Context. Co-rotating spots at different latitudes on the stellar surface generate periodic photometric variability and can be useful proxies for detecting differential rotation (DR). This is a major ...ingredient of the solar dynamo, but observations of stellar DR are very sparse. Because the Kepler space telescope steadily collects more data, we are interested in detecting DR using photometric information of a star. Aims. The main goal of this paper is to develop a fast method for determining stellar DR from photometric data. Methods. We ran an extensive Monte Carlo simulation of differentially rotating spotted stars with very different properties to investigate the detectability of DR. For different noise levels the resulting light curves were prewhitened using Lomb-Scargle periodograms to derive parameters for a global sine fit to detect periodicities. Results. We show under which conditions DR can successfully be detected from photometric data, and in which cases the light curve provides insufficient or even misleading information on the stellar rotation law. In our simulations, the most significant period P1out is on average 2.4% shorter than the actual spot rotation-rate. This period was detected in 96.2% of all light curves. The signature of DR is a second period close to P1out in our model. For the noise-free case, we found such a period in 64.2% of all stars. Calculating the measured latitudinal shear of two distinct spots αout, and comparing this with the known original spot rotation-rates shows that the real value is on average 3.2% lower. Comparing the total equator-to-pole shear α to αout, we find that α is underestimated by 8.8%, especially the detection of DR for stars with α < 6% is challenging. Finally, we applied our method to four differentially rotating Kepler stars and found close agreement with results from detailed modeling. Conclusions. The method we developed is capable of measuring stellar rotation periods and detecting DR with relatively high accuracy and is suitable for large data sets. We will apply our analysis to more Kepler data in a forthcoming paper.
We present the results of a blind exercise to test the recoverability of stellar rotation and differential rotation in Kepler light curves. The simulated light curves lasted 1000 d and included ...activity cycles, Sun-like butterfly patterns, differential rotation and spot evolution. The range of rotation periods, activity levels and spot lifetime were chosen to be representative of the Kepler data of solar-like stars. Of the 1000 simulated light curves, 770 were injected into actual quiescent Kepler light curves to simulate Kepler noise. The test also included five 1000-d segments of the Sun's total irradiance variations at different points in the Sun's activity cycle. Five teams took part in the blind exercise, plus two teams who participated after the content of the light curves had been released. The methods used included Lomb–Scargle periodograms and variants thereof, autocorrelation function and wavelet-based analyses, plus spot modelling to search for differential rotation. The results show that the ‘overall’ period is well recovered for stars exhibiting low and moderate activity levels. Most teams reported values within 10 per cent of the true value in 70 per cent of the cases. There was, however, little correlation between the reported and simulated values of the differential rotation shear, suggesting that differential rotation studies based on full-disc light curves alone need to be treated with caution, at least for solar-type stars. The simulated light curves and associated parameters are available online for the community to test their own methods.
The accurate determination of stellar rotation periods is important for estimating stellar ages and for understanding stellar activity and evolution. While rotation periods can be determined for ...about thirty thousand stars in the
Kepler
field, there are over one hundred thousand stars, especially with low photometric variability and irregular pattern of variations, for which rotational periods are unknown. Here we investigate the effect of metallicity on the detectability of rotation periods. This is done by synthesising light curves of hypothetical stars that are identical to our Sun with the exception of the metallicity. These light curves are then used as an input to the period determination algorithms. We find that the success rate for recovering the rotation signal has a minimum close to the solar metallicity value. This can be explained by the compensation effect of facular and spot contributions. In addition, selecting solar-like stars with near-solar effective temperature and photometric variability, and with metallicity between
M
/
H
= −0.35 and
M
/
H
= 0.35 from the
Kepler
sample, we analyse the fraction of stars for which rotational periods have been detected as a function of metallicity. In agreement with our theoretical estimate we find a local minimum for the detection fraction close to the solar metallicity. We further report rotation periods of 87 solar-like
Kepler
stars for the first time.
Context.
Total solar irradiance allows for the use of the Sun as a star for studying observations of stellar light curves from recent space missions.
Aims.
We aim to study how the mid-range ...periodicity observed in solar activity indices influences the total solar irradiance.
Methods.
We studied periodic variations of total solar irradiance based on SATIRE-S and SOHO/VIRGO data during solar cycles 23–24 on timescales of Rieger-type periodicity. Then we compared the power spectrum of oscillations in the total solar irradiance to those of sunspot and faculae data to determine their contributions.
Results.
