3,417 research outputs found
Spin induced multipole moments for the gravitational wave amplitude from binary inspirals to 2.5 Post-Newtonian order
Using the NRGR effective field theory formalism we calculate the remaining
source multipole moments necessary to obtain the spin contributions to the
gravitational wave amplitude to 2.5 Post-Newtonian (PN) order. We also
reproduce the tail contribution to the waveform linear in spin at 2.5PN arising
from the nonlinear interaction between the current quadrupole and the mass
monopole.Comment: 17 pages, 4 figures. v2 Minor changes, to appear in JCA
Spin induced multipole moments for the gravitational wave flux from binary inspirals to third Post-Newtonian order
Using effective field theory techniques we calculate the source multipole
moments needed to obtain the spin contributions to the power radiated in
gravitational waves from inspiralling compact binaries to third Post-Newtonian
order (3PN). The multipoles depend linearly and quadratically on the spins and
include both spin(1)spin(2) and spin(1)spin(1) components. The results in this
paper provide the last missing ingredient required to determine the phase
evolution to 3PN including all spin effects which we will report in a separate
paper.Comment: 35 pages, 7 figures. Published versio
Next to leading order spin-orbit effects in the motion of inspiralling compact binaries
Using effective field theory (EFT) techniques we calculate the
next-to-leading order (NLO) spin-orbit contributions to the gravitational
potential of inspiralling compact binaries. We use the covariant spin
supplementarity condition (SSC), and explicitly prove the equivalence with
previous results by Faye et al. in arXiv:gr-qc/0605139. We also show that the
direct application of the Newton-Wigner SSC at the level of the action leads to
the correct dynamics using a canonical (Dirac) algebra. This paper then
completes the calculation of the necessary spin dynamics within the EFT
formalism that will be used in a separate paper to compute the spin
contributions to the energy flux and phase evolution to NLO.Comment: 25 pages, 4 figures, revtex4. v2: minor changes, refs. added. To
appear in Class. Quant. Gra
Optical bistability in subwavelength apertures containing nonlinear media
We develop a self-consistent method to study the optical response of metallic
gratings with nonlinear media embedded within their subwavelength slits. An
optical Kerr nonlinearity is considered. Due to the large E-fields associated
with the excitation of the transmission resonances appearing in this type of
structures, moderate incoming fluxes result in drastic changes in the
transmission spectra. Importantly, optical bistability is obtained for certain
ranges of both flux and wavelength.Comment: 4 pages, 4 figure
Higher-order spin effects in the dynamics of compact binaries II. Radiation field
Motivated by the search for gravitational waves emitted by binary black
holes, we investigate the gravitational radiation field of point particles with
spins within the framework of the multipolar-post-Newtonian wave generation
formalism. We compute: (i) the spin-orbit (SO) coupling effects in the binary's
mass and current quadrupole moments one post-Newtonian (1PN) order beyond the
dominant effect, (ii) the SO contributions in the gravitational-wave energy
flux and (iii) the secular evolution of the binary's orbital phase up to 2.5PN
order. Crucial ingredients for obtaining the 2.5PN contribution in the orbital
phase are the binary's energy and the spin precession equations, derived in
paper I of this series. These results provide more accurate gravitational-wave
templates to be used in the data analysis of rapidly rotating Kerr-type
black-hole binaries with the ground-based detectors LIGO, Virgo, GEO 600 and
TAMA300, and the space-based detector LISA.Comment: includes the correction of an erratum to be published in Phys. Rev.
