1,064 research outputs found
Ballistic Localization in Quasi-1D Waveguides with Rough Surfaces
Structure of eigenstates in a periodic quasi-1D waveguide with a rough
surface is studied both analytically and numerically. We have found a large
number of "regular" eigenstates for any high energy. They result in a very slow
convergence to the classical limit in which the eigenstates are expected to be
completely ergodic. As a consequence, localization properties of eigenstates
originated from unperturbed transverse channels with low indexes, are strongly
localized (delocalized) in the momentum (coordinate) representation. These
eigenstates were found to have a quite unexpeted form that manifests a kind of
"repulsion" from the rough surface. Our results indicate that standard
statistical approaches for ballistic localization in such waveguides seem to be
unappropriate.Comment: 5 pages, 4 figure
Vapor swellable colloidal photonic crystals with pressure tunability
Polyferrocenylsilane gel photonic crystals have been reversibly swollen using solvent vapors, and exhibit precise pressure tunability over a wavelength range of greater than 100 nmGeneralitat Valenciana CTDIA/2002/2
An infinite family of magnetized Morgan-Morgan relativistic thin disks
Applying the Horsk\'y-Mitskievitch conjecture to the empty space solutions of
Morgan and Morgan due to the gravitational field of a finite disk, we have
obtained the corresponding solutions of the Einstein-Maxwell equations. The
resulting expressions are simply written in terms of oblate spheroidal
coordinates and the solutions represent fields due to magnetized static thin
disk of finite extension. Now, although the solutions are not asymptotically
flat, the masses of the disks are finite and the energy-momentum tensor agrees
with the energy conditions. Furthermore, the magnetic field and the circular
velocity show an acceptable physical behavior.Comment: Submitted to IJTP. This paper is a revised and extended version of a
paper that was presented at arXiv:1006.203
La antigua Roma y la AntigĂŒedad clĂĄsica en "El sitio de Krishnapur" de J.G. Farrell: unas notas
The aim of this paper is to analyze the references about the History of ancient Rome, in particular, and about the Classical Antiquity; that are present in the most famous novel by British writer J. G. Farrell (1935â1979): âThe Siege of Krishnapurâ which, along with his works ÊșTroublesÊș (1970) and âThe
Singapore Gripâ (1978); composed his famous trilogy about the decline of the British Empire and the political and social consequences that this entailed. This trilogy has been greatly praised by critics and readers around the world.El objetivo de este trabajo es analizar las referencias sobre la historia de la antigua Roma en particular, y la AntigĂŒedad clĂĄsica en general, presentes en la novela mĂĄs conocida del escritor britĂĄnico J.G. Farrell (1935â1979): âThe Siege of Krishnapurâ que, junto con sus obras âTroublesâ (1970) y âThe Singapore Gripâ (1978) componen su conocida trilogĂa sobre la decadencia del Imperio BritĂĄnico y las consecuencias polĂticas y sociales que este hecho acarreĂł. Esta trilogĂa ha sido enormemente alabada por crĂtica y lectores en todo el mundo
Development of a stress-induced martensitic transformation criterion for a Cu-Al-Be polycrystalline shape memory alloy undergoing uniaxial tension
This study presents a criterion for predicting the martensitic variants (MVs) that appear during the stress-induced martensitic transformation (SIMT) in a polycrystalline sample of Cu 11.5% wt. Al 0.5% wt. Be under simple tension. Our criterion is based on crystallographic parameters, such as the crystal orientation and Schmid factor (SF). The displacement vector fields (DVFs) were obtained in the observation system by a mathematical model and were used to distort the boundary of a set of grains. From the DVF, the strain tensor for each grain was obtained, and the strain ratio (SR) in the observation system was calculated. Electron backscattering diffraction (EBSD) measurements were performed to determine the crystal orientation of the grains. The inverse SF was used to determine the in-plane stress transformation diagrams (STDs) for each studied grain. The combination of a balance criterion (BC) and STD provided a criterion that allowed us to predict the possible order of stress-induced MVs formed as a function of the crystal orientation and thermomechanical parameters of the shape memory alloy (SMA) with higher accuracy than when using the criteria separately. To validate our criteria, we tested other researchers published results. Our results were in agreement and were capable of predicting the stress-induced MVs in a polycrystalline SMA.The authors wish to thank the Coordinacion de estudios de posgrado (CEP)-UNAM, PAPIIT project number TI 02414 and Instituto de Tecnologia de Materiales-UPV for financial support. The authors are grateful to the Electron Microscopy Service of the UPV and especially to Manuel Josep Planes Insausti and Jose Luis Moya Lopez. The authors are grateful to Martin Estrada Arcos, Alberto Higuera Garcia, and Antonio Gonzalez Montaiio for their technical support.GarcĂa Castillo, F.; CortĂ©s PĂ©rez, J.; AmigĂł BorrĂĄs, V.; SĂĄnchez ArĂ©valo, P.; Lara RodrĂguez, G. (2015). Development of a stress-induced martensitic transformation criterion for a Cu-Al-Be polycrystalline shape memory alloy undergoing uniaxial tension. Acta Materialia. 97:131-145. https://doi.org/10.1016/j.actamat.2015.06.044S1311459
