Role of dissolved nitrate and phosphate in isolates of Mesodinium rubrum and toxin-producing Dinophysis acuminata

Mesodinium rubrum (as prey) is a critical component, in addition to light, for growth and toxin production by the mixotrophic dinoflagellate Dinophysis acuminata. Little is known, however, about the role that dissolved inorganic nutrients play in this predator-prey relationship and system toxicity. A series of experiments were conducted to investigate the possible uptake of dissolved nitrate and phosphate by (1) D. acuminata starved of prey, (2) D. acuminata feeding on M. rubrum, and (3) M. rubrum grown in nutritionally modified medium. All single-clone or mixed cultures were monitored for dissolved and particulate nutrient levels over the growth cycle, as well as for growth rate, biomass, and toxin production when appropriate. Dinophysis acuminata did not utilize dissolved nitrate or phosphate in the medium under nutrient-enriched or nutrientreduced regimes, in the absence or presence of prey, or during any growth phase monitored. Changes in particulate phosphorus and nitrogen in D. acuminata were instead strongly influenced by the consumption of M. rubrum prey, and these levels quickly stabilized once prey were no longer available. Mesodinium rubrum, in contrast, rapidly assimilated dissolved nitrate and phosphate, with maximum uptake rates of 1.38 pmol N cell(-1) d(-1) and 1.63 pmol P cell(-1) d(-1), respectively. While D. acuminata did not benefit directly from the dissolved nitrate and phosphate, its growth (0.37 +/- 0.01 d(-1)) and toxin production rates for okadaic acid, dinophysistoxin-1 and pectenotoxin-2 (0.1, 0.9 and 2.6 pg cell(-1) d(-1), respectively) were directly coupled to prey availability. These results suggest that while dissolved nitrate and phosphate do not have a direct effect on toxin production or retention by D. acuminata, these nutrient pools contribute to prey growth and biomass, thereby indirectly influencing D. acuminata blooms and overall toxins in the system

Diversity and dynamics of a widespread bloom of the toxic dinoflagellate Alexandrium fundyense

© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 6 (2011): e22965, doi:10.1371/journal.pone.0022965.Historically, cosmopolitan phytoplankton species were presumed to represent largely unstructured populations. However, the recent development of molecular tools to examine genetic diversity have revealed differences in phytoplankton taxa across geographic scales and provided insight into the physiology and ecology of blooms. Here we describe the genetic analysis of an extensive bloom of the toxic dinoflagellate Alexandrium fundyense that occurred in the Gulf of Maine in 2005. This bloom was notable for its intensity and duration, covering hundreds of kilometers and persisting for almost two months. Genotypic analyses based on microsatellite marker data indicate that the open waters of the northeastern U.S. harbor a single regional population of A. fundyense comprising two genetically distinct sub-populations. These subpopulations were characteristic of early- and late-bloom samples and were derived from the northern and southern areas of the bloom, respectively. The temporal changes observed during this study provide clear evidence of succession during a continuous bloom and show that selection can act on the timescale of weeks to significantly alter the representation of genotypes within a population. The effects of selection on population composition and turnover would be magnified if sexual reproduction were likewise influenced by environmental conditions. We hypothesize that the combined effects of differential growth and reproduction rates serves to reduce gene flow between the sub-populations, reinforcing population structure while maintaining the diversity of the overall regional population.This work was supported by the National Institute of Environmental Health Sciences (1-P50-ES012742 to DMA and DLE), by the National Science Foundation through the Woods Hole Center for Oceans and Human Health (OCE-0430724), and by the ECOHAB program (NOAA Grant NA06NOS4780245)

A summary of the BARREL campaigns: Technique for studying electron precipitation.

BARREL observed electron precipitation over wide range of energy and timescalesPrecipitating electron distribution is determined using spectroscopy for 19 January 2013 eventBARREL timing data has accuracy within sampling interval of 0.05 s

Can translation invariant systems exhibit a Many-Body Localized phase?

