588 research outputs found
Enrichment of microbial populations in macroaggregates (marine snow) from surface waters of the North Atlantic
Marine snow particles (macroscopic detrital aggregates) were collected from surface waters throughout the western North Atlantic. Counts of phototrophic and heterotrophic picoplankton, phototrophic and heterotrophic nanoplankton, and phototrophic microplankton were made by epifluorescence microscopy. A Most Probable Number culture technique also was used to estimate the density of bacterivorous protozoa. All microbial populations enumerated were highly enriched on macroaggregates relative to their densities in the surrounding water. The degree of enrichment was greater in open ocean environments because microorganisms in the surrounding water were less abundant in the open ocean than in nearshore waters, and also because microbial density on marine snow was greater in the open ocean than in nearshore environments. Material released by ctenophores and appendicularia is a likely source of marine snow since it supported microbial populations of the same order of magnitude as were observed on SCUBA-collected particles. Heterotrophic nanoflagellates dominated the bacterivorous protozoa cultured from macroaggregates and the surrounding water, but dense populations of ciliates and amoebae also were present on particles. Protozoan populations on marine snow were so dense relative to the surrounding water as to suggest that detrital aggregates are responsible for the planktonic existence of some bacterivorous species
Observational Limit on Gravitational Waves from Binary Neutron Stars in the Galaxy
Using optimal matched filtering, we search 25 hours of data from the LIGO
40-meter prototype laser interferometric gravitational-wave detector for
gravitational-wave chirps emitted by coalescing binary systems within our
Galaxy. This is the first test of this filtering technique on real
interferometric data. An upper limit on the rate R of neutron star binary
inspirals in our Galaxy is obtained: with 90% confidence, R< 0.5/hour. Similar
experiments with LIGO interferometers will provide constraints on the
population of tight binary neutron star systems in the Universe.Comment: RevTeX, minor revisions, exactly as published in PRL 83 (1999) p1498,
4 pages, 2 figures include
Thrombolytic removal of intraventricular haemorrhage in treatment of severe stroke: results of the randomised, multicentre, multiregion, placebo-controlled CLEAR III trial
Background:
Intraventricular haemorrhage is a subtype of intracerebral haemorrhage, with 50% mortality and serious disability for survivors. We aimed to test whether attempting to remove intraventricular haemorrhage with alteplase versus saline irrigation improved functional outcome.
Methods:
In this randomised, double-blinded, placebo-controlled, multiregional trial (CLEAR III), participants with a routinely placed extraventricular drain, in the intensive care unit with stable, non-traumatic intracerebral haemorrhage volume less than 30 mL, intraventricular haemorrhage obstructing the 3rd or 4th ventricles, and no underlying pathology were adaptively randomly assigned (1:1), via a web-based system to receive up to 12 doses, 8 h apart of 1 mg of alteplase or 0·9% saline via the extraventricular drain. The treating physician, clinical research staff, and participants were masked to treatment assignment. CT scans were obtained every 24 h throughout dosing. The primary efficacy outcome was good functional outcome, defined as a modified Rankin Scale score (mRS) of 3 or less at 180 days per central adjudication by blinded evaluators. This study is registered with ClinicalTrials.gov, NCT00784134.
