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Removal of hazardous pharmaceutical from water by photocatalytic treatment
The photocatalytic abatement of hazardous pharmaceuticals has been investigated at very low concentration in the ppb range as found in wastewater and in environmental pollutants. Photocatalytic degradation of tetracycline as a model compound with titania catalysts has been studied using solarium UV-A and black light with differentially applied electric power, tetracycline and catalyst concentration. Abatement of up to 90% has been achieved after 1 hour. Adsorption of tetracycline and photochemical degradation contribute significantly to the abatement of tetracycline resulting in an immediate reduction during the initial period of treatment. Contribution of adsorption is high at very low concentration (500 ppb). Photocatalytic treatment with titania is even highly efficient in the abatement of very small concentrations of tetracycline in drinking water. © 2010 Versita Warsaw and Springer-Verlag Wien
On the Quasiparticle Description of Lattice QCD Thermodynamics
We propose a novel quasiparticle interpretation of the equation of state of
deconfined QCD at finite temperature. Using appropriate thermal masses, we
introduce a phenomenological parametrization of the onset of confinement in the
vicinity of the predicted phase transition. Lattice results of the energy
density, the pressure and the interaction measure of pure SU(3) gauge theory
are excellently reproduced. We find a relationship between the thermal energy
density of the Yang-Mills vacuum and the chromomagnetic condensate _T.
Finally, an extension to QCD with dynamical quarks is discussed. Good agreement
with lattice data for 2, 2+1 and 3 flavour QCD is obtained. We also present the
QCD equation of state for realistic quark masses.Comment: 20 pages, 10 eps figure
Two problems in thermal field theory
In this talk, I review recent progress made in two areas of thermal field
theory. In particular, I discuss various approaches for the calculation of the
quark gluon plasma thermodynamical properties, and the problem of its photon
production rate.Comment: 10 pages Latex document, 15 postscript figures. Invited talk given at
the 6th Workshop on High Energy Particle Physics, Chennai, India, 3-15 Jan
200
Lifetime of quasiparticles in hot QED plasmas
The calculation of the lifetime of quasiparticles in a QED plasma at high
temperature remains plagued with infrared divergences, even after one has taken
into account the screening corrections. The physical processes responsible for
these divergences are the collisions involving the exchange of very soft,
unscreened, magnetic photons, whose contribution is enhanced by the thermal
Bose-Einstein occupation factor. The self energy diagrams which diverge in
perturbation theory contain no internal fermion loops, but an arbitrary number
of internal magnetostatic photon lines. By generalizing the Bloch-Nordsieck
model at finite temperature, we can resum all the singular contributions of
such diagrams, and obtain the correct long time behaviour of the retarded
fermion propagator in the hot QED plasma: , where is the plasma frequency and
.Comment: 13 pages, LaTe
PrP-dependent association of prions with splenic but not circulating lymphocytes of scrapie-infected mice.
An intact immune system, and particularly the presence of mature B lymphocytes, is crucial for mouse scrapie pathogenesis in the brain after peripheral exposure. Prions are accumulated in the lymphoreticular system (LRS), but the identity of the cells containing infectivity and their role in neuroinvasion have not been determined. We show here that although prion infectivity in the spleen is associated with B and T lymphocytes and to a lesser degree with the stroma, no infectivity could be detected in lymphocytes from blood. In wild-type mice, which had been irradiated and reconstituted with PrP-deficient lymphohaematopoietic stem cells and inoculated with scrapie prions, infectivity in the spleen was present in the stroma but not in lymphocytes. Therefore, splenic B and T lymphocytes can either synthesize prions or acquire them from another source, but only when they express PrP
On the screening of static electromagnetic fields in hot QED plasmas
We study the screening of static magnetic and electric fields in massless
quantum electrodynamics (QED) and massless scalar electrodynamics (SQED) at
temperature . Various exact relations for the static polarisation tensor are
first reviewed and then verified perturbatively to fifth order (in the
coupling) in QED and fourth order in SQED, using different resummation
techniques. The magnetic and electric screening masses squared, as defined
through the pole of the static propagators, are also calculated to fifth order
in QED and fourth order in SQED, and their gauge-independence and
renormalisation-group invariance is checked. Finally, we provide arguments for
the vanishing of the magnetic mass to all orders in perturbation theory.Comment: 37 pages, 8 figure
High-resolution soft X-ray beamline ADRESS at the Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies
Concepts and technical realization of the high-resolution soft X-ray beamline ADRESS at the Swiss Light Source are described. Optimization of the optical scheme for high resolution and photon flux as well as diagnostics tools and alignment strategies are discussed
Landau-Pomeranchuk-Migdal effect in thermal field theory
In recent studies, the production rate of photons or lepton pairs by a quark
gluon plasma has been found to be enhanced due to collinear singularities. This
enhancement pattern is very dependent on rather strict collinearity conditions
between the photon and the quark momenta. It was estimated by neglecting the
collisional width of quasi-particles. In this paper, we study the modifications
of this collinear enhancement when we take into account the possibility for the
quarks to have a finite mean free path. Assuming a mean free path of order
, we find that only low invariant mass photons are
affected. The region where collision effects are important can be interpreted
as the region where the Landau-Pomeranchuk-Migdal effect plays a role in
thermal photon production by bremsstrahlung. It is found that this effect
modifies the spectrum of very energetic photons as well. Based on these results
and on a previous work on infrared singularities, we end this paper by a
reasonable physical picture for photon production by a quark gluon plasma, that
should be useful to set directions for future technical developments.Comment: 28 pages Latex document, 9 postscript figures, typos corrected,
semantics cleanup, final version to appear in Phys. Rev.
The Thermal Renormalization Group for Fermions, Universality, and the Chiral Phase-Transition
We formulate the thermal renormalization group, an implementation of the
Wilsonian RG in the real-time (CTP) formulation of finite temperature field
theory, for fermionic fields. Using a model with scalar and fermionic degrees
of freedom which should describe the two-flavor chiral phase-transition, we
discuss the mechanism behind fermion decoupling and universality at second
order transitions. It turns out that an effective mass-like term in the fermion
propagator which is due to thermal fluctuations and does not break chiral
symmetry is necessary for fermion decoupling to work. This situation is in
contrast to the high-temperature limit, where the dominance of scalar over
fermionic degrees of freedom is due to the different behavior of the
distribution functions. The mass-like contribution is the leading thermal
effect in the fermionic sector and is missed if a derivative expansion of the
fermionic propagator is performed. We also discuss results on the
phase-transition of the model considered where we find good agreement with
results from other methods.Comment: References added, minor typos correcte
Transport Theory of Massless Fields
Using the Schwinger-Keldysh technique we discuss how to derive the transport
equations for the system of massless quantum fields. We analyse the scalar
field models with quartic and cubic interaction terms. In the model
the massive quasiparticles appear due to the self-interaction of massless bare
fields. Therefore, the derivation of the transport equations strongly resembles
that one of the massive fields, but the subset of diagrams which provide the
quasiparticle mass has to be resummed. The kinetic equation for the finite
width quasiparticles is found, where, except the mean-field and collision
terms, there are terms which are absent in the standard Boltzmann equation. The
structure of these terms is discussed. In the massless model the
massive quasiparticles do not emerge and presumably there is no transport
theory corresponding to this model. It is not surprising since the
model is anyhow ill defined.Comment: 32 pages, no macro
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