151 research outputs found
Atmospheric ice nuclei in the Eyjafjallajökull volcanic ash plume
We have sampled atmospheric ice nuclei (IN) and aerosol in Germany and in Israel during spring 2010. IN were analyzed by the static vapor diffusion chamber FRIDGE, as well as by electron microscopy. During the Eyjafjallajökull volcanic eruption of April 2010 we have measured the highest ice nucleus number concentrations (>600 lâ1) in our record of 2 yr of daily IN measurements in central Germany. Even in Israel, located about 5000 km away from Iceland, IN were as high as otherwise only during desert dust storms. The fraction of aerosol activated as ice nuclei at â18 °C and 119% rhice and the corresponding area density of ice-active sites per aerosol surface were considerably higher than what we observed during an intense outbreak of Saharan dust over Europe in May 2008.
Pure volcanic ash accounts for at least 53â68% of the 239 individual ice nucleating particles that we collected in aerosol samples from the event and analyzed by electron microscopy. Volcanic ash samples that had been collected close to the eruption site were aerosolized in the laboratory and measured by FRIDGE. Our analysis confirms the relatively poor ice nucleating efficiency (at â18 °C and 119% ice-saturation) of such "fresh" volcanic ash, as it had recently been found by other workers. We find that both the fraction of the aerosol that is active as ice nuclei as well as the density of ice-active sites on the aerosol surface are three orders of magnitude larger in the samples collected from ambient air during the volcanic peaks than in the aerosolized samples from the ash collected close to the eruption site. From this we conclude that the ice-nucleating properties of volcanic ash may be altered substantially by aging and processing during long-range transport in the atmosphere, and that global volcanism deserves further attention as a potential source of atmospheric ice nuclei
Experimental determination of isotope enrichment factors â bias from mass removal by repetitive sampling
Application
of compound-specific stable isotope approaches often involves comparisons
of isotope enrichment factors (Δ). Experimental determination
of Δ-values is based on the Rayleigh equation, which relates
the change in measured isotope ratios to the decreasing substrate
fractions and is valid for closed systems. Even in well-controlled
batch experiments, however, this requirement is not necessarily fulfilled,
since repetitive sampling can remove a significant fraction of the
analyte. For volatile compounds the need for appropriate corrections
is most evident, and various methods have been proposed to account
for mass removal and for volatilization into the headspace. In this
study we use both synthetic and experimental data to demonstrate that
the determination of Δ-values according to current correction
methods is prone to considerable systematic errors even in well-designed
experimental setups. Application of inappropriate methods may lead
to incorrect and inconsistent Δ-values entailing misinterpretations
regarding the processes underlying isotope fractionation. In fact,
our results suggest that artifacts arising from inappropriate data
evaluation might contribute to the variability of published Δ-values.
In response, we present novel, adequate methods to eliminate systematic
errors in data evaluation. A model-based sensitivity analysis serves
to reveal the most crucial experimental parameters and can be used
for future experimental design to obtain correct Δ-values allowing
mechanistic interpretations
Kompetenzentwicklung und Bildungsentscheidungen im Vor- und Grundschulalter
"In den meisten soziologischen Theorien zu Bildungsungleichheiten gehen die Verfasser davon aus, dass unterschiedliche Schulleistungen vor allem Resultat unterschiedlicher familiĂ€rer Bedingungen im Hinblick auf kulturelles Kapital sind. Allerdings wird in neueren soziologischen Studien konzediert, dass Schulleistungen auch als Ergebnis der unterschiedlich ausgeprĂ€gten KompetenzgefĂŒge der Kinder zu betrachten sind. Wenn jedoch ĂŒberhaupt Kompetenzparameter in quantitative soziologische Analysen einflieĂen, dann meist in Form von Schulnoten. Diese sind aber nicht unbedingt ein valider Indikator fĂŒr die kindliche Kompetenzlage, sondern das Ergebnis eines lĂ€ngeren und komplexen Prozesses, in dem auch die Bedingungen in Familie, Kindergarten und Schule wirksam werden. Um die Herausbildung von schichtspezifischen Bildungswegen besser zu verstehen und abschĂ€tzen zu können, welcher Stellenwert den Kompetenzen der Kinder zukommt, ist es erforderlich, verschiedene Aspekte kindlicher Kompetenzen zu unterscheiden und diese ĂŒber einen lĂ€ngeren Zeitraum in ihrer AbhĂ€ngigkeit von familiĂ€ren und institutionellen Bedingungen zu untersuchen. In enger Zusammenarbeit von SoziologInnen, PsychologInnen und PĂ€dagogInnen wendet sich das BiKS-Projekt derzeit diesen Fragen zu. In dem Vortrag stellen sie zunĂ€chst die theoretische Konzeption und das Design der BiKS-Studie vor. Sodann thematisieren sie die Frage, wie in der modernen psychologischen Kompetenzforschung der Gegensatz zwischen angeborenem Potential und UmwelteinflĂŒssen diskutiert wird, und isolieren darauf aufbauend unterschiedliche Aspekte der kognitiven und sprachlichen Kompetenz. Danach prĂ€sentieren sie erste empirische Ergebnisse aus dem BiKS-SchullĂ€ngsschnitt und stellen dar, ob und in welcher Weise kindliche Kompetenzen und Schulnoten mit den familiĂ€ren Bedingungen kovariieren und auf die Formation von Bildungsentscheidungen einwirken." (Autorenreferat
Effects of a minimalâguided onâline intervention for alcohol misuse in Estonia: a randomized controlled trial
Background and aims: Estonia has one of the highest alcohol-attributable mortality rates within the European Union. The aim of this study was to estimate the efficacy of an on-line self-help intervention to reduce problem drinking at the population level.