Findings:
Between Sept 18, 2009, and Jan 13, 2015, 500 patients were randomised: 249 to the alteplase group and 251 to the saline group. 180-day follow-up data were available for analysis from 246 of 249 participants in the alteplase group and 245 of 251 participants in the placebo group. The primary efficacy outcome was similar in each group (good outcome in alteplase group 48% vs saline 45%; risk ratio [RR] 1·06 [95% CI 0·88–1·28; p=0·554]). A difference of 3·5% (RR 1·08 [95% CI 0·90–1·29], p=0·420) was found after adjustment for intraventricular haemorrhage size and thalamic intracerebral haemorrhage. At 180 days, the treatment group had lower case fatality (46 [18%] vs saline 73 [29%], hazard ratio 0·60 [95% CI 0·41–0·86], p=0·006), but a greater proportion with mRS 5 (42 [17%] vs 21 [9%]; RR 1·99 [95% CI 1·22–3·26], p=0·007). Ventriculitis (17 [7%] alteplase vs 31 [12%] saline; RR 0·55 [95% CI 0·31–0·97], p=0·048) and serious adverse events (114 [46%] alteplase vs 151 [60%] saline; RR 0·76 [95% CI 0·64–0·90], p=0·002) were less frequent with alteplase treatment. Symptomatic bleeding (six [2%] in the alteplase group vs five [2%] in the saline group; RR 1·21 [95% CI 0·37–3·91], p=0·771) was similar.
Interpretation:
In patients with intraventricular haemorrhage and a routine extraventricular drain, irrigation with alteplase did not substantially improve functional outcomes at the mRS 3 cutoff compared with irrigation with saline. Protocol-based use of alteplase with extraventricular drain seems safe. Future investigation is needed to determine whether a greater frequency of complete intraventricular haemorrhage removal via alteplase produces gains in functional status
Diversity and toxicity of Pseudo-nitzschia species in Monterey Bay : perspectives from targeted and adaptive sampling
Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Harmful Algae 78 (2018): 129-141, doi:10.1016/j.hal.2018.08.006.Monterey Bay, California experiences near-annual blooms of Pseudo-nitzschia that can
affect marine animal health and the economy, including impacts to tourism and
commercial/recreational fisheries. One species in particular, P. australis, has been
implicated in the most toxic of events, however other species within the genus can
contribute to widespread variability in community structure and associated toxicity across
years. Current monitoring methods are limited in their spatial coverage as well as their
ability to capture the full suite of species present, thereby hindering understanding of
HAB events and limiting predictive accuracy. An integrated deployment of multiple in
situ platforms, some with autonomous adaptive sampling capabilities, occurred during
two divergent bloom years in the bay, and uncovered detailed aspects of population and
toxicity dynamics. A bloom in 2013 was characterized by spatial differences in Pseudo39
nitzschia populations, with the low-toxin producer P. fraudulenta dominating the inshore
community and toxic P. australis dominating the offshore community. An exceptionally
toxic bloom in 2015 developed as a diverse Pseudo-nitzschia community abruptly
transitioned into a bloom of highly toxic P. australis within the time frame of a week.
Increases in cell density and proliferation coincided with strong upwelling of nutrients.
High toxicity was driven by silicate limitation of the dense bloom. This temporal shift in
species composition mirrored the shift observed further north in the California Current
System off Oregon and Washington. The broad scope of sampling and unique platform
capabilities employed during these studies revealed important patterns in bloom
formation and persistence for Pseudo-nitzschia. Results underscore the benefit of
expanded biological observing capabilities and targeted sampling methods to capture
more comprehensive spatial and temporal scales for studying and predicting future
events.This work was
supported by the National Oceanic and Atmospheric Administration
(NA11NOS4780055, NA11NOS4780056, NA11NOS4780030) and a fellowship to H.
