1,441 research outputs found
The Ellipticity of the Disks of Spiral Galaxies
The disks of spiral galaxies are generally elliptical rather than circular.
The distribution of ellipticities can be fit with a log-normal distribution.
For a sample of 12,764 galaxies from the Sloan Digital Sky Survey Data Release
1 (SDSS DR1), the distribution of apparent axis ratios in the i band is best
fit by a log-normal distribution of intrinsic ellipticities with ln epsilon =
-1.85 +/- 0.89. For a sample of nearly face-on spiral galaxies, analyzed by
Andersen and Bershady using both photometric and spectroscopic data, the best
fitting distribution of ellipticities has ln epsilon = -2.29 +/- 1.04. Given
the small size of the Andersen-Bershady sample, the two distribution are not
necessarily inconsistent. If the ellipticity of the potential were equal to
that of the light distribution of the SDSS DR1 galaxies, it would produce 1.0
magnitudes of scatter in the Tully-Fisher relation, greater than is observed.
The Andersen-Bershady results, however, are consistent with a scatter as small
as 0.25 magnitudes in the Tully-Fisher relation.Comment: 19 pages, 5 figures; ApJ, accepte
Anomalous Spin Dynamics observed by High Frequency ESR in Honeycomb Lattice Antiferromagnet InCu2/3V1/3O3
High-frequency ESR results on the S=1/2 Heisenberg hexagonal antiferromagnet
InCu2/3V1/3O3 are reported. This compound appears to be a rare model substance
for the honeycomb lattice antiferromagnet with very weak interlayer couplings.
The high-temperature magnetic susceptibility can be interpreted by the S=1/2
honeycomb lattice antiferromagnet, and it shows a magnetic-order-like anomaly
at TN=38 K. Although, the resonance field of our high-frequency ESR shows the
typical behavior of the antiferromagnetic resonance, the linewidth of our
high-frequency ESR continues to increase below TN, while it tends to decrease
as the temperature in a conventional three-dimensional antiferromagnet
decreases. In general, a honeycomb lattice antiferromagnet is expected to show
a simple antiferromagnetic order similar to that of a square lattice
antiferromagnet theoretically because both antiferromagnets are bipartite
lattices. However, we suggest that the observed anomalous spin dynamics below
TN is the peculiar feature of the honeycomb lattice antiferromagnet that is not
observed in the square lattice antiferromagnet.Comment: 5 pages, 5 figure
1.5 Decades Later: Bearing fruits from the ACR/EULAR exchange Program
Imaging Science & TechnologyApplied Science
Predicting risk for radiographic damage in rheumatoid arthritis:comparative analysis of the multi-biomarker disease activity score and conventional measures of disease activity in multiple studies
Pathophysiology and treatment of rheumatic disease
Sexual harassment and abuse in sport: The research context
This special issue of the Journal of Sexual Aggression draws on the contributions to a Symposium on âSexual Harassment in Sport â Challenges for Sport Psychology in the New Millenniumâ, held at the Xth Congress of the International Society for Sport Psychology, Skiathos, Greece from May 28th to June 2nd 2001. The symposium, which was organised by the authors of this editorial, was intended to move forward the international research agenda on sexual harassment and abuse in sport and to examine professional practice issues for sport psychologists. It was clear from the attendance of over 60 delegates at that symposium that international interest in this subject is growing. Further evidence of this came from the attendance of 26 members states â from Azerbaijan to Sweden - at a Council of Europe seminar on The Protection of Children, Young People and Women in Sport, held in Helsinki in September 2001
Phase diagram of a Heisenberg spin-Peierls model with quantum phonons
Using a new version of the density-matrix renormalization group we determine
the phase diagram of a model of an antiferromagnetic Heisenberg spin chain
where the spins interact with quantum phonons. A quantum phase transition from
a gapless spin-fluid state to a gapped dimerized phase occurs at a non-zero
value of the spin-phonon coupling. The transition is in the same universality
class as that of a frustrated spin chain, which the model maps to in the
anti-adiabatic limit. We argue that realistic modeling of known spin-Peierls
materials should include the effects of quantum phonons.Comment: RevTeX, 5 pages, 3 eps figures included using epsf. Improved theories
in adiabatic and non-adiabatic regimes give better agreement with DMRG. This
version accepted in Physical Review Letter
Application of Hybrid Frequency Domain Substructuring for Modelling an Automotive Engine Suspension
Study trip as means of expanded learning
This article explores the study trip as an interconnected activity of work and play, constituting an extended means of teaching design studio in spatial design related disciplines. This study analyses the case of a cohort of about 200 students involved in a joint project in three cities, Athens, Tokyo and London, where groups were challenged with a common project brief. The students conducted empirical studies of the cities through play and enjoyment. The case study provides evidence of the benefits and issues emerging in this particular teaching and learning method of project-based and field work research in spatial design
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