Testing turbulent closure models with convection simulations

We compare simple analytical closure models of homogeneous turbulent Boussinesq convection for stellar applications with three-dimensional simulations. We use simple analytical closure models to compute the fluxes of angular momentum and heat as a function of rotation rate measured by the Taylor number. We also investigate cases with varying angles between the angular velocity and gravity vectors, corresponding to locating the computational domain at different latitudes ranging from the pole to the equator of the star. We perform three-dimensional numerical simulations in the same parameter regimes for comparison. The free parameters appearing in the closure models are calibrated by two fitting methods using simulation data. Unique determination of the closure parameters is possible only in the non-rotating case or when the system is placed at the pole. In the other cases the fit procedures yield somewhat differing results. The quality of the closure is tested by substituting the resulting coefficients back into the closure model and comparing with the simulation results. To eliminate the possibilities that the results obtained depend on the aspect ratio of the simulation domain or suffer from too small Rayleigh numbers we performed runs varying these parameters. The simulation data for the Reynolds stress and heat fluxes broadly agree with previous compressible simulations. The closure works fairly well with slow and fast rotation but its quality degrades for intermediate rotation rates. We find that the closure parameters depend not only on rotation rate but also on latitude. The weak dependence on Rayleigh number and the aspect ratio of the domain indicates that our results are generally validComment: 21 pages, 9 figures, submitted to Astron. Nach

Angular momentum transport in convectively unstable shear flows

Angular momentum transport owing to hydrodynamic turbulent convection is studied using local three dimensional numerical simulations employing the shearing box approximation. We determine the turbulent viscosity from non-rotating runs over a range of values of the shear parameter and use a simple analytical model in order to extract the non-diffusive contribution (Lambda-effect) to the stress in runs where rotation is included. Our results suggest that the turbulent viscosity is of the order of the mixing length estimate and weakly affected by rotation. The Lambda-effect is non-zero and a factor of 2-4 smaller than the turbulent viscosity in the slow rotation regime. We demonstrate that for Keplerian shear, the angular momentum transport can change sign and be outward when the rotation period is greater than the turnover time, i.e. when the Coriolis number is below unity. This result seems to be relatively independent of the value of the Rayleigh number.Comment: 10 pages, 12 figures, published version. Version with higher resolution figures can be found at http://www.helsinki.fi/~kapyla/publ.htm

Chemical exchange saturation transfer MRI shows low cerebral 2-deoxy-D-glucose uptake in a model of Alzheimer's Disease

Glucose is the central nervous system's only energy source. Imaging techniques capable to detect pathological alterations of the brain metabolism are useful in different diagnostic processes. Such techniques are also beneficial for assessing the evaluation efficacy of therapies in pre-clinical and clinical stages of diseases. Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) is a possible alternative to positron emission tomography (PET) imaging that has been widely explored in cancer research in humans and animal models. We propose that pathological alterations in brain 2-deoxy-D-glucose (2DG) uptake, typical of neurodegenerative diseases, can be detected with CEST MRI. Transgenic mice overexpressing a mutated form of amyloid precusrsor protein (APP23), a model of Alzheimer's disease, analyzed with CEST MRI showed a clear reduction of 2DG uptake in different brain regions. This was reminiscent of the cerebral condition observed in Alzheimer's patients. The results indicate the feasibility of CEST for analyzing the brain metabolic state, with better image resolution than PET in experimental models

Mean-field closure parameters for passive scalar turbulence

Peer reviewe

Mental Health and Traumatization of Newly Arrived Asylum Seeker Adults in Finland: A Population-Based Study

Asylum seekers frequently experience potentially traumatic events (PTEs), but the type and frequency vary depending on the country of origin. The cumulative effect of multiple PTEs and other stressors expose asylum seekers to a significant risk of mental ill health. The aim of the study was to examine the prevalence of PTEs, depression and anxiety symptoms, risk for psychological trauma, psychotropic medication use and previous mental health diagnoses among adult asylum seekers in the Asylum Seekers Health and Wellbeing (TERTTU) Survey (n = 784 respondents, participation rate 78.6%). A substantial majority (88.7%, 95% CI 86.9–90.3) of asylum seekers reported one or more PTEs before arriving to Finland. PTEs during the asylum-seeking journey were reported at 12.0% (95% CI 10.7–13.4), however, when examined by region of origin, the proportion was 34.5% (95% CI 29.5–39.8) for asylum seekers from Africa (excluding North Africa). Significant symptoms of depression were reported by 41.7% (95% CI 39.6–43.9) of asylum seekers and symptoms of anxiety by 34.2% (95% CI 32.1–36.2). Half of the asylum seekers were assessed as having at least a medium-risk for psychological trauma. Prevalence rates were higher among females and asylum seekers from Africa. This study highlights the importance of using screening tools to identify asylum seekers with severe mental health problems that may need referral to further assessment and treatment. Asylum seekers from Africa (excluding North Africa) should be given additional attention in initial health screenings and examinations

