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The kaon nuclear optical potential is studied including the effect of the Θ+ pentaquark. The one-nucleon contribution is obtained using an extension of the Jülich meson-exchange potential as bare kaon–nucleon interaction. Significant differences between a fully self-consistent calculation and the usually employed low-density Tρ approach are observed. The influence of the one-nucleon absorption process, KN→Θ+, on the kaon optical potential is negligible due to the small width of the pentaquark. In contrast, the two-nucleon mechanism, KNN→Θ+N, estimated from the coupling of the pentaquark to a two-meson cloud, provides the required amount of additional kaon absorption to reconcile with data the systematically low K+-nucleus reaction cross sections found by the theoretical models.
We solve the coupled Wong Yang–Mills equations for both U(1) and SU(2) gauge groups and anisotropic particle momentum distributions numerically on a lattice. For weak fields with initial energy density much smaller than that of the particles we confirm the existence of plasma instabilities and of exponential growth of the fields which has been discussed previously. Also, the SU(2) case is qualitatively similar to U(1), and we do find significant “abelianization” of the non-Abelian fields during the period of exponential growth. However, the effect nearly disappears when the fields are strong. This is because of the very rapid isotropization of the particle momenta by deflection in a strong field on time scales comparable to that for the development of Yang–Mills instabilities. This mechanism for isotropization may lead to smaller entropy increase than collisions and multiplication of hard gluons, which is interesting for the phenomenology of high-energy heavy-ion collisions.
Large extra dimensions could lower the Planck scale to experimentally accessible values. Not only is the Planck scale the energy scale at which effects of modified gravity become important. The Planck length also acts as a minimal length in nature, providing a natural ultraviolet cutoff and a limit to the possible resolution of spacetime.
In this Letter we examine the influence of the minimal length on the Casimir energy between two plates.
Alternative NADH dehydrogenases (NADH:ubiquinone oxidoreductases) are single subunit respiratory chain enzymes found in plant and fungal mitochondria and in many bacteria. It is unclear how these peripheral membrane proteins interact with their hydrophobic substrate ubiquinone. Known inhibitors of alternative NADH dehydrogenases bind with rather low affinities. We have identified 1-hydroxy-2-dodecyl-4(1H)quinolone as a high affinity inhibitor of alternative NADH dehydrogenase from Yarrowia lipolytica. Using this compound, we have analyzed the bisubstrate and inhibition kinetics for NADH and decylubiquinone. We found that the kinetics of alternative NADH dehydrogenase follow a ping-pong mechanism. This suggests that NADH and the ubiquinone headgroup interact with the same binding pocket in an alternating fashion.
Generation of reactive oxygen species (ROS) is increasingly recognized as an important cellular process involved in numerous physiological and pathophysiological processes. Complex I (NADH:ubiquinone oxidoreductase) is considered as one of the major sources of ROS within mitochondria. Yet, the exact site and mechanism of superoxide production by this large membrane-bound multiprotein complex has remained controversial. Here we show that isolated complex I from Yarrowia lipolytica forms superoxide at a rate of 0.15% of the rate measured for catalytic turnover. Superoxide production is not inhibited by ubiquinone analogous inhibitors. Because mutant complex I lacking a detectable iron-sulfur cluster N2 exhibited the same rate of ROS production, this terminal redox center could be excluded as a source of electrons. From the effect of different ubiquinone derivatives and pH on this side reaction of complex I we concluded that oxygen accepts electrons from FMNH or FMN semiquinone either directly or via more hydrophilic ubiquinone derivatives.
The transporter associated with antigen processing (TAP)-like (TAPL, ABCB9) belongs to the ATP-binding cassette transporter family, which translocates a vast variety of solutes across membranes. The function of this half-size transporter has not yet been determined. Here, we show that TAPL forms a homodimeric complex, which translocates peptides across the membrane. Peptide transport strictly requires ATP hydrolysis. The transport follows Michaelis-Menten kinetics with low affinity and high capacity. Different nucleotides bind and energize the transport with a slight predilection for purine bases. The peptide specificity is very broad, ranging from 6-mer up to at least 59-mer peptides with a preference for 23-mers. Peptides are recognized via their backbone, including the free N and C termini as well as side chain interactions. Although related to TAP, TAPL is unique as far as its interaction partners, transport properties, and substrate specificities are concerned, thus excluding that TAPL is part of the peptide-loading complex in the classic route of antigen processing via major histocompatibility complex class I molecules.
Benzene solutions of Me3SnCl when exposed to moisture yield the adduct Me3SnCl·Me3SnOH·H2O. This adduct represents an intermediate in Me3SnCl hydrolysis. The structure of Me3SnCl·Me3SnOH·H2O features an array of Me3Sn units connected alternatingly by bridging Cl and OH ligands.
Die "lyrische Operette" 'Semele' erscheint zum ersten Mal in der von Schiller anonym herausgegebenen Lyriksammlung 'Anthologie auf das Jahr 1782'. [...] Im Falle der Ovidschen Vorlage handelt es sich - zumal in der der Zeit um 1780 - um ein brisantes Thema, nämlich um die "Götterwollust" des Menschen. [...] Schiller [...] behält das brisante Problem bei, exponiert und steigert es sogar, um es erst danach im Menschheitlichen aufzuheben.
Im Folgenden möchte ich durch Einordnung von Brentanos "Geschichte vom braven Kasperl und dem schönen Annerl" in eine Geschichte des Wissens (Medizin, Recht, Mythologie) zeigen, dass die Organisation der Erzählung der Dynamik zweier gegenlaufiger Textbewegungen geschuldet ist: erstens dem Ausbruch einer rechtlichen Krise als Folge einer fehlenden (in einem gewissen Sinne unmöglichen) sozialen Integration von Sexualität, Kriminalität und Psychopathologie, zweitens den Versuchen, mit einer neuen Ordnung auf diese Krise zu reagieren. Auf der einen Seite stehen die Verbrechen von Kasperl und Annerl, Selbstmord und Kindsmord, ihre psychische und (außer-)gesellschaftliche Genese sowie ihre Folgen, auf der anderen Seite die narrative Bewältigung der Ereignisse durch den Erzähler und die rechtliche durch den Fürsten.
Expansion in die Natur : zum Verhältnis von "ars" und "natura" bei Paracelsus und im Paracelsismus
(2005)
Wenn Paracelsus Naturwissenschaft oder magica als eine Handlung definiert, die "aus ihr", der Natur, ist, diese aber "mer, dan" ihr selbst "zu zu legen ist", steigert und "bessert", dann geschieht dies auf Basis aristotelischer Argumente, die im 13. Jahrhundert auf neuplatonische Weise so kombiniert werden, daß die aristotelischen Vorgaben mit der Vorstellung einer aktiven sympathetischen Teilhabe des Menschen am Kosmos harmonisieren. Diese Überformung wird in der Frühen Neuzeit noch einmal weiterentwickelt. Es sind die protestantische Mystik mit und gegen Luther und die Auslagerung ihrer häretischen Tendenzen in die Naturwissenschaft, die der Theorie von der Steigerung der Natur aus ihrer Mitte die Bedeutung einer wechselseitigen souverinen Teilhabe verleihen.