Neue Linsensysteme und Implantate [meeting abstract]
- Verein Rheinisch-Westfälischer Augenärzte. 175. Versammlung des Vereins Rheinisch-Westfälischer Augenärzte. Bochum, 01.-02.02.2013.
Im Rahmen des Vortrags wird zunächst ein Überblick über die aktuell angewandten Linsensysteme in der (refraktiven) Kataraktchirurgie sowie im Rahmen des RLA gesprochen. Hierzu zählen die monofokalen sphärischen Standardlinsen, aber auch asphärische, torische und multifokale Implantate.
Speziell wird auf die Ergebnisse einer Studie zu einem neuen multifokalen-torischen Implantat eingegangen. Der Schwerpunkt des Vortrages liegt dann weiterhin auf den trifokalen Korrektionsmöglichkeiten. Zum einen wird die sog. binokulare Trifokalität, bei der zwei multifokale Intraokularlinsen unterschiedlicher Addition implantiert werden, besprochen. Durch die Anpassung jeweils eines Auges an den Intermediär- bzw. Nahbereich soll so bei verringerten optischen Phänomenen ein deutliches Sehen in drei Hauptdistanzen ermöglicht werden. Weiterhin befasst sich der Vortrag aber auch mit den neuen echten trifokalen Optiksystemen, welche ebenfalls deutliches Sehen in verschiedenen Entfernungen gewährleisten können.
Im dritten Teil des Vortrages werden aktuelle Langzeitergebnisse aus einer FDA Studie zur Evaluation einer kammerwinkelgestützten phaken Intraokularlinse, mit speziellem Augenmerk auf den cornealen Endothelzellverlust, sowie eine neuartige sulcusgestütze phake Intraokularlinse mit zentralem Loch zur Glaukomvermeidung vorgestellt.
7th German Conference on Chemoinformatics: 25 CIC-Workshop : Goslar, Germany, 6 - 8 November 2011 ; meeting abstracts
Design of dual ligands using excessive pharmacophore query alignment : from 7th German Conference on Chemoinformatics: 25 CIC-Workshop Goslar, Germany, 6 - 8 November 2011
Estel la Buscató
- Oral presentation
Dual- or multi-target ligands have gained increased attention in the past years due to several advantages, including more simple pharmacokinetic and phamarcodynamic properties compared to a combined application of several drugs. Furthermore multi-target ligands often possess improved efficacy . We present a new approach for the discovery of dual-target ligands using aligned pharmacophore models combined with a shape-based scoring. Starting with two sets of known active compounds for each target, a number of different pharmacophore models is generated and subjected to pairwise graph-based alignment using the Kabsch-Algorithm [2,3]. Since a compound may be able to bind to different targets in different conformations, the algorithm aligns pairs of pharmacophore models sharing the same features which are not necessarily at the exactly same spatial distance. Using the aligned models, a pharmacophore search on a multi-conformation-database is performed to find compounds matching both models. The potentially “dual” ligands are scored by a shape-based comparison with the known active molecules using ShaEP .
Using this approach, we performed a prospective fragment-based virtual screening for dual 5-LO/sEH inhibitors. Both enzymes play an important role in the arachidonic acid cascade and are involved in inflammatory processes, pain, cardiovascular diseases and allergic reactions [5,6]. Beside several new selective inhibitors we were able to find a compound inhibiting both enzymes in low micromolar concentrations. The results indicate that the idea of aligned pharmacophore models can be successfully employed for the discovery of dual-target ligands.
GCC2011 – 25 years of computational chemistry meetings : from 7th German Conference on Chemoinformatics: 25 CIC-Workshop
Goslar, Germany, 6 - 8 November 2011
The QCD phase diagram at zero and small baryon density
- I review recent developments in determining the QCD phase diagram by means of lattice simulations.
Since the invention of methods to side-step the sign problem a few years ago, a number
of additional variants have been proposed, and progress has been made towards understanding
some of the systematics involved. All available techniques agree on the transition temperature
as a function of density in the regime mq/T <~1. There are by now four calculations with signals
for a critical point, two of them at similar parameter values and with consistent results. However,
it also emerges that the location of the critical point is exceedingly quark mass sensitive. At the
same time sizeable finite volume, cut-off and step size effects have been uncovered, demanding
additional investigations with exact algorithms on larger and finer lattices before quantitative conclusions
can be drawn. Depending on the sign of these corrections, there is ample room for the
eventual phase diagram to look as expected or also quite different, with no critical point at all.