Bowers from the Packard Foundation
Characterization of Antibodies against Receptor Activity-Modifying Protein 1 (RAMP1): A Cautionary Tale
Calcitonin gene-related peptide (CGRP) is a key component of migraine pathophysiology, yielding effective migraine therapeutics. CGRP receptors contain a core accessory protein subunit: receptor activity-modifying protein 1 (RAMP1). Understanding of RAMP1 expression is incomplete, partly due to the challenges in identifying specific and validated antibody tools. We profiled antibodies for immunodetection of RAMP1 using Western blotting, immunocytochemistry and immunohistochemistry, including using RAMP1 knockout mouse tissue. Most antibodies could detect RAMP1 in Western blotting and immunocytochemistry using transfected cells. Two antibodies (844, ab256575) could detect a RAMP1-like band in Western blots of rodent brain but not RAMP1 knockout mice. However, cross-reactivity with other proteins was evident for all antibodies. This cross-reactivity prevented clear conclusions about RAMP1 anatomical localization, as each antibody detected a distinct pattern of immunoreactivity in rodent brain. We cannot confidently attribute immunoreactivity produced by RAMP1 antibodies (including 844) to the presence of RAMP1 protein in immunohistochemical applications in brain tissue. RAMP1 expression in brain and other tissues therefore needs to be revisited using RAMP1 antibodies that have been comprehensively validated using multiple strategies to establish multiple lines of convincing evidence. As RAMP1 is important for other GPCR/ligand pairings, our results have broader significance beyond the CGRP field
Generic multiloop methods and application to N=4 super-Yang-Mills
We review some recent additions to the tool-chest of techniques for finding
compact integrand representations of multiloop gauge-theory amplitudes -
including non-planar contributions - applicable for N=4 super-Yang-Mills in
four and higher dimensions, as well as for theories with less supersymmetry. We
discuss a general organization of amplitudes in terms of purely cubic graphs,
review the method of maximal cuts, as well as some special D-dimensional
recursive cuts, and conclude by describing the efficient organization of
amplitudes resulting from the conjectured duality between color and kinematic
structures on constituent graphs.Comment: 42 pages, 18 figures, invited review for a special issue of Journal
of Physics A devoted to "Scattering Amplitudes in Gauge Theories", v2 minor
corrections, v3 added reference
Search for the Standard Model Higgs Boson with the OPAL Detector at LEP
This paper summarises the search for the Standard Model Higgs boson in e+e-
collisions at centre-of-mass energies up to 209 GeV performed by the OPAL
Collaboration at LEP. The consistency of the data with the background
hypothesis and various Higgs boson mass hypotheses is examined. No indication
of a signal is found in the data and a lower bound of 112.7GeV/C^2 is obtained
on the mass of the Standard Model Higgs boson at the 95% CL.Comment: 51 pages, 21 figure
Measurement of the Hadronic Photon Structure Function F_2^gamma at LEP2
The hadronic structure function of the photon F_2^gamma is measured as a
function of Bjorken x and of the factorisation scale Q^2 using data taken by
the OPAL detector at LEP. Previous OPAL measurements of the x dependence of
F_2^gamma are extended to an average Q^2 of 767 GeV^2. The Q^2 evolution of
F_2^gamma is studied for average Q^2 between 11.9 and 1051 GeV^2. As predicted
by QCD, the data show positive scaling violations in F_2^gamma. Several
parameterisations of F_2^gamma are in agreement with the measurements whereas
the quark-parton model prediction fails to describe the data.Comment: 4 pages, 2 figures, to appear in the proceedings of Photon 2001,
Ascona, Switzerlan
Search for R-Parity Violating Decays of Scalar Fermions at LEP
A search for pair-produced scalar fermions under the assumption that R-parity
is not conserved has been performed using data collected with the OPAL detector
at LEP. The data samples analysed correspond to an integrated luminosity of
about 610 pb-1 collected at centre-of-mass energies of sqrt(s) 189-209 GeV. An
important consequence of R-parity violation is that the lightest supersymmetric
particle is expected to be unstable. Searches of R-parity violating decays of
charged sleptons, sneutrinos and squarks have been performed under the
assumptions that the lightest supersymmetric particle decays promptly and that
only one of the R-parity violating couplings is dominant for each of the decay
modes considered. Such processes would yield final states consisting of
leptons, jets, or both with or without missing energy. No significant
single-like excess of events has been observed with respect to the Standard
Model expectations. Limits on the production cross- section of scalar fermions
in R-parity violating scenarios are obtained. Constraints on the supersymmetric
particle masses are also presented in an R-parity violating framework analogous
to the Constrained Minimal Supersymmetric Standard Model.Comment: 51 pages, 24 figures, Submitted to Eur. Phys. J.
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