This note is based on a talk by one of us, F. H., at the conference PSPDE II, Minho 2013. We review some of our recent works related to (the possibility of) Many-Body Localization in the absence of quenched disorder (in particular arXiv:1305.5127,arXiv:1308.6263,arXiv:1405.3279). In these works, we provide arguments why systems without quenched disorder can exhibit `asymptotic' localization, but not genuine localization.Comment: To appear in the Proceedings of the conference Particle systems and PDE's - II, held at the Center of Mathematics of the University of Minho in December 201

Metrics with Prescribed Ricci Curvature near the Boundary of a Manifold

Suppose $M$ is a manifold with boundary. Choose a point $o\in\partial M$. We investigate the prescribed Ricci curvature equation \Ric(G)=T in a neighborhood of $o$ under natural boundary conditions. The unknown $G$ here is a Riemannian metric. The letter $T$ in the right-hand side denotes a (0,2)-tensor. Our main theorems address the questions of the existence and the uniqueness of solutions. We explain, among other things, how these theorems may be used to study rotationally symmetric metrics near the boundary of a solid torus $\mathcal T$. The paper concludes with a brief discussion of the Einstein equation on $\mathcal T$.Comment: 13 page

The structural invisibility of outsiders: the role of migrant labour in the meat-processing industry

This article examines the role of migrant workers in meat-processing factories in the UK. Drawing on materials from mixed methods research in a number of case study towns across Wales, we explore the structural and spatial processes that position migrant workers as outsiders. While state policy and immigration controls are often presented as a way of protecting migrant workers from work-based exploitation and ensuring jobs for British workers, our research highlights that the situation ‘on the ground’ is more complex. We argue that ‘self-exploitation’ among the migrant workforce is linked to the strategies of employers and the organisation of work, and that hyper-flexible work patterns have reinforced the spatial and social invisibilities of migrant workers in this sector. While this creates problems for migrant workers, we conclude that it is beneficial to supermarkets looking to supply consumers with the regular supply of cheap food to which they have become accustomed

Spreading, Nonergodicity, and Selftrapping: a puzzle of interacting disordered lattice waves

Localization of waves by disorder is a fundamental physical problem encompassing a diverse spectrum of theoretical, experimental and numerical studies in the context of metal-insulator transitions, the quantum Hall effect, light propagation in photonic crystals, and dynamics of ultra-cold atoms in optical arrays, to name just a few examples. Large intensity light can induce nonlinear response, ultracold atomic gases can be tuned into an interacting regime, which leads again to nonlinear wave equations on a mean field level. The interplay between disorder and nonlinearity, their localizing and delocalizing effects is currently an intriguing and challenging issue in the field of lattice waves. In particular it leads to the prediction and observation of two different regimes of destruction of Anderson localization - asymptotic weak chaos, and intermediate strong chaos, separated by a crossover condition on densities. On the other side approximate full quantum interacting many body treatments were recently used to predict and obtain a novel many body localization transition, and two distinct phases - a localization phase, and a delocalization phase, both again separated by some typical density scale. We will discuss selftrapping, nonergodicity and nonGibbsean phases which are typical for such discrete models with particle number conservation and their relation to the above crossover and transition physics. We will also discuss potential connections to quantum many body theories.Comment: 13 pages in Springer International Publishing Switzerland 2016 1 M. Tlidi and M. G. Clerc (eds.), Nonlinear Dynamics: Materials, Theory and Experiment, Springer Proceedings in Physics 173. arXiv admin note: text overlap with arXiv:1405.112

Evaporation induced flow inside circular wells

Flow field and height averaged radial velocity inside a droplet evaporating in an open circular well were calculated for different modes of liquid evaporation.Comment: 5 page, 3 figures, submitted to European Physical Journal

Budgeting for Environmental Health Services in Healthcare Facilities: A Ten-Step Model for Planning and Costing

Environmental health services (EHS) in healthcare facilities (HCFs) are critical for safe care provision, yet their availability in low- and middle-income countries is low. A poor understanding of costs hinders progress towards adequate provision. Methods are inconsistent and poorly documented in costing literature, suggesting opportunities to improve evidence. The goal of this research was to develop a model to guide budgeting for EHS in HCFs. Based on 47 studies selected through a systematic review, we identified discrete budgeting steps, developed codes to define each step, and ordered steps into a model. We identified good practices based on a review of additional selected guidelines for costing EHS and HCFs. Our model comprises ten steps in three phases: planning, data collection, and synthesis. Costing-stakeholders define the costing purpose, relevant EHS, and cost scope; assess the EHS delivery context; develop a costing plan; and identify data sources (planning). Stakeholders then execute their costing plan and evaluate the data quality (data collection). Finally, stakeholders calculate costs and disseminate findings (synthesis). We present three hypothetical costing examples and discuss good practices, including using costing frameworks, selecting appropriate indicators to measure the quantity and quality of EHS, and iterating planning and data collection to select appropriate costing approaches and identify data gaps