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1.
The four-point correlation function has been studied in Liouville field theory. If one of the fields is degenerate, such a
function is described in terms of Coulomb integrals. Some nontrivial relations for these integrals have been found that can
be used to obtain new exact results in conformal field theory. In particular, a four-point correlation function has been calculated
in minimal quantum gravity. The result agrees with the results obtained recently by different methods [A. A. Belavin and A.
B. Zamolodchikov, JETP Lett. 82, 7 (2005); Theor. Math. Phys. 147, 729 (2006); A. B. Zamolodchikov, Theor. Math. Phys. 142, 183 (2005); I. K. Kostov and V. B. Petkova, Theor. Math. Phys. 146, 108 (2006)].
The text was submitted by the authors in English. 相似文献
2.
Abstract The equation for the mean acoustic field has been obtained for a random turbulent medium using the Green function approach. The correlation function was described by the Karman distribution with the index n=2 approximately?11/6. Applying Bourret's approximation, the exact expression for the mass operator has been calculated analytically. The frequency dependence of the scattering coefficient of the mean field has been derived. Conditions of Cherenkov radiation are discussed. 相似文献
3.
Abstract A microminiature cryogenic diamond anvil cell (DAC) of overall dimensions ø10x24 mm made of nonmagnetic steel is described. A new principle allows to align anvils as perfectly as in traditional DACs. The microcell has been tested to 110 GPa. 相似文献
4.
Using the density functional theory the structural and magnetic properties of iron borate under high pressure have been studied.
At about P
= 22.7 GPa a first order phase transition to the phase described by the same space group R c has been found. The phase transition is accompanied by a 9% volume change of the unit cell, a four times decrease of the
magnetic moment on Fe, an increase of the charge density at Fe, and a disappearance of the energy gap in the electronic density
of states.
Received 21 September 2001 and Received in final form 6 January 2002 Published online 6 June 2002 相似文献
5.
Transverse and pseudo-transverse elastic waves have been studied in several scattering geometries in order to investigate
the temperature dependences of C
E
66
and C
E
14
over the range 300-1100 K, including the transitions near 860 K. These results complete those on C
E
44
we have obtained in a previous work. All these constants display discontinuities at the lock-in transition. In the phase, the results are analysed in term of lowest order couplings between strains ( e) and the order parameter ( Q). The main features are described by the lowest order biquadratic e2Q2 coupling, in particular for C
E
44
in a large temperature range. However, it appears that a contribution of the next coupling term arises for C
E
66
below K and that the first two lowest order terms have to be taken into account even just below the lock-in transition in the case
of C
E
14
. The temperature dependence of Q has been deduced and it can be well described in the framework of Landau's theory.
Received: 2 October 1997 / Received in final form: 3 December 1997 / Accepted: 29 January 1998 相似文献
6.
The vacuum ultraviolet absorption spectrum of Ca 2 has been extended down to 20?nm by using the same techniques as those described by Nzohabonayo et al. [2003, Molec. Phys., 101, 2917]. All the new states observed are Rydberg states giving three new ionization limits at 13.76?eV, 17.99?eV and a third one higher than 33?eV. 相似文献
7.
Small-angle scattering can produce significant effects when the Fermi surface is able to provide both electron and hole orbits
in a magnetic field. These orbits may run close to one another in k-space so that scattering through a small angle is sufficient to change the path of an electron radically. Simple models of
the phenomenon will be described and their calculated behaviour compared with experimental results.
This work has been published in Proc. Roy. Soc. A 305, 291 (1968). 相似文献
8.
We report on the synthesis, structural and electrical characterization of high quality Tl 2Ba 2Ca 1Cu 2O 8 (Tl-2212) superconducting films. The samples have been grown ex-situ on mm 2 LaAlO 3 (100) substrates by a combined approach of metal-organic chemical vapor deposition (MOCVD) and thallium vapor diffusion.
The morphological and compositional nature of the c-axis oriented films has been investigated by SEM and X-ray analyses. Typical values of K and MA/cm 2 at 77 K have been measured. Microwave measurements have been performed at f
= 87 GHz inserting the film in a copper cavity and at f
=1.5 GHz on patterned samples using a microstrip resonator technique. A penetration depth nm is evaluated by fitting the microwave data with phenomenological equations. The minimum value of the surface resistance
measured at 4.2 K is 60 and 6 m at 1.5 GHz and 87 GHz respectively. The microwave data are described in the context of a modified two fluid model. An evaluation
of the temperature dependence of the scattering rate has been performed through the simultaneous measurement of the surface
resistance and the penetration depth.
Received 16 December 1999 and Received in final form 17 March 2000 相似文献
9.
