522 research outputs found
Canonical gauge-invariant variables for scalar perturbations in synchronous coordinates
Under an appropriate change of the perturbation variable Lifshitz-Khalatnikov
propagation equations for the scalar perturbation reduce to d'Alembert
equation. The change of variables is based on the Darboux transform.Comment: LaTeX, 9 page
Infringed Versus Infringing : Different Interpretations of the Word Work and the Effect on the Deterrence Goal of Copyright Law
One of the key elements that courts use to determine an appropriate statutory damage award in a copyright infringement case is the number of infringements of a copyright. How does a court determine the number of infringements when one infringing article has been printed six times in over one hundred copies of a magazine? Before the Copyright Act of 1976 went into effect, many courts adhered to the multiplicity doctrine and would have awarded statutory damages in the above scenarios for each of the six times that the infringing article was printed or the infringing song was played. Post-1976, however, most courts have interpreted the 1976 Act\u27s language as abolishing the practice of awarding statutory damages for each infringing work, instead awarding statutory damages for each infringed work. In 2004, the First Circuit reaffirmed this interpretation in Venegas-Hernandez v. Sonolux Records. Although the law may appear to be well-settled, two questions remain. First, does this interpretation of the 1976 Act actually deter prospective infringers-one of the goals of copyright law? And, second, does this interpretation promote good public policy? Evidence seems to suggest that the answers to both of these questions are in the negative
Comparison of the Symbiotic Fauna of the Family Plethodontidae in the Ouachita Mountains of Western Arkansas
During the spring of 1985, 101 salamanders representing six host species (29 Plethodon ouachitae, 25 P. caddoensis, 6 P. fourchensis, 23 P. serratus, 13 Desmognathus brimleyorum, and 5 P. glutinosus glutinosus) were collected from six localities in three counties in Arkansas (Polk, Scott, and Montgomery) and examined for symbionts. With the exception of Hannemania dunni, all symbionts recovered from the first five species listed constitute new host records, and the endoparasitic fauna in all species establish new locality records. Examinations revealed one or more species of parasites in 82% of the hosts. Eight species of symbionts (3 nematode, 1 trematode, 1 cestode, 1 protozoan, 1 arthropod, and 1 cystacanth acanthocephalon) were recovered. Conclusions are based on the three host species examined in the largest numbers. Thelandros magnavulvularis and H. dunni were the most commonly occurring parasites, found in five and four host species respectively. Cepedietta michiganensis was restricted to P. ouachitae and Brachycoelium storeriae to P. caddoensis. Hannemania dunni was absent in P. serratus
Free expansion of a Bose-Einstein condensate at the presence of a thermal cloud
We investigate numerically the free-fall expansion of a Rb atoms
condensate at nonzero temperatures. The classical field approximation is used
to separate the condensate and the thermal cloud during the expansion. We
calculate the radial and axial widths of the expanding condensate and find
clear evidence that the thermal component changes the dynamics of the
condensate. Our results are confronted against the experimental data
The Management of the Weather Risk on the Electric Energy Market
The aim of this study is to present a new approach for analyzing the effect of temperatures, wind speed and heating degree days index on the variability of the daily demand for electric energy in Silesian region. Specific nature of the time series used in this paper concerning the electric energy consumption and the weather variables, such as temperature or heating degree day index, requires application of a special class of models —ARFIMAX—GARCH (Generalized Autoregressive Conditional Heteroscedastic model).Рассмотрен новый подход к анализу влияния температуры, скорости ветра и индекса степени дневного нагрева на изменчивость суточного потребления электроэнергии в районе Силезии. Особенности используемых временных рядов связаны с потреблением электроэнергии и погодными переменными, такими как температура или индекс степени дневного нагрева, обусловливают применение специального класса моделей — ARFIMAX—GARCH (обобщенная авторегрессионная условная гетероскедастическая модель).Розглянуто новий підхід до аналізу впливу температури, швидкості вітру та індексу ступеню денного нагріву на змінність добової потреби в електроенергії в районі Сілезії. Властивості використаних часових рядів, пов’язані з споживанням електроенергії та погодними змінними, такими як температура чи індекс ступеню денного нагріву, обумовлюють застосування спеціального класу моделей — ARFIMAX—GARCH (узагальнена авторегресійна умовна гетероскедастична модель)
Probe spectroscopy in an operating magneto-optical trap: the role of Raman transitions between discrete and continuum atomic states
We report on cw measurements of probe beam absorption and four-wave-mixing
spectra in a Rb magneto-optical trap taken while the trap is in
operation. The trapping beams are used as pump light. We concentrate on the
central feature of the spectra at small pump-probe detuning and attribute its
narrow resonant structures to the superposition of Raman transitions between
light-shifted sublevels of the ground atomic state and to atomic recoil
processes. These two contributions have different dependencies on trap
parameters and we show that the former is inhomogeneously broadened. The strong
dependence of the spectra on the probe-beam polarization indicates the
existence of large optical anisotropy of the cold-atom sample, which is
attributed to the recoil effects. We point out that the recoil-induced
resonances can be isolated from other contributions, making pump-probe
spectroscopy a highly sensitive diagnostic tool for atoms in a working MOT.Comment: 9 pages, 8 figure
Ultimate stability of active optical frequency standards
Active optical frequency standards provide interesting alternatives to their
passive counterparts. Particularly, such a clock alone continuously generates
highly-stable narrow-line laser radiation. Thus a local oscillator is not
required to keep the optical phase during a dead time between interrogations as
in passive clocks, but only to boost the active clock's low output power to
practically usable levels with the current state of technology. Here we
investigate the spectral properties and the stability of active clocks,
including homogeneous and inhomogeneous broadening effects. We find that for
short averaging times the stability is limited by photon shot noise from the
limited emitted laser power and at long averaging times by phase diffusion of
the laser output. Operational parameters for best long-term stability were
identified. Using realistic numbers for an active clock with Sr we find
that an optimized stability of is achievable.Comment: 15 page
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