Inflatorinen kiintopistelogiikka ja polynomisen ajan vaativuusluokka

Tutkielmassa esitetään kuvailevan vaativuusteorian tulos inflatorisen kiintopistelogiikan ja polynomisen ajan vaativuusluokan yhteydestä. Tuloksen todistamiseen tarvittavat logiikan ja vaativuusteorian pohjatiedot käydään tutkielmassa läpi. Joukko-opin perusteet ja yleiset merkinnät toivotaan lukijalle entuudesta tutuiksi. Inflatorinen kiintopistelogiikka on ensimmäisen kertaluvun logiikan laajennus, johon on lisätty inflatoriseksi kiintopistekvantifioinniksi kutsuttu kaavanmuodostussääntö. Inflatorinen kiintopistekvantifiointi määrittelee relaation induktiivisesti ja sopii hyvin kuvailemaan tietokoneiden iteratiivisia ja rekursiivisia toimenpiteitä. Rajoittumalla äärellisiin järjestettyihin malleihin saadaan inflatorisen kiintopistelogiikan ilmaisuvoima vastaamaan vaativuusteorian polynomisen ajan vaativuusluokkaa. Vaativuusteoriassa käytetään Turingin koneita työkaluna ongelmien ratkaisemiseen tarvittavia resursseja arvioitaessa. Resurssivaativuuksiltaan samankaltaisia ongelmia luokitellaan vaativuusluokkiin. Polynomisen ajan vaativuusluokka on luokka kaikille ongelmille, jotka voidaan ratkaista syötteen pituudesta polynomisesti riippuvassa määrässä Turingin koneen laskennan askelia. Inflatorisen kiintopistelogiikan ja polynomisen ajan vaativuusluokan yhteyden osoittamiseksi tutkielmassa esitetään, kuinka kuvailla logiikan malleja Turingin koneilla ja Turingin koneita logiikan kaavoilla. Tarvittavien työkalujen esittelyjä seuraa tutkielman päätulos: inflatorinen kiintopistelogiikka karakterisoi polynomisen ajan vaativuusluokan. Lopuksi käydään läpi järjestyksen olettamisen tarpeellisuutta

Factors associated with first return to work and sick leave durations in workers with common mental disorders

Background: Associations are examined between socio-demographic, medical, work-related and organizational factors and the moment of first return to work (RTW) (within or after 6 weeks of sick leave) and total sick leave duration in sick leave spells due to common mental disorders. Methods: Data are derived from a Dutch database, build to provide reference data for sick leave duration for various medical conditions. The cases in this study were entered in 2004 and 2005 by specially trained occupational health physicians, based on the physician's assessment of medical and other factors. Odds ratios for first RTW and sick leave durations are calculated in logistic regression models. Results: Burnout, depression and anxiety disorder are associated with longer sick leave duration. Similar, but weaker associations were found for female sex, being a teacher, small company size and moderate or high psychosocial hazard. Distress is associated with shorter sick leave duration. Medical factors, psychosocial hazard and company size are also and analogously associated with first RTW. Part-time work is associated with delayed first RTW. The strength of the associations varies for various factors and for different sick leave durations. Conclusion: The medical diagnosis has a strong relation with the moment of first RTW and the duration of sick leave spells in mental disorders, but the influence of demographic and work-related factors should not be neglected

Unemployment and retirement and ill-health: a cross-sectional analysis across European countries

Objective To determine the associations between different measures of health and labor market position across ten European countries. Methods We studied 11,462 participants of the Survey on Health and Ageing in Europe (SHARE) who were 50–64 years old. Logistic regression was used to calculate the associations between health and other determinants and being retired, unemployed, or a homemaker. Results A large variation across European countries was observed for the proportion of persons 50–65 years with paid employment, varying among men from 42% in Austria to 75% in Sweden and among women from 22% in Italy to 69% in Sweden. Among employed workers 18% reported a poor health, whereas this proportion was 37% in retirees, 39% in unemployed persons, and 35% in homemakers. A perceived poor health was strongly associated with non-participating in labor force in most European countries. A lower education, being single, physical inactivity and a high body mass index were associated with withdrawal from the labor force. Long-term illnesses such as depression, stroke, diabetes, chronic lung disease, and musculoskeletal disease were significantly more common among those persons not having paid employment. Conclusion In many European countries a poor health, chronic diseases, and lifestyle factors were associated with being out of the labor market. The results of this study suggest that in social policies to encourage employment among older persons the role of ill-health and its influencing factors needs to be incorporated

Knee complaints and consequences on work status; a 10-year follow-up survey among floor layers and graphic designers

