78 research outputs found
Canonical-type connection on almost contact manifolds with B-metric
The canonical-type connection on the almost contact manifolds with B-metric
is constructed. It is proved that its torsion is invariant with respect to a
subgroup of the general conformal transformations of the almost contact
B-metric structure. The basic classes of the considered manifolds are
characterized in terms of the torsion of the canonical-type connection.Comment: 11 pages, The final publication is available at
http://www.springerlink.co
Natural connection with totally skew-symmetric torsion on almost contact manifolds with B-metric
A natural connection with totally skew-symmetric torsion on almost contact
manifolds with B-metric is constructed. The class of these manifolds, where the
considered connection exists, is determined. Some curvature properties for this
connection, when the corresponding curvature tensor has the properties of the
curvature tensor for the Levi-Civita connection and the torsion tensor is
parallel, are obtained.Comment: 17 page
Timelike surfaces with zero mean curvature in Minkowski 4-space
On any timelike surface with zero mean curvature in the four-dimensional
Minkowski space we introduce special geometric (canonical) parameters and prove
that the Gauss curvature and the normal curvature of the surface satisfy a
system of two natural partial differential equations. Conversely, any two
solutions to this system determine a unique (up to a motion) timelike surface
with zero mean curvature so that the given parameters are canonical. We find
all timelike surfaces with zero mean curvature in the class of rotational
surfaces of Moore type. These examples give rise to a one-parameter family of
solutions to the system of natural partial differential equations describing
timelike surfaces with zero mean curvature.Comment: 15 page
Microscopic and macroscopic properties of A-superstatistics
The microscopic and the macroscopic properties of A-superstatistics, related
to the class A(0,n-1)\equiv sl(1|n) of simple Lie superalgebras are
investigated. The algebra sl(1|n) is described in terms of generators f_1^\pm,
>..., f_n^\pm, which satisfy certain triple relations and are called Jacobson
generators. The Fock spaces of A-superstatistics are investigated and the Pauli
principle of the corresponding statistics is formulated. Some thermal
properties of A-superstatistics are constructed under the assumption that the
particles interact only via statistical interaction imposed by the Pauli
principle. The grand partition function and the average number of particles are
written down explicitly in the general case and in two particular examples: 1)
the particles have one and the same energy and chemical potential; 2) the
energy spectrum of the orbitals is equidistant.Comment: 26 pages, 3 figure
A classification of the torsion tensors on almost contact manifolds with B-metric
The space of the torsion (0,3)-tensors of the linear connections on almost
contact manifolds with B-metric is decomposed in 15 orthogonal and invariant
subspaces with respect to the action of the structure group. Three known
connections, preserving the structure, are characterized regarding this
classification.Comment: 17 pages, exposition clarified, references adde
Algebraic structure of the Green's ansatz and its q-deformed analogue
The algebraic structure of the Green's ansatz is analyzed in such a way that
its generalization to the case of q-deformed para-Bose and para-Fermi operators
is becoming evident. To this end the underlying Lie (super)algebraic properties
of the parastatistics are essentially used.Comment: plain TeX, Preprint INRNE-TH-94/4, 13
The quantum superalgebra : deformed para-Bose operators and root of unity representations
We recall the relation between the Lie superalgebra and para-Bose
operators. The quantum superalgebra , defined as usual in terms
of its Chevalley generators, is shown to be isomorphic to an associative
algebra generated by so-called pre-oscillator operators satisfying a number of
relations. From these relations, and the analogue with the non-deformed case,
one can interpret these pre-oscillator operators as deformed para-Bose
operators. Some consequences for (Cartan-Weyl basis,
Poincar\'e-Birkhoff-Witt basis) and its Hopf subalgebra are
pointed out. Finally, using a realization in terms of ``-commuting''
-bosons, we construct an irreducible finite-dimensional unitary Fock
representation of and its decomposition in terms of
representations when is a root of unity.Comment: 15 pages, LaTeX (latex twice), no figure
Lectures on conformal field theory and Kac-Moody algebras
This is an introduction to the basic ideas and to a few further selected
topics in conformal quantum field theory and in the theory of Kac-Moody
algebras.Comment: 59 pages, LaTeX2e, extended version of lectures given at the Graduate
Course on Conformal Field Theory and Integrable Models (Budapest, August
1996), to appear in Springer Lecture Notes in Physic
Tamoxifen metabolism predicts drug concentrations and outcome in premenopausal patients with early breast cancer
Tamoxifen is the standard-of-care treatment for estrogen receptor-positive premenopausal breast cancer. We examined tamoxifen metabolism via blood metabolite concentrations and germline variations of CYP3A5, CYP2C9, CYP2C19 and CYP2D6 in 587 premenopausal patients (Asians, Middle Eastern Arabs, Caucasian-UK; median age 39 years) and clinical outcome in 306 patients. N-desmethyltamoxifen (DM-Tam)/(Z)-endoxifen and CYP2D6 phenotype significantly correlated across ethnicities (R2: 53%, P<10?77). CYP2C19 and CYP2C9 correlated with norendoxifen and (Z)-4-hydroxytamoxifen concentrations, respectively (P<0.001). DM-Tam was influenced by body mass index (P<0.001). Improved distant relapse-free survival (DRFS) was associated with decreasing DM-Tam/(Z)-endoxifen (P=0.036) and increasing CYP2D6 activity score (hazard ratio (HR)=0.62; 95% confidence interval (CI), 0.43–0.91; P=0.013). Low (<14?nM) compared with high (>35?nM) endoxifen concentrations were associated with shorter DRFS (univariate P=0.03; multivariate HR=1.94; 95% CI, 1.04–4.14; P=0.064). Our data indicate that endoxifen formation in premenopausal women depends on CYP2D6 irrespective of ethnicity. Low endoxifen concentration/formation and decreased CYP2D6 activity predict shorter DRFS
Fermi polaron-polaritons in charge-tunable atomically thin semiconductors
The dynamics of a mobile quantum impurity in a degenerate Fermi system is a fundamental problem in many-body physics. The interest in this field has been renewed due to recent ground-breaking experiments with ultracold Fermi gases. Optical creation of an exciton or a polariton in a two-dimensional electron system embedded in a microcavity constitutes a new frontier for this field due to an interplay between cavity coupling favouring ultralow-mass polariton formation6 and exciton–electron interactions leading to polaron or trion formation. Here, we present cavity spectroscopy of gate-tunable monolayer MoSe2 exhibiting strongly bound trion and polaron resonances, as well as non-perturbative coupling to a single microcavity mode. As the electron density is increased, the oscillator strength determined from the polariton splitting is gradually transferred from the higher-energy repulsive exciton-polaron resonance to the lower-energy attractive exciton-polaron state. Simultaneous observation of polariton formation in both attractive and repulsive branches indicates a new regime of polaron physics where the polariton impurity mass can be much smaller than that of the electrons. Our findings shed new light on optical response of semiconductors in the presence of free carriers by identifying the Fermi polaron nature of excitonic resonances and constitute a first step in investigation of a new class of degenerate Bose–Fermi mixtures.Physic
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