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STONE 6: Artificial Sedimentary Meteorites in Space
The STONE 6 experiment demonstrated the survivability of carbonaceous and microfossiliferous martian analogue sediments during atmospheric re-entry. Doped endoliths died but their carbonised cells remained
Semantics of the Painted Image in Hugo von Hofmannsthal’s Tod des Tizian
Form theories in Hofmannstahl’s aesthetic program aim at a reciprocal empowerment of life and art. Titian’s last painting in Tod des Tizian (1892) has to express a concept of unity and totality of all living things. Most disciples are not able to understand this, as they can’t get free of the model of existence of the aesthete, who rejects life, perceiving it as abandoned to chaos and disorder, but is incapable of replacing it with any other form because he exalts art as an object of mere idolatry, as a pure and simple instrument of defence from the pitfalls of life
Microscopic Models for Ultrarelativistic Heavy Ion Collisions
In this paper, the concepts of microscopic transport theory are introduced
and the features and shortcomings of the most commonly used ansatzes are
discussed. In particular, the Ultrarelativistic Quantum Molecular Dynamics
(UrQMD) transport model is described in great detail. Based on the same
principles as QMD and RQMD, it incorporates a vastly extended collision term
with full baryon-antibaryon symmetry, 55 baryon and 32 meson species. Isospin
is explicitly treated for all hadrons. The range of applicability stretches
from GeV/nucleon, allowing for
a consistent calculation of excitation functions from the intermediate energy
domain up to ultrarelativistic energies. The main physics topics under
discussion are stopping, particle production and collective flow.Comment: 129 pages, pagestyle changed using US letter (8.5x11 in) format. The
whole paper (13 Mb ps file) could also be obtained from
ftp://ftp.th.physik.uni-frankfurt.de/pub/urqmd/ppnp2.ps.g
Nonradiative limitations to plasmon propagation in chains of metallic nanoparticles
This is the author accepted manuscript. The final version is available from the American Physical Society via the DOI in this recordWe investigate the collective plasmonic modes in a chain of metallic nanoparticles that are coupled by near-field interactions. The size- and momentum-dependent nonradiative Landau damping and radiative decay rates are calculated analytically within an open quantum system approach. These decay rates determine the excitation propagation along the chain. In particular, the behavior of the radiative decay rate as a function of the plasmon wavelength leads to a transition from an exponential decay of the collective excitation for short distances to an algebraic decay for large distances. Importantly, we show that the exponential decay is of a purely nonradiative origin. Our transparent model enables us to provide analytical expressions for the polarization-dependent plasmon excitation profile along the chain and for the associated propagation length. Our theoretical analysis constitutes an important step in the quest for the optimal conditions for plasmonic propagation in nanoparticle chains.CNRSAN
Local Thermal and Chemical Equilibration and the Equation of State in Relativistic Heavy Ion Collisions
Thermodynamical variables and their time evolution are studied for central
relativistic heavy ion collisions from 10.7 to 160 AGeV in the microscopic
Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). The UrQMD model
exhibits drastic deviations from equilibrium during the early high density
phase of the collision. Local thermal and chemical equilibration of the
hadronic matter seems to be established only at later stages of the quasi-
isentropic expansion in the central reaction cell with volume 125 fm.
distributions at all collision energies for with a unique
Baryon energy spectra in this cell are approximately reproduced by Boltzmann
rapidly dropping temperature. At these times the equation of state has a simple
form: . At 160 AGeV the strong deviation from
chemical equilibrium is found for mesons, especially for pions, even at the
late stage of the reaction. The final enhancement of pions is supported by
experimental data.Comment: 17 Pages, LaTex, 8 eps figures. Talk given at SQM'98 conference,
20-24 July 1998, Padova, Italy, submitted to J. Phys.
Equation of State, Spectra and Composition of Hot and Dense Infinite Hadronic Matter in a Microscopic Transport Model
Equilibrium properties of infinite relativistic hadron matter are
investigated using the Ultrarelativistic Quantum Molecular Dynamics (UrQMD)
model. The simulations are performed in a box with periodic boundary
conditions. Equilibration times depend critically on energy and baryon
densities. Energy spectra of various hadronic species are shown to be isotropic
and consistent with a single temperature in equilibrium. The variation of
energy density versus temperature shows a Hagedorn-like behavior with a
limiting temperature of 13010 MeV. Comparison of abundances of different
particle species to ideal hadron gas model predictions show good agreement only
if detailed balance is implemented for all channels. At low energy densities,
high mass resonances are not relevant; however, their importance raises with
increasing energy density. The relevance of these different conceptual
frameworks for any interpretation of experimental data is questioned.Comment: Latex, 20 pages including 6 eps-figure
Are we close to the QGP? - Hadrochemical vs. microscopic analysis of particle production in ultrarelativistic heavy ion collisions
Ratios of hadronic abundances are analyzed for pp and nucleus-nucleus
collisions at sqrt(s)=20 GeV using the microscopic transport model UrQMD.
Secondary interactions significantly change the primordial hadronic cocktail of
the system. A comparison to data shows a strong dependence on rapidity. Without
assuming thermal and chemical equilibrium, predicted hadron yields and ratios
agree with many of the data, the few observed discrepancies are discussed.Comment: 12 pages, 4 figure
Equation of state of resonance-rich matter in the central cell in heavy-ion collisions at =200 AGeV
The equilibration of hot and dense nuclear matter produced in the central
cell of central Au+Au collisions at RHIC ( AGeV) energies is
studied within a microscopic transport model. The pressure in the cell becomes
isotropic at fm/ after beginning of the collision. Within the
next 15 fm/ the expansion of matter in the cell proceeds almost
isentropically with the entropy per baryon ratio , and the
equation of state in the plane has a very simple form,
. Comparison with the statistical model of an ideal hadron gas
indicates that the time fm/c may be too short to reach the fully
equilibrated state. Particularly, the creation of long-lived resonance-rich
matter in the cell decelerates the relaxation to chemical equilibrium. This
resonance-abundant state can be detected experimentally after the thermal
freeze-out of particles.Comment: LATEX, 21 pages incl. 7 figure
Structure-Activity Relationships of Triple-Action Platinum(IV) Prodrugs with Albumin-Binding Properties and Immunomodulating Ligands
Chemotherapy with
platinum complexes is essential for clinical
anticancer therapy. However, due to side effects and drug resistance,
further drug improvement is urgently needed. Herein, we report on
triple-action platinum(IV) prodrugs, which, in addition to tumor targeting via maleimide-mediated albumin binding, release the immunomodulatory
ligand 1-methyl-d-tryptophan (1-MDT). Unexpectedly, structure–activity
relationship analysis showed that the mode of 1-MDT conjugation distinctly
impacts the reducibility and thus activation of the prodrugs. This
in turn affected ligand release, pharmacokinetic properties, efficiency
of immunomodulation, and the anticancer activity in vitro and in a mouse model in vivo. Moreover, we could
demonstrate that the design of albumin-targeted multi-modal prodrugs
using platinum(IV) is a promising strategy to enhance the cellular
uptake of bioactive ligands with low cell permeability (1-MDT) and
to improve their selective delivery into the malignant tissue. This
will allow tumor-specific anticancer therapy supported by a favorably
tuned immune microenvironment
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