Studies of the effects of gravitational and inertial forces on cardiovascular and respiratory dynamics

The current status and application are described of the biplane video roentgen densitometry, videometry and video digitization systems. These techniques were developed, and continue to be developed for studies of the effects of gravitational and inertial forces on cardiovascular and respiratory dynamics in intact animals and man. Progress is reported in the field of lung dynamics and three-dimensional reconstruction of the dynamic thoracic contents from roentgen video images. It is anticipated that these data will provide added insight into the role of shape and internal spatial relationships (which is altered particularly by acceleration and position of the body) of these organs as an indication of their functional status

Application of NASTRAN for stress analysis of left ventricle of the heart

Knowing the stress and strain distributions in the left ventricular wall of the heart is a prerequisite for the determination of the muscle elasticity and contractility in the process of assessing the functional status of the heart. NASTRAN was applied for the calculation of these stresses and strains and to help in verifying the results obtained by the computer program FEAMPS which was specifically designed for the plane-strain finite-element analysis of the left ventricular cross sections. Adopted for the analysis are the true shape and dimensions of the cross sections reconstructed from multiplanar X-ray views of a left ventricle which was surgically isolated from a dog's heart but metabolically supported to sustain its beating. A preprocessor was prepared to accommodate both FEAMPS and NASTRAN, and it has also facilitated the application of both the triangular element and isoparameteric quadrilateral element versions of NASTRAN. The stresses in several crucial regions of the left ventricular wall calculated by these two independently developed computer programs are found to be in good agreement. Such confirmation of the results is essential in the development of a method which assesses the heart performance

Properties of D-mesons in nuclear matter within a self-consistent coupled-channel approach

The spectral density of the $D$-meson in the nuclear environment is studied within a self-consistent coupled-channel approach assuming a separable potential for the bare meson-baryon interaction. The $DN$ interaction, described through a G-matrix, generates dynamically the $\Lambda_c$ (2593) resonance. This resonance is the charm counterpart of the $\Lambda$ (1405) resonance generated from the s-wave $\bar{K}N$ interaction in the I=0 channel. The medium modification of the D-meson spectral density due to the Pauli blocking of intermediate states as well as due to the dressing of the D-mesons, nucleons and pions is investigated. We observe that the inclusion of coupled-channel effects and the self-consistent dressing of the $D$-meson results in an overall reduction of the in-medium $D$-meson changes compared to previous work which neglect those effects.Comment: 23 pages, 10 figures, submitted for publicatio

Intermediate energy Coulomb excitation as a probe of nuclear structure at radioactive beam facilities

The effects of retardation in the Coulomb excitation of radioactive nuclei in intermediate energy collisions (Elab ~100 MeV/nucleon) are investigated. We show that the excitation cross sections of low-lying states in 11Be, {38,40,42}S and {44,46}Ar projectiles incident on gold and lead targets are modified by as much as 20% due to these effects. The angular distributions of decaying gamma-rays are also appreciably modified.Comment: 21 pages, 3 figures, Phys. Rev. C, in pres

High precision measurement of the associated strangeness production in proton proton interactions

A new high precision measurement of the reaction pp -> pK+Lambda at a beam momentum of 2.95 GeV/c with more than 200,000 analyzed events allows a detailed analysis of differential observables and their inter-dependencies. Correlations of the angular distributions with momenta are examined. The invariant mass distributions are compared for different regions in the Dalitz plots. The cusp structure at the N Sigma threshold is described with the Flatt\'e formalism and its variation in the Dalitz plot is analyzed.Comment: accepted for publication in Eur. Phys. J.

