394 research outputs found

    Fallstudie zur Erhaltung der Kulturlandschaft im Oberen Filstal durch Ziegenbeweidung

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    Due to the ongoing structural change in the German agricultural sector, the utilisation of numerous marginal production sites and production systems has been abandoned over the last decades. This development can be witnessed most severely in south-western Germany. One outstanding example is the juniper heathlands of the Swabian Alb, which have originally been formed by extensive goat- and sheep grazing systems. These cultural landscapes represent an important aspect for the regional development and the local recreation, which is an essential income source for the region. The focus of this case study has been the economical and ecological performance of a goat grazing system in comparison to modern mechanical landscape management

    An administration concept for the enterprise role-based access control model

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    Polarized Redundant-Baseline Calibration for 21 cm Cosmology Without Adding Spectral Structure

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    21 cm cosmology is a promising new probe of the evolution of visible matter in our universe, especially during the poorly-constrained Cosmic Dawn and Epoch of Reionization. However, in order to separate the 21 cm signal from bright astrophysical foregrounds, we need an exquisite understanding of our telescopes so as to avoid adding spectral structure to spectrally-smooth foregrounds. One powerful calibration method relies on repeated simultaneous measurements of the same interferometric baseline to solve for the sky signal and for instrumental parameters simultaneously. However, certain degrees of freedom are not constrained by asserting internal consistency between redundant measurements. In this paper, we review the origin of these "degeneracies" of redundant-baseline calibration and demonstrate how they can source unwanted spectral structure in our measurement and show how to eliminate that additional, artificial structure. We also generalize redundant calibration to dual-polarization instruments, derive the degeneracy structure, and explore the unique challenges to calibration and preserving spectral smoothness presented by a polarized measurement.Comment: 12 pages, 3 figures, updated to match the published MNRAS versio

    Does tumorigenesis select for or against mutations of the DNA repair-associated genes BRCA2 and MRE11?: Considerations from somatic mutations in microsatellite unstable (MSI) gastrointestinal cancers

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    BACKGROUND: The BRCA2 and MRE11 proteins participate in the repair of double-strand DNA breaks by homologous recombination. Germline BRCA2 mutations predispose to ovarian, breast and pancreatic cancer, while a germline MRE11 mutation is associated with an ataxia telangiectasia-like disorder. Somatic mutations of BRCA2 are rare in typical sporadic cancers. In tumors having microsatellite instability (MSI), somatic truncating mutations in a poly [A] tract of BRCA2 are reported on occasion. RESULTS: We analyzed gastrointestinal MSI cancers by whole gene BRCA2 sequencing, finding heterozygous truncating mutations in seven (47%) of 15 patients. There was no cellular functional defect in RAD51 focus-formation in three heterozygously mutated lines studied, although other potential functions of the BRCA2 protein could still be affected. A prior report of mutations in primary MSI tumors affecting the IVS5-(5–15) poly [T] tract of the MRE11 gene was confirmed and extended by analysis of the genomic sequence and protein expression in MSI cancer cell lines. Statistical analysis of the published MRE11 mutation rate in MSI tumors did not provide evidence for a selective pressure favoring biallelic mutations at this repeat. CONCLUSION: Perhaps conflicting with common suspicions, the data are not compatible with selective pressures during tumorigenesis promoting the functional loss of BRCA2 and MRE11 in MSI tumors. Instead, these data fit closely with an absence of selective pressures acting on BRCA2 and MRE11 gene status during tumorigenesis

    Soft-landing electrospray ion beam deposition of sensitive oligoynes on surfaces in vacuum

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    AbstractAdvances in synthetic chemistry permit the synthesis of large, highly functional, organic molecules. Characterizing the complex structure of such molecules with highly resolving, vacuum-based methods like scanning probe microscopy requires their transfer into the gas phase and further onto an atomically clean surface in ultrahigh vacuum without causing additional contamination. Conventionally this is done via sublimation in vacuum. However, similar to biological molecules, large synthetic compounds can be non-volatile and decompose upon heating. Soft-landing ion beam deposition using soft ionization methods represents an alternative approach to vacuum deposition. Using different oligoyne derivatives of the form of R1(CC)nR2, here we demonstrate that even sensitive molecules can be handled by soft-landing electrospray ion beam deposition. We generate intact molecular ions as well as fragment ions with intact hexayne parts and deposit them on clean metal surfaces. Scanning tunneling microscopy shows that the reactive hexayne segments of the molecules of six conjugated triple bonds are intact. The molecules agglomerate into ribbon-like islands, whose internal structure can be steered by the choice of the substituents. Our results suggest the use of ion beam deposition to arrange reactive precursors for subsequent polymerization reactions

    Temperature as a Circadian Marker in Older Human Subjects: Relationship to Metabolic Syndrome and Diabetes

