418 research outputs found
"Digital petrophysics" in studies of porosity properties of low- permeable reservoirs
The article focuses on study in the properties of low-permeable reservoirs. The object of the research is the Bazhenov formation rocks taken from a well drilled in an oilfield of the West Siberian basin. A series of experiments were carried out to determine porosity of rocks by different methods: the helium saturation, nuclear magnetic resonance (NMR), microcomputed tomography (mCT). A comparative analysis was conducted to assess the efficiency of different methods. The obtained results have shown that common methods of petrophysical surveys are insufficient for carbonate-argillaceous Low-permeable rocks, containing a great amount of hand extractable organic matter. The additional data received by the mCT method gave an opportunity to increase sufficiently the reliability of the research results. We have concluded that the most efficient method for the study of low-permeable rocks is a combined use of the NMR and the mCT
Non-Linear Vibrations in Nuclei
We have perfomed Time Dependant Hartree-Fock (TDHF) calculations on the non
linear response of nuclei. We have shown that quadrupole (and dipole) motion
produces monopole (and quadrupole) oscillations in all atomic nuclei. We have
shown that these findings can be interpreted as a large coupling between one
and two phonon states leading to large anharmonicities.Comment: 4 pages, 3 figure
Investigation of LiFeAs by means of "Break-junction" Technique
In our tunneling investigation using Andreev superconductor - normal metal -
superconductor contacts on LiFeAs single crystals we observed two reproducible
independent subharmonic gap structures at dynamic conductance characteristics.
From these results, we can derive the energy of the large superconducting gap
meV and the small gap meV at
K for the K (the contact area
critical temperature which deviation causes the variation of ). The
BCS-ratio is found to be , whereas
results from induced superconductivity in the bands
with the small gap.Comment: 7 pages, 5 figures. Published in Pis'ma v ZhETF 95, 604-610 (2012
Strong fragmentation of low-energy electromagnetic excitation strength in Sn
Results of nuclear resonance fluorescence experiments on Sn are
reported. More than 50 transitions with MeV were
detected indicating a strong fragmentation of the electromagnetic excitation
strength. For the first time microscopic calculations making use of a complete
configuration space for low-lying states are performed in heavy odd-mass
spherical nuclei. The theoretical predictions are in good agreement with the
data. It is concluded that although the E1 transitions are the strongest ones
also M1 and E2 decays contribute substantially to the observed spectra. In
contrast to the neighboring even Sn, in Sn the
component of the two-phonon quintuplet built on top of
the 1/2 ground state is proved to be strongly fragmented.Comment: 4 pages, 3 figure
Coherent propagation of interacting particles in a random potential: the Mechanism of enhancement
Coherent propagation of two interacting particles in weak random
potential is considered. An accurate estimate of the matrix element of
interaction in the basis of localized states leads to mapping onto the relevant
matrix model. This mapping allows to clarify the mechanism of enhancement of
the localization length which turns out to be rather different from the one
considered in the literature. Although the existence of enhancement is
transparent, an analytical solution of the matrix model was found only for very
short samples. For a more realistic situation numerical simulations were
performed. The result of these simulations is consistent with l_{2}/l_1 \sim
l_1^{\gamma} , where and are the single and two particle
localization lengths and the exponent depends on the strength of the
interaction. In particular, in the limit of strong particle-particle
interaction there is no enhancement of the coherent propagation at all ().Comment: 23 pages, REVTEX, 3 eps figures, improved version accepted for
publication in Phys. Rev.
Study of the Two-Gap Superconductivity in GdO(F)FeAs by ScS-Andreev Spectroscopy
Current-voltage characteristics and dynamic conductance of the superconductor
- constriction - superconductor junctions in GdO(F)FeAs polycrystalline samples
with critical temperatures Tc^local = 46 - 53 K were investigated. Two
superconducting gaps, the large Delta_L = 10.5 +- 2 meV, and the small one
Delta_S = 2.3 +- 0.4 meV were clearly observed at T = 4.2 K. The
2Delta_L/kTc^local = 5.5 +- 1 ratio gives support to the strong coupling
mechanism which is responsible for the high Tc value. Temperature dependence of
the large gap Delta_L(T) indicates the presence of intrinsic proximity effect
(in k-space) between two superconducting condensates.Comment: 7 pages, 6 figures. Submitted to Journal of Physics: Conference
Serie
Search for the electric dipole excitations to the multiplet in Sn
The odd-mass Sn nucleus was investigated in nuclear resonance
fluorescence experiments up to an endpoint energy of the incident photon
spectrum of 4.1 MeV at the bremsstrahlung facility of the Stuttgart University.
More than 50 mainly hitherto unknown levels were found. From the measurement of
the scattering cross sections model independent absolute electric dipole
excitation strengths were extracted. The measured angular distributions
suggested the spins of 11 excited levels. Quasi-particle phonon model
calculations including a complete configuration space were performed for the
first time for a heavy odd-mass spherical nucleus. These calculations give a
clear insight in the fragmentation and distribution of the , , and
excitation strength in the low energy region. It is proven that the
component of the two-phonon quintuplet built on
top of the ground state is strongly fragmented. The theoretical
calculations are consistent with the experimental data.Comment: 10 pages, 5 figure
Observation of Multi-Gap Superconductivity in GdO(F)FeAs by Andreev Spectroscopy
We have studied current-voltage characteristics of Andreev contacts in
polycrystalline GdOFFeAs samples with bulk critical
temperature = (52.5 \pm 1)K using break-junction technique. The data
obtained cannot be described within the single-gap approach and suggests the
existence of a multi-gap superconductivity in this compound. The large and
small superconducting gap values estimated at T = 4.2K are {\Delta}L = 10.5 \pm
2 meV and {\Delta}S = 2.3 \pm 0.4 meV, respectively.Comment: 5 pages, 4 figures, submitted to JETP Letter
The first experience kidney radiofrequency ablation
Radiofrequency ablation (RFA) has been proposed as an alternative to open surgery for the treatment of small renal tumors in elderly patients with anamnesis record and a method for better hemostasis during operations on the kidney. In the article presents data on completed transactions using the system of 'Cool-tip'. The advantages of using this technique compared to traditional operations. In Sverdlovsk Regional Clinical Hospital №1, Department of Urologic Oncology from 2008. holds 11 operatsy using the RFA. Using the system for the RFA is reasonable to perform a variety of operational, conservative surgery for kidney tumor.Радиочастотная абляция (РИА) была предложена как альтернатива открытой операции для лечения небольших опухолей почек у пожилых больных с отягощенным соматическим анамнезом и как методика для обеспечения надежного гемостаза при резекции почек. В работе представлены данные о выполненных операциях с использованием системы “Cool-tip™”. Обоснованы преимущества использования данной методики в сравнении с традиционными операциями. В клинике урологии УГМА при ГУЗ «С0КБ№1» с 2008г. выполнено 11 операций с использованием аппарата для РИА. Использование системы РЧА является оправданной при выполнении различных оперативных пособий при опухолях почки
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