106 research outputs found
Crustal structure across the Grand Banks–Newfoundland Basin Continental Margin – II. Results from a seismic reflection profile
Author Posting. © Blackwell, 2006. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 167 (2006): 157-170, doi:10.1111/j.1365-246X.2006.02989.x.New multi-channel seismic (MCS) reflection data were collected over a 565km
transect covering the non-volcanic rifted margin of the central eastern Grand Banks and the Newfoundland Basin in the northwestern Atlantic. Three major crustal zones are interpreted from west to east over the seaward 350-km of the profile: (1) continental crust; (2) transitional basement; (3) oceanic crust. Continental crust thins over a wide zone (~160 km) by forming a large rift basin (Carson Basin) and seaward fault block, together with a series of smaller fault blocks eastward beneath the Salar and Newfoundland basins. Analysis of selected previous reflection profiles (Lithoprobe 85-4, 85-2 and Conrad NB-1) indicates that prominent landward-dipping reflections observed under the continental slope are a regional phenomenon. They define the landward edge of a deep serpentinized mantle layer, which underlies both extended continental crust and transitional basement. The 80-km-wide transitional basement is defined landward by a basement high that may consist of serpentinized peridotite and seaward by a pair of basement highs of unknown crustal origin.
Flat and unreflective transitional basement most likely is exhumed, serpentinized mantle,
although our results do not exclude the possibility of anomalously thinned oceanic crust. A Moho reflection below interpreted oceanic crust is first observed landward of magnetic
anomaly M4, 230 km from the shelf break. Extrapolation of ages from chron M0 to the edge of interpreted oceanic crust suggests that the onset of seafloor spreading was ~138Ma (Valanginian) in the south (southern Newfoundland Basin) to ~125Ma (Barremian-Aptian boundary) in the north (Flemish Cap), comparable to those proposed for the conjugate margins.This work was funded by NSF grants OCE-9819053 and OCE-0326714 to
Woods Hole Oceanographic Institution, NSERC (Canada) and the Danish Research Council.
B. Tucholke also acknowledges support from the Henry Bryant Bigelow Chair in
Oceanography at Woods Hole Oceanographic Institution
Crustal structure across the Grand Banks–Newfoundland Basin Continental Margin – I. Results from a seismic refraction profile
Author Posting. © Blackwell, 2006. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Geophysical Journal International 167 (2006): 127-156, doi:10.1111/j.1365-246X.2006.02988.x.A P-wave velocity model along a 565-km-long profile across the Grand
Banks/Newfoundland basin rifted margin is presented. Continental crust ~36-kmthick
beneath the Grand Banks is divided into upper (5.8-6.25 km/s), middle (6.3-
6.53 km/s) and lower crust (6.77-6.9 km/s), consistent with velocity structure of
Avalon zone Appalachian crust. Syn-rift sediment sequences 6-7-km thick occur in
two primary layers within the Jeanne d’Arc and the Carson basins (~3 km/s in upper
layer; ~5 km/s in lower layer). Abrupt crustal thinning (Moho dip ~ 35º) beneath the
Carson basin and more gradual thinning seaward forms a 170-km-wide zone of rifted
continental crust. Within this zone, lower and middle continental crust thin
preferentially seaward until they are completely removed, while very thin (<3 km)
upper crust continues ~60 km farther seaward. Adjacent to the continental crust, high
velocity gradients (0.5-1.5 s-1) define an 80-km-wide zone of transitional basement
that can be interpreted as exhumed, serpentinized mantle or anomalously thin
oceanic crust, based on its velocity model alone. We prefer the exhumed-mantle
interpretation after considering the non-reflective character of the basement and the
low amplitude of associated magnetic anomalies, which are atypical of oceanic crust.
Beneath both the transitional basement and thin (<6 km) continental crust, a 200-kmwide
zone with reduced mantle velocities (7.6-7.9 km/s) is observed, which is
interpreted as partially (<10%) serpentinized mantle. Seaward of the transitional
basement, 2- to 6-km-thick crust with layer 2 (4.5-6.3 km/s) and layer 3 (6.3-7.2
km/s) velocities is interpreted as oceanic crust. Comparison of our crustal model
with profile IAM-9 across the Iberia Abyssal Plain on the conjugate Iberia margin
suggests asymmetrical continental breakup in which a wider zone of extended
continental crust has been left on the Newfoundland side.This research was supported by National Science Foundation (NSF)
grants OCE-9819053 and OCE-0326714, by the National Sciences and Engineering
Research Council of Canada (NSERC), and by the Danish National Research
Foundation. B. Tucholke also acknowledges support from the Henry Bryant Bigelow
Chair in Oceanography from Woods Hole Oceanographic Institution
Standardization of cytokine flow cytometry assays
BACKGROUND: Cytokine flow cytometry (CFC) or intracellular cytokine staining (ICS) can quantitate antigen-specific T cell responses in settings such as experimental vaccination. Standardization of ICS among laboratories performing vaccine studies would provide a common platform by which to compare the immunogenicity of different vaccine candidates across multiple international organizations conducting clinical trials. As such, a study was carried out among several laboratories involved in HIV clinical trials, to define the inter-lab precision of ICS using various sample types, and using a common protocol for each experiment (see additional files online). RESULTS: Three sample types (activated, fixed, and frozen whole blood; fresh whole blood; and cryopreserved PBMC) were shipped to various sites, where ICS assays using cytomegalovirus (CMV) pp65 peptide mix or control antigens were performed in parallel in 96-well plates. For one experiment, antigens and antibody cocktails were lyophilised into 96-well plates to simplify and standardize the assay setup. Results (CD4(+)cytokine(+ )cells and CD8(+)cytokine(+ )cells) were determined by each site. Raw data were also sent to a central site for batch analysis with a dynamic gating template. Mean inter-laboratory coefficient of variation (C.V.) ranged from 17–44% depending upon the sample type and analysis method. Cryopreserved peripheral blood mononuclear cells (PBMC) yielded lower inter-lab C.V.'s than whole blood. Centralized analysis (using a dynamic gating template) reduced the inter-lab C.V. by 5–20%, depending upon the experiment. The inter-lab C.V. was lowest (18–24%) for samples with a mean of >0.5% IFNγ + T cells, and highest (57–82%) for samples with a mean of <0.1% IFNγ + cells. CONCLUSION: ICS assays can be performed by multiple laboratories using a common protocol with good inter-laboratory precision, which improves as the frequency of responding cells increases. Cryopreserved PBMC may yield slightly more consistent results than shipped whole blood. Analysis, particularly gating, is a significant source of variability, and can be reduced by centralized analysis and/or use of a standardized dynamic gating template. Use of pre-aliquoted lyophilized reagents for stimulation and staining can provide further standardization to these assays
Changing portrayals of medicine and patients in eighteenth-century medical writing : Lexical bundles in Public Health, Methods, and case studies
Peer reviewe
Scientific Periodicals : The Philosophical Transactions and the Edinburgh Medical Journal
Peer reviewe
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