Wavelet analyses of TSI data reveal strong peaks at 180 days and 115 days in cycle 23, while cycle 24 showed periods of 170 days and 145 days. There are several periods in the sunspot and faculae data that are not seen in total solar irradiance as they probably cancel each other out through simultaneous brightening (in faculae) and darkening (in sunspots). Rieger-type periodicity is probably caused by magneto-Rossby waves in the internal dynamo layer, where the solar cyclic magnetic field is generated. Therefore, the observed periods in the total solar irradiance and the wave dispersion relation allow us to estimate the dynamo magnetic field strength as 10–15 kG.
Conclusions.
Total solar irradiance can be used to estimate the magnetic field strength in the dynamo layer. This tool can be of importance in estimating the dynamo magnetic field strength of solar-like stars using light curves obtained by space missions.
Tropical cyclone damage potential, as currently defined by the Saffir–Simpson scale and the maximum sustained surface wind speed in the storm, fails to consider the area impact of winds likely to ...force surge and waves or cause particular levels of damage. Integrated kinetic energy represents a framework that captures the physical process of ocean surface stress forcing waves and surge while also taking into account structural wind loading and the spatial coverage of the wind. Integrated kinetic energy was computed from gridded, objectively analyzed surface wind fields of 23 hurricanes representing large and small storms. A wind destructive potential rating was constructed by weighting wind speed threshold contributions to the integrated kinetic energy, based on observed damage in Hurricanes Andrew, Hugo, and Opal. A combined storm surge and wave destructive potential rating was assigned according to the integrated kinetic energy contributed by winds greater than tropical storm force. The ratings are based on the familiar 1–5 range, with continuous fits to allow for storms as weak as 0.1 or as strong as 5.99.
After the birth of a child, many mothers and fathers experience postpartum mental disorders like depression, anxiety, obsessive-compulsive disorder, stress or other illnesses. This endangers the ...establishment of a secure attachment between the children and their primary caregivers. Early problems in parent-child interaction can have adverse long-term effects on the family and the child's well-being. In order to prevent a transgenerational transmission of mental disorders, it is necessary to evaluate psychotherapeutic interventions that target psychologically burdened parents of infants or toddlers. The aim of this trial is to investigate the efficacy of Parent-Infant-Psychotherapy (PIP) for mothers with postpartum mental disorder and their infants (0-12 months).
In this open, randomized controlled intervention trial 180 mother-infant-dyads will be included and randomly allocated to 12 sessions of PIP or care as usual. The interventions take place either in inpatient adult psychiatric departments or in outpatient settings with home visits. The primary outcome is the change in maternal sensitivity assessed by the Sensitivity subscale of the Emotional Availability Scale (EAS) through videotaped dyadic play-interactions after 6 weeks. Secondary outcomes are maternal psychopathology, stress, parental reflective functioning, infant development and attachment after 6 weeks and 12 months. In addition, maternal attachment (AAI) and reflective functioning (AAI) will be analyzed as potential moderators, and resource usage in the German health system as well as associated costs will be evaluated.
There is increasing demand for well-controlled studies on psychotherapeutic interventions in the postpartum period that do not only focus on particular risk groups. This randomized controlled trial (RCT) represents one of the first studies to investigate the efficacy of PIP in inpatient psychiatric departments and outpatient care centers in Germany. The results will fill knowledge gaps on the factors contributing to symptom reduction in postpartum mental disorders and improvements in mother-child relationships and help in developing preventive and therapeutic strategies for the fragmented German health care system.
German Register for Clinical Trials, ID: DRKS00016353.
Sedentary and inactive lifestyle continues to increase and is associated with a substantial economic burden in most industrialised countries. To implement effective physical activity interventions on ...a broad population basis, their cost-effectiveness needs to be evaluated.
To evaluate the cost-effectiveness of physical activity interventions targeted at healthy adults and to identify cost-effective intervention components.
Systematic review. Methods and
The search strategy in electronic databases identified relevant literature published until June 2008. We included studies investigating the cost-effectiveness of interventions aiming to promote physical activity behaviour in healthy adults. Two researchers independently assessed publications according to predefined inclusion criteria and with regard to methodological quality. Study characteristics and predefined outcome measures were extracted and costs per participant to become sufficiently active were compared between interventions.
