53 research outputs found
A method of improving clinical work with patients with peptic ulcer of stomach and duodenum
Objective: identification of risk groups for development of complications of ulcerous disease of stomach and duodenum.Material and Methods. We used data from the official statistical reports of the health Committee of the city of Saratov and the logs of incoming and departures/deaths of patients in the surgical and gastroenterology clinics of the city (1976-2006). The parameters of the prevalence of gastric ulcer and duodenal ulcer and its complications in the population of different age groups are analyzed. Linear regression analysis, odds ratio, and analysis of the speed characteristics of the dynamics of the studied parameters in time (mean, minimum, maximum speed, range of the dynamics of the studied parameters, the number of changes in the sign of the speed of change in the prevalence of the studied parameters) were applied. Results. It was found that the probability of complications of the disease is higher among those age groups, which are characterized by a frequent change in the sign of the rate of change in the prevalence of the pathology. The necessity of age accounting in stratification of the risk of complications of gastric ulcer and duodenal ulcer and the multiplicity of medical observation of persons of different ages with this pathology, taking into account the analytical parameters of the disease. Conclusion. The scheme of determining the multiplicity of dispensary examinations of patients with gastric ulcer and duodenal ulcer is proposed.</div
Cross-subject integration of biology and ecology in course work
The aggravation of the ecological situation on a global scale has led to the need for greening all areas, i.e. to the need to take into account the laws and requirements of ecology - in all sciences, production and in all human activities. However, ecology as a subject does not exist in the modern Russian school. The interdisciplinary optional course "Omsk Region - My Native Land" helps the children to broaden their horizons and gain knowledge about their region, about basic environmental concepts and patterns. The developed elective is an integrated course that incorporates the foundations of various disciplines of the natural science cycle. The purpose of the optional course is to motivate schoolchildren to acquire new knowledge in the field of ecology, biology and geography based on regional content, to stimulate and organize educational and research activities; to form ecological thinking and ecological culture among students of the basic school. Increasing the level of ecological culture of students in the process of formation of systemic natural science knowledge and familiarization with educational and research activities
Multiband light emission and nanoscale chemical analyses of carbonized fumed silica
Fumed silica with a specific area of 295 m(2)/g was carbonized by successive phenyltrimethoxysilane treatments followed by annealing in inert atmosphere up to 650 degrees C. Emission, excitation, kinetics, and photo-induced bleaching effects were investigated by steady state and time-resolved photoluminescence spectroscopies. The local chemistry was also studied by infrared transmission spectroscopy. Strong ultraviolet and visible photoluminescence was observed in the samples after the chemical treatments/modifications and thermal annealing. It has been shown that ultraviolet photoluminescence in chemically modified fumed silica is associated with phenyl groups, while near ultraviolet and visible emission in annealed samples originated from inorganic pyrolytic carbon precipitates dispersed in the silica host matrix. Two types of emission bands were identified as a function of the annealing temperature: one is in the near UV and the other is in the visible range. Based on the emission/excitation analysis of these two bands, as well as on correlations with the synthesis conditions, a structural-energy concept of light-emitting centers has been proposed. According to this model, the light-emitting centers are associated with carbon clusters that can be bonded or adsorbed on the silica surface. This has been validated by a detailed (S)TEM-electron energy-loss spectroscopy study, confirming the inhomogeneous distribution of nanoscale carbon precipitates at the surface of the silica nanoparticles. These carbon precipitates are mostly amorphous although they possess some degree of graphitization and local order. Finally, the fraction of sp(2) carbon in these nanoclusters has been estimated to be close to 80%. Published by AIP Publishing
Two-loop approximation in the Coulomb blockade problem
We study Coulomb blockade (CB) oscillations in the thermodynamics of a
metallic grain which is connected to a lead by a tunneling contact with a large
conductance in a wide temperature range, ,
where is the charging energy. Using the instanton analysis and the
renormalization group we obtain the temperature dependence of the amplitude of
CB oscillations which differs from the previously obtained results. Assuming
that at the oscillation amplitude weakly depends on
temperature we estimate the magnitude of CB oscillations in the ground state
energy as .Comment: 10 pages, 3 figure
Weak Charge Quantization on Superconducting Islands
We consider the Coulomb blockade on a superconductive quantum dot strongly
coupled to a lead through a tunnelling barrier and/or normal diffusive metal.
