An Overview of the Northern Gulf of Mexico Ecosystem

The Gulf of Mexico is a large marine ecosystem (LME) bordered by the southern United States, Mexico, and Cuba. This general overview of its northern portion covers physiography, significant oceanographic features, the influence of major rivers and freshwater, biological productivity, and food web characteristics. It then describes the pelagic and benthic components of the major habitats: oceanic (continental slope and abyssal plain), continental shelf and bays, estuaries, and marshes, with descriptions of prominent processes and some dominant organisms. For each habitat several species from a variety of trophic levels are introduced and their general role in the ecosystem discussed. In 2010 the northern portion of the Gulf was the site of the largest U.S. marine oil spill in history and is now the focus of an unprecedented restoration effort. Successful restoration of the northern Gulf will depend on an integrated view of this LME and the forces that maintain and change it. This introduction to the northern Gulf marine ecosystem should be useful for policy makers, informing decisions on proposed restoration actions

Vertical distribution of microbial and meiofaunal populations in sediments of a natural coastal hydrocarbon seep

We studied the vertical distribution of microbes and meiofauna in natural hydrocarbon seep sediments to determine if there was a relationship between profiles of benthic trophic structure and the unique biogeochemical conditions present at the seep. Three stations in the Santa Barbara Channel represented a gradient of natural petroleum seepage, from very active, to moderate, to none. Seasonal differences were examined by sampling in the three major oceanographic seasons, upwelling (April), mixed (July), and Davidson (December). Densities of microbes and meiofauna were highest in July, and decreased in winter. All population sizes decreased with increasing depth in the sediment. Harpacticoids and Chl a were practically restricted to the surface sediments. Harpacticoids and Chl a were more dense (number per unit volume or strata of sediment) and abundant (number per unit area of sediment or sum of the strata) at the comparison site than at the seep sites. Density and abundance of nematodes, bacteria cell counts, and bacterial biomass were greater at the station with the most active seepage rates. Bacterial biovolumes appeared constant among sediment depths and stations, but cell biovolumes were larger in July. The data are consistent with the hypothesis that organic enrichment via petroleum utilization is responsible for increased abundances of bacteria and nematodes at the seep. There were strong correlations between densities of harpacticoids and microalgae, and densities of nematodes and bacteria. These links indicate that seeping petroleum might have an enhanced effect on the detrital (bacterial based) food web, but a toxic effect on the grazing (microalgal based) food web

Temporal variability and the relationship between benthic meiofaunal and microbial populations of a natural coastal petroleum seep

Previous studies of the Isla Vista petroleum seep in the Santa Barbara Channel found much higher abundances of macrofauna and concentrations of adenosine triphosphate (ATP) in sediments near petroleum seepage compared to those from nonseep areas. To further assess the possible effect of petroleum on organisms at the base of benthic food webs, population abundances of meiobenthos and their suspected microbial food (bacteria and diatoms) were measured biweekly for one year at three stations with differing petroleum exposure. Determinations of suspended particulate matter and the abundance and gut contents of juvenile fishes were also made at seep and nonseep stations. Nematodes and bacteria had higher abundances in areas of active petroleum seepage than in areas of moderate seepage (within 20 m) or no seepage (1.4 km away). Bacterial productivity (based on the frequency of dividing cells) was 340% greater in sediments from areas of active seepage compared to those from a nonseep station. Sediments within the seep, but away from active seepage, had rates of bacterial productivity 15 times greater than a nonseep comparison site. Densities of harpacticoid copepods and their probable principal food, diatoms, were not affected by petroleum seepage. Suspended organic matter caught in settling traps was not different between seep and nonseep stations. In addition, there was no evidence that predation pressure by juvenile fish on meiofauna was different between stations. The higher bacterial biomass and productivity in areas of petroleum seepage are consistent with the hypothesis that petroleum carbon is available for assimilation by sediment bacteria. The enhanced level of microbial carbon associated with the petroleum seep is available for consumption by benthic invertebrates and could explain the higher abundances of macrofauna and meiofauna found there

Complex exon-intron marking by histone modifications is not determined solely by nucleosome distribution

