7,730 research outputs found
Orbital Properties of Sr3Ru2O7 and Related Ruthenates Probed by 17O-NMR
We report a site-separated O-NMR study of the layered perovskite
ruthenate SrRuO, which exhibits nearly two-dimensional transport
properties and itinerant metamagnetism at low temperatures. The local hole
occupancies and the spin densities in the oxygen orbitals are obtained by
means of tight-binding analyses of electric field gradients and anisotropic
Knight shifts. These quantities are compared with two other layered perovskite
ruthenates: the two-dimensional paramagnet SrRuO and the
three-dimensional ferromagnet SrRuO. The hole occupancies at the oxygen
sites are very large, about one hole per ruthenium atom. This is due to the
strong covalent character of the Ru-O bonding in this compound. The magnitude
of the hole occupancy might be related to the rotation or tilt of the RuO
octahedra. The spin densities at the oxygen sites are also large, 20-40% of the
bulk susceptibilities, but in contrast to the hole occupancies, the spin
densities strongly depend on the dimensionality. This result suggests that the
density-of-states at the oxygen sites plays an essential role for the
understanding of the complex magnetism found in the layered perovskite
ruthenates.Comment: 9 pages, 5 figures, to be published in Phys. Rev.
Quantum System under Periodic Perturbation: Effect of Environment
In many physical situations the behavior of a quantum system is affected by
interaction with a larger environment. We develop, using the method of
influence functional, how to deduce the density matrix of the quantum system
incorporating the effect of environment. After introducing characterization of
the environment by spectral weight, we first devise schemes to approximate the
spectral weight, and then a perturbation method in field theory models, in
order to approximately describe the environment. All of these approximate
models may be classified as extended Ohmic models of dissipation whose
differences are in the high frequency part.
The quantum system we deal with in the present work is a general class of
harmonic oscillators with arbitrary time dependent frequency. The late time
behavior of the system is well described by an approximation that employs a
localized friction in the dissipative part of the correlation function
appearing in the influence functional. The density matrix of the quantum system
is then determined in terms of a single classical solution obtained with the
time dependent frequency. With this one can compute the entropy, the energy
distribution function, and other physical quantities of the system in a closed
form.
Specific application is made to the case of periodically varying frequency.
This dynamical system has a remarkable property when the environmental
interaction is switched off: Effect of the parametric resonance gives rise to
an exponential growth of the populated number in higher excitation levels, or
particle production in field theory models. The effect of the environment is
investigated for this dynamical system and it is demonstrated that there existsComment: 55 pages, LATEX file plus 13 PS figures. A few calculational
mistatkes and corresponding figure 1 in field theory model corrected and some
changes made for publication in Phys. Rev.D (in press
The cross-frequency mediation mechanism of intracortical information transactions
In a seminal paper by von Stein and Sarnthein (2000), it was hypothesized
that "bottom-up" information processing of "content" elicits local, high
frequency (beta-gamma) oscillations, whereas "top-down" processing is
"contextual", characterized by large scale integration spanning distant
cortical regions, and implemented by slower frequency (theta-alpha)
oscillations. This corresponds to a mechanism of cortical information
transactions, where synchronization of beta-gamma oscillations between distant
cortical regions is mediated by widespread theta-alpha oscillations. It is the
aim of this paper to express this hypothesis quantitatively, in terms of a
model that will allow testing this type of information transaction mechanism.
The basic methodology used here corresponds to statistical mediation analysis,
originally developed by (Baron and Kenny 1986). We generalize the classical
mediator model to the case of multivariate complex-valued data, consisting of
the discrete Fourier transform coefficients of signals of electric neuronal
activity, at different frequencies, and at different cortical locations. The
"mediation effect" is quantified here in a novel way, as the product of "dual
frequency RV-coupling coefficients", that were introduced in (Pascual-Marqui et
al 2016, http://arxiv.org/abs/1603.05343). Relevant statistical procedures are
presented for testing the cross-frequency mediation mechanism in general, and
in particular for testing the von Stein & Sarnthein hypothesis.Comment: https://doi.org/10.1101/119362 licensed as CC-BY-NC-ND 4.0
International license: http://creativecommons.org/licenses/by-nc-nd/4.0
Analytic models for mechanotransduction: gating a mechanosensitive channel
Analytic estimates for the forces and free energy generated by bilayer
deformation reveal a compelling and intuitive model for MscL channel gating
analogous to the nucleation of a second phase. We argue that the competition
between hydrophobic mismatch and tension results in a surprisingly rich story
which can provide both a quantitative comparison to measurements of opening
tension for MscL when reconstituted in bilayers of different thickness and
qualitative insights into the function of the MscL channel and other
transmembrane proteins
New Kinetic Equation for Pair-annihilating Particles: Generalization of the Boltzmann Equation
A convenient form of kinetic equation is derived for pair annihilation of
heavy stable particles relevant to the dark matter problem in cosmology. The
kinetic equation thus derived extends the on-shell Boltzmann equation in a most
straightforward way, including the off-shell effect. A detailed balance
equation for the equilibrium abundance is further analyzed. Perturbative
analysis of this equation supports a previous result for the equilibrium
abundance using the thermal field theory, and gives the temperature power
dependence of equilibrium value at low temperatures. Estimate of the relic
