Heavy Quarkonia Spectroscopy and Decays

The experimental status of stable bound states made out of heavy quarks is reviewed. The need for a way to deal with the non-perturbative transitions involved calls for precision measurements on one hand, and for discovery of as yet undetected states to confirm predictions on the other. In this article, recent experimental contributions to heavy quarkonia spectroscopy and decay will be reviewed, mostly from data analyzed by the BES and CLEO collaborations. The most dramatic recent discoveries include the detection of the first stable L=2 state, and a first non-pionic hadronic transition in the Upsilon system, and a first measurement of chi_cJ --> Lambda Lambdabar. Scans of the psi' and Upsilon(1,2,3S) resonances are used to add information on partial and total decay widths.Comment: Invited talk at the XXIII Physics in Collisions Conference (PIC03), Zeuthen, Germany, June 2003, 14 pages, LaTeX, 9 figures. PSN SAAT0

Visual aesthetics and the user experience

User experience is conceptualized as a phenomenon consisting of instrumental and non-instrumental quality perceptions as well as emotional user reactions. Visual aesthetics is defined as one non-instrumental quality and available methods are applied to measure the perception of visual aesthetics of interactive systems. Selected results of two studies are reported that addressed the influence of perceived usability and visual aesthetics on emotional user reactions and consequences of user experience and studied the effect of user characteristics and contextual parameters on these relations. The results show that usability and visual aesthetics can be perceived independently. Furthermore, the relevance of perceived visual aesthetics for emotional user reactions and consequences of user experience is demonstrated. However, the results reveal that the importance depends on user characteristics, e.g. the centrality of visual product aesthetics, and context parameters, e.g. the goaldirectedness of the interaction

Geochemistry of volcanic rocks from the Woodlark Basin

EGU2011-12864 The Woodlark Basin east of Papua New Guinea represents one of the few places on Earth where a spreading axis propagates into continental crust. This special tectonic setting allows insights into the evolution of magma composition as continental extension and break-up changes to the formation of ocean crust. We report here geochemical results on samples collected in 2009 from the four segments closest to the continental breakup, from segment 1 which abuts the detachment fault responsible for continental extension on Moresby Seamount in the West, to segment 4, representing mature oceanic crust in the East. A total of 208 glass samples have been analyzed for their major (EMPA) and trace element (LA-ICPMS) compositions. The data show strong E-W variations. Samples ranging from tholeiitic basalt and basaltic andesite to andesite and rhyolite are found on Segment 1. They have generally high alkali values and a wide range of trace element contents and ratios. Segments 2 to 4 magmas in contrast only comprise tholeiitic basalt with lower alkali contents and a more restricted range of trace element chemistry. The geochemical differences between the segments cannot be attributed to differentiation processes alone, and different sources are required. High Ba/La, (La/Sm)N, Rb/Sr, and Th/La on Segment 1 suggest a derivation from an enriched mantle source, while low Nd/Pb and Nb/U suggest that some of the enrichment may also reflect the influence of continental crust during magma genesis. Whether this continental signature is present in the form of recycled material in the mantle or as rafted continental blocks in the axial region is at present unclear. In contrast to rocks from segment 1, trace element compositions of volcanic glasses from segments 2 to 4 show a stronger MORB signature, presumably reflecting more mature spreading in this part of the basin. The influence of continental material appears to be minimal, suggesting that uncontaminated asthenosphere quickly flows into the rift and/or that continental blocks are not retained in the axial region for long time periods following the rifting-spreading transition

