6,246 research outputs found
Remarks on the Theory of Cosmological Perturbation
It is shown that the power spectrum defined in the Synchronous Gauge can not
be directly used to calculate the predictions of cosmological models on the
large-scale structure of universe, which should be calculated directly by a
suitable gauge-invariant power spectrum or the power spectrum defined in the
Newtonian Gauge.Comment: 13 pages, 1 figure, minor changes, to be published in Chinese Physics
Letter
Simple solutions of relativistic hydrodynamics for systems with ellipsoidal symmetry
Simple, self-similar, analytic solutions of (1+3)-dimensional relativistic
hydrodynamics are presented for ellipsoidally symmetric finite fireballs
corresponding to non-central collisions of heavy ions at relativistic
bombarding energies. The hydrodynamical solutions are obtained for a new,
general family of equations of state with the possibility of describing phase
transitions.Comment: 13 pages, no figures, uses elsart.cl
Color Gradients in Early-Type Galaxies in Clusters at the Redshift from 0.37 to 0.56
Color gradients in elliptical galaxies in distant clusters ()
are examined by using the archival deep imaging data of Wide Field Planetary
Camera 2 (WFPC2) on-board the Hubble Space Telescope (HST). Obtained color
gradients are compared with the two model gradients to examine the origin of
the color gradients. In one model, a color gradient is assumed to be caused by
a metallicity gradient of stellar populations, while in the other one, it is
caused by an age gradient. Both of these model color gradients reproduce the
average color gradient seen in nearby ellipticals, but predict significantly
different gradients at a redshift larger than 0.3. Comparison between the
observed gradients and the model gradients reveals that the metallicity
gradient is much more favorable as the primary origin of color gradients in
elliptical galaxies in clusters. The same conclusion has been obtained for
field ellipticals by using those at the redshift from 0.1 to 1.0 in the Hubble
Deep Field-North by Tamura et al. (2000). Thus, it is also suggested that the
primary origin of the color gradients in elliptical galaxies does not depend on
galaxy environment.Comment: 23 pages LaTeX, 5 PostScript figures, accepted for publication in The
Astronomical Journa
Homogeneity of Stellar Populations in Early-Type Galaxies with Different X-ray Properties
We have found the stellar populations of early-type galaxies are homogeneous
with no significant difference in color or Mg2 index, despite the dichotomy
between X-ray extended early-type galaxies and X-ray compact ones. Since the
X-ray properties reflect the potential gravitational structure and hence the
process of galaxy formation, the homogeneity of the stellar populations implies
that the formation of stars in early-type galaxies predat es the epoch when the
dichotomy of the potential structure was established.Comment: 6 pages, 5 figures, accepted for publication in Ap
Transient cosmic ray increase associated with a geomagnetic storm
On the basis of worldwide network data of cosmic ray nucleonic components, the transient cosmic ray increase due to the depression of cosmic ray cutoff rigidity during a severe geomagnetic storm was investigated in terms of the longitudinal dependence. Multiple correlation analysis among isotropic and diurnal terms of cosmic ray intensity variations and Dst term of the geomagnetic field is applied to each of various station's data. It is shown that the amplitude of the transient cosmic ray increase associated with Dst depends on the local time of the station, and that its maximum phase is found in the evening sector. This fact is consistent with the theoretical estimation based on the azimuthally asymmetric ring current model for the magnetic DS field
Classification of the line-soliton solutions of KPII
In the previous papers (notably, Y. Kodama, J. Phys. A 37, 11169-11190
(2004), and G. Biondini and S. Chakravarty, J. Math. Phys. 47 033514 (2006)),
we found a large variety of line-soliton solutions of the
Kadomtsev-Petviashvili II (KPII) equation. The line-soliton solutions are
solitary waves which decay exponentially in -plane except along certain
rays. In this paper, we show that those solutions are classified by asymptotic
information of the solution as . Our study then unravels some
interesting relations between the line-soliton classification scheme and
classical results in the theory of permutations.Comment: 30 page
Paleomagnetism of granitic intrusives from the basement under eastern Kansas
