[1] Mapping and sampling of 18 eruptive units in two study areas along the Galápagos Spreading Center (GSC) provide insight into how magma supply affects mid-ocean ridge (MOR) volcanic eruptions. The two study areas have similar spreading rates (53 versus 55 mm/yr), but differ by 30% in the time-averaged rate of magma supply (0.3 Â 10 6 versus 0.4 Â 10 6 m 3 /yr/km). Detailed geologic maps of each study area incorporate observations of flow contacts and sediment thickness, in addition to sample petrology, geomagnetic paleointensity, and inferences from high-resolution bathymetry data. At the lower-magma-supply study area, eruptions typically produce irregularly shaped clusters of pillow mounds with total eruptive volumes ranging from 0.09 to 1.3 km 3 . At the higher-magma-supply study area, lava morphologies characteristic of higher effusion rates are more common, eruptions typically occur along elongated fissures, and eruptive volumes are an order of magnitude smaller (0.002-0.13 km 3 ). At this site, glass MgO contents (2.7-8.4 wt. %) and corresponding liquidus temperatures are lower on average, and more variable, than those at the lower-magma-supply study area (6.2-9.1 wt. % MgO). The differences in eruptive volume, lava temperature, morphology, and inferred eruption rates observed between the two areas along the GSC are similar to those that have previously been related to variable spreading rates on the global MOR system. Importantly, the documentation of multiple sequences of eruptions at each study area, representing hundreds to thousands of years, provides constraints on the variability in eruptive style at a given magma supply and spreading rate.

Aims In the USA, transthyretin cardiac amyloidosis usually results from ‘wild-type’ transthyretin (senile cardiac amyloidosis [SCA]) or the V122I variant. Patients & methods We compared presentations and outcomes among SCA and V122I patients referred to the Center for Advanced Cardiac Care at Columbia University Medical Center (NY, USA) between 2001 and 2012. Results V122I patients were younger (mean: 71 years, standard deviation [SD]: 7) than SCA patients (mean: 77, SD: 6; p = 0.0002) and 96% were black compared with 3% of SCA patients (p < 0.0001). Average ejection fraction was lower among V122I patients (mean: 25% [SD: 12] vs mean: 47% [SD: 15]; p = 0.0001), as was mean cardiac index. Median time to death or orthotopic heart transplant was 36.4 months for V122I patients and 66.5 for SCA patients (p = 0.09). Conclusion In this study of patients with transthyretin cardiac amyloidosis, V122I patients presented to a tertiary academic medical center at a younger age than SCA patients but had higher levels of cardiac dysfunction, despite genetic screening availability. There was a trend toward shorter time to orthotopic heart transplant or death among V122I patients. Whether this is a result of a different biologic progression or late diagnosis requires further study.

The Earth's mantle is isotopically heterogeneous on length scales ranging from centimetres to more than 10 4 kilometres 1,2 . This heterogeneity originates from partial melt extraction and plate tectonic recycling, whereas stirring during mantle convection tends to reduce it. Here we show that mid-ocean ridge basalts from 2,000 km along the southeast Indian ridge (SEIR) display a bimodal hafnium isotopic distribution. This bimodality reveals the presence of ancient compositional striations (streaks) in the Indian Ocean upper mantle. The number density of the streaks is described by a Poisson distribution, with an average thickness of ,40 km. Such a distribution is anticipated for a well-stirred upper mantle, in which heterogeneity is continually introduced by plate tectonic recycling, and redistributed by viscous stretching and convective refolding.The SEIR stretches from the Rodrigues Triple Junction (25.68 S, 70.18 E) to the Macquarie Triple Junction (628 S, 1518 E). Between 768-788 E it crosses the Amsterdam-St Paul (ASP) plateau, a pronounced bathymetric swell associated with relatively hot mantle upwelling beneath the Amsterdam and St Paul islands, while between 1208 E and 1288 E it crosses the Australian-Antarctic discordance (AAD), a region of deep bathymetry (.4,000 m) associated with relatively cold mantle and low melt production 3 . Notably, over a distance of ,2,500 km, between 868 E and 1208 E, there is a regular eastward decrease in axial depth from 2,300 to 5,000 m, and a morphological transition from axial high to axial valley due to decreasing melt production rate and crustal thickness. This depth gradient occurs at an intermediate and uniform spreading rate (70-75 mm yr 21 full rate) and in the absence of large transform offsets and nearby mantle hotspots. The range in axial depth and ridge morphology is similar to the global range for spreading ridges away from hotspots, making the SEIR a regional-scale analogue of the 50,000-km-long global ocean ridge system. Previous work has established that the He, Pb, Sr and Nd isotope variations along the SEIR are primarily controlled by variation in the depth of melting of isotopically heterogeneous mantle [4][5][6][7] . Also, all SEIR lavas west of the AAD are true 'Indian-type' on the basis of their elevated 208 Pb/ 206 Pb ratios 6 . New Hf isotope results have been obtained for 48 SEIR basalts previously analysed for He-Ne-Ar and Pb-Nd-Sr isotope compositions 4-7 (see Supplementary Table 1). All samples are fresh midocean ridge basalt (MORB) glasses that were microscopically handpicked to be free of surface alteration. Between 300 and 600 mg of this glass was digested and the Hf separated using ultrapure reagents and following established techniques 8 . The new results show a þ5.5 to þ17.8 range in 1Hf (defined in Fig. 1). The extreme 1Hf values for the data presented here occur on the ASP plateau (þ5.5) and in the westernmost AAD (þ17.8), and are within the range of values measured previously in those areas [9][10][11][12] . Broadly speaking, Hf and ...

No abstract