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V Koch

Publications and source records attributed to V Koch.

At least 19 recordsLinked to original sources
PubMed2006

Cherenkov radiation from jets in heavy-ion collisions.

The possibility of Cherenkov-like gluon bremsstrahlung in dense matter is studied. We point out that the occurrence of Cherenkov radiation in dense matter is sensitive to the presence of partonic bound states. This is illustrated by a calculation of the dispersion relation of a massless particle in a simple model in which it couples to two different massive resonance states. We further argue that detailed spectroscopy of jet correlations can directly probe the index of refraction of this matter, which in turn will provide information about the mass scale of these partonic bound states.

Journal Article↗
PubMed2005

Baryon-strangeness correlations: a diagnostic of strongly interacting matter.

The correlation between baryon number and strangeness elucidates the nature of strongly interacting matter, such as that formed transiently in high-energy nuclear collisions. This diagnostic can be extracted theoretically from lattice QCD calculations and experimentally from event-by-event fluctuations. The analysis of present lattice results above the critical temperature severely limits the presence of qq bound states, thus supporting a picture of independent (quasi)quarks.

Journal Article↗
PubMed2005

European union system for the evaluation of substances: the second version.

This publication presents major changes in the assessment of the risks of chemicals to human health and the environment as implemented in the second version of the European Union System for the Evaluation of Substances, EUSES 2.0. EUSES is a harmonised quantitative risk assessment tool for chemicals. It is the PC-implementation of the technical guidelines developed within the framework of EU chemical legislation for industrial chemicals and biocides. As such, it is designed to support decision making by risk managers in government and industry and to assist scientific institutions in the risk assessment for these substances. The development of EUSES 2.0 is a co-ordinated project of the European Chemicals Bureau, EU Member States and the European chemical industry. Several model concepts, the technical background and the user interface of EUSES have been improved considerably. Major changes in the environmental assessment such as the implementation of emission scenario documents for industrial chemicals and biocides, the addition of the marine risk assessment, the enhancement of the regional model to include global scales, and improvements in the secondary poisoning and environmental effects modelling will be discussed. The update of the human risk assessment module in EUSES focuses on the risk characterisation for both threshold and non-threshold substances with, among others, the introduction of assessment factors. The performance of EUSES is illustrated in an example showing the human and environmental risk assessment of a sanitation disinfectant for private use.

Animals↗
PubMed2001

Kinetic equation with exact charge conservation.

A kinetic master equation for multiplicity distributions is formulated for charged particles which are created or destroyed only in pairs due to the conservation of their Abelian charge. It allows one to study time evolution of the multiplicity distributions in a relativistic many-body system with arbitrary average particle multiplicities. It is shown to reproduce the equilibrium results for both canonical (rare particles) and grand canonical (abundant particles) systems. For canonical systems, the equilibrium multiplicity is much lower and the relaxation time is much shorter than the naive extrapolation from grand canonical results. Implications for chemical equilibration in heavy-ion collisions are also discussed.

Journal Article↗
PubMed2001

Alzheimer morphology is not increased in dialysis-associated encephalopathy and long-term hemodialysis.

This study examines the role of aluminium in the etiology of Alzheimer's disease (AD). Brains taken at autopsy (n = 50) from patients with a history of long-term hemodialysis (HD) and intake of aluminium (Al)-containing drugs were examined by light microscopy. Using our modified silver stain we have been able to demonstrate and clearly discriminate between AD changes and dialysis-associated encephalopathy (DAE) on paraffin sections; evaluation was done with a 3-point scale. DAE morphology is characterized by lysosome-derived intracytoplasmic, Al-containing, pathognomonic, argyrophilic inclusions in choroid plexus epithelia, cortical glia and neurons. A statistically significant difference was found between the amounts of drug-related Al ingested and the degree of DAE-related morphological change (P < 0.001). On the other hand no apparent microscopical increase in AD morphology was found. No AD changes were seen whatsoever in patients under the age of 60, despite a history of long-term HD with ingestion of "pure" Al up to 2.5 kg. Patients over 60 years of age occasionally presented with sparse deposits of beta A4 amyloid (beta A4) and/or a low incidence of AD-type neurofibrillary tangles (NFT). In accordance with CERAD criteria these were identified as normal, age-related phenomena (P < 0.001 for beta A4; P < 0.001 for NFT). Rare, isolated cases from a group of 127 long-term hemodialyzed patients have been reported previously, who presented with intermingled, clearly distinguishable lesions of both age-related AD morphology and DAE changes. Comparison of AD morphology with an age-matched control group was not statistically significant (P > 0.6 for beta A4, P > 0.7 for NFT). In our experience, Al does not cause an increase in AD morphology, at least not in terms of bioavailable Al in drugs or as a result of long-term HD.