<p>Abstract</p> <p>Background</p> <p>The purpose of the study was to examine if knee complaints among floor layers predict exclusion from the trade.</p> <p>Methods</p> <p>In 1994/95 self-reported data were obtained from a cohort of floor layers and graphic designers with and without knee straining work activities, respectively. At follow-up in 2005 the questionnaire survey was repeated. The study population consisted of 81 floor layers and 173 graphic designers who were presently working in their trades at baseline (1995). All participants were men aged 36–70 years in 2005.</p> <p>We computed the risk of losing gainful employment in the trade according to occurrence of knee complaints at baseline, using Cox proportional hazard regression adjusted for a number of potential confounding variables. Moreover, the crude and adjusted odds risk ratio for knee complaints according to status of employment in the trade were computed, using graphic designers as reference.</p> <p>Results</p> <p>A positive but non-significant association between knee complaints lasting more than 30 days the past 12 months and exclusion from the trade was found among floor layers (Hazard Ratio = 1.4, 95% CI = 0.6–3.5).</p> <p>The frequency of self-reported knee complaints was lower among floor layers presently at work in the trade in year 2005 (26.3%) compared with baseline in 1995 (41.1%), while the opposite tendency was seen among graphic designers (20.7% vs. 10.7%).</p> <p>Conclusion</p> <p>The study suggests that knee complaints are a risk factor for premature exclusion from a knee demanding trade. However, low power of the study precludes strong conclusions. The study also indicates a healthy worker effect among floor layers and a survivor effect among graphic designers.</p

Work-Family Conflict and Work Exit in Later Career Stage.

This study investigated relationships between work–family conflict and routes of later-life work exit

The Associations Between Retirement and Cardiovascular Disease Risk Factors in China: A 20-Year Prospective Study

Despite China's being the largest and most rapidly aging country in the world, there have been no longitudinal studies investigating the relationship between retirement and cardiovascular disease risk factors in China. In this study, we assessed the associations between retirement and systolic blood pressure, diastolic blood pressure, waist circumference, body mass index, smoking status, and alcohol consumption over a 17-year period both before and after retirement among 1,084 people (41.3% women) who participated in the China Health and Nutrition Survey (1991-2011) at least once prior to the year in which they retired and at least once afterward. Piecewise models centered at the year of retirement were applied. Retirement was accompanied by a reduction in diastolic blood pressure, a slowdown in the increase of both systolic blood pressure and waist circumference, and a reduction in the probability of being a heavy alcohol drinker. The association between retirement and blood pressure was stronger for men and for urban dwellers. No significant associations with body mass index or smoking were found. This study suggests that retirement may be beneficial for blood pressure, waist circumference, and alcohol consumption in the Chinese context. Understanding the potential health influence of retirement is essential, given plans to raise the retirement age in China

Pathways through which health influences early retirement: a qualitative study

Background: Due to the aeging of the population, there is a societal need for workers to prolong their working lives. In the Netherlands, many employees still leave the workforce before the official retirement age of 65. Previous quantitative research showed that poor self-perceived health is a risk factor of (non-disability) early retirement. However, little is known on how poor health may lead to early retirement, and why poor health leads to early retirement in some employees, but not in others. Therefore, the present qualitative study aims to identify in which ways health influences early retirement. Methods. Face-to-face semi-structured interviews were conducted with 30 employees (60-64 years) who retired before the official retirement age of 65. Participants were selected from the Study on Transitions in Employment, Ability and Motivation. The interviews were transcribed verbatim, a summary was made including a timeline, and the interviews were open coded. Results: In 15 of the 30 persons, health played a role in early retirement. Both poor and good health influenced early retirement. For poor health, four pathways were identified. First, employees felt unable to work at all due to health problems. Second, health problems resulted in a self-perceived (future) decline in the ability to work, and employees chose to retire early. Third, employees with health problems were afraid of a further decline in health, and chose to retire early. Fourth, employees with poor health retired early because they felt pushed out by their employer, although they themselves did not experience a reduced work ability. A good health influenced early retirement, since persons wanted to enjoy life while their health still allowed to do so. The financial opportunity to retire sometimes triggered the influence of poor health on early retirement, and often triggered the influence of good health. Employees and employers barely discussed opportunities to prolong working life. Conclusions: Poor and good health influence early retirement via several different pathways. To prolong working life, a dialogue between employers and employees and tailored work-related interventions may be helpful

Is There an Association between Long-Term Sick Leave and Disability Pension and Unemployment beyond the Effect of Health Status? – A Cohort Study

Background: Studies have shown that long-term sick leave is a strong predictor of disability pension. However, few have aimed to disentangle the effect of sick leave and of health status. The objective of this study was to investigate whether there is an association between long-term sick leave and disability pension and unemployment, when taking health status into account. Methods/Principal Findings: The study was based on the Stockholm Public Health Cohort, restricted to 13,027 employed individuals (45.9 % men) aged 18–59 in 2002 and followed until 2007. Hazard ratios (HR) with 95 % Confidence Interval (CI) were estimated by Cox regression models adjusting for socio-demographic factors and five measures of health status. Having been on long-term sick leave increased the risk of disability pension (HR 4.01; 95 % CI 3.19–5.05) and longterm unemployment (HR 1.45; 95 % CI 1.05–2.00), after adjustment for health status. The analyses of long-term sick leave due to specific illness showed that the increased risk for long-term unemployment was confined to the group on sick leave due to musculoskeletal (HR 1.70 95 % CI 1.00–2.89) and mental illness (HR 1.80 95 % CI 1.13–2.88) and further that there was an increased risk for short-term unemployment in the group on sick leave due to mental illness (HR1.57 95%CI 1.09–2.26). Conclusions/Significance: Long-term sick leave increases the risks of both disability pension and unemployment even when taking health status into account. The results support the hypothesis that long-term sick leave may start a process o