A new variety of P
4
W
10
O
38
, m
= 5 member of the monophosphate tungsten-bronze family with pentagonal tunnels ( MPTB
p), , has been isolated and studied by X-ray diffraction measurements. The structure has been solved by direct methods from single
crystal X-ray data. The monoclinic unit cell corresponds to a regular stacking of WO
3
-type slabs which are all five- WO
6
-octahedra thick and connected through PO
4
tetrahedra. This structure is comparable to that previously described for the MPTB
p'series with m
= 4 ( P
4
W
8
O
32
) and m
= 6 ( P
4
W
12
O
44
). An X-ray diffuse scattering investigation has revealed that this member is subjected to charge density wave instabilities
(CDW) located on chains running along the directions. Two CDW transitions have been observed at and , bearing some resemblance with those exhibited by the m
= 4 member. The corresponding modulation wave vectors can be accounted for by a hidden nesting mechanism which connects the crossing
points of differently oriented quasi-planar Fermi surfaces, as found for the low m (4 and 6) members of the MPTB's.
Received 12 March 1999 and received in final form 20 May 1999 相似文献
10.
Abstract An autoclave machined from a high strength titanium alloy for high pressure high resolution NMR studies is described. The autoclave has been used at pressures up to 600 MPa and temperatures between 150 K and 450 K. The molecular mobility of fluid n-butane has been studied by proton- and deuteron spin lattice relaxation time measurements of selectively deuterated butanes. Additional information about the dynamic is obtained from isotopic dilution experiments. The p, T dependence of the overall mobility and of the rotation of the methyl groups is derived from the data. 相似文献
11.
Abstract A series of studies on the partial X-ray diffuse scattering intensities from ternary alloys analysed through synchrotron radiation experiments has been reviewed. An intensity expression for the short-range order diffuse scattering has been developed, which is necessary in understanding the separation method of an observed X-ray diffuse intensity into partial intensities contributed from different origins. Techniques have been described in detail mainly concerning the Cu 2NiZn alloy, which have shown the benefits of the anomalous scattering effect of synchrotron radiation. The negative partial intensity maximum for the Cu-Ni pair found in the Cu-Ni-Zn alloy has been discussed from the viewpoints of crystallography and thermodynamics. In addition, at the end of the paper, local atomic arrangements causing the diffuse scatterings have been discussed. 相似文献
12.
Abstract The mechanism of detection of chemical vapors in air by an ionization chamber supplied by DC and AC voltage has been described. The theoretical explanation is based on numerical solutions of the differential equations of the cylindrical ionization chamber. The current of the ionization chamber operating in the AC regime has two components: a conductive component, caused by the ions drifts, and a capacitive component, caused by the distortion of the electric field. The ionization chamber operating in the DC regime has only the first component; hence the AC supplied chamber has larger response than the DC supplied chamber. 相似文献
13.
Abstract The dynamic viscosity η of the binary mixture tridecane + 2,2,4,4,6,8-heptamethyl-nonane has been measured in the temperature range 293.15-353.15K (in progressive 10 K steps) at pressures 0.1,20,40,60,80 and 100 MPa. The system is described by 9 molar fractions (0 to 1 in 0.125 progressive steps). The density ρ has been measured at pressures from 0.1 to 65 MPa in progressive 5 MPa steps. The whole set of experimental data represents 378 points for η and 882 for ρ. The measurements of η allow to determine the excess viscosity η E and the excess activation energy of viscous flow ΔG E versus pressure, temperature and composition. 相似文献
14.
We study frequency- and wave-vector dependent charge correlations in weakly doped antiferromagnets using Mori-Zwanzig projection
technique. The system is described by the two-dimensional t- J model. The ground state is expressed within a cumulant formalism which has been successfully applied to study magnetic properties
of the weakly doped system. Within this approach the ground state contains independent spin-bag quasiparticles (magnetic polarons).
We present results for the charge-density response function and for the optical conductivity at zero temperature for different
values of t
/
J. They agree well with numerical results calculated by exact diagonalization techniques. The density response function for
intermediate and large momenta shows a broad continuum on energy scales of order of several t whereas the optical conductivity for is dominated by low energy excitations (at 1.5-2 J). We show that these weak-doping properties can be well understood by transitions between excited states of spin-bag quasiparticles.
Received: 10 July 1997 / Revised: 19 March 1998 / Accepted: 3 April 1998 相似文献
15.
