Gross nitrification in soils - Contribution of nitrification to N-gas emission from soils

This work contributes to developing a better understanding of nitrification in soils as an important source of N gas emissions from soils. Therefore, the nitrification process as well as N gas produced by nitrification are considered. The work described the common methods and new developed approach for determining the gross nitrification rate. Both measuring and quantifying nitrification in soils have been shown to achieve the objective. One focus is to differentiate the sources of N gases and to quantify the contribution of nitrification to N gas emission from soils. The separation of N gas production into source-related pathways that simultaneously operate in soils requires comprehensive experiments with complex analyses. Therefore a new analytical approach and calculates the fractions of ammonia oxidation, Norg oxidation and denitrification for total soil NO and N2O released from a soil probes at different oxygen states (2.5, 1.2 and 0 % O2) is presented and tested for a five loamy Spanish forest soils. Whereas the relation between ammonia oxidation and denitrification as sources of soil N2O gas release appear to be consistent, which is commonly accepted, the contribution of Norg oxidation was unexpectedly high (up to 76%). Also two model approaches to model the N-gas production in soils are parametrised on experimental data from laboratory studies. The findings are discussed in view of choosing the best approach to predict N2O production during nitrification. and an approach to combine response functions in modelling is presented and tested on field data. The advantage against the conventional combining approaches (multiplicative or min/max approaches) is discussed. N2O production data related to nitrification and nitrification rates were collected and multiple linear regression analysis between the soil properties and N2O product ratios were applied to this dataset to identify functional relationships. Future works to support the development of sufficient model approaches are needed, and in particular, the nitrite and oxygen concentrations in soils are the most important factors for N2O production.Diese Arbeit möchte zu einem besseren Verständnis über den Prozess der Nitrifikation als eine wichtige Quelle der N-Gasemission aus Böden beitragen. Daher werden einleitend die verschiedenen Prozesspfade der Nitrifikation und der Spurengasbildung beschrieben und bildlich dargestellt. Verfahren zur Messung der Nitrifikation und Versuche zu Bestimmung der Umsatzraten werden in der Arbeit vorgestellt. Dabei liegt der Fokus auf der Separation der verschiedenen Quellen von NO und N2O und beschreibt die dafür notwendigen komplexen Versuche inclusive mathematischer Verfahren zu deren Analyse. Mit Hilfe dieser Tools werden die Anteile der Ammoniakoxidation (erster Schritt der autotrophen Nitrifikation), der direkten Oxidation von organischem Stickstoff und der Denitrifikation bei unterschiedlichen Sauerstoffpartialdrücken (2.5, 1.2 und 0 % O2) bestimmt und in einem weiteren Schritt die Methoden auf fünf spanische Waldstandorte angewendet. Interessanterweise sind die Anteile der direkten Oxidation von organischem Stickstoff sehr hoch und auch relativ konstant bei verschiedenen Sauerstoffpartialdrücken. Zwei verschiedene Modellansätze zu Beschreibung der N-Spurengasproduktion in Böden werden vorgestellt und an Labordaten parametrisiert. Die beiden Ansätze und ihre Implikationen für die Bildungswege der N-Spurengasproduktion werden ausgiebig diskutiert. Zusätzlich wird für die Anwendung in Ökosystemmodellen ein auf dem harmonischen Mittel beruhenden Ansatz vorgeschlagen, um verschiedene Responsefunktionen (z.B. die für die Temperatur- und die für die Bodenfeuchteabhängigkeit) miteinander zu verbinden. Im letzten Abschnitt der Arbeit werden die Daten der zuvor beschriebenen Experimente sowie in der Literatur verfügbare Daten zur Bruttonitrifikation und der nitrifikatorischen N2O-Produktion systematisch zusammengetragen, daraus das N2O-Produktion/Nitrifikation-Verhältnis (N2O product ratio) berechnet und dieses mittels multipler lineare Regression gegenüber den Bodeneigenschaften analysiert. Es deutet sich an, dass besonders der aktuelle Sauerstoffpartialdruck und die Nitritkonzentration starken Einfluss auf die N-Spurengasproduktion haben könnten, aber um kausale Zusammenhänge zu bestätigen, gibt es zu wenige insitu Messungen dieser beiden Faktoren in bisherigen Experimenten. Daher endet die Arbeit mit der Aufforderung zukünftig in N-Gasexperimenten immer auch Nitrit und Sauerstoff im Boden zu messen

