Linköping University

About: Linköping University is a education organization based out in Linköping, Sweden. It is known for research contribution in the topics: Population & Health care. The organization has 15671 authors who have published 50013 publications receiving 1542189 citations.

Climate-sensitive northern lakes and ponds are critical components of methane release

Abstract: Lakes and ponds represent one of the largest natural sources of the greenhouse gas methane. By surface area, almost half of these waters are located in the boreal region and northwards. A synthesis ...

Massive MIMO Has Unlimited Capacity

Abstract: The capacity of cellular networks can be improved by the unprecedented array gain and spatial multiplexing offered by Massive MIMO. Since its inception, the coherent interference caused by pilot contamination has been believed to create a finite capacity limit, as the number of antennas goes to infinity. In this paper, we prove that this is incorrect and an artifact from using simplistic channel models and suboptimal precoding/combining schemes. We show that with multicell MMSE precoding/combining and a tiny amount of spatial channel correlation or large-scale fading variations over the array, the capacity increases without bound as the number of antennas increases, even under pilot contamination. More precisely, the result holds when the channel covariance matrices of the contaminating users are asymptotically linearly independent, which is generally the case. If also the diagonals of the covariance matrices are linearly independent, it is sufficient to know these diagonals (and not the full covariance matrices) to achieve an unlimited asymptotic capacity.

The Swedish rectal cancer registry

Abstract: Background: An audit of all patients with rectal cancer in Sweden was launched in 1995. This is the first report from the Swedish Rectal Cancer Registry (SRCR). Methods: Between 1995 and 2003, 13 434 patients treated for adenocarcinoma of the rectum were registered with the SRCR, there were approximately 1500 new patients annually. Results: Approximately half had an anterior resection, a quarter an abdominoperineal resection and 15 per cent a Hartmann's procedure. The median 30-day postoperative mortality rate was 2.4 per cent and the overall postoperative morbidity rate was 35.0 per cent. The 5-year cancer-specific survival rate was 62.3 percent. The 5-year relative survival rate was 70.1 percent after anterior resection, 59.8 per cent after abdominoperineal resection and 39.8 per cent after a Hartmann's procedure. The crude 5-year local recurrence rate was 9.5 per cent overall, 6.1 per cent after preoperative radiotherapy and 11.4 per cent after surgery alone. For 3868 patients who had a locally curative procedure the local recurrence rate was 7-4 per cent overall, 5.9 per cent for those who had radiotherapy and 10.2 per cent for those who did not. The local recurrence rate was 2.9 per cent (28 of 968) for stage I disease, 7.9 per cent (112 of 1418) for stage II, 13.9 per cent (188 of 1357) for stage III and 8.5 per cent (45 of 532) for stage IV. Conclusion: These good population-based results are due, in part, to the nationwide prospective quality assurance registration. Copyright © 2007 British Journal of Surgery Society Ltd Published by John Wiley & Sons Ltd.