Coronal X-ray emission and planetary irradiation in HD 209458

HD 209458 is one of the benchmark objects in the study of hot Jupiter atmospheres and their evaporation through planetary winds. The expansion of the planetary atmosphere is thought to be driven by high-energy EUV and X-ray irradiation. We obtained new Chandra HRC-I data, which unequivocally show that HD 209458 is an X-ray source. Combining these data with archival XMM-Newton observations, we find that the corona of HD 209458 is characterized by a temperature of about 1 MK and an emission measure of 7e49 cm^-3, yielding an X-ray luminosity of 1.6e27 erg/s in the 0.124-2.48 keV band. HD 209458 is an inactive star with a coronal temperature comparable to that of the inactive Sun but a larger emission measure. At this level of activity, the planetary high-energy emission is sufficient to support mass-loss at a rate of a few times 1e10 g/s.Comment: Accepted for publication in A&

Fifteen years in the high-energy life of the solar-type star HD 81809. XMM-Newton observations of a stellar activity cycle

Aims. The data set of the long-term XMM-Newton monitoring program of HD 81809 is analyzed to study its X-ray cycle, to investigate if the latter is related to the chromospheric one, to infer the structure of the corona of HD 81809, and to explore if the coronal activity of HD 81809 can be ascribed to phenomena similar to the solar ones and, therefore, considered an extension of the solar case. Methods. We analyze the observations of HD 81809 performed with XMM-Newton with a regular cadence of 6 months from 2001 to 2016 and representing one of the longest available observational baseline ($\sim 15$~yr) for a solar-like star with a well-studied chromospheric cycle (with a period of $\sim 8$~yr). We investigate the modulation of coronal luminosity and temperature and its relation with the chromospheric cycle. We interpret the data in terms of a mixture of solar-like coronal regions, adopting a methodology originally proposed to study the Sun as an X-ray star. Results. The observations show a well-defined regular cyclic modulation of the X-ray luminosity that reflects the activity level of HD 81809. The data covers approximately two cycles of coronal activity; the modulation has an amplitude of a factor of $\sim 5$ (excluding evident flares, as in the June 2002 observation) and a period of $7.3\pm 1.5$~yr, consistent with that of the chromospheric cycle. We demonstrate that the corona of HD 81809 can be interpreted as an extension of the solar case and it can be modeled with a mixture of solar-like coronal regions along the whole cycle. The activity level is mainly determined by a varying coverage of very bright active regions, similar to cores of active regions observed in the Sun. Evidence of unresolved significant flaring activity is present especially in proximity of cycle maxima.Comment: 11 pages, 5 Figures, A&A accepte

Quality assurance in higher education - meta-evaluationof multi-stage evaluation procedures in Germany

Systematic procedures for quality assurance and improvement through evaluation have been in place in Western Europe since the mid 1980s and in Germany since the mid 1990s. As studies in Europe and beyond show that multi-stage evaluation procedures as the main quality assurance instrument for evaluation of teaching and learning in higher education institutions have proved reliable and have gained acceptance, in Germany (as well as in other countries) the evaluation of teaching and learning through internal and external evaluations has long come under the fire of criticism. Our results of the first comprehensive and representative investigation of procedures for the evaluation of teaching and learning in Germany show that former participants in the evaluations (reviewers and those reviewed) are satisfied all in all with the multi-stage procedure. They are convinced that the goals of quality assurance and improvement were achieved. Suggestions for improving the procedures target individual aspects, such as, for example, the composition of the review panel. Against this background, it makes sense to perform regular quality assessments of the procedures for quality assurance and improvemen

Psychophysiological correlates of peritraumatic dissociative responses in survivors of life-threatening cardiac events

The psychophysiological startle response pattern associated with peritraumatic dissociation (DISS) was studied in 103 survivors of a life-threatening cardiac event (mean age 61.0 years, SD 13.95). Mean time period since the cardiac event was 37 (79 IQD) months. All patients underwent a psychodiagnostic evaluation (including the Peritraumatic Dissociative Experiences Questionnaire) and a psychophysiological startle experience which comprised the delivery of 15 acoustic startle trials. Magnitude and habituation to trials were measured by means of electromyogram (EMG) and skin conductance responses (SCR). Thirty-two (31%) subjects were indexed as patients with a clinically significant level of DISS symptoms. High-level DISS was associated with a higher magnitude of SCR (ANOVA for repeated measures p = 0.017) and EMG (p = 0.055) and an impaired habituation (SCR slope p = 0.064; EMG slope p = 0.005) in comparison to subjects with no or low DISS. In a subgroup analysis, high-level DISS patients with severe post-traumatic stress disorder (PTSD; n = 11) in comparison to high-level DISS patients without subsequent PTSD (n = 19) exhibited higher EMG amplitudes during all trials (repeated measures analysis of variance IF = 5.511, p = 0.026). The results demonstrate exaggerated startle responses in SCR and EMG measures - an abnormal defensive response to high-intensity stimuli which indicates a steady state of increased arousal. DISS patients without PTSD exhibited balanced autonomic responses to the startle trials. DISS may, therefore, unfold malignant properties only in combination with persistent physiological hyperarousability. Copyright (C) 2002 S. Karger AG, Basel

Noninvasive monitoring of liver fat during treatment with GLP‐1 analogues and SGLT‐2 inhibitors in a real‐world setting

Introduction: Patients with NAFLD have a two‐fold increased risk of diabetes, and conversely, NAFLD affects up to 80% of patients with type 2 diabetes. Due to the co‐occurrence of both diseases and the lack of approved pharmacotherapy for NAFLD, the anti‐steatogenic potential of diabetes‐related drugs is being explored. In this study, we aim to monitor liver fat noninvasively during treatment with SGLT‐2 inhibitors or GLP‐1 analogues in a real‐world setting. Methods: Overall, 39 patients (49% women, age 57.7 ± 10.9 years) with type 2 diabetes and hepatic steatosis (defined by controlled attenuation parameter [CAP] values ≥ 215 dB/m) were observed for 6 months and routinely monitored with respect to hepatic fat contents and liver stiffness (VCTE); body composition (BIA); and blood biochemistry, including liver function tests (LFTs), serum lipids and glucose metabolism markers. Results: Median liver fat contents were significantly (P = .026) reduced by 9% in patients taking either SGLT‐2 (n = 22) or GLP‐1 (n = 17) for 6 months (absolute median CAP decrease: −32 dB/m [−58 to 32 dB/m]). In parallel, serum ALT and γ‐GT activities decreased significantly (P = .002 and P = .049, respectively). These improvements were accompanied by significant (P < .0001) changes to body weight and BMI (−2.5 ± 3.3 kg and −0.9 ± 1.2 kg/m2, respectively) and glucose homeostasis, with significant reductions in HbA1c and fasting plasma glucose (FDG) (both P < .0001). Of note, significant reductions of intrahepatic lipid contents occured in patients receiving SGLT‐2 inhibitors only. Conclusions: In this real‐world observational evaluation of fatty liver monitored noninvasively in patients with type 2 diabetes treated with either SGLT2 or GLP‐1, improvements in measures of hepatic steatosis, glucose and weight parameters were observed after 6 months, with significant reductions of intrahepatic lipid contents seen specifically in the SGLT2 subgroup

Image restoration using the chiral Potts spin-glass

We report on the image reconstruction (IR) problem by making use of the random chiral q-state Potts model, whose Hamiltonian possesses the same gauge invariance as the usual Ising spin glass model. We show that the pixel representation by means of the Potts variables is suitable for the gray-scale level image which can not be represented by the Ising model. We find that the IR quality is highly improved by the presence of a glassy term, besides the usual ferromagnetic term under random external fields, as very recently pointed out by Nishimori and Wong. We give the exact solution of the infinite range model with q=3, the three gray-scale level case. In order to check our analytical result and the efficiency of our model, 2D Monte Carlo simulations have been carried out on real-world pictures with three and eight gray-scale levels.Comment: RevTex 13 pages, 10 figure

