331 research outputs found
Objective appraisal of tolerance to ventriculography with various radiocontrast media (according to electronystagmography data)
The vestibulo oculomotor reflex (nystagmus) was recorded by means of electronystagmography in 33 neurosurgical patients in dynamics prior to and after ventriculography. For contrasting the ventricular system a water soluble medium (Conrey, dimer X or Amipak) was used in 18 patients and contrast mixtures of water soluble agents in combination with Myodil emulsion in 15. It was established that after ventriculography with water soluble media the trunk vestibular reactions in all types of nystagmus grew frequently and sharply and the vestibulovegetative reactions increased markedly
Staphylinids (Coleoptera, Staphylinidae) of Ukrainian metropolises
During hundreds of years, in large cities man has been forming a specific urban environment with original species composition of insect communities, including the most diverse group of predatory beetles – Staphylinidae family. Kyiv, Kharkiv, Dnipro are the three most populated cities of Ukraine. In the urban cenoses of these cities, over 140 species from 66 genera of Staphylinidae have been recorded. The total of 69 species (43 genera) were recorded in Kyiv, 67 (39 genera) in Dnipro and 66 (37 genera) in Kharkiv. Among them, , eight species in the catalogue of Palearctic staphylinds had not been previously recorded for Ukraine: Arpedium quadrum Grav., Atheta laticeps Thomson, Medon apicalis Kraatz, Ocalea rivularis Müll., Philonthus salinus Kiesenwetter, Quedius invreae Gridelli, Tasgius pedator Grav. and Xantholinus gallicus Coiffait. By number, common species accounted for 29 in Dnipro, 21 in Kyiv and 19 in Kharkiv. In all the metropolises, two species (Staphylinus caesareus Cederhjelm and Drusilla canaliculata (F.)) were identified as eudominants. Dominants and subdominants comprised 18–25 species. Almost two thirds of the fauna of staphylinids of the cities was classified as rare species. The lowest faunistic similarity was seen between the staphylinids of the urban cenoses of Dnipro and those in Kyiv and Kharkiv (15.3% and 17.5%), similarity was higher for Staphylinidae of Kyiv and Kharkiv (36.0%). Similarity by common species of staphylinids for Kyiv and Kharkiv equaled 73.9%, 28.2% for Dnipro and Kyiv and 37.1% for Dnipro and Kharkiv. The article offers a review of species diversity, number and ecological structure (biotopic confinedness, hygrothermal preference) of typical species of staphylinids in different urban cenoses of Kharkiv. Differences in qualitative-quantitative and ecological structures of staphylinids are related to the diversity of the conditions in a particular urban cenoses. The commonest representatives of the family in the metropolises were polytopic mesophilous carnivorous species
Sum rules and electrodynamics of high-Tc cuprates in the pseudogap state
We explore connections between the electronic density of states (DOS) in a
conducting system and the frequency dependence of the scattering rate
inferred from infrared spectroscopy. We show that changes in
the DOS upon the development of energy gaps can be reliably tracked through the
examination of the spectra using the sum rules discussed in
the text. Applying this analysis to the charge dynamics in high- cuprates
we found radically different trends in the evolution of the DOS in the
pseudogap state and in the superconducting state.Comment: 4 pages, 3 figure
Optical Conductivity in a Simple Model of Pseudogap State in Two-Dimensional System
We present calculation of optical conductivity in a simple model of
electronic spectrum of two-dimensional system with "hot patches" on the Fermi
surface, leading to non Fermi-liquid renormalization of the spectral density
(pseudogap) on these patches. It is shown that this model qualitatively
reproduces basic anomalies of optical experiments in the pseudogap state of
copper oxides.Comment: 12 pages, 6 figures, RevTeX 3.0, Postscript figures attache
Marginal Fermi liquid analysis of 300 K reflectance of Bi2Sr2CaCu2O8+x
We use 300 K reflectance data to investigate the normal-state electrodynamics
of the high temperature superconductor BiSrCaCuO
over a wide range of doping levels. The data show that at this temperature the
free carriers are coupled to a continuous spectrum of fluctuations. Assuming
the Marginal Fermi Liquid (MFL) form as a first approximation for the
fluctuation spectrum, the doping-dependent coupling constant can
be estimated directly from the slope of the reflectance spectrum. We find that
decreases smoothly with the hole doping level, from underdoped
samples with ( K) where to overdoped
samples with , ( K) where . An analysis of
the intercept and curvature of the reflectance spectrum shows deviations from
the MFL spectrum symmetrically placed at the optimal doping point . The
Kubo formula for the conductivity gives a better fit to the experiments with
the MFL spectrum up to 2000 cm and with an additional Drude component or
an additional Lorentz component up to 7000 cm. By comparing three
different model fits we conclude that the MFL channel is necessary for a good
fit to the reflectance data. Finally, we note that the monotonic variation of
the reflectance slope with doping provides us with an independent measure of
the doping level for the Bi-2212 system.Comment: 11 pages, 11 figure
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