3,504 research outputs found
ALTKAL: An optimum linear filter for GEOS-3 altimeter data
ALTKAL is a computer program designed to smooth sea surface height data obtained from the GEOS 3 altimeter, and to produce minimum variance estimates of sea surface height and sea surface slopes, along with their standard derivations. The program operates by processing the data through a Kalman filter in both the forward and backward directions, and optimally combining the results. The sea surface height signal is considered to have a geoid signal, modeled by a third order Gauss-Markov process, corrupted by additive white noise. The governing parameters for the signal and noise processes are the signal correlation length and the signal-to-noise ratio. Mathematical derivations of the filtering and smoothing algorithms are presented. The smoother characteristics are illustrated by giving the frequency response, the data weighting sequence and the transfer function of a realistic steady-state smoother example. Based on nominal estimates for geoidal undulation amplitude and correlation length, standard deviations for the estimated sea surface height and slope are 12 cm and 3 arc seconds, respectively
A Class of Free Boundary Problems with Onset of a new Phase
A class of diffusion driven Free Boundary Problems is considered which is
characterized by the initial onset of a phase and by an explicit kinematic
condition for the evolution of the free boundary. By a domain fixing change of
variables it naturally leads to coupled systems comprised of a singular
parabolic initial boundary value problem and a Hamilton-Jacobi equation. Even
though the one dimensional case has been thoroughly investigated, results as
basic as well-posedness and regularity have so far not been obtained for its
higher dimensional counterpart. In this paper a recently developed regularity
theory for abstract singular parabolic Cauchy problems is utilized to obtain
the first well-posedness results for the Free Boundary Problems under
consideration. The derivation of elliptic regularity results for the underlying
static singular problems will play an important role
Case Report of Suspected Rhabdomyolysis during Treatment with Trabectedin in a Patient with Metastatic Leiomyosarcoma
Trabectedin has been reported to occasionally induce rhabdomyolysis. In the present case, continuation of trabectedin was maintained despite suspected rhabdomyolysis related to trabectedin. Creatinine kinase levels dropped to normal levels. We suggest that continuation of trabectedin despite suspected rhabdomyolysis was safe in this specific patient
Uniqueness of a Negative Mode About a Bounce Solution
We consider the uniqueness problem of a negative eigenvalue in the spectrum
of small fluctuations about a bounce solution in a multidimensional case. Our
approach is based on the concept of conjugate points from Morse theory and is a
natural generalization of the nodal theorem approach usually used in one
dimensional case. We show that bounce solution has exactly one conjugate point
at with multiplicity one.Comment: 4 pages,LaTe
Diversity and biomass dynamics of unicellular marine fungi during a spring phytoplankton bloom
Microbial communities have important functions during spring phytoplankton blooms, regulating bloom dynamics and processing organic matter. Despite extensive research into such processes, an in-depth assessment of the fungal component is missing, especially for the smaller size fractions. We investigated the dynamics of unicellular mycoplankton during a spring phytoplankton bloom in the North Sea by 18S rRNA gene tag sequencing and a modified CARD-FISH protocol. Visualization and enumeration of dominant taxa revealed unique cell count patterns that varied considerably over short time scales. The Rozellomycota sensu lato (s.l.) reached a maximum of 10(5) cells L-1, being comparable to freshwater counts. The abundance of Dikarya surpassed previous values by two orders of magnitude (10(5) cells L-1) and the corresponding biomass (maximum of 8.9 mg C m(-3)) was comparable to one reported for filamentous fungi with assigned ecological importance. Our results show that unicellular fungi are an abundant and, based on high cellular ribosome content and fast dynamics, active part of coastal microbial communities. The known ecology of the visualized taxa and the observed dynamics suggest the existence of different ecological niches that link primary and secondary food chains, highlighting the importance of unicellular fungi in food web structures and carbon transfer
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