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Search Results: 1 - 10 of 332611 matches for " S. Hans "
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Towards universal systems for recombinant gene expression
Hans S?rensen
Microbial Cell Factories , 2010, DOI: 10.1186/1475-2859-9-27
Abstract: Escherichia coli was the first host to be used for recombinant gene expression almost 40 years ago [1]. Within the past 15 years, Pichia pastoris has successfully entered the scene and is now the second most-used host for recombinant gene expression. Based on searches of the PubMed citation database, the use of P. pastoris as an expression host has increased from 4% to 17% of the total recombinant genes reported on from 1995 to 2009 (Fig. 1). Within the same time period, the usage of E. coli as an expression host remained constant, with approximately 60% of the recombinant genes reported on in journals indexed in PubMed being expressed in E. coli. Similar trends prevailed when analyzing publications in the journal Microbial Cell Factories during the period from 2005 to 2009 (Fig. 1). Several other expression systems are widely used, but to a lesser extent than E. coli and P. pastoris. So, why are E. coli and P. pastoris particularly suited for recombinant gene expression?Protein produced from a recombinant gene in E. coli as a soluble and functional product with high yield is the ideal situation for most research and industrial protein production purposes [2-4]. However, this situation is far from realistic for all recombinant gene products. In particular, proteins derived from eukaryotes are prone to inclusion body formation and low yields. This outcome can be explained by the fact that the rate of gene translation in E. coli is 4- to 10-fold higher than in eukaryotes [5]. Correct formation of disulfide bonds, protein folding, and protein function must be carefully assessed both when the proteins have been recombinantly produced in E. coli in a soluble form, when they have been refolded in vitro, or obtained from any other source [6]. Further, E. coli should not be used as the expression system if posttranslational modifications (PTMs) are of importance for the study or purpose of the protein because these microbes are unable to incorporate PTMs, including N-linked
Analysis of Motion in Single-Point Mooring Systems
Hans R. S?rheim
Modeling, Identification and Control , 1980, DOI: 10.4173/mic.1980.3.2
Abstract: A mathematical model of the slow motions of ships in single-point moorings is described. The model is used for analysis of stability of equilibrium positions. An analytical criterion for stability relating main system parameters is derived under simplifying assumptions. A numerical example with a 100 000 dwt tanker showed that the effect of wind and current are of equal importance with respect to system stability, and astern propulsion is generally required to avoid stable oscillations. Stability problems in waves have not been found. The effects of time varying excitations are discussed and illustrated by simulation.
The work environment, critical incidents, debriefing and psychological functioning—a study of trade union members in Sweden
Hans Peter S?ndergaard
SJWEH Supplements , 2008,
Abstract: OBJECTIVES: This study explored the associations between critical incidents, the psychosocial work environment, debriefing, and poor psychological health, including posttraumatic stress disorder (PTSD), among shop attendants. METHODS: Questionnaires were administered to members of the Swedish trade union and to persons who had had brief treatment after a robbery. RESULTS: Of the respondents, 6.6% reported robbery in their workplace. Those who were repeatedly exposed to robberies and scored above the cut-off for PTSD comprised 14.2–16.4% of the total number of PTSD cases. The workers exposed to a robbery felt less safe at work, without differing from others regarding other measures of psychosocial factors, namely, social support, influence, and job strain. The participants with PTSD reported significantly worse social support at work, but did not differ as to influence or demand–control. Debriefing (yes, no) had no statistical relationship with the prevalence of PTSD among robbery victims, but, in the whole group, including other traumatic events, debriefing showed a weak, albeit significant association with self-rated psychological function. The debriefed (after any negative work- or nonwork-related event) participants did not differ as regards symptoms of PTSD, but they reported less depression and better psychological functioning, even after adjustment for social support at work. A long sick leave after a robbery was associated with poor support from managers and colleagues. CONCLUSIONS: Social support, including support from managers, was associated with few symptoms, good psychological function, and shorter sick leave. People with PTSD have poorer general work conditions and social support, but similar influence or demand–control at work.
