134,271 research outputs found
The thermal conductivity of liquid hydrocarbons
Imperial Users onl
Polyploidization delay in rat hepatocytes under liver growth inhibition by hypokinesia
A study of young rats, weighing 55 to 59 g, after being for 10 days in conditions of limited mobility, shows a retardation of body growth as well as that of liver growth. The decrease in the rate of growth is accompanied by a reduction of cell proliferation and by delay polyploidization of hepatocytes in the liver of experimental rats. The materials, methods, and results of research are discussed
Understanding I=2 pi-pi Interaction
A correct understanding and description of the I=2 pi-pi S-wave interaction
is important for the extraction of the I=0 pi-pi S-wave interaction from
experimental data and for understanding the I=0 pi-pi S-wave interaction
theoretically. With t-channel rho, f2(1270) exchange and the pi pi -> rho rho
-> pi pi box diagram contribution, we reproduce the pi-pi isotensor S-wave and
D-wave scattering phase shifts and inelasticities up to 2.2 GeV quite well in a
K-matrix formalism.Comment: Talk given at Hadron 03: 10th International Conference on Hadron
Spectroscopy, Aschaffenburg, Germany, 31 Aug - 6 Sep 200
A Solvable Sequence Evolution Model and Genomic Correlations
We study a minimal model for genome evolution whose elementary processes are
single site mutation, duplication and deletion of sequence regions and
insertion of random segments. These processes are found to generate long-range
correlations in the composition of letters as long as the sequence length is
growing, i.e., the combined rates of duplications and insertions are higher
than the deletion rate. For constant sequence length, on the other hand, all
initial correlations decay exponentially. These results are obtained
analytically and by simulations. They are compared with the long-range
correlations observed in genomic DNA, and the implications for genome evolution
are discussed.Comment: 4 pages, 4 figure
Hamiltonian approach to the bound state problem in QCD_2
Bosonization of the two-dimensional QCD in the large N_C limit is performed
in the framework of Hamiltonian approach in the Coulomb gauge. The generalized
Bogoliubov transformation is applied to diagonalize the Hamiltonian in the
bosonic sector of the theory, and the composite operators creating/annihilating
bosons are obtained in terms of dressed quark operators. The bound state
equation is reconstructed as a result of the generalized Bogoliubov
transformation, and the form of its massless solution, chiral pion, is found
explicitly. Chiral properties of the theory are discussed.Comment: 9 pages, LaTeX2
Cosmological Perturbations in Non-Commutative Inflation
We compute the spectrum of cosmological perturbations in a scenario in which
inflation is driven by radiation in a non-commutative space-time. In this
scenario, the non-commutativity of space and time leads to a modified
dispersion relation for radiation with two branches, which allows for
inflation. The initial conditions for the cosmological fluctuations are
thermal. This is to be contrasted with the situation in models of inflation in
which the accelerated expansion of space is driven by the potential energy of a
scalar field, and in which the fluctuations are of quantum vacuum type. We find
that, in the limit that the expansion of space is almost exponential, the
spectrum of fluctuations is scale-invariant with a slight red tilt. The
magnitude of the tilt is different from what is obtained in a usual
inflationary model with the same expansion rate during the period of inflation.
The amplitude also differs, and can easily be adjusted to agree with
observations.Comment: 7 pages, 1 figur
Optical conductivity in multiferroic GaVS and GeVS: Phonons and electronic transitions
We report on optical spectroscopy on the lacunar spinels GaVS and
GeVS in the spectral range from 100 to 23000 cm and for
temperatures from 5 to 300 K. These multiferroic spinel systems reveal
Jahn-Teller driven ferroelectricity and complex magnetic order at low
temperatures. We study the infrared-active phonon modes and the low-lying
electronic excitations in the cubic high-temperature phase, as well as in the
orbitally and in the magnetically ordered low-temperature phases. We compare
the phonon modes in these two compounds, which undergo different
symmetry-lowering Jahn-Teller transitions into ferroelectric and orbitally
ordered phases, and exhibit different magnetic ground states. We follow the
splitting of the phonon modes at the structural phase transition and detect
additional splittings at the onset of antiferromagnetic order in GeVS.
We observe electronic transitions within the -derived bands of the V
clusters and document a significant influence of the structural and magnetic
phase transitions on the narrow electronic band gaps.Comment: 12 pages, 10 figure
Lifetime measurements of Triaxial Strongly Deformed bands in Tm
With the Doppler Shift Attenuation Method, quadrupole transition moments,
, were determined for the two recently proposed Triaxial Strongly Deformed
(TSD) bands in Tm. The measured moments indicate that the
deformation of these bands is larger than that of the yrast, signature
partners. However, the measured values are smaller than those predicted by
theory. This observation appears to be valid for TSD bands in several nuclei of
the regionComment: 8 pages, 5 figures. Submitted to Physical Review
Dynamical screening in strongly correlated metal SrVO3
The consequences of dynamical screening of Coulomb interaction among
correlated electrons in realistic materials have not been widely considered
before. In this letter we try to incorporate a frequency dependent Coulomb
interaction into the state-of-the-art ab initio electronic structure computing
framework of local density approximation plus dynamical mean-field theory, and
then choose SrVO3 as a prototype material to demonstrate the importance of
dynamical screening effect. It is shown to renormalise the spectral weight near
the Fermi level, to increase the effective mass, and to suppress the t2g
quasiparticle band width apparently. The calculated results are in accordance
with very recent angle-resolved photoemission spectroscopy experiments and Bose
factor ansatz calculations.Comment: 6 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1107.312
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