Continuity of Genetic Risk for Aggressive Behavior Across the Life-Course
We test whether genetic influences that explain individual differences in aggression in early life also explain individual differences across the life-course. In two cohorts from The Netherlands (N = 13,471) and Australia (N = 5628), polygenic scores (PGSs) were computed based on a genome-wide meta-analysis of childhood/adolescence aggression. In a novel analytic approach, we ran a mixed effects model for each age (Netherlands: 12â70Â years, Australia: 16â73Â years), with observations at the focus age weighted as 1, and decaying weights for ages further away. We call this approach a ârolling weightsâ model. In The Netherlands, the estimated effect of the PGS was relatively similar from age 12 to age 41, and decreased from age 41â70. In Australia, there was a peak in the effect of the PGS around age 40Â years. These results are a first indication from a molecular genetics perspective that genetic influences on aggressive behavior that are expressed in childhood continue to play a role later in life
Theory of Stellar Oscillations
In recent years, astronomers have witnessed major progresses in the field of
stellar physics. This was made possible thanks to the combination of a solid
theoretical understanding of the phenomena of stellar pulsations and the
availability of a tremendous amount of exquisite space-based asteroseismic
data. In this context, this chapter reviews the basic theory of stellar
pulsations, considering small, adiabatic perturbations to a static, spherically
symmetric equilibrium. It starts with a brief discussion of the solar
oscillation spectrum, followed by the setting of the theoretical problem,
including the presentation of the equations of hydrodynamics, their
perturbation, and a discussion of the functional form of the solutions.
Emphasis is put on the physical properties of the different types of modes, in
particular acoustic (p-) and gravity (g-) modes and their propagation cavities.
The surface (f-) mode solutions are also discussed. While not attempting to be
comprehensive, it is hoped that the summary presented in this chapter addresses
the most important theoretical aspects that are required for a solid start in
stellar pulsations research.Comment: Lecture presented at the IVth Azores International Advanced School in
Space Sciences on "Asteroseismology and Exoplanets: Listening to the Stars
and Searching for New Worlds" (arXiv:1709.00645), which took place in Horta,
Azores Islands, Portugal in July 201
Revisiting cattle temperament in beef cow-calf systems: Insights from farmersâ perceptions about an autochthonous breed
Understanding temperament is an important part of cattle production since undesirable temperament may cause serious problems associated with aggression, maternal care, and human safety. However, little is known about how farmers define or assess temperament, especially in autochthonous cattle breeds. The aim of this study was to explore perceptions of farmers about the temperament of the Pyrenean cattle breed with special attention to beef cow-calf systems in Spain. The methodology used to obtain the information was focus group discussions (FGD). Farmers defined temperament as a behavioural response to challenging situations imposed by human handling. Specific terms used were related to active or passive reactions to fear (e.g., âstrongâ, âaggressiveâ, ânervousâ, âfearfulâ). The speed of response to stimuli was also important. Female temperament was thought to become more docile with age while bull temperament was more variable. Maternal aggressiveness was highlighted as a potential human safety problem, but also desirable in an extensively bred animal who may need to defend calves against predators. Anatomical characteristics were seen as unreliable predictors of temperament, while behavioural indicators were more widely used, such as âalertnessâ, which was a general trait of the breed, and âgazeâ, which, when associated with an alert expression, suggests a potential threat. Sensory acuity, such as sight and smell, were thought to be related with temperament in some FGDs but there was no overall agreement as to whether different behavioural responses were due to differences in sensory acuity. The results from the study could be useful during training programs or in the development of new genetic selection schemes and evaluation protocols involving cattle temperament
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