Real time visualization of Quantum Molecular Dynamics

this demonstration displays results of a Quantum Molecular Dynamics (QMD) simulation of the metal cluster Li{sub 6} running on the Intel Touchstone Delta at Caltech

Shell occupation by the endemic western Atlantic hermit crab Isocheles sawayai (Diogenidae) from Caraguatatuba, Brazil

The aim of this study was to characterize the pattern of shell occupation by the hermit crab Isocheles sawayai Forest and Saint-Laurent, 1968, from the Caraguatatuba region. The percentage of shell types that were occupied and the morphometric relationships between hermit crabs and occupied shells were analyzed from systematized collections that were conducted monthly from July 2001 to June 2003. A total of 373 individuals were captured (297 males, 41 non-ovigerous females, 25 ovigerous females and 10 intersexes), occupying 17 species of gastropod shells. Stramonita haemastoma (Linnaeus, 1767) (49.87%) was the significantly most occupied species (&#967;2 = 89.30; P < 0.05) followed, with no significant difference, by Phalium granulatum (Born, 1778) (11.53%), Polinices hepaticus (Roding, 1798) (8.31%) and Cymatium parthenopeum (von Salis, 1793) (6.97%). All the morphometric relationships between hermit crabs and occupied shells showed high (r > 0.68) and significant (P < 0.05) correlation values, which is an important indication that in this I. sawayai population the animals occupied adequate shells. The high number of occupied shell species and relative plasticity indicated that, for the studied population, occupation is influenced by the shell availability

Dendrogeomorphology in landslide analysis. State of art

Consiglio Nazionale delle Ricerche (CNR). Biblioteca Centrale / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Survival Response of Larix Sibirica to the Tunguska Explosion

The disastrous Tunguska explosion (TE) in 1908 uprooted trees in a radial pattern. Several trees in this area survived and kept growing in the post-Tunguska environment. We collected samples from surviving trees (14 and 131 years old at the time of the TE) that lived until collection in 2008 and another sample from a control tree farther from the blast epicenter (germination in 1928), which were analyzed by X-ray fluorescence (XRF) and prompt gamma neutron activation analysis. Chemical composition of xylem tracheids of the surviving trees revealed several patterns potentially related to the TE. A calcium peak is associated with the 1908 ring in both of the exposed trees, but additional high concentrations in adjacent rings could represent enhanced translocation of Ca over the whole sapwood as a response to defoliation from the TE. Sr and Mn anomalies near 1908 appeared in one exposed tree but not in the other. High-resolution XRF indicates Ca as well as Zn anomalies are primarily located in the earlywood of the rings, whereas peaks in Mn, Zn and Cu are more associated with the latewood. A directional response was evidenced by a wider zone of elevated Ca in the rings on the southern side toward the airblast, which might have experienced the greatest defoliation and perhaps enhanced root damage as the tree was rocked by the pressure wave. The TE event in the middle of the 1908 growing season must have triggered tree responses to deliver more nutritive resources to the crown in order to hasten restoring new leaves in the crown and to aid in structural repair. © 2017 by The Tree-Ring Society.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]

An ab initio MO-LCAO investigation of the electronic structure of organic hydroperoxides and platinum(II) hydroperoxo complexes: a contribution to the knowledge of the mechanism of olefin epoxidation

A possible new process of activation of the OOH group in the mechanism of ethylene epoxidation catalysed by Pt(II) diphosphine complexes has been investigated by ab initio MO-LCAO calculations. The electronic and geometric features of YOOH species (Y = H, CH3, t-But, CF3, CH3CO, (PH3)2Pt(CF3), (PH3)2PtCl) have been evaluated and compared. Coordination of the OOH group to platinum induces an inversion of the polarity of the O-O bond when compared to any organic hydroperoxide; parallelly it favours the isomerisation of the OOH group from a hydroperoxo to an oxywater-like structure. This latter effect could be an important factor in favouring the reaction of the platinum coordinated OOH group with ethylene to form ethylene oxide. In fact, calculations on the energetics of the interaction between H2O2 and C2H4 have shown that isomerisation of HOOH to H2OO oxywater structure is the rate determining step for the epoxidation process