Resolving structural variability in network models and the brain

Large-scale white matter pathways crisscrossing the cortex create a complex pattern of connectivity that underlies human cognitive function. Generative mechanisms for this architecture have been difficult to identify in part because little is known about mechanistic drivers of structured networks. Here we contrast network properties derived from diffusion spectrum imaging data of the human brain with 13 synthetic network models chosen to probe the roles of physical network embedding and temporal network growth. We characterize both the empirical and synthetic networks using familiar diagnostics presented in statistical form, as scatter plots and distributions, to reveal the full range of variability of each measure across scales in the network. We focus on the degree distribution, degree assortativity, hierarchy, topological Rentian scaling, and topological fractal scaling---in addition to several summary statistics, including the mean clustering coefficient, shortest path length, and network diameter. The models are investigated in a progressive, branching sequence, aimed at capturing different elements thought to be important in the brain, and range from simple random and regular networks, to models that incorporate specific growth rules and constraints. We find that synthetic models that constrain the network nodes to be embedded in anatomical brain regions tend to produce distributions that are similar to those extracted from the brain. We also find that network models hardcoded to display one network property do not in general also display a second, suggesting that multiple neurobiological mechanisms might be at play in the development of human brain network architecture. Together, the network models that we develop and employ provide a potentially useful starting point for the statistical inference of brain network structure from neuroimaging data.Comment: 24 pages, 11 figures, 1 table, supplementary material

The 64 Mpixel wide field imager for the Wendelstein 2m Telescope: Design and Calibration

The Wendelstein Observatory of Ludwig Maximilians University of Munich has recently been upgraded with a modern 2m robotic telescope. One Nasmyth port of the telescope has been equipped with a wide-field corrector which preserves the excellent image quality (< 0.8" median seeing) of the site (Hopp et al. 2008) over a field of view of 0.7 degrees diameter. The available field is imaged by an optical imager (WWFI, the Wendelstein Wide Field Imager) built around a customized 2 $\times$ 2 mosaic of 4k $\times$ 4k 15 \mu m e2v CCDs from Spectral Instruments. This paper provides an overview of the design and the WWFI's performance. We summarize the system mechanics (including a structural analysis), the electronics (and its electromagnetic interference (EMI) protection) and the control software. We discuss in detail detector system parameters, i.e. gain and readout noise, quantum efficiency as well as charge transfer efficiency (CTE) and persistent charges. First on sky tests yield overall good predictability of system throughput based on lab measurements.Comment: 38 pages 19 Figures To be published in Springer Experimental Astronom

Phase II trial of preoperative radiochemotherapy with concurrent bevacizumab, capecitabine and oxaliplatin in patients with locally advanced rectal cancer

Background: Preoperative radiochemotherapy (RCT) with 5-FU or capecitabine is the standard of care for patients with locally advanced rectal cancer (LARC). Preoperative RCT achieves pathological complete response rates (pCR) of 10-15%. We conducted a single arm phase II study to investigate the feasibility and efficacy of addition of bevacizumab and oxaliplatin to preoperative standard RCT with capecitabine. Methods: Eligible patients had LARC (cT3-4; N0/1/2, M0/1) and were treated with preoperative RCT prior to planned surgery. Patients received conventionally fractionated radiotherapy (50.4 Gy in 1.8 Gy fractions) and simultaneous chemotherapy with capecitabine 825 mg/m2 bid (d1-14, d22-35) and oxaliplatin 50 mg/m2 (d1, d8, d22, d29). Bevacizumab 5 mg/kg was added on days 1, 15, and 29. The primary study objective was the pCR rate. Results: 70 patients with LARC (cT3-4; N0/1, M0/1), ECOG < 2, were enrolled at 6 sites from 07/2008 through 02/2010 (median age 61 years [range 39–89], 68% male). At initial diagnosis, 84% of patients had clinical stage T3, 62% of patients had nodal involvement and 83% of patients were M0. Mean tumor distance from anal verge was 5.92 cm (± 3.68). 58 patients received the complete RCT (full dose RT and full dose of all chemotherapy). During preoperative treatment, grade 3 or 4 toxicities were experienced by 6 and 2 patients, respectively: grade 4 diarrhea and nausea in one patient (1.4%), respectively, grade 3 diarrhea in 2 patients (3%), grade 3 obstipation, anal abscess, anaphylactic reaction, leucopenia and neutropenia in one patient (1.4%), respectively. In total, 30 patients (46%) developed postoperative complications of any grade including one gastrointestinal perforation in one patient (2%), wound-healing problems in 7 patients (11%) and bleedings in 2 patients (3%). pCR was observed in 12/69 (17.4%) patients. Pathological downstaging (ypT < cT and ypN ≤ cN) was achieved in 31 of 69 patients (44.9%). All of the 66 operated patients had a R0 resection. 47 patients (68.1%) underwent sphincter preserving surgery. Conclusions: The addition of bevacizumab and oxaliplatin to RCT with capecitabine was well tolerated and did not increase perioperative morbidity or mortality. However, the pCR rate was not improved in comparison to other trials that used capecitabine or capecitabine/oxaliplatin in preoperative radiochemotherapy

