Evidence from satellite altimetry for small-scale convection in the mantle

Small scale convection can be defined as that part of the mantle circulation in which upwellings and downwellings can occur beneath the lithosphere within the interiors of plates, in contrast to the large scale flow associated with plate motions where upwellings and downwellings occur at ridges and trenches. The two scales of convection will interact so that the form of the small scale convection will depend on how it arises within the large scale flow. Observations based on GEOS-3 and SEASAT altimetry suggest that small scale convection occurs in at least two different ways

Boulder Bands on Lobate Debris Aprons: Does Spatial Clustering Reveal Accumulation History for Martian Glaciations?

Glacial landforms such as lobate debris aprons (LDA) and Concentric Crater Fill (CCF) are the dominant debris-covered glacial landforms on Mars. These landforms represent a volumetrically significant component of the Amazonian water ice budget, however, because small craters (diameter D 0.5-1 km) are poorly retained glacial brain terrain surfaces, and, since the glacial landforms are geologically young, it is challenging to reliably constrain either individual glacial deposit ages or formational sequences in order to determine how quickly the glaciers accumulated. A fundamental question remaining is whether ice deposition and flow that formed LDA occurred episodically during a few, short instances, or whether glacial flow was quasi-continuous over a long period (~108 yr). Because glaciation is thought to be controlled largely by obliquity excursions, a larger question is whether glacial deposits on Mars exhibit regional to global characteristics that can be used to infer synchronicity of flow or degradation

Ultrathin Metallic Coatings Can Induce Quantum Levitation between Nanosurfaces

There is an attractive Casimir-Lifshitz force between two silica surfaces in a liquid (bromobenze or toluene). We demonstrate that adding an ultrathin (5-50{\AA}) metallic nanocoating to one of the surfaces results in repulsive Casimir-Lifshitz forces above a critical separation. The onset of such quantum levitation comes at decreasing separations as the film thickness decreases. Remarkably the effect of retardation can turn attraction into repulsion. From that we explain how an ultrathin metallic coating may prevent nanoelectromechanical systems from crashing together.Comment: 4 pages, 5 figure

Electron-hole imbalance in superconductor-normal metal mesoscopic structures

We analysed the electron-hole or, in another words, branch imbalance (BI) and the related electric potential $V_{imb}$ which may arise in a mesoscopic superconductor/normal metal (S/N) structure under non-equilibrium conditions in the presence of a supercurrent. Non-equilibrium conditions can be created in different ways: a) a quasiparticle current flowing between the N reservoirs; b) a temperature gradient between the N reservoirs and no quasiparticle current. It is shown that the voltage $V_{imb}$ oscillates with the phase difference $\phi$. In a cross-geometry structure the voltage $V_{imb}$ arises in the vertical branch and affects the conditions for a transition into the $\pi$-state.Comment: 6 pages, 5 figures, accepted for publication in Europhysics Letter

Functional and Biogenetical Heterogeneity of the Inner Membrane of Rat-Liver Mitochondria

Rat liver mitochondria were fragmented by a combined technique of swelling, shrinking, and sonication. Fragments of inner membrane were separated by density gradient centrifugation. They differed in several respects: electronmicroscopic appearance, phospholipid and cytochrome contents, electrophoretic behaviour of proteins and enzymatic activities. Three types of inner membrane fractions were isolated. The first type is characterized by a high activity of metal chelatase, low activities of succinate-cytochrome c reductase and of glycerolphosphate dehydrogenase, as well as by a high phospholipid content and low contents of cytochromes aa3 and b. The second type displays maximal activities of glycerolphosphate dehydrogenase and metal chelatase, but contains relatively little cytochromes and has low succinate-cytochrome c reductase activity. The third type exhibits highest succinate-cytochrome c reductase activity, a high metal chelatase activity and highest cytochrome contents. However, this fraction was low in both glycerolphosphate dehydrogenase activity and phospholipid content. This fraction was also richest in the following enzyme activities: cytochrome oxidase, oligomycin-sensitive ATPase, proline oxidase, 3-hydroxybutyrate dehydrogenase and rotenone-sensitive NADH-cytochrome c reductase. Amino acid incorporation in vitro and in vivo in the presence of cycloheximide occurs predominantly into inner membrane fractions from the second type. These data suggest that the inner membrane is composed of differently organized parts, and that polypeptides synthesized by mitochondrial ribosomes are integrated into specific parts of the inner membrane

Study of ATLAS sensitivity to FCNC top decays

The ATLAS experiment sensitivity to top quark Flavour Changing Neutral Current (FCNC) decays was studied at LHC using ttbar events. While one of the top quarks is expected to follow the dominant Standard Model decay t->bW, the other decays through a FCNC channel, i.e. t-> Z u(c), t-> gamma u(c) or t-> g u(c). Different types of analyses, applied to each FCNC decay mode, were compared. The FCNC branching ratio sensitivity (assuming a 5sigma signal significance) and 95% confidence level limits on the branching ratios (in the hypothesis of signal absence) were obtained

Encoded physics knowledge in checking codes for nuclear cross section libraries at Los Alamos

Checking procedures for processed nuclear data at Los Alamos are described. Both continuous energy and multi-group nuclear data are verified by locally developed checking codes which use basic physics knowledge and common-sense rules. A list of nuclear data problems which have been identified with help of these checking codes is also given

Nematic Ordering of Rigid Rods in a Gravitational Field

The isotropic-to-nematic transition in an athermal solution of long rigid rods subject to a gravitational (or centrifugal) field is theoretically considered in the Onsager approximation. The new feature emerging in the presence of gravity is a concentration gradient which coupled with the nematic ordering. For rodlike molecules this effect becomes noticeable at centrifugal acceleration g ~ 10^3--10^4 m/s^2, while for biological rodlike objects, such as tobacco mosaic virus, TMV, the effect is important even for normal gravitational acceleration conditions. Rods are concentrated near the bottom of the vessel which sometimes leads to gravity induced nematic ordering. The concentration range corresponding to phase separation increases with increasing g. In the region of phase separation the local rod concentration, as well as the order parameter, follow a step function with height.Comment: Full article http://prola.aps.org/abstract/PRE/v60/i3/p2973_

Influence of Supercurrents on Low-Temperature Thermopower in Mesoscopic N/S Structures

The thermopower of mesoscopic normal metal/superconductor structures has been measured at low temperatures. Effect of supercurrent present in normal part of the structure was studied in two cases: when it was created by applied external magnetic field and when it was applied directly using extra superconducting electrodes. Temperature and magnetic field dependencies of thermopower are compared to the numerical simulations based on the quasiclassical theory of the superconducting proximity effect.Comment: 21 pages, 12 figures. To be published in the proceedings of the ULTI conference organized in Lammi, Finland (2006