3,169 research outputs found

    Impact of an electric field on P-type ATPases

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    P-type ATPases are membrane proteins acting as ion pumps that drive an active transport of cations across the membrane against a concentration gradient. The required energy for the ion transport is provided by binding and hydrolysis of ATP. A reaction mechanism of ion transport and energy transduction is assumed to be common for all P-type ATPases and generally described by the Post-Albers cycle. Transient currents and charge translocation of P-type ATPases were extensively investigated by electrical measurements that apply voltage jumps to initiate the reaction cycle. In this study, we simulate an applied voltage across the membrane by an electric field and perform electrostatic calculations in order to verify the experimentally-driven hypothesis that the energy transduction mechanism is regulated by specific structural elements. Side chain conformational and ionization changes induced by the electric field are evaluated for each transmembrane helix and the selectivity in response is qualitatively analyzed for the Ca2+-ATPase as well as for structural models of the Na+/K+-ATPase. Helix M5 responds with more conformer changes as compared to the other transmembrane helices what is even more emphasized when the stalk region is included. Thus our simulations support experimental results and indicate a crucial role for the highly conserved transmembrane helix M5 in the energy transduction mechanism of P-type ATPases

    Living Shorelines: A Novel Remedial Approach for Contaminated Sediments

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    From 1926 to 1986, the former Lordship Gun Club, located on Long Island Sound in Stratford, Connecticut, was operated as a trap and skeet shooting facility, which resulted in the discharge of lead shot into surrounding waters and sediments. Between 1987 and 2000, studies were conducted to inform remedial decision-making; remediation occurred in several phases from 2000 to 2011. Remedial action involved excavation of shot-containing sediments and associated vegetation from the intertidal zone, lead shot extraction from excavated sediments, and replacement of sediments to their native locations. Subsequent monitoring has revealed that this action destabilized intertidal sediments and led to substantial erosion of the shoreline and dunes, which has limited efforts to reestablish native wetland vegetation. Erosion of sediment from the intertidal zone has also resulted in the concentration of residual lead shot on the sediment surface, which poses a potential exposure hazard to migratory waterfowl. To address these issues, a living shoreline pilot project, which includes an artificial reef and a smooth cordgrass (Spartina alterniflora) marsh, was constructed in May 2014. The purpose of the pilot project was to evaluate living shorelines for their potential: (1) decrease shoreline and dune erosion at the site; (2) further reduce potential ecological exposure to residual lead shot; and, (3) restore wildlife habitat within the adjacent Housatonic River Estuary and Long Island Sound. Results were evaluated in the context of a Before-After-Control-Impact (BACI) statistical framework. Methods, preliminary data, and lessons-learned are shared

    Reflecting on the role of universities in the fight against corruption

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    Purpose – Corruption continues to ravage societies around the world. The fight against corruption can be fruitful only if approached from multiple standpoints. Thus, corruption must also be approached from an academic and educational perspective. The purpose of this paper is to provide a good practice example of how universities and business schools can take actions to align themselves with the international sustainability and anticorruption agenda. Design/methodology/approach – The six principles of the United Nations Principles for Responsible Management Education (PRME) provide a framework for higher education institutions to address corruptionrelated issues. This paper presents the case story of the Swiss-based University of Applied Sciences HTW Chur, which developed an academic working agenda on corruption-related topics based on the principles of the PRME. Findings – The case story shares the actions that HTW Chur has taken and the benefits that have resulted from the university’s work. The findings show that to address corruption-related issues, scholars from the university took actions related to four principles in the PRME: method, research, partnership and dialogue. Furthermore, the results indicate that in addition to the university itself, public and private institutions have also profited from the actions taken. Research limitations/implications – This paper is founded on a single case story; thus, the usual limitations of this research design apply. Practical implications – It becomes apparent that the needs of the private sector in the fight against corruption could be addressed by engaging in and strengthening partnerships with universities. Thus, it seems beneficial to develop guidelines and standards to facilitate collaborations and dialogue in a participatory and transparent way. Originality/value – The paper provides a good practice example of how universities can take actions to align themselves with the international sustainability and anticorruption agenda

    kClust: fast and sensitive clustering of large protein sequence databases

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    Background: Fueled by rapid progress in high-throughput sequencing, the size of public sequence databases doubles every two years. Searching the ever larger and more redundant databases is getting increasingly inefficient. Clustering can help to organize sequences into homologous and functionally similar groups and can improve the speed, sensitivity, and readability of homology searches. However, because the clustering time is quadratic in the number of sequences, standard sequence search methods are becoming impracticable. Results: Here we present a method to cluster large protein sequence databases such as UniProt within days down to 20\%-30\% maximum pairwise sequence identity. kClust owes its speed and sensitivity to an alignment-free prefilter that calculates the cumulative score of all similar 6-mers between pairs of sequences, and to a dynamic programming algorithm that operates on pairs of similar 4-mers. To increase sensitivity further, kClust can run in profile-sequence comparison mode, with profiles computed from the clusters of a previous kClust iteration. kClust is two to three orders of magnitude faster than clustering based on NCBI BLAST, and on multidomain sequences of 20\%-30\% maximum pairwise sequence identity it achieves comparable sensitivity and a lower false discovery rate. It also compares favorably to CD-HIT and UCLUST in terms of false discovery rate, sensitivity, and speed. Conclusions: kClust fills the need for a fast, sensitive, and accurate tool to cluster large protein sequence databases to below 30\% sequence identity. kClust is freely available under GPL at ftp://toolkit.lmb.uni-muenchen.de/pub/kClust/

    Die Bedeutung der außenwirtschaftlichen AktivitĂ€ten fĂŒr den deutschen Mittelstand: Untersuchung im Auftrag des Bundesministeriums fĂŒr Wirtschaft und Technologie

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    Das Institut fĂŒr Mittelstandsforschung (IfM) Bonn hat in Kooperation mit dem Volkswirtschaftlichen Institut fĂŒr Mittelstand und Handwerk an der UniversitĂ€t Göttingen (ifh) im Auftrag des Bundesministeriums fĂŒr Wirtschaft und Technologie (BMWi) eine Studie zu den AuslandsaktivitĂ€ten mittelstĂ€ndischer Unternehmen durchgefĂŒhrt. Ziel der Studie war es, den Anteil der mittelstĂ€ndischen Unternehmen am deutschen Export und Import von GĂŒtern und Dienstleistungen und dessen Entwicklung in den letzten fĂŒnf Jahren getrennt nach Branchen, Regionen und UnternehmensgrĂ¶ĂŸe zu ermitteln. Zudem sollte die Auswirkung auf die BeschĂ€ftigung dargestellt und der Anteil der deutschen Wertschöpfung der exportorientierten mittelstĂ€ndischen Unternehmen bestimmt werden. An der Befragung beteiligten sich mehr als 500 mittelstĂ€ndische Unternehmen. ZusĂ€tzlich wurden 94 Expertenmeinungen eingeholt. --
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