528 research outputs found

    Pleosporales

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    One hundred and five generic types of Pleosporales are described and illustrated. A brief introduction and detailed history with short notes on morphology, molecular phylogeny as well as a general conclusion of each genus are provided. For those genera where the type or a representative specimen is unavailable, a brief note is given. Altogether 174 genera of Pleosporales are treated. Phaeotrichaceae as well as Kriegeriella, Zeuctomorpha and Muroia are excluded from Pleosporales. Based on the multigene phylogenetic analysis, the suborder Massarineae is emended to accommodate five families, viz. Lentitheciaceae, Massarinaceae, Montagnulaceae, Morosphaeriaceae and Trematosphaeriaceae

    Evidence for a Soft Nuclear Equation-of-State from Kaon Production in Heavy Ion Collisions

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    The production of pions and kaons has been measured in Au+Au collisions at beam energies from 0.6 to 1.5 AGeV with the Kaon Spectrometer at SIS/GSI. The K+ meson multiplicity per nucleon is enhanced in Au+Au collisions by factors up to 6 relative to C+C reactions whereas the corresponding pion ratio is reduced. The ratio of the K+ meson excitation functions for Au+Au and C+C collisions increases with decreasing beam energy. This behavior is expected for a soft nuclear equation-of-state.Comment: 14 pages, 2 figures, accepted for publication in Phys. Rev. Let

    Production of Charged Pions, Kaons and Antikaons in Relativistic C+C and C+Au Collisions

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    Production cross sections of charged pions, kaons and antikaons have been measured in C+C and C+Au collisions at beam energies of 1.0 and 1.8 AGeV for different polar emission angles. The kaon and antikaon energy spectra can be described by Boltzmann distributions whereas the pion spectra exhibit an additional enhancement at low energies. The pion multiplicity per participating nucleon M(pi+)/A_part is a factor of about 3 smaller in C+Au than in C+C collisions at 1.0 AGeV whereas it differs only little for the C and the Au target at a beam energy of 1.8 AGeV. The K+ multiplicities per participating nucleon M(K+)/A_part are independent of the target size at 1 AGeV and at 1.8 AGeV. The K- multiplicity per participating nucleon M(K-)/A_part is reduced by a factor of about 2 in C+Au as compared to C+C collisions at 1.8 AGeV. This effect might be caused by the absorption of antikaons in the heavy target nucleus. Transport model calculations underestimate the K-/K+ ratio for C+C collisions at 1.8 AGeV by a factor of about 4 if in-medium modifications of K mesons are neglected.Comment: 19 pages, 14 figures, accepted for publication in Eur. Phys. J.

    Evidence for Different Freeze-Out Radii of High- and Low-Energy Pions Emitted in Au+Au Collisions at 1 GeV/nucleon

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    Double differential production cross sections of negative and positive pions and the number of participating protons have been measured in central Au+Au collisions at 1 GeV per nucleon incident energy. At low pion energies the pi^- yield is strongly enhanced over the pi^+ yield. The energy dependence of the pi^-/pi^+ ratio is assigned to the Coulomb interaction of the charged pions with the protons in the reaction zone. The deduced Coulomb potential increases with increasing pion c.m. energy. This behavior indicates different freeze-out radii for different pion energies in the c.m.~frame.Comment: IKDA is the Institute for Nuclear Physics in Darmstadt/German

    Enhanced Out-of-plane Emission of K+ Mesons observed in Au+Au Collisions at 1 AGeV

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    The azimuthal angular distribution of K+ mesons has been measured in Au + Au collisions at 1 AGeV. In peripheral and semi-central collisions, K+ mesons preferentially are emitted perpendicular to the reaction plane. The strength of the azimuthal anisotropy of K+ emission is comparable to the one of pions. No in-plane flow was found for K+ mesons near projectile and target rapidity.Comment: Accepted for publication in Phys. Rev.Let

    New Ways of Synthesizing Potential Pterin Anti-Fungal Drugs

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    Pterin based compounds have shown some promise as potential anti-fungal compounds; however, the low solubility of them in most organic solvents make the synthesis of these compounds tedious and difficult. Work is underway to do some of the steps of the synthesis in a different order to avoid the solubility issues. The goal is to be able to synthesize the final furan intermediate before adding the very insoluble pterin group in the final step to bypass any solubility issues that were encountered in synthesizing this molecule. First, the chlorinated furan intermediate underwent a reaction with sodium azide to convert the chlorine group on the furan into an azide group. Currently, work is being done on the second step, a DBU amidation to convert an ester to an amide group with a BOC protected amine

    Ancient colonization of marginal habitats. A comparative analysis of case studies from the Ancient World

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    The present contribution deals with the concepts of marginal habitats in selected regions of the ancient world, ranging from modern Spain to the Jordanian desert and from Turkey to the Ethiopian highlands. Central to this research is the hypothesis that the occupation of areas beyond the ‘normal’ settlement patterns corresponds to colonization processes which reflect specific social strategies and may have stimulated the development of new technological skills. A review of ‘marginality’ research in various disciplines indicates that there is no comprehensive definition of the concept, which can be approached from a multitude of perspectives and with manifold objectives. A survey of the eight case studies and two more in-depth discussions of the sites of Musawwarat (Sudan) and Ayamonte (Spain) highlight the potentials as well as the limits of the archaeological investigation into past marginalities. Patterns of spatial marginalization are the easiest to detect. The studies also show that we must not limit our analysis to the adverse factors connected to different kinds of marginalities. Instead, our analyses suggest that spatially marginal areas were deliberately chosen for settlement – an integration with core-periphery approaches may help us to understand these scenarios, which have received little attention in ‘marginality’ research in archaeology or elsewhere so far

    Supercooled confined water and the Mode Coupling crossover temperature

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    We present a Molecular Dynamics study of the single particle dynamics of supercooled water confined in a silica pore. Two dynamical regimes are found: close to the hydrophilic substrate molecules are below the Mode Coupling crossover temperature, TCT_C, already at ambient temperature. The water closer to the center of the pore (free water) approaches upon supercooling TCT_C as predicted by Mode Coupling Theories. For free water the crossover temperature and crossover exponent γ\gamma are extracted from power-law fits to both the diffusion coefficient and the relaxation time of the late α\alpha region.Comment: To be published, Phys. Rev. Lett., 4 pages, 3 figures, revTeX, minor changes in the figures, references added, changes in the tex

    Medium Effects in Kaon and Antikaon Production in Nuclear Collisions at Subthreshold Beam Energies

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    Production cross sections of K+^+ and K^- mesons have been measured in C+C collisions at beam energies per nucleon below and near the nucleon-nucleon threshold. At a given beam energy, the spectral slopes of the K^- mesons are significantly steeper than the ones of the K+^+ mesons. The excitation functions for K+^+ and K^- mesons nearly coincide when correcting for the threshold energy. In contrast, the K+^+ yield exceeds the K^- yield by a factor of about 100 in proton-proton collisions at beam energies near the respective nucleon-nucleon thresholds.Comment: Accepted for publication in Phys. Rev. Let
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