Open access publishing: a girder in the success of the Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine
Hans Lossius, Kjetil S?reide
Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine , 2011, DOI: 10.1186/1757-7241-19-7
Abstract: SJTREM converted into open access (OA) online publishing in July 2008 [2]. The decision was based on the importance of making research accessible for all, regardless of financial status or capabilities. This conversion resulted in a substantial rise in submissions, and not least citations. In line with the visions of saving more lives, the Norwegian Air Ambulance Foundation and the Laerdal Foundation for Acute Medicine have supported SJTREM by covering the article processing charges for the first and critical 2 years of establishing an independent scientific, open access journal of trauma, resuscitation and emergency medicine [3-5].The OA conversion was timely. Scandinavian research founders have for the last two years been steadily moving from a supportive attitude for the OA principles, to making policy decisions that have a direct guidance to authors to publish OA. The Norwegian Research Council declared in 2009 that all public founded research should be published OA [6], and in Denmark the Open Access Committee has, on behalf of the Ministry of Science, Technology and Innovation, made clear recommendations for OA publishing [7]. But the most significant step till now was the decision of the Swedish Research Council and other major Swedish research founders to include an OA mandate for all its research grants from 2010 [8-10]. In line with this, universities in Scandinavia are moving towards OA publishing, and national libraries are following closely. Chalmers University of Technology was in 2010 the first Swedish university to take a strong Open Access mandate [11], and there is probably just a question of time before this is the common policy within most Scandinavian Universities.The Scandinavian move is part of the wider global picture where mandates and funding mechanisms, constituting the equivalent of library budgets at many universities, are springing into life. With the support of European Commission, OA are evolving all over Europe http://www.openaire.eu
Soluble expression of recombinant proteins in the cytoplasm of Escherichia coli
Hans S?rensen, Kim Mortensen
Microbial Cell Factories , 2005, DOI: 10.1186/1475-2859-4-1
Abstract: Microorganisms like the enterobacterium Escherichia coli are outstanding factories for recombinant expression of proteins. An expression system for the production of recombinant proteins in E. coli usually involves a combination of a plasmid and a strain of E. coli [1]. The main purpose of recombinant protein expression is often to obtain a high degree of accumulation of soluble product in the bacterial cell. This strategy is not always accepted by the metabolic system of the host and in some situations a cellular stress response is encountered. Another response encountered in recombinant systems is the accumulation of target proteins into insoluble aggregates known as inclusion bodies. These aggregated proteins are in general misfolded and thus biologically inactive [2].Under normal cellular conditions a subset of cytoplasmic proteins are able to fold spontaneously [3] while aggregation prone proteins require the existence of a number of molecular chaperones that interact reversibly with nascent polypeptide chains to prevent aggregation during the folding process [4]. Aggregation of recombinant proteins overexpressed in bacterial cells could therefore result either from accumulation of high concentrations of folding intermediates or from inefficient processing by molecular chaperones. No universal approach has been established for the efficient folding of aggregation prone recombinant proteins [1].The literature describes a number of methods for the redirection of proteins from inclusion bodies into the soluble cytoplasmic fraction (Figure 1). Overall they can be divided into procedures where protein is refolded from inclusion bodies [5] and procedures where the expression strategy is modified to obtain soluble expression. In this review we focus on methods developed for soluble expression in the E. coli cytoplasm. Refolding from inclusion bodies is in many cases considered undesireable, but is however sometimes the method of choice. The major obstacles are the poo
A year of contemplation: looking back and moving forward
Kjetil S?reide, Hans Lossius
Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine , 2009, DOI: 10.1186/1757-7241-17-31
