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An efficient electrocatalytic biosensor for sulfite detection was developed by co-immobilizing sulfite oxidase and cytochrome c with polyaniline sulfonic acid in a layer-by-layer assembly. QCM, UV-Vis spectroscopy and cyclic voltammetry revealed increasing loading of electrochemically active protein with the formation of multilayers. The sensor operates reagentless at low working potential. A catalytic oxidation current was detected in the presence of sulfite at the modified gold electrode, polarized at +0.1 V ( vs. Ag/AgCl 1 M KCl). The stability of the biosensor performance was characterized and optimized. A 17-bilayer electrode has a linear range between 1 and 60 mu M sulfite with a sensitivity of 2.19 mA M-1 sulfite and a response time of 2 min. The electrode retained a stable response for 3 days with a serial reproducibility of 3.8% and lost 20% of sensitivity after 5 days of operation. It is possible to store the sensor in a dry state for more than 2 months. The multilayer electrode was used for determination of sulfite in unspiked and spiked samples of red and white wine. The recovery and the specificity of the signals were evaluated for each sample.
We present varve chronologies for sediments from two maar lakes in the Valle de Santiago region (Central Mexico): Hoya La Alberca (AD 1852-1973) and Hoya Rincn de Parangueo (AD 1839-1943). These are the first varve chronologies for Mexican lakes. The varved sections were anchored with tephras from Colima (1913) and Paricutin (1943/1944) and (210)Pb ages. We compare the sequences using the thickness of seasonal laminae and element counts (Al, Si, S, Cl, K, Ti, Mn, Fe, and Sr) determined by micro X-ray fluorescence spectrometry. The formation of the varve sublaminae is attributed to the strongly seasonal climate regime. Limited rainfall and high evaporation rates in winter and spring induce precipitation of carbonates (high Ca, Sr) enriched in (13)C and (18)O, whereas rainfall in summer increases organic and clastic input (plagioclase, quartz) with high counts of lithogenic elements (K, Al, Ti, and Si). Eolian input of Ti occurs also in the dry season. Moving correlations (5-yr windows) of the Ca and Ti counts show similar development in both sequences until the 1930s. Positive correlations indicate mixing of allochthonous Ti and autochthonous Ca, while negative correlations indicate their separation in sublaminae. Negative excursions in the correlations correspond with historic and reconstructed droughts, El Nio events, and positive SST anomalies. Based on our data, droughts (3-7 year duration) were severe and centred around the following years: the early 1850s, 1865, 1880, 1895, 1905, 1915 and the late 1920s with continuation into the 1930s. The latter dry period brought both lake systems into a critical state making them susceptible to further drying. Groundwater overexploitation due to the expansion of irrigation agriculture in the region after 1940 induced the transition from calcite to aragonite precipitation in Alberca and halite infiltration in Rincn. The proxy data indicate a faster response to increased evaporation for Rincn, the lake with the larger maar dimensions, solar radiation receipt and higher conductivity, whereas the smaller, steeper Alberca maar responded rapidly to increased precipitation.
The satellite era brings new challenges in the development and the implementation of potential field models. Major aspects are, therefore, the exploitation of existing space- and ground-based gravity and magnetic data for the long-term. Moreover, a continuous and near real-time global monitoring of the Earth system, allows for a consistent integration and assimilation of these data into complex models of the Earth’s gravity and magnetic fields, which have to consider the constantly increasing amount of available data. In this paper we propose how to speed up the computation of the normal equation in potential filed modeling by using local multi-polar approximations of the modeling functions. The basic idea is to take advantage of the rather smooth behavior of the internal fields at the satellite altitude and to replace the full available gravity or magnetic data by a collection of local moments. We also investigate what are the optimal values for the free parameters of our method. Results from numerical experiments with spherical harmonic models based on both scalar gravity potential and magnetic vector data are presented and discussed. The new developed method clearly shows that very large datasets can be used in potential field modeling in a fast and more economic manner.
Special p-forms are forms which have components fµ1…µp equal to +1, -1 or 0 in some orthonormal basis. A p-form ϕ ∈ pRd is called democratic if the set of nonzero components {ϕμ1...μp} is symmetric under the transitive action of a subgroup of O(d,Z) on the indices {1, . . . , d}. Knowledge of these symmetry groups allows us to define mappings of special democratic p-forms in d dimensions to special democratic P-forms in D dimensions for successively higher P = p and D = d. In particular, we display a remarkable nested structure of special forms including a U(3)-invariant 2-form in six dimensions, a G2-invariant 3-form in seven dimensions, a Spin(7)-invariant 4-form in eight dimensions and a special democratic 6-form O in ten dimensions. The latter has the remarkable property that its contraction with one of five distinct bivectors, yields, in the orthogonal eight dimensions, the Spin(7)-invariant 4-form. We discuss various properties of this ten dimensional form.
