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- Akerstedt, Torbjorn, et al.
(författare)
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Predicting long-term sickness absence from sleep and fatigue.
- 2007
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Ingår i: J Sleep Res. - : Wiley. - 0962-1105 .- 1365-2869. ; 16:4, s. 341-5
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Predicting long-term sickness absence from sleep and fatigue.Akerstedt T, Kecklund G, Alfredsson L, Selen J.Institute for Psychosocial Medicine, Public Health Sciences, Karolinska Institutet, Stockholm, Sweden. torbjorn.akerstedt@ipm.ki.seDisturbed or shortened sleep is prospectively related to disease. One might also expect that sickness absence would be another consequence but very little data seem to exist. The present study used 8300 individuals in a national sample to obtain information on reports of disturbed sleep and fatigue 1 year and merged this with data on long-term sickness absence 2 years later. A logistic regression analysis was applied to the data with adjustments for demographic and work environment variables. The results showed that individuals without registered sickness absence at the start had a higher probability of entering a period of long-term (>/=90 days, odds ratio [OR] = 1.24 with 95% confidence interval [CI] = 1.02-1.51) sickness absence 2 years later if they reported disturbed sleep at the start. The figure for fatigue was OR = 1.35 (CI = 1.14-1.60). When fatigue or disturbed sleep was separately excluded the OR increased to OR = 1.44 and OR = 1.47, respectively. Intermediate sickness absence (14-89 days) showed similar but slightly weaker results. The results indicate that disturbed sleep and fatigue are predictors of long-term absence and it is suggested that impaired sleep may be part of a chain of causation, considering its effects on fatigue.PMID: 18036078 [PubMed - in process]
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- Alfredsson, Joakim, et al.
(författare)
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Similar outcome with an invasive strategy in men and women with Non ST-Elevation Acute Coronary Syndromes
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Gender differences in benefit from an early invasive strategy in patients with Non ST-elevation Acute Coronary Syndromes (NSTE ACS) have been debated and results are conflicting. Some studies have even indicated harm for women associated with a routine invasive strategy. Method: We included 46 455 patients ( 14 819 women (32%) and 31 636 men (68%)) from The Register of Information and Knowledge about Swedish Heart Intensive care Admissions (RIKS-HIA), with a diagnosis of either unstable angina pectoris or non-ST-elevation myocardial infarction. All patients were admitted to intensive coronary care units in Sweden, between 2000 and 2006, and followed for 1 year. Adjustment for baseline differences between the genders was made. Results: In the non-invasive strategy arm relative risk (RR) of death was (women vs. men) 1.02 (95% CI, 0.94-1.11) and in the invasive strategy arm 1.12 (95% CI, 0.96-1.29). After adjustment for baseline differences between the genders with propensity score and discharge medication there was a trend towards lower mortality among women, RR 0.90 (95% CI, 0.82-0.99) in the early non-invasive group but still no difference in the early invasive cohort RR 0.90 (95% CI, 0.76-1.06). Results were similar with the combined end-point death/MI. The risk reduction with an invasive strategy was similar in women (RR 0.46 (95% CI 0.38-0.55)) and men (RR 0.45 (95% CI 0.40-0.52). Conclusion: In this large cohort of patients with NSTE ACS, reflecting real life management, women and men had similar outcome and similar benefit with an early invasive strategy.
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- Alfredsson, Lars-Inge, 1964-
(författare)
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VLSI Architectures and Arithmetic Operations with Application to the Fermat Number Transform
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The properties of arithmetic operations in Fermat integer quotient rings 2m+1, where m = 2t, are investigated. The arithmetic operations considered are mainly those involved in the computation of the Fermat number transform. We consider some ways of representing the binary coded integers in such rings and investigate VLSI architectures for arithmetic operations, with respect to the different element representations. The VLSI architectures are mutually compared with respect to area (A) and time (T) complexity and area-time performance (AT2). The VLSI model chosen is a linears witch-level RC model.In the polar representation, the nonzero elements of a field are represented by the powers of a primitive element of the field. In the thesis we particularly investigate the properties of arithmetic operations and their corresponding VLSI architectureswith respect to the polar representation of the elements of Fermat prime fields. Somenew results regarding the applicability of the Fermat number transform when usingthe polar representation are also presented.
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- Alfredsson, Lars, et al.
(författare)
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Jobstrain och riskfaktorer för hjärtkärlsjukdom
- 2002
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Ingår i: Psykosocial belastning och riskfaktorer för hjärt-kärlsjukdom. - Stockholm : Arbetslivsinstitutet. - 9170456410 ; , s. 1-2
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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- Alfredsson, Stefan, 1976-
(författare)
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TCP in Wireless Networks: Challenges, Optimizations and Evaluations
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents research on transport layer behavior in wireless networks. As the Internet is expanding its reach to include mobile devices, it has become apparent that some of the original design assumptions for the dominant transport protocol, TCP, are approaching their limits. A key feature of TCP is the congestion control algorithm, constructed with the assumption that packet loss is normally very low, and that packet loss therefore is a sign of network congestion. This holds true for wired networks, but for mobile wireless networks non-congestion related packet loss may appear. The varying signal power inherent with mobility and handover between base-stations are two example causes of such packet loss. This thesis provides an overview of the challenges for TCP in wireless networks together with a compilation of a number of suggested TCP optimizations for these environments. A TCP modification called TCP-L is proposed. It allows an application to increase its performance, in environments where residual bit errors normally give a degraded throughput, by making a reliability tradeoff. The performance of TCP-L is experimentally evaluated with an implementation in the Linux kernel. The transport layer performance in a 4G scenario is also experimentally investigated, focusing on the impact of the link layer design and its parameterization. Further, for emulation-based protocol evaluations, controlled packet loss and bit error generation is shown to be an important aspect.
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