The effects of dialysate calcium prescription on mortality outcomes in incident patients on hemodialysis.

Background: The appropriate prescription of dialysate calcium concentration for hemodialysis is debated. We investigated the association between dialysate calcium and all-cause, cardiovascular mortality and sudden cardiac death.

Methods: In this historical cohort study, we included adult incident hemodialysis patients who initiated dialysis between 1 January 2010 and 30 June 2017 who survived for at least 6 months (grace period).

Calcifying Coccolithophore: An Evolutionary Advantage Against Extracellular Oxidative Damage.

The evolutionary advantages afforded by phytoplankton calcification remain enigmatic. In this work, fluoroelectrochemical experiments reveal that the presence of a CaCO shell of a naturally calcifying coccolithophore, Coccolithus braarudii, offers protection against extracellular oxidants as measured by the time required for the switch-off in their chlorophyll signal, compared to the deshelled equivalents, suggesting the shift toward calcification offers some advantages for survival in the surface of radical-rich seawater.

Phytoplankton responses to dust addition in the Fe-Mn co-limited eastern Pacific sub-Antarctic differ by source region.

The seasonal availability of light and micronutrients strongly regulates productivity in the Southern Ocean, restricting biological utilization of macronutrients and CO drawdown. Mineral dust flux is a key conduit for micronutrients to the Southern Ocean and a critical mediator of multimillennial-scale atmospheric CO oscillations. While the role of dust-borne iron (Fe) in Southern Ocean biogeochemistry has been examined in detail, manganese (Mn) availability is also emerging as a potential driver of past, present, and future Southern Ocean biogeochemistry.

AI facilitated fluoro-electrochemical phytoplankton classification.

Marine phytoplankton is extremely diverse. Counting and characterising phytoplankton is essential for understanding climate change and ocean health not least since phytoplankton extensively biomineralize carbon dioxide whilst generating 50% of the planet's oxygen. We report the use of fluoro-electrochemical microscopy to distinguish different taxonomies of phytoplankton by the quenching of their chlorophyll-a fluorescence using chemical species oxidatively electrogenerated in seawater.

Rapid Opto-electrochemical Differentiation of Marine Phytoplankton.

The use of electro-generated oxidants in seawater facilitates the discrimination of different plankton groups via monitoring the decay in real time of their chlorophyll-a (chl-a) fluorescence signals following potentiostatic initiation of electrolysis in their vicinity (Yang M.Chem. Sci.

Quantifying the Extent of Calcification of a Coccolithophore Using a Coulter Counter.

Although, in principle, the Coulter Counter technique yields an absolute measure of particle volume, in practice, calibration is near-universally employed. For regularly shaped and non-biological samples, the use of latex beads for calibration can provide sufficient accuracy. However, this is not the case with particles encased in biogenically formed calcite.

A Conceptual Approach to Partitioning a Vertical Profile of Phytoplankton Biomass Into Contributions From Two Communities.

We describe an approach to partition a vertical profile of chlorophyll-a concentration into contributions from two communities of phytoplankton: one (community 1) that resides principally in the turbulent mixed-layer of the upper ocean and is observable through satellite visible radiometry; the other (community 2) residing below the mixed-layer, in a stably stratified environment, hidden from the eyes of the satellite. The approach is tuned to a time-series of profiles from a Biogeochemical-Argo float in the northern Red Sea, selected as its location transitions from a deep mixed layer in winter (characteristic of vertically well-mixed systems) to a shallow mixed layer in the summer with a deep chlorophyll-a maximum (characteristic of vertically stratified systems). The approach is extended to reproduce profiles of particle backscattering, by deriving the chlorophyll-specific backscattering coefficients of the two communities and a background coefficient assumed to be dominated by non-algal particles in the region.

Opto-Electrochemical Dissolution Reveals Coccolith Calcium Carbonate Content.

Coccoliths are plates of biogenic calcium carbonate secreted by calcifying marine phytoplankton; annually these phytoplankton are responsible for exporting >1 billion tonnes (10  g) of calcite to the deep ocean. Rapid and reliable methods for assessing the degree of calcification are technically challenging because the coccoliths are micron sized and contain picograms (pg) of calcite. Here we pioneer an opto-eletrochemical acid titration of individual coccoliths which allows 3D reconstruction of each individual coccolith via in situ optical imaging enabling direct inference of the coccolith mass.

