3,949 research outputs found
Introductions
An introduction to the Symposium and an introduction to Blockchain technology in preparation for the topics of the rest of the symposium
Periodic Ising Correlations
In this paper, we first rework B. Kaufman's 1949 paper, "Crystal Statistics.
II. Partition Function Evaluated by Spinor Analysis", by using representation
theory. Our approach leads to a simpler and more direct way of deriving the
spectrum of the transfer matrix for the finite periodic Ising model. We then
determine formulas for the spin correlation functions that depend on the matrix
elements of the induced rotation associated with the spin operator in a basis
of eigenvectors for the transfer matrix. The representation of the spin matrix
elements is obtained by considering the spin operator as an intertwining map.
We exhibit the "new" elements V+ and V- in the Bugrij-Lisovyy formula as part
of a holomorphic factorization of the periodic and anti-periodic summability
kernels on the spectral curve associated with the induced rotation for the
transfer matrix.Comment: 36 page
Mesoscopic effects in superconductor-ferromagnet-superconductor junctions
We show that at zero temperature the supercurrent through the superconductor
- ferromagnetic metal - superconductor junctions does not decay exponentially
with the thickness of the junction. At large it has a random
sample-specific sign which can change with a change in temperature. In the case
of mesoscopic junctions the phase of the order parameter in the ground state is
a random sample-specific quantity. In the case of junctions of large area the
ground state phase difference is .Comment: 4 pages, 1 figur
Origin of matter out of pure curvature
We propose a mechanism for origin of matter in the universe in the framework
of Einstein-Gauss-Bonnet gravity in higher dimensions. The recently discovered
new static black hole solution by the authors \cite{md2006} with the
Kaluza-Klein split up of spacetime as a product of the usual {\ma M}^4 with a
space of negative constant curvature is indeed a pure gravitational creation of
a black hole which is also endowed with a Maxwell-like {\it gravitational
charge} in four-dimensional vacuum spacetime. Further it could be envisioned as
being formed from anti-de Sitter spacetime by collapse of radially inflowing
charged null dust. It thus establishes the remarkable reciprocity between
matter and gravity - as matter produces gravity (curvature), gravity too
produces matter.Comment: 8 pages, 1 Fig, Received Honorable Mention in 2007 GRF Essay
Competition, Summary of the talk given at Himalayan Relativity Dialogue at
Mirik, April 18-20, 200
The experience of Southern European countries in the implementation of the policy of preservation of health
Analyzes the group of Southern European countries concerning the introduction of policies for the preservation of health. It is noted that health systems are reformed and developed in accordance with social changes and processes that occur in the health care system in the world is very dynamic and versatile.It refers to the importance of political decisions in the implementation of measures for the preservation of health. The main program of each country, their directions and features. Defined groups of countries with high and low levels of political consciousness in maintaining health. The conclusion is drawn on expediency of introduction of positive experience in politics for the preservation of health in Ukraine. Key words: politics, preservation of health, system health, a healthy lifestyle, preventive activities, the national program, the Beveridge modelАналізується група країн Південної Європи на предмет запровадження політики збереження здоров’я. Наголошується на тому, що системи охорони здоров’я реформуються та розвиваються відповідно до суспільних змін а процеси, які відбуваються у системі охорони здоров’я світу вельми динамічні та різнобічні. Вказується на важливості політичних рішень у реалізації заходів по збереженню здоров’я. Наведені основні прграми кожної країни, їх напрямки та особливості. Визначено групи країн з високим та низьким рівнем політичної свідомості у питаннях збереження здоров’я. Зроблено висновок про доцільність запровадження позитивного досвіду у політиці збереження здоров’я в Україні.Ключові слова: політика, збереження здоров’я, ситема охорони здоров’я, здоровий спосіб життя, профілактичні заходи, національна програма, модель БеверіджаАнализируется группа стран Южной Европы на предмет введения политики сохранения здоровья. Отмечается, что системы здравоохранения реформируются и развиваются в соответствии с общественными изменениями а процессы, которые происходят в системе здравоохранения мира весьма динамичны и разносторонние. Указывается на важность политических решений в реализации мероприятий по сохранению здоровья. Приведены основные программы каждой страны, их направления и особенности. Определены группы стран с высоким и низким уровнем политической сознательности в вопросах сохранения здоровья. Сделан вывод о целесообразности внедрения положительного опыта в политике сохранения здоровья в Украине. Ключевые слова: политика, сохранение здоровья, ситема здравоохранения, здоровый образ жизни, профилактические мероприятия, национальная программа, модель Бевериджаservation of health, system health, a healthy lifestyle, preventive activities, the national program, the Beveridge model
Characterisation and representation of non-dissipative electromagnetic medium with a double light cone
We study Maxwell's equations on a 4-manifold N with a medium that is
non-dissipative and has a linear and pointwise response. In this setting, the
medium can be represented by a suitable (2,2)-tensor on the 4-manifold N.