First Model-Independent Measurement of the Spin Triplet pΛp\Lambda Scattering Length from Final State Interaction in the p⃗p→pK+Λ\vec{p}p \rightarrow pK^{+}\Lambda Reaction

The $\vec{p}p \rightarrow pK^{+}\Lambda$ reaction has been measured with the COSY-TOF detector at a beam momentum of $2.7\,\mathrm{GeV}/c$. The polarized proton beam enables the measurement of the beam analyzing power by the asymmetry of the produced kaon ($A_N^{K}$). This observable allows the $p\Lambda$ spin triplet scattering length to be extracted for the first time model independently from the final-state interaction in the reaction. The obtained value is $a_{t} = (-2.55 ^{+0.72}_{-1.39} {}_{\textrm{stat.}} \pm 0.6_{\textrm{syst.}} \pm 0.3_{\textrm{theo.}})\mathrm{fm}$. This value is compatible with theoretical predictions and results from model-dependent analyses.Comment: Revised version as accepted for publication in PR

Search for the 3He-eta bound state at COSY-11

We have measured excitation function for dp -> ppp_pi- reaction near the eta production threshold. We observe an enhancement of the counting rate above the threshold which can originate from the production of the eta meson in the reaction dp -> 3He eta and its subsequent absorption on neutron in the 3He nucleus leading to creation of the p_pi- pair.Comment: Presented at 10th International Workshop on Meson Production, Properties and Interaction (MESON 2008), Cracow, Poland, 6 - 10 June 2008, 4 pages, 4 figures,references adde

The Straw Tube Trackers of the PANDA Experiment

The PANDA experiment will be built at the FAIR facility at Darmstadt (Germany) to perform accurate tests of the strong interaction through bar pp and bar pA annihilation's studies. To track charged particles, two systems consisting of a set of planar, closed-packed, self-supporting straw tube layers are under construction. The PANDA straw tubes will have also unique characteristics in term of material budget and performance. They consist of very thin mylar-aluminized cathodes which are made self-supporting by means of the operation gas-mixture over-pressure. This solution allows to reduce at maximum the weight of the mechanical support frame and hence the detector material budget. The PANDA straw tube central tracker will not only reconstruct charged particle trajectories, but also will help in low momentum (< 1 GeV) particle identification via dE/dx measurements. This is a quite new approach that PANDA tracking group has first tested with detailed Monte Carlo simulations, and then with experimental tests of detector prototypes. This paper addresses the design issues of the PANDA straw tube trackers and the performance obtained in prototype tests.Comment: 7 pages,16 figure

Ultra high-speed transaxial image reconstruction of the heart, lungs, and circulation via numerical approximation methods and optimized processor architecture

A high temporal resolution scanning multiaxial tomography unit, the Dynamic Spatial Reconstructor (DSR), presently under development will be capable of recording multiangular X-ray projection data of sufficient axial range to reconstruct a cylindrical volume consisting of up to 240 contiguous 1-mm thick cross sections encompassing the intact thorax. At repetition rates of up to 60 sets of cross sections per second, the DSR will thus record projection data sufficient to reconstruct as many as 14 400 cross-sectional images during each second of operation. Use of this system in a clinical setting will be dependent upon the development of software and hardware techniques for carrying out X-ray reconstructions at the rate of hundreds of cross sections per second. A conceptual design, with several variations, is proposed for a special purpose hardware reconstruction processor capable of completing a single cross section reconstruction within 1 to 2 msec. In addition, it is suggested that the amount of computation required to execute the filtered back-projection algorithm may be decreased significantly by the utilization of approximation equations, formulated as recursions, for the generation of internal constants required by the algorithm. The effects on reconstructed image quality of several different approximation methods are investigated by reconstruction of density projections generated from a mathematically simulated model of the human thorax, assuming the same source-detector geometry and X-ray flux density as will be employed by the DSR. These studies have indicated that the prudent application of numerical approximations for the generation of internal constants will not cause significant degradation in reconstructed image quality and will in fact require substantially less auxiliary memory and computational capacity than required by direct execution of mathematically exact formulations of the reconstruction algorithm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23631/1/0000595.pd

Probing the nuclear equation of state by K+K^+ production in heavy ion collisions

The dependence of $K^+$ production on the nuclear equation of state is investigated in heavy ion collisions. An increase of the excitation function of $K^+$ multiplicities obtained in heavy ($Au+Au$) over light ($C+C$) systems when going far below threshold which has been observed by the KaoS Collaboration strongly favours a soft equation of state. This observation holds despite of the influence of an in-medium kaon potential predicted by effective chiral models which is necessary to reproduce the experimental $K^+$ yields.Comment: 4 pages Revtex, 4 PS figures, to appear in Phys. Rev. Let