University of Konstanz

About: University of Konstanz is a education organization based out in Konstanz, Baden-Württemberg, Germany. It is known for research contribution in the topics: Population & Membrane. The organization has 12115 authors who have published 27401 publications receiving 951162 citations. The organization is also known as: University of Constance & Universität Konstanz.

Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture.

Abstract: Anaerobic naphthalene degradation by a sulfate-reducing enrichment culture was studied by substrate utilization tests and identification of metabolites by gas chromatography-mass spectrometry. In substrate utilization tests, the culture was able to oxidize naphthalene, 2-methylnaphthalene, 1- and 2-naphthoic acids, phenylacetic acid, benzoic acid, cyclohexanecarboxylic acid, and cyclohex-1-ene-carboxylic acid with sulfate as the electron acceptor. Neither hydroxylated 1- or 2-naphthoic acid derivatives and 1- or 2-naphthol nor the monoaromatic compounds ortho-phthalic acid, 2-carboxy-1-phenylacetic acid, and salicylic acid were utilized by the culture within 100 days. 2-Naphthoic acid accumulated in all naphthalene-grown cultures. Reduced 2-naphthoic acid derivatives could be identified by comparison of mass spectra and coelution with commercial reference compounds such as 1,2,3,4-tetrahydro-2-naphthoic acid and chemically synthesized decahydro-2-naphthoic acid. 5,6,7,8-Tetrahydro-2-naphthoic acid and octahydro-2-naphthoic acid were tentatively identified by their mass spectra. The metabolites identified suggest a stepwise reduction of the aromatic ring system before ring cleavage. In degradation experiments with [1-13C]naphthalene or deuterated D8-naphthalene, all metabolites mentioned derived from the introduced labeled naphthalene. When a [13C]bicarbonate-buffered growth medium was used in conjunction with unlabeled naphthalene, 13C incorporation into the carboxylic group of 2-naphthoic acid was shown, indicating that activation of naphthalene by carboxylation was the initial degradation step. No ring fission products were identified.

From`spaces of place¿ to`spaces of flows¿? Territorial and functional governance in cross-border regions in Europe and North America

Abstract: To what extent are we experiencing a transformation from ‘spaces of place’ to a ‘space of flows’ as proposed by Manuel Castells? Applying his thesis to the political system leads to the following implications. Socio-economic processes of ‘glocalization’ are undermining the gate-keeper position of national governments. Furthermore, governance is becoming ‘deterritorialized’, an aspect which is characterized by Elkins as an ‘unbundling’ of identities and jurisdictions. But does this process of unbundling lead to a federal system of multi-level governance where the national level is complemented by supranational and subnational levels of governance; or does it imply an even more radical transformation towards an architecture of governance which is characterized by a proliferation of single-purpose governments with variable and flexible spatial scales? A final implication is the transformation from ‘government to governance’— which means a broader array of actors and changing modes of interaction. This article traces these theses by analysing institutions of governance in four cross-border regions in Europe and North America. In all regions we indeed find many cross-border networks and institutions undermining the national gate-keeper position. In Europe, cross-border collaboration is producing another soft, but institutionalized, comprehensive, stable and territorially-defined layer in the European ‘multi-level-system’. In North America, by contrast, only informal, fluid, specific and non-territorial institutions are evolving across national borders. Here, the territorially-based nation state is not complemented by similar kinds of political institutions, but is instead being challenged more fundamentally by new kinds of institutions: transnational socio-economic exchange networks and transnational ideological coalitions which embody enormous transformational power. In conclusion, cross-border regional governance in Europe still follows the logic of ‘spaces of place’, whereas in North America quite different ‘spaces of flows’ are emerging as complementary logics of community and institution building. Jusqu'ou s'exerce la transformation d'un ‘espace de lieux’ en ‘espace des flux’, comme le suggere Manuel Castells? L'application de cette theorie au systeme politique a plusieurs implications. Les processus socio-economiques de ‘glocalisation’ desagregent la position de garde-barriere des gouvernements nationaux. De plus, la gouvernance se ‘deterritorialise’, phenomene qu'Elkins appelle la ‘separation’ des identites et des domaines de competence. Mais a quel type de gouvernance cette ‘separation’ mene-t-elle: a un systeme federal a plusieurs niveaux ou le plan national est complete de plans supra- et infra-nationaux de gouvernance? ou a un changement plus radical vers une architecture caracterisee par une proliferation de gouvernements a finalite unique dont les echelles spatiales varient et s'adaptent? Une derniere consequence est le passage de gouvernement a gouvernance, qui se traduit par une diversification des acteurs et de nouveaux modes d'interactions. L'article retrouve ces theses en analysant des institutions de gouvernance dans quatre regions transfrontalieres europeennes et nord-americaines. Dans toutes les regions, l'etude identifie en effet de nombreux reseaux et institutions transfrontaliers qui minent la position de garde-barriere nationale. En Europe, la collaboration transfrontaliere cree une strate souple, quoique institutionnalisee, etendue, stable et aux limites territoriales definies dans le ‘systeme europeen a plusieurs niveaux’. En Amerique du Nord, en revanche, n'interviennent a travers les frontieres que des institutions informelles, fluides, specifiques et non-territoriales; l'Etat-nation lie au territoire n'est pas complete d'institutions politiques de types similaires, etant plutot profondement mis en cause par des institutions d'un genre nouveau: reseaux d'echanges socio-economiques et coalitions ideologiques transnationaux qui expriment une enorme dynamique de transformation. Pour conclure, la gouvernance regionale transfrontaliere en Europe obeit encore a la logique des ‘espaces de lieux’ tandis qu'en Amerique du Nord, des ‘espaces de flux’ tout a fait differents apparaissent dans une logique complementaire de construction de communautes et d'institutions.