Digitalwirtschaft - Ein wichtiger Stützpfeiler in der Krise

DIGITALWIRTSCHAFT - EIN WICHTIGER STÜTZPFEILER IN DER KRISE Digitalwirtschaft - Ein wichtiger Stützpfeiler in der Krise / Pretzell, Claus (CC BY) ( -

Konjunktur ist nicht alles Đ Trends auf dem Berliner Arbeitsmarkt

KONJUNKTUR IST NICHT ALLES Đ TRENDS AUF DEM BERLINER ARBEITSMARKT Konjunktur ist nicht alles Đ Trends auf dem Berliner Arbeitsmarkt / Mertens, Hartmut (Rights reserved) ( -

THREE DIMENSIONAL MEASUREMENT OF THE GEOMETRY OF THE HUMAN MOTION APPARATUS

INTRODUCTION: This work is part of a project of the Department for Sports Medicine to calculate the internal stresses arising when jumping from a squat position. The goal of the project is to facilitate individual calculations by establishing a biomechanical model whose parameters are the major anatomical-geometrical and physiological quantities, gained by electromyogram (EMG) and radiological measurement. Procedures for acquiring the latter data are described here. METHODS: As the study did not involve pathologies, ionizing radiation was ruled out, and magnetic resonance imaging (MRI) was used. The biomechanical model required geometrical parameters from joint positions beyond those occurring during the squat-vault, so the Siemens Magnetom Open device was chosen. It has the disadvantage of relatively low magnetic field strength (0.2 T), but allows for almost unlimited movement in the table plane. Different measurement parameters were evaluated. As the length of the field of view was about 25 cm, the different joints had to be scanned separately. A positioning table was used to serve three purposes: 1. Positioning with defined joint angles, so the morphology could be related to the EMG measurements. 2. Exertion of force, to measure the geometry of muscles and tendons under strain. 3. Placement of markers with high MRI contrast, to relate the relative position of the scans of the different joints. [delete line space]. The evaluation of the images was done using the ‘Tübinger Medstation’ software developed by the Department of Computer Science at the University of Tübingen. RESULTS: Although the use of T2 weighted sequences resulted in better soft tissue contrast, the T1 weighted spin echo sequence was preferred because of shorter acquisition time, which was an important factor because measurements had to be made under strain. Bones and tendons, with their low hydrogen content, produce weak signals in MRI and thus contrast with the adjacent soft tissue. Even shorter acquisition times by use of a gradient sequence were ruled out because of their low signal/noise ratio, which rendered the fascies undetectable. Automatic segmentation of these fascies is extremely hard to achieve. The ‘Medstation’ software was used to extract coordinates of muscle and tendon insertions by hand and combine them in a common frame of reference. CONCLUSIONS: A procedure has been established to extract the geometrical data of muscles, tendons and osseous structures important for the biomechanical model. For this model, extended muscle and tendon insertions have to be reduced to a point by calculation of the center of mass of the insertion area. A table for the positioning of the probationer enabled positioning with reproducible joint angles under exertion of strain. To define the relative position of different scans a screen of markers was integrated into this plate