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Search Results: 1 - 10 of 5693 matches for " Geisler Markus "
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Expression of a prokaryotic P-type ATPase in E. coli Plasma Membranes and Purification by Ni2+-affinity chromatography
Geisler Markus
Biological Procedures Online , 1998, DOI: 10.1251/bpo9
Abstract: In order to characterize the P-type ATPase from Synechocystis 6803 [Geisler (1993) et al. J. Mol. Biol. 234, 1284] and to facilitate its purification, we expressed an N-terminal 6xHis-tagged version of the ATPase in an ATPase deficient E. coli strain. The expressed ATPase was immunodetected as a dominant band of about 97 kDa localized to the E. coli plasma membranes representing about 20-25% of the membrane protein. The purification of the Synecho-cystis 6xHis-ATPase by single-step Ni-affinity chromatography under native and denaturating conditions is described. ATPase activity and the formation of phosphointermediates verify the full function of the enzyme: the ATPase is inhibited by vanadate (IC50= 119 &mgr;M) and the formation of phosphorylated enzyme intermediates shown by acidic PAGE depends on calcium, indicating that the Synechocystis P-ATPase functions as a calcium pump.
Phase stability of chromium based compensated ferrimagnets with inverse Heusler structure
Markus Meinert,Manuel Geisler
Physics , 2013, DOI: 10.1016/j.jmmm.2013.04.025
Abstract: Chromium based inverse Heusler compounds of the type Cr2YZ (Y=Co, Fe; Z=Al, Ga, In, Si, Ge, Sn) have been proposed as fully compensated half-metallic ferrimagnets. Such materials are of large interest for spintronics because they combine small magnetic moment with high spin polarization over a wide temperature range. We assess their thermodynamic stability by their formation enthalpies obtained from density functional theory calculations. All compounds under investigation are unstable. Cr2FeSi and Cr2CoAl are stable with respect to the elemental constituents, but decompose into binary phases. Cr2FeGe, Cr2CoGa, Cr2FeSn and Cr2CoIn are found to be unstable with respect to their elemental constituents. We identify possible binary decompositions.
Multiple phases in sputtered Cr2CoGa films
Manuel P. Geisler,Markus Meinert,Jan Schmalhorst,Günter Reiss,Elke Arenholz
Physics , 2013, DOI: 10.1016/j.jallcom.2014.02.035
Abstract: By magnetron co-sputtering, thin films of a nominal Cr2CoGa compound were deposited on MgO and MgAl2O4. To achieve crystallisation in the inverse Heusler structure, different heat treatments were tested. Instead of the inverse Heusler structure, we observed phase separation and precipitate formation in dependence on the heat treatment. The main precipitate is Cr3Ga in A15 structure. The remainder forms Co-rich CoGa in the B2 structure and possibly Cr-rich CoCr in the sigma-phase.
Revisitando o conceito de cidadania: notas para uma educa??o politécnica
Geisler, Adriana;
Trabalho, Educa??o e Saúde , 2006, DOI: 10.1590/S1981-77462006000200008
Abstract: in opposition to a community and school project which have been denying the effective citizenship to a great contingent of youth and brazilian workers, the polytechnic conception emerges as a part of an emancipating project which is far from the liberal ideology and from its reflexes on the education and work fields. retaking the issue of the citizenship meaning nowadays, this text aims to identify to which citizenship concept the polytechnic conception belongs, considering the educational practices field and its connection to the current aspect of the world of work.
