A tale of three islands: Downstream natural iron fertilization in the Southern Ocean

Iron limitation of primary productivity prevails across much of the Southern Ocean but there are exceptions; in particular, the phytoplankton blooms associated with the Kerguelen Plateau, Crozet Islands and South Georgia. These blooms occur annually, fertilized by iron and nutrient-rich shelf waters that are transported downstream from the islands. Here we use a highresolution (1/12°) ocean general circulation model and Lagrangian particle tracking to investigate whether inter-annual variability in the potential lateral advection of iron, could explain the inter-annual variability in the spatial extent of the blooms. Comparison with ocean color data, 1998 to 2007, suggests that iron fertilization via advection can explain the extent of each island's annual bloom, but only the inter-annual variability of the Crozet bloom. The area that could potentially be fertilized by iron from Kerguelen was much larger than the bloom, suggesting that there is another primary limiting factor, potentially silicate, that controls the inter-annual variability of bloom spatial extent. For South Georgia, there are differences in the year-to-year timing of advection and consequently fertilization, but no clear explanation of the inter-annual variability observed in the bloom's spatial extent has been identified. The model results suggest that the Kerguelen and Crozet blooms are terminated by nutrient exhaustion, probably iron and or silicate, whereas the deepening of the mixed layer in winter terminates the South Georgia bloom. Therefore, iron fertilization via lateral advection alone can explain the annual variability of the Crozet bloom, but not fully that of the Kerguelen and South Georgia blooms. This article is protected by copyright. All rights reserved

Could the Madagascar bloom be fertilized by Madagascan iron?

In the oligotrophic waters to the east of Madagascar a large phytoplankton bloom is found to occur in late austral summer. This bloom is composed of nitrogen fixers and can cover up to ∼1% of the world's ocean surface area. Satellite observations show that its spatial structure is closely tied to the underlying mesoscale eddy field in the region. The causes of the bloom and its temporal behavior (timing of its initiation and termination) and spatial variability are poorly understood, in part due to a lack of in situ observations. Here an eddy resolving 1/12˚ resolution ocean general circulation model and Lagrangian particle tracking are used to examine the hypothesis that iron from sediments around Madagascar could be advected east by the mesoscale eddy field to fertilize the bloom, and that variability in advection could explain the significant interannual variability in the spatial extent of the bloom. The model results suggest that this is indeed possible and furthermore imply that the bloom could be triggered by warming of the mixed layer, leading to optimal conditions for nitrogen fixers to grow, while its termination could be due to iron exhaustion. It is found that advection of Madagascan iron could re-supply the bloom region with this micronutrient in the period between the termination of one bloom and the initiation of the next in the following year

Far-field connectivity of the UK's four largest marine protected areas: Four of a kind?

Marine Protected Areas (MPAs) are established to conserve important ecosystems and protect marine species threatened in the wider ocean. However, even MPAs in remote areas are not wholly isolated from anthropogenic impacts. “Upstream” activities, possibly thousands of kilometers away, can influence MPAs through ocean currents that determine their connectivity. Persistent pollutants, such as plastics, can be transported from neighboring shelf regions to MPAs, or an ecosystem may be affected if larval dispersal is reduced from a seemingly remote upstream area. Thus, improved understanding of exactly where upstream is, and on what timescale it is connected, is important for protecting and monitoring MPAs. Here, we use a high-resolution (1/12°) ocean general circulation model and Lagrangian particle tracking to diagnose the connectivity of four of the UK's largest MPAs: Pitcairn; South Georgia and Sandwich Islands; Ascension; and the British Indian Ocean Territory (BIOT). We introduce the idea of a circulation “connectivity footprint”, by which MPAs are connected to upstream areas. Annual connectivity footprints were calculated for the four MPAs, taking into account seasonal and inter-annual variability. These footprints showed that, on annual timescales, Pitcairn was not connected with land, whereas there was increasing connectivity for waters reaching South Georgia, Ascension, and, especially, BIOT. BIOT also had a high degree of both seasonal and inter-annual variability, which drastically changed its footprint, year-to-year. We advocate that such connectivity footprints are an inherent property of all MPAs, and need to be considered when MPAs are first proposed or their viability as refuges evaluated

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

b-Jet Identification in the D0 Experiment

Algorithms distinguishing jets originating from b quarks from other jet flavors are important tools in the physics program of the D0 experiment at the Fermilab Tevatron p-pbar collider. This article describes the methods that have been used to identify b-quark jets, exploiting in particular the long lifetimes of b-flavored hadrons, and the calibration of the performance of these algorithms based on collider data.Comment: submitted to Nuclear Instruments and Methods in Physics Research

Search for the standard model Higgs boson in tau final states

We present a search for the standard model Higgs boson using hadronically decaying tau leptons, in 1 inverse femtobarn of data collected with the D0 detector at the Fermilab Tevatron ppbar collider. We select two final states: tau plus missing transverse energy and b jets, and tau+ tau- plus jets. These final states are sensitive to a combination of associated W/Z boson plus Higgs boson, vector boson fusion and gluon-gluon fusion production processes. The observed ratio of the combined limit on the Higgs production cross section at the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of 115 GeV.Comment: publication versio

Analysis of the modes of energy consumption of the complex of an incoherent scattering of the institute of ionosphere of national academy of sciences and the ministry of education and science of Ukraine

