1,123 research outputs found
Quantitative modeling of \textit{in situ} x-ray reflectivity during organic molecule thin film growth
Synchrotron-based x-ray reflectivity is increasingly employed as an
\textit{in situ} probe of surface morphology during thin film growth, but
complete interpretation of the results requires modeling the growth process.
Many models have been developed and employed for this purpose, yet no detailed,
comparative studies of their scope and accuracy exists in the literature. Using
experimental data obtained from hyperthermal deposition of pentane and
diindenoperylene (DIP) on SiO, we compare and contrast three such models,
both with each other and with detailed characterization of the surface
morphology using ex-situ atomic force microscopy (AFM). These two systems each
exhibit particular phenomena of broader interest: pentacene/SiO exhibits a
rapid transition from rough to smooth growth. DIP/SiO, under the conditions
employed here, exhibits growth rate acceleration due to a different sticking
probability between the substrate and film. In general, \textit{independent of
which model is used}, we find good agreement between the surface morphology
obtained from fits to the \insitu x-ray data with the actual morphology at
early times. This agreement deteriorates at later time, once the root-mean
squared (rms) film roughness exceeds about 1 ML. A second observation is that,
because layer coverages are under-determined by the evolution of a single point
on the reflectivity curve, we find that the best fits to reflectivity data ---
corresponding to the lowest values of --- do not necessarily yield
the best agreement between simulated and measured surface morphologies.
Instead, it appears critical that the model reproduce all local extrema in the
data. In addition to showing that layer morphologies can be extracted from a
minimal set of data, the methodology established here provides a basis for
improving models of multilayer growth by comparison to real systems.Comment: 34 pages (double-spaced, including figures and references), 10
figures, 3 appendice
Methods of predicting relapsing hemorrhage.
In this article the authors presented their own original methods for predicting ulcerous gastroduodenal bleeding defended by Patent of Ukraine. The implementation of these procedures led to substantial lowing of recurrent hamorrhage rate – more than twice. All methods have pathogenetic foundation and are based on ulcerogenesis mechanisms revealed during the longlasting complex clinical and experimental research. In such a way surgeons obtain some possibilities of early diagnostics of bleeding relapses and adequate treatment and effective hemorrhage prevention accordingly.
О пределах вершинно-симметрических графов и их автоморфизмах
Using a simple but rather general method of constructing Cayley graphs with trivial vertex stabilizers, we give an example of an infinite locally finite Cayley graph (and, hence, an example of an infinite connected locally finite vertex-symmetric unimodular graph) which is isolated in the space of connected locally finite vertex-symmetric graphs. We also give examples of Cayley graphs which are not isolated in this space but are isolated from the set of connected vertex-symmetric finite graphs. © 2019 Krasovskii Institute of Mathematics and Mechanics. All right reserved
Sensitivities of Low Energy Reactor Neutrino Experiments
The low energy part of the reactor neutrino spectra has not been
experimentally measured. Its uncertainties limit the sensitivities in certain
reactor neutrino experiments. The origin of these uncertainties are discussed,
and the effects on measurements of neutrino interactions with electrons and
nuclei are studied. Comparisons are made with existing results. In particular,
the discrepancies between previous measurements with Standard Model
expectations can be explained by an under-estimation of the low energy reactor
neutrino spectra. To optimize the experimental sensitivities, measurements for
\nuebar-e cross-sections should focus on events with large (1.5 MeV)
recoil energy while those for neutrino magnetic moment searches should be based
on events 100 keV. The merits and attainable accuracies for
neutrino-electron scattering experiments using artificial neutrino sources are
discussed.Comment: 25 pages, 9 figure
Ez-response as a monitor of a Baikal rift fault electrical resistivity: 3D modelling studies
3D numerical studies have shown that the vertical voltage above the Baikal deep-water fault is detectable and that respective transfer functions, Ez-responses, are sensitive to the electrical resistivity changes of the fault, i.e.
these functions appear actually informative with respect to the resistivity «breath» of the fault. It means that if the fault resistivity changed, conventional electromagnetic instruments would be able to detect this fact by measurement
of the vertical electric field, Ez, or the vertical electric voltage just above the fault as well as horizontal magnetic field on the shore. Other electromagnetic field components (Ex, Ey, Hz) do not seem to be sensitive to the resistivity changes in such a thin fault (as wide as 500 m). On the other hand, such changes are thought to
be able to indicate a change of a stress state in the earthquake preparation zone. Besides, the vertical profile at the bottom of Lake Baikal is suitable for electromagnetic monitoring of the fault electrical resistivity changes.
Altogether, the vertical voltage above the deep-water fault might be one of earthquake precursors
Methods of predicting relapsing hemorrhage.
In this article the authors presented their own original methods for predicting ulcerous gastroduodenal bleeding defended by Patent of Ukraine. The implementation of these procedures led to substantial lowing of recurrent hamorrhage rate – more than twice. All methods have pathogenetic foundation and are based on ulcerogenesis mechanisms revealed during the longlasting complex clinical and experimental research. In such a way surgeons obtain some possibilities of early diagnostics of bleeding relapses and adequate treatment and effective hemorrhage prevention accordingly
Quantum treatment of neutrino in background matter
Motivated by the need of elaboration of the quantum theory of the spin light
of neutrino in matter (), we have studied in more detail the exact
solutions of the Dirac equation for neutrinos moving in the background matter.
These exact neutrino wavefunctions form a basis for a rather powerful method of
investigation of different neutrino processes in matter, which is similar to
the Furry representation of quantum electrodynamics in external fields. Within
this method we also derive the corresponding Dirac equation for an electron
moving in matter and consider the electromagnetic radiation ("spin light of
electron in matter", ) that can be emitted by the electron in this case.Comment: 10 pages, in: Proceedings of QFEXT'05 (The Seventh Workshop on
Quantum Field Theory under the Influence of External Conditions, IEEC, CSIC
and University of Barcelona, Barcelona, Catalonia, Spain, 5-9 September
2005.), ed. by Emilio Elizalde and Sergei Odintsov; published in Journal of
Physics
- …