Josep Pla und Montaigne. Eine Skizze [Josep Pla and Montaigne. An outline]
Geisler, Eberhard
Zeitschrift für Katalanistik , 2006,
Abstract: Joseph Pla was a great admirer of French literature. As such, the writer Michel de Montaigne was of particular importance to him. Accordingly, Pla once remarked that he owed a plethora of fundamental philosophical knowledge to the author of Essais, as well as the ability to weigh and judge. In Pla’s opinion, the Frenchman was an ideal representative of a non-bombastic view of man and as a moralist. In the following passages, three further relations between the two authors will be reflected upon. To begin with, the depiction of the self and the emerging difficulty with the same phenomenon shall be treated; since the ego is not always present to itself, it vacillates between authenticity on the one hand, and convention and role on the other. Therefore the topic of the instability of human relation stands at the center of Montaigne’s observations as well as of Pla’s, which can evidently be traced in his tale “Contraban”; the theme of instability is counterbalanced by a certain consistency in these authors’ views. At last it demonstrates that both authors tend, with regard to their view of man, towards a policy of power decomposition. Thus they establish, with their understanding of nature and health, an inevitable counterimage (since Pla is defined by a profession towards antique cynicism and its use of the verb “badar”).
Wer war Joan Sales? Hinweis auf einen Autor [Who was Joan Sales? Hints on an author]
Geisler, Eberhard
Zeitschrift für Katalanistik , 2010,
Abstract: The major work of Joan Sales (1912-1983), the novel "Incerta glòria", has suffered a peculiar fate. In spite of the high praise expressed by Mercè Rodoreda in a letter to the author, the work was little acknowledged in Spain (the French translation, on the other hand, was more successful and was compared with the best novels by Bernanos). Only in recent years have critics increasingly surfaced, paying a befitting tribute to the book as a masterpiece and as a unique panorama of the Spanish Civil War and – along with the sequel "El vent de la nit" – the years of Francoism. The novel is clearly written from the view of the vanquished. This article outlines the life of Sales and demonstrates his approach of a critical, liberal and Catalan intellectual. As will be shown, the chief aim of the author is to experience and to seek the abundance of an intensive life, to create an intensity which is expressed in his literary style that is full of metaphors and, particularly, contrasts. A longer section of the article is dedicated to the vestiges of Kierkegaard in the novel. Within this it is above all the figure of the intellectual Soleràs who seems influenced by the Danish philosopher and progenitor of existentialism. The religious aspect is treated by Sales with particular tolerance. He rejects any form of power and hierarchy within religion and represents the theology of the cross, by attributing Christ as the God of the conquered. He defends a version of Catholicism which displays ecumenical traits. Of course, the classical criticism of religion (which viewed the childhood soul of the believer as a scandal) can be applied to the author, but he remains true to the spirit of the Gospel. At the end of the essay an eye is cast over poetry written by the author, in addition to his novel, and the implied attitude towards surrealism is investigated. From this a certain break with the surreal and the conception of the unconscious becomes evident. "Incerta glòria" is, by contrast, is monolithic and wholeheartedly successful. The novel encompasses the totality of the human and preaches a spirit for which any policies of exclusion are foreign.
Experiences of Being Non-Smoking among Adolescents in a Smoking Context  [PDF]
Ingrid Edvardsson, Dorthe Geisler, Lena Lendahls
Health (Health) , 2014, DOI: 10.4236/health.2014.611140
Abstract: Introduction: A study among Greenlandic 13-year-old showed that 68 percent for boys and 55 percent for girls, and at age 15, 46 percent of the boys and 32 percent of the girls were non-smokers. A literature review showed that the behaviour of parents and peers, attitudes and expectations were crucial factors for the smoking habits of adolescents. Young adults would more likely start smoking if their parents, older siblings and/or friends were smokers. Parental support has been proven to be a preventive factor against smoking, especially if the school and leisure centers get involved. Group pressure, directly or indirectly, is often described as the most important reason why adolescents start smoking. The purpose was to study why some adolescents choose to be smoke-free in a society where the norm is to smoke. Methods: Adolescents who were non-smokers were interviewed in focus groups. The material was analysed using content analysis. Results: The contents analysis of the text resulted in eleven categories. Based on these, four themes were developed. These themes covered areas on the reasons for being smoke-free; how the smoke-free adolescents generally felt about smokers from a society or environment perspective, and also specifically from an individual perspective, such as how smokers took up space and did not show any consideration. There was a feeling among non-smokers of not belonging and of ambivalence, as well as a perspective of the future for adolescents in Greenland and an uncertainty about what would be required for a smoke-free environment. Conclusions: In a context where the norm is to smoke, the adolescents need to make a conscious choice to be smoke-free, and there were different reasons for this choice. This choice means becoming an outsider in their group of peers as well as the overall social culture. Smokers were seen as taking up too much space, as their needs ruled and this was deemed inconsiderate.
