Vertical extension of the subglacial drainage system into basal crevasses

Water plays a first-order role in basal sliding of glaciers and ice sheets and is often a key constituent of accelerated glacier motion. Subglacial water is known to occupy systems of cavities and conduits at the interface between ice and the underlying bed surface, depending upon the history of water input and the characteristics of the substrate. Full understanding of the extent and configuration of basal water is lacking, however, because direct observation is difficult. This limits our ability to simulate ice dynamics and the subsequent impacts on sea-level rise realistically. Here we show that the subglacial hydrological system can have a large volume of water occupying basal crevasses that extend upward from the bed into the overlying ice. Radar and seismic imaging combined with in situ borehole measurements collected on Bench Glacier, Alaska, reveal numerous water-filled basal crevasses with highly transmissive connections to the bed. Some crevasses extend many tens of metres above the bed and together they hold a volume of water equivalent to at least a decimetre layer covering the bed. Our results demonstrate that the basal hydrologic system can extend high into the overlying ice mass, where basal crevasses increase water-storage capacity and could potentially modulate basal water pressure. Because basal crevasses can form under commonly observed glaciological conditions, our findings have implications for interpreting and modelling subglacial hydrologic processes and related sliding accelerations of glaciers and ice sheets.     

Orientation to learning context modulates retrieval processing for unrecognized words

Explicit memory errors may occur when individuals fail to retrieve information about items previously studied (item memory) or about the learning context (source memory). We examined electrophysiological measures during recognition failure in order to determine the influence of retrieval orientation for item versus source information. Recognition failure was associated with brain potentials distinct from those associated with success. Furthermore, source-memory failures were associated with earlier-onset brain potentials with a more anterior distribution compared to item-memory failures. Neurocognitive processing was thus modulated by retrieval orientation so as to differentially influence neural correlates of successful versus unsuccessful retrieval.     

Uncontrolled C3 activation causes membranoproliferative glomerulonephritis in mice deficient in complement factor H

The alternative pathway of complement is activated continuously in vivo through the C3 'tick-over' pathway. This pathway is triggered by the hydrolysis of C3, resulting in the formation of C3 convertase. This, in turn, generates C3b, which mediates many of the biological functions of complement. Factor H, the main regulator of this activation, prevents formation and promotes dissociation of the C3 convertase enzyme, and, together with factor I, mediates the proteolytic inactivation of C3b. Factor H deficiency, described in 29 individuals from 12 families and in pigs, allows unhindered activation of fluid-phase C3 and severe depletion of plasma C3 (ref. 11). Membranoproliferative glomerulonephritis (MPGN) occurs in factor H-deficient humans and pigs. Although MPGN has been reported in other conditions in which uncontrolled activation of C3 occurs, the role of C3 dysregulation in the pathogenesis of MPGN is not understood. Here we show that mice deficient in factor H (Cfh(-/-) mice) develop MPGN spontaneously and are hypersensitive to developing renal injury caused by immune complexes. Introducing a second mutation in the gene encoding complement factor B, which prevents C3 turnover in vivo, obviates the phenotype of Cfh(-/-) mice. Thus, uncontrolled C3 activation in vivo is essential for the development of MPGN associated with deficiency of factor H.     

The binary Kuiper-belt object 1998 WW31

The recent discovery of a binary asteroid during a spacecraft fly-by generated keen interest, because the orbital parameters of binaries can provide measures of the masses, and mutual eclipses could allow us to determine individual sizes and bulk densities. Several binary near-Earth, main-belt and Trojan asteroids have subsequently been discovered. The Kuiper belt-the region of space extending from Neptune (at 30 astronomical units) to well over 100 AU and believed to be the source of new short-period comets-has become a fascinating new window onto the formation of our Solar System since the first member object, not counting Pluto, was discovered in 1992 (ref. 13). Here we report that the Kuiper-belt object 1998 WW31 is binary with a highly eccentric orbit (eccentricity e approximately 0.8) and a long period (about 570 days), very different from the Pluto/Charon system, which was hitherto the only previously known binary in the Kuiper belt. Assuming a density in the range of 1 to 2 g cm-3, the albedo of the binary components is between 0.05 and 0.08, close to the value of 0.04 generally assumed for Kuiper-belt objects.     

Complex formation between glycerol and metal ions as studied by means of ESR,NMR, and optical absorption spectroacopy

Zusammenfassung Es wurden die ESR-, NMR- und die optischen Absorptionsspektren für Fe³⁺, Cu²⁺ und Mn²⁺ in Wasser- oder Glycerollösungen bestimmt. Die untersuchten Metallionen bilden einen Komplex mit Glycerol.     

Fisheries: mislabelling of a depleted reef fish

Any fish species that appears to be readily available in the marketplace will create an impression among the public that there is a plentiful supply of that fish in the sea, but this may belie the true state of the fisheries' stock. Here we use molecular genetic analysis to show that some three-quarters of the fish sold in the United States as 'red snapper'--the US Food and Drug Administration's legally designated common name for Lutjanus campechanus--belong to another species. Mislabelling to this extent not only defrauds consumers but could also adversely affect estimates of stock size if it influences the reporting of catch data that are used in fisheries management.