Radiometric approach for the detection of picophytoplankton assemblages across oceanic fronts.

Cell abundances of Prochlorococcus, Synechococcus, and autotrophic picoeukaryotes were estimated in surface waters using principal component analysis (PCA) of hyperspectral and multispectral remote-sensing reflectance data. This involved the development of models that employed multilinear correlations between cell abundances across the Atlantic Ocean and a combination of PCA scores and sea surface temperatures. The models retrieve high Prochlorococcus abundances in the Equatorial Convergence Zone and show their numerical dominance in oceanic gyres, with decreases in Prochlorococcus abundances towards temperate waters where Synechococcus flourishes, and an emergence of picoeukaryotes in temperate waters.

Development of a bio-optical model for the Barents Sea to quantitatively link glider and satellite observations.

A bio-optical model for the Barents Sea is determined from a set of observations of inherent optical properties (IOPs) and associated biogeochemical analyses. The bio-optical model provides a pathway to convert commonly measured parameters from glider-borne sensors (CTD, optical triplet sensor-chlorophyll and CDOM fluorescence, backscattering coefficients) to bulk spectral IOPs (absorption, attenuation and backscattering). IOPs derived from glider observations are subsequently used to estimate remote sensing reflectance spectra that compare well with coincident satellite observations, providing independent validation of the general applicability of the bio-optical model.

Bio-optical evidence for increasing dominance in the Barents Sea.

Increasing contributions of prymnesiophytes such as and to Barents Sea (BS) phytoplankton production have been suggested based on observations of phytoplankton community composition, but the scattered and discontinuous nature of these records confounds simple inference of community change or its relationship to salient environmental variables. However, provided that meaningful assessments of phytoplankton community composition can be inferred based on their optical characteristics, ocean-colour records offer a potential means to develop a synthesis between sporadic observations. Existing remote-sensing algorithms to retrieve phytoplankton functional types based on chlorophyll-a () concentration or indices of pigment packaging may, however, fail to distinguish from other blooms of phytoplankton with high pigment packaging, such as diatoms.

Vertical structure in chlorophyll profiles: influence on primary production in the Arctic Ocean.

Subsurface chlorophyll maximum (SCM) layers are prevalent throughout the Arctic Ocean under stratified conditions and are observed both in the wake of retreating sea ice and in thermally stratified waters. The importance of these layers on the overall productivity of Arctic pelagic ecosystems has been a source of debate. In this study, we consider the three principal factors that govern productivity within SCMs: the shape of the chlorophyll profile, the photophysiological characteristics of phytoplankton and the availability of light in the layer.

Special Issue on Remote Sensing of Ocean Color: Theory and Applications.

The editorial team are delighted to present this Special Issue of focused on Remote Sensing of Ocean Color: Theory and Applications. We believe that this is a timely opportunity to showcase current developments across a broad range of topics in ocean color remote sensing (OCRS). Although the field is well-established, in this Special Issue we are able to highlight advances in the applications of the technology, our understanding of the underpinning science, and its relevance in the context of monitoring climate change and engaging public participation.

Reconciling models of primary production and photoacclimation [Invited].

Primary production and photoacclimation models are two important classes of physiological models that find applications in remote sensing of pools and fluxes of carbon associated with phytoplankton in the ocean. They are also key components of ecosystem models designed to study biogeochemical cycles in the ocean. So far, these two classes of models have evolved in parallel, somewhat independently of each other.

Evaluating the diagnostic accuracy of maximal aortic diameter, length and volume for prediction of aortic dissection.

Objective: Management of thoracic aortic aneurysms (TAAs) comprises regular diameter follow-up until the indication criterion for prophylactic surgery is reached. However, this approach is unable to predict the majority of acute type A aortic dissections (ATAADs). The current study aims to evaluate the diagnostic accuracy of ascending aortic diameter, length and volume for occurrence of ATAAD.

Uganda Genome Resource Enables Insights into Population History and Genomic Discovery in Africa.