Seleção de fungos produtores de β-D-frutosiltransferase por fermentação em estado sólido
A enzima β-D-frutosiltransferase é responsável pela síntese de FOS (frutooligossacarídeos) a partir de sacarose por reação de transfrutosilação é produzida por diferentes micro-organismos, principalmente por fungos filamentosos. O objetivo deste trabalho foi selecionar a melhor linhagem fúngica produtora da -D-frutosiltransferase por fermentação em estado sólido, bem como o método de extração. A fermentação em estado sólido utilizando o substrato farelo de trigo umedecido com solução de sacarose atingindo 70% de umidade na concentração de esporos de 107 no tempo de 96 horas de crescimento. Todas as linhagens manipuladas apresentaram atividade hidrolítica, no entanto apenas uma linhagem não demonstrou atividade transfrutosilação. O isolado SIS 14 que pertence ao gênero Aspergillus sp. destacou-se pelos maiores valores em atividade no método de extração utilizando água destilada, apresentando 300,90 U/mL na atividade de transfrutosilação e na atividade hidrolítica de 155,74 U/mL. Contudo, pode-se perceber que dos solventes estudados a água destilada foi melhor obtendo o valor em atividade de transfrutosilação, como também a linhagem SIS 14 é promissora para a produção da β-D-frutosiltransferase
Optimized minigaps for negative differential resistance creation in strongly delta-doped (1D) superlattices
The "atomic saw method" uses the passage of dislocations in two-dimensional
(2D) quantum-well superlattices to create periodic slipping layers and
one-dimensional (1D) quantum wire superlattices. The effects of this space
structuring of the samples on the allowed energies are analysed in the case of
GaAs d-doped superlattices. If they are sufficiently large, the various
minigaps appearing in the 1D band structure could be responsible for the
presence of negative differential resistance (NDR) with high critical current
in these systems. The purpose is to determine the evolution of the minigaps in
terms of the sample parameters and to obtain the means to determine both the 2D
and 1D structural characteristics where NDR could appear.Comment: see erratum 10.1006/spmi.1998.070
On the transmission of light through a single rectangular hole
In this Letter we show that a single rectangular hole exhibits transmission
resonances that appear near the cutoff wavelength of the hole waveguide. For
light polarized with the electric field pointing along the short axis, it is
shown that the normalized-to-area transmittance at resonance is proportional to
the ratio between the long and short sides, and to the dielectric constant
inside the hole. Importantly, this resonant transmission process is accompanied
by a huge enhancement of the electric field at both entrance and exit
interfaces of the hole. These findings open the possibility of using
rectangular holes for spectroscopic purposes or for exploring non-linear
effects.Comment: Submitted to PRL on Feb. 9th, 200
Study and characterization by magnetophonon resonance of the energy structuring in GaAs/AlAs quantum-wire superlattices
We present the characterization of the band structure of GaAs/AlAs
quantum-wire 1D superlattices performed by magnetophonon resonance with pulsed
magnetic fields up to 35 T. The samples, generated by the "atomic saw method"
from original quantum-well 2D superlattices, underwent substantial
modifications of their energy bands built up on the X-states of the bulk. We
have calculated the band structure by a finite element method and we have
studied the various miniband structures built up of the masses m_t and m_l of
GaAs and AlAs at the point X. From an experimental point of view, the main
result is that in the 2D case we observe only resonances when the magnetic
field B is applied along the growth axis whereas in the 1D case we obtain
resonances in all magnetic field configurations. The analysis of the maxima (or
minima for B // E) in the resistivity rho_xy as a function of B allows us to
account, qualitatively and semi-quantitatively, for the band structure
theoretically expected
A Bose-Einstein Condensate in a Uniform Light-induced Vector Potential
We use a two-photon dressing field to create an effective vector gauge
potential for Bose-condensed Rb atoms in the F=1 hyperfine ground state. The
dressed states in this Raman field are spin and momentum superpositions, and we
adiabatically load the atoms into the lowest energy dressed state. The
effective Hamiltonian of these neutral atoms is like that of charged particles
in a uniform magnetic vector potential, whose magnitude is set by the strength
and detuning of Raman coupling. The spin and momentum decomposition of the
dressed states reveals the strength of the effective vector potential, and our
measurements agree quantitatively with a simple single-particle model. While
the uniform effective vector potential described here corresponds to zero
magnetic field, our technique can be extended to non-uniform vector potentials,
giving non-zero effective magnetic fields.Comment: 5 pages, submitted to Physical Review Letter
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