LISA and LISA PathFinder, the endeavour to detect low frequency GWs

This is a review about LISA and its technology demonstrator, LISA PathFinder. We first describe the conceptual problems which need to be overcome in order to set up a working interferometric detector of low frequency Gravitational Waves (GW), then summarise the solutions to them as currently conceived by the LISA mission team. This will show that some of these solutions require new technological abilities which are still under development, and which need proper test before being fully implemented. LISA PathFinder (LPF) is the the testbed for such technologies. The final part of the paper will address the ideas and concepts behind the PathFinder as well as their impact on LISA.Comment: 25 pages, 21 figures, presented at the Spanish Relativity Meeting, Mallorca September 2006. Will be published in Journal of Physics: Conference Series, IOP. To be published in Journal of Physics: Conference Series, IO

Acceleration disturbances and requirements for ASTROD I

ASTRODynamical Space Test of Relativity using Optical Devices I (ASTROD I) mainly aims at testing relativistic gravity and measuring the solar-system parameters with high precision, by carrying out laser ranging between a spacecraft in a solar orbit and ground stations. In order to achieve these goals, the magnitude of the total acceleration disturbance of the proof mass has to be less than 10−13 m s−2 Hz−1/2 at 0.1 m Hz. In this paper, we give a preliminary overview of the sources and magnitude of acceleration disturbances that could arise in the ASTROD I proof mass. Based on the estimates of the acceleration disturbances and by assuming a simple controlloop model, we infer requirements for ASTROD I. Our estimates show that most of the requirements for ASTROD I can be relaxed in comparison with Laser Interferometer Space Antenna (LISA).Comment: 19 pages, two figures, accepted for publication by Class. Quantum Grav. (at press

diArk 2.0 provides detailed analyses of the ever increasing eukaryotic genome sequencing data

<p>Abstract</p> <p>Background</p> <p>Nowadays, the sequencing of even the largest mammalian genomes has become a question of days with current next-generation sequencing methods. It comes as no surprise that dozens of genome assemblies are released per months now. Since the number of next-generation sequencing machines increases worldwide and new major sequencing plans are announced, a further increase in the speed of releasing genome assemblies is expected. Thus it becomes increasingly important to get an overview as well as detailed information about available sequenced genomes. The different sequencing and assembly methods have specific characteristics that need to be known to evaluate the various genome assemblies before performing subsequent analyses.</p> <p>Results</p> <p>diArk has been developed to provide fast and easy access to all sequenced eukaryotic genomes worldwide. Currently, diArk 2.0 contains information about more than 880 species and more than 2350 genome assembly files. Many meta-data like sequencing and read-assembly methods, sequencing coverage, GC-content, extended lists of alternatively used scientific names and common species names, and various kinds of statistics are provided. To intuitively approach the data the web interface makes extensive usage of modern web techniques. A number of search modules and result views facilitate finding and judging the data of interest. Subscribing to the RSS feed is the easiest way to stay up-to-date with the latest genome data.</p> <p>Conclusions</p> <p>diArk 2.0 is the most up-to-date database of sequenced eukaryotic genomes compared to databases like GOLD, NCBI Genome, NHGRI, and ISC. It is different in that only those projects are stored for which genome assembly data or considerable amounts of cDNA data are available. Projects in planning stage or in the process of being sequenced are not included. The user can easily search through the provided data and directly access the genome assembly files of the sequenced genome of interest. diArk 2.0 is available at <url>http://www.diark.org</url>.</p

The genomic basis of parasitism in the Strongyloides clade of nematodes.

Soil-transmitted nematodes, including the Strongyloides genus, cause one of the most prevalent neglected tropical diseases. Here we compare the genomes of four Strongyloides species, including the human pathogen Strongyloides stercoralis, and their close relatives that are facultatively parasitic (Parastrongyloides trichosuri) and free-living (Rhabditophanes sp. KR3021). A significant paralogous expansion of key gene families--families encoding astacin-like and SCP/TAPS proteins--is associated with the evolution of parasitism in this clade. Exploiting the unique Strongyloides life cycle, we compare the transcriptomes of the parasitic and free-living stages and find that these same gene families are upregulated in the parasitic stages, underscoring their role in nematode parasitism

Nutzung der Satelliten-Navigationssysteme GPS und GLONASS fuer die zivile Luftfahrt.

Die beiden militaerischen Navigationssysteme GPS und GLONASS sollen in Zukunft auch in der zivilen Luftfahrt genutzt werden. Beide Systeme koennen aber nicht alle Anforderungen erfuellen, die an eine genaue und sichere Navigation zu stellen sind. Deshalb werden derzeit Ergaenzungen zu den Satellitensystemen untersucht, die diese Maengel beheben sollen. Die Anforderungen, die die zivile Luftfahrt stellen muss, werden zusammengestellt. Moeglichkeiten der Ergaenzung zu GPS/GLONASS werden genannt

Anforderungen der zivilen Luftfahrt an ein globales Satellitennavigationssystem.

Es wird die Leistungsfaehigkeit der Satellitensysteme GPS und GLONASS den Anforderungen von ICAO an ein zukuenftiges Navigationssystem gegenuebergestellt. Moeglichkeiten der Verbesserung und Ergaenzung, um zu einem globalen zivilen Navigationssystem zu gelangen, werden genannt