Andreev transport of the correlated pairs leads to quantum fluctuations of the
charge on the dot. These fluctuations result in exponential renormalization of
the effective charging energy. We employ two complimentary ways to approach the
problem, leading to the coinciding results: the instanton and the functional RG
treatment of the non-linear sigma model. We also derive the charging energy
renormalization in terms of arbitrary transmission matrix of the multi-channel
interface.Comment: 21 pages, 4 eps figures, RevTe
Theory of Interaction Effects in N-S Junctions out of Equilibrium
We consider a normal metal - superconductor (N-S) junction in the regime,
when electrons in the normal metal are driven out of equilibrium. We show that
the non-equilibrium fluctuations of the electron density in the N-layer cause
the fluctuations of the phase of the order parameter in the S-layer. As a
result, the density of states in the superconductor deviates from the BCS form,
most notably the density of states in the gap becomes finite. This effect can
be viewed as a result of the time reversal symmetry breaking due to the
non-equilibrium, and can be described in terms of a low energy collective mode
of the junction, which couples normal currents in N-layer and supercurrents.
This mode is analogous to the Schmid-Sch\"{o}n mode. To interpret their
measurements of the tunneling current, Pothier {\em et. al} [Phys. Rev. Lett.
{\bf 79}, 3490 (1997)] had to assume that the energy relaxation rate in the
normal metal is surprisingly high. The broadening of the BCS singularity of the
density of states in the S-layer manifest itself similarly to the broadening of
the distribution function. Mechanism suggested here can be a possible
explanation of this experimental puzzle. We also propose an independent
experiment to test our explanation.Comment: 16 pages, 2 .eps figure
Subcarrier Wave Quantum Key Distribution in Telecommunication Network with Bitrate 800 kbit/s
In the course of work on creating the first quantum communication network in Russia we demonstrated quantum key distribution in metropolitan optical network infrastructure. A single-pass subcarrier wave quantum cryptography scheme was used in the experiments. BB84 protocol with strong reference was chosen for performing key distribution. The registered sifted key rate in an optical cable with 1.5 dB loss was 800 Kbit/s. Signal visibility exceeded 98%, and quantum bit error rate value was 1%. The achieved result is a record for this type of systems
Coulomb blockade in metallic grains at large conductance
We study Coulomb blockade effects in the thermodynamic quantities of a weakly
disordered metallic grain coupled to a metallic lead by a tunneling contact
with a large conductance . We consider the case of broken time-reversal
symmetry and obtain expressions for both the {\em ensemble averaged} amplitude
of the Coulomb blockade oscillations of the thermodynamic potential and the
correlator of its {\em mesoscopic fluctuations} for a finite mean level spacing
in the grain. We develop a novel method which allows for an exact
evaluation of the functional integral arising from disorder averaging. The
results and the method are applicable in the temperature range .Comment: 18 pages, 3 figures (revised version
Shot Noise at High Temperatures
We consider the possibility of measuring non-equilibrium properties of the
current correlation functions at high temperatures (and small bias). Through
the example of the third cumulant of the current () we demonstrate
that odd order correlation functions represent non-equilibrium physics even at
small external bias and high temperatures. We calculate for a quasi-one-dimensional diffusive constriction. We calculate the
scaling function in two regimes: when the scattering processes are purely
elastic and when the inelastic electron-electron scattering is strong. In both
cases we find that interpolates between two constants. In the low (high)
temperature limit is strongly (weakly) enhanced (suppressed) by the
electron-electron scattering.Comment: 11 pages 4 fig. submitted to Phys. Rev.
Electron transport through interacting quantum dots
We present a detailed theoretical investigation of the effect of Coulomb
interactions on electron transport through quantum dots and double barrier
structures connected to a voltage source via an arbitrary linear impedance.
Combining real time path integral techniques with the scattering matrix
approach we derive the effective action and evaluate the current-voltage
characteristics of quantum dots at sufficiently large conductances. Our
analysis reveals a reach variety of different regimes which we specify in
details for the case of chaotic quantum dots. At sufficiently low energies the
interaction correction to the current depends logarithmically on temperature
and voltage. We identify two different logarithmic regimes with the crossover
between them occurring at energies of order of the inverse dwell time of
electrons in the dot. We also analyze the frequency-dependent shot noise in
chaotic quantum dots and elucidate its direct relation to interaction effects
in mesoscopic electron transport.Comment: 21 pages, 4 figures. References added, discussion slightly extende
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