345 research outputs found
Larval culture of the calico scallop, Argopecten gibbus
Mature calico scallops, Argopecten gibbus, collected from the grounds off Cape Kennedy, Florida, were induced to spawn in the laboratory. Fertilized eggs were reared to postlarvae in sea water of 23° C ± 2.0° C at a salinity of 35 %o. The external morphology of eggs and developing larval stages are described
Evolution of foreland basin fluvial systems in the mid-Cretaceous of Utah, USA (upper Cedar Mountain and Naturita formations)
ACKNOWLEDGEMENTS This work was funded by the SAFARI group. We are deeply grateful to Joe Phillips, Sean Kelly, James Mullins, Ryan King and Jostein Myking Kjærefjord for help in the field. We would also like to thank Associate Editor, Christopher Fielding, for handling the review of this paper. Additionally we thank reviewers Benjamin Cardenas and Brian Currie for their comments and suggested revisions which have greatly enhanced this paper. Open Access via the Jisc Wiley AgreementPeer reviewedPublisher PD
Array processing in cryoseismology: a comparison to network-based approaches at an Antarctic ice stream
Seismicity at glaciers, ice sheets, and ice shelves
provides observational constraint on a number of glaciologi-
cal processes. Detecting and locating this seismicity, specifi-
cally icequakes, is a necessary first step in studying processes
such as basal slip, crevassing, imaging ice fabric, and iceberg
calving, for example. Most glacier deployments to date use
conventional seismic networks, comprised of seismometers
distributed over the entire area of interest. However, smaller-
aperture seismic arrays can also be used, which are typically
sensitive to seismicity distal from the array footprint and re-
quire a smaller number of instruments. Here, we investigate
the potential of arrays and array-processing methods to de-
tect and locate subsurface microseismicity at glaciers, bench-
marking performance against conventional seismic-network-
based methods for an example at an Antarctic ice stream.
We also provide an array-processing recipe for body-wave
cryoseismology applications. Results from an array and a
network deployed at Rutford Ice Stream, Antarctica, show
that arrays and networks both have strengths and weaknesses.
Arrays can detect icequakes from further distances, whereas
networks outperform arrays in more comprehensive studies
of a particular process due to greater hypocentral constraint
within the network extent. We also gain new insights into
seismic behaviour at the Rutford Ice Stream. The array de-
tects basal icequakes in what was previously interpreted to
be an aseismic region of the bed, as well as new icequake
observations downstream and at the ice stream shear mar-
gins, where it would be challenging to deploy instruments.
Finally, we make some practical recommendations for future
array deployments at glaciers
UNIONS: The impact of systematic errors on weak-lensing peak counts
UNIONS is an ongoing deep photometric multi-band survey of the Northern sky.
As part of UNIONS, CFIS provides r-band data which we use to study weak-lensing
peak counts for cosmological inference. We assess systematic effects for
weak-lensing peak counts and their impact on cosmological parameters for the
UNIONS survey. In particular, we present results on local calibration,
metacalibration shear bias, baryonic feedback, the source galaxy redshift
estimate, intrinsic alignment, and the cluster member dilution. For each
uncertainty and systematic effect, we describe our mitigation scheme and the
impact on cosmological parameter constraints. We obtain constraints on
cosmological parameters from MCMC using CFIS data and MassiveNuS N-body
simulations as a model for peak counts statistics. Depending on the calibration
(local versus global, and the inclusion of the residual multiplicative shear
bias), the mean matter density parameter can shift up to
(). We also see that including baryonic corrections can shift
by () with respect to the DM-only simulations.
Reducing the impact of the intrinsic alignment and cluster member dilution
through signal-to-noise cuts can lead to a shift in of
(). Finally, with a mean redshift uncertainty of , we see that the shift of ( which corresponds to
) is not significant. This paper investigates for the first time
with UNIONS weak-lensing data and peak counts the impact of systematic effects.
The value of is the most impacted and can shift up to
which corresponds to depending on the choices for each systematics.
