4,180 research outputs found
Agglutinated foraminifera from neritic to bathyal facies in the Palaeogene of Spitsbergen and the Barents Sea
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
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
Slowing Down and Scattering of Ions in Solids
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
Tunable-filter imaging of quasar fields at z ~ 1. II. The star-forming galaxy environments of radio-loud quasars
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
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Long-term variations of the mesospheric wind field at mid-latitudes
Continuous MF radar observations at the station Juliusruh (54.6° N; 13.4° E) have been analysed for the time interval between 1990 and 2005, to obtain information about solar activity-induced variations, as well as long-term trends in the mesospheric wind field. Using monthly median values of the zonal and the meridional prevailing wind components, as well as of the amplitude of the semidiurnal tide, regression analyses have been carried out with a dependence on solar activity and time. The solar activity causes a significant amplification of the zonal winds during summer (increasing easterly winds) and winter (increasing westerly winds). The meridional wind component is positively correlated with the solar activity during summer but during winter the correlation is very small and non significant. Also, the solar influence upon the amplitude of the semidiurnal tidal component is relatively small (in dependence on height partly positive and partly negative) and mostly non-significant.
The derived trends in the zonal wind component during summer are below an altitude of about 83 km negative and above this height positive. During the winter months the trends are nearly opposite compared with the trends in summer (transition height near 86 km). The trends in the meridional wind components are below about 85 km positive in summer (significant) and near zero (nonsignificant) in winter; above this height during both seasons negative trends have been detected. The trends in the semidiurnal tidal amplitude are at all heights positive, but only partly significant.
The detected trends and solar cycle dependencies are compared with other experimental results and model calculations. There is no full agreement between the different results, probably caused by different measuring techniques and evaluation methods used. Also, different heights and observation periods investigated may contribute to the detected differences
SPUTTER DEPTH PROFILING OF OPTICAL WAVEGUIDES USING SECONDARY ION MASS SPECTROMETRY
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
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 anschlieĂende 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
parameterabhÀngige Systembeschreibung wird die Anwendbarkeit nichtlinearer
Analysemethoden ermöglicht bzw. vereinfacht. Mit der Anwendung der
Andronov-Hopf-Bifurkationsanalyse auf das reduzierte System lÀsst sich eine
StabilitĂ€tsuntersuchung durchfĂŒhren sowie die Amplitude und Frequenz aller
ZustandsgröĂen approximieren. Das vorgestellte Konzept wird anhand des
Beispielsystems eines LC-Tank-VCOs durchgefĂŒhrt.
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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
Growth Responses of Zoysia spp. under Tree Shade in the Midwestern United States
âMeyerâ 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 âZorroâ [Z. matrella (L.) Merrill], âEmeraldâ [Z. japonica Ă Z. pacifica (Goudswaard) Hotta & Kuroki], âMeyerâ, Chinese Common (Z. japonica), and experimental progeny Exp1 (Z. matrella Ă Z. japonica), and Exp2 and Exp3 [(Z. japonica Ă Z. pacifica) Ă Z. japonica]. âZorroâ and âEmeraldâ experienced winter injury, which negatively affected their performance. Tiller numbers decreased 47% in âMeyerâ from June 2010 to June 2012, but declines in [(Z. japonica Ă Z. pacifica) Ă 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 Ă Z. pacifica) Ă Z. japonica] had higher quality ratings and higher tiller numbers than âMeyerâ and may provide more shade-tolerant cultivar choices for transition zone turf managers
Estimating Transpiration from Turfgrass Using Stomatal Conductance Values Derived from Infrared Thermometry
Infrared thermometry provides accurate measurements of plant canopy temperature, which, along with basic weather variables, allows estimation of canopy stomatal conductance to water vapor flux (gc) and transpiration. Using this method we compared modeled estimates of transpiration (CONDT) with evapotranspiration (ET) measurements from nearby microlysimeters (LYSET) in tall fescue (Schedonorus arundinaceus Schreb.) turfgrass. Results indicated transpiration may be reliably estimated via calculation of gc in turfgrass
A bioinformatics approach to the development of immunoassays for specified risk material in canned meat products
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
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