Analyse komplexer Knochenbewegungen in Folgen von MRT Aufnahmen

Schädigungen des Bewegungsapparates können häufig nicht durch Auswertung von Einzelaufnahmen sondern nur durch Analyse der Bewegungsabläufe von Knochen diagnostiziert werden. Dies gilt beispielsweise für Schädigungen der Bänder bzw. Knorpel im Bereich des Kniegelenks, der Hals- und der Lendenwirbelsäule. In diesem Beitrag wird ein System zur Diagnose von Schädigungen des Bänderapparates der Handwurzelknochen vorgestellt (karpale Instabilitäten). Das Verfahren unterstützt insbesondere die Diagnose der nach Stürzen am häufigsten auftretenden 'Scapholunären Dissoziation', die bei einem Bänderriß zwischen dem Scaphoideum (Kahnbein) und dem Lunatum (Mondbein) sichtbar wird. Im Gegensatz beispielsweise zur Wirbelsäule führen die Handwurzelknochen Bewegungen um alle drei Raumachsen aus. Eine geeignete Schichtauswahl ermöglicht dennoch eine erfolgreiche Bewegungsvermessung mittels 2-D Analyse

Constraint Correlation Dynamics of SU(N) Gauge Theories

A constraint correlation dynamics up to 4-point Green functions is proposed for SU(N) gauge theories which reduces the N-body quantum field problem to the two-body level. The resulting set of nonlinear coupled equations fulfills all conservation laws including fermion number, linear and angular momenta as well as the total energy. Apart from the conservation laws in the space-time degrees of freedom the Gauss law is conserved as a quantum expectation value identically for all times. The same holds for the Ward identities as generated by commutators of Gauss operators. The constraint dynamical equations are highly non-perturbative and thus applicable also in the strong coupling regime, as e.g. low-energy QCD problems.Comment: 26 pages, LATEX, UGI-94-0

Selective Synthesis of Lysine Peptides and the Prebiotically Plausible Synthesis of Catalytically Active Diaminopropionic Acid Peptide Nitriles in Water

Why life encodes specific proteinogenic amino acids remains an unsolved problem, but a non-enzymatic synthesis that recapitulates biology's universal strategy of stepwise N-to-C terminal peptide growth may hold the key to this selection. Lysine is an important proteinogenic amino acid that, despite its essential structural, catalytic, and functional roles in biochemistry, has widely been assumed to be a late addition to the genetic code. Here, we demonstrate that lysine thioacids undergo coupling with aminonitriles in neutral water to afford peptides in near-quantitative yield, whereas non-proteinogenic lysine homologues, ornithine, and diaminobutyric acid cannot form peptides due to rapid and quantitative cyclization that irreversibly blocks peptide synthesis. We demonstrate for the first time that ornithine lactamization provides an absolute differentiation of lysine and ornithine during (non-enzymatic) N-to-C-terminal peptide ligation. We additionally demonstrate that the shortest lysine homologue, diaminopropionic acid, undergoes effective peptide ligation. This prompted us to discover a high-yielding prebiotically plausible synthesis of the diaminopropionic acid residue, by peptide nitrile modification, through the addition of ammonia to a dehydroalanine nitrile. With this synthesis in hand, we then discovered that the low basicity of diaminopropionyl residues promotes effective, biomimetic, imine catalysis in neutral water. Our results suggest diaminopropionic acid, synthesized by peptide nitrile modification, can replace or augment lysine residues during early evolution but that lysine's electronically isolated sidechain amine likely provides an evolutionary advantage for coupling and coding as a preformed monomer in monomer-by-monomer peptide translation

