Ubiquitin ligases and beyond

First paragraph (this article has no abstract): In a review published in 2004 [1] and that still repays reading today, Cecile Pickart traced the evolution of research on ubiquitination from its origins in the proteasomal degradation of proteins through the revelation that it has a central role in cell cycle regulation and the recognition of regulatory roles for ubiquitin in intracellular membrane transport, cell signalling, transcription, translation, and DNA repair

Marco Polo: A near Earth object sample return mission

From Introduction: MARCO POLO is a joint European-Japanese sample return mission to a Near-Earth Object. In late 2007 this mission was selected by ESA, in the framework of COSMIC VISION 2015-2025, for an assessment scheduled to last until mid 2009. This Euro-Asian mission will go to a primitive Near-Earth Object (NEO), such as a C or D type asteroid. The spacecraft will rendezvous with the object, and over an extended period scientifically characterize it at multiple scales and bring samples back to Earth for detailed scientific investigation

The song of the dunes as a self-synchronized instrument

Since Marco Polo (1) it has been known that some sand dunes have the peculiar ability of emitting a loud sound with a well defined frequency, sometimes for several minutes. The origin of this sustained sound has remained mysterious, partly because of its rarity in nature (2). It has been recognized that the sound is not due to the air flow around the dunes but to the motion of an avalanche (3), and not to an acoustic excitation of the grains but to their relative motion (4-7). By comparing several singing dunes and two controlled experiments, one in the laboratory and one in the field, we here demonstrate that the frequency of the sound is the frequency of the relative motion of the sand grains. The sound is produced because some moving grains synchronize their motions. The existence of a velocity threshold in both experiments further shows that this synchronization comes from an acoustic resonance within the flowing layer: if the layer is large enough it creates a resonance cavity in which grains self-synchronize.Comment: minor changes, essentially more references

Entropy calculation for a toy black hole

In this note we carry out the counting of states for a black hole in loop quantum gravity, however assuming an equidistant area spectrum. We find that this toy-model is exactly solvable, and we show that its behavior is very similar to that of the correct model. Thus this toy-model can be used as a nice and simplifying `laboratory' for questions about the full theory.Comment: 18 pages, 4 figures. v2: Corrected mistake in bibliography, added appendix with further result

Analytical methods in wineries: is it time to change?

A review of the methods for the most common parameters determined in wine—namely, ethanol, sulfur dioxide, reducing sugars, polyphenols, organic acids, total and volatile acidity, iron, soluble solids, pH, and color—reported in the last 10 years is presented here. The definition of the given parameter, official and usual methods in wineries appear at the beginning of each section, followed by the methods reported in the last decade divided into discontinuous and continuous methods, the latter also are grouped in nonchromatographic and chromatographic methods because of the typical characteristics of each subgroup. A critical comparison between continuous and discontinuous methods for the given parameter ends each section. Tables summarizing the features of the methods and a conclusions section may help users to select the most appropriate method and also to know the state-of-the-art of analytical methods in this area

In Vitro Antibacterial, Antioxidant and Anti-Inflammatory Effects of Senecio Asperulus and Gunnera Perpensa from Mohale’s Hoek, Lesotho

Original ArticleBackground: Traditional medicinal plants have been widely used to treat or manage various ailments for centuries in Lesotho. With an increase in multi drug resistance and undesired adverse events to current drugs challenges, there is a need for alternative drugs. Aim: In this study we aimed at the investigation of antibacterial, antioxidant and anti-inflammatory effects of Senecio asperulus and Gunnera perpensa roots extracted in three solvents of different polarities. Materials and Methods: Antibacterial activity was determined using the disc diffusion method, while antioxidant activity was determined using free radical scavenging of 2,2-diphenyl-1-picrylhydrazyl and the ferric reducing antioxidant power assay. The Lipopolysaccharide (LPS) stimulated RAW 264.7 mouse macrophage in vitro model was used to evaluate the anti-inflammatory activity of both plants. Resveratrol was used as a positive control. Results: Methanol extracts of Senecio asperulus inhibited microbial growth even at the lowest concentration of 50 μg/ml. Senecio asperulus dichloromethane extract was active on most bacteria with MIC’s between 50 μg/ml and 500 μg/ml. However, the water and methanol extracts of Gunnera perpensa had no activity against all organisms tested. Aqueous extracts of Senecio asperulus and Gunnera perpensa showed free radical scavenging activity yielding EC50 values of 100 μg/ml and 25 μg/ml, respectively. The aqueous extracts of Senecio asperulus showed moderate anti-inflammatory activity from 50 to 200 μg/ml. while the methanol extract was at 200 μg/ml and with no cytotoxicity. No anti-inflammatory activity was observed from all Gunnera perpensa extracts using LPS-induced macrophages, this suggests that this species may be using other mechanisms for anti-inflammatory activity. Conclusion: The antibacterial, antioxidant and anti-inflammatory activities observed from water extracts of Senecio asperulus support its ethnomedicinal use for the management of inflammation related diseases

Surface-plasmon-polariton wave propagation supported by anisotropic materials: multiple modes and mixed exponential and linear localization characteristics

The canonical boundary-value problem for surface-plasmon-polariton (SPP) waves guided by the planar interface of a dielectric material and a plasmonic material was solved for cases wherein either partnering material could be a uniaxial material with optic axis lying in the interface plane.Numerical studies revealed that two different SPP waves, with different phase speeds, propagation lengths, and penetration depths, can propagate in a given direction in the interface plane; in contrast, the planar interface of isotropic partnering materials supports only one SPP wave for each propagation direction. Also, for a unique propagation direction in each quadrant of the interface plane, it was demonstrated that a new type of SPP wave--called a surface-plasmon-polariton-Voigt (SPP-V) wave--can exist. The fields of these SPP-V waves decay as the product of a linear and an exponential function of the distance from the interface in the anisotropic partnering material; in contrast, the fields of conventional SPP waves decay only exponentially with distance from the interface. Explicit analytic solutions of the dispersion relation for SPP-V waves exist and help establish constraints on the constitutive-parameter regimes for the partnering materials that support SPP-V-wave propagation