Photometric parameters of edge-on galaxies from 2MASS observations

To analyze the vertical structure of edge-on galaxies, we have used images of a large uniform sample of flat galaxies that have been taken during the 2MASS all-sky survey. The photometric parameters, such as the radial scale length, the vertical scale height, and the deprojected central surface brightness of galactic disks have been obtained. We find a strong correlation between the central surface brightness and the ratio of the vertical scale height to the vertical scale length: the thinner the galaxy, the lower the central surface brightness of its disk. The vertical scale height does not increase systematically with the distance from the galaxy center in the frames of this sample.Comment: 7 pages, 5 postscript figures. To be published in Astronomy & Astrophysics, v. 389, p.795, 200

Preservation of panorama mesdag, the Haque

This paper deals with the preservation of the Panorama Mesdag, a cylindrical painting, more than 14 meters high and 120 meters in circumference. The vista of the sea, the dunes and Scheveningen village was painted by one of the most famous painters of the Hague School, Hendrik Willem Mesdag. It is the oldest 19th century panorama in the world in its original site and a unique cultural heritage. About three years ago the building, which is a uniquely complex structure, was damaged by a nearby excavation. In the years to follow a series of measures have been taken of which the compensation grouting of the foundation is the most extensive from a geotechnical point of view.\ud This paper outlines the history of the damage, the construction of the building and most importantly the extents of the compensation grouting and the result of the grouting and the extensive monitoring. The effectiveness of the grouting is determined and conclusions have been drawn for the still to be performed excavations and construction activities

Use of the multinomial jack-knife and bootstrap in generalized non-linear canonical correlation analysis

In this paper we discuss the estimation of mean and standard errors of the eigenvalues and category quantifications in generalized non-linear canonical correlation analysis (OVERALS). Starting points are the delta method equations, but the jack-knife and bootstrap are used to provide finite difference approximations to the derivatives

Electronic Study Books and learning style

Attention has been drawn to the concepts of Electronic Books and Electronic Study Books. Several publications have discussed some main ideas (paradigms) for both concepts. For the Electronic Study Book as a learning environment, it is essential to consider individual modes of learning, usually termed 'learning styles'. It is argued that Electronic Study Books should be adaptable in accordance with personal learning styles. Some options will be presented to link 'styles' and 'books'. One such option is a Style Initiating Module which we are currently investigating

On the thermodynamical limit of self-gravitating systems

It is shown that the diluted thermodynamical limit of a self-gravitating system proposed by de Vega and Sanchez suffers from the same problems as the usual thermodynamical limit and leads to divergent thermodynamical functions. This question is also discussed from the point of view of mean field theory.Comment: 11 pages. A typo corrected. Cosmetic changes in some equations. Version that appear in the journa

Theoretical study on the protonation of AZA-aromatics

The protonation of azanaphthalenes and azabenzenes has been studied theoretically using CNDO/2 wavefunctions and perturbation theory in order to examine the correlation between pKa values and quantum-mechanical quantities

Kinematics and dynamics of the "superthin" edge-on disk galaxy IC 5249

We present spectroscopic observations of the stellar motions in the disk of the superthin edge-on spiral galaxy IC 5249 and re-analyse synthesis observations of the HI. We find that the HI rotation curve rises initially to about 90-100 km/s, but contrary to the conclusion of Abe et al. (1999) flattens well before the edge of the optical disk. Over most part of the optical disk we have been able to establish that the (tangential) stellar velocity dispersion is 25-30 km/s. From earlier surface photometry we adopt a value for the radial scalelength of the disk of 7 +/- 1 kpc, a vertical scaleheight of 0.65 +/- 0.05 kpc and a disk truncation radius of 17 +/- 1 kpc. The very thin appearance of IC 5249 on the sky is the result of a combination of a low (face-on) surface brightness, a long scalelength and a a sharp truncation at only about 2.5 scalelengths. From various arguments we derive the stellar velocity dispersions at a position one radial scalelength as sigma_R about 35 km/s, sigma_{theta} about 30 km/s and sigma_z about 20 km/s. This is comparable to the values for the disk of our Galaxy in the solar neighborhood.Comment: 11 pages and 8 figures. Accepted for Astronomy and Astrophysics (September 2001