A multi-wavelength view of the multiple activity cycles of ϵ\epsilon~Eridani

$\epsilon$ Eridani is a highly active young K2 star with an activity cycle of about three years established using Ca II H & K line index measurements (S_MWO). This relatively short cycle has been demonstrated to be consistent with X-ray and magnetic flux measurements. Recent work suggested a change in the cyclic behaviour. Here we report new X-ray flux and S_MWO measurements and also include S_MWO measurements from the historical Mount Wilson program. This results in an observational time baseline of over 50 years for the S_MWO data and of over 7 years in X-rays. Moreover, we include Ca II infrared triplet (IRT) index measurements (S_IRT) from 2013-2022 in our study. With the extended X-ray data set, we can now detect the short cycle for the first time using a periodogram analysis. Near-simultaneous S_MWO data and X-ray fluxes, which are offset by 20 days at most, are moderately strongly correlated when only the lowest activity state (concerning short-term variability) is considered in both diagnostics. In the S_MWO data, we find strong evidence for a much longer cycle of about 34 years and an 11-year cycle instead of the formerly proposed $12$-year cycle in addition to the known 3-year cycle. The superposition of the three periods naturally explains the recent drop in S_MWO measurements. The two shorter cycles are also detected in the S_IRT data, although the activity cycles exhibit lower amplitudes in the S_IRT than in the S_MWO data. Finally, the rotation period of $\epsilon$Eri can be found more frequently in the S_MWO as well as in the S_IRT data for times near the minimum of the long cycle. This may be explained by a scenario in which the filling factor for magnetically active regions near cycle maximum is too high to allow for notable short-term variations.Comment: accepted to A&

Thyroid Hormones Regulate Selenoprotein Expression and Selenium Status in Mice

Impaired expression of selenium-containing proteins leads to perturbed thyroid hormone (TH) levels, indicating the central importance of selenium for TH homeostasis. Moreover, critically ill patients with declining serum selenium develop a syndrome of low circulating TH and a central downregulation of the hypothalamus-pituitary-thyroid axis. This prompted us to test the reciprocal effect, i.e., if TH status would also regulate selenoprotein expression and selenium levels. To investigate the TH dependency of selenium metabolism, we analyzed mice expressing a mutant TH receptor α1 (TRα1+m) that confers a receptor-mediated hypothyroidism. Serum selenium was reduced in these animals, which was a direct consequence of the mutant TRα1 and not related to their metabolic alterations. Accordingly, hyperthyroidism, genetically caused by the inactivation of TRβ or by oral TH treatment of adult mice, increased serum selenium levels in TRα1+m and controls, thus demonstrating a novel and specific role for TRα1 in selenium metabolism. Furthermore, TH affected the mRNA levels for several enzymes involved in selenoprotein biosynthesis as well as serum selenoprotein P concentrations and the expression of other antioxidative selenoproteins. Taken together, our results show that TH positively affects the serum selenium status and regulates the expression of several selenoproteins. This demonstrates that selenium and TH metabolism are interconnected through a feed-forward regulation, which can in part explain the rapid parallel downregulation of both systems in critical illness

Variational method and duality in the 2D square Potts model

The ferromagnetic q-state Potts model on a square lattice is analyzed, for q>4, through an elaborate version of the operatorial variational method. In the variational approach proposed in the paper, the duality relations are exactly satisfied, involving at a more fundamental level, a duality relationship between variational parameters. Besides some exact predictions, the approach is very effective in the numerical estimates over the whole range of temperature and can be systematically improved.Comment: 20 pages, 5 EPS figure