4,167 research outputs found

    Agglutinated foraminifera from neritic to bathyal facies in the Palaeogene of Spitsbergen and the Barents Sea

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    Late Palaeocene to Early Eocene foraminiferal assemblages have been analysed from an exploratory well (7119/7-1) drilled in the TromsĂž Basin (southwestern Barents Sea) and from two onshore sections, Basilikaelva and Kovalskifjella, exposed in the Central Tertiary Basin of Spitsbergen. The assemblages reveal marked differences in taxonomic composition and diversity, reflecting inner neritic to middle bathyal conditions. Within this depth range, four foraminiferal biofacies (FB) are distinguished: FB 1 occurs in the Kolthoffberget Member (of the Firkanten Formation, Late Palaeocene) sampled in the Basilikaelva section. The member consists of interbedded shales, siltstones and sandstones deposited in a transitional delta front - prodelta environment, according to current sedimentological interpretation. The foraminiferal assemblages are entirely agglutinated, show extremely low species diversities and strong dominance of Reticulophragmium arcticum followed by Labrospira aff. turbida. FB 2 is recognised in the Basilika Formation (Late Palaeocene) exposed in the Kovalskifjella section. The formation consists of silty claystones deposited in a prodelta shelf setting. The foraminiferal assemblages show an increased species diversity, and consist mainly of agglutinated taxa with a strongly subordinate calcareous component. The two most abundant species are R. arcticum and L. aff. turbida. Species of Verneuilinoides and Trochammina occur in significant numbers while tubular taxa are rare. FB 3 is found in the Lower Eocene clay interval composing the upper part of the Torsk Formation in well 7119/7-1. It contains entirely agglutinated assemblages with comparatively high diversities. The dominant species are Recurvoides aff. turbinatus and Budashevaella multicamerata, while Reticulophragmium amplectens is typical and common in these strata. Tubular forms referred to Rhizammina occur locally in significant quantities. The diversity and composition of the assemblages suggest an outer neritic to upper bathyal environment. FB 4 is developed in Palaeocene claystones comprising the lower part of the Torsk Formation in well 7119/7-1. In this interval the species diversity, as well as the frequency of tubular forms (referred to Rhizammina, Bathysiphon and Hyperammina) attains maximum values. Other common to dominant taxa include Spiroplectammina spectabilis, Haplophragmoides walteri, Ammosphaeroidina pseudopauciloculata, and Recurvoides sp. These wholly agglutinated assemblages are interpreted as reflecting upper to middle bathyal conditions

    The KM-Algorithm Identifies Regulated Genes in Time Series Expression Data

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    We present a statistical method to rank observed genes in gene expression time series experiments according to their degree of regulation in a biological process. The ranking may be used to focus on specific genes or to select meaningful subsets of genes from which gene regulatory networks can be built. Our approach is based on a state space model that incorporates hidden regulators of gene expression. Kalman (K) smoothing and maximum (M) likelihood estimation techniques are used to derive optimal estimates of the model parameters upon which a proposed regulation criterion is based. The statistical power of the proposed algorithm is investigated, and a real data set is analyzed for the purpose of identifying regulated genes in time dependent gene expression data. This statistical approach supports the concept that meaningful biological conclusions can be drawn from gene expression time series experiments by focusing on strong regulation rather than large expression values

    Tunable-filter imaging of quasar fields at z ~ 1. II. The star-forming galaxy environments of radio-loud quasars

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    We have scanned the fields of six radio-loud quasars using the Taurus Tunable Filter to detect redshifted [OII] 3727 line-emitting galaxies at redshifts 0.8 < z < 1.3. Forty-seven new emission-line galaxy (ELG) candidates are found. This number corresponds to an average space density about 100 times that found locally and, at L([OII]) < 10^{42} erg s^{-1} cm^{-2}, is 2 - 5 times greater than the field ELG density at similar redshifts, implying that radio-loud quasars inhabit sites of above-average star formation activity. The implied star-formation rates are consistent with surveys of field galaxies at z ~ 1. However, the variation in candidate density between fields is large and indicative of a range of environments, from the field to rich clusters. The ELG candidates also cluster -- both spatially and in terms of velocity -- about the radio sources. In fields known to contain rich galaxy clusters, the ELGs lie at the edges and outside the concentrated cores of red, evolved galaxies, consistent with the morphology-density relation seen in low-redshift clusters. This work, combined with other studies, suggests that the ELG environments of powerful AGN look very much the same from moderate to high redshifts, i.e. 0.8 < z < 4.Comment: 18 pages, 18 figures, uses emulateapj.cls. Accepted for publication in A

    Slowing Down and Scattering of Ions in Solids

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    The interaction of particle beams with solids yields three parts, i.e. reflected particles, penetrating particles and trapped particles. At very low energies particle reflection is dominant, at very high energies penetration is the most important effect. Trapped particles are the result of energy loss processes, which on the other hand cause radiation damage in the solid. In the energy range discussed here, i.e. above energies where quantum effects, diffraction etc. are important and below energies where nuclear reactions, relativistic effects etc. may occur, the particle trajectories are classical. The energy loss process can be treated separately as nuclear and electronic stopping power. The collisions of the projectiles with target atoms are hence binary collisions involving a properly chosen screened Coulomb-potential. In single crystals the structural properties enable channeling, which is a very useful tool in sol id state analysis. The electronic stopping includes contributions from single collision processes and collective excitations. Both effects can be described by a dielectric response function. The range of applications covers analytical methods, means to modify solid state properties and also the production of thin films

