Coccolithophore fluxes in the open tropical North Atlantic: influence of thermocline depth, Amazon water, and Saharan dust

Coccolithophores are calcifying phytoplankton and major contributors to both the organic and inorganic oceanic carbon pumps. Their export fluxes, species composition, and seasonal patterns were determined in two sediment trap moorings (M4 at 12 degrees N, 49 degrees W and M2 at 14 degrees N, 37 degrees W) collecting settling particles synchronously from October 2012 to November 2013 at 1200 m of water depth in the open equatorial North Atlantic. The two trap locations showed a similar seasonal pattern in total coccolith export fluxes and a predominantly tropical coccolithophore settling assemblage. Species fluxes were dominated throughout the year by lower photic zone (LPZ) taxa (Florisphaera profunda, Gladiolithus flabellatus) but also included upper photic zone (UPZ) taxa (Umbellosphaera spp., Rhabdosphaera spp., Umbilicosphaera spp., Helicosphaera spp.). The LPZ flora was most abundant during fall 2012, whereas the UPZ flora was more important during summer. In spite of these similarities, the western part of the study area produced persistently higher fluxes, averaging 241 x 10(7) +/- 76 x 10(7) coccoliths m(-2) d(-1) at station M4 compared to only 66 x 10(7) +/- 31 x 10(7) coccoliths m(-2) d(-1) at station M2. Higher fluxes at M4 were mainly produced by the LPZ species, favoured by the westward deepening of the thermocline and nutricline. Still, most UPZ species also contributed to higher fluxes, reflecting enhanced productivity in the western equatorial North Atlantic. Such was the case of two marked flux peaks of the more opportunistic species Gephyrocapsa muellerae and Emiliania huxleyi in January and April 2013 at M4, indicating a fast response to the nutrient enrichment of the UPZ, probably by wind-forced mixing. Later, increased fluxes of G. oceanica and E. huxleyi in October-November 2013 coincided with the occurrence of Amazon-River-affected surface waters. Since the spring and fall events of 2013 were also accompanied by two dust flux peaks, we propose a scenario in which atmospheric dust also provided fertilizing nutrients to this area. Enhanced surface buoyancy associated with the river plume indicates that the Amazon acted not only as a nutrient source, but also as a surface density retainer for nutrients supplied from the atmosphere. Nevertheless, lower total coccolith fluxes during these events compared to the maxima recorded in November 2012 and July 2013 indicate that transient productivity by opportunistic species was less important than "background" tropical productivity in the equatorial North Atlantic. This study illustrates how two apparently similar sites in the tropical open ocean actually differ greatly in ecological and oceanographic terms. The results presented here provide valuable insights into the processes governing the ecological dynamics and the downward export of coccolithophores in the tropical North Atlantic.Netherlands Organization for Scientific Research (NWO) [822.01.008]; European Research Council (ERC) [311152]; University of Bremen; European Union [600411]info:eu-repo/semantics/publishedVersio

Reliability of Observational Assessment Methods for Outcome-based Assessment of Surgical Skill: Systematic Review and Meta-analyses

BACKGROUND: Reliable performance assessment is a necessary prerequisite for outcome-based assessment of surgical technical skill. Numerous observational instruments for technical skill assessment have been developed in recent years. However, methodological shortcomings of reported studies might negatively impinge on the interpretation of inter-rater reliability. OBJECTIVE: To synthesize the evidence about the inter-rater reliability of observational instruments for technical skill assessment for high-stakes decisions. DESIGN: A systematic review and meta-analysis were performed. We searched Scopus (including MEDLINE) and Pubmed, and key publications through December, 2016. This included original studies that evaluated reliability of instruments for the observational assessment of technical skills. Two reviewers independently extracted information on the primary outcome (the reliability statistic), secondary outcomes, and general information. We calculated pooled estimates using multilevel random effects meta-analyses where appropriate. RESULTS: A total of 247 documents met our inclusion criteria and provided 491 inter-rater reliability estimates. Inappropriate inter-rater reliability indices were reported for 40% of the checklists estimates, 50% of the rating scales estimates and 41% of the other types of assessment instruments estimates. Only 14 documents provided sufficient information to be included in the meta-analyses. The pooled Cohen's kappa was.78 (95% CI 0.69-0.89, p < 0.001) and pooled proportion agreement was 0.84 (95% CI 0.71-0.96, p < 0.001). A moderator analysis was performed to explore the influence of type of assessment instrument as a possible source of heterogeneity. CONCLUSIONS AND RELEVANCE: For high-stakes decisions, there was often insufficient information available on which to base conclusions. The use of suboptimal statistical methods and incomplete reporting of reliability estimates does not support the use of observational assessment instruments for technical skill for high-stakes decisions. Interpretations of inter-rater reliability should consider the reliability index and assessment instrument used. Reporting of inter-rater reliability needs to be improved by detailed descriptions of the assessment process

