Topological tunneling with Dynamical overlap fermions

Tunneling between different topological sectors with dynamical chiral fermions is difficult because of a poor mass scaling of the pseudo-fermion estimate of the determinant. For small fermion masses it is virtually impossible using standard methods. However, by projecting out the small Wilson eigenvectors from the overlap operator, and treating the correction determinant exactly, we can significantly increase the rate of topological sector tunneling and reduce substantially the auto-correlation time. We present and compare a number of different approaches, and advocate a method which allows topological tunneling even at low mass with little addition to the computational cost.Comment: 17 pages; v2 as accepted in computer Physics Communication

Extracting the Single-Particle Gap in Carbon Nanotubes with Lattice Quantum Monte Carlo

We show how lattice Quantum Monte Carlo simulations can be used to calculate electronic properties of carbon nanotubes in the presence of strong electron-electron correlations. We employ the path integral formalism and use methods developed within the lattice QCD community for our numerical work and compare our results to empirical data of the Anti-Ferromagnetic Mott Insulating gap in large diameter tubes.Comment: 8 pages, 5 figures, Lat2017 proceedin

Numerical Methods for the QCD Overlap Operator:III. Nested Iterations

The numerical and computational aspects of chiral fermions in lattice quantum chromodynamics are extremely demanding. In the overlap framework, the computation of the fermion propagator leads to a nested iteration where the matrix vector multiplications in each step of an outer iteration have to be accomplished by an inner iteration; the latter approximates the product of the sign function of the hermitian Wilson fermion matrix with a vector. In this paper we investigate aspects of this nested paradigm. We examine several Krylov subspace methods to be used as an outer iteration for both propagator computations and the Hybrid Monte-Carlo scheme. We establish criteria on the accuracy of the inner iteration which allow to preserve an a priori given precision for the overall computation. It will turn out that the accuracy of the sign function can be relaxed as the outer iteration proceeds. Furthermore, we consider preconditioning strategies, where the preconditioner is built upon an inaccurate approximation to the sign function. Relaxation combined with preconditioning allows for considerable savings in computational efforts up to a factor of 4 as our numerical experiments illustrate. We also discuss the possibility of projecting the squared overlap operator into one chiral sector.Comment: 33 Pages; citations adde

Effect of COVID on Postpartum Depression (PPD)

Purpose: To determine if the rates of postpartum depression have changed during COVID To identify differences in characteristics of women with postpartum depression during COVI

cGMP at the centre of attention: emerging strategies for activating the cardioprotective PKG pathway.

The nitric oxide (NO)-protein kinase G (PKG) pathway has been known for some time to be an important target for cardioprotection against ischaemia/reperfusion injury and heart failure. While many approaches for reducing infarct size in patients have failed in the past, the advent of novel drugs that modulate cGMP and its downstream targets shows very promising results in recent preclinical and clinical studies. Here, we review main aspects of the NO-PKG pathway in light of recent drug development and summarise potential cardioprotective strategies in which cGMP is the main player

Reactors for microbial electrobiotechnology

From the first electromicrobial experiment to a sophisticated microbial electrochemical process - it all takes place in a reactor. Whereas the reactor design and materials used strongly influence the obtained results, there are no common platforms for MES reactors. This is a critical convention gap, as cross-comparison and benchmarking among MES as well as MES vs. conventional biotechnological processes is needed. Only knowledge driven engineering of MES reactors will pave the way to application and commercialization. In this chapter we first assess the requirements on reactors to be used for bioelectrochemical systems as well as potential losses caused by the reactor design. Subsequently, we compile the main types and designs of reactors used for MES so far, starting from simple H-cells to stirred tank reactors. We conclude with a discussion on the weaknesses and strengths of the existing types of reactors for bioelectrochemical systems that are scored on design criteria and draw conclusions for the future engineering of MES reactors. [GRAPHICS]

Pathophysiological Mechanisms in Sclerosing Skin Diseases

Sclerosing skin diseases represent a large number of distinct disease entities, which include systemic sclerosis, localized scleroderma, and scleredema adultorum. These pathologies have a common clinical appearance and share histological features. However, the specific interplay between cytokines and growth factors, which activate different mesenchymal cell populations and production of different extracellular matrix components, determines the biomechanical properties of the skin and the clinical features of each disease. A better understanding of the mechanisms underlying these events is prerequisite for developing novel targeted therapeutic approaches

Design und Charakterisierung von Reaktorkonzepten für Mikrobielle Elektrochemische Technologien

