3,349 research outputs found
Non-standard Dirac adjoint spinor: The emergence of a new dual
In this present communication we provide a new derivation of the Dirac dual
structure by employing a different approach from the originally proposed.
Following a general and rigorous mathematical process to compute the dual
structure, we investigate if is possible to break the existing "rigidity" in
its primordial formulation. For this task, firstly, we look towards to
understand the core of the Dirac spinors construction and then, we suggest to
built an alternative dual structure for the Dirac spinor, which preserve an
invariant norm under any transformation. Finally, we verify
if the prominent physical contents are maintained or if it is affected by such
construction.Comment: 7 pages, 0 figure
Neural Controller for a Mobile Robot in a Nonstationary Enviornment
Recently it has been introduced a neural controller for a mobile robot that learns both forward and inverse odometry of a differential-drive robot through an unsupervised learning-by-doing cycle. This article introduces an obstacle avoidance module that is integrated into the neural controller. This module makes use of sensory information to determine at each instant a desired angle and distance that causes the robot to navigate around obstacles on the way to a final target. Obstacle avoidance is performed in a reactive manner by representing the objects and target in the robot's environment as Gaussian functions. However, the influence of the Gaussians is modulated dynamically on the basis of the robot's behavior in a way that avoids problems with local minima. The proposed module enables the robot to operate successfully with different obstacle configurations, such as corridors, mazes, doors and even concave obstacles.Air Force Office of Scientific Research (F49620-92-J-0499
Questing for Algebraic Mass Dimension One Spinor Fields
This work deals with new classes of spinors of mass dimension one in
Minkowski spacetime. In order to accomplish it, the Lounesto classification
scheme and the inversion theorem are going to be used. The algebraic framework
shall be revisited by explicating the central point performed by the Fierz
aggregate. Then the spinor classification is generalized in order to encompass
the new mass dimension one spinors. The spinor operator is shown to play a
prominent role to engender the new mass dimension one spinors, accordingly.Comment: 7 pages, final version to appear in Eur. Phys. J.
On the bilinear covariants associated to mass dimension one spinors
In this paper we approach the issue of Clifford algebra basis deformation,
allowing for bilinear covariants associated to Elko spinors which satisfy the
Fierz-Pauli-Kofink identities. We present a complete analysis of covariance,
taking into account the involved dual structure associated to Elko. Moreover,
the possible generalizations to the recently presented new dual structure are
performed.Comment: 9 pages, 0 figure
Discriminating among theories of spiral structure using Gaia DR2
We compare the distribution in position and velocity of nearby stars from the
Gaia DR2 radial velocity sample with predictions of current theories for
spirals in disc galaxies. Although the rich substructure in velocity space
contains the same information, we find it more revealing to reproject the data
into action-angle variables, and we describe why resonant scattering would be
more readily identifiable in these variables. We compute the predicted changes
to the phase space density, in multiple different projections, that would be
caused by a simplified isolated spiral pattern, finding widely differing
predictions from each theory. We conclude that the phase space structure
present in the Gaia data shares many of the qualitative features expected in
the transient spiral mode model. We argue that the popular picture of
apparently swing-amplified spirals results from the superposition of a few
underlying spiral modes.Comment: Revised version accepted to appear in MNRAS. Some significant
improvements. A full resolution version of Fig 4 is available from
http://www.physics.rutgers.edu/~sellwood/mult_res.pd
La comunicación interpersonal como modelo teórico de las comunicaciones humanas
Toda teoría se funda en la experiencia. Si entre las experiencias observadas existe una que sea la más frecuente, universal e importante, la teoría debe preferentemente fundarse en ella, como prototipo. Este principio nos guiará en el estudio de la comunicación interpersonal. El hombre aun antes de ser, necesita como condición previa la comunicación personal. La concepción misma es fruto de la más perfecta y completa comunicación interpersonal, la del padre y la de la madre: transmisión de genes por la compenetración de dos seres complementarios en un amor erótico, psíquico y social.
Si examinamos el comportamiento en el tiempo de la infancia, veremos que la comunicación interpersonal es la primera experiencia del hombre-feto dentro del útero materno; existe una comunicación envolvente y táctil durante nueve meses. La comunicación táctil es tierna, continua y transformadora en la etapa fetal y deja sello indeleble en la historia posterior del hombre y sólo cambian las formas táctiles con otras personas en la vida adulta.ITESO, A.C
Type-4 spinors: transmuting from Elko to single-helicity spinors
In this communication we briefly report an unexpected theoretical discovery
which emerge from the mapping of Elko mass-dimension-one spinors into single
helicity spinors. Such procedure unveils a class of spinor which is classified
as type-4 spinor field within Lounesto classification. In this paper we explore
the underlying physical and mathematical contents of the type-4 spinor.Comment: 9 pages, 0 figure
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