Josephson effect in ballistic graphene

Abstract: We solve the Dirac\char21{}Bogoliubov\char21{}de Gennes equation in an impurity-free superconductor\char21{}normal-metal\char21{}superconductor junction, to determine the maximal supercurrent ${I}_{c}$ that can flow through an undoped strip of graphene with heavily doped superconducting electrodes. The result ${I}_{c}\ensuremath{\simeq}(W∕L)e{\ensuremath{\Delta}}_{0}∕\ensuremath{\hbar}$ is determined by the superconducting gap ${\ensuremath{\Delta}}_{0}$ and by the aspect ratio of the junction (length $L$ small relative to the width $W$ and to the superconducting coherence length). Moving away from the Dirac point of zero doping, we recover the usual ballistic result ${I}_{c}\ensuremath{\simeq}(W∕{\ensuremath{\lambda}}_{F})e{\ensuremath{\Delta}}_{0}∕\ensuremath{\hbar}$, in which the Fermi wavelength ${\ensuremath{\lambda}}_{F}$ takes over from $L$. The product ${I}_{c}{R}_{\mathrm{N}}\ensuremath{\simeq}{\ensuremath{\Delta}}_{0}∕e$ of the critical current and normal-state resistance retains its universal value (up to a numerical prefactor) on approaching the Dirac point.

Porin from bacterial and mitochondrial outer membranes.

Abstract: The outer membrane of gram-negative bacteria acts as a molecular filter with defined exclusion limit for hydrophilic substances. The exclusion limit is dependent on the type of bacteria and has for enteric bacteria like Escherichia coli and Salmonella typhimurium a value between 600 and 800 Daltons, whereas molecules with molecular weights up to 6000 can penetrate the outer membrane of Pseudomonas aeruginosa. The molecular sieving properties result from the presence of a class of major proteins called porins which form trimers of identical subunits in the outer membrane. The porin trimers most likely contain only one large but well-defined pore with a diameter between 1.2 and 2 nm. Mitochondria are presumably descendents of gram-negative bacteria. The outer membrane of mitochondria contains in agreement with this hypothesis large pores which are permeable for hydrophilic substances with molecular weights up to 6000. The mitochondrial porins are processed by the cell and have molecular weights around 30,000 Daltons. There exists some evidence that the pore is controlled by electric fields and metabolic processes.

Environmental Policy Convergence: The Impact of International Harmonization, Transnational Communication, and Regulatory Competition

Abstract: In recent years, there is growing interest in the study of cross-national policy convergence. Yet we still have a limited understanding of the phenomenon: Do we observe convergence of policies at all? Under which conditions can we expect that domestic policies converge or rather develop further apart? In this article, we address this research deficit. From a theoretical perspective, we concentrate on the explanatory power of three factors, namely international harmonization, transnational communication, and regulatory competition. In empirical terms, we analyze if and to what extent we can observe convergence of environmental policies across twenty-four industrialized countries between 1970 and 2000. We find an impressive degree of environmental policy convergence between the countries under investigation. This development is mainly caused by international harmonization and, to a considerable degree, also by transnational communication, whereas regulatory competition does not seem to play a role.