Sorting pathways of mitochondrial inner membrane proteins

Two distinct pathways of sorting and assembly of nuclear-encoded mitochondrial inner membrane proteins are described. In the first pathway, precursor proteins that carry amino-terminal targeting signals are initially translocated via contact sites between both mitochondrial membranes into the mitochondrial matrix. They become proteolytically processed, interact with the 60-kDa heat-shock protein hsp60 in the matrix and are retranslocated to the inner membrane. The sorting of subunit 9 of Neurospora crassa Fo-ATPase has been studied as an example. Fo subunit 9 belongs to that class of nuclear-encoded mitochondrial proteins which are evolutionarily derived from a prokaryotic ancestor according to the endosymbiont hypothesis. We suggest that after import into mitochondria, these proteins follow the ancestral sorting and assembly pathways established in prokäryotes (conservative sorting). On the other hand, ADP/ATP carrier was found not to require interaction with hsp60 for import and assembly. This agrees with previous findings that the ADP/ATP carrier possesses non-amino-terminal targeting signals and uses a different import receptor to other mitochondrial precursor proteins. It is proposed that the ADP/ATP carrier represents a class of mitochondrial inner membrane proteins which do not have a prokaryotic equivalent and thus appear to follow a non-conservative sorting pathway

On the fluid-mobility of molybdenum, tungsten, and antimony in subduction systems

Molybdenum (Mo) and tungsten (W) have long been regarded as being more or less immobile during slab fluid-induced arc magma generation. Here we characterize about 180 samples of young, predominantly mafic to intermediate tephras and lavas for their Mo, W, and antimony (Sb) concentrations, to examine the fluid-mobility of these elements in subduction systems. Samples were taken along the active arcs of the Chilean Southern Volcanic Zone (SVZ) and the Central American Volcanic Arc (CAVA). When relating Mo, W, and Sb to trace element ratios typically used to constrain the involvement of subduction fluids in magma formation, such as Ba/La or U/Th, Mo, W, and Sb are enriched in the most fluid-influenced, highest-degree melts. W/Mo ratios correlate positively with Pb/Ce, which is established to reflect a recent subduction signal or assimilation of crustal material with an ancient subduction signature, suggesting that subduction processes promote enrichment of W over Mo. This is well expressed at the SVZ and most of the CAVA; while few OIB-type rocks from Central Costa Rica form an opposite trend. Moreover, Mo/W ratios co-vary with Cl contents derived from melt inclusions, indicating that the relative degree of mobilization responds to the composition of the subduction fluid. To evaluate the mobility of Mo, W, and Sb during metamorphism in the slab, eclogites with no or minor metasomatic overprint and a fluid-induced overprint in an eclogite-blueschist sequence were investigated. None of the three elements shows a systematic variability related to metasomatism and the minor variations are interpreted to reflect protolith heterogeneity. This suggests that Mo, W and Sb remain relatively immobile up to depths of 70 km in the subduction zone

Asteroid Taxonomy from Cluster Analysis of Spectrometry and Albedo

The classification of the minor bodies of the Solar System based on observables has been continuously developed and iterated over the past 40 years. While prior iterations followed either the availability of large observational campaigns or new instrumental capabilities opening new observational dimensions, we see the opportunity to improve primarily upon the established methodology. We developed an iteration of the asteroid taxonomy which allows the classification of partial and complete observations (i.e. visible, near-infrared, and visible-near-infrared spectrometry) and which reintroduces the visual albedo into the classification observables. The resulting class assignments are given probabilistically, enabling the uncertainty of a classification to be quantified. We built the taxonomy based on 2983 observations of 2125 individual asteroids, representing an almost tenfold increase of sample size compared with the previous taxonomy. The asteroid classes are identified in a lower-dimensional representation of the observations using a mixture of common factor analysers model. We identify 17 classes split into the three complexes C, M, and S, including the new Z-class for extremely-red objects in the main belt. The visual albedo information resolves the spectral degeneracy of the X-complex and establishes the P-class as part of the C-complex. We present a classification tool which computes probabilistic class assignments within this taxonomic scheme from asteroid observations. The taxonomic classifications of 6038 observations of 4526 individual asteroids are published. The ability to classify partial observations and the reintroduction of the visual albedo provide a taxonomy which is well suited for the current and future datasets of asteroid observations, in particular provided by the Gaia, MITHNEOS, NEO Surveyor, and SPHEREx surveys.Comment: Published in Astronomy and Astrophysics. The table of asteroid classifications and the templates of the defined taxonomic classes are available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/665/A2