Adult↗
PubMed2001

GREAT-ER: a new tool for management and risk assessment of chemicals in river basins. Contribution to GREAT-ER #10.

The GREAT-ER (Geo-referenced Regional Exposure Assessment Tool for European Rivers) project team has developed and validated an accurate aquatic chemical exposure prediction tool for use within environmental risk assessment schemes. The software system GREAT-ER 1.0 calculates the distribution of predicted environmental concentrations (PECs) of consumer chemicals in surface waters, for individual river stretches as well as for entire catchments. The system uses an ARC/INFO-ArcView (ESRI) based Geographical Information System (GIS) for data storage and visualization, combined with simple mathematical models for prediction of chemical fate. At present, the system contains information for four catchments in Yorkshire, one catchment in Italy, and two in Germany, while other river basins are being added. Great-ER 1.0 has been validated by comparing simulations with the results of an extensive monitoring campaign for two 'down-the-drain' chemicals, i.e. the detergent ingredients boron and Linear Alkylbenzene Sulphonate (LAS). GREAT-ER 1.0 is currently being expanded with models for the terrestrial (diffuse input), air and estaurine compartments.

Environmental Monitoring↗
PubMed2000

Charged particle ratio fluctuation as a signal for quark-gluon plasma

In this Letter we argue that the event-by-event fluctuations of the ratio of the positively charged and the negatively charged pions provide a signal for a quark-gluon plasma. The fact that quarks carry fractional charges is ultimately responsible for this distinct signal.

Journal Article↗
PubMed1995

Molecular mimicry in halothane hepatitis: biochemical and structural characterization of lipoylated autoantigens.

Exposure of human individuals to halothane causes, in about 20% of all cases, a mild transient form of hepatotoxicity. A small subset of exposed individuals, however, develops a potentially severe and life-threatening form of hepatic damage, coined halothane hepatitis. Halothane hepatitis is thought to have an immunological basis. Sera of afflicted individuals contain a wide variety of autoantibodies against hepatic proteins, in both trifluoroacetylated form (CF3CO-proteins) and, at least in part, in native form. CF3CO-proteins are elicited in the course of oxidative biotransformation of halothane, and include the trifluoroacetylated forms of protein disulfide isomerase, microsomal carboxylesterase, calreticulin, ERp72, GRP 78, and ERp99. Current evidence suggests that CF3CO-proteins arise in all halothane-exposed individuals; however, the vast majority of individuals appear to immunochemically tolerate CF3CO-proteins. The lack of immunological responsiveness of these individuals towards CF3CO-proteins might be due to tolerance, induced through the occurrence of structures in the repertoire of self-determinants, which immunochemically and structurally mimic CF3CO-proteins very closely. In fact, lipoic acid, the prosthetic group of the constitutively expressed E2 subunits of the family of mammalian 2-oxoacid dehydrogenase complexes and of protein X, was shown by immunochemical and molecular modelling analysis to be a perfect structural mimic of N6-trifluoroacetyl-L-lysine (CF3 CO-Lys), the major haptenic group of CF3CO-proteins. As a consequence of molecular mimicry, autoantibodies in patients' sera not only recognize CF3CO-proteins, but also the E2 subunit proteins of the 2-oxoacid dehydrogenase complexes and protein X, as autoantigens associated with halothane hepatitis. Furthermore, a fraction of patients with halothane hepatitis exhibit irregularities in the hepatic expression levels of these native, not trifluoroacetylated autoantigens. Collectively, these data suggest that molecular mimicry of CF3CO-Lys by lipoic acid, or the impairment thereof, might play a role in the susceptibility of individuals for the development of halothane hepatitis.

Autoantigens↗