У даній статті представлені результати аналізу режимів енергоспоживання комплексу некогерентного розсіяння Інституту іоносфери НАН і МОН України з метою вирішення проблеми підвищення енергоефективності науково-дослідного комплексу та створення енергоефективної системи електропостачання, яка забезпечить стійку роботу наукового обладнання для виконання дослідницьких програм НАН України. Описана система електроживлення комплексу та режими енергоспоживання комплексу. Описано пристрої радарної системи, а також найбільш потужні споживачі електроенергії, які споживають електроенергію на експериментальні і господарські потреби. Проаналізовано енергоспоживання комплексу некогерентного розсіяння за 2013 р. Отримано і представлено графіки середньої споживаної потужності (середньодобовий показник) і середньої споживаної потужності в режимі вимірювань. Описана доцільність проведення робіт з оптимізації енергопостачання науково-дослідного комплексу Інституту іоносфери. Запропоновано можливі заходи для зниження економічної вартості проведення експериментів з дослідження іоносфери науково-дослідного комплексу некогерентного розсіяння. Проведено аналіз робіт сучасних авторів з метою показати, що підвищення ефективності функціонування систем електропостачання є актуальною проблемою сучасних досліджень.This article presents the results of the analysis of the energy consumption modes of the incoherent scattering complex of the Institute of Ionosphere of the National Academy of Sciences and the Ministry of Education and Science of Ukraine to solve the problem of increasing the energy efficiency of a research complex and creating an energy efficient power supply system that will ensure the sustainability of scientific equipment for research programs of the National Academy of Sciences of Ukraine. The system of power supply of the complex and modes of power consumption of the complex are described. The devices of the radar system are described, as well as the most powerful consumers of electricity, which consume electricity for experimental and economic needs. The energy consumption of the incoherent scattering complex in 2013 is analyzed. Graphs of the average power consumption (daily average) and average power consumption in measurement modes were obtained and presented. The feasibility of work to optimize the energy supply of the research complex of the institute of the ionosphere is described. Possible measures are proposed to reduce the economic cost of conducting experiments on the study of the ionosphere of an incoherent scattering research complex. The analysis of the works of modern authors i s carried out in order to show that increasing the efficiency of the power supply systems is an actual problem of modern research

US acculturation and poor sleep among an intergenerational cohort of adult Latinos in Sacramento, California

Acculturation may shape the disproportionate burden of poor sleep among Latinos in the United States. Existing studies are limited by unidimensional acculturation proxies that are incapable of capturing cultural complexities across generations. Understanding how acculturation relates to sleep may lead to the identification of modifiable intervention targets. We used multivariable regression and latent class methods to examine cross-sectional associations between a validated multidimensional scale of US acculturation and self-reported poor sleep measures. We analyzed an intergenerational cohort: first-generation (GEN1) older Latinos (Sacramento Area Latino Study on Aging; N = 1,716; median age: 69.5) and second-generation (GEN2) middle-aged offspring and relatives of GEN1 (Niños Lifestyle and Diabetes Study; N = 670; median age: 54.0) in Sacramento, California. GEN1 with high US acculturation, compared with high acculturation towards another origin/ancestral country, had less restless sleep (prevalence ratio [PR] [95% confidence interval (CI)]: 0.67 [0.54, 0.84]) and a higher likelihood of being in the best sleep class than the worst (OR [95% CI]: 1.62 [1.09, 2.40]), but among nonmanual occupations, high intergenerational US acculturation was associated with more general fatigue (PR [95% CI: 1.86 [1.11, 3.10]). GEN2 with high intergenerational US acculturation reported shorter sleep (PR [95% CI]: 2.86 [1.02, 7.99]). High US acculturation shaped sleep differentially by generation, socioeconomic context, and intergenerational acculturative status. High US acculturation was associated with better sleep among older, lower socioeconomic Latinos, but with shorter sleep duration among middle-aged, higher socioeconomic Latinos; results also differed by parental acculturation status. Upon replication, future studies should incorporate prospective and intergenerational designs to uncover sociobehavioral pathways by which acculturation may shape sleep to ultimately inform intervention efforts

Search for the associated production of a b quark and a neutral supersymmetric Higgs boson which decays to tau pairs

We report results from a search for production of a neutral Higgs boson in association with a $b$ quark. We search for Higgs decays to $\tau$ pairs with one $\tau$ subsequently decaying to a muon and the other to hadrons. The data correspond to 2.7fb$^{-1}$ of \ppbar collisions recorded by the D0 detector at $\sqrt{s} = 1.96$TeV. The data are found to be consistent with background predictions. The result allows us to exclude a significant region of parameter space of the minimal supersymmetric model.Comment: Submitted to Phys. Rev. Letter

Evidence for global cooling in the Late Cretaceous.

The Late Cretaceous ‘greenhouse’ world witnessed a transition from one of the warmest climates of the past 140 million years to cooler conditions, yet still without significant continental ice. Low-latitude sea surface temperature (SST) records are a vital piece of evidence required to unravel the cause of Late Cretaceous cooling, but high-quality data remain illusive. Here, using an organic geochemical palaeothermometer (TEX86), we present a record of SSTs for the Campanian–Maastrichtian interval (~83–66¿Ma) from hemipelagic sediments deposited on the western North Atlantic shelf. Our record reveals that the North Atlantic at 35¿°N was relatively warm in the earliest Campanian, with maximum SSTs of ~35¿°C, but experienced significant cooling (~7¿°C) after this to <~28¿°C during the Maastrichtian. The overall stratigraphic trend is remarkably similar to records of high-latitude SSTs and bottom-water temperatures, suggesting that the cooling pattern was global rather than regional and, therefore, driven predominantly by declining atmospheric pCO2 levels