The Precambrian basement under east-central Kansas was drilled at two circular aeromagnetic positives, one at Osawatomie and one at Big Springs. The core retrieved from these sites is a coarse- to medium-grained granite which has been dated by U-Pb to be 1,350 m.y. old. The paleomagnetism of these azimuthally unoriented cores was studied to see if a technique which uses low-coercivity, low-temperature magnetization components to orient the cores would allow an independent confirmation of the core's mid-Proterozoic age. Orthogonal-projection plots of the alternating field (at) and thermal-demagnetization data show that the magnetization of these cores is relatively simple. Both cores have a low-temperature/low-coercivity magnetization with steep positive inclinations. The Osawatomie core's characteristic magnetization has a shallow, negative inclination, and the Big Springs core has a positive, moderate-inclination characteristic magnetization. If the declination of the low-temperature/low-coercivity component is aligned parallel to the present field declination, the characteristic directions may be azimuthally oriented. This allows the calculation of paleomagnetic poles for the Big Springs core (lat. = 4.5°S, long. = 29.9°E) and the Osawatomie core (lat. = 20.2°N, long. = 39.3 °E), which are consistent with Irving's (1979) apparent polar-wander path for Laurentia at about 1,300-1,400 m.y
Paleomagnetism of granitic intrusives from the basement under eastern Kansas
The Precambrian basement under east-central Kansas was drilled at two circular aeromagnetic positives, one at Osawatomie and one at Big Springs. The core retrieved from these sites is a coarse- to medium-grained granite which has been dated by U-Pb to be 1,350 m.y. old. The paleomagnetism of these azimuthally unoriented cores was studied to see if a technique which uses low-coercivity, low-temperature magnetization components to orient the cores would allow an independent confirmation of the core's mid-Proterozoic age. Orthogonal-projection plots of the alternating field (at) and thermal-demagnetization data show that the magnetization of these cores is relatively simple. Both cores have a low-temperature/low-coercivity magnetization with steep positive inclinations. The Osawatomie core's characteristic magnetization has a shallow, negative inclination, and the Big Springs core has a positive, moderate-inclination characteristic magnetization. If the declination of the low-temperature/low-coercivity component is aligned parallel to the present field declination, the characteristic directions may be azimuthally oriented. This allows the calculation of paleomagnetic poles for the Big Springs core (lat. = 4.5°S, long. = 29.9°E) and the Osawatomie core (lat. = 20.2°N, long. = 39.3 °E), which are consistent with Irving's (1979) apparent polar-wander path for Laurentia at about 1,300-1,400 m.y
Method for monitoring urea and ammonia in wine and must by flow injection-pervaporation
An easy to automate flow-injection-pervaporation method for monitoring urea and ammonia in must and wine was developed. The method is based on separation of the ammonia from the sample matrix by pervaporation followed by its reaction with salicylate, hypochlorite and nitroprusside to form a diazonium salt with maximum absorption at 647 nm. Conversion of urea into ammonia catalysed by urease was mandatory before pervaporation. After optimisation by either the univariate or multivariate approaches as required, the linear range was established (between 0 and 25 mg l-1) for both analytes. Then, the assessment of the proposed method versus a reference one for urea and ammonia was studied in terms of repeatability (0.52 mg l-1 and 0.43 mg l-1, respectively), reproducibility (1.34 mg l-1 and 1.21 mg l-1, respectively), detection and quantification limits (LOD=0.9 and 0.6 mg l-1, LQ=1.02 and 0.67 mg l-1, respectively) and traceability. The sample throughput was 16 samples h-1. The method can be applied to the monitoring of the target analytes in must and young wine in order to control their contents, preventing formation of ethyl carbamate
Perturbative analysis of wave interactions in nonlinear systems
This work proposes a new way for handling obstacles to asymptotic
integrability in perturbed nonlinear PDEs within the method of Normal Forms -
NF - for the case of multi-wave solutions. Instead of including the whole
obstacle in the NF, only its resonant part is included, and the remainder is
assigned to the homological equation. This leaves the NF intergable and its
solutons retain the character of the solutions of the unperturbed equation. We
exploit the freedom in the expansion to construct canonical obstacles which are
confined to te interaction region of the waves. Fo soliton solutions, e.g., in
the KdV equation, the interaction region is a finite domain around the origin;
the canonical obstacles then do not generate secular terms in the homological
equation. When the interaction region is infifnite, or semi-infinite, e.g., in
wave-front solutions of the Burgers equation, the obstacles may contain
resonant terms. The obstacles generate waves of a new type, which cannot be
written as functionals of the solutions of the NF. When an obstacle contributes
a resonant term to the NF, this leads to a non-standard update of th wave
velocity.Comment: 13 pages, including 6 figure
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