4,512 research outputs found
Symmetry properties of Penrose type tilings
The Penrose tiling is directly related to the atomic structure of certain
decagonal quasicrystals and, despite its aperiodicity, is highly symmetric. It
is known that the numbers 1, , , , ..., where
, are scaling factors of the Penrose tiling. We show that
the set of scaling factors is much larger, and for most of them the number of
the corresponding inflation centers is infinite.Comment: Paper submitted to Phil. Mag. (for Proceedings of Quasicrystals: The
Silver Jubilee, Tel Aviv, 14-19 October, 2007
Resonant Fibonacci Quantum Well Structures
We propose a resonant one-dimensional quasicrystal, namely, a multiple
quantum well (MQW) structure satisfying the Fibonacci-chain rule with the
golden ratio between the long and short inter-well distances. The resonant
Bragg condition is generalized from the periodic to Fibonacci MQWs. A
dispersion equation for exciton-polaritons is derived in the two-wave
approximation, the effective allowed and forbidden bands are found. The
reflection spectra from the proposed structures are calculated as a function of
the well number and detuning from the Bragg condition.Comment: 5 pages, 3 figures, submitted to Phys. Rev.
Icosahedral multi-component model sets
A quasiperiodic packing Q of interpenetrating copies of C, most of them only
partially occupied, can be defined in terms of the strip projection method for
any icosahedral cluster C. We show that in the case when the coordinates of the
vectors of C belong to the quadratic field Q[\sqrt{5}] the dimension of the
superspace can be reduced, namely, Q can be re-defined as a multi-component
model set by using a 6-dimensional superspace.Comment: 7 pages, LaTeX2e in IOP styl
Disc loss and renewal in A0535+26
This paper presents observations of the Be/X-ray binary system A0535+26
revealing the first observed loss of its circumstellar disc, demonstrated by
the loss of its JHK infrared excess and optical/IR line emission. However
optical/IR spectroscopy reveals the formation of a new inner disc with
significant density and emission strength at small radii; the disc has proven
to be stable over 5 months in this intermediate state.Comment: 4 pages, 4 figures, accepted by MNRAS, uses mn.st
Speed- and Circuit-Based High-Intensity Interval Training on Recovery Oxygen Consumption
International Journal of Exercise Science 10(7): 942-953, 2017. Due to the current obesity epidemic in the United States, there is growing interest in efficient, effective ways to increase energy expenditure and weight loss. Research has shown that high-intensity exercise elicits a higher Excess Post-Exercise Oxygen Consumption (EPOC) throughout the day compared to steady-state exercise. Currently, there is no single research study that examines the differences in Recovery Oxygen Consumption (ROC) resulting from high-intensity interval training (HIIT) modalities. The purpose of this study is to review the impact of circuit training (CT) and speed interval training (SIT), on ROC in both regular exercising and sedentary populations. A total of 26 participants were recruited from the UW-Eau Claire campus and divided into regularly exercising and sedentary groups, according to self-reported exercise participation status. Oxygen consumption was measured during and after two HIIT sessions and was used to estimate caloric expenditure. There was no significant difference in caloric expenditure during and after exercise among individuals who regularly exercise and individuals who are sedentary. There was also no significant difference in ROC between regular exercisers and sedentary or between SIT and CT. However, there was a significantly higher caloric expenditure in SIT vs. CT regardless of exercise status. It is recommended that individuals engage in SIT vs. CT when the goal is to maximize overall caloric expenditure. With respect to ROC, individuals can choose either modalities of HIIT to achieve similar effects on increased oxygen consumption post-exercise
Physics Behind Precision
This document provides a writeup of contributions to the FCC-ee mini-workshop
on "Physics behind precision" held at CERN, on 2-3 February 2016.Comment: https://indico.cern.ch/event/469561
One Hundred Years of Observations of the Be Star HDE 245770 (the X-ray Binary A0535+26/V725 Tau): The End of an Active Phase
UBV observations of the X-ray binary system A0535+26/V725 Tau at the Crimean
Station of the Sternberg Astronomical Institute in 1980-1998 are presented.
Based on our and published data, we analyze the photometric history of the star
from 1898.Comment: Translated from Pis'ma Astronomicheskii Zhurnal, Vol. 26, No. 1,
2000, pp. 13-2
Symmetry of Magnetically Ordered Quasicrystals
The notion of magnetic symmetry is reexamined in light of the recent
observation of long range magnetic order in icosahedral quasicrystals [Charrier
et al., Phys. Rev. Lett. 78, 4637 (1997)]. The relation between the symmetry of
a magnetically-ordered (periodic or quasiperiodic) crystal, given in terms of a
``spin space group,'' and its neutron diffraction diagram is established. In
doing so, an outline of a symmetry classification scheme for magnetically
ordered quasiperiodic crystals is provided. Predictions are given for the
expected diffraction patterns of magnetically ordered icosahedral crystals,
provided their symmetry is well described by icosahedral spin space groups.Comment: 5 pages. Accepted for publication in Phys. Rev. Letter
Four-dimensional Simulation of the Hot Electroweak Phase Transition with the SU(2) Gauge-Higgs Model
We study the finite-temperature phase transition of the four-dimensional
SU(2) gauge-Higgs model for intermediate values of the Higgs boson mass in the
range 50 \lsim m_H \lsim 100GeV on a lattice with the temporal lattice size
. The order of the transition is systematically examined using finite
size scaling methods. Behavior of the interface tension and the latent heat for
an increasing Higgs boson mass is also investigated.Comment: Talk presented at LATTICE96(electroweak), 3 pages of LaTeX, 4
PostScript figure
Cyclical behaviour and disc truncation in the Be/X-ray binary A0535+26
A0535+26 is shown to display quantised IR excess flux states, which are
interpreted as the first observational verification of the resonant truncation
scheme proposed by Okazaki and Negueruela (2001) for BeXRBs. The simultaneity
of X-ray activity with transitions between these states strongly suggests a
broad mechanism for outbursts, in which material lost from the disc during the
reduction of truncation radius is accreted by the NS. Furthermore changes
between states are shown to be governed by a 1500 day period, probably due to
precession of the Be disc, which profoundly dictates the global behaviour of
the system. Such a framework appears to be applicable to BeXRBs in general.Comment: 10 pages, 11 figs, submitted to MNRA
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