One of the existing challenges for implementing bioelectrochemical systems (BES) in a new bioeconomy is shifting the technology towards industrial use and engineering reactor systems at adequate scales. The goal of this study was to establish and define a rational knowledge-based process design for bioelectrochemical systems. Process development should start with the selection and engineering of the catalysts (electroactive microorganisms or enzymes), followed by first synthesis and optimizations in lab-scale reactors. Modeling and simulation is important to elucidate interactions between the electrochemical and biological component and to support the process design. The last stage is the scale-up of the BES into pilot plant applications and an economic evaluation. The most important open questions of different BES were identified at the start of this work to gain more insight into relevant parameters. A flat-plate microbial fuel cell was designed and the influence of two different inlet setups on performance was investigated. Perpendicular flow through the anode increased the performance 1.8 fold vs. parallel flow. Finite element method simulation revealed that substrate distribution is influenced by the change of inlet setup and is responsible for the improved experimental performance. In recent years, assemblies to host electrodes in bioreactors have been developed. The resulting electrobioreactors also possess the advantages of bioreactors like good scalability and comparability during production processes. Two assemblies enabling a separated and non?separated electrochemical operation, respectively, were designed and extensively characterized. Electrochemical losses over the electrolyte and the membrane were comparable to H?cells, the bioelectrochemical standard reaction system. Current production by the electroactive model organism Shewanella oneidensis was improved by the separation of anodic and cathodic chamber by a Nafion membrane. To date, the products of microbial electrosyntheses are rather limited to simple chemical structures. In this work the electroactive microorganism Cupriavidus necator was genetically engineered and used in BES for production of the terpene humulene from CO2 and electricity. This work serves as proof of concept that also more complex and valuable compounds can be produced in BES. Electrobiotechnology is a wide spread field. This work shows the development potential and offers solutions for the selected process steps.Eine der bestehenden Herausforderungen für die Umsetzung von bioelektrochemischen Systemen (BES) in einer neuen Bioökonomie ist die Entwicklung von Reaktorsystemen in geeigneten Skalen. Ziel dieser Studie war es, ein rationales, wissensbasiertes Prozessdesign für bioelektrochemische Systeme zu etablieren und zu definieren. Die Prozessentwicklung sollte mit der Auswahl und/oder dem Engineering der Biokatalysatoren beginnen, gefolgt von Synthesen und Optimierung in Laborreaktoren die durch Modellierung und Simulation unterstützt werden. Die letzte Stufe ist das Hochskalieren des BES in Pilotanlagen und eine wirtschaftliche Bewertung. Zu Beginn dieser Arbeit wurden die wichtigsten offenen Fragen verschiedener BES identifiziert, um einen besseren Einblick in die relevanten Parameter zu erhalten. Es wurde eine mikrobielle Flachplatten-Brennstoffzelle entwickelt und der Einfluss von zwei verschiedenen Einlasskonfigurationen auf die Leistung untersucht. Ein direkter Durchfluss durch die Anode erhöhte die Leistung um das 1,8-fache gegenüber einer parallel angeströmten Anode. Die Simulation der Strömung ergab, dass die Substratverteilung durch die Änderung der Einlasskonfiguration beeinflusst wird und für die verbesserte Leistung in den durchgeführten Experimenten verantwortlich war. Zuletzt wurden Halterungen zur Integration von Elektroden in Bioreaktoren entwickelt. Die daraus resultierenden Elektrobioreaktoren besitzen die Vorteile von Bioreaktoren wie gute Skalierbarkeit und Vergleichbarkeit. Zwei Konfigurationen, die einen getrennten bzw. nicht getrennten Betrieb ermöglichen, wurden konzipiert und charakterisiert. Elektrochemische Verluste über den Elektrolyten und der Membran waren vergleichbar mit H-Zellen, dem bioelektrochemischen Standardreaktionssystem. Die Stromproduktion von Shewanella oneidensis wurde durch die Trennung von anodischer und kathodischer Kammer durch eine Nafion-Membran stabilisiert. Bisher sind die Produkte der mikrobiellen Elektrosynthese meist auf einfache chemische Strukturen beschränkt. In dieser Arbeit wurde Cupriavidus necator genetisch verändert und im BES zur Herstellung des Terpens Humulen aus CO2 und Strom eingesetzt. Diese Arbeit dient als Nachweis dafür, dass auch komplexere und wertvollere Verbindungen im BES hergestellt werden können. Die Elektrobiotechnologie ist ein weites Feld. Diese Arbeit zeigt das Entwicklungspotenzial auf und bietet Lösungen für die ausgewählten Prozessschritte

Real-Time Detection of Polymerase Activity Using Supercritical Angle Fluorescence

We investigated the incorporation efficiencies of different fluorescently labelled dNTPs with polymerases by complementary strand synthesis. For this reason single stranded DNA was immobilized on a coverslip and the increase of fluorescence due to the synthesis of the corresponding strand with tagged dNTPs was detected with a supercritical angle fluorescence biosensor in real-time. By comparison of the observed signal intensities it was possible to conclude that the system Cy5-dCTP—Klenow (exonuclease free) fragment gives the best incorporation yield of the investigated enzymes and dNTP