Grouping patterns within the genus Tragelaphus suggest that species inhabiting open areas tend to live in larger groups, while species preferring dense habitats live solitarily or in small family groups. We asked if similar variation would be concealed in the within-species variation of bushbuck (Tragelaphus scriptus). Recent molecular phylogeographic analyses revealed several locally adapted forms of bushbuck in different ecoregions on the African continent. We compared group sizes of south-eastern bushbuck (Tragelaphus sylvaticus) among six different populations ("ecotypes"). To date, most data on the social organization of bushbuck have been collected from only one population in Queen Elizabeth National Park (QENP) in Uganda. This particular population, however, inhabits an unusual-comparatively open-habitat type, while bushbuck otherwise inhabit dense habitats, leaving doubt whether data collected in QENP are representative of the entire species. We, therefore, compared grouping patterns between ecotypes inhabiting rather open habitats (e.g., dianae and haywoodi) and ecotypes occupying rather dense habitats (e.g., massaicus and ornatus). In bachelor groups and in all-female (spinster) groups, single sightings were the most frequent "group type" in all populations examined. We detected no significant difference among ecotypes in relative frequencies of group size categories in the case of bachelor groups. Spinster group sizes were slightly (albeit significantly) smaller in QENP than in all other areas. Moreover, a comparison of two areas inside (low human pursuit) and outside Lake Mburo National Park (high hunting pressure) in Uganda revealed no significant difference in grouping patterns in response to human pursuit (as reported for impala [Aepyceros melampus] inhabiting the same area). Altogether, our results suggest that group sizes in bushbuck are not dependent on the habitat type they inhabit; neither does human nuisance have an impact on grouping patterns. Hence, an "almost solitary" lifestyle appears to be a characteristic of the entire taxon.
Why does Cecil Beaton choose Jackson Pollock paintings as backdrops for his fashion shoot for American Vogue in March of 1951? Beaton's photographs represent a special, highly ambivalent moment in the development of an American aesthetic identity in and through Vogue. His clearly "European gaze" instrumentalizes Pollock's paintings for his own purposes and highlights the long-lasting ideological conflict between European design and American identity. A close examination of the role of the magazine in shaping the self-image of America's upper classes, as well as of the function of these images within the parameters of the magazine itself and of abstract art within the series, offers an enriched understanding of the relationship of art and fashion in Vogue. These notorious images become the occasion for an analysis of the relationship between America's avant-garde and Vogue, the integration of their works into the structure of the magazine and their function therein. Situating the photographs within the socio- historical context of the magazine offers insight, as well, into Beaton's photos as a factor in an internal conflict at the magazine arising from the clash of Vogue's orientation on European and French fashion and lifestyle and its identity as a magazine for a specific, American upper-class audience. While Beaton's pictures incorporate the "strength" of American creativity, these images do not assert the equality of American with French design. The issue is no longer a fundamental legitimization of American design; much more, the newly reestablished dominance of the French as a creative force in fashion after the introduction of Dior's New Look had to be balanced with American reality. Beaton's images attempt to stage the newly reborn longing for a "feeling of Frenchness" and to integrate it with an essentially-American creativity in the New World through the use of Pollock's paintings.
In situ and ex situ SAXS investigation of colloidal sedimentation onto laterally patterned support
(2009)
We report on in situ investigations of colloidal ordering during gravity sedimentation from a colloidal suspension onto a prepatterned support using a polymeric surface relief grating (SRG) as the support. The ordering of colloids with a diameter of 420 nm was investigated by means of grazing-incidence small-angle X-ray scattering (GISAXS) and transmission SAXS using a preparation cell guaranteeing stable temperature and humidity. GISAXS was used for in situ monitoring of the time evolution of colloidal ordering within the whole illuminated sample area. The onset of ordering was indicated by the increase of integrated intensity within a small time frame shortly before complete evaporation of the dispersant. Single domains of coated samples were investigated ex situ by SAXS in transmission geometry where the irradiated sample area was 200 x 200 mu m(2) only. Domains with the typical size of a few millimeters were observed varying in orientation and crystallographic structure for various positions at the sample. They were mainly oriented along the grooves of the grating, confirming the influence of the underlying grating on colloidal ordering.
Three experiments investigated proactive interference and proactive facilitation in a memory-updating paradigm. Participants remembered several letters or spatial patterns, distinguished by their spatial positions, and updated them by new stimuli up to 20 times per trial. Self-paced updating times were shorter when an item previously remembered and then replaced reappeared in the same location than when it reappeared in a different location. This effect demonstrates residual memory for no-longer-relevant bindings of items to locations. The effect increased with the number of items to be remembered. With one exception, updating times did not increase, and recall of final values did not decrease, over successive updating steps, thus providing little evidence for proactive interference building up cumulatively.