Genetische Aufarbeitung des Marburger Video-EEG-Monitoring-Patientenkollektivs

Angehörige von Patienten mit Epilepsie haben ein erhöhtes Risiko, ebenfalls eine Epilepsie zu entwickeln. Das Risiko für Angehörige von Patienten mit genetisch (idiopathisch) generalisierten Epilepsien (GGE) ist höher als für Angehörige von Patienten mit fokalen Epilepsien mit struktureller oder unbekannter Ursache, wie die die Werte in der Literatur zeigen. Bei Forschung zur Genetik von Epilepsien ist die Erhebung der Familienanamnese ein wichtiger Bestandteil. Die Hauptfragestellung dieser Studie waren die Erhebung der Häufigkeit der positiven Familienanamnese in dem Studienkollektiv und ob die Befragung eines älteren, weiblichen Familienmitglieds die Familienanamnese verbessern könnte. Dabei wurden die Patienten im VEM (Video-EEG-Monitoring) des „Epilepsiezent-rums der Universitätsklinik Marburg“ der Jahre 2014 und 2015 untersucht. Die Ein-schlusskriterien dieser Studie erfüllten 73 Patienten. Patienten mit strukturellen Epilepsien, außer Dysplasien und Hippocampussklerosen, waren ausgeschlossen. Die Altersspanne der Patienten reichte von 11-66 Jahren. Hatten diese Patienten der Teilnahme an der „Biobank für paroxysmale neurologische Störungen“ zugestimmt, wurde versucht ein erneutes Telefongespräch mit der Erhebung der Familienanamnese durchzuführen und mit einem weiteren Familienmitglied, meist der Mutter, ebenfalls die Familienanamnese zu erheben. Die Ergebnisse dieser Studie zeigen, dass auch Patientenkollektive mit einem hohen Anteil an medikamentenrefraktären Patienten, wie im VEM, nicht selten eine positi-ve Familienanamnese aufweisen. In 37 % der Familien wurden weitere betroffene Familienmitglieder mit Epilepsien, Fieberkrämpfen oder einmaligen Anfällen be-nannt. Sicher diagnostizierte Epilepsien fanden sich bei weiteren Angehörigen bei 23 % der Familien. Die Häufigkeit von betroffenen erstgradigen Angehörigen (1,8 %) war jedoch geringer als in populationsbasierten Studien. Auch die Werte für generalisierte (2,6 %) und für fokale Epilepsien (0,8 %) lagen niedriger als ver-gleichbare Werte in der Literatur. Es ist also sehr wahrscheinlich, dass dies mit dem hohen Teil der medikamentenrefraktären Patienten in der untersuchten Kohorte zu-sammenhängt. Auch wenn die Werte im Vergleich relativ gering sind, ist es unerlässlich eine genaue Erhebung der Familienanamnese in der ärztlichen Anamnese, auch bei der Durchführung eines VEM, durchzuführen. Auswertungen der Angehörigengespräche zeigten, dass die Befragung eines älteren Angehörigen deutlich die Sensitivität für eine positive Familienanamnese erhöht, vor allem bei Patienten im Alter zwischen 10 - 40 Jahren. Daher ist die Durchführung einer Angehörigenbefragung zur Familienanamnese, wenn möglich auch im Kliniksalltag, auf Grundlage der Ergebnisse dieser Studie zu empfehlen. Hier sind vor allem Zusatzgewinne in Bezug auf Verwandte außerhalb der Kernfamilie (erstgradige Verwandte) zu erwarten. Dies kann unter anderem Hinweise auf eine genetische Komponente in der Ätiologie der Epilepsie oder auf mögliche Syndrome in der Familie geben. In Bezug auf erstgradige Angehörige gab es in dieser Studie fast keinen Zusatznutzen, da bei diesem Verwandtschaftsgrad der Austausch oft ausreichend zu sein scheint

Nuclear structure calculations for neutron-star crusts

The goal of this paper is to investigate properties of clusterized nuclear matter which is believed to be present in crusts of neutron stars at subnuclear densities. It is assumed that the whole system can be represented by the set of Wigner-Seitz cells, each containing a nucleus and an electron background under the condition of electroneutrality. The nuclear structure calculations are performed within the relativistic mean-field model with the NL3 parametrization. The first set of calculations is performed assuming the constant electron background. The evolution of neutron and proton density distributions was systematically studied along isotopic chains until very neutron-rich system beyond the neutron dripline. Then we have replaced the uniform electron background with the realistic electron distributions, obtained within the Thomas-Fermi approximation in a self-consistent way with the proton distributions. Finally, we have investigated the evolution of the $\beta$-stability valley as well as neutron and proton driplines with the electron density.Comment: 21 pages, 14 figure

Adjustment studies in self-consistent relativistic mean-field models

We investigate the influence of the adjustment procedure and the set of measured observables on the properties and predictive power of relativistic self-consistent mean-field models for the nuclear ground state. These studies are performed with the point-coupling variant of the relativistic mean-field model. We recommend optimal adjustment algorithms for the general two-part problem and we identify various trends and dependencies as well as deficiencies of current models. Consequences for model improvements are presented.Comment: 18 pages, 6 figures, revised version, accepted for publication in Nuclear Physics

