Fragmentation effects on diversity of wasp community and its impact on fig/fig wasp interaction in Ficus racemosa L.

Habitat fragmentation usually results in alteration of species composition or biological communities. However, little is known about the effect of habitat fragmentation on the fig/fig wasp system. In this study, we compared the structure of a fig wasp community and the interaction between figs and fig wasps of Ficus racemosa L. in a primary forest, a locally fragmented forest and a highly fragmented forest. Our results show that, in the highly fragmented forest, the proportion of pollinator wasps is lower and the proportion of non-pollinator wasps is higher compared with the primary forest and locally fragmented forest. The proportion of fruits without pollinator wasps in mature fruits is also greatly increased in the highly fragmented forest. The proportion of galls in all female flowers increases in the highly fragmented forest, whereas the proportion of viable seeds does not change considerably. The disruption of groups of fig trees results in a decrease in pollinator wasps and even might result in the extinction of pollinator wasps in some extreme cases, which may transform the reciprocal interaction between figs and fig wasps into a parasite/host system. Such an effect may lead to the local extinction of this keystone plant resource of rain forests in the process of evolution, and thereby, may change the structure and function of the tropical rain forest.

Production cross sections of superheavy nuclei based on dinuclear system model

The barrier distribution function method is introduced in the dinuclear system model in the calculation of the transmission probability, which is the first stage in the synthesis of superheavy nuclei. Dynamical deformation and averaging collision orientations are considered in the calculation of the fusion probability by solving master equation numerically. Survival probability with respect to xn evaporation channel (x = 1-5) in the de-excitation process of the thermal compound nucleus is calculated, in which the level density of the Fermi-gas model is used. Production cross sections of a series of superheavy nuclei formed in the reactions taken magic and deformed nuclei as target in Ca-48 induced reactions are studied systematically. The calculated results are in good agreement with available experimental data. Isotopic dependence of the production cross sections in the reactions Ca-48 + Pu is analyzed.

System size dependence of associated yields in hadron-triggered jets STAR Collaboration

We present results on the system size dependence of high transverse momentum di-hadron correlations at root s(NN) = 200 GeV as measured by STAR at RHIC. Measurements in d + Au, Cu + Cu and Au + Au collisions reveal similar jet-like near-side correlation yields (correlations at small angular separation Delta phi similar to 0, Delta eta similar to 0) for all systems and centralities. Previous measurements have shown Chat the away-side (Delta phi similar to pi) yield is suppressed in heavy-ion collisions. We present measurements of the away-side Suppression as a function of transverse momentum and centrality in Cu + Cu and Au + Au collisions. The suppression is found to be similar in Cu + Cu and An + An collisions at a similar number of participants. The results are compared to theoretical calculations based on the patron quenching model and the modified fragmentation model. The observed differences between data and theory indicate that the correlated yields presented here will further constrain dynamic energy loss models and provide information about the dynamic density profile in heavy-ion collisions. (C) 2009 Elsevier B.V. All rights reserved.

Studies on the adduct reaction of disubstituted benzenes with ion system of acetone in gas phase

Ion - molecule reactions of disubstituted benzene with ion system of acetone and deuterium - labelled acetone under chemical ionization conditions were examined and the fragmentation reactions of the adduct ions formed by the ion - molecule reactions were studied using collision - induced dissociation (CID) technique. It was found that the electron - releasing groups favored the adduct reactions, whereas the electron - withdrawing groups did not. The position and properties of substituted groups affected the relative abundance of the adduct ions. The fragmentation reaction of the adduct ion formed by ortho - phenylenediamine with acetyl ion was similar to the reductive alkylation reaction of amine in condensed phase.

H/D exchange reaction of cyclopropane derivatives in the ion system of CD3OD

The fragmentation properties of the product ions [M + 1](+), [M + 2](+) and [M + 3](+) formed by ion-molecule reaction of four cyclopropane derivatives with the ion system of CD3OD were investigated by using collision-induced dissocation technique. The experiment results indicated that the product ions were produced via the H/D exchange reaction between reactants and reactive reagent ions of CD3OD. There are two exchangable hydrogen atoms on the ring of compounds 1 and 2, and only one for compound 3 and 4.