abundance is possible using this new equilibrium abundance in the sudden
freeze-out approximation.Comment: 19 pages, LATEX file with 2 PS figure
Promotive effects of hyperthermia on the Ρytostatic activity to ehrlich ascites tumor cells by diverse delta-alkyllactones
To evaluate promotive effects of hyperthermia on antitumor activity of new delta-alkyllactones (DALs) of low molecular weight (184β254 Da), chemically synthesized, which are different from natural macrocyclic lactones of high molecular weight (348β439 Da), such as camptothecin and sultriecin. Methods: A suspension of Ehrlich ascites tumor (EAT) cells was mixed with a DAL in a glass tube, heated at 37 or 42 Β°C for 30 min in a water bath, and cultured at 37 Β°C for 20 or 72 h. Cell viability was measured by the mitochondrial dehydrogenase- based WST-1 assay. DALs incorporated into EAT cells was extracted and measured by gas-liquid chromatography. Results: The reduction of cell viability by DALs was markedly enhanced upon the treatment at 42 Β°C compared to that at 37 oC. At 37 oC, delta-hexadecalactone (DH16 : 0) and delta-tetradecalactone (DTe14 : 0) displayed cytostatic activity (at 100 Β΅M survival level: 20.7%, 66.1%; at 50 Β΅M β 41.2%, 82.4%, respectively). Their activity was more marked at 42 Β°C (at 100 Β΅M 10.6%, 27.6%; at 50 Β΅M 30.6, 37.5 %, ibid). The other DALs, delta-undecalactone (DU11 : 0), delta-dodecalactone (DD12 : 0), and delta-tridecanolactone (DTr13 : 0) were almost ineffective. Evaluation of survival rate in the cells treated for 30 min by DALs with the next culturing of EAT cells for 72 h resulted in the enhanced carcinostatic activity of DH16:0 and DTe14:0 even at concentrations as low as 25 Β΅M at either 37 Β°C (18.5%, 78.5%, ibid) or 42 Β°C (5.0%, 42.0%, ibid), but the others exhibited slight activity or none. DH16 : 0 was effective at either 37 Β°C (36.0%) or 42 Β°C (23.0%) even at a lower dose of 10 Β΅M. At the same time only the most cytostatic DH16 : 0 was incorporated into EAT cells and the rate of incorporation was more at 42 Β°C than at 37 Β°C. Conclusion: Delta-hexadecanolactone (DH16 : 0) exhibited the most cytostatic effect that was significantly enhanced by hyperthermia. It allows to consider it as a potent antitumor agent, especially in combination with hyperthermia.Π¦Π΅Π»Ρ: ΠΎΡΠ΅Π½ΠΈΡΡ ΠΏΡΠΎΠΌΠΎΡΠΎΡΠ½ΡΠΉ ΡΡΡΠ΅ΠΊΡ Π³ΠΈΠΏΠ΅ΡΡΠ΅ΡΠΌΠΈΠΈ Π½Π° ΠΏΡΠΎΡΠΈΠ²ΠΎΠΎΠΏΡΡ
