441 research outputs found
The 2003-4 multisite photometric campaign for the Beta Cephei and eclipsing star 16 (EN) Lacertae with an Appendix on 2 Andromedae, the variable comparison star
A multisite photometric campaign for the Beta Cephei and eclipsing variable
16 Lacertae is reported. 749 h of high-quality differential photoelectric
Stromgren, Johnson and Geneva time-series photometry were obtained with ten
telescopes during 185 nights. After removing the pulsation contribution, an
attempt was made to solve the resulting eclipse light curve by means of the
computer program EBOP. Although a unique solution was not obtained, the range
of solutions could be constrained by comparing computed positions of the
secondary component in the Hertzsprung-Russell diagram with evolutionary
tracks.
For three high-amplitude pulsation modes, the uvy and the Geneva UBG
amplitude ratios are derived and compared with the theoretical ones for
spherical-harmonic degrees l <= 4. The highest degree, l = 4, is shown to be
incompatible with the observations. One mode is found to be radial, one is l =
1, while in the remaining case l = 2 or 3.
The present multisite observations are combined with the archival photometry
in order to investigate the long-term variation of the amplitudes and phases of
the three high-amplitude pulsation modes. The radial mode shows a
non-sinusoidal variation on a time-scale of 73 yr. The l = 1 mode is a triplet
with unequal frequency spacing, giving rise to two beat-periods, 720.7 d and
29.1 yr. The amplitude and phase of the l = 2 or 3 mode vary on time-scales of
380.5 d and 43 yr.
The light variation of 2 And, one of the comparison stars, is discussed in
the Appendix.Comment: 18 pages, 19 figures, accepted for publication in MNRA
Crack Front Waves and the dynamics of a rapidly moving crack
Crack front waves are localized waves that propagate along the leading edge
of a crack. They are generated by the interaction of a crack with a localized
material inhomogeneity. We show that front waves are nonlinear entities that
transport energy, generate surface structure and lead to localized velocity
fluctuations. Their existence locally imparts inertia, which is not
incorporated in current theories of fracture, to initially "massless" cracks.
This, coupled to crack instabilities, yields both inhomogeneity and scaling
behavior within fracture surface structure.Comment: Embedded Latex file including 4 figure
Asteroseismology of the Beta Cephei star 12 (DD) Lacertae: photometric observations, pulsational frequency analysis and mode identification
We report a multisite photometric campaign for the Beta Cephei star 12
Lacertae. 750 hours of high-quality differential photoelectric Stromgren,
Johnson and Geneva time-series photometry were obtained with 9 telescopes
during 190 nights. Our frequency analysis results in the detection of 23
sinusoidal signals in the light curves. Eleven of those correspond to
independent pulsation modes, and the remainder are combination frequencies. We
find some slow aperiodic variability such as that seemingly present in several
Beta Cephei stars. We perform mode identification from our colour photometry,
derive the spherical degree l for the five strongest modes unambiguously and
provide constraints on l for the weaker modes. We find a mixture of modes of 0
<= l <= 4. In particular, we prove that the previously suspected rotationally
split triplet within the modes of 12 Lac consists of modes of different l;
their equal frequency splitting must thus be accidental.
One of the periodic signals we detected in the light curves is argued to be a
linearly stable mode excited to visible amplitude by nonlinear mode coupling
via a 2:1 resonance. We also find a low-frequency signal in the light
variations whose physical nature is unclear; it could be a parent or daughter
mode resonantly coupled. The remaining combination frequencies are consistent
with simple light-curve distortions.
The range of excited pulsation frequencies of 12 Lac may be sufficiently
large that it cannot be reproduced by standard models. We suspect that the star
has a larger metal abundance in the pulsational driving zone, a hypothesis also
capable of explaining the presence of Beta Cephei stars in the LMC.Comment: 12 pages, 7 figures, MNRAS, in pres
Cymatics for the cloaking of flexural vibrations in a structured plate
Based on rigorous theoretical findings, we present a proof-of-concept design for a structured square cloak enclosing a void in an elastic lattice. We implement high-precision fabrication and experimental testing of an elastic invisibility cloak for flexural waves in a mechanical lattice. This is accompanied by verifications and numerical modelling performed through finite element simulations. The primary advantage of our square lattice cloak, over other designs, is the straightforward implementation and the ease of construction. The elastic lattice cloak, implemented experimentally, shows high efficiency
ChPT tests at the NA48 and NA62 experiments at CERN
The NA48/2 Collaboration at CERN has accumulated unprecedented statistics of
rare kaon decays in the Ke4 modes: Ke4(+-) ()
and Ke4(00) () with nearly one percent
background contamination. The detailed study of form factors and branching
rates, based on these data, has been completed recently. The results brings new
inputs to low energy strong interactions description and tests of Chiral
Perturbation Theory (ChPT) and lattice QCD calculations. In particular, new
data support the ChPT prediction for a cusp in the invariant mass
spectrum at the two charged pions threshold for Ke4(00) decay. New final
results from an analysis of about 400 rare
decay candidates collected by the NA48/2 and NA62 experiments at CERN during
low intensity runs with minimum bias trigger configurations are presented. The
results include a model-independent decay rate measurement and fits to ChPT
description.Comment: XIIth International Conference on Heavy Quarks and Leptons 2014,
Mainz, German
Recent NA48/2 and NA62 results
The NA48/2 Collaboration at CERN has accumulated and analysed unprecedented
statistics of rare kaon decays in the modes: () and ()
with nearly one percent background contamination. It leads to the improved
measurement of branching fractions and detailed form factor studies. New final
results from the analysis of 381 rare decay
candidates collected by the NA48/2 and NA62 experiments at CERN are presented.
The results include a decay rate measurement and fits to Chiral Perturbation
Theory (ChPT) description.Comment: Prepared for the Proceedings of "Moriond QCD and High Energy
Interactions. March 22-29 2014." conferenc
Conference of Soviet and American Jurists on the Law of the Sea and the Protection of the Marine Environment
Included in the papers for the Conference of Soviet and American Jurists on the Law of the Sea and the Protection of the Marine Environment:
Introduction by Milton Katz and Richard R. Baxter, p. 1
Freedom of Scientific Research in the World Ocean by A.F. Vysotsky, p. 7
The International Law of Scientific Research in the Oceans by Richard R. Baxter, p. 27
Responsibility and Liability for Harm to the Marine Environment by Robert E. Stein, p. 41
Liability for Marine Environment Pollution Damage in Contemporary International Sea Law by A. L. Makovsky, p. 59
Protection of the Marine Environment from Pollution by Richard A. Frank, p. 73
The Freedom of Navigation and the Problem of Pollution of the Marine Environment by V. A. Kiselev, p. 93
The Freedom of Navigation Under International Law by William E. Butler, p. 107
International Fisheries Management Without Global Agreement: United States Policies and Their Impact on the Soviet Union by H. Gary Knight, p. 119
Some Biological Background for International Legal Acts on Rational Utilization of the Living Resources of the World Ocean by P. A. Moiseev, p. 143
An International Regime for the Seabed Beyond National Jurisdiction by Thomas M. Franck, p. 151
Settlement of Disputes Under the Law of Ocean Use, with Particular Reference to Environmental Protection by John Lawrence Hargrove, p. 18
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