Moreover, in each cotangent space on N, the medium defines a Fresnel surface.
Essentially, the Fresnel surface is a tensorial analogue of the dispersion
equation that describes the response of the medium for signals in the geometric
optics limit. For example, in isotropic medium the Fresnel surface is at each
point a Lorentz light cone. In a recent paper, I. Lindell, A. Favaro and L.
Bergamin introduced a condition that constrains the polarisation for plane
waves. In this paper we show (under suitable assumptions) that a slight
strengthening of this condition gives a pointwise characterisation of all
medium tensors for which the Fresnel surface is the union of two distinct
Lorentz null cones. This is for example the behaviour of uniaxial medium like
calcite. Moreover, using the representation formulas from Lindell et al. we
obtain a closed form representation formula that pointwise parameterises all
medium tensors for which the Fresnel surface is the union of two distinct
Lorentz null cones. Both the characterisation and the representation formula
are tensorial and do not depend on local coordinates
Isolated, slowly evolving, and dynamical trapping horizons: geometry and mechanics from surface deformations
We study the geometry and dynamics of both isolated and dynamical trapping
horizons by considering the allowed variations of their foliating two-surfaces.
This provides a common framework that may be used to consider both their
possible evolutions and their deformations as well as derive the well-known
flux laws. Using this framework, we unify much of what is already known about
these objects as well as derive some new results. In particular we characterize
and study the "almost-isolated" trapping horizons known as slowly evolving
horizons. It is for these horizons that a dynamical first law holds and this is
analogous and closely related to the Hawking-Hartle formula for event horizons.Comment: 39 pages, 6 figures, version to appear in PRD : a few minor changes
and many typos corrected in equation
Phase coherent transport in SrTiO3/LaAlO3 interfaces
The two dimensional electron gas formed between the two band insulators
SrTiO3 and LaAlO3 exhibits a variety of interesting physical properties which
make it an appealing material for use in future spintronics and/or quantum
computing devices. For this kind of applications electrons have to retain their
phase memory for sufficiently long times or length. Using a mesoscopic size
device we were able to extract the phase coherence length, and its temperature
variation. We find the dephasing rate to have a power law dependence on
temperature. The power depends on the temperature range studied and sheet
resistance as expected from dephasing due to strong electron-electron
interactions.Comment: Submitted to Phys. Rev
Scratching the Bose surface
This is a `News and Views' article discussing recent proposals for ground
states of many boson systems which are neither superfluids nor Mott insulators.Comment: 4 pages, 1 figur
Ostrogradski approach for the Regge-Teitelboim type cosmology
We present an alternative geometric inspired derivation of the quantum
cosmology arising from a brane universe in the context of {\it geodetic
gravity}. We set up the Regge-Teitelboim model to describe our universe, and we
recover its original dynamics by thinking of such field theory as a
second-order derivative theory. We refer to an Ostrogradski Hamiltonian
formalism to prepare the system to its quantization. Our analysis highlights
the second-order derivative nature of the RT model and the inherited
geometrical aspect of the theory. A canonical transformation brings us to the
internal physical geometry of the theory and induces its quantization
straightforwardly. By using the Dirac canonical quantization method our
approach comprises the management of both first- and second-class constraints
where the counting of degrees of freedom follows accordingly. At the quantum
level our Wheeler-De Witt Wheeler equation agrees with previous results
recently found. On these lines, we also comment upon the compatibility of our
approach with the Hamiltonian approach proposed by Davidson and coworkers.Comment: 11 pages, 2 figures, accepted for publication in Phys. Rev.
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