ΠΎΠ»Π΅Π²ΡΡ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ Π½ΠΎΠ²ΡΡ
Π½ΠΈΠ·ΠΊΠΎΠΌΠΎΠ»Π΅ΠΊΡΠ»ΡΡΠ½ΡΡ
(184β254 ΠΠ°)
Π΄Π΅Π»ΡΡΠ°-Π°Π»ΠΊΠΈΠ»Π»Π°ΠΊΡΠΎΠ½ΠΎΠ² (DALs), Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈ ΡΠΈΠ½ΡΠ΅Π·ΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΠΈΠ· ΡΠ°Π·Π½ΡΡ
ΠΌΠ°ΠΊΡΠΎΡΠΈΠΊΠ»ΠΈΡΠ΅ΡΠΊΠΈΡ
Π²ΡΡΠΎΠΊΠΎΠΌΠΎΠ»Π΅ΠΊΡΠ»ΡΡΠ½ΡΡ
(348β439ΠΠ°)
Π»Π°ΠΊΡΠΎΠ½ΠΎΠ² Π΅ΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎΠ³ΠΎ ΠΏΡΠΎΠΈΡΡ
ΠΎΠΆΠ΄Π΅Π½ΠΈΡ, ΡΠ°ΠΊΠΈΡ
ΠΊΠ°ΠΊ ΠΊΠ°ΠΌΠΏΡΠΎΡΠ΅ΡΠΈΠ½ ΠΈ ΡΠ°Π»ΡΡΠΈΠ΅ΡΠΈΠ½. ΠΠ΅ΡΠΎΠ΄Ρ: ΡΡΡΠΏΠ΅Π½Π·ΠΈΡ ΠΊΠ»Π΅ΡΠΎΠΊ Π°ΡΡΠΈΡΠ½ΠΎΠΉ ΠΎΠΏΡΡ
ΠΎΠ»ΠΈ
ΠΡΠ»ΠΈΡ
Π° (EAT) ΡΠΌΠ΅ΡΠΈΠ²Π°Π»ΠΈ Ρ DAL Π² ΡΡΠ΅ΠΊΠ»ΡΠ½Π½ΠΎΠΉ ΠΏΡΠΎΠ±ΠΈΡΠΊΠ΅, Π½Π°Π³ΡΠ΅Π²Π°Π»ΠΈ Π΄ΠΎ 37 Β°C ΠΈΠ»ΠΈ 42 Β°C Π² ΡΠ΅ΡΠ΅Π½ΠΈΠ΅ 30 ΠΌΠΈΠ½ Π½Π° Π²ΠΎΠ΄ΡΠ½ΠΎΠΉ Π±Π°Π½Π΅
ΠΈ Π΄Π°Π»Π΅Π΅ ΠΊΡΠ»ΡΡΠΈΠ²ΠΈΡΠΎΠ²Π°Π»ΠΈ ΠΏΡΠΈ 37 Β°C Π² ΡΠ΅ΡΠ΅Π½ΠΈΠ΅ 20 ΠΈΠ»ΠΈ 72 Ρ. ΠΡΠ΅Π½ΠΊΡ ΠΆΠΈΠ·Π½Π΅ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΠΈ ΠΊΠ»Π΅ΡΠΎΠΊ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΠΈ Ρ ΠΏΠΎΠΌΠΎΡΡΡ WST-1
Π°Π½Π°Π»ΠΈΠ·Π°, ΠΎΡΠ½ΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ Π½Π° ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠΈ ΠΌΠΈΡΠΎΡ
ΠΎΠ½Π΄ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ Π΄Π΅Π³ΠΈΠ΄ΡΠΎΠ³Π΅Π½Π°Π·Ρ. ΠΠ½ΠΊΠΎΡΠΏΠΎΡΠΈΡΠΎΠ²Π°Π½Π½ΡΠ΅ Π² EAT-ΠΊΠ»Π΅ΡΠΊΠΈ DALs ΡΠΊΡΡΡΠ°Π³ΠΈΡΠΎΠ²Π°Π»ΠΈ,
ΠΈΡ
ΡΡΠΎΠ²Π΅Π½Ρ ΠΈΠ·ΠΌΠ΅ΡΡΠ»ΠΈ Ρ ΠΏΠΎΠΌΠΎΡΡΡ Π³Π°Π·ΠΎ-ΠΆΠΈΠ΄ΠΊΠΎΡΡΠ½ΠΎΠΉ Ρ
ΡΠΎΠΌΠ°ΡΠΎΠ³ΡΠ°ΡΠΈΠΈ. Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ: DALs Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎ ΡΠ½ΠΈΠΆΠ°Π»ΠΈ
ΠΆΠΈΠ·Π½Π΅ΡΠΏΠΎΡΠΎΠ±Π½ΠΎΡΡΡ ΠΊΠ»Π΅ΡΠΎΠΊ ΠΏΠΎΡΠ»Π΅ ΠΏΡΠ΅Π΄Π²Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠΉ ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠΈ ΠΏΡΠΈ 42 Β°C ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Ρ 37 Β°C. ΠΡΠΈ 37 Β°C Π±ΡΠ»ΠΈ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΠΌΠΈ
Π΄Π΅Π»ΡΡΠ°-Π³Π΅ΠΊΡΠ°Π΄Π΅ΠΊΠ°Π»Π°ΠΊΡΠΎΠ½ (DH16 : 0) ΠΈ Π΄Π΅Π»ΡΡΠ°-ΡΠ΅ΡΡΠ°Π΄Π΅ΠΊΠ°Π»Π°ΠΊΡΠΎΠ½ (DTe14 : 0) (ΠΏΡΠΈ 100 ΞΌM ΡΡΠΎΠ²Π΅Π½Ρ Π²ΡΠΆΠΈΠ²Π°Π΅ΠΌΠΎΡΡΠΈ: 20,7; 66,1%;