Genomic studies in African populations provide unique opportunities to understand disease etiology, human diversity, and population history. In the largest study of its kind, comprising genome-wide data from 6,400 individuals and whole-genome sequences from 1,978 individuals from rural Uganda, we find evidence of geographically correlated fine-scale population substructure. Historically, the ancestry of modern Ugandans was best represented by a mixture of ancient East African pastoralists.

Fluoro-electrochemical microscopy reveals group specific differential susceptibility of phytoplankton towards oxidative damage.

In the vicinity of an electrode creating a highly oxidising environment the fluorescence - arising from the presence of chlorophyll-a - of single cellular phytoplankton becomes inhibited. Even for phytoplankton that are very comparable in size ( 2-20 μm) the rate of this (electro)chemically induced fluorescence inhibition differs significantly between phytoplankton species; the fluorescence signal of the freshwater algae turns off ∼70 times faster than that of the marine coccolithophore . The varying behaviour reflects the differing susceptibility of these globally important phytoplankton species towards extreme levels of radical induced oxidative stress, indicating the physical and chemical properties of the plankton cell wall and membrane are very different between species, and are important in determining their susceptibility.

Marine microbial metagenomes sampled across space and time.

Recent advances in understanding the ecology of marine systems have been greatly facilitated by the growing availability of metagenomic data, which provide information on the identity, diversity and functional potential of the microbial community in a particular place and time. Here we present a dataset comprising over 5 terabases of metagenomic data from 610 samples spanning diverse regions of the Atlantic and Pacific Oceans. One set of metagenomes, collected on GEOTRACES cruises, captures large geographic transects at multiple depths per station.

Single cell genomes of Prochlorococcus, Synechococcus, and sympatric microbes from diverse marine environments.

Prochlorococcus and Synechococcus are the dominant primary producers in marine ecosystems and perform a significant fraction of ocean carbon fixation. These cyanobacteria interact with a diverse microbial community that coexists with them. Comparative genomics of cultivated isolates has helped address questions regarding patterns of evolution and diversity among microbes, but the fraction that can be cultivated is miniscule compared to the diversity in the wild.

Basin-Scale Observations of Monoterpenes in the Arctic and Atlantic Oceans.

We report novel in situ speciated observations of monoterpenes (α- and β-pinene, myrcene, δ3-carene, ocimene, limonene) in seawater and air during three cruises in the Arctic and Atlantic Oceans, in/over generally oligotrophic waters. Oceanic concentrations of the individual monoterpenes ranged from below the detection limit of <1 pmol L to 5 pmol L, with average concentrations of between 0.5 and 2.

Variation in head and neck cancer care in the Netherlands: A retrospective cohort evaluation of incidence, treatment and outcome.

Background: To explore variation in numbers and treatment between hospitals that treat head and neck cancer (HNC) in the Netherlands.

Material And Methods: Patient, tumor and treatment characteristics were collected from the Netherlands Cancer Registry, while histopathological features were obtained by linkage to the national pathology record register PALGA. Inter-hospital variation in volume, stage, treatment, pathologically confirmed loco-regional recurrence and overall survival rate was evaluated by tumor site.

The Allelic Landscape of Human Blood Cell Trait Variation and Links to Common Complex Disease.

Many common variants have been associated with hematological traits, but identification of causal genes and pathways has proven challenging. We performed a genome-wide association analysis in the UK Biobank and INTERVAL studies, testing 29.5 million genetic variants for association with 36 red cell, white cell, and platelet properties in 173,480 European-ancestry participants.

Determinants of agreement between proposed therapeutic windows of platelet function tests in vulnerable patients.

Aims: Therapeutic windows for residual platelet reactivity in patients with coronary artery disease on P2Y12 inhibitors were proposed in a consensus document. We aimed to explore the level of agreement between windows for different platelet function tests (PFTs) used to classify patients in low, optimal, and high on-treatment platelet reactivity categories, and to identify variables contributing to the level of agreement.

Methods And Results: In this explorative clinical study, the VerifyNow P2Y12, Multiplate adenosine diphosphate (ADP), and light transmission aggregometry (LTA) 20 μmol/L ADP were performed simultaneously in 145 consecutive vulnerable patients.