Operator ordering and causality

It is shown that causality violations [M. de Haan, Physica 132A, 375, 397 (1985)], emerging when the conventional definition of the time-normal operator ordering [P.L.Kelley and W.H.Kleiner, Phys.Rev. 136, A316 (1964)] is taken outside the rotating wave approximation, disappear when the amended definition [L.P. and S.S., Annals of Physics, 323, 1989 (2008)] of this ordering is used.Comment: References update

Statistics of Velocity from Spectral Data: Modified Velocity Centroids

We address the problem of studying interstellar turbulence using spectral line data. We find a criterion when the velocity centroids may provide trustworthy velocity statistics. To enhance the scope of centroids applications, we construct a measure that we term ``modified velocity centroids'' (MVCs) and derive an analytical solution that relates the 2D spectra of the modified centroids with the underlying 3D velocity spectrum. We test our results using synthetic maps constructed with data obtained through simulations of compressible magnetohydrodynamical (MHD) turbulence. We show that the modified velocity centroids (MVCs) are complementary to the the Velocity Channel Analysis (VCA) technique. Employed together, they make determining of the velocity spectral index more reliable and for wider variety of astrophysical situations.Comment: 4 pages, 1 figure, Accepted for publication in ApJ Letters. minor change

Gauss sum factorization with cold atoms

We report the first implementation of a Gauss sum factorization algorithm by an internal state Ramsey interferometer using cold atoms. A sequence of appropriately designed light pulses interacts with an ensemble of cold rubidium atoms. The final population in the involved atomic levels determines a Gauss sum. With this technique we factor the number N=263193.Comment: 4 pages, 5 figure

Trajectories of self-rated health before and after retirement: evidence from two cohort studies

OBJECTIVES: Previous studies have produced conflicting findings on the health consequences of retirement. We aimed at identifying trajectories of self-rated health over retirement transition using repeated measurements and examined which preretirement factors predicted membership to each trajectory. METHODS: The study population consisted of Finnish public sector employees from two independent cohorts (Finnish Public Sector Study (FPS), n=5776 with a 4-year follow-up interval; and Finnish Retirement and Aging Study (FIREA), n=2796 with a 1-year follow-up interval). Both cohorts included assessment of self-rated health one to three times before and one to three times after retirement (average number of measurement points: 3.7 in FPS and 3.5 in FIREA). We used latent trajectory analysis to identify trajectories of self-rated health. RESULTS: In both cohorts four similar trajectories were identified: 'Sustained good health' (47% in FPS and 74% in FIREA), 'From good to suboptimal health' (19% and 6%), 'From suboptimal to good health' (14% and 8%) and 'Sustained suboptimal health' (20% and 12%). There were more women and persons in high occupational status in the 'From suboptimal to good health' trajectory group when compared with 'Sustained suboptimal health' trajectory group in FPS. Those in the trajectory 'From good to suboptimal health' had lower occupational status and higher job strain in comparison with those in the 'Sustained good health' trajectory in both cohorts. CONCLUSIONS: A large majority of public sector employees maintain their perceived health status during retirement transition. Adverse trajectory in self-rated health relate to low occupational status and work-related stressors

Diet quality as a predictor of cardiometabolic disease-free life expectancy: the Whitehall II cohort study

