12,031 research outputs found
Nd & Hf concentrations and isotopic compositions in the Baltic Sea
Within a process study in the framework of the international GEOTRACES program and led by the Institute of Oceanology of the Polish Academy of Sciences (IOPAN) a two-week cruise on the R/V Oceania sailed in November 2011 to investigate the distribution of trace elements and their isotopes in the Baltic Sea. The scientific goals were particularly focused on compiling trace element budgets for the Baltic Sea including in- and outflow, as well as to investigate elemental behavior and isotopic fractionation associated with the redox gradients of the Baltic Sea water column and the permanently anoxic conditions within its deep basins (i.e. Gotland Deep, Landsort Deep).
The Baltic Sea is a shallow, brackish inland sea with an average salinity of ~7 psu in the mixed layer. It is fed by the Bothnian Sea in the north, by the Finland Sea in the east, as well as by numerous rivers from Scandinavia and the Baltic states, and it is drained through the Danish Strait into the North Sea. In the opposite direction, a denser bottom water mass enters the Baltic Sea through deeper channels from the Danish Strait successively filling the deep basins northward. Below 130 m water depth, the water column is permanently anoxic.
Here we present the first combined data set of Nd and Hf concentrations and isotopic compositions for the Baltic Sea. A total of 21 water samples (60L volume per sample) including two water column profiles from the deeper basins were filtered (0.45 μm) and Nd and Hf were extracted and analysed following the accepted GEOTRACES protocols. The distribution patterns of the two elements and their isotopic compositions are compared to hydrographic data and oxygen measurements and provide information on sources and mixing of water masses, as well as on exchange processes with the underlying sediments, which are influenced by the prevailing redox gradients
Stochastic Kimura Equations
In this work we study the one-dimensional stochastic Kimura equation
for equipped with a Dirichlet boundary condition at , with
being a Gaussian space-time noise. This equation can be seen as a degenerate
analog of the parabolic Anderson model. We combine the Wiener chaos theory from
Malliavin calculus, the Duhamel perturbation technique from PDEs, and the
kernel analysis of (deterministic) degenerate diffusion equations to develop a
solution theory for the stochastic Kimura equation. We establish results on
existence, uniqueness, moments, and continuity for the solution
. In particular, we investigate how the stochastic potential
and the degeneracy in the diffusion operator jointly affect the properties of
near the boundary. We also derive explicit estimates on the
comparison under the norm between and its
deterministic counterpart for within a proper range.Comment: 45 page
Forecasting Housing Prices under Different Submarket Assumptions
This research evaluated forecasting accuracy of hedonic price models based on a number of different submarket assumptions. Using home sale data for the City of Knoxville and vicinities merged with geographic information, we found that forecasting housing prices with submarkets defined using expert knowledge and by school district and combining information conveyed in different modeling strategies are more accurate and efficient than models that are spatially aggregated, or with submarkets defined by statistical clustering techniques. This finding provided useful implications for housing price prediction in an urban setting and surrounding areas in that forecasting models based on expert knowledge of market structure or public school quality and simple model combining techniques may outperform the models using more sophisticated statistical techniques.Clustering, Forecasting, Hedonic price, Housing Submarket, Demand and Price Analysis, C53, R21,
Extracting Event Dynamics from Event-by-Event Analysis
The problem of eliminating the statistical fluctuations and extracting the
event dynamics from event-by-event analysis is discussed. New moments
(for continuous distribution), and (for anomalous distribution) are
proposed, which are experimentally measurable and can eliminate the Poissonian
type statistical fluctuations to recover the dynamical moments and
. In this way, the dynamical distribution of the event-averaged
transverse momentum \bar{\pt} can be extracted, and the anomalous scaling of
dynamical distribution, if exists, can be recovered, through event-by-event
analysis of experimental data.Comment: 15 pages, 2 eps figures, Phys. Rev. C accepte
Full-Field, Carrier-Less, Polarization-Diversity, Direct Detection Receiver based on Phase Retrieval
We realize dual-polarization full-field recovery using intensity only
measurements and phase retrieval techniques based on dispersive elements.
30-Gbaud QPSK waveforms are transmitted over 520-km standard single-mode fiber
and equalized from the receiver outputs using 2X2 MIMO
Limited profit in predictable stock markets
It has been assumed that arbitrage profits are not possible in efficient
markets, because future prices are not predictable. Here we show that
predictability alone is not a sufficient measure of market efficiency. We
instead propose to measure inefficiencies of markets in terms of the maximal
profit an ideal trader can take out from a market. In a stock market model with
an evolutionary selection of agents this method reveals that the mean relative
amount of realizable profits is very limited and we find that it decays
with rising number of agents in the markets. Our results show that markets may
self-organize their collective dynamics such that it becomes very sensitive to
profit attacks which demonstrates that a high degree of market efficiency can
coexist with predictability.Comment: 4 pages, 4 figure
Mass Spectrometry-based Methods for Phosphorylation Site Mapping of Hyperphosphorylated Proteins Applied to Net1, a Regulator of Exit from Mitosis in Yeast
Prior to anaphase in Saccharomyces cerevisiae, Cdc14 protein phosphatase is sequestered within the nucleolus and inhibited by Net1, a component of the RENT complex in budding yeast. During anaphase the RENT complex disassembles, allowing Cdc14 to migrate to the nucleus and cytoplasm where it catalyzes exit from mitosis. The mechanism of Cdc14 release appears to involve the polo-like kinase Cdc5, which is capable of promoting the dissociation of a recombinant Net1·Cdc14 complex in vitro by phosphorylation of Net1. We report here the phosphorylation site mapping of recombinant Net1 (Net1N) and a mutant Net1N allele (Net1N-19m) with 19 serines or threonines mutated to alanine. A variety of chromatographic and mass spectrometric-based strategies were used, including immobilized metal-affinity chromatography, alkaline phosphatase treatment, matrix-assisted laser-desorption post-source decay, and a multidimensional electrospray mass spectrometry-based approach. No one approach was able to identify all phosphopeptides in the tryptic digests of these proteins. Most notably, the presence of a basic residue near the phosphorylated residue significantly hampered the ability of alkaline phosphatase to hydrolyze the phosphate moiety. A major goal of research in proteomics is to identify all proteins and their interactions and post-translational modification states. The failure of any single method to identify all sites in highly phosphorylated Net1N, however, raises significant concerns about how feasible it is to map phosphorylation sites throughout the proteome using existing technologies
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