Covariant transport approach for strongly interacting partonic systems

The dynamics of partons, hadrons and strings in relativistic nucleus-nucleus collisions is analyzed within the novel Parton-Hadron-String Dynamics (PHSD) transport approach, which is based on a dynamical quasiparticle model for partons (DQPM) matched to reproduce recent lattice-QCD results - including the partonic equation of state - in thermodynamic equilibrium. Scalar- and vector-interaction densities are extracted from the DQPM as well as effective scalar- and vector-mean fields for the partons. The transition from partonic to hadronic degrees of freedom is described by covariant transition rates for the fusion of quark-antiquark pairs or three quarks (antiquarks), respectively, obeying flavor current-conservation, color neutrality as well as energy-momentum conservation. Since the dynamical quarks and antiquarks become very massive close to the phase transition, the formed resonant 'pre-hadronic' color-dipole states ($q\bar{q}$ or $qqq$) are of high invariant mass, too, and sequentially decay to the groundstate meson and baryon octets increasing the total entropy. When applying the PHSD approach to Pb+Pb colllisions at 158 A$\cdot$GeV we find a significant effect of the partonic phase on the production of multi-strange antibaryons due to a slightly enhanced $s{\bar s}$ pair production from massive time-like gluon decay and a larger formation of antibaryons in the hadronization process.Comment: 12 pages, 6 figures, to be published in the Proceedings of the 26th Winter Workshop on `Nuclear Dynamics', Ochto Rios, Jamaica, 2-9 January, 2010

Leading Transportation Indicators: Forecasting Waterborne Commerce Statistics Using Lock Performance Data

This paper develops and applies a forecasting model for transportation data based on the leading economic indicators literature. The specific application is to forecast river tonnages. Waterborne commerce data reflect tonnages of commodities moved on various rivers and in various directions. They are released after the Lock Performance Monitoring System data which reflect tonnages moving through specific locks. The model presented here forecasts waterborne commerce data from lock performance data. The results suggest that even a very simple model can provide precise forecasts

Composite Interstage Structural Concept Down Select Process and Results

NASA's Advanced Composites Technologies (ACT) project evaluated several composite construction options for the Ares V Interstage to support the Constellation Program's goal of reducing the mass of vehicle dry structures. In Phase 1 of the project, eight candidate construction concepts were evaluated for the Ares V Interstage design. Trade studies were performed using finite element analyses to determine weight estimates for the construction concepts. An evaluation process was then used to down select the construction concepts down to two concepts for further consideration in Phase 2 of the project. In Phase 2 of the project, additional trade studies were performed using detailed finite element analyses of the Interstage and a final down select process was used to choose the recommended Interstage construction concept. The results of the study showed that a honeycomb sandwich design was the most favorable Interstage construction concept based on advantages in manufacturing cost. Details of the Phase 1 and Phase 2 trade studies and down select process with final results are presented in the paper

The Quark-Gluon-Plasma Liquid

The quark-gluon plasma close to the critical temperature is a strongly interacting system. Using strongly coupled, classical, non-relativistic plasmas as an analogy, we argue that the quark-gluon plasma is in the liquid phase. This allows to understand experimental observations in ultrarelativistic heavy-ion collisions and to interpret lattice QCD results. It also supports the indications of the presence of a strongly coupled QGP in ultrarelativistic heavy-ion collisions.Comment: 8 pages, 2 figures, final version, to bepublished in J. Phys.

Stomatopoda (Crustacea: Hoplocarida) from the Shallow, Inshore Waters of the Northern Gulf of Mexico (Apalachicola River, Florida to Port Aransas, Texas)

Six species representing the order Stomatopoda are reported from the shallow, inshore waters (passes, bays, and estuaries) of the northern Gulf of Mexico limited to a depth of 10 m or less, and by the Apalachicola River (Florida) in the east and Port Aransas (Texas) in the west. With the exception of the “live bottom” gonodactylid, Neogonodactylus bredini (Manning), these predatory crustaceans usually inhabit burrows in mud, sand-mud, and sand substrata in coastal and shelf waters. The species treated in this paper are Neogonodactylus bredini (Manning), Lysiosquilla scabricauda (Lamarck), Bigelowina biminiensis (Bigelow), Coronis scolopendra Latreille, Squilla empusa Say, and Gibbesia neglecta (Gibbes). The questionable record of Squilla rugosa Bigelow by Archer (1948) is discussed. A review of the life history, ecology, distribution, and new northern Gulf of Mexico records is provided here for each of these species. Figures and an illustrated key are also presented