Mapping exchange in relativistic Hartree-Fock

We show that formally for the standard ansatz relativistic point-coupling mean-field (RMF-PC) model a lagrangian density L is not equivalent in Hartree and Hartree-Fock approximations. The equivalency can be achieved only if we use a ``complete'' ansatz at the cost of introducing new parameters in the model. An approximate treatment of the exchange terms from standard RMF-PC indicates that these effects cannot be easily, if at all, absorbed by a Dirac-Hartree approximation.Comment: 26 pages, accepted for publication in annals of physic

Calculating the Fierz Transformation for Higher Orders

We consider the higher-order Fierz transformation, which corresponds to expanding a product of $\bar\psi\Gamma\psi$ terms into a sum of products of Dirac densities and currents. It is shown that the Fierz transformation can be obtained by solving a large system of linear equations with fractional complex coefficients, which is practical at least up to fourth power.Comment: 6 pages, 3 table

Antibaryons bound in nuclei

We study the possibility of producing a new kind of nuclear systems which in addition to ordinary nucleons contain a few antibaryons (B = p, , etc.). The properties of such systems are described within the relativistic mean field model by employing G parity transformed interactions for antibaryons. Calculations are first done for infinite systems and then for finite nuclei from 4He to 208Pb. It is demonstrated that the presence of a real antibaryon leads to a strong rearrangement of a target nucleus resulting in a significant increase of its binding energy and local compression. Noticeable e ects remain even after the antibaryon coupling constants are reduced by factor 3 4 compared to G parity motivated values. We have performed detailed calculations of the antibaryon annihilation rates in the nuclear environment by applying a kinetic approach. It is shown that due to significant reduction of the reaction Q values, the in medium annihilation rates should be strongly suppressed leading to relatively long lived antibaryon nucleus systems. Multi nucleon annihilation channels are analyzed too. We have also estimated formation probabilities of bound B + A systems in pA reactions and have found that their observation will be feasible at the future GSI antiproton facility. Several observable signatures are proposed. The possibility of producing multi quark antiquark clusters is discussed. PACS numbers: 25.43.+t, 21.10.-k, 21.30.Fe, 21.80.+

Nuclei embedded in an electron gas

The properties of nuclei embedded in an electron gas are studied within the relativistic mean-field approach. These studies are relevant for nuclear properties in astrophysical environments such as neutron-star crusts and supernova explosions. The electron gas is treated as a constant background in the Wigner-Seitz cell approximation. We investigate the stability of nuclei with respect to alpha and beta decay. Furthermore, the influence of the electronic background on spontaneous fission of heavy and superheavy nuclei is analyzed. We find that the presence of the electrons leads to stabilizing effects for both $\alpha$ decay and spontaneous fission for high electron densities. Furthermore, the screening effect shifts the proton dripline to more proton-rich nuclei, and the stability line with respect to beta decay is shifted to more neutron-rich nuclei. Implications for the creation and survival of very heavy nuclear systems are discussed.Comment: 35 pages, latex+ep

Density distributions of superheavy nuclei

We employed the Skyrme-Hartree-Fock model to investigate the density distributions and their dependence on nuclear shapes and isospins in the superheavy mass region. Different Skyrme forces were used for the calculations with a special comparison to the experimental data in $^{208}$Pb. The ground-state deformations, nuclear radii, neutron skin thicknesses and $\alpha$-decay energies were also calculated. Density distributions were discussed with the calculations of single-particle wavefunctions and shell fillings. Calculations show that deformations have considerable effects on the density distributions, with a detailed discussion on the $^{292}$120 nucleus. Earlier predictions of remarkably low central density are not supported when deformation is allowed for.Comment: 7 pages, 10 figure

The nonrelativistic limit of the relativistic point coupling model

We relate the relativistic finite range mean-field model (RMF-FR) to the point-coupling variant and compare the nonlinear density dependence. From this, the effective Hamiltonian of the nonlinear point-coupling model in the nonrelativistic limit is derived. Different from the nonrelativistic models, the nonlinearity in the relativistic models automatically yields contributions in the form of a weak density dependence not only in the central potential but also in the spin-orbit potential. The central potential affects the bulk and surface properties while the spin-orbit potential is crucial for the shell structure of finite nuclei. A modification in the Skyrme-Hartree-Fock model with a density-dependent spin-orbit potential inspired by the point-coupling model is suggested.Comment: 21 pages, latex, 1 eps figure. accepted for publication in annals of physic

On the Isovector Channels in Relativistic Point Coupling Models within the Hartree and Hartree-Fock Approximations

We investigate the consequences of Fierz transformations acting upon the contact interactions for nucleon fields occurring in relativistic point coupling models in Hartree approximation, which yield the same models but in Hartree-Fock approximation instead. We find for four-fermion interactions occurring in two existing relativistic point coupling phenomenologies that whereas in Hartree the isovector-scalar strength, corresponding to delta-meson exchange, is unnaturally small, indicating a possible new symmetry, in Hartree-Fock it is instead comparable to the isovector-vector strength corresponding to rho-meson exchange, but the sum of the two isovector coupling constants appears to be preserved in both approaches. Furthermore, in Hartree-Fock approximation, both QCD-scaled isovector coupling constants are natural (dimensionless and of order 1) whereas in Hartree approximation only that of the isovector-vector channel is natural. This indicates that it is not necessary to search for a new symmetry and, moreover, that the role of the delta-meson should be reexamined.Comment: 10 pages; accepted for publication in Nuclear Physics