Modified algebraic Bethe ansatz for XXZ chain on the segment - III - Proof

In this paper, we prove the off-shell equation satisfied by the transfer matrix associated with the XXZ spin-$\frac12$ chain on the segment with two generic integrable boundaries acting on the Bethe vector. The essential step is to prove that the expression of the action of a modified creation operator on the Bethe vector has an off-shell structure which results in an inhomogeneous term in the eigenvalues and Bethe equations of the corresponding transfer matrix.Comment: V2 published version, 16 page

Air Quality Model Evaluation Data for Organics. 2. C_1−C_(14) Carbonyls in Los Angeles Air

As part of a larger experiment that provides a comprehensive set of observations to be used for testing air quality models for organic air pollutant transport and reaction, ambient air samples have been collected using DNPH-coated C_(18) cartridges at four urban locations and one background location in the Los Angeles area and have been analyzed for carbonyls as their DNPH derivatives. Twenty-three carbonyls have been identified and their concentrations measured:  14 aliphatic aldehydes (from formaldehyde to tetradecanal), two aromatics (benzaldehyde and m-tolualdehyde), three ketones (acetone, 2-butanone, and cyclohexanone), one unsaturated carbonyl (crotonaldehyde), and three dicarbonyls (glyoxal, methylglyoxal, and biacetyl). Another 19 carbonyls have been tentatively identified including 11 low molecular weight (MW) and intermediate MW carbonyls (of which four may be due to reactions of ambient NO, NO_2, and ozone with DNPH on the sampling cartridge), four C_4−C_6 dicarbonyls present at trace levels, and four high MW aliphatic carbonyls (C_(15)−C_(18)). Total carbonyl concentrations (4-h samples) averaged 22 ppb at the urban locations and 3.5 ppb at the background location and were highest (29 ppb) at the Azusa, CA, monitoring site that is downwind of downtown Los Angeles. Formaldehyde (urban average 5.3 ppb), acetaldehyde, and acetone accounted for 24%, 18%, and 7%, respectively, of the total carbonyls on a ppbv basis. The nine high MW carbonyls (C_8−C_(14)) accounted for 11−14% of the total carbonyls. The acetaldehyde/formaldehyde concentration ratio averaged 0.75 at the urban locations. Ranking of the measured carbonyls with respect to removal of the hydroxyl radical showed acetaldehyde to be the most important followed by formaldehyde and nonanal. Diurnal and spatial variations in ambient carbonyls levels are briefly examined and appear to be consistent with both direct emissions and in-situ formation during eastward transport over the urban area

Theoretical power spectra of mixed modes in low mass red giant stars

CoRoT and Kepler observations of red giant stars revealed very rich spectra of non-radial solar-like oscillations. Of particular interest was the detection of mixed modes that exhibit significant amplitude, both in the core and at the surface of the stars. It opens the possibility of probing the internal structure from their inner-most layers up to their surface along their evolution on the red giant branch as well as on the red-clump. Our objective is primarily to provide physical insight into the physical mechanism responsible for mixed-modes amplitudes and lifetimes. Subsequently, we aim at understanding the evolution and structure of red giants spectra along with their evolution. The study of energetic aspects of these oscillations is also of great importance to predict the mode parameters in the power spectrum. Non-adiabatic computations, including a time-dependent treatment of convection, are performed and provide the lifetimes of radial and non-radial mixed modes. We then combine these mode lifetimes and inertias with a stochastic excitation model that gives us their heights in the power spectra. For stars representative of CoRoT and Kepler observations, we show under which circumstances mixed modes have heights comparable to radial ones. We stress the importance of the radiative damping in the determination of the height of mixed modes. Finally, we derive an estimate for the height ratio between a g-type and a p-type mode. This can thus be used as a first estimate of the detectability of mixed-modes

Protection of Works of Art From Atmospheric Ozone

Assesses the colorfastness of organic colorants and watercolor pigments tested in atmospheric ozone. A summary of a full report of the Environmental Quality Laboratory, California Institute of Technology, Pasadena

Angular momentum redistribution by mixed modes in evolved low-mass stars. I. Theoretical formalism

Seismic observations by the space-borne mission \emph{Kepler} have shown that the core of red giant stars slows down while evolving, requiring an efficient physical mechanism to extract angular momentum from the inner layers. Current stellar evolution codes fail to reproduce the observed rotation rates by several orders of magnitude, and predict a drastic spin-up of red giant cores instead. New efficient mechanisms of angular momentum transport are thus required. In this framework, our aim is to investigate the possibility that mixed modes extract angular momentum from the inner radiative regions of evolved low-mass stars. To this end, we consider the Transformed Eulerian Mean (TEM) formalism, introduced by Andrews \& McIntyre (1978), that allows us to consider the combined effect of both the wave momentum flux in the mean angular momentum equation and the wave heat flux in the mean entropy equation as well as their interplay with the meridional circulation. In radiative layers of evolved low-mass stars, the quasi-adiabatic approximation, the limit of slow rotation, and the asymptotic regime can be applied for mixed modes and enable us to establish a prescription for the wave fluxes in the mean equations. The formalism is finally applied to a $1.3 M_\odot$ benchmark model, representative of observed CoRoT and \emph{Kepler} oscillating evolved stars. We show that the influence of the wave heat flux on the mean angular momentum is not negligible and that the overall effect of mixed modes is to extract angular momentum from the innermost region of the star. A quantitative and accurate estimate requires realistic values of mode amplitudes. This is provided in a companion paper.Comment: Accepted in A&A, 11 pages, and 6 figure

