2,4-Dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid monohydrate

The title compound, C5H4N2O 4·H2O, a uracil derivative, contains several important functional groups, which give rise to its use in biomedical applications. The crystal structure consists of molecules held together by extensive intermolecular hydrogen bonding between neighbouring pyrimidine rings and between the acid groups and water molecules, resulting in a layered sheet structure. The asymmetric unit contains two molecules of the carboxylic acid and two water molecules. © 2004 International Union of Crystallography Printed in Great Britain - all rights reserved.published_or_final_versio

Resolved stellar population of distant galaxies in the ELT era

The expected imaging capabilities of future Extremely Large Telescopes (ELTs) will offer the unique possibility to investigate the stellar population of distant galaxies from the photometry of the stars in very crowded fields. Using simulated images and photometric analysis we explore here two representative science cases aimed at recovering the characteristics of the stellar populations in the inner regions of distant galaxies. Specifically: case A) at the center of the disk of a giant spiral in the Centaurus Group, (mu B~21, distance of 4.6 Mpc); and, case B) at half of the effective radius of a giant elliptical in the Virgo Cluster (mu~19.5, distance of 18 Mpc). We generate synthetic frames by distributing model stellar populations and adopting a representative instrumental set up, i.e. a 42 m Telescope operating close to the diffraction limit. The effect of crowding is discussed in detail showing how stars are measured preferentially brighter than they are as the confusion limit is approached. We find that (i) accurate photometry (sigma~0.1, completeness >90%) can be obtained for case B) down to I~28.5, J~27.5 allowing us to recover the stellar metallicity distribution in the inner regions of ellipticals in Virgo to within ~0.1 dex; (ii) the same photometric accuracy holds for the science case A) down to J~28.0, K~27.0, enabling to reconstruct of the star formation history up to the Hubble time via simple star counts in diagnostic boxes. For this latter case we discuss the possibility of deriving more detailed information on the star formation history from the analysis of their Horizontal Branch stars. We show that the combined features of high sensitivity and angular resolution of ELTs may open a new era for our knowledge of the stellar content of galaxies of different morphological type up to the distance of the Virgo cluster.Comment: 21 pages, 17 figures, PASP accepted in pubblicatio

Spatially dependent Rabi oscillations: an approach to sub-diffraction-limited CARS microscopy

We present a theoretical investigation of coherent anti-Stokes Raman scattering (CARS) that is modulated by periodically depleting the ground state population through Rabi oscillations driven by an additional control laser. We find that such a process generates optical sidebands in the CARS spectrum and that the frequency of the sidebands depends on the intensity of the control laser light field. We show that analyzing the sideband frequency upon scanning the beams across the sample allows one to spatially resolve emitter positions where a spatial resolution of 65 nm, which is well below the diffraction-limit, can be obtained

The commutator Hopf Galois extensions

Let H be a finite dimentional Hopf algebra over a field k and H∗ the dual Hopf algebra of H. Then a commutator right H∗ -Galois extension B of BH is characterized in terms of the smash product B#H and some relationships between such a B and the Hopf Galois Azumaya or Hopf Galois Hirata extensions are also given

Anforderungen an Musik-Discovery-Systeme: Handreichungen zur Optimierung von Benutzeroberflächen

This is an English language version of the German language article cited below. “Discovery” has become a library buzzword but it refers to a traditional concept: enabling users to find library information and materials. Discovery was first facilitated by print indexes and card catalogs, then later by online library catalogs and search engines. Today, the discovery environment is changing rapidly both within libraries and externally. Within the library realm, FRBR, RDA, discovery tools, and faceted browsing are key factors related to these changes in the way our users navigate searches and encounter library data. The newest discovery interfaces aim to remove barriers between different types of data and incorporate aspects of non-library online searching environments familiar to users. When discovery interfaces work well, everyone benefits: the library’s collections are more fully exposed, and users do not have to adhere to nor struggle with the shortcomings of complicated search vocabularies and strategies. Discovery is optimized