22 research outputs found
Ocean Bottom Seismometer Augmentation in the North Pacific (OBSANP) - cruise report
The Ocean Bottom Seismometer Augmentation in the North Pacific Experiment (OBSANP,
June-July, 2013, R/V Melville) addresses the coherence and depth dependence of deep-water
ambient noise and signals. During the 2004 NPAL Experiment in the North Pacific Ocean, in
addition to predicted ocean acoustic arrivals and deep shadow zone arrivals, we observed "deep
seafloor arrivals" (DSFA) that were dominant on the seafloor Ocean Bottom Seismometer (OBS)
(at about 5000m depth) but were absent or very weak on the Distributed Vertical Line Array
(DVLA) (above 4250m depth). At least a subset of these arrivals correspond to bottomdiffracted
surface-reflected (BDSR) paths from an out-of-plane seamount. BDSR arrivals are
present throughout the water column, but at depths above the conjugate depth are obscured by
ambient noise and PE predicted arrivals. On the 2004 NPAL/LOAPEX experiment BDSR paths
yielded the largest amplitude seafloor arrivals for ranges from 500 to 3200km. The OBSANP
experiment tests the hypothesis that BDSR paths contribute to the arrival structure on the deep
seafloor even at short ranges (from near zero to 4-1/2CZ). The OBSANP cruise had three major
research goals: a) identification and analysis of DSFA and BDSR arrivals occurring at short
(1/2CZ) ranges in the 50 to 400Hz band, b) analysis of deep sea ambient noise in the band 0.03
to 80Hz, and c) analysis of the frequency dependence of BR and SRBR paths. On OBSANP we
deployed a 32 element VLA from 12 to 1000m above the seafloor, eight short-period OBSs and
four long-period OBSs and carried out a 15day transmission program using a J15-3 acoustic
source.Funding was provided by the Office of Naval Research under contract #'s N00014-10-1-0987
and N00014-10-1-051
Ocean Bottom Seismometer Augmentation of the Philippine Sea Experiment (OBSAPS) cruise report
The Ocean Bottom Seismometer Augmentation to the Philippine Sea Experiment
(OBSAPS, April-May, 2011, R/V Revelle) addresses the coherence and depth dependence of
deep-water ambient noise and signals. During the 2004 NPAL Experiment in the North Pacific
Ocean, in addition to predicted ocean acoustic arrivals and deep shadow zone arrivals, we
observed "deep seafloor arrivals" that were dominant on the seafloor Ocean Bottom Seismometer
(OBS) (at about 5000m depth) but were absent or very weak on the Distributed Vertical Line
Array (DVLA) (above 4250m depth). These "deep seafloor arrivals" (DSFA) are a new class of
arrivals in ocean acoustics possibly associated with seafloor interface waves. The OBSAPS
cruise had three major research goals: a) identification and analysis of DSFAs occurring at short
(1/2CZ) ranges in the 50 to 400Hz band, b) analysis of deep sea ambient noise in the band 0.03
to 80Hz, and c) analysis of the frequency dependence of BR and SRBR paths as a function of
frequency. On OBSAPS we deployed a fifteen element VLA from 12 to 852m above the
seafloor, four short-period OBSs and two long-period OBSs and carried out an 11.5day
transmission program using a J15-3 acoustic source.Funding was provided by the Office of Naval Research under Contract Nos. N00014-10-1-0994
and N00014-10-1-0987
ALBACORE OBS recovery cruise report
The primary goal of the 2011 ALBACORE (Asthenosphere and
Lithosphere Broadband Architecture from the California
Offshore Region Experiment) cruise was to recover 34 ocean bottom seismometers (OBSs) in a 150 km (north-south) by 400 km (east-west) region off the coast of Southern California (Fig. 1). The cruise took place on R/V New Horizon, departing out of San Diego on Sept 7, 2011 and arriving back in San Diego on Sept 16, 2011 with no port stops in between
ALBACORE OBS deployment cruise report
The primary goal of the 2010 ALBACORE (Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment) cruise was to deploy 34 ocean bottom seismometers (OBSs) in a 150 km (north-south) by 400 km (east-west) region off the coast of Southern California (Fig. 1). The cruise took place on R/V Melville, departing out of San Diego on August 14, 2010 and arriving back in San Diego on August 27, 2001 with no port stops in between
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure