283 research outputs found

    Investigation of Parietal Polysaccharides from Retama raetam Roots

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    This study characterizes the cell wall hemicellulose and pectins polymers of Retama raetam. This species develops a particularly important root system and is adapted to arid areas. The cellulose, hemicelluloses and pectins were extracted. The cellulose remains the major component of the wall (27% for young roots and 80% for  adult roots), hemicelluloses (14.3% for young roots and 3.6%  for adult roots) and pectins (17.3% for young roots and 4.1% for adult roots). The monosaccharidic composition of water soluble extracts determined by gas liquid chromatography (GLC) and completed by infrared (FTIR) spectroscopy of hemicellulosic shows the presence of xylose as a major monosaccharide in the non-cellulose polysaccharides (47.8% for young roots and 59.5% for adult roots). These results indicate the presence of the homogalacturonans and rhamnogalacturonans in pectin. This study constitutes the preliminary data obtained in the biochemical analysis of the parietal compounds of the roots of a species which grows in an arid area in comparison with those of its aerial parts.Keywords: Retama raetam, Roots, Cell Wall, Investigation, Polysaccharides, Monosaccharidi

    8Be cluster emission versus alpha evaporation in 28Si + 12C

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    The possible occurence of highly deformed configurations in the 40^{40}Ca di-nuclear system formed in the 28^{28}Si + 12^{12}C reaction is investigated by analyzing the spectra of emitted light charged particles. Both inclusive and exclusive measurements of the heavy fragments (A ≥\geq 10) and their associated light charged particles (protons and α\alpha particles) have been made at the IReS Strasbourg {\sc VIVITRON} Tandem facility at bombarding energies of ElabE_{lab} (28^{28}Si) = 112 MeV and 180 MeV by using the {\sc ICARE} charged particle multidetector array. The energy spectra, velocity distributions, in-plane and out-of-plane angular correlations of light charged particles are compared to statistical-model calculations using a consistent set of parameters with spin-dependent level densities. This spin dependence approach suggests the onset of large nuclear deformation in 40^{40}Ca at high spin. This conclusion might be connected with the recent observation of superdeformed bands in the 40^{40}Ca nucleus. The analysis of α\alpha particles in coincidence with 32^{32}S fragments suggests a surprisingly strong 8^{8}Be cluster emission of a binary nature.Comment: 39 pages 15 figure

    Search for emission of unstable 8^8Be clusters from hot 40^40Ca and 56^56Ni nuclei

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    The possible occurence of highly deformed configurations is investigated in the 40^{40}Ca and 56^{56}Ni di-nuclear systems as formed in the 28^{28}Si + 12^{12}C and 28^{28}Si + 28^{28}Si reactions, respectively, by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy fragments (A ≥\geq 6) and their associated light charged particles (p, d, t, and α\alpha-particles) have been collected at the IReS Strasbourg VIVITRON Tandem facility with two bombarding energies Elab(28E_{lab}(^{28}Si) = 112 and 180 MeV by using the ICARE charged particle multidetector array, which consists of nearly 40 telescopes. The measured energy spectra, velocity distributions, in-plane and out-of-plane angular correlations are analysed by Monte Carlo CASCADE statistical-model calculations using a consistent set of parameters with spin-dependent level densities. Although significant deformation effects at high spin are needed, the remaining disagreement observed in the 28^{28}Si + 12^{12}C reaction for the S evaporation residue suggests an unexpected large unstable 8^{8}Be cluster emission of a binary nature.Comment: 13 pages latex, 9 eps figures. Paper presented at the XXXIX International Winter Meeting on Nuclear Physics, Bormio(Italy) January 22-27, 2001 (to be published at Ricerca Scientifica ed Educazione Permanente

    Large Deformation Effects in the N = Z 44Ti Compound Nucleus

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    The N = Z 44Ti* nucleus has been populated in Fusion Evaporation process at very high excitation energies and angular momenta using two entrance channels with different mass-asymmetry. The deformation effects in the rapidly rotating nuclei have been investigated through the energy distribution of the alpha-particle combined to statistical-model calculations. In the case of low-multiplicity events, the ratio between first particle emitted has been measured and shows significant disagreement with the predictions of the statistical-model. This may explain The large discrepancies observed in proton energy spectra measured in previous experiments performed in the same mass region.Comment: Proceeding of the 10th International Conference on Nuclear Reaction Mechanisms, Varenna Italy, June 9-13 2003. 10 pages, 6 figures, 1 tabl

    Deformation effects in the 28^{28}Si+12^{12}C and 28^{28}Si+28^{28}Si reaction Search

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    The possible occurence of highly deformed configurations is investigated in the 40^{40}Ca and 56^{56}Ni di-nuclear systems as formed in the 28^{28}Si+12^{12}C,28^{28}Si reactions by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy fragments and their associated light charged particles have been collected by using the {\sc ICARE} charged particle multidetector array. The data are analysed by Monte Carlo CASCADE statistical-model calculations using a consistent set of parameters with spin-dependent level densities. Significant deformation effects at high spin are observed as well as an unexpected large 8^{8}Be cluster emission of a binary nature.Comment: 3 pages latex, 2 eps figures, paper presented in "wokshop on physics with multidetector array (pmda2000)Calcutta, India (to be published at PRAMANA, journal of Physics, India