Discrete Cylindrical Vector Beam Generation from an Array of Optical Fibers

A novel method is presented for the beam shaping of far field intensity distributions of coherently combined fiber arrays. The fibers are arranged uniformly on the perimeter of a circle, and the linearly polarized beams of equal shape are superimposed such that the far field pattern represents an effective radially polarized vector beam, or discrete cylindrical vector (DCV) beam. The DCV beam is produced by three or more beams that each individually have a varying polarization vector. The beams are appropriately distributed in the near field such that the far field intensity distribution has a central null. This result is in contrast to the situation of parallel linearly polarized beams, where the intensity peaks on axis

Angular momentum redistribution by mixed modes in evolved low-mass stars. II. Spin-down of the core of red giants induced by mixed modes

The detection of mixed modes in subgiants and red giants by the CoRoT and \emph{Kepler} space-borne missions allows us to investigate the internal structure of evolved low-mass stars. In particular, the measurement of the mean core rotation rate as a function of the evolution places stringent constraints on the physical mechanisms responsible for the angular momentum redistribution in stars. It showed that the current stellar evolution codes including the modelling of rotation fail to reproduce the observations. An additional physical process that efficiently extracts angular momentum from the core is thus necessary. Our aim is to assess the ability of mixed modes to do this. To this end, we developed a formalism that provides a modelling of the wave fluxes in both the mean angular momentum and the mean energy equations in a companion paper. In this article, mode amplitudes are modelled based on recent asteroseismic observations, and a quantitative estimate of the angular momentum transfer is obtained. This is performed for a benchmark model of 1.3 $M_{\odot}$ at three evolutionary stages, representative of the evolved pulsating stars observed by CoRoT and Kepler. We show that mixed modes extract angular momentum from the innermost regions of subgiants and red giants. However, this transport of angular momentum from the core is unlikely to counterbalance the effect of the core contraction in subgiants and early red giants. In contrast, for more evolved red giants, mixed modes are found efficient enough to balance and exceed the effect of the core contraction, in particular in the hydrogen-burning shell. Our results thus indicate that mixed modes are a promising candidate to explain the observed spin-down of the core of evolved red giants, but that an other mechanism is to be invoked for subgiants and early red giants.Comment: Accepted in A&A, 7 pages, 8 figure

Air Quality Model Evaluation Data for Organics. 2. C_1−C_(14) Carbonyls in Los Angeles Air

As part of a larger experiment that provides a comprehensive set of observations to be used for testing air quality models for organic air pollutant transport and reaction, ambient air samples have been collected using DNPH-coated C_(18) cartridges at four urban locations and one background location in the Los Angeles area and have been analyzed for carbonyls as their DNPH derivatives. Twenty-three carbonyls have been identified and their concentrations measured:  14 aliphatic aldehydes (from formaldehyde to tetradecanal), two aromatics (benzaldehyde and m-tolualdehyde), three ketones (acetone, 2-butanone, and cyclohexanone), one unsaturated carbonyl (crotonaldehyde), and three dicarbonyls (glyoxal, methylglyoxal, and biacetyl). Another 19 carbonyls have been tentatively identified including 11 low molecular weight (MW) and intermediate MW carbonyls (of which four may be due to reactions of ambient NO, NO_2, and ozone with DNPH on the sampling cartridge), four C_4−C_6 dicarbonyls present at trace levels, and four high MW aliphatic carbonyls (C_(15)−C_(18)). Total carbonyl concentrations (4-h samples) averaged 22 ppb at the urban locations and 3.5 ppb at the background location and were highest (29 ppb) at the Azusa, CA, monitoring site that is downwind of downtown Los Angeles. Formaldehyde (urban average 5.3 ppb), acetaldehyde, and acetone accounted for 24%, 18%, and 7%, respectively, of the total carbonyls on a ppbv basis. The nine high MW carbonyls (C_8−C_(14)) accounted for 11−14% of the total carbonyls. The acetaldehyde/formaldehyde concentration ratio averaged 0.75 at the urban locations. Ranking of the measured carbonyls with respect to removal of the hydroxyl radical showed acetaldehyde to be the most important followed by formaldehyde and nonanal. Diurnal and spatial variations in ambient carbonyls levels are briefly examined and appear to be consistent with both direct emissions and in-situ formation during eastward transport over the urban area

Non-diagonal open spin-1/2 XXZ quantum chains by separation of variables: Complete spectrum and matrix elements of some quasi-local operators

The integrable quantum models, associated to the transfer matrices of the 6-vertex reflection algebra for spin 1/2 representations, are studied in this paper. In the framework of Sklyanin's quantum separation of variables (SOV), we provide the complete characterization of the eigenvalues and eigenstates of the transfer matrix and the proof of the simplicity of the transfer matrix spectrum. Moreover, we use these integrable quantum models as further key examples for which to develop a method in the SOV framework to compute matrix elements of local operators. This method has been introduced first in [1] and then used also in [2], it is based on the resolution of the quantum inverse problem (i.e. the reconstruction of all local operators in terms of the quantum separate variables) plus the computation of the action of separate covectors on separate vectors. In particular, for these integrable quantum models, which in the homogeneous limit reproduce the open spin-1/2 XXZ quantum chains with non-diagonal boundary conditions, we have obtained the SOV-reconstructions for a class of quasi-local operators and determinant formulae for the covector-vector actions. As consequence of these findings we provide one determinant formulae for the matrix elements of this class of reconstructed quasi-local operators on transfer matrix eigenstates.Comment: 40 pages. Minor modifications in the text and some notations and some more reference adde