Beach face dynamics as affected by ground water table elevations

This report presents the results of laboratory studies which were carried out in the Coastal and Oceanographical Engineering Laboratory to investigate the effects of ground water table elevations on the beach profile changes over the swash zone. The experiment was conducted at three different water table levels while the other experimental conditions were fixed to constant values with regular waves. The water table levels included (1) normal water table level which is the same as mean sea level, (2) a higher level and (3) a lower level than the mean sea level. Special attention was given to the higher water level to investigate whether this level enhances erosion of the beach face and also to methods of interpreting the experimental data. The experiment described herein was carried out with a fairly fine sand and has demonstrated the significance of beach water table on profile dynamics. The increased water table level caused distinct effects in three definite zones. First, erosion occurred at the base of the beach face and the sand eroded was carried up and deposited on the upper portion of the beach face. Secondly, the bar trough deepened considerably and rapidly and the eroded sand was deposited immediately landward. This depositional area changed from mildly erosional to strongly depositional. Third, the area seaward of the bar eroded with a substantial deepening. The lowered water table appeared to result in a much more stable beach and the resulting effects were much less. The only noticeable trend was a limited deposition in the scour area at the base of the beach face. (Document has 37 pages.

Lovelock black holes surrounded by quintessence

Lovelock gravity consisting of the dimensionally continued Euler densities is a natural generalization of general relativity to higher dimensions such that equations of motion are still second order, and the theory is free of ghosts. A scalar field with a positive potential that yields an accelerating universe has been termed quintessence. We present exact black hole solutions in $D$-dimensional Lovelock gravity surrounded by quintessence matter and also perform a detailed thermodynamical study. Further, we find that the mass, entropy, and temperature of the black hole are corrected due to the quintessence background. In particular, we find that phase transition occurs with divergence of heat capacity at the critical horizon radius, and that specific heat becomes positive for $r_h<r_c$ allowing the black hole to become thermodynamically stable.Comment: 15 pages, 3 figures, accepted for publication in EPJ

3D mapping of the SPRY2 domain of ryanodine receptor 1 by single-particle Cryo-EM

The type 1 skeletal muscle ryanodine receptor (RyR1) is principally responsible for Ca(2+) release from the sarcoplasmic reticulum and for the subsequent muscle contraction. The RyR1 contains three SPRY domains. SPRY domains are generally known to mediate protein-protein interactions, however the location of the three SPRY domains in the 3D structure of the RyR1 is not known. Combining immunolabeling and single-particle cryo-electron microscopy we have mapped the SPRY2 domain (S1085-V1208) in the 3D structure of RyR1 using three different antibodies against the SPRY2 domain. Two obstacles for the image processing procedure; limited amount of data and signal dilution introduced by the multiple orientations of the antibody bound in the tetrameric RyR1, were overcome by modifying the 3D reconstruction scheme. This approach enabled us to ascertain that the three antibodies bind to the same region, to obtain a 3D reconstruction of RyR1 with the antibody bound, and to map SPRY2 to the periphery of the cytoplasmic domain of RyR1. We report here the first 3D localization of a SPRY2 domain in any known RyR isoform.The authors want to thank the Brigham and Women’s Hospital Biomedical Research Institute (to MS), the Australian National Health and the Medical Research Council (471418 to AD, MC and PB), and the European Commission (Marie Curie Action PIOF-GA-2009-237120 to AP-M)

A Homogeneous Sample of Sub-DLAs IV: Global Metallicity Evolution

An accurate method to measure the abundance of high-redshift galaxies consists in the observation of absorbers along the line of sight toward a background quasar. Here, we present abundance measurements of 13 z>3 sub-Damped Lyman-alpha Systems (quasar absorbers with HI column density 19 < log N(HI) < 20.3 cm^-2) based on the high resolution observations with VLT UVES spectrograph. These observations more than double the metallicity information for sub-DLAs previously available at z>3. This new data, combined with other sub-DLA measurements from the literature, confirm the stronger metallicity redshift evolution than for the classical Damped Lyman-alpha absorbers. Besides, these observations are used to compute for the first time the fraction of gas ionised from photo-ionisation modelling in a sample of sub-DLAs. Based on these results, we calculate that sub-DLAs contribute no more than 6% of the expected amount of metals at z~2.5. We therefore conclude that even if sub-DLAs are found to be more metal-rich than classical DLAs, they are insufficient to close the so-called ``missing metals problem''.Comment: 30 figures, 24 tables. Accepted for publication in MNRA