    Clinical practice guidelines for laboratory diagnosis of epidermolysis bullosa

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    This guideline were initiated by DEBRA International; financial support was provided by DEBRA Austria. The generous assistance of Rebecca Bodan, Lisa Brains, Sharon Cassidy and Kelsey Townsend-Miller is gratefully acknowledged in providing patient or lay input into this guideline. The authors acknowledge the guidance of Kattya Mayre-Chilton (DEDRA International). Johann Bauer (Paracelsus University and EB House, Salzburg, Austria), Christine Bodemer (HĂ´pital Universitaire Necker, Paris, France), Judith Fischer (Institute of Human Genetics, University of Freiburg, Germany), Jemima Mellerio (St John's Institute of Dermatology, Guy's and St Thomas' NHS Foundation Trust, London, U.K.), Francis Palisson (Universidad del Desarrollo and DEBRA, Chile), Eli Sprecher (Department of Dermatology, Tel Aviv Sourasky Medical Center, Israel) and Jouni Uitto, Leila Youssefian and Hassan Vahidnezhad (all from the Department of Dermatology and Cutaneous Biology, Thomas Jefferson University, Philadelphia, PA, U.S.A.) are acknowledged as reviewers

    Deformation effects in 56^{56}Ni nuclei produced in 28^{28}Si+28^{28}Si at 112 MeV

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    Velocity and energy spectra of the light charged particles (protons and α\alpha-particles) emitted in the 28^{28}Si(Elab_{lab} = 112 MeV) + 28^{28}Si reaction have been measured at the Strasbourg VIVITRON Tandem facility. The ICARE charged particle multidetector array was used to obtain exclusive spectra of the light particles in the angular range 15 - 150 degree and to determine the angular correlations of these particles with respect to the emission angles of the evaporation residues. The experimental data are analysed in the framework of the statistical model. The exclusive energy spectra of α\alpha-particles emitted from the 28^{28}Si + 28^{28}Si compound system are generally well reproduced by Monte Carlo calculations using spin-dependent level densities. This spin dependence approach suggests the onset of large deformations at high spin. A re-analysis of previous α\alpha-particle data from the 30^{30}Si + 30^{30}Si compound system, using the same spin-dependent parametrization, is also presented in the framework of a general discussion of the occurrence of large deformation effects in the ACN_{CN} ~ 60 mass region.Comment: 25 pages, 6 figure

    Vanishing spin alignment : experimental indication of triaxial 28Si+28Si\bf ^{28}Si + {^{28}Si} nuclear molecule

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    Fragment-fragment-Îł\gamma coincidences have been measured for 28Si+28Si\rm ^{28}Si + {^{28}Si} at an energy corresponding to the population of a conjectured resonance in 56^{56}Ni. Fragment angular distributions as well as Îł\gamma-ray angular correlations indicate that the spin orientations of the outgoing fragments are perpendicular to the orbital angular momentum. This differs from the 24Mg+24Mg\rm ^{24}Mg+{^{24}Mg} and the 12C+12C\rm ^{12}C+{^{12}C} resonances, and suggests two oblate 28Si\rm ^{28}Si nuclei interacting in an equator-to-equator molecular configuration.Comment: 14 pages standard REVTeX file, 3 ps Figures -- Accepted for publication in Physical Review C (Rapid Communication

    Highly deformed 40^{40}Ca configurations in 28^{28}Si + 12^{12}C

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    The possible occurrence of highly deformed configurations in the 40^{40}Ca di-nuclear system formed in the 28^{28}Si + 12^{12}C reaction is investigated by analyzing the spectra of emitted light charged particles. Both inclusive and exclusive measurements of the heavy fragments (A ≥\geq 10) and their associated light charged particles (protons and α\alpha particles) have been made at the IReS Strasbourg {\sc VIVITRON} Tandem facility at bombarding energies of Elab(28E_{lab} (^{28}Si) = 112 MeV and 180 MeV by using the {\sc ICARE} charged particle multidetector array. The energy spectra, velocity distributions, and both in-plane and out-of-plane angular correlations of light charged particles are compared to statistical-model calculations using a consistent set of parameters with spin-dependent level densities. The analysis suggests the onset of large nuclear deformation in 40^{40}Ca at high spin.Comment: 33 pages, 11 figure

    On the Transmit Beamforming for MIMO Wiretap Channels: Large-System Analysis

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    With the growth of wireless networks, security has become a fundamental issue in wireless communications due to the broadcast nature of these networks. In this work, we consider MIMO wiretap channels in a fast fading environment, for which the overall performance is characterized by the ergodic MIMO secrecy rate. Unfortunately, the direct solution to finding ergodic secrecy rates is prohibitive due to the expectations in the rates expressions in this setting. To overcome this difficulty, we invoke the large-system assumption, which allows a deterministic approximation to the ergodic mutual information. Leveraging results from random matrix theory, we are able to characterize the achievable ergodic secrecy rates. Based on this characterization, we address the problem of covariance optimization at the transmitter. Our numerical results demonstrate a good match between the large-system approximation and the actual simulated secrecy rates, as well as some interesting features of the precoder optimization.Comment: Published in Lecture Notes in Computer Science 8317, pp. 90-102, 2014. (Proceedings of International Conference on Information-Theoretic Security (ICITS), Singapore, November 2013
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