102 research outputs found
Analysis of acoustic propagation in the region of the New England continental shelfbreak
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 1999During July and August of 1996, a large acoustics/physical oceanography experiment
was fielded in the Mid-Atlantic Bight, south of Nantucket Island, MA. Known as
the Shelfbreak Front PRIMER Experiment, the study combined acoustic data from
a moored array of sources and receivers with very high resolution physical oceanographic measurements. This thesis addresses two of the primary goals of the experiment, explaining the properties of acoustic propagation in the region, and tomographic inversion of the acoustic data. In addition, this thesis develops a new method
for predicting acoustic coherence in such regions.
Receptions from two 400 Hz tomography sources, transmitting from the continental slope onto the shelf, are analyzed. This data, along with forward propagation
modeling utilizing SeaSoar thermohaline measurements, reveal that both the shelfbreak
front and tidally-generated soliton packets produce stronger coupling between
the acoustic waveguide modes than expected. Arrival time wander and signal spread
show variability attributable to the presence of a shelf water meander, changes in
frontal configuration, and variability in the soliton field. The highly-coupled nature
of the acoustic mode propagation prevents detailed tomographic inversion. Instead,
methods based on only the wander of the mode arrivals are used to estimate path-averaged
temperatures and internal tide "strength".
The modal phase structure function is introduced as a useful proxy for acoustic
coherence, and is related via an integral transform to the environmental sound speed
correlation function. Advantages of the method are its flexibility and division of the
problem into independent contributions, such as from the water column and seabed.Office of Naval Research for providing funding
for this thesis through AASERT Grant N00014-96-1-0918, and through ONR Grant
N00014-98-1-0059
Modal analysis of vertical array receptions for the Heard Island Feasibility Test
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994.Includes bibliographical references (p. 89-91).by Brian J. Sperry.M.S
Preliminary acoustic and oceanographic observations from the winter Primer experiment
A joint acoustics and physical oceanography experiment was conducted in the winter of 1997 on the shell break and continental
slope south of New England in the Middle Atlantic Bight (figure 1). This experiment, Primer4, provided a seasonal contrast to the
previous summer Primer3 