Novel features of diffraction at the LHC

Interest and problems in the studies of diffraction at LHC are highlighted. Predictions for the global characteristics of proton-proton interactions at the LHC energy are given. Potential discoveries of the antishadow scattering mode and diffractive scattering conjugated with high--$E_T$ jets are discussed.Comment: 10 pages, 7 figures, journal version, 1 figure added, extended introductio

Using binary statistics in Taurus-Auriga to distinguish between brown dwarf formation processes

Whether BDs form as stars through gravitational collapse ("star-like") or BDs and some very low-mass stars constitute a separate population which form alongside stars comparable to the population of planets, e.g. through circumstellar disk ("peripheral") fragmentation, is one of the key questions of the star-formation problem. For young stars in Taurus-Auriga the binary fraction is large with little dependence on primary mass above ~0.2Msun, while for BDs it is <10%. We investigate a case in which BDs in Taurus formed dominantly through peripheral fragmentation. The decline of the binary frequency in the transition region between star-like and peripheral formation is modelled. A dynamical population synthesis model is employed in which stellar binary formation is universal. Peripheral objects form separately in circumstellar disks with a distinctive initial mass function (IMF), own orbital parameter distributions for binaries and a low binary fraction. A small amount of dynamical processing of the stellar component is accounted for as appropriate for the low-density Taurus-Auriga embedded clusters. The binary fraction declines strongly between the mass-limits for star-like and peripheral formation. The location of characteristic features and the steepness depend on these mass-limits. Such a trend might be unique to low density regions hosting dynamically unprocessed binary populations. The existence of a strong decline in the binary fraction -- primary mass diagram will become verifiable in future surveys on BD and VLMS binarity in the Taurus-Auriga star forming region. It is a test of the (non-)continuity of star formation along the mass-scale, the separateness of the stellar and BD populations and the dominant formation channel for BDs and BD binaries in regions of low stellar density hosting dynamically unprocessed populations.Comment: accepted for publication in A&A, 11 pages, 4 figures, 1 tabl

Comparison of the post-fire dynamics of the ectomycorrhizal community in two Quercus ilex stands in Northern Spain

A comparative study of the post-fire recolonization of ectomycorrhizae in two evergreen oak stands (Quercus ilex L. subsp. ballota (Desf.) Samp.) in Nazar and San Cristóbal (Navarra, Spain) has been carried out. In 1993 a stand in Nazar burnt, but it was not until 1998 that the study started. On the contrary, the study in San Cristóbal started immediately after the stand had caught fire in 2000. Therefore we have been able to compare the regeneration in both stands and the species composition five years after the fire and immediately after the fire, as well as the differences in ectomycorrhizal colonization and abundance of morphotypes between the burnt plots and areas which remained undisturbed in both forests, thus acting as control plots. In both sites the percentage of ectomycorrhizal colonization tended to be lower after the wildfire. In San Cristóbal, in the burnt site there was a lower abundance of morphotypes compared to the control site. However, in Nazar, five years after the fire, we did not find any significant change in species richness, but rather a shift in the abundance of each morphotype when comparing the burnt and the control plots. There are some species of mycorrhizal fungi which seem to be particularly adapted to fire, such as Type 1 in San Cristóbal and Cenococcum geophilum in Nazar. Sphaerosporella brunnea, a pioneer species considered to be especially suitable for the colonization of burnt substrates, was only found in Nazar

A revision of the descriptions of ectomycorrhizas published since 1961

All available publications providing descriptions of ectomycorrhizas (ECM) were reviewed in order to build a database containing details on fungus forming the ECM, host tree, country where the material for description was collected, and habitat of the ECM. Other secondary data were also recorded. In all 1244 descriptions of ECM published since 1961 in 479 papers were reviewed. The number of different ECM morphotypes described was 814. Most ECM described were collected in Europe and North America. Gymnosperms were the most common tree associates, and boreal and temperate forests the most studied ecosystems. Fungal symbionts were mostly Basidiomycota, epigeous, and with mushroom-like morphology. The paper also addresses the gaps in ECM knowledge that mycorrhizologists should address in future studies