Martin Luther University of Halle-Wittenberg

About: Martin Luther University of Halle-Wittenberg is a education organization based out in Halle, Germany. It is known for research contribution in the topics: Population & Liquid crystal. The organization has 20232 authors who have published 38773 publications receiving 965004 citations. The organization is also known as: MLU & University of Wittenberg.

European Vegetation Archive (EVA): an integrated database of European vegetation plots

Abstract: The European Vegetation Archive (EVA) is a centralized database of European vegetation plots developed by the IAVS Working Group European Vegetation Survey. It has been in development since 2012 and first made available for use in research projects in 2014. It stores copies of national and regional vegetation- plot databases on a single software platform. Data storage in EVA does not affect on-going independent development of the contributing databases, which remain the property of the data contributors. EVA uses a prototype of the database management software TURBOVEG 3 developed for joint management of multiple databases that use different species lists. This is facilitated by the SynBioSys Taxon Database, a system of taxon names and concepts used in the individual European databases and their corresponding names on a unified list of European flora. TURBOVEG 3 also includes procedures for handling data requests, selections and provisions according to the approved EVA Data Property and Governance Rules. By 30 June 2015, 61 databases from all European regions have joined EVA, contributing in total 1 027 376 vegetation plots, 82% of them with geographic coordinates, from 57 countries. EVA provides a unique data source for large-scale analyses of European vegetation diversity both for fundamental research and nature conservation applications. Updated information on EVA is available online at http://euroveg.org/eva-database.

Ex-527 inhibits Sirtuins by exploiting their unique NAD+-dependent deacetylation mechanism

Abstract: Sirtuins are protein deacetylases regulating metabolism and stress responses. The seven human Sirtuins (Sirt1–7) are attractive drug targets, but Sirtuin inhibition mechanisms are mostly unidentified. We report the molecular mechanism of Sirtuin inhibition by 6-chloro-2,3,4,9-tetrahydro-1H-carbazole-1-carboxamide (Ex-527). Inhibitor binding to potently inhibited Sirt1 and Thermotoga maritima Sir2 and to moderately inhibited Sirt3 requires NAD+, alone or together with acetylpeptide. Crystal structures of several Sirtuin inhibitor complexes show that Ex-527 occupies the nicotinamide site and a neighboring pocket and contacts the ribose of NAD+ or of the coproduct 2’-O-acetyl-ADP ribose. Complex structures with native alkylimidate and thio-analog support its catalytic relevance and show, together with biochemical assays, that only the coproduct complex is relevant for inhibition by Ex-527, which stabilizes the closed enzyme conformation preventing product release. Ex-527 inhibition thus exploits Sirtuin catalysis, and kinetic isoform differences explain its selectivity. Our results provide insights in Sirtuin catalysis and inhibition with important implications for drug development.

Biomarker-Based Risk Stratification for Previously Untreated Medullary Thyroid Cancer

Abstract: Context: Preoperative neck ultrasonography may yield false-negative findings in more than one-third of medullary thyroid cancer (MTC) patients. If not cleared promptly, cervical lymph node metastases may emerge subsequently. Reoperations entail an excess risk of surgical morbidity and may be avoidable. Objective: This comprehensive investigation aimed to evaluate in a head-to-head comparison the clinical utility of pretherapeutic biomarker serum levels (basal calcitonin; stimulated calcitonin; carcinoembryonic antigen) for indicating extent of disease and providing biochemical stratification of pretherapeutic MTC risk. Design: This was a retrospective analysis. Setting: The setting was a tertiary referral center. Patients: Included were 300 consecutive patients with previously untreated MTC. Interventions: The intervention was compartment-oriented surgery. Main Outcome Measure: Stratified biomarker levels were correlated with histopathologic extent of disease. Results: Higher biomarker levels reflected la...

Measurement of the Bending Strength of Vapor-Liquid-Solid Grown Silicon Nanowires

Abstract: The fracture strength of silicon nanowires grown on a [111] silicon substrate by the vapor-liquid-solid process was measured. The nanowires, with diameters between 100 and 200 nm and a typical length of 2 Im, were subjected to bending tests using an atomic force microscopy setup inside a scanning electron microscope. The average strength calculated from the maximum nanowire deflection before fracture was around 12 GPa, which is 6% of the Young’s modulus of silicon along the nanowire direction. This value is close to the theoretical fracture strength, which indicates that surface or volume defects, if present, play only a minor role in fracture initiation. Nanowires (NWs) are of interdisciplinary interest to applications in the fields of biomedical sensing, nano- and optoelectronics and photovoltaics due to their electrical, optical, mechanical, and geometrical properties that may deviate substantially from bulk. 1 To name some particularly exciting applications, the reader is referred to the following list: (i) high-frequency electromechanical resonators, 2 (ii) high-aspect ratio tips for surface probe microscopy, 3 (iii) sensor array for electrical detection of cancer markers, 4 (iv) Si NW arrays for photovoltaics, 5 and (v) nanoscale light-emitting diodes. 6 For all these applications the mechanical stability of the NWs is essential for their atomic scale manipulation, functionalization, or integration into device schemes. Several methods were used in the past to access the mechanical properties of silicon NWs and nanobeams. An atomic force microscope (AFM) was used for bending tests of single crystal, micromachined silicon beams (from 1 mm down to 200 nm in width, beam axis oriented in [110] direction). No change in Young’s modulus, but an increase in bending strength by a factor of up to 38 was observed from the millimeter down to the nanometer scale. 7 AFM measurements were also done on silicon NWs (from 10 to 100 nm in diameter, grown along the [111] direction) where a bending modulus of 186 GPa (188 GPa in bulk) was measured. 8

Projecting the continental accumulation of alien species through to 2050

Abstract: Biological invasions have steadily increased over recent centuries. However, we still lack a clear expectation about future trends in alien species numbers. In particular, we do not know whether alien species will continue to accumulate in regional floras and faunas, or whether the pace of accumulation will decrease due to the depletion of native source pools. Here, we apply a new model to simulate future numbers of alien species based on estimated sizes of source pools and dynamics of historical invasions, assuming a continuation of processes in the future as observed in the past (a business-as-usual scenario). We first validated performance of different model versions by conducting a back-casting approach, therefore fitting the model to alien species numbers until 1950 and validating predictions on trends from 1950 to 2005. In a second step, we selected the best performing model that provided the most robust predictions to project trajectories of alien species numbers until 2050. Altogether, this resulted in 3,790 stochastic simulation runs for 38 taxon-continent combinations. We provide the first quantitative projections of future trajectories of alien species numbers for seven major taxonomic groups in eight continents, accounting for variation in sampling intensity and uncertainty in projections. Overall, established alien species numbers per continent were predicted to increase from 2005 to 2050 by 36%. Particularly, strong increases were projected for Europe in absolute (+2,543 ± 237 alien species) and relative terms, followed by Temperate Asia (+1,597 ± 197), Northern America (1,484 ± 74) and Southern America (1,391 ± 258). Among individual taxonomic groups, especially strong increases were projected for invertebrates globally. Declining (but still positive) rates were projected only for Australasia. Our projections provide a first baseline for the assessment of future developments of biological invasions, which will help to inform policies to contain the spread of alien species.