786 research outputs found
Polarization phenomena in the reaction NN to NNpi near threshold
First calculations for spin-dependent observables of the reactions , and near threshold are presented,
employing the J\"ulich model for pion production. The influence of resonant
(via the excitation of the ) and non-resonant p-wave pion
production mechanisms on these observables is examined. For the reactions and nice agreement of our predictions with the
presently available data on spin correlation coefficents is observed whereas
for the description of the data is less satisfying.Comment: 10 pages, 4 figure
Expression of Guanylyl Cyclase (GC)-A and GC-B during Brain Development: Evidence for a Role of GC-B in Perinatal Neurogenesis
Atrial (ANP) and C-type (CNP) natriuretic peptide generate physiological effects via selective activation of two closely related membrane receptors with guanylyl cyclase (GC) activity, known as GC-A and GC-B. As yet, however, the discrete roles for ANP/GC-A vs. CNP/GC-B signaling in many mammalian tissues are still poorly understood. We here used receptor affinity labeling and GC assays to characterize comparatively GC-A/GC-B expression and functional activity during rat brain development. The study revealed that GC-B predominates in the developing and GC-A in the adult brain, with regional differences each between cerebral cortex, cerebellum, and brain stem. Whereas GC-A levels nearly continuously increase between embryonal d 18 and adult, GC-B expression in brain is highest and widely distributed around postnatal d 1. The striking perinatal GC-B peak coincides with elevated expression of nestin, a marker protein for neural stem/progenitor cells. Immunohistochemical investigations revealed a cell body-restricted subcellular localization of GC-B and perinatal abundance of GC-B-expressing cells in regions high in nestin-expressing cells. However, and supported by examination of nestin-GFP transgenic mice, GC-B and nestin are not coexpressed in the same cells. Rather, GC-B(+) cells are distinguished by expression of NeuN, an early marker of differentiating neurons. These findings suggest that GC-B(+) cells represent neuronal fate-specific progeny of nestin(+) progenitors and raise the attention to specific and pronounced activities of CNP/GC-B signaling during perinatal brain maturation. The absence of this activity may cause the neurological disorders observed in GC-B-deficient mice
Pion-nucleon scattering in a meson-exchange model
The pi-N interaction is studied within a meson-exchange model and in a
coupled-channels approach which includes the channels pi-N, eta-N, as well as
three effective pi-pi-N channels namely rho-N, pi-Delta, and sigma-N. Starting
out from an earlier model of the Julich group systematic improvements in the
dynamics and in some technical aspects are introduced. With the new model an
excellent quantitative reproduction of the pi-N phase shifts and inelasticity
parameters in the energy region up to 1.9 GeV and for total angular momenta J
leq 3/2 is achieved. Simultaneously, good agreement with data for the total and
differential pi-N -> eta-N transition cross sections is obtained. The
connection of the pi_N dynamics in the S_{11} partial wave with the reaction
pi-N -> eta-N is discussed.Comment: 32 pages, 9 figure
Angular asymmetries in the reactions pp \to d\pi^+\eta and pn \to d\pi^0\eta and a_0-f_0 mixing
The reactions pp\to d\pi^+\eta and pn\to d\pi^0\eta are of special interest
for investigating the a_0(980) (J^P=0^+) resonance in the process NN \to da_0
\to d\pi\eta. We study some aspects of those reactions within a general
formalism and also in a concrete phenomenological model. In particular, it is
shown that the presence of nonresonant (i.e. without excitation of the a_0
resonance) contributions to these reactions yields nonvanishing values for
specific polarization observables, i.e. to effects like those generated by
a_0-f_0 mixing. An experimental determination of these observables for the
reaction pp\to d\pi^+\eta would provide concrete information on the magnitude
of those nonresonant contributions to \pi\eta production. We discuss also the
possibility of extracting information about a_0-f_0 mixing from the reaction pn
\to d\pi^0\eta with polarized proton beam.Comment: 14 pages, 3 figure
Evaluation of a novel mitochondrial Pan-Mucorales marker for the detection, identification, quantification, and growth stage determination of mucormycetes
Mucormycosis infections are infrequent yet aggressive and serious fungal infections. Early diagnosis of mucormycosis and its discrimination from other fungal infections is required for targeted treatment and more favorable patient outcomes. The majority of the molecular assays use 18 S rDNA. In the current study, we aimed to explore the potential of the mitochondrial rnl (encoding for large-subunit-ribosomal-RNA) gene as a novel molecular marker suitable for research and diagnostics. Rnl was evaluated as a marker for: (1) the Mucorales family, (2) species identification (Rhizopus arrhizus, R. microsporus, Mucor circinelloides, and Lichtheimia species complexes), (3) growth stage, and (4) quantification. Sensitivity, specificity, discriminatory power, the limit of detection (LoD), and cross-reactivity were evaluated. Assays were tested using pure cultures, spiked clinical samples, murine organs, and human paraffin-embedded-tissue (FFPE) samples. Mitochondrial markers were found to be superior to nuclear markers for degraded samples. Rnl outperformed the UMD universal® (Molyzm) marker in FFPE (71.5% positive samples versus 50%). Spiked blood samples highlighted the potential of rnl as a pan-Mucorales screening test. Fungal burden was reproducibly quantified in murine organs using standard curves. Identification of pure cultures gave a perfect (100%) correlation with the detected internal transcribed spacer (ITS) sequence. In conclusion, mitochondrial genes, such as rnl, provide an alternative to the nuclear 18 S rDNA genes and deserve further evaluation.CD laboratory: This research was funded by the Christian Doppler Laboratory for fungal infections
Meson model for f_0(980) production in peripheral pion-nucleon reactions
The Juelich model for pion-pion-scattering, based on an effective meson-meson
Lagrangian is applied to the analysis of the S-wave production amplitudes
derived from the BNL E852 experiment pi^- p -> pi^0 pi^0 n for a pion momentum
of 18.3 GeV. The unexpected strong dependence of the S-wave partial wave
amplitude on the momentum transfer between the proton and neutron in the
vicinity of the f_0(980) resonance is explained in our analysis as interference
effect between the correlated and uncorrelated pi^0 pi^0 pairs.Comment: 6 pages, 7 figures, formulas added, typos removed, new figure
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