    SPUTTER DEPTH PROFILING OF OPTICAL WAVEGUIDES USING SECONDARY ION MASS SPECTROMETRY

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    The technique of sputter depth profiling by means of secondary ion mass spectrometry of samples with high resistivity is reviewed. As examples we discuss optical waveguides made in lithium niobate by titanium indiffusion and implantation and also yttrium iron garnet waveguides grown by liquid phase epitaxy on gadolinium gallium garnet. Depth profiling of these waveguide structures has been performed and the necessary precautions to prevent charging by the primary ion beam are discussed. In some cases, coating with a metallic layer is adequate, but a more universal method is charge neutralization by an additional electron beam

    AnsÀtze zur Ordnungsreduktion von nichtlinearen Oszillatormodellen zur Anwendung im Schaltungsentwurf

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    Im Rahmen dieser Arbeit wird ein Konzept zur Ordnungsreduktion von höherdimensionalen nichtlinearen Oszillatormodellen vorgestellt. Hierbei werden zwei wesentliche Ziele verfolgt. Zum einen wird eine höherdimensionale Modellierung der Oszillatorschaltung verwendet. Hierdurch lassen sich die EinflĂŒsse parasitĂ€rer Effekte sowie struktureller Erweiterungen auf das dynamische Verhalten des Systems berĂŒcksichtigen. Zum anderen wird durch eine anschließende Ordnungsreduktion ĂŒber die Methode der Zentrumsmannigfaltigkeit eine zweidimensionale Systembeschreibung erzeugt, deren wesentliche Dynamik derjenigen des höherdimensionalen Systems entspricht. Durch diese, in der Ordnung reduzierte, nichtlineare und parameterabhĂ€ngige Systembeschreibung wird die Anwendbarkeit nichtlinearer Analysemethoden ermöglicht bzw. vereinfacht. Mit der Anwendung der Andronov-Hopf-Bifurkationsanalyse auf das reduzierte System lĂ€sst sich eine StabilitĂ€tsuntersuchung durchfĂŒhren sowie die Amplitude und Frequenz aller ZustandsgrĂ¶ĂŸen approximieren. Das vorgestellte Konzept wird anhand des Beispielsystems eines LC-Tank-VCOs durchgefĂŒhrt. <br><br> In this paper, an order reduction technique for higher-dimensional nonlinear oscillator models, based on a center manifold approach, is presented. By modeling the oscillator circuit in the higher-dimensional state space, influences of parasitic elements and of structural extensions of the oscillator architecture on the dynamical system behavior can be examined. Using the proposed order reduction technique, a generalized second order model will be derived, which includes selected design parameters of the higher order model. By using an Andronov-Hopf bifurcation analysis, the reduced system can be studied with respect to stability as well as the amplitude and frequency of the individual state variables. The concept is applied to the design of LC-tank VCOs

    A bioinformatics approach to the development of immunoassays for specified risk material in canned meat products

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    A bioinformatics approach to developing antibodies to specific proteins has been evaluated for the production of antibodies to heat-processed specified risk tissues from ruminants (brain and eye tissue). The approach involved the identification of proteins specific to ruminant tissues by interrogation of the annotation fields within the Swissprot database. These protein sequences were then interrogated for peptide sequences that were unique to the protein. Peptides were selected that met these criteria as close as possible and that were also theoretically resistant to either pepsin or trypsin. The selected peptides were synthesised and used as immunogens to raise monoclonal antibodies. Antibodies specific for the synthetic peptides were raised to half of the selected peptides. These antibodies have each been incorporated into a competitive enzyme-linked immunosorbent assay (ELISA) and shown to be able to detect the heat-processed parent protein after digestion with either pepsin or trypsin. One antibody, specific for alpha crystallin peptide (from bovine eye tissue), was able to detect the peptide in canned meat products spiked with 10% eye tissue. These results, although preliminary in nature, show that bioinformatics in conjunction with enzyme digestion can be used to develop ELISA for proteins in high-temperature processed foods and demonstrate that the approach is worth further stud

    Growth Responses of Zoysia spp. under Tree Shade in the Midwestern United States

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    ‘Meyer’ zoysiagrass (Zoysia japonica Steudel) is commonly planted on home lawns and golf courses in the transition zone; however, poor shade tolerance limits its widespread use. This study was conducted to determine changes and differences in growth among selected Zoysia cultivars and progeny under a natural shade environment over a 3-year period in the transition zone. The study was initiated in June 2010 at the Rocky Ford Turfgrass Research Center in Manhattan, KS. Soil type was a Chase silt loam (fine, montmorillonitic, mesic, Aquic, Argiudoll). Zoysia genotypes were sodded in 0.37-m2 plots and arranged in a randomized complete block with five replications under silver maple (Acer saccharinum L.) shade that resulted in a 91% reduction in photosynthetically active radiation (PAR). Genotypes included ‘Zorro’ [Z. matrella (L.) Merrill], ‘Emerald’ [Z. japonica × Z. pacifica (Goudswaard) Hotta & Kuroki], ‘Meyer’, Chinese Common (Z. japonica), and experimental progeny Exp1 (Z. matrella × Z. japonica), and Exp2 and Exp3 [(Z. japonica × Z. pacifica) × Z. japonica]. ‘Zorro’ and ‘Emerald’ experienced winter injury, which negatively affected their performance. Tiller numbers decreased 47% in ‘Meyer’ from June 2010 to June 2012, but declines in [(Z. japonica × Z. pacifica) × Z. japonica] progeny were only 1% for Exp2 and 27% for Exp3, and both Exp2 and Exp3 maintained high percent green cover throughout the study. In general, by the third year of evaluation, progeny of [(Z. japonica × Z. pacifica) × Z. japonica] had higher quality ratings and higher tiller numbers than ‘Meyer’ and may provide more shade-tolerant cultivar choices for transition zone turf managers
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