Hexyl aminolevulinate, 5-aminolevulinic acid nanoemulsion, and methyl aminolevulinate in photodynamic therapy of non-aggressive basal cell carcinomas: A non-sponsored, randomized, prospective and double-blinded trial

Abstract Background In the photodynamic therapy (PDT) of non-aggressive basal cell carcinomas (BCCs), 5-aminolevulinic acid nanoemulsion (BF-200ALA) has shown non-inferior efficacy when compared with methyl aminolevulinate (MAL), a widely used photosensitizer. Hexyl aminolevulinate (HAL) is an interesting alternative photosensitizer. To our knowledge, this is the first study using HAL-PDT in the treatment of BCCs. Objectives To compare the histological clearance, tolerability (pain and post-treatment reaction), and cosmetic outcome of MAL, BF-200 ALA, and low-concentration HAL in the PDT of non-aggressive BCCs. Methods Ninety-eight histologically verified non-aggressive BCCs met the inclusion criteria, and 54 patients with 95 lesions completed the study. The lesions were randomized to receive LED-PDT in two repeated treatments with MAL, BF-200 ALA, or HAL. Efficacy was assessed both clinically and confirmed histologically at three months by blinded observers. Furthermore, cosmetic outcome, pain, post-treatment reactions fluorescence, and photobleaching were evaluated. Results According to intention-to-treat analyses, the histologically confirmed lesion clearance was 93.8% (95% confidence interval [CI] = 79.9?98.3) for MAL, 90.9% (95% CI = 76.4?96.9) for BF-200 ALA, and 87.9% (95% CI = 72.7?95.2) for HAL, with no differences between the arms (p=0.84). There were no differences between the arms as regards pain, post-treatment reactions, or cosmetic outcome. Conclusions PDT with low-concentration HAL and BF-200 ALA have a similar efficacy, tolerability, and cosmetic outcome compared to MAL. HAL is an interesting new option in dermatological PDT, since good efficacy is achieved with a low concentration.Peer reviewe

Mental Health and Traumatization of Newly Arrived Asylum Seeker Adults in Finland: A Population-Based Study

Asylum seekers frequently experience potentially traumatic events (PTEs), but the type and frequency vary depending on the country of origin. The cumulative effect of multiple PTEs and other stressors expose asylum seekers to a significant risk of mental ill health. The aim of the study was to examine the prevalence of PTEs, depression and anxiety symptoms, risk for psychological trauma, psychotropic medication use and previous mental health diagnoses among adult asylum seekers in the Asylum Seekers Health and Wellbeing (TERTTU) Survey (n = 784 respondents, participation rate 78.6%). A substantial majority (88.7%, 95% CI 86.9–90.3) of asylum seekers reported one or more PTEs before arriving to Finland. PTEs during the asylum-seeking journey were reported at 12.0% (95% CI 10.7–13.4), however, when examined by region of origin, the proportion was 34.5% (95% CI 29.5–39.8) for asylum seekers from Africa (excluding North Africa). Significant symptoms of depression were reported by 41.7% (95% CI 39.6–43.9) of asylum seekers and symptoms of anxiety by 34.2% (95% CI 32.1–36.2). Half of the asylum seekers were assessed as having at least a medium-risk for psychological trauma. Prevalence rates were higher among females and asylum seekers from Africa. This study highlights the importance of using screening tools to identify asylum seekers with severe mental health problems that may need referral to further assessment and treatment. Asylum seekers from Africa (excluding North Africa) should be given additional attention in initial health screenings and examinations

Inspire: Challenging the lack of interest in physics among students

The Inspire project tested and analyzed the use of digital Learning resources (LR) in the field of Maths, Science and Technology (MST) in 63 schools in Austria, Germany, Italy, Lithuania and Spain. MST teachers used the LR from a pool of 60 resources (12 for Physics) in class and the effects on teachers and 5–18+ year old students were measured. We found the use of LR increases the understanding of students of MST and allows for differentiated learning within a class. LR have a larger impact on boys than girls, and it decreases with age. Overall, it appears the use of LR has a positive impact on MST education but special attention has to be placed on technical requirements and localization of the LR

Octet Baryon Magnetic Moments in the Chiral Quark Model with Configuration Mixing

The Coleman-Glashow sum-rule for magnetic moments is always fulfilled in the chiral quark model, independently of SU(3) symmetry breaking. This is due to the structure of the wave functions, coming from the non-relativistic quark model. Experimentally, the Coleman-Glashow sum-rule is violated by about ten standard deviations. To overcome this problem, two models of wave functions with configuration mixing are studied. One of these models violates the Coleman-Glashow sum-rule to the right degree and also reproduces the octet baryon magnetic moments rather accurately.Comment: 22 pages, RevTe