Thin-disk laser pump schemes for large number of passes and moderate pump source quality

Novel thin-disk laser pump layouts are proposed yielding an increased number of passes for a given pump module size and pump source quality. These novel layouts result from a general scheme which bases on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard commercially available pump optics simply by intro ducing an additional mirror-pair. More pump passes yield better efficiency, opening the way for usage of active materials with low absorption. In a standard multi-pass pump design, scaling of the number of beam passes brings ab out an increase of the overall size of the optical arrangement or an increase of the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applicationsComment: 16 pages, 9 figure

MetaBar - a tool for consistent contextual data acquisition and standards compliant submission

Background: Environmental sequence datasets are increasing at an exponential rate; however, the vast majority of them lack appropriate descriptors like sampling location, time and depth/altitude: generally referred to as metadata or contextual data. The consistent capture and structured submission of these data is crucial for integrated data analysis and ecosystems modeling. The application MetaBar has been developed, to support consistent contextual data acquisition. Results: MetaBar is a spreadsheet and web-based software tool designed to assist users in the consistent acquisition, electronic storage, and submission of contextual data associated to their samples. A preconfigured Microsoft Excel spreadsheet is used to initiate structured contextual data storage in the field or laboratory. Each sample is given a unique identifier and at any stage the sheets can be uploaded to the MetaBar database server. To label samples, identifiers can be printed as barcodes. An intuitive web interface provides quick access to the contextual data in the MetaBar database as well as user and project management capabilities. Export functions facilitate contextual and sequence data submission to the International Nucleotide Sequence Database Collaboration (INSDC), comprising of the DNA DataBase of Japan (DDBJ), the European Molecular Biology Laboratory database (EMBL) and GenBank. MetaBar requests and stores contextual data in compliance to the Genomic Standards Consortium specifications. The MetaBar open source code base for local installation is available under the GNU General Public License version 3 (GNU GPL3). Conclusion: The MetaBar software supports the typical workflow from data acquisition and field-sampling to contextual data enriched sequence submission to an INSDC database. The integration with the megx.net marine Ecological Genomics database and portal facilitates georeferenced data integration and metadata-based comparisons of sampling sites as well as interactive data visualization. The ample export functionalities and the INSDC submission support enable exchange of data across disciplines and safeguarding contextual data

Observation of Long-Lived Muonic Hydrogen in the 2S State

The kinetic energy distribution of ground state muonic hydrogen atoms mu-p(1S) is determined from time-of-flight spectra measured at 4, 16, and 64 hPa H2 room-temperature gas. A 0.9 keV-component is discovered and attributed to radiationless deexcitation of long-lived mu-p(2S) atoms in collisions with H2 molecules. The analysis reveals a relative population of about 1%, and a pressure-dependent lifetime (e.g. (30.4 +21.4 -9.7) ns at 64 hPa) of the long-lived mu-p(2S) population, equivalent to a 2S-quench rate in mu-p(2S) + H2 collisions of (4.4 +2.1 -1.8) 10^11 s^-1 at liquid hydrogen density.Comment: 4 pages, 2 figures, accepted for publication in Physical Review Letter

Angular distributions of scattered excited muonic hydrogen atoms

Differential cross sections of the Coulomb deexcitation in the collisions of excited muonic hydrogen with the hydrogen atom have been studied for the first time. In the framework of the fully quantum-mechanical close-coupling approach both the differential cross sections for the $nl \to n'l'$ transitions and $l$-averaged differential cross sections have been calculated for exotic atom in the initial states with the principle quantum number $n=2 - 6$ at relative motion energies $E_{\rm {cm}}=0.01 - 15$ eV and at scattering angles $\theta_{\rm {cm}}=0 - 180^{\circ}$. The vacuum polarization shifts of the $ns$-states are taken into account. The calculated in the same approach differential cross sections of the elastic and Stark scattering are also presented. The main features of the calculated differential cross sections are discussed and a strong anisotropy of cross sections for the Coulomb deexcitation is predicted.Comment: 5 pages, 9 figure

Assessment of lipid uptake and fatty acid metabolism of European eel larvae (Anguilla anguilla) determined by 14C in vivo incubation

