962 research outputs found
Sliderule-like property of Wigner's little groups and cyclic S-matrices for multilayer optics
It is noted that two-by-two S-matrices in multilayer optics can be
represented by the Sp(2) group whose algebraic property is the same as the
group of Lorentz transformations applicable to two space-like and one time-like
dimensions. It is noted also that Wigner's little groups have a sliderule-like
property which allows us to perform multiplications by additions. It is shown
that these two mathematical properties lead to a cyclic representation of the
S-matrix for multilayer optics, as in the case of ABCD matrices for laser
cavities. It is therefore possible to write the N-layer S-matrix as a
multiplication of the N single-layer S-matrices resulting in the same
mathematical expression with one of the parameters multiplied by N. In
addition, it is noted, as in the case of lens optics, multilayer optics can
serve as an analogue computer for the contraction of Wigner's little groups for
internal space-time symmetries of relativistic particles.Comment: RevTex 13 pages, Secs. IV and V revised and expande
Iwasawa Effects in Multi-layer Optics
There are many two-by-two matrices in layer optics. It is shown that they can
be formulated in terms of a three-parameter group whose algebraic property is
the same as the group of Lorentz transformations in a space with two space-like
and one time-like dimensions, or the group which is a standard
theoretical tool in optics. Among the interesting mathematical properties of
this group, the Iwasawa decomposition drastically simplifies the matrix algebra
under certain conditions, and leads to a concise expression for the S-matrix
for transmitted and reflected rays. It is shown that the Iwasawa effect can be
observed in multi-layer optics, and a sample calculation of the S-matrix is
given.Comment: RevTex 10 pages including 1 psfi
Rotations associated with Lorentz boosts
It is possible to associate two angles with two successive non-collinear
Lorentz boosts. If one boost is applied after the initial boost, the result is
the final boost preceded by a rotation called the Wigner rotation. The other
rotation is associated with Wigner's O(3)-like little group. These two angles
are shown to be different. However, it is shown that the sum of these two
rotation angles is equal to the angle between the initial and final boosts.
This relation is studied for both low-speed and high-speed limits. Furthermore,
it is noted that the two-by-two matrices which are under the responsibility of
other branches of physics can be interpreted in terms of the transformations of
the Lorentz group, or vice versa. Classical ray optics is mentioned as a case
in point.Comment: LaTeX, 16 Pages, 4 epsfigure
Derecho y tecnología médica: orígenes de su legislación en Argentina
La evaluación de tecnología sanitaria, la difusión de las innovaciones y su transferencia, los factores que conllevan a una rápida aceptación de las mismas y el rol que cumple la tecnología en la sociedad delimitan el campo de los fenómenos ciencia, técnica y salud. Su reconocimiento en los sistemas jurídicos a través de la instauración de un proceso para la incorporación de las mismas dentro de las esferas del Estado, más precisamente, en sus sistemas sanitarios, cuenta con cuatro etapas, a saber, a) planificación, b) evaluación, c) adquisición y, d) gestión. En este trabajo, desarrollamos los orígenes del segundo y tercer proceso, lo que en doctrina internacional y las prácticas de los gobiernos se denomina “evaluación de tecnologías sanitarias e incorporación” de éstas a los sistemas de salud, ya que consideramos que estudiar estos fenómenos desde su perspectiva histórica y legal, coadyuvaría a un mejor desempeño de nuestros Estados en pos del bienestar general y las inversiones que se realicen al respecto, determinando qué órgano es el competente para realizarlo
The language of Einstein spoken by optical instruments
Einstein had to learn the mathematics of Lorentz transformations in order to
complete his covariant formulation of Maxwell's equations. The mathematics of
Lorentz transformations, called the Lorentz group, continues playing its
important role in optical sciences. It is the basic mathematical language for
coherent and squeezed states. It is noted that the six-parameter Lorentz group
can be represented by two-by-two matrices. Since the beam transfer matrices in
ray optics is largely based on two-by-two matrices or matrices, the
Lorentz group is bound to be the basic language for ray optics, including
