Spatial organization of a shredder guild of caddisflies (Trichoptera) in a riffle – Searching for the effect of competition

The shredder guild plays an outstanding role in the functioning of headwater stream ecosystems by processing allochthonous leaf litter. Traditionally, the abiotic habitat template is regarded as the major determinant of its organization, and only a limited number of studies support the importance of biotic interactions. The aim of the present study was to examine whether competition plays a significant role in organizing the shredder guild of caddisflies in a riffle. Null-model based co-occurrence, co-existence and guild variation analyses were used in the study of guild organization. In addition, the traditional variance to mean ratio was applied for measuring the intraspeclific aggregation of guild members. The non-significant metric values of co-occurrence and co-existence analyses predicted that competition was of limited importance in structuring the spatial organization of the shredder guild. The observed aggregated spatial distribution of species, suggests that besides stochastic events, deterministic forces should also contribute to the organization of the shredder guild of caddistlies

Transverse momentum and pseudorapidity distributions of charged hadrons in pp collisions at (s)\sqrt(s) = 0.9 and 2.36 TeV

Measurements of inclusive charged-hadron transverse-momentum and pseudorapidity distributions are presented for proton-proton collisions at sqrt(s) = 0.9 and 2.36 TeV. The data were collected with the CMS detector during the LHC commissioning in December 2009. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be 0.46 +/- 0.01 (stat.) +/- 0.01 (syst.) GeV/c at 0.9 TeV and 0.50 +/- 0.01 (stat.) +/- 0.01 (syst.) GeV/c at 2.36 TeV, for pseudorapidities between -2.4 and +2.4. At these energies, the measured pseudorapidity densities in the central region, dN(charged)/d(eta) for |eta| < 0.5, are 3.48 +/- 0.02 (stat.) +/- 0.13 (syst.) and 4.47 +/- 0.04 (stat.) +/- 0.16 (syst.), respectively. The results at 0.9 TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in p-pbar and pp collisions. The results at 2.36 TeV represent the highest-energy measurements at a particle collider to date