Mechanismus der enzymatischen Freisetzung von Acetaldehyd aus “aktivem Acetaldehyd” (α-hydroxyaethyl-2-thiaminpyrophosphat)

1. 1.Die Freisetzung von Acetaldehyd aus “Aktivem Acetaldehyd” mit gereinigter Apopyruvatdecarboxylase aus Bierhefe wird durch. Thiaminpyrophosphat gehemmt. Diese Konkurrenzhemmung erklärt (zumindest teilweise) die langsame Freisetzung von Acetaldehyd beim enzymatischen Umsatz von Präparaten, die viel Thiamin-pyrophosphat enthalten. 2. 2. Die Freisetzung von Acetaldehyd aus “Aktivem Acetaldehyd” mit Apo-carboxylase erfolgt nicht in einer früher von uns diskutierten Austauschreaktion mit Pyruvat, sondern in einer direkten Reaktion: Aktiver Acetaldehyd å Acetaldehyd + TPP.1. 1. The enzymic formation of acetaldehyde from α-hydroxyethyl thiamine pyrophosphate with purified apopyrubate decarboxylase from yeast is inhibited by thiamine pyrophosphate. This inhibition explains (at least partly) the slow enzymic production of acetaldehyde from α-hydroxyethyl thiamine pyrophosphate preparations containing a considerable amount of thiamine pyrophosphate. 2. 2. The enzymic formation of acetaldehyde from α-hydroxyethyl thiamine pyrophosphate with apocarboxylase does not take place in form of an exchange reaction with pyruvate, as discussed earlier, but in form of the direct reaction: α-hydroxyethyl thiamine pyrophosphate → acetaldehyde + thiamine pyrophosphate

Linear Imperfections and Operational Aspects Induced by the D1 Multipole Errors for the LHC Upgrade Phase I

In addition to the dynamic aperture as a general machine parameter that has to be optimized in the LHC upgrade machine, strong lower order multipoles will lead to a series of problems for the operation of the machine. A direct influence on the linear beam optics (beta beating, tune shift and coupling) from the a2, b2 multipoles is evident. Equally important however are the multipole coefficients of the next higher order n=3 via the feed down effect. The foreseen half crossing angle of about 205 µrad at the IP creates large offsets in the D1 magnet that finally lead again to a strong a2, b2 errors. The estimates presented in this paper show a distortion in the order of several percent for the beta beat and a considerable shift of the working point. Even after compensation of these effects an influence on the machine performance is expected during machine operation and a further reduction of the multipole coefficients, especially in the case of the D1 magnet, might be needed

Green's Relations in Finite Transformation Semigroups

We consider the complexity of Green's relations when the semigroup is given by transformations on a finite set. Green's relations can be defined by reachability in the (right/left/two-sided) Cayley graph. The equivalence classes then correspond to the strongly connected components. It is not difficult to show that, in the worst case, the number of equivalence classes is in the same order of magnitude as the number of elements. Another important parameter is the maximal length of a chain of components. Our main contribution is an exponential lower bound for this parameter. There is a simple construction for an arbitrary set of generators. However, the proof for constant alphabet is rather involved. Our results also apply to automata and their syntactic semigroups.Comment: Full version of a paper submitted to CSR 2017 on 2016-12-1

Are Suburban Firms More Likely to Discriminate Against African Americans?

This paper presents a test of the hypothesis that employers in suburban locations are more likely to discriminate against African Americans than are employers located in central cities. Using a difference-in-difference framework, we compare central-city/suburban differences in racial hiring outcomes for firms where a white person is in charge of hiring (white employers, for short) to similar geographic differences in outcomes for firms where a black person is in charge of hiring (black employers). We find that both suburban black and white employers hire fewer blacks than their central-city counterparts. Moreover, the central-city/suburban hiring gap among black employers is as large as, or larger than, that of white employers. Suburban black employers, however, receive many more applications from blacks and hire more blacks than do white firms in either location.

Phase Rotation, Cooling And Acceleration Of Muon Beams: A Comparison Of Different Approaches

Experimental and theoretical activities are underway at CERN with the aim of examining the feasibility of a very-high-flux neutrino source. In the present scheme, a high-power proton beam (some 4 MW) bombards a target where pions are produced. The pions are collected and decay to muons under controlled optical condition. The muons are cooled and accelerated to a final energy of 50 GeV before being injected into a decay ring where they decay under well-defined conditions of energy and emittance. We present the most challenging parts of the whole scenario, the muon capture, the ionisation-cooling and the first stage of the muon acceleration. Different schemes, their performance and the technical challenges are compared.Comment: LINAC 2000 CONFERENCE, paper ID No. THC1

Towards Collaborative Conceptual Exploration

In domains with high knowledge distribution a natural objective is to create principle foundations for collaborative interactive learning environments. We present a first mathematical characterization of a collaborative learning group, a consortium, based on closure systems of attribute sets and the well-known attribute exploration algorithm from formal concept analysis. To this end, we introduce (weak) local experts for subdomains of a given knowledge domain. These entities are able to refute and potentially accept a given (implicational) query for some closure system that is a restriction of the whole domain. On this we build up a consortial expert and show first insights about the ability of such an expert to answer queries. Furthermore, we depict techniques on how to cope with falsely accepted implications and on combining counterexamples. Using notions from combinatorial design theory we further expand those insights as far as providing first results on the decidability problem if a given consortium is able to explore some target domain. Applications in conceptual knowledge acquisition as well as in collaborative interactive ontology learning are at hand.Comment: 15 pages, 2 figure

Decay of scalar turbulence revisited

We demonstrate that at long times the rate of passive scalar decay in a turbulent, or simply chaotic, flow is dominated by regions (in real space or in inverse space) where mixing is less efficient. We examine two situations. The first is of a spatially homogeneous stationary turbulent flow with both viscous and inertial scales present. It is shown that at large times scalar fluctuations decay algebraically in time at all spatial scales (particularly in the viscous range, where the velocity is smooth). The second example explains chaotic stationary flow in a disk/pipe. The boundary region of the flow controls the long-time decay, which is algebraic at some transient times, but becomes exponential, with the decay rate dependent on the scalar diffusion coefficient, at longer times.Comment: 4 pages, no figure

Measurements of heavy ion beam losses from collimation

The collimation efficiency for Pb ion beams in the LHC is predicted to be lower than requirements. Nuclear fragmentation and electromagnetic dissociation in the primary collimators create fragments with a wide range of Z/A ratios, which are not intercepted by the secondary collimators but lost where the dispersion has grown sufficiently large. In this article we present measurements and simulations of loss patterns generated by a prototype LHC collimator in the CERN SPS. Measurements were performed at two different energies and angles of the collimator. We also compare with proton loss maps and find a qualitative difference between Pb ions and protons, with the maximum loss rate observed at different places in the ring. This behavior was predicted by simulations and provides a valuable benchmark of our understanding of ion beam losses caused by collimation.Comment: 12 pages, 20 figure