Out of 6543 identified publications, eight studies investigating 11 intervention strategies met the inclusion criteria. There was substantial heterogeneity in study quality, intervention strategies and intervention effects. Behavioural interventions were able to promote physical activity, with participants meeting recommended levels of physical activity, for about 800 Euros per year. Environmental interventions and interventions targeted at general practitioners seemed to have the potential to be substantially more cost-effective.
There was evidence that current physical activity intervention strategies can be a cost-effective means of resource allocation. But, despite the growing literature on physical activity promotion, appropriate cost-effectiveness analyses are rare and the generalisability of presented findings is limited. Further research is warranted to investigate the cost-effectiveness of behavioural and environmental intervention strategies.
Purpose
The postnatal period is a vulnerable time for parents and children but epidemiological and health care utilisation data for Germany on parental mental health during early childhood is scarce. ...This protocol describes the rationale, aim and study design of a population-based cohort study to assess the occurrence and determinants of psychosocial stress and mental health disorders, as well as the use and cost of health care and social services in early childhood.
Methods
As part of the collaborative SKKIPPI project, we will contact a random sample of 30,000 infants listed in the residents’ registration offices of three German towns and we expect to include 6,000 mother–child pairs. Both parents are invited to fill out an online screening questionnaire. Mothers with indications of psychosocial stress will be interviewed to assess mental health disorders, regulatory problems of their children, as well as health care and social services utilisation, with a follow-up assessment after 6 months.
Results
After description of sociodemographic and health data, we will analyse occurrences, patterns, and potential determinants (maternal age, social status, household factors, migration status etc.) of psychosocial stress and mental health disorders in the mothers and their children in early childhood.
Conclusions
Our study will identify potential risk and protective factors for postnatal mental health and health care utilization of psychosocially burdened families. This will help to improve prevention and treatment strategies to strengthen the parent–child relationship, to reduce persisting vulnerability of children, and to improve health care and social services.
Trial registration
The study has been registered in the German Clinical Trial Registry on February 8th 2019 (DRKS-ID: DRKS00016653).
Nutritional intervention with oral nutritional supplements (ONS) has been shown to increase quality of life in malnourished patients. We investigated whether post-hospital supplementation with ONS is ...cost-effective according to international benchmarks in malnourished patients.
In total, 114 malnourished patients (50.6±16.1 years, 57 female) with benign gastrointestinal disease were included and randomised to receive either ONS for 3 months and dietary counselling at discharge (intervention, n=60) or only dietary counselling at discharge (control group, n=54). Nutritional status was assessed with Subjective Global Assessment. Intervention patients documented daily intake of ONS; quality of life was assessed with Short-Form (SF)-36 Health Survey and SF-36 values were transformed into health-status utilities. Quality-adjusted life years (QALYs) were calculated by adopting the area under the curve method. We used two different pricing scenarios for ONS (minimum price: euro2.30 and maximum: euro2.93/tetrapack). The incremental cost-effectiveness ratio (ICER) of supplementation with ONS was calculated for both price scenarios. All analyses were corrected for age and gender.
Intervention patients consumed 2.4±0.8 ONS per day. Intervention and control patients did not differ in their health status utilities at baseline (0.594±0.017 vs 0.619±0.018), but after 3 months, the health status utilities were significantly higher in intervention patients than in control patients (0.731±0.015 vs 0.671±0.016, P=0.028). Intervention was associated with significantly higher costs (ICER: euro9497 and euro12,099/additional QALY, respectively) but deemed cost-effective according to international thresholds (< euro50,000/QALY).
A 3-month intervention with ONS increases quality of life in malnourished patients. This treatment appears to be cost-effective according to international benchmarks.
During landfall of Hurricane Ivan on the Florida ’panhandle’ in 2004, pressure time-history data were recorded on multiple pressure sensors installed on the roofs of six single-family homes. An ...analysis approach was developed to determine the peak negative, mean, peak positive, and standard deviation of pressure coefficients for these datasets. This paper presents a comparison of the full scale pressure coefficients from one of these homes, which experienced sustained hurricane force winds, with the results of wind tunnel experiments on a 1:50 scale model of that home. It was determined that the wind tunnel and full-scale mean and rms pressure coefficients matched very closely at almost every monitored location on the roof, while the peak negative pressure coefficients in the wind tunnel study generally underestimated the full-scale values, consistent with observations from previous full-scale/wind tunnel comparative studies. Field-measured hurricane wind loads may prove useful for evaluating existing wind load provisions. However, recommendations in that regard are premature without the analyses of multiple homes in multiple storms, performed by more than one wind tunnel facility. Future work will focus on building such a joint study.
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