We expect constraints to become more reliable with future (larger) data
catalogues, for which the current pipeline will provide a starting point.Comment: 17 pages, 17 figure
Errors in stimulated-Raman-induced logic gates in Ba
is illuminated by a laser that is far-detuned from
optical transitions, and the resulting spontaneous Raman scattering rate is
measured. The observed scattering rate is lower than previous theoretical
estimates. The majority of the discrepancy is explained by a more accurate
treatment of the scattered photon density of states. This work establishes
that, contrary to previous models, there is no fundamental limit to
laser-driven quantum gates from laser-induced spontaneous Raman scattering.Comment: 4 + 2 pages, 4 + 1 figure
Graphene Oxide Reduces the Hydrolytic Degradation in Polyamide-11
Graphene oxide (GO) was incorporated into polyamide-11 (PA11) via in-situ polymerization. The GO-PA11 nano-composite had elevated resistance to hydrolytic degradation. At a loading of 1 mg/g, GO to PA11, the accelerated aging equilibrium molecular weight of GO-PA11 was higher (33 and 34 kg/mol at 100 and 120 C, respectively) compared to neat PA11 (23 and 24 kg/mol at 100 and 120 C, respectively). Neat PA11 had hydrolysis rate constants (kH) of 2.8 and 12 ( 10(exp -2) day(exp -1)) when aged at 100 and 120 C, respectively, and re-polymerization rate constants (kP) of 5.0 and 23 ( 10(exp -5) day(exp -1)), respectively. The higher equilibrium molecular weight for GO-PA11 loaded at 1 mg/g was the result of a decreased kH, 1.8 and 4.5 ( 10(exp -2) day(exp -1)), and an increased kP, 10 and 17 ( 10(exp -5) day(exp -1)) compared with neat PA11 at 100 and 120 C, respectively. The decreased rate of degradation and resulting 40% increased equilibrium molecular weight of GO-PA11 was attributed to the highly asymmetric planar GO nano-sheets that inhibited the molecular mobility of water and the polymer chain. The crystallinity of the polymer matrix was similarly affected by a reduction in chain mobility during annealing due to the GO nanoparticles' chemistry and highly asymmetric nano-planar sheet structure
Array processing in cryoseismology
Seismicity at glaciers, ice sheets, and ice shelves provides observational constraint on a number of glaciological processes. Detecting and locating this seismicity, specifically icequakes, is a necessary first step in studying processes such as basal slip, crevassing, imaging ice fabric, and iceberg calving, for example. Most glacier deployments to date use conventional seismic networks, comprised of seismometers distributed over the entire area of interest. However, smaller-aperture seismic arrays can also be used, which are typically sensitive to seismicity distal from the array footprint and require a smaller number of instruments. Here, we investigate the potential of arrays and array-processing methods to detect and locate subsurface microseismicity at glaciers, benchmarking performance against conventional seismic-network-based methods for an example at an Antarctic ice stream. We also provide an array-processing recipe for body-wave cryoseismology applications. Results from an array and a network deployed at Rutford Ice Stream, Antarctica, show that arrays and networks both have strengths and weaknesses. Arrays can detect icequakes from further distances, whereas networks outperform arrays in more comprehensive studies of a particular process due to greater hypocentral constraint within the network extent. We also gain new insights into seismic behaviour at the Rutford Ice Stream. The array detects basal icequakes in what was previously interpreted to be an aseismic region of the bed, as well as new icequake observations downstream and at the ice stream shear margins, where it would be challenging to deploy instruments. Finally, we make some practical recommendations for future array deployments at glaciers
Black-Hole-to-Halo Mass Relation From UNIONS Weak Lensing
This letter presents, for the first time, direct constraints on the
black-hole-to-halo-mass relation using weak gravitational lensing measurements.
We construct type I and type II Active Galactic Nuclei (AGNs) samples from the
Sloan Digital Sky Survey (SDSS), with a mean redshift of 0.4 0.1 for type I
(type II) AGNs. This sample is cross-correlated with weak lensing shear from
the Ultraviolet Near Infrared Northern Survey (UNIONS). We compute the excess
surface mass density of the halos associated with AGNs from
lensed galaxies and fit the halo mass in bins of black-hole mass.
We find that more massive AGNs reside in more massive halos. We see no evidence
of dependence on AGN type or redshift in the black-hole-to-halo-mass
relationship when systematic errors in the measured black-hole masses are
included. Our results are consistent with previous measurements for non-AGN
galaxies. At a fixed black-hole mass, our weak-lensing halo masses are
consistent with galaxy rotation curves, but significantly lower than galaxy
clustering measurements. Finally, our results are broadly consistent with
state-of-the-art hydro-dynamical cosmological simulations, providing a new
constraint for black-hole masses in simulations.Comment: 14 pages, 5 figures. Submitted to ApJ
The SAMI Galaxy Survey: Quenching of Star Formation in Clusters I. Transition Galaxies
We use integral-field spectroscopy from the SAMI Galaxy Survey to identify galaxies that show evidence of recent quenching of star formation. The galaxies exhibit strong Balmer absorption in the absence of ongoing star formation in more than 10% of their spectra within the SAMI field of view. These Hd-strong (HDS) galaxies (HDSGs) are rare, making up only similar to 2% (25/1220) of galaxies with stellar mass log(M-*/M-circle dot) > 10. The HDSGs make up a significant fraction of nonpassive cluster galaxies (15%; 17/115) and a smaller fraction (2.0%; 8/387) of the nonpassive population in low-density environments. The majority (9/17) of cluster HDSGs show evidence of star formation at their centers, with the HDS regions found in the outer parts of the galaxy. Conversely, the HDS signal is more evenly spread across the galaxy for the majority (6/8) of HDSGs in low-density environments and is often associated with emission lines that are not due to star formation. We investigate the location of the HDSGs in the clusters, finding that they are exclusively within 0.6R(200) of the cluster center and have a significantly higher velocity dispersion relative to the cluster population. Comparing their distribution in projected phase space to those derived from cosmological simulations indicates that the cluster HDSGs are consistent with an infalling population that has entered the central 0.5r(200,3D) cluster region within the last similar to 1 Gyr. In the eight of nine cluster HDSGs with central star formation, the extent of star formation is consistent with that expected of outside-in quenching by ram pressure stripping. Our results indicate that the cluster HDSGs are currently being quenched by ram pressure stripping on their first passage through the cluster
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