polarization optics, interferometers, lens optics, multilayer optics, and the
Poincar\'e sphere. Because the group of Lorentz transformations and ray optics
are based on the same two-by-two matrix formalism, ray optics can perform
mathematical operations which correspond to transformations in special
relativity. It is shown, in particular, that one-lens optics provides a
mathematical basis for unifying the internal space-time symmetries of massive
and massless particles in the Lorentz-covariant world.Comment: LaTex 8 pages, presented at the 10th International Conference on
Quantum Optics (Minsk, Belarus, May-June 2004), to be published in the
proceeding
In situ generation of COx-free H2 by catalytic ammonia decomposition over Ru-Al-monoliths
Ru catalysts supported on alumina coated monoliths has been prepared employing three different precursor, which are ruthenium chloride, ruthenium nitrosyl nitrate and ruthenium acetyl acetonate, by an equilibrium adsorption method. The Ru particle sizes could be controlled varying the metal precursor salt. Among the prepared catalysts, Ru catalyst prepared from nytrosyl nitrate exhibited the highest activity which is concomitant to the largest mean Ru particle size of 3.5 nm. The values of the apparent activation energy calculated from the Arrhenius equation are according to the Temkin-Phyzev model, indicating that the recombinative desorption of N ad-atoms is the rate-determining step of the reaction. However, the ratio between the kinetic orders with respect to ammonia and hydrogen (-a/ß), is not in agreement to the valued predict by Temkin formalism. This fact could be related to the different operational conditions used during the reaction, and/or catalyst nature, but not to any change on the controlling step of the reaction
Fresnel coefficients as hyperbolic rotations
We describe the action of a plane interface between two semi-infinite media
in terms of a transfer matrix. We find a remarkably simple factorization of
this matrix, which enables us to express the Fresnel coefficients as a
hyperbolic rotation.Comment: 6 pages, 3 figure
Tecnología Médica y Derecho: La Potencialidad de la Ingeniería Biomédica
Si partimos del concepto básico, el Derecho no es otra cosa que la plasmación escrita de una realidad social, y como tal, esa realidad es cambiante. Si ratificamos –lo dicho por Nino– que el Derecho es como el aire porque está en todas partes, no queda duda alguna que la Tecnología Médica como tal no está exenta de regulaciones jurídica
Energy Self-Sufficiency Urban Module (ESSUM): GIS-LCA-based multi-criteria methodology to analyze the urban potential of solar energy generation and its environmental implications
The concentration of the population in cities has turned them into sources of environmental pollution, however, cities have a great potential for generating clean energy through renewable sources such as a responsible use of solar energy that reaches its rooftops. This work proposes a methodology to estimate the level of energy self-sufficiency in urban areas, particularly in a district of the city of Zaragoza (Spain). First, the Energy Self-Sufficiency Urban Module concept (ESSUM) is defined, then the self-sufficiency capacity of the city or district is determined using Geographical Information Systems (GIS), Light Detection and Ranging (LiDAR) point clouds and cadastral data. Secondly, the environmental implications of the implementation of these modules in the rooftops of the city using the LCA methodology are calculated. The results obtained show that total self-sufficiency of Domestic Hot Water (DHW) can be achieved using 21 % of available rooftop area, meanwhile the rest of rooftop area, dedicated to photovoltaic (PV), can reach 20 % of electricity self-sufficiency, supposing a final balance of a reduction in CO2 emissions of 12,695.4 t CO2eq/y and energy savings of 372,468.5 GJ/y. This corresponds to a scenario where full self-sufficiency of DHW was prioritized, with the remaining roof area dedicated to PV installation. In addition, other scenarios have been analyzed, such as the implementation of the energy systems separately
Optimizing omnidirectional reflection by multilayer mirrors
Periodic layered media can reflect strongly for all incident angles and
polarizations in a given frequency range. Quarter-wave stacks at normal
incidence are commonplace in the design of such omnidirectional reflectors. We
discuss alternative design criteria to optimize these systems.Comment: 9 pages, 6 figures. To be published in J. Opt. A: Pure and Applied
Optic
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