51 research outputs found
SecA mediated protein translocation in Escherichia coli
No full textThe movement of proteins across or integration of proteins into the cytoplasmic membrane of Escherichia coli is mediated by the multimeric membrane protein complex translocase. The core of the translocase consists of a motor protein, the ATPase SecA, and a protein-conducting channel, formed by the integral membrane proteins SecY and SecE. The SecYE complex is highly conserved, with homologs in the cytoplasmic membrane of Archae, the chloroplast thylakoid membrane, and the eukaryotic endoplasmatic reticulum (ER). SecA is unique for the bacterial post-translational translocation pathway. It is absent both in Archaea and in the eukaryotic ER, but a homolog exists in plant chloroplasts. SecA is an soluble protein that distributes between cytoplasmic and membrane associated states. The interaction with the cytoplasmic membrane occurs via low affinity interactions with anionic phospholipids and by a high affinity interaction with the SecYEG complex. At the membrane SecA forms a receptor for preproteins and drives their stepwise movement through the SecYEG channel [93, 173]. ...
Zie: Summary.
Ja, goed te deunen onze machtige (Psalm 147,1): De zoektocht naar een toonzetting van de Psalmen
No full textThis article describes the quest for a composition of the psalms. Vatican II proclaimed a wish in the constitution about liturgy. The hours of prayer had to be renewed, so that not only clergy and monastics, but also laymen would be able to join. Psalms formed the heart of these hours of prayer. After Vatican II, there was no liturgic translation in Dutch, nor any music, in order to sing it. In 1970, Kees aaijman began putting together prayer celebrations. After roughly 50 years of experimenting, a form of prayer arose in which one psalm is central: the Psalm celebration. By now, the series of 150 Psalm celebrations is nearly completed. For the past ten years, Kees Waaijman and the author have sought a composition of the psalms that does justice to both the individuality of the psalm and the praying people of God. Although initially the psalmic stanza arrangement seemed to be a guidance, this gradually appeared not to work. The music drew too much attention at the expense of praying. It is all about facilitating the saying of the psalm verse, consisting of two half verses that are separated and connected by a meditative caesura. Each half verse numbers an amount of pulse moments, mostly three. The composition must do these pulse moments justice, in order to provide the saying the optimal opportunity, causing the salm to be efficient in the prayer’s head and heart. After a search spanning 50 years, a space opened in which God and man are able to meet
Concept design of a modular heavy lift beam
No full textThe heavy lift market is characterized by ultra heavy and/or odd sized loads. Heavy transports are unique projects, which are engineered for that one time job. Standard heavy lift and transport equipment is used to the extent possible for each project, but often specialized structures are required. A structure that is often used for this purpose is a heavy lift beam. Heavy lift beams are used for load spreading, as well as applications in horizontal and vertical transport. RollDock is a shipping company that provides worldwide heavy lift services over sea. RollDock is currently in the process of designing a new wide deck heavy lift vessel for loads up to 15000 tons, the Module Carrier (MC). This type of vessel will be put into service in 2015. When loading ultra heavy loads, a support structure is required to prevent damage to the deck due to concentrated loads. Current practice is that this support structure is engineered and manufactured individually for each project. To reduce on engineering and material cost, RollDock has requested to design a standardized steel beam that can be re-used for several projects. For increased productivity of this standardized beam, it must be multi functional to be used for other heavy lift purposes than solely as supports on the MC. These purposes are also found in RollDock’s sister company Roll-Lift, which facilitates heavy lift projects on land. The functions of the beam are determined using past RollDock and Roll-Lift projects, as well as functions that may be useful in future projects. The functions for the modular beam are skid support beam, grillage, different parts of a heavy lift gantry, a vertical spacer and a temporary bridge. The goal of this research is to develop a concept design of a modular, containerized, multi functional beam for heavy lift purposes, with the main purpose to be used for loading the BigRoll MC using platform trailers or skidding.Mechanical, Maritime and Materials EngineeringMarine and Transport TechnologyTransport Engineering and Logistics2014.TEL.785
Predicting the impact of sea-level rise in Baie Orientale and Baie de L'Embouchure, Saint Martin: Application of a hydrodynamic model including seagrass and coral reefs
No full textShallow bays in the Caribbean, like Baie Orientale and Baie de L'Embouchure in Saint Martin, are often sheltered by coral reefs and covered by seagrass meadows. They provide valuable services as tourism and coastal protection. The ecosystems are linked through biological, chemical and physical processes. But they are under pressure due to sea-level rise. The response of one of the ecosystems to climate change could impact the other ecosystem. In order to predict the impact of sea-level rise on the biogeomorphology in Baie Orientale and Baie de L'Embouchure, the hydrodynamic model Delft3D Flexible Mesh is applied. The effect of seagrass meadows and coral reefs on both flow and waves are captured with this model. In this way, the long term change in average hydrodynamic conditions due to sea-level rise is determined depending on the response of the ecosystems. A wave-driven circulation is found in both bays with flows of 0.5 m/s over the reefs and currents of 0.2 m/s inside the bays. The hydrodynamic conditions are mainly determined by the reef height. Depending on the response of coral reefs to climate change and the amount of sea-level rise, the wave height inside the bays and the wave-induced currents increase. Under the worst-case scenario, where coral reefs degrade and seagrass meadows die, flow velocities increase by more than 100% in Baie de L'Embouchure and by 200% in Baie Orientale under a sea-level rise of 0.87 m. The significant wave height rises to 300% in Baie Orientale and doubles in Baie de L'Embouchure. But this increase of hydrodynamic stresses is not expected to lead to devastating damage to coral reefs and seagrass meadows. Instead, the response of coral reefs will be determined by changing water temperatures and ocean acidification. A shift in seagrass occurrence due to the changed hydrodynamics is expected. The long term impact of sea-level rise on the biogeomorphology of Baie de L'Embouchure and Baie Orientale seems to be limited. The ability to mitigate the impact of sea-level rise is shown and the resilience of the ecosystems proved, which is very promising for other shallow Caribbean bays that are threatened by sea-level rise. SCENE
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