Experimental realization of a semiconducting full Heusler compound: Fe2TiSi
Markus Meinert,Manuel P. Geisler,Jan Schmalhorst,Ulrich Heinzmann,Elke Arenholz,Walid Hetaba,Michael St?ger-Pollach,Andreas Hütten,Günter Reiss
Physics , 2014, DOI: 10.1103/PhysRevB.90.085127
Abstract: Single-phase films of the full Heusler compound Fe2TiSi have been prepared by magnetron sputtering. The compound is found to be a semiconductor with a gap of 0.4eV. The electrical resistivity has a logarithmic temperature dependence up to room temperature due to Kondo scattering of a dilute free electron gas off superparamagnetic impurities. The origin of the electron gas is extrinsic due to disorder or off-stoichiometry. Density functional theory calculations of the electronic structure are in excellent agreement with electron energy loss, optical, and x-ray absorption experiments. Fe2TiSi may find applications as a thermoelectric material.
Bimodality of light and s-elements in M4 (NGC 6121)
Sandro Villanova,Douglas Geisler
Physics , 2011,
Abstract: All Globular Clusters (GCs) studied in detail so far host two or more populations of stars. Theoretical models suggest that the second population is formed from gas polluted by processed material produced by massive stars of the first generation. However the nature of the polluter is a matter of strong debate. Several candidates have been proposed: massive main-sequence stars (fast rotating or binaries), intermediate-mass AGB stars, or SNeII. We studied red giant branch (RGB) stars in the GC M4 (NGC 6121) to measure their chemical signature. We confirm the presence of a bimodal population, first discovered by Marino et al. (2008). The two groups have different C,$^{12}$C/$^{13}$C,N,O,Na content, but share the same Li,C+N+O,Mg,Al,Si,Ca,Ti,Cr,Fe,Ni,Zr,Ba and Eu abundance. Quite surprisingly the two groups differ also in their Y abundance. The absence of a spread in $\alpha$-elements, Eu and Ba makes SNeII and AGB stars unlikely as polluters. On the other hand, massive main-sequence stars can explain the bimodality of Y through the weak s-process. This stement is confirmed independently also by literature data on Rb and Pb. Observations suggest that the mass of the polluters is between 20 and 30 M$_{\odot}$. This implies a formation time scale for the cluster of 10$\div$30 Myrs. This result is valid for M4. Other clusters like NGC 1851, M22, or $\omega$ Cen have different chemical signatures and may require other kinds of polluter.
Standard Giant Branches in the Washington Photometric System
D. Geisler,A. Sarajedini
Physics , 1998, DOI: 10.1086/300668
Abstract: We have obtained CCD photometry in the Washington system C,T1 filters for some 850,000 objects associated with 10 Galactic globular clusters and 2 old open clusters. These clusters have well-known metal abundances, spanning a metallicity range of 2.5 dex from [Fe/H]~-2.25 to +0.25 at a spacing of ~0.2 dex. Analogous to the method employed by Da Costa and Armandroff (1990, AJ, 100, 162) for V,I photometry, we then proceed to construct standard giant branches for these clusters. The Washington system technique is found to have three times the metallicity sensitivity of the V,I technique. Thus, for a given photometric accuracy, metallicities can be determined three times more precisely with the Washington technique. We find a linear relationship between (C-T1)o (at M(T1)=-2) and metallicity (on the Zinn 1985, ApJ, 293, 424 scale) exists over the full metallicity range, with an rms of only 0.04 dex. We also derive methods to determine distance, reddening and metallicity simultaneously, and note that the Washington system holds great potential for deriving accurate ages as well.
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