Design: On-line open randomized controlled trial with an 8-week intervention and an active control group (intervention n = 303, control n = 286). Assessments took place at baseline and at 6 months follow-up.
Setting: On- and offline channels were used for population-based recruitment within a nation-wide prevention campaign in Estonia.
Participants: Inclusion criteria were age â„ 18 years, heavy drinking [Alcohol Use Disorders Identification (AUDIT) test score â„ 8], literacy in Estonian and at least weekly access to the internet; n = 589 participants were randomized (50% male, 1% other; mean age 37.86 years; 45% with higher level of education).
Intervention and comparator: The intervention consisted of 10 modules based on principles of cognitive-behavioral therapy and motivational interviewing. The active control group received access to a website with a self-test including personalized normative feedback and information for standard alcohol treatment.
Measurements: The primary outcome was AUDIT scores at 6 months follow-up adjusted for baseline scores.
Findings: Intention-to-treat analyses were applied. Missing data were addressed by using baseline observation carried forward (BOCF) and multiple imputation by chained equations (MI); 175 completed follow-up in the intervention group and 209 in the control group. AUDIT score at follow-up was significantly smaller in the intervention [BOCF mean = 13.91, standard deviation (SD) = 7.61, MI mean = 11.03, SD = 6.55] than control group (BOCF mean = 15.30, SD = 7.31; MI mean = 14.30, SD = 7.21), with a group difference of -1.38 [95% confidence interval (CI) = -2.58, -0.18], P = 0.02 for BOCF and -3.26 (95% CI = -2.01, -4.51), P < 0.001 for MI.
Conclusions: A randomized controlled trial has found that an on-line self-help intervention with minimal guidance was effective at reducing problem drinking in Estonia.
Keywords: AUDIT; Alcohol; Estonia; RCT; drinking; e-intervention; minimal guidance; self-hel
Human tumors instigate granulin-expressing hematopoietic cells that promote malignancy by activating stromal fibroblasts in mice
Systemic instigation is a process by which endocrine signals sent from certain tumors (instigators) stimulate BM cells (BMCs), which are mobilized into the circulation and subsequently foster the growth of otherwise indolent carcinoma cells (responders) residing at distant anatomical sites. The identity of the BMCs and their specific contribution or contributions to responder tumor growth have been elusive. Here, we have demonstrated that Scal(+)cKit(-) hematopoietic BMCs of mouse hosts bearing instigating tumors promote the growth of responding tumors that form with a myofibroblast-rich, desmoplastic stroma. Such stroma is almost always observed in malignant human adenocarcinomas and is an indicator of poor prognosis. We then identified granulin (GRN) as the most upregulated gene in instigating Scal(+)cKit(-) BMCs relative to counterpart control cells. The GRN(+) BMCs that were recruited to the responding tumors induced resident tissue fibroblasts to express genes that promoted malignant tumor progression; indeed, treatment with recombinant GRN alone was sufficient to promote desmoplastic responding tumor growth. Further, analysis of tumor tissues from a cohort of breast cancer patients revealed that high GRN expression correlated with the most aggressive triple-negative, basal-like tumor subtype and reduced patient survival. Our data suggest that GRN and the unique hematopoietic BMCs that produce it might serve as novel therapeutic targets
Interrelations between participant and intervention characteristics, process variables and outcomes in online interventions: A protocol for overarching analyses within and across seven clinical trials in ICare
Background: It is well known that web-based interventions can be effective treatments for various conditions. Less is known about predictors, moderators, and mediators of outcome and especially interrelations between participant and interventions characteristics, process variables and outcomes in online interventions. Clinical trials often lack statistical power to detect variables that affect intervention effects and their interrelations. Within ICare, we can investigate the interrelation of potential predictor and process variables in a large sample.
Method: The ICare consortium postulated a model of interrelations between participant and intervention characteristics, process variables and outcomes in online interventions. We will assess general and disorderspecific interrelations between characteristics of the intervention, characteristics of the participants, adherence, working alliance, early response, and intervention outcomes in a sample of over 7500 participants from seven clinical trials evaluating 15 online interventions addressing a range of mental health conditions and disorders, using an individual participant data meta-analyses approach.