Knowledge on dietary nutrient requirements of first-feeding European eel larvae (Anguilla anguilla) is very limited. This study provides first ever information on in vivo lipid uptake and fatty acid (FA) metabolism of European pre-leptocephalus eel larvae and advances directions for dietary lipid and FA inclusions. The in vivo capability of eel larvae to incorporate and metabolize unsaturated fatty acids was tested on larvae at different ontogenetic stages (4, 8 and 12 days post hatch, DPH). Larvae were incubated in 10 mL flat-bottom tissue culture plates, with [1-14C]-labelled FA (18:2n-6, ALA; 18:3n-3, LA; 20:4n-6, ARA and 20:5n-3, EPA) directly added to seawater. The capability of the larvae for de-acylation and re-acylation of [1-14C]arachidonic acid (ARA), initially bound to phosphatidylcholine (PC) and phosphatidylethanolamine (PE), was also investigated. In all cases, control incubations without any radiolabelled substrate were performed for further lipid analysis. The results revealed that direct incubation with 14C-labelled FA is a feasible method to investigate in vivo FA and phospholipids metabolism of pre-leptocephalus stages of the European eel. No enzymatic elongation/desaturation activity towards [1-14C]C18 or [1-14C]C20 FA was detected. Consequently, ARA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) must be considered essential FA and thus provided firstly through female broodstock and later through diet at least during the first-feeding stage. Pre-leptocephalus larvae display a high capacity to remodel dietary phospholipids with a preferential esterification of all FA substrates into PC. The unexpectedly high esterification rate of [1-14C] ARA into PC and PE is supported by the individual FA profiles of the larval phospholipids. The high levels of ARA present in the European eel larvae denotes its physiological relevance for this species. It is therefore essential to consider this FA as particularly important when designing suitable broodstock – or first-feeding diets for this species

Data shopping in an open marketplace: Introducing the Ontogrator web application for marking up data using ontologies and browsing using facets

In the future, we hope to see an open and thriving data market in which users can find and select data from a wide range of data providers. In such an open access market, data are products that must be packaged accordingly. Increasingly, eCommerce sellers present heterogeneous product lines to buyers using faceted browsing. Using this approach we have developed the Ontogrator platform, which allows for rapid retrieval of data in a way that would be familiar to any online shopper. Using Knowledge Organization Systems (KOS), especially ontologies, Ontogrator uses text mining to mark up data and faceted browsing to help users navigate, query and retrieve data. Ontogrator offers the potential to impact scientific research in two major ways: 1) by significantly improving the retrieval of relevant information; and 2) by significantly reducing the time required to compose standard database queries and assemble information for further research. Here we present a pilot implementation developed in collaboration with the Genomic Standards Consortium (GSC) that includes content from the StrainInfo, GOLD, CAMERA, Silva and Pubmed databases. This implementation demonstrates the power of ontogration and highlights that the usefulness of this approach is fully dependent on both the quality of data and the KOS (ontologies) used. Ideally, the use and further expansion of this collaborative system will help to surface issues associated with the underlying quality of annotation and could lead to a systematic means for accessing integrated data resources

Non-regularly shaped plasmon resonant nanoparticle as localized light source for near-field microscopy

We study numerically two-dimensional nanoparticles with a non-regular shape and demonstrate that these particles can support many more plasmon resonances than a particle with a regular shape (e.g. an ellipse). The electric field distributions associated with these different resonances are investigated in detail in the context of near-field microscopy. Depending on the particle shape, extremely strong and localized near-fields, with intensity larger than 10(5) that of the illumination wave, can be generated. We also discuss the spectral dependence of these near-fields and show that different spatial distributions are observed, depending which plasmon resonance is excited in the particle

Spectral response of plasmon resonant nanoparticles with a non-regular shape

We study the plasmon resonances of 10 - 100 (nm) two-dimensional metal particles with a non-regular shape. Movies illustrate the spectral response of such particles in the optical range. Contrary to particles with a simple shape (cylinder, ellipse) non-regular particles exhibit many distinct resonances ver a large spectral range. At resonance frequencies, extremely large enhancements of the electromagnetic fields occur near the surface of the particle, with amplitudes several hundredfold that of the incident field. Implications of these str ng and localized fields for nano-optics and surface enhanced Raman scattering (SERS) are also discussed. (C) 2000 Optical Society of America

Field polarization and polarization charge distributions in plasmon resonant nanoparticles

We study the plasmon resonances for small two-dimensional silver particles (nanowires) with elliptical or triangular shapes in the 20 nm size range. While the elliptical particle has only two resonances, a well known fact, we demonstrate that the triangular particle displays a much more complex behaviour with several resonances over a broad wavelength range. Using animations of the field amplitude and field polarization, we investigate the properties of these different resonances. The field distribution associated with each plasmon resonance can be related to the polarization charges on the surface of the particles. Implications for the design of plasmon resonant structures with specific properties, for example, for nano-optics or surface enhanced Raman scattering are discussed

Dramatic localized electromagnetic enhancement in plasmon resonant nanowires

We investigate numerically the plasmon resonances of 10-50 nm nanowires with a non-elliptical section. Such wires have a much more complex behavior than elliptical wires and their resonances span a larger frequency range. The field distribution at the surface of these wires exhibits a dramatic enhancement, up to several hundred times the incident field amplitude. These strongly localized fields can provide an important mechanism for surface enhanced Raman scattering (SERS). (C) 2001 Elsevier Science B.V. All rights reserved