41 research outputs found
Generating Bounds for the Ground State Energy of the Infinite Quantum Lens Potential
Moment based methods have produced efficient multiscale quantization
algorithms for solving singular perturbation/strong coupling problems. One of
these, the Eigenvalue Moment Method (EMM), developed by Handy et al (Phys. Rev.
Lett.{\bf 55}, 931 (1985); ibid, {\bf 60}, 253 (1988b)), generates converging
lower and upper bounds to a specific discrete state energy, once the signature
property of the associated wavefunction is known. This method is particularly
effective for multidimensional, bosonic ground state problems, since the
corresponding wavefunction must be of uniform signature, and can be taken to be
positive. Despite this, the vast majority of problems studied have been on
unbounded domains. The important problem of an electron in an infinite quantum
lens potential defines a challenging extension of EMM to systems defined on a
compact domain. We investigate this here, and introduce novel modifications to
the conventional EMM formalism that facilitate its adaptability to the required
boundary conditions.Comment: Submitted to J. Phys.
Pointwise reconstruction of wave functions from their moments through weighted polynomial expansions: an alternative global-local quantization procedure
Many quantum systems admit an explicit analytic Fourier space expansion,
besides the usual analytic Schrodinger configuration space representation. We
argue that the use of weighted orthonormal polynomial expansions for the
physical states (generated through the power moments) can define both an
convergent, non-orthogonal, basis expansion with sufficient point-wise
convergent behaviors enabling the direct coupling of the global (power moments)
and local (Taylor series) expansions in configuration space. Our formulation is
elaborated within the orthogonal polynomial projection quantization (OPPQ)
configuration space representation previously developed by Handy and Vrinceanu.
The quantization approach pursued here defines an alternative strategy
emphasizing the relevance OPPQ to the reconstruction of the local structure of
the physical states
On the uniqueness of the surface sources of evoked potentials
The uniqueness of a surface density of sources localized inside a spatial
region and producing a given electric potential distribution in its
boundary is revisited. The situation in which is filled with various
metallic subregions, each one having a definite constant value for the electric
conductivity is considered. It is argued that the knowledge of the potential in
all fully determines the surface density of sources over a wide class of
surfaces supporting them. The class can be defined as a union of an arbitrary
but finite number of open or closed surfaces. The only restriction upon them is
that no one of the closed surfaces contains inside it another (nesting) of the
closed or open surfaces.Comment: 16 pages, 5 figure
Educação, conflito e convivência democrática
Após uma caracterização sucinta da actual condição pós-moderna, serão desenvolvidas
algumas questões que, pela sua relevância actual no campo da educação,
merecem ser revisitadas de modo crítico, nomeadamente, e num primeiro momento,
a escola, o conflito e a convivência. Num segundo momento, apontar-se-ão algumas
características da escola que fazem dela uma organização com alguma perversidade,
hipocrisia e irracionalidade. O último aspecto a ser tratado irá compreender
a escola como organização comunicacional ou organização convivencial, onde os
conceitos de disciplina, violência, conflito e convivência assumem um sentido mais
profundamente democrático.After a succinct characterization of the current postmodern condition, some
questions might be developed, because of its current relevance in the education
field, they must to be reviewed in a critical way, namely, and firstly, the school, the
conflict and the conviviality. Secondly, this article underlines some school’s
characteristics that turns it into an organization with a little perversity, hypocrisy
and irrationality. The last aspect to be treated is the understanding of the school as
a communicative or convivial organization, in which the concepts of discipline,
violence, conflict and conviviality assume a more democratic orientation.Enseguida a una caracterización sucinta de la actual condición pos-moderna,
serán desarrolladas algunas cuestiones que, por su relevancia actual en el campo
de la educación, merecen ser visitadas de modo crítico, nombradamente, y en
primero momento, la escuela, el conflicto y la convivencia. En segundo momento,
se apuntarán algunas características de la escuela que la hacen una organización
con alguna perversidad, hipocresía e irracionalidad. El último aspecto a ser tratado irá comprender la escuela como organización de comunicación u
organización de convivencia, donde los conceptos de disciplina, violencia,
conflicto e convivencia asumen un sentido más profundamente democrático.(undefined
Genetic Data Suggest Multiple Introductions of the Lionfish (Pterois miles) into the Mediterranean Sea
Widespread reports over the last six years confirm the establishment of lionfish (Pterois miles) populations in the eastern Mediterranean. Accumulated knowledge on lionfish invasions in the western Atlantic Ocean has shown that it is a successful invader and can have negative impacts on native species, indirect ecological repercussions and economic effects on local human societies. Here we analysed genetic sequences of lionfish from Cyprus as well as data from the whole distribution of the species, targeting the mtDNA markers cytochrome c oxidase subunit 1 (COI) and the control region (CR). Our results reflect a pattern of repeated introductions into the Mediterranean from the northern Red Sea and a secondary spread of this species west to Rhodes and Sicily. Presented results agree with previously published studies highlighting the genetic similarity with individuals from the northern Red Sea. Nevertheless, some individuals from Cyprus, in addition to those coming via the Suez Canal, were genetically similar to fish from the Indian Ocean, indicating genetic homogeneity among populations of P. miles across its current distribution, possibly facilitated by the ornamental fish trade and/or transport through ballast water.</jats:p
The Implications of Freeway Siting in California: Four Case Studies on the Effects of Freeways on Neighborhoods of Color
65A0674, TO 039California\u2019s freeways have come under increasing scrutiny for their disproportionately adverse impacts on low-income populations and populations of color. This study uses empirical research to not only understand but also quantify and describe in detail the historical impacts of freeways on communities of color in four California cities and areas: Pasadena, Pacoima, Sacramento, and San Jos\ue9. In these neighborhoods, freeways displaced many residents, significantly harmed those that remained, and left communities divided and depleted. The four cases differ in notable ways, but they share a disproportionate impact of freeway construction on communities of color. In Pasadena and Pacoima, decision-makers chose routes that displaced a greater share of households of color than proposed alternatives
Orthonormal polynomial projection quantization: an algebraic eigenenergy bounding method
The ability to generate tight eigenenergy bounds for low dimension bosonic or ferminonic, hermitian or non-hermitian, Schrödinger operator problems is an important objective in the computation of quantum systems. Very few methods can simultaneously generate lower and upper bounds. One of these is the Eigenvalue Moment Method (EMM) originally introduced by Handy and Besssis, exploiting the use of semidefinite programming/nonlinear-convex optimization (SDP) techniques as applied to the positivity properties of the multidimensional bosonic ground state for a large class of important physical systems (i.e. those admitting a moments’ representation). A recent breakthrough has been achieved through another, simpler, moment representation based quantization formalism, the Orthonormal Polynomial Projection Quantization Bounding Method (OPPQ-BM). It is purely algebraic and does not require any SDP analysis. We discuss its essential structure in the context of several one dimensional examples