Synoptic-scale analysis of mechanisms driving surface chlorophyll dynamics in the North Atlantic

Several hypotheses have been proposed for the onset of the spring phytoplankton bloom in the North Atlantic. Our main objective is to examine which bottom-up processes can best predict the annual increase in surface phytoplankton concentration in the North Atlantic by applying novel phenology algorithms to ocean colour data. We construct indicator fields and time series which, in various combinations, provide models consistent with the principle dynamics previously proposed. Using a multimodel inference approach, we investigate the evidence supporting these models and how it varies in space. We show that, in terms of bottom-up processes alone, there is a dominant physical mechanism, namely mixed-layer shoaling, that best predicts the interannual variation in the initial increase in surface chlorophyll across large sectors of the North Atlantic. We further show that different regions are governed by different physical phenomena and that wind-driven mixing is a common component, with either heat flux or light as triggers. We believe these findings to be relevant to the ongoing discussion on North Atlantic bloom onset

Limiting Carleman weights and anisotropic inverse problems

In this article we consider the anisotropic Calderon problem and related inverse problems. The approach is based on limiting Carleman weights, introduced in Kenig-Sjoestrand-Uhlmann (Ann. of Math. 2007) in the Euclidean case. We characterize those Riemannian manifolds which admit limiting Carleman weights, and give a complex geometrical optics construction for a class of such manifolds. This is used to prove uniqueness results for anisotropic inverse problems, via the attenuated geodesic X-ray transform. Earlier results in dimension $n \geq 3$ were restricted to real-analytic metrics.Comment: 58 page

Age and provenance of the Cryogenian to Cambrian passive margin to foreland basin sequence of the northern Paraguay Belt, Brazil

The Paraguay Belt in central South America\ud developed in response to the collision of\ud the Amazonian craton, the São Francisco\ud craton, and the Paranapanema block. The\ud alleged “Brasiliano” age (ca. 620 Ma) of\ud orogenesis has recently been questioned by\ud paleo magnetic and radioisotopic ages that\ud indicate the closing stages of orogenesis occurred\ud well into the Cambrian. We investigated\ud the timing of deposition and source\ud areas for these sedimentary rocks overlying\ud the Amazonian craton using integrated\ud U-Pb and Hf isotope data of detrital zircons\ud from within this sequence. In total, 742 detrital\ud zircon U-Pb ages were analyzed from\ud samples taken from the base to the top of this\ud sedimentary succession. Maximum depositional\ud ages from the uppermost part of this\ud sequence of rocks, the Diamantino Formation,\ud indicate that fi nal deposition began no\ud earlier than 560 ± 13 Ma and possibly as\ud young as the Cambrian. Given that zircon\ud inheritance in these rocks continues up until\ud this age and that known Amazonian craton\ud ages are older than ca. 950 Ma, we considered\ud other potential sources for these sediments.\ud This was achieved by integrating the\ud U-Pb detrital zircon data with Hf isotopic\ud data from these zircons that have εHf values\ud ranging from –18 to 12. The εHf signature is\ud consistent, with a predominantly Amazonian\ud source until the early Neoproterozoic, at\ud which point the signal becomes signifi cantly\ud more evolved. These data, when combined\ud with other evidence discussed here, are\ud consistent with an ocean to the east of the\ud present-day Amazonian craton that did not\ud close until the latest Ediacaran–Cambrian

PASSIVATION OF SEMICONDUCTOR SURFACES FOR IMPROVED RADIATION DETECTORS: X-RAY PHOTOEMISSION ANALYSIS

Surface passivation of device-grade radiation detector materials was investigated using x-ray photoelectron spectroscopy in combination with transport property measurements before and after various chemical treatments. Specifically Br-MeOH (2% Br), KOH with NH{sub 4}F/H{sub 2}O{sub 2} and NH{sub 4}OH solutions were used to etch, reduce and oxidize the surface of Cd{sub (1-x)}Zn{sub x}Te semiconductor crystals. Scanning electron microscopy was used to evaluate the resultant microscopic surface morphology. Angle-resolved high-resolution photoemission measurements on the valence band electronic structure and core lines were used to evaluate the surface chemistry of the chemically treated surfaces. Metal overlayers were then deposited on these chemically treated surfaces and the I-V characteristics measured. The measurements were correlated to understand the effect of interface chemistry on the electronic structure at these interfaces with the goal of optimizing the Schottky barrier height for improved radiation detector devices

Exchange rate uncertainty and international portfolio flows: A multivariate GARCH-in-mean approach