It has recently been shown that nucleosome distribution, histone modifications and RNA polymerase II (Pol II) occupancy show preferential association with exons (“exon-intron marking”), linking chromatin structure and function to co-transcriptional splicing in a variety of eukaryotes. Previous ChIP-sequencing studies suggested that these marking patterns reflect the nucleosomal landscape. By analyzing ChIP-chip datasets across the human genome in three cell types, we have found that this marking system is far more complex than previously observed. We show here that a range of histone modifications and Pol II are preferentially associated with exons. However, there is noticeable cell-type specificity in the degree of exon marking by histone modifications and, surprisingly, this is also reflected in some histone modifications patterns showing biases towards introns. Exon-intron marking is laid down in the absence of transcription on silent genes, with some marking biases changing or becoming reversed for genes expressed at different levels. Furthermore, the relationship of this marking system with splicing is not simple, with only some histone modifications reflecting exon usage/inclusion, while others mirror patterns of exon exclusion. By examining nucleosomal distributions in all three cell types, we demonstrate that these histone modification patterns cannot solely be accounted for by differences in nucleosome levels between exons and introns. In addition, because of inherent differences between ChIP-chip array and ChIP-sequencing approaches, these platforms report different nucleosome distribution patterns across the human genome. Our findings confound existing views and point to active cellular mechanisms which dynamically regulate histone modification levels and account for exon-intron marking. We believe that these histone modification patterns provide links between chromatin accessibility, Pol II movement and co-transcriptional splicing

Status and Recent Results of the Acoustic Neutrino Detection Test System AMADEUS

The AMADEUS system is an integral part of the ANTARES neutrino telescope in the Mediterranean Sea. The project aims at the investigation of techniques for acoustic neutrino detection in the deep sea. Installed at a depth of more than 2000m, the acoustic sensors of AMADEUS are based on piezo-ceramics elements for the broad-band recording of signals with frequencies ranging up to 125kHz. AMADEUS was completed in May 2008 and comprises six "acoustic clusters", each one holding six acoustic sensors that are arranged at distances of roughly 1m from each other. The clusters are installed with inter-spacings ranging from 15m to 340m. Acoustic data are continuously acquired and processed at a computer cluster where online filter algorithms are applied to select a high-purity sample of neutrino-like signals. 1.6 TB of data were recorded in 2008 and 3.2 TB in 2009. In order to assess the background of neutrino-like signals in the deep sea, the characteristics of ambient noise and transient signals have been investigated. In this article, the AMADEUS system will be described and recent results will be presented.Comment: 7 pages, 8 figures. Proceedings of ARENA 2010, the 4th International Workshop on Acoustic and Radio EeV Neutrino Detection Activitie

The ANTARES Telescope Neutrino Alert System

The ANTARES telescope has the capability to detect neutrinos produced in astrophysical transient sources. Potential sources include gamma-ray bursts, core collapse supernovae, and flaring active galactic nuclei. To enhance the sensitivity of ANTARES to such sources, a new detection method based on coincident observations of neutrinos and optical signals has been developed. A fast online muon track reconstruction is used to trigger a network of small automatic optical telescopes. Such alerts are generated for special events, such as two or more neutrinos, coincident in time and direction, or single neutrinos of very high energy.Comment: 17 pages, 9 figures submitted to Astroparticle Physic

Measurement of Atmospheric Neutrino Oscillations with the ANTARES Neutrino Telescope

The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total live time of 863 days, are used to measure the oscillation parameters of atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20 GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon neutrinos of such energies crossing the Earth. The parameters determining the oscillation of atmospheric neutrinos are extracted by fitting the event rate as a function of the ratio of the estimated neutrino energy and reconstructed flight path through the Earth. Measurement contours of the oscillation parameters in a two-flavour approximation are derived. Assuming maximum mixing, a mass difference of $\Delta m_{32}^2=(3.1\pm 0.9)\cdot 10^{-3}$ eV$^2$ is obtained, in good agreement with the world average value.Comment: 9 pages, 5 figure

A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000

The Delphi Delirium Management Algorithms. A practical tool for clinicians, the result of a modified Delphi expert consensus approach

Delirium is common in hospitalised patients, and there is currently no specific treatment. Identifying and treating underlying somatic causes of delirium is the first priority once delirium is diagnosed. Several international guidelines provide clinicians with an evidence-based approach to screening, diagnosis and symptomatic treatment. However, current guidelines do not offer a structured approach to identification of underlying causes. A panel of 37 internationally recognised delirium experts from diverse medical backgrounds worked together in a modified Delphi approach via an online platform. Consensus was reached after five voting rounds. The final product of this project is a set of three delirium management algorithms (the Delirium Delphi Algorithms), one for ward patients, one for patients after cardiac surgery and one for patients in the intensive care unit.</p