.Through optimization of step size parameter we found that LD-CRA has below 2 dB OSNR penalty for 14Gbaud 16-QAM signal for 600 kHz line width laser. © OSA 2012

Equalization &amp; carrier recovery for 112Gbps optical coherent system with HEX-16-QAM modulation

We propose and demonstrate a new 112 Gbps Polarization division Multiplexing digital optical coherent systems with hexagonal 16-QAM (HEX-16-QAM) modulation. In our proposed system we use decision directed dispersion compensation algorithm which is Least Mean Square (LMS) algorithm and single tap decision directed carrier recovery algorithm. We compare the HEX-16-QAM systems with 16-QAM system for uncompensated transmission. Our analysis result found that HEX-16-QAM can achieve bit error rate (BER) of 1.5×10-4 whereas square 16-QAM BER is 5×10-4 for uncompensated 500-km transmission at 25 dB OSNR. Propose system achieve 0.3 dB OSNR penalty with compare to square 16-QAM system. © 2012 IEEE

Blind Level Discrimination Carrier Recovery Algorithm for 16-QAM optical coherent communication system

We propose and demonstrate a new blind carrier recovering technique, named, Level Discrimination Carrier Recovery Algorithm (LD-CRA) for optical coherent receiver. Our proposed single tap LD-CRA can blindly compensate the laser phase noise without using any training sequence. Our analysis result found that for 300 KHz linewidth laser, the OSNR penalty is below 1.4dB at 10-3 bit error rate (BER) which has same as the decision directed single tap filter. © 2012 IEEE