The design, synthesis, antinociceptive and β-adrenoceptor blocking activities of several eugenyloxy propanol azole derivatives have been described. In this synthesis, the reaction of eugenol with epichlorohydrin provided adducts 3 and 4 which were N-alkylated by diverse azoles to obtain the eugenyloxy propanol azole analogues in good yields. Adducts 3 and 4 were also reacted with azide ion to obtain the corresponding azide 6. The ‘Click’ Huisgen cycloaddition reaction of 6 with diverse alkynes afforded the title compounds in good yields. The synthesized eugenyloxy propanol azole derivatives were in vivo studied for the acute antinociception on male Spargue Dawley rats using tail-flick test. Compounds 5f, 5g, 7b and 11a exhibited potent analgesic properties in comparison with eugenol as a standard drug. In addition, all compounds were ex vivo tested for β-adrenoceptor blocking properties on isolated left atrium of male rats which exhibited partial antagonist or agonist behaviour compared to the standard drugs. The molecular docking study on the binding site of transient receptor potential vanilloid subtype 1 (TRPV1) has indicated that like capsaicin, eugenyloxy propanol azole analogues exhibited the strong affinity to bind at site of TPRV1 in a “tail-up, head-down” conformation and the presence of triazolyl moieties has played undeniable role in durable binding of these ligands to TRPV1. The in silico pharmacokinetic profile, drug likeness and toxicity predictions carried out for all compounds determined that 5g can be considered as potential antinociceptive drug candidate for future research.
相似文献
16.
Comment on Eur. Phys. J. B 27, 445 (2002)
We analyze the distribution of success of musicians, comparing a stretched exponential (found by J.A. Davies [Eur. Phys.
J. B 27, 445 (2002)]) with a distribution of the family of the q-exponential (presenting an intermediate power-law regime with a crossover to an exponential tail). We find that both assumptions
yield comparable results, within the available range of data, hence a definite conclusion cannot yet be taken. But this example
joins many others that has been found to be fairly described by q-exponentials (or variations of it), which may be indicative that there is a (significantly large) class of systems described
by nonextensive statistical mechanics, from where q-exponentials naturally appear.
Received 17 October 2002 Published online 31 December 2002 相似文献
17.
A study has been performed of the crystalline structure and optical characteristics of single crystals of gallium nitride
(GaN). The crystals were grown from a gallium-based flux. X-ray structural analysis showed that the crystals have wurzite
structure 2 H-GaN. From their luminescence characteristics and optical absorption spectra the crystals are similar to 2 H-GaN epitaxial layers described in the literature.
Fiz. Tverd. Tela (St. Petersburg) 39, 858–860 (May 1977) 相似文献
18.
A detailed investigation of the Fourier space of several Al-Pd-Mn samples with composition Al-72.6 at. %, Pd-22.9 at. %, Mn-4.5
at. % is reported. In the phase diagram of the Al-Pd-Mn ternary alloy, this composition corresponds to the so-called ξ' phase which was described as an icosahedral quasicrystalline approximant. By re-examining the Fourier space by means of
X-ray diffraction (powder patterns and single crystal precession patterns), complex structures in close relation with the
ξ'-phase have been observed. These long-range order complex structures are described as resulting from a periodic perturbation
of the ξ' structure along the c direction. Two states with periodicities c
(3 + τ) and c
(5 + τ) have been observed in this study ( τ: golden mean). Structural models based on periodic arrangements of “defects” layers separating layers of phase are proposed. These two states are certainly intermediate states between the phase and the metastable decagonal quasicrystalline phase.
Received 11 April 2002 / Received in final form 24 June 2002 Published online 17 September 2002 相似文献
19.
Conical refraction, which is due to the renormalization of the elastic moduli by the effective magnetoelastic interaction
and depends on the static magnetic field, has been experimentally observed in an α-Fe 2O 3 trigonal easy-plane antiferromagnet in addition to the usual internal conical refraction of transverse elastic waves propagating
along the trigonal C
3 axis. It has been shown that the deviation angle θ η of the energy flux from the C
3 axis at the internal conical refraction is independent of the magnetic field applied in the basal plane ( H ⊥ C
3) and is a constant determined by the ratio of the elastic moduli C
14 and C
44. The deviation angle of the energy flux at the antiferromagnetic conical refraction increases with the magnetic field and
approaches the value θ η at large H values. The results are well described by the theory of this phenomenon developed by E.A. Turov and confirm its basic conclusions. 相似文献
20.
Triple differential cross-section for K-shell ionization of medium-heavy atoms by relativistic electrons has been calculated for coplanar symmetric geometry. In
this calculation the final state is described by a non-relativistic wave function of Das and Seal [ Phys. Rev.
A47 (1993) 2978] multiplied with suitable spinors. Results of the present calculation are compared with the available experimental
data and with other theoretical calculations. 相似文献
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