This paper examines the impact of exchange rate uncertainty on different components of net portfolio flows, namely net equity and net bond flows, as well as their dynamic linkages. Specifically, a bivariate VAR GARCH-BEKK-in-mean model is estimated using bilateral monthly data for the US vis-à-vis Australia, Canada, the euro area, Japan, Sweden, and the UK over the period 1988:01-2011:12. The results indicate that the effect of exchange rate uncertainty on net equity flows is negative in the euro area, the UK and Sweden, and positive in Australia. The impact on net bond flows is also negative in all countries except Canada, where it is positive. Under the assumption of risk aversion, the findings suggest that exchange rate uncertainty induces a home bias and causes investors to reduce their financial activities to maximise returns and minimise exposure to uncertainty, this effect being stronger in the UK, the euro area and Sweden compared to Canada, Australia and Japan. Overall, the results indicate that exchange rate or credit controls on these flows can be used as a policy tool in countries with strong uncertainty effects to pursue economic and financial stability

Main motivations for CRM adoption by large portuguese companies: a principal component analysis

The motivations for an organization to adopt Customer Relationship Management (CRM) systems can be very varied, which brings an additional complexity to the adoption decision. It is important to understand the main drivers of CRM adoption so that companies can better target their investment efforts. This paper presents and discusses the main findings of a study undertaken among a sample of large Portuguese companies, identifying and discussing the main motivations for CRM systems adoption. A survey was carried out for data collection, and a Principal Component Analysis was made to identify the main motivations. The study concludes that the main motivations for adopting CRM systems are related to cost reduction, improving overall customer satisfaction, improving processes, achieving competitive advantages and improving information quality. The findings of this study can help the academic and professional community to better understand the main motivations of companies for adopting CRM systems, and also for CRM systems vendors and consultants to better address the needs of their potential clients

Pathophysiology of LV Remodeling in Survivors of STEMI Inflammation, Remote Myocardium, and Prognosis

AbstractObjectivesThe aim of this study was to investigate the clinical significance of native T1 values in remote myocardium in survivors of acute ST-segment elevation myocardial infarction (STEMI).BackgroundThe pathophysiology and prognostic significance of remote myocardium in the natural history of STEMI is uncertain. Cardiac magnetic resonance (CMR) reveals myocardial function and pathology. Native T1 (relaxation time in ms) is a fundamental magnetic resonance tissue property determined by water content and cellularity.ResultsA total of 300 STEMI patients (mean age 59 years; 74% male) gave informed consent. A total of 288 STEMI patients had evaluable native T1 CMR, and 267 patients (91%) had follow-up CMR at 6 months. Health outcome information was obtained for all of the participants (median follow-up 845 days). Infarct size was 18 ± 13% of left ventricular (LV) mass. Two days post-STEMI, native T1 was lower in remote myocardium than in the infarct zone (961 ± 25 ms vs. 1,097 ± 52 ms; p < 0.01). In multivariable regression, incomplete ST-segment resolution was associated with myocardial remote zone native T1 (regression coefficient 9.42; 95% confidence interval [CI]: 2.37 to 16.47; p = 0.009), as were the log of the admission C-reactive protein concentration (3.01; 95% CI: 0.016 to 5.85; p = 0.038) and the peak monocyte count (10.20; 95% CI: 0.74 to 19.67; p = 0.035). Remote T1 at baseline was associated with log N-terminal pro–B-type natriuretic peptide at 6 months (0.01; 95% CI: 0.00 to 0.02; p = 0.002; n = 151) and the change in LV end-diastolic volume from baseline to 6 months (0.13; 95% CI: 0.01 to 0.24; p = 0.035). Remote zone native T1 was independently associated with post-discharge major adverse cardiac events (n = 20 events; hazard ratio: 1.016; 95% CI: 1.000 to 1.032; p = 0.048) and all-cause death or heart failure hospitalization (n = 30 events during admission and post-discharge; hazard ratio: 1.014; 95% CI: 1.000 to 1.028; p = 0.049).ConclusionsReperfusion injury and inflammation early post-MI was associated with remote zone T1, which in turn was independently associated with LV remodeling and adverse cardiac events post-STEMI. (Detection and Significance of Heart Injury in ST Elevation Myocardial Infarction [BHF MR-MI]; NCT02072850

Possible patterns of marine primary productivity during the Great Ordovician Biodiversification Event

Following the appearance of numerous animal phyla during the ‘Cambrian Explosion’, the ‘Great Ordovician Biodiversification Event’ (GOBE) records their rapid diversification at the lower taxonomic levels, constituting the most significant rise in biodiversity in Earth's history. Recent studies suggest that the rapid rise in phytoplankton diversity observed at the Cambrian–Ordovician boundary may have profoundly restructured marine trophic chains, paving the way for the subsequent flourishing of plankton-feeding groups during the Ordovician. Unfortunately, the fossil record of plankton is incomplete. Its smaller members represent the bulk of the modern marine biomass, but they are usually not documented in Palaeozoic sediments, preventing any definitive assumption with regard to an eventual correlation between biodiversity and biomass at that time. Here, we use an up-to-date ocean general circulation model with biogeochemical capabilities (MITgcm) to simulate the spatial patterns of marine primary productivity throughout the Ordovician, and we compare the model output with available palaeontological and sedimentological data