Abstract: The Journal has over the past year received and published original and review papers from several Scandinavian research groups [3-11]. Also, contributions from several international researchers including the USA [12-15], several European countries (e.g. UK, Germany, Switzerland, Italy and Greece) [16-22], and even Asia [23] are influencing the Journal content. Currently, we have submissions in-house from virtually all corners of the world, with several contributors outside Scandinavia and Europe. We believe this demonstrates the increasing global impact of the Journal and hope to establish a truly international profile and outreach while not loosing the vision of being a forum for scientific exchange and improvements for Scandinavian countries in particular. Also, the Journal has supported and published abstracts from international congresses, with the supplements from the London Trauma Conference available on the website[24], and the abstracts for the 3rd Scandinavian Update on Trauma, Resuscitation and Emergency Medicine and the Research Symposium 2009 for the Danish Society of Emergency Medicine will follow soon.The success of the Journal is measured also by the number of accessed papers – currently, more than 10 of the published papers have been accessed over 1000 times, even though many of them have been available for only a few months on the Web, and 3 papers have been accessed more than 2000 times each[13,25,26]. The international consensus paper by Ringdal et al[26] has even been included in the "Faculty of 1000 medicine" with almost 5000 hits in less than one year.We strive to ensure high visibility of the Journal, and have for 2008 published a yearbook, which has been distributed to several hundred participants at the Scandinavian Update conference as well as to a wide number of libraries and research institutions. The success of this publication will be repeated for 2009, thus ensuring high visibility both electronically as well as on paper.Several of the
Definite Integrals using Orthogonality and Integral Transforms
Howard S. Cohl,Hans Volkmer
Symmetry, Integrability and Geometry : Methods and Applications , 2012,
Abstract: We obtain definite integrals for products of associated Legendre functions with Bessel functions, associated Legendre functions, and Chebyshev polynomials of the first kind using orthogonality and integral transforms.
Forage diversity and nutrition supply of reindeer
Hans Staaland,Stein S?b?
Rangifer , 1993,
Abstract: This study describes the mineral and nitrogen concentrations of reindeer forage plants from the Elg reindeer herding district of south-eastern Norway. The data are compared with results from 5 other areas in Norway. Emphasis is put on the importance of environmental diversity. Different plant species accumulate Ca, Mg, P, S, Na, K, CI and K to a varying degree but reindeer can meet their nutritional requirements by eating different types of forage. Examples are sodium from aquatic herbs, sulphur and sodium from horsetails etc. Of further importance are variations in soil type, phenological development of plants in relation to differences in time for snowmelting, as well as different levels of nutrients in forage from different geographical.
Seasonal variations in mineral status of reindeer calves from Elgaa reindeer herding district, Norway
Hans Staaland,Stein S?b?
Rangifer , 1987,
Abstract: Botanical analyses of rumen content from reindeer calves slaughtered during the period August to April showed dominance of grasses (36%), lichens (30%) and woody plants (21 %). Na content in rumen, bone, liver and muscle samples increased from August to April, whereas K and Mg decreased. It is suggested that the high level of K in summer forage'increases Na excretion and drains the body reserves of this mineral. The body reserves of Na are apparently rebuilt through fall and winter. Sesongvariasjoner i mineralstatus hos reinkalver fra Elg reinbeitedistrikt. Abstract in Norwegian / Sammendrag: Botaniske analyser av vominnhold fra reinkalver som ble avlivet i perioden august til april viste dominans av gress (36%), lav (30%) og treaktige planter (21%). Innholdet av Na i vom, bein, lever og muskelpr ver kte fra august til april, mens K og Mg avtok. Det blir antydet at det h ye niv et av K i sommerbeite ker ekskresjon av Na og minsker kroppsbeholdningen av dette mineralet. Kroppsreservene av Na synes bli bygget opp igjen i l pet av h st og vinter.
Definite Integrals using Orthogonality and Integral Transforms
Howard S. Cohl,Hans Volkmer
Mathematics , 2012, DOI: 10.3842/SIGMA.2012.077
Abstract: We obtain definite integrals for products of associated Legendre functions with Bessel functions, associated Legendre functions, and Chebyshev polynomials of the first kind using orthogonality and integral transforms.
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