Relativistic eikonal description of A(p,pN) reactions

The authors present a relativistic and cross-section factorized framework for computing quasielastic A(p,pN) observables at intermediate and high energies. The model is based on the eikonal approximation and can accomodate both optical potentials and the Glauber method for dealing with the initial- and final-state interactions (IFSI). At lower nucleon energies, the optical-potential philosophy is preferred, whereas at higher energies the Glauber method is more natural. This versatility in dealing with the IFSI allows one to describe A(p,pN) reactions in a wide energy range. Most results presented here use optical potentials as this approach is argued to be the optimum choice for the kinematics of the experiments considered in the present paper. The properties of the IFSI factor, a function wherein the entire effect of the IFSI is contained, are studied in detail. The predictions of the presented framework are compared with two kinematically different experiments. First, differential cross sections for quasielastic proton scattering at 1 GeV off 12C, 16O, and 40Ca target nuclei are computed and compared to data from PNPI. Second, the formalism is applied to the analysis of a 4He(p,2p) experiment at 250 MeV. The optical-potential calculations are found to be in good agreement with the data from both experiments, showing the reliability of the adopted model in a wide energy range.Comment: 34 pages, 14 figures, accepted for publication in Phys. Rev.

Measurement of tensor analyzing powers in deuteron photodisintegration

New accurate measurement of tensor analyzing powers T20, T21 and T22 in deuteron photodisintegration has been performed. Wide-aperture non-magnetic detectors allowed to cover broad kinematic ranges in a single setup: photon energy = 25 to 600 MeV, proton emission angle in CM = 24 to 48 deg. and 70 to 102 deg. New data provide a significant improvement of a few existing measurements. The angular dependency of the tensor asymmetries in deuteron photodisintegration is extracted for the first time.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let

Probing coherent charmonium photoproduction off light nuclei at medium energies

We demonstrate how the elementary amplitudes $\gamma N\to \Psi N$, the amplitude of the nondiagonal $J/\psi N\Leftrightarrow \psi' N$ transition, and the total $J/\psi N$ and $\psi' N$ cross sections can be determined from measurements of the coherent $J/\psi$ and $\psi'$ photoproduction off light nuclei at moderate energies. For this purpose we provide a detailed numerical analysis of the coherent charmonium photoproduction off silicon within the generalized vector dominance model (GVDM) adjusted to account for the physics of charmonium models and color transparency phenomenon.Comment: 8 pages, 5 figures (color

Radio-frequency discharges in Oxygen. Part 1: Modeling

In this series of three papers we present results from a combined experimental and theoretical effort to quantitatively describe capacitively coupled radio-frequency discharges in oxygen. The particle-in-cell Monte-Carlo model on which the theoretical description is based will be described in the present paper. It treats space charge fields and transport processes on an equal footing with the most important plasma-chemical reactions. For given external voltage and pressure, the model determines the electric potential within the discharge and the distribution functions for electrons, negatively charged atomic oxygen, and positively charged molecular oxygen. Previously used scattering and reaction cross section data are critically assessed and in some cases modified. To validate our model, we compare the densities in the bulk of the discharge with experimental data and find good agreement, indicating that essential aspects of an oxygen discharge are captured.Comment: 11 pages, 10 figure

The effect of the FODMAP and rebamipid diet on the activity of disaccharidases in patients with enteropathy with impaired membrane digestion

Aim. To compare the effect of a diet low in fermentable oligo-, di-, monosaccharides and polyols (fermentable oligosaccharides, disaccharides, monosaccharides and polyols FODMAP) and rebamipide on carbohydrate tolerance and disaccharidases activity in patients with maldigestive enteropathy (ENMP). Materials and methods. The study included 61 patients with ENMP with reduced small intestine carbohydrases. Their glucoamylase activity was 100 ng glucose/mg tissue min (quartile 53, 72), maltase 504 (quartile 258, 708), sucrase 43 (quartile 25, 58), lactase 8 (quartile 4, 20). Group 1 included 19 people on a low FODMAP diet. The 2nd group included 42 patients who were on a normal diet and received rebamipide 300 mg/day. Patients were monitored weekly for 8 weeks. Results. In 16 patients of the 1st group, abdominal pain and stool disorders decreased, in 15 patients, swelling and rumbling in the abdomen stopped. Glucoamylase activity increased to 196 (quartile 133, 446, р0.024) ng glucose/mg tissue min, maltase activity increased to 889 (quartile 554, 1555, p0.145), sucrase activity increased to 67 (quartile 43, 175, p0.039), lactase activity increased to 13 (quartile 9, 21, p0.02). After the diet was discontinued, intestinal symptoms in patients of group 1 resumed. In 27 patients of the 2nd group after 4 weeks dyspeptic manifestations decreased, in 34 patients the tolerability of products containing FODMAP improved. Continuation of treatment up to 8 weeks contributed to a further improvement in well-being. Glucoamylase activity increased after 4 and 8 weeks to 189 (quartile 107, 357, p0.013) and 203 (quartile 160, 536, p0.005), respectively; maltase up to 812 (quartile 487, 915, p0.005) and 966 (quartile 621, 2195, р0.0012); sucrases up to 60 (quartile 34, 105, p0.013) and 75 (quartile 52, 245, р=0.003); lactase up to 12 (quartile 8, 12, p0.132) and 15 ng glucose/mg tissue min (quartile 10, 20, р0.092). Conclusion. The clinical symptoms of fermentable carbohydrate intolerance and increased membrane enzyme activity are reduced by a low FODMAP diet in patients with ENMT, but clinical symptoms of food intolerance reappear when switching to a normal diet. Treatment with rebamipide improves food tolerance and consistently increases the activity of TSOTS enzymes after 4 and 8 weeks

