997 research outputs found
Ordinary reduction of K3 surfaces
Let X be a K3 surface over a number field K. We prove that there exists a
finite algebraic field extension L/K such that X has ordinary reduction at
every non-archimedean place of L outside a density zero set of places.Comment: 7 page
A New Limit on the Antiproton Lifetime
Measurements of the cosmic ray pbar/p ratio are compared to predictions from
an inhomogeneous disk-diffusion model of pbar production and propagation within
the Galaxy, combined with a calculation of the modulation of the interstellar
cosmic ray spectra as the particles propagate through the heliosphere to the
Earth. The predictions agree with the observed pbar/p spectrum. Adding a finite
pbar lifetime to the model, we obtain the limit tau_pbar > 0.8 Myr (90 % C.L.).Comment: 13 pages, 3 encapsulated Postscript figures, uses AASTeX; accepted by
Astrophysical Journal; minor change
Optical properties of small polarons from dynamical mean-field theory
The optical properties of polarons are studied in the framework of the
Holstein model by applying the dynamical mean-field theory. This approach
allows to enlighten important quantitative and qualitative deviations from the
limiting treatments of small polaron theory, that should be considered when
interpreting experimental data. In the antiadiabatic regime, accounting on the
same footing for a finite phonon frequency and a finite electron bandwidth
allows to address the evolution of the optical absorption away from the
well-understood molecular limit. It is shown that the width of the multiphonon
peaks in the optical spectra depends on the temperature and on the frequency in
a way that contradicts the commonly accepted results, most notably in the
strong coupling case. In the adiabatic regime, on the other hand, the present
method allows to identify a wide range of parameters of experimental interest,
where the electron bandwidth is comparable or larger than the broadening of the
Franck-Condon line, leading to a strong modification of both the position and
the shape of the polaronic absorption. An analytical expression is derived in
the limit of vanishing broadening, which improves over the existing formulas
and whose validity extends to any finite-dimensional lattice. In the same
adiabatic regime, at intermediate values of the interaction strength, the
optical absorption exhibits a characteristic reentrant behavior, with the
emergence of sharp features upon increasing the temperature -- polaron
interband transitions -- which are peculiar of the polaron crossover, and for
which analytical expressions are provided.Comment: 16 pages, 6 figure
Endomorphisms of abelian varieties, cyclotomic extensions and Lie algebras
We prove an analogue of the Tate conjecture on homomorphisms of abelian
varieties over infinite cyclotomic extensions of finitely generated fields of
characteristic zero.Comment: 9 page
Towards Personalized Prostate Cancer Therapy Using Delta-Reachability Analysis
Recent clinical studies suggest that the efficacy of hormone therapy for
prostate cancer depends on the characteristics of individual patients. In this
paper, we develop a computational framework for identifying patient-specific
androgen ablation therapy schedules for postponing the potential cancer
relapse. We model the population dynamics of heterogeneous prostate cancer
cells in response to androgen suppression as a nonlinear hybrid automaton. We
estimate personalized kinetic parameters to characterize patients and employ
-reachability analysis to predict patient-specific therapeutic
strategies. The results show that our methods are promising and may lead to a
prognostic tool for personalized cancer therapy.Comment: HSCC 201
Diffusion and Transport Coefficients in Synthetic Opals
Opals are structures composed of the closed packing of spheres in the size
range of nano-to-micro meter. They are sintered to create small necks at the
points of contact. We have solved the diffusion problem in such structures. The
relation between the diffusion coefficient and the termal and electrical
conductivity makes possible to estimate the transport coefficients of opal
structures. We estimate this changes as function of the neck size and the
mean-free path of the carriers. The theory presented is also applicable to the
diffusion problem in other periodic structures.Comment: Submitted to PR
The behavior limestone under explosive load
Limestone behavior under explosive loading was investigated. The behavior of the limestone by the action of the three types of explosives, including granular, ammonite and emulsion explosives was studied in detail. The shape and diameter of the explosion craters were obtained. The observed fragments after the blast have been classified as large, medium and small fragments. Three full-scale experiments were carried out. The research results can be used as a qualitative test for the approbation of numerical methods
Logarithmic Moduli Spaces for Surfaces of Class VII
In this paper we describe logarithmic moduli spaces of pairs (S,D) consisting
of minimal surfaces S of class VII with positive second Betti number b_2
together with reduced divisors D of b_2 rational curves. The special case of
Enoki surfaces has already been considered by Dloussky and Kohler. We use
normal forms for the action of the fundamental group of the complement of D and
for the associated holomorphic contraction germ from (C^2,0) to (C^2,0).Comment: Minor correction of the dimension of the moduli spac
Adsorption refinement of waste transformer oil using industrial montmorillonite-containing sorbents
The possibilities of adsorption contact refining of waste transformer oil with active montmorillonite-containing sorbents of «Filtrol» series of BASF Catalysts LLC corporation and Zikeevsk М-80 deposit sorbent have been investigated. Usage of F-160 sorbents of «Filtrol» series in the refinement process allows achieving high quality degree of lean transformer oil, permitting its further use in the equipment with operating voltage to 750 kV
Metallic Xenon, Molecular Condensates, and Superconductivity
A possibility of explaining the light absorption observed to occur under
pressure-induced xenon metallization as due to the transition to the
superconducting state is analyzed. The mechanism of the van der Waals bonding
is discussed.Comment: LaTeX 2.09 (RevTeX), 4 pages, 4 PostScript figures included in tex
- …