ΠΏΡΠΈ 50 ΞΌM β 41,2; 82,4% ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ). ΠΡΠΎΡ ΡΡΡΠ΅ΠΊΡ Π±ΡΠ» Π±ΠΎΠ»Π΅Π΅ Π²ΡΡΠ°ΠΆΠ΅Π½Π½ΡΠΌ ΠΏΡΠΈ 42 Β°C (ΠΏΡΠΈ 100 ΞΌM 10,6; 27,6%; ΠΏΡΠΈ
50ΞΌM 30,6; 37,5% ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ). ΠΡΡΠ³ΠΈΠ΅ DALs, Π° ΠΈΠΌΠ΅Π½Π½ΠΎ Π΄Π΅Π»ΡΡΠ°-ΡΠ½Π΄Π΅ΠΊΠ°Π»Π°ΠΊΡΠΎΠ½ (DU11 : 0), Π΄Π΅Π»ΡΡΠ°-Π΄ΠΎΠ΄Π΅ΠΊΠ°Π»Π°ΠΊΡΠΎΠ½ (DD12 : 0)
ΠΈ Π΄Π΅Π»ΡΡΠ°-ΡΡΠΈΠ΄Π΅ΠΊΠ°Π»Π°ΠΊΡΠΎΠ½ (DTr13 : 0) Π±ΡΠ»ΠΈ ΠΏΡΠ°ΠΊΡΠΈΡΠ΅ΡΠΊΠΈ Π½Π΅ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½Ρ. ΠΡΠ΅Π½ΠΊΠ° ΡΡΠΎΠ²Π½Ρ Π²ΡΠΆΠΈΠ²Π°Π΅ΠΌΠΎΡΡΠΈ EAT-ΠΊΠ»Π΅ΡΠΎΠΊ, 30 ΠΌΠΈΠ½
ΠΎΠ±ΡΠ°Π±ΠΎΡΠ°Π½Π½ΡΡ
DALs Ρ ΠΏΠΎΡΠ»Π΅Π΄ΡΡΡΠΈΠΌ ΠΊΡΠ»ΡΡΠΈΠ²ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ Π² ΡΠ΅ΡΠ΅Π½ΠΈΠ΅ 72 Ρ, ΠΏΠΎΠΊΠ°Π·Π°Π»Π° ΠΏΠΎΠ²ΡΡΠ΅Π½Π½ΡΡ ΠΊΠ°Π½ΡΠ΅ΡΠΎΡΡΠ°ΡΠΈΡΡΠ΅ΠΊΡΡ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ
DH16 : 0 ΠΈ DTe14 :0 Π΄Π°ΠΆΠ΅ ΠΏΡΠΈ 25 ΞΌM ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΈ, ΠΊΠ°ΠΊ ΠΏΡΠΈ 37 Β°C (18,5; 78,5% ΡΠΎΠΎΡΠ²Π΅ΡΡΠ²Π΅Π½Π½ΠΎ), ΡΠ°ΠΊ ΠΈ ΠΏΡΠΈ 42 Β°C (5,0; 42,0%
ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ). ΠΠ»Ρ Π΄ΡΡΠ³ΠΈΡ
DALs Π΄Π°Π½Π½ΡΠΉ ΡΡΡΠ΅ΠΊΡ Π±ΡΠ» Π½Π΅Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΡΠΉ Π»ΠΈΠ±ΠΎ ΠΎΡΡΡΡΡΡΠ²ΠΎΠ²Π°Π». DH16 : 0 ΠΎΡΡΠ°Π²Π°Π»ΡΡ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΠΌ
ΠΊΠ°ΠΊ ΠΏΡΠΈ 37 Β°C (36,0%), ΡΠ°ΠΊ ΠΈ ΠΏΡΠΈ 42 Β°C (23,0%) Π² 10 ΞΌM ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΈ. Π ΡΠΎ ΠΆΠ΅ Π²ΡΠ΅ΠΌΡ ΡΠΎΠ»ΡΠΊΠΎ Π½Π°ΠΈΠ±ΠΎΠ»Π΅Π΅ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΠΉ
DAL β DH16 : 0 ΠΈΠ½ΠΊΠΎΡΠΏΠΎΡΠΈΡΠΎΠ²Π°Π»ΡΡ Π² ΠΊΠ»Π΅ΡΠΊΠΈ EAT, ΠΈ ΡΡΠΎΠ²Π΅Π½Ρ ΠΈΠ½ΠΊΠΎΡΠΏΠΎΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π±ΡΠ» Π²ΡΡΠ΅ ΠΏΡΠΈ 42 Β°C, ΡΠ΅ΠΌ ΠΏΡΠΈ 37 Β°C. ΠΡΠ²ΠΎΠ΄Ρ:
Π΄Π΅Π»ΡΡΠ°-Π³Π΅ΠΊΡΠ°Π΄Π΅ΠΊΠ°Π½ΠΎΠ»Π°ΠΊΡΠΎΠ½ (DH16 : 0) ΠΏΠΎΠΊΠ°Π·Π°Π» Π½Π°ΠΈΠ±ΠΎΠ»ΡΡΡΡ ΡΠΈΡΠΎΡΡΠ°ΡΠΈΡΠ΅ΡΠΊΡΡ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡ, ΠΊΠΎΡΠΎΡΠ°Ρ Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎ ΡΡΠΈΠ»ΠΈΠ²Π°Π»Π°ΡΡ
Π² ΠΊΠΎΠΌΠ±ΠΈΠ½Π°ΡΠΈΠΈ Ρ Π³ΠΈΠΏΠ΅ΡΡΠ΅ΡΠΌΠΈΠ΅ΠΉ. ΠΡΠΎΡ DAL ΠΌΠΎΠΆΠ½ΠΎ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡ ΠΊΠ°ΠΊ ΠΏΠΎΡΠ΅Π½ΡΠΈΠ°Π»ΡΠ½ΡΠΉ ΡΠΈΡΠΎΡΡΠ°ΡΠΈΠΊ, Π΄Π΅ΠΉΡΡΠ²ΠΈΠ΅ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΡΡΠΈΠ»ΠΈΠ²Π°Π΅ΡΡΡ
ΠΏΡΠΈ Π³ΠΈΠΏΠ΅ΡΡΠ΅ΡΠΌΠΈΠΈ
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