Background: Poor diet quality has been linked to increased risk of many chronic diseases and premature mortality. Less research has considered dietary habits in relation to disease-free life expectancy. Objectives: Our objective was to investigate the association of diet quality with cardiometabolic disease–free life expectancy between ages 50 and 85 y. Methods: Diet quality of 8041 participants of the Whitehall II cohort study was assessed with the Alternative Healthy Eating Index 2010 (AHEI-2010) in 1991–1994, 1997–1999, and 2002–2004. The measurement of diet quality closest to age 50 for each participant was used. We utilized repeat measures of cardiometabolic disease (coronary heart disease, stroke, and type 2 diabetes) from the first observation when participants were aged ≥50 y. Multistate life table models with covariates age, gender, occupational position, smoking, physical activity, and alcohol consumption were used to estimate total and sex-specific cardiometabolic disease–free life expectancy from age 50 to 85 y for each AHEI-2010 quintile, where the lowest quintile represents unhealthiest dietary habits and the highest quintile the healthiest habits. Results: The number of cardiometabolic disease–free life-years after age 50 was 23.9 y (95% CI: 23.0, 24.9 y) for participants with the healthiest diet, that is, a higher score on the AHEI-2010, and 21.4 y (95% CI: 20.6, 22.3 y) for participants with the unhealthiest diet. The association between diet quality and cardiometabolic disease–free life expectancy followed a dose–response pattern and was observed in subgroups of participants of different occupational position, BMI, physical activity level, and smoking habit, as well as when participants without cardiometabolic disease at baseline were excluded from analyses. Conclusions: Healthier dietary habits are associated with cardiometabolic disease–free life expectancy between ages 50 and 85

Change in Job Strain as a Predictor of Change in Insomnia Symptoms: Analyzing Observational Data as a Non-randomized Pseudo-Trial

Study objectives: To examine whether change in job strain leads to change in insomnia symptoms. Methods: Among 24873 adults (82% women, mean age 44 years) who participated in a minimum of three consecutive study waves (2000–2012), job strain was assessed at the first and second wave and insomnia symptoms at all three waves. We analyzed observational data as a “pseudo-trial” including participants with no job strain in the first wave and no insomnia symptoms in the first and second wave (n = 7354) to examine whether the onset of job strain between the first and second waves predicted the onset of insomnia symptoms in the third wave. We used a corresponding approach, including those with job strain in the first wave and insomnia symptoms in the first and second wave (n = 2332), to examine whether the disappearance of job strain between the first two waves predicted remission of insomnia symptoms in the third wave. Results: The onset of job strain predicted the onset of subsequent insomnia symptoms after adjustment for sex, age, marital status, education, smoking, physical activity, alcohol consumption, body mass index, and comorbidities (odds ratio compared to no onset of job strain 1.32, 95% CI 1.16–1.51). The disappearance of job strain was associated with lower odds of repeated insomnia symptoms (odds ratio compared to no disappearance of job strain 0.78, 95% CI 0.65–0.94). Further adjustment for shift work or sleep apnea did not change these associations. Conclusions: These results suggest that job strain is a modifiable risk factor for insomnia symptoms

Quantum statistics of atoms in microstructures

This paper proposes groove-like potential structures for the observation of quantum information processing by trapped particles. As an illustration the effect of quantum statistics at a 50-50 beam splitter is investigated. For non-interacting particles we regain the results known from photon experiments, but we have found that particle interactions destroy the perfect bosonic correlations. Fermions avoid each other due to the exclusion principle and hence they are far less sensitive to particle interactions. For bosons, the behavior can be explained with simple analytic considerations which predict a certain amount of universality. This is verified by detailed numerical calculations.Comment: 18 pages incl. 13 figure

Adiabatic transfer of light in a double cavity and the optical Landau-Zener problem

We analyze the evolution of an electromagnetic field inside a double cavity when the difference in length between the two cavities is changed, e.g. by translating the common mirror. We find that this allows photons to be moved deterministically from one cavity to the other. We are able to obtain the conditions for adiabatic transfer by first mapping the Maxwell wave equation for the electric field onto a Schroedinger-like wave equation, and then using the Landau-Zener result for the transition probability at an avoided crossing. Our analysis reveals that this mapping only rigorously holds when the two cavities are weakly coupled (i.e. in the regime of a highly reflective common mirror), and that, generally speaking, care is required when attempting a hamiltonian description of cavity electrodynamics with time-dependent boundary conditions.Comment: 24 pages, 18 figures. Version 2 includes a new section (Sec. VIII) on the regimes of validity of the Schroedinger-like equations and also of the adiabatic approximation, together with a new figure (Fig. 10). The discussion section (Sec. XI) has also been enhance