The cost of monitoring in time-based prospective memory

Time-based prospective memory (TBPM) involves remembering to perform actions at specific times in the future. Several studies suggest that monetary consequences improve prospective remembering; however, the effect of monetary consequences on strategic time monitoring (i.e., clock-checking behaviour) in TBPM is still unknown. The present study investigated how the monetary costs on clock-checking affected TBPM accuracy and strategic time monitoring. Participants performed an ongoing lexical decision task while carrying out a TBPM task every two minutes. Motivational incentives were manipulated across three experimental conditions: a single-cost condition in which missed TBPM responses led to monetary deductions, a double-cost condition in which both missed responses and time monitoring led to monetary deductions, and a control condition with no monetary deductions. Overall, the findings indicated that monetary costs on clock-checking prompted more parsimonious strategic time monitoring behaviour, which negatively impacted TBPM accuracy. These results emphasize the importance of weighing the motivational aspects involved in strategic monitoring, shedding light on the complex relationship between clock-checking behaviour, its consequences, and TBPM performance.</p

Cocos (Keeling) Corals Reveal 200 Years of Multidecadal Modulation of Southeast Indian Ocean Hydrology by Indonesian Throughflow

The only low latitude pathway of heat and salt from the Pacific Ocean to the Indian Ocean, known as Indonesian Throughflow (ITF), has been suggested to modulate Global Mean Surface Temperature (GMST) warming through redistribution of surface Pacific Ocean heat. ITF observations are only available since ~1990s, and thus, its multidecadal variability on longer time scales has remained elusive. Here we present a 200 year bimonthly record of geochemical parameters (d 18 O-Sr/Ca) measured on Cocos (Keeling) corals tracking sea surface temperature (SST; Sr/Ca) and sea surface salinity (SSS; seawater-d 18 O-d 18 O sw ) in the southeastern tropical Indian Ocean (SETIO). Our results show that SETIO SSS and d 18 O sw were impacted by ITF transport over the past 60 years, and therefore, reconstructions of Cocos d 18 O sw hold information on past ITF variability on longer time spans. Over the past 200 years ITF leakage into SETIO is dominated by the interannual climate modes of the Pacific Ocean (El Niño—Southern Oscillation) and Indian Ocean (Indian Ocean Dipole). Pacific decadal climate variability (represented by the Pacific Decadal Oscillation) significantly impacted ITF strength over the past 200 years determining the spatiotemporal SST and SSS advection into the Indian Ocean on multidecadal time scales. A comparison of our SETIO d 18 O sw record to GMST shows that ITF transport varied in synchrony with global warming rate, being predominantly high/low during GMST warming slowdown/acceleration, respectively. This hints toward an important role for the ITF in global warming rate modulation

Genetic Mapping in Tetraploid Alfalfa: Results and Prospects

Among the difficulties of improving forages is their perennial nature, which necessarily requires long selection cycles to fully evaluate genotypes. Further, traits of particular importance—yield and winter hardiness—are difficult to assess on single plants, necessitating evaluation of progeny, which is both time consuming and expensive. Because of this, yield of many forages, and particularly alfalfa, has not improved substantially over the past 25 years (Riday and Brummer, 2002). Winter hardiness often has a negative correlation with autumn growth, although some evidence suggests this is not always true (Brummer et al., 2000). One way to overcome some of these limitations may be through the use of genetic markers to help select desirable genotypes. The objective of this experiment was to test the hypothesis that quantitative trait loci (QTL) for complex agronomic traits could be identified in a segregating tetraploid alfalfa population

Controlling Silver Nanoparticle Size and Morphology with Photostimulated Synthesis

Photo-induced synthesis and control over the size and shape of colloidal silver nanoparticles is investigated in contrast to photo-stimulated aggregation of small nanoparticles into large fractal-type structures. The feasibility of light-driven nanoengineering which enables manipulation of the sizes and shapes of the isolated nanoparticles is studied by varying the amount and type of the stabilizing agent and the type of optical irradiation.Comment: 10 pages, 7 figures, 11 image

A Shift Symmetry in the Higgs Sector: Experimental Hints and Stringy Realizations

We interpret reported hints of a Standard Model Higgs boson at ~ 125 GeV in terms of high-scale supersymmetry breaking with a shift symmetry in the Higgs sector. More specifically, the Higgs mass range suggested by recent LHC data extrapolates, within the (non-supersymmetric) Standard Model, to a vanishing quartic Higgs coupling at a UV scale between 10^6 and 10^18 GeV. Such a small value of lambda can be understood in terms of models with high-scale SUSY breaking if the Kahler potential possesses a shift symmetry, i.e., if it depends on H_u and H_d only in the combination (H_u+\bar{H}_d). This symmetry is known to arise rather naturally in certain heterotic compactifications. We suggest that such a structure of the Higgs Kahler potential is common in a wider class of string constructions, including intersecting D7- and D6-brane models and their extensions to F-theory or M-theory. The latest LHC data may thus be interpreted as hinting to a particular class of compactifications which possess this shift symmetry.Comment: v2: References added. v3: References added, published versio

The development of a measurement instrument to measure the quality of internet investor relations

The purpose of this study was to develop a measurement instrument to measure the quality of Internet investor relations (IIR). This study will aid future research to examine IIR and provide guidance to companies in the development of an IIR strategy. The development of the instrument was based on best practice guidelines issued by the Investor Relations Society, an extensive literature review and a pilot study. The result was a measurement instrument that consists of 346 attributes. Quality is assessed by measuring content as widely as possible, by including attributes to measure the accessibility, navigation and timeliness of information, and by allowing for the measurement of attributes as being partially available based on breadth, usability and timeliness considerations. The reliability and validity of the measurement instrument was confirmed on the basis of the measurement results of a sample of 85 JSE-listed companies