Discussion/conclusion: Existing research tends to support the efficacy of online mental health interventions, but the knowledge base regarding factors that affect intervention effects needs to be expanded. The overarching analyses using data from the ICare intervention trials will add considerably to the evidence
Treatment Strategies and Outcome of the ExstrophyâEpispadias Complex in Germany: Data From the German CURE-Net
Introduction: To evaluate the impact of reconstructive strategies and post-operative management on short- and long-term surgical outcome and complications of classical bladder exstrophy (CBE) patients' comprehensive data of the multicenter German-wide Network for Congenital Uro-Rectal malformations (CURE-Net) were analyzed.
Methods: Descriptive analyses were performed between 34 prospectively collected CBE patients born since 2009, median 3 months old [interquartile range (IQR), 2â4 months], and 113 cross-sectional patients, median 12 years old (IQR, 6â21 years).
Results: The majority of included individuals were males (67%). Sixty-eight percent of the prospectively observed and 53% of the cross-sectional patients were reconstructed using a staged approach (p = 0.17). Although prospectively observed patients were operated on at a younger age, the post-operative management did not significantly change in the years before and after 2009. Solely, in prospectively observed patients, peridural catheters were used significantly more often (p = 0.017). Blood transfusions were significantly more frequent in males (p = 0.002). Only half of all CBE individuals underwent inguinal hernia repair. Cross-sectional patients after single-stage reconstructions showed more direct post-operative complications such as upper urinary tract dilatations (p = 0.0021) or urinary tract infections (p = 0.023), but not more frequent renal function impairment compared to patients after the staged approach (p = 0.42). Continence outcomes were not significantly different between the concepts (p = 0.51). Self-reported continence data showed that the majority of the included CBE patients was intermittent or continuous incontinent. Furthermore, subsequent consecutive augmentations and catheterizable stomata did not significantly differ between the two operative approaches. Urinary diversions were only reported after the staged concept.
Conclusions: In this German multicenter study, a trend toward the staged concept was observed. While single-stage approaches tended to have initially more complications such as renal dilatation or urinary tract infections, additional surgery such as augmentations and stomata appeared to be similar after staged and single-stage reconstructions in the long term
Grip strength values and cut-off points based on over 200,000 adults of the German National Cohort - a comparison to the EWGSOP2 cut-off points
BACKGROUND: The European Working Group on Sarcopenia in Older People (EWGSOP) updated in 2018 the cut-off points for low grip strength to assess sarcopenia based on pooled data from 12 British studies. OBJECTIVE: Comparison of the EWGSOP2 cut-off points for low grip strength to those derived from a large German sample. METHODS: We assessed the grip strength distribution across age and derived low grip strength cut-off points for men and women (peak mean -2.5âĂâSD) based on 200,389 German National Cohort (NAKO) participants aged 19â75 years. In 1,012 Cooperative Health Research in the Region of Augsburg (KORA)-Age participants aged 65â93 years, we calculated the age-standardised prevalence of low grip strength and time-dependent sensitivity and specificity for all-cause mortality. RESULTS: Grip strength increased in the third and fourth decade of life and declined afterwards. Calculated cut-off points for low grip strength were 29 kg for men and 18 kg for women. In KORA-Age, the age-standardised prevalence of low grip strength was 1.5Ă higher for NAKO-derived (17.7%) compared to EWGSOP2 (11.7%) cut-off points. NAKO-derived cut-off points yielded a higher sensitivity and lower specificity for all-cause mortality. CONCLUSIONS: Cut-off points for low grip strength from German population-based data were 2 kg higher than the EWGSOP2 cut-off points. Higher cut-off points increase the sensitivity, thereby suggesting an intervention for more patients at risk, while other individuals might receive additional diagnostics/treatment without the urgent need. Research on the effectiveness of intervention in patients with low grip strength defined by different cut-off points is needed
CRX controls retinal expression of the X-linked juvenile retinoschisis (RS1) gene
X-linked juvenile retinoschisis is a heritable condition of the retina in males caused by mutations in the RS1 gene. Still, the cellular function and retina-specific expression of RS1 are poorly understood. To address the latter issue, we characterized the minimal promoter driving expression of RS1 in the retina. Binding site prediction, site-directed mutagenesis, and reporter assays suggest an essential role of two nearby cone-rod homeobox (CRX)-responsive elements (CRE) in the proximal â177/+32 RS1 promoter. Chromatin immunoprecipitation associates the RS1 promoter in vivo with CRX, the coactivators CBP, P300, GCN5 and acetylated histone H3. Transgenic Xenopus laevis expressing a green fluorescent protein (GFP) reporter under the control of RS1 promoter sequences show that the â177/+32 fragment drives GFP expression in photoreceptors and bipolar cells. Mutating either of the two conserved CRX binding sites results in strongly decreased RS1 expression. Despite the presence of sequence motifs in the promoter, NRL and NR2E3 appear not to be essential for RS1 expression. Together, our in vitro and in vivo results indicate that two CRE sites in the minimal RS1 promoter region control retinal RS1 expression and establish CRX as a key factor driving this expression
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