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    Background: Circadian rhythms are characterized by approximate 24-hour oscillations in physiological and behavioral processes. Disruptions in these endogenous rhythms, most commonly associated with shift work and/or lifestyle, are recognized to be detrimental to health. Several studies have demonstrated a high correlation between disrupted circadian rhythms and metabolic disease. The aim of this study was to determine which metabolic parameters correlate with physiological measures of circadian temperature amplitude (TempAmp) and stability (TempStab). Methods: Wrist skin temperature was measured in 34 subjects (ages 50 to 70, including lean, obese, and diabetic subjects) every 10 minutes for 7 consecutive days. Anthropometric measures and fasting blood draws were conducted to obtain data on metabolic parameters: body mass index, hemoglobin A1C, triglycerides, cholesterol, high-density lipoprotein, and low-density lipoprotein. A history of hypertension and current blood pressure was noted. Results: Analysis of the data indicated a substantial reduction in TempAmp and TempStab in subjects with metabolic syndrome (three or more risk factors). To determine the impact of individual interdependent metabolic factors on temperature rhythms, stepwise multilinear regression analysis was conducted using metabolic syndrome measurements. Interestingly, only triglyceride level was consistently correlated by the analysis. Triglyceride level was shown to contribute to 33% of the variability in TempAmp and 23% of the variability in TempStab. Conclusion: Our results demonstrate that elevated triglycerides are associated with diminished TempAmp and TempStab in human subjects, and triglycerides may serve as a primary metabolic predictor of circadian parameters

    The asparagine-transamidosome from Helicobacter pylori: a dual-kinetic mode in non-discriminating aspartyl-tRNA synthetase safeguards the genetic code

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    Helicobacter pylori catalyzes Asn-tRNAAsn formation by use of the indirect pathway that involves charging of Asp onto tRNAAsn by a non-discriminating aspartyl-tRNA synthetase (ND-AspRS), followed by conversion of the mischarged Asp into Asn by the GatCAB amidotransferase. We show that the partners of asparaginylation assemble into a dynamic Asn-transamidosome, which uses a different strategy than the Gln-transamidosome to prevent the release of the mischarged aminoacyl-tRNA intermediate. The complex is described by gel-filtration, dynamic light scattering and kinetic measurements. Two strategies for asparaginylation are shown: (i) tRNAAsn binds GatCAB first, allowing aminoacylation and immediate transamidation once ND-AspRS joins the complex; (ii) tRNAAsn is bound by ND-AspRS which releases the Asp-tRNAAsn product much slower than the cognate Asp-tRNAAsp; this kinetic peculiarity allows GatCAB to bind and transamidate Asp-tRNAAsn before its release by the ND-AspRS. These results are discussed in the context of the interrelation between the Asn and Gln-transamidosomes which use the same GatCAB in H. pylori, and shed light on a kinetic mechanism that ensures faithful codon reassignment for Asn

    Using magnetic resonance imaging to measure head muscles: An innovative method to opportunistically determine muscle mass and detect sarcopenia

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    Background Sarcopenia is associated with multiple adverse outcomes. Traditional methods to determine low muscle mass for the diagnosis of sarcopenia are mainly based on dual-energy X-ray absorptiometry (DXA), whole-body magnetic resonance imaging (MRI) and bioelectrical impedance analysis. These tests are not always available and are rather time consuming and expensive. However, many brain and head diseases require a head MRI. In this study, we aim to provide a more accessible way to detect sarcopenia by comparing the traditional method of DXA lean mass estimation versus the tongue and masseter muscle mass assessed in a standard brain MRI. Methods The H70 study is a longitudinal study of older people living in Gothenburg, Sweden. In this cross-sectional analysis, from 1203 participants aged 70 years at baseline, we included 495 with clinical data and MRI images available. We used the appendicular lean soft tissue index (ALSTI) in DXA images as our reference measure of lean mass. Images from the masseter and tongue were analysed and segmented using 3D Slicer. For the statistical analysis, the Spearman correlation coefficient was used, and concordance was estimated with the Kappa coefficient. Results The final sample consisted of 495 participants, of which 52.3% were females. We found a significant correlation coefficient between both tongue (0.26) and masseter (0.33) with ALSTI (P < 0.001). The sarcopenia prevalence confirmed using the alternative muscle measure in MRI was calculated using the ALSTI (tongue = 2.0%, masseter = 2.2%, ALSTI = 2.4%). Concordance between sarcopenia with masseter and tongue versus sarcopenia with ALSTI as reference has a Kappa of 0.989 (P < 0.001) for masseter and a Kappa of 1 for the tongue muscle (P < 0.001). Comorbidities evaluated with the Cumulative Illness Rating Scale were significantly associated with all the muscle measurements: ALSTI (odds ratio [OR] 1.16, 95% confidence interval [CI] 1.07–1.26, P < 0.001), masseter (OR 1.16, 95% CI 1.07–1.26, P < 0.001) and tongue (OR 1.13, 95% CI 1.04–1.22, P = 0.002); the higher the comorbidities, the higher the probability of having abnormal muscle mass. Conclusions ALSTI was significantly correlated with tongue and masseter muscle mass. When performing the sarcopenia diagnostic algorithm, the prevalence of sarcopenia calculated with head muscles did not differ from sarcopenia calculated using DXA, and almost all participants were correctly classified using both methods.publishedVersio
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