Measurement of Angular Distributions and R= sigma_L/sigma_T in Diffractive Electroproduction of rho^0 Mesons

Production and decay angular distributions were extracted from measurements of exclusive electroproduction of the rho^0(770) meson over a range in the virtual photon negative four-momentum squared 0.5< Q^2 <4 GeV^2 and the photon-nucleon invariant mass range 3.8< W <6.5 GeV. The experiment was performed with the HERMES spectrometer, using a longitudinally polarized positron beam and a ^3He gas target internal to the HERA e^{+-} storage ring. The event sample combines rho^0 mesons produced incoherently off individual nucleons and coherently off the nucleus as a whole. The distributions in one production angle and two angles describing the rho^0 -> pi+ pi- decay yielded measurements of eight elements of the spin-density matrix, including one that had not been measured before. The results are consistent with the dominance of helicity-conserving amplitudes and natural parity exchange. The improved precision achieved at 47 GeV, reveals evidence for an energy dependence in the ratio R of the longitudinal to transverse cross sections at constant Q^2.Comment: 15 pages, 15 embedded figures, LaTeX for SVJour(epj) document class Revision: Fig. 15 corrected, recent data added to Figs. 10,12,14,15; minor changes to tex

Nuclear Polarization of Molecular Hydrogen Recombined on a Non-metallic Surface

The nuclear polarization of $\mathrm{H}_2$ molecules formed by recombination of nuclear polarized H atoms on the surface of a storage cell initially coated with a silicon-based polymer has been measured by using the longitudinal double-spin asymmetry in deep-inelastic positron-proton scattering. The molecules are found to have a substantial nuclear polarization, which is evidence that initially polarized atoms retain their nuclear polarization when absorbed on this type of surfac

Fluorescence-Tagged Transgenic Lines Reveal Genetic Defects in Pollen Growth—Application to the Eif3 Complex

BACKGROUND: Mutations in several subunits of eukaryotic translation initiation factor 3 (eIF3) cause male transmission defects in Arabidopsis thaliana. To identify the stage of pollen development at which eIF3 becomes essential it is desirable to examine viable pollen and distinguish mutant from wild type. To accomplish this we have developed a broadly applicable method to track mutant alleles that are not already tagged by a visible marker gene through the male lineage of Arabidopsis. METHODOLOGY/PRINCIPAL FINDINGS: Fluorescence tagged lines (FTLs) harbor a transgenic fluorescent protein gene (XFP) expressed by the pollen-specific LAT52 promoter at a defined chromosomal position. In the existing collection of FTLs there are enough XFP marker genes to track nearly every nuclear gene by virtue of its genetic linkage to a transgenic marker gene. Using FTLs in a quartet mutant, which yields mature pollen tetrads, we determined that the pollen transmission defect of the eif3h-1 allele is due to a combination of reduced pollen germination and reduced pollen tube elongation. We also detected reduced pollen germination for eif3e. However, neither eif3h nor eif3e, unlike other known gametophytic mutations, measurably disrupted the early stages of pollen maturation. CONCLUSION/SIGNIFICANCE: eIF3h and eIF3e both become essential during pollen germination, a stage of vigorous translation of newly transcribed mRNAs. These data delimit the end of the developmental window during which paternal rescue is still possible. Moreover, the FTL collection of mapped fluorescent protein transgenes represents an attractive resource for elucidating the pollen development phenotypes of any fine-mapped mutation in Arabidopsis

Transcriptome analysis of haploid male gametophyte development in Arabidopsis

BACKGROUND: The haploid male gametophyte generation of flowering plants consists of two- or three-celled pollen grains. This functional specialization is thought to be a key factor in the evolutionary success of flowering plants. Moreover, pollen ontogeny is also an attractive model in which to dissect cellular networks that control cell growth, asymmetric cell division and cellular differentiation. Our objective, and an essential step towards the detailed understanding of these processes, was to comprehensively define the male haploid transcriptome throughout development. RESULTS: We have developed staged spore isolation procedures for Arabidopsis and used Affymetrix ATH1 genome arrays to identify a total of 13,977 male gametophyte-expressed mRNAs, 9.7% of which were male-gametophyte-specific. The transition from bicellular to tricellular pollen was accompanied by a decline in the number of diverse mRNA species and an increase in the proportion of male gametophyte-specific transcripts. Expression profiles of regulatory proteins and distinct clusters of coexpressed genes were identified that could correspond to components of gametophytic regulatory networks. Moreover, integration of transcriptome and experimental data revealed the early synthesis of translation factors and their requirement to support pollen tube growth. CONCLUSIONS: The progression from proliferating microspores to terminally differentiated pollen is characterized by large-scale repression of early program genes and the activation of a unique late gene-expression program in maturing pollen. These data provide a quantum increase in knowledge concerning gametophytic transcription and lay the foundations for new genomic-led studies of the regulatory networks and cellular functions that operate to specify male gametophyte development