42 research outputs found
The critical field and specific heat in the electron- and hole-doped graphene superconductors
Doping is one of the most prominent techniques to alter properties of a given
material. Herein, the influence of the electron- and hole-doping on the
selected superconducting properties of graphene are considered. In details, the
Migdal-Eliashberg formalism is employed to analyze the specific heat and the
critical magnetic field in the representative case of graphene doped with
nitrogen or boron, respectively. It is found that the electron doping is much
more favorable in terms of enhancing the aforementioned properties than its
hole counterpart. These findings are appropriately summarized by the means of
the dimensionless thermodynamic ratios, familiar in the
Bardeen-Cooper-Schrieffer theory. To this end, the perspectives for future
research on superconductivity in graphene are drawn.Comment: 5 pages, 2 figures, 1 tabl
The superconducting energy gap in the hole-doped graphene beyond the Migdal's theory
In this work we analyze impact of non-adiabatic effects on the
superconducting energy gap in the hole-doped graphene. By using the Eliashberg
formalism beyond the Migdal's theorem, we present that the non-adiabatic
effects strongly influence the superconducting energy gap in the exemplary
boron-doped graphene. In particular, the non-adiabatic effects, as represented
by the first order vertex corrections to the electron-phonon interaction,
supplement Coulomb depairing correlations and suppress the superconducting
state. In summary, the obtained results confirm previous studies on
superconductivity in two-dimensional materials and show that the corresponding
superconducting phase may be notably affected by the non-adiabatic effects.Comment: conference material, 4 pages, 2 figure
Entropy of financial time series due to the shock of war
The concept of entropy is not uniquely relevant to the statistical mechanics
but among others it can play pivotal role in the analysis of a time series,
particularly the stock market data. In this area sudden events are especially
interesting as they describe abrupt data changes which may have long-lasting
effects. Here, we investigate the impact of such events on the entropy of
financial time series. As a case study we assume data of polish stock market in
the context of its main cumulative index. This index is discussed for the
finite time periods before and after outbreak of the 2022 Russian invasion of
Ukraine, acting as the sudden event. The analysis allows us to validate the
entropy-based methodology in assessing market changes as driven by the extreme
external factors. We show that qualitative features of market changes can be
captured quantitatively in terms of the entropy. In addition to that, the
magnitude of the impact is analysed over various time periods in terms of the
introduced entropic index. To this end, the present work also attempts to
answer whether or not the recent war can be considered as a reason or at least
catalyst to the current economic crisis.Comment: 8 pages, 5 figure
FIELD-INDUCED MAGNETIZATION IN Ho0.53Er0.47Co3.04Ni1.95
The magnetization process of Ho0.53Er0.47Co3.04Ni1.95 single crystals was investigated in a field up to 10 T from 4.2 to 300 K as a function of the angle between the c-axis and the magnetic field. The magnetic spin structure is interpreted in a crystal-field-with-exchange-field model
Optimization of fMRI Analysis of Speech Areas in Pre- and Postoperative Diagnostics
Functional magnetic resonance imaging (fMRI) was used to characterize relevant functional areas adjacent to the tumor what has important implications for surgical intervention. The aim of our study was to evaluate the functional areas of Broca and Wernicke responsible for production and understanding the speech which are very important from the point of view patients quality life using different variants of analysis available in the SPM package. Brain activity imaging with FWE controlling seems to be more appropriate than this with un uncorrected thresholds in clinical diagnostic. However analysis in the SPM should be carried out with great care taking into consideration that results can be influenced by parameters used in statistical approaches
Twenty years of medical physics in Silesia
Fizyka Medyczna w Polsce ma już 50 letnią tradycję i wykładana jest na wielu uczelniach. Fizyka Medyczna na Śląsku jako specjalność na kierunku Fizyka po raz pierwszy pojawiła się już ponad dwadzieścia lat temu. Sympozjum „XX-lecie Fizyki Medycznej na Śląsku”, które odbyło się w dniach 6–7 czerwca 2014 roku w Śląskim Międzyuczelnianym Centrum Edukacji i Badań Interdyscyplinarnych, poświęcone było m.in. podsumowaniu tych dwudziestu lat pracy. Przy okazji wspomniano również o osiągnięciach Zakładu Fizyki Medycznej Uniwersytetu Śląskiego, a także interdyscyplinarnej współpracy z innymi uczelniami, klinikami oraz placówkami, zajmującymi się fizyką medyczną w kraju. Sympozjum pokazało także, jak wielkie zmiany w fizyce medycznej zaszły w ciągu tych dwudziestu lat.Medical Physics in Poland has almost 50-year history and many Universities offer education in this field. Medical Physics as a specialty in Physics education in the Silesian University started twenty years ago. From 6th to 7th June 2014 in the Silesian Education and Interdisciplinary Research Center a symposium devoted to “XX years of Medical Physics in Silesia Region” was held. The achievements of the Department of Medical Physics of the Silesian University were discussed, as well as its cooperation with other universities, hospitals and institutions connected to medical physics in Poland. The Symposium showed also the changes in the field of medical physics observed over the last two decades
XPS Investigation of Superconductors
The analysis of the valence band photoemission spectra of (0≤x≤1) is presented. The valence bands are mainly plotted for Ni 3d, Y 4d and Dy 4f contributions, according to theoretical predictions. The valence bands of compounds markedly change shape with the x parameter, especially in the binding energy region from 3 eV to 14 eV. For large content of Dy (above 55%) the valence band is predominant by Dy 4f states whereas Ni 3d states govern the valence band of yttrium rich compounds. Changing in domination of valence sub-band correlates with plot of superconducting transition temperature with Dy concentration