CLIX®Campus and the imc Higher Education E-Learning Network: A Private Public Partnership-Approach to Creating New Educational Benefits.

In: A.J. Kallenberg and M.J.J.M. van de Ven (Eds), 2002, The New Educational Benefits of ICT in Higher Education: Proceedings. Rotterdam: Erasmus Plus BV, OECR ISBN 90-9016127-9The imc Higher Education eLearning Network is a Private Public Partnership in standard e-learning software development. Its goal is to provide universities with a standard platform that fits their specific needs. The paper presents the approach adopted by imc AG and its higher education partners and discusses some of the lessons learned

Lensing and the Centers of Distant Early-Type Galaxies

Gravitational lensing provides a unique probe of the inner 10-1000 pc of distant galaxies (z=0.2-1). Lens theory predicts that every strong lens system should have a faint image near the center of the lens galaxy, which should be visible in radio lenses but have not been observed. We study these ``core'' images using models derived from the stellar distributions in nearby early-type galaxies. We find that realistic galaxies predict a remarkably wide range of core images, with lensing magnifications spanning some six orders of magnitude. More concentrated galaxies produce fainter core images, although not with any simple, quantitative, model independent relation. Some real galaxies have diffuse cores and predict bright core images (magnification mu>~0.1), but more common are galaxies that predict faint core images (mu<~0.001). Thus, stellar mass distributions alone are probably concentrated enough to explain the lack of observed core images, and may require observational sensitivity to improve by an order of magnitude before detections of core images become common. Two-image lenses will tend to have brighter core images than four-image lenses, so they will be the better targets for finding core images and exploiting these tools for studying the central mass distributions of distant galaxies.Comment: 13 pages, emulateapj; submitted to Ap

Lensing magnification of supernovae in the GOODS-fields

Gravitational lensing of high-redshift supernovae is potentially an important source of uncertainty when deriving cosmological parameters from the measured brightness of Type Ia supernovae, especially in deep surveys with scarce statistics. Photometric and spectroscopic measurements of foreground galaxies along the lines-of-sight of 33 supernovae discovered with the Hubble Space Telescope, both core-collapse and Type Ia, are used to model the magnification probability distributions of the sources. Modelling galaxy halos with SIS or NFW-profiles and using M/L scaling laws provided by the Faber-Jackson and Tully-Fisher relations, we find clear evidence for supernovae with lensing (de)magnification. However, the magnification distribution of the Type Ia supernovae used to determine cosmological distances matches very well the expectations for an unbiased sample, i.e.their mean magnification factor is consistent with unity. Our results show that the lensing distortions of the supernova brightness can be well understood for the GOODS sample and that correcting for this effect has a negligible impact on the derived cosmological parameters.Comment: 22 pages, 9 figures, accepted for publication by Ap

Corrections for gravitational lensing of supernovae: better than average?

We investigate the possibility of correcting for the magnification due to gravitational lensing of standard candle sources, such as Type Ia supernovae. Our method uses the observed properties of the foreground galaxies along the lines-of-sight to each source and the accuracy of the lensing correction depends on the quality and depth of these observations as well as the uncertainties in translating the observed luminosities to the matter distribution in the lensing galaxies. The current work is limited to cases where the matter density is dominated by the individual galaxy halos. However, it is straightforward to generalize the method to include also gravitational lensing from cluster scale halos. We show that the dispersion due to lensing for a standard candle source at z=1.5 can be reduced from about 7% to ~< 3%, i.e. the magnification correction is useful in reducing the scatter in the Type Ia Hubble diagram, especially at high redshifts where the required long exposure times makes it hard to reach large statistics and the dispersion due to lensing becomes comparable to the intrinsic Type Ia scatter.Comment: Matches accepted version, includes clarifications and additional issues. 28 pages, 7 figures, accepted for publication in Ap

A general and practical method for calculating cosmological distances

The calculation of distances is of fundamental importance in extragalactic astronomy and cosmology. However, no practical implementation for the general case has previously been available. We derive a second-order differential equation for the angular size distance valid not only in all {\em homogeneous\/} Friedmann-Lemaitre cosmological models, parametrised by \lambda_{0} and \Omega_{0}, but also in {\em inhomogeneous\/} `on-average' Friedmann-Lemaitre models, where the inhomogeneity is given by the (in the general case redshift-dependent) parameter \eta. Since most other cosmological distances can be obtained trivially from the angular size distance, and since the differential equation can be efficiently solved numerically, this offers for the first time a practical method for calculating distances in a large class of cosmological models. We also briefly discuss our numerical implementation, which is publicly available

Grid computing in image analysis

Diagnostic surgical pathology or tissue–based diagnosis still remains the most reliable and specific diagnostic medical procedure. The development of whole slide scanners permits the creation of virtual slides and to work on so-called virtual microscopes. In addition to interactive work on virtual slides approaches have been reported that introduce automated virtual microscopy, which is composed of several tools focusing on quite different tasks. These include evaluation of image quality and image standardization, analysis of potential useful thresholds for object detection and identification (segmentation), dynamic segmentation procedures, adjustable magnification to optimize feature extraction, and texture analysis including image transformation and evaluation of elementary primitives

Neutralino Pair Production and 3-Body Decays at e+e−e^+e^- Linear Colliders as Probes of CP Violation in the Neutralino System

In the CP-invariant supersymmetric theories, the steep S-wave (slow P-wave) rise of the cross section for any non-diagonal neutralino pair production in $e^+ e^-$ annihilation, $e^+e^- \to \tilde{\chi}^0_i \tilde{\chi}^0_j$ ($i \neq j$), near threshold is accompanied by the slow P-wave (steep S-wave) decrease of the fermion invariant mass distribution of the 3-body neutralino decay, $\tilde{\chi}^0_i \to \tilde{\chi}^0_j f\bar{f}$ ($f=l$ or $q$), near the end point. These selection rules, unique to the neutralino system due to its Majorana nature, guarantee that the observation of simultaneous sharp S-wave excitations of the production cross section near threshold and the lepton and quark invariant mass distribution near the end point is a qualitative, unambiguous evidence for CP violation in the neutralino system.Comment: 11 pages, 1 eps figure, a reference adde