QCD equation of state and dark matter
- The QCD equation of state is not often discussed in cosmology. However, the relic density of
weakly interacting massive particles (WIMPs) depends on the entropy and the expansion rate of
the Universe when they freeze out, at a temperature in the range 400 MeV – 40GeV, where QCD
corrections are still important. We use recent analytic and lattice calculations of the QCD pressure
to produce a new equation of state suitable for use in relic density calculations. As an example,
we show that relic densities calculated by the dark matter package DarkSUSY receive corrections
of several per cent, within the observational accuracy of the Planck CMB mission, due for launch
Strong coupling expansion for Yang-Mills theory at finite temperature
- Euclidean strong coupling expansion of the partition function is applied to lattice Yang-Mills theory
at finite temperature, i.e. for lattices with a compactified temporal direction. The expansions
have a finite radius of convergence and thus are valid only for b <bc, where bc denotes the nearest
singularity of the free energy on the real axis. The accessible temperature range is thus the
confined regime up to the deconfinement transition. We have calculated the first few orders of
these expansions of the free energy density as well as the screening masses for the gauge groups
SU(2) and SU(3). The resulting free energy series can be summed up and corresponds to a glueball
gas of the lowest mass glueballs up to the calculated order. Our result can be used to fix
the lower integration constant for Monte Carlo calculations of the thermodynamic pressure via
the integral method, and shows from first principles that in the confined phase this constant is
indeed exponentially small. Similarly, our results also explain the weak temperature dependence
of glueball screening masses below Tc, as observed in Monte Carlo simulations. Possibilities and
difficulties in extracting bc from the series are discussed.
Twisted mass QCD at finite temperature
Maria Paola Lombardo
- We discuss the use of Wilson fermions with twisted mass for simulations of QCD thermodynamics.
As a prerequisite for a future analysis of the finite-temperature transition making use
of automatic O(a) improvement, we investigate the phase structure in the space spanned by the
hopping parameter k , the coupling b , and the twisted mass parameter m. We present results for
Nf = 2 degenerate quarks on a 163×8 lattice, for which we investigate the possibility of an Aoki
phase existing at strong coupling and vanishing m, as well as of a thermal phase transition at
moderate gauge couplings and non-vanishing m.
Exploring the QCD phase diagram
- Lattice simulations employing reweighting and Taylor expansion techniques have predicted a
(m;T)-phase diagram according to general expectations, with an analytic quark-hadron crossover
at m =0 turning into a first order transition at some critical chemical potential mE. By contrast, recent
simulations using imgainary m followed by analytic continuation obtained a critical structure
in the fmu;d;ms;T;mg parameter space favouring the absence of a critical point and first order line.
I review the evidence for the latter scenario, arguing that the various raw data are not inconsistent
with each other. Rather, the discrepancy appears when attempting to extract continuum results
from the coarse (Nt =4) lattices simulated so far, and can be explained by cut-off effects. New (as
yet unpublished) data are presented, which for Nf = 3 and on Nt = 4 confirm the scenario without
a critical point. Moreover, simulations on finer Nt = 6 lattices show that even if there is a critical
point, continuum extrapolation moves it to significantly larger values of mE than anticipated on
The finite-temperature phase structure of lattice QCD with twisted-mass Wilson fermions
Maria Paola Lombardo
- We report progress in our exploration of the finite-temperature phase structure of two-flavour lattice
QCD with twisted-mass Wilson fermions and a tree-level Symanzik-improved gauge action
for a temporal lattice size Nt = 8. Extending our investigations to a wider region of parameter
space we gain a global view of the rich phase structure. We identify the finite temperature transition/
crossover for a non-vanishing twisted-mass parameter in the neighbourhood of the zerotemperature
critical line at sufficiently high b . Our findings are consistent with Creutz’s conjecture
of a conical shape of the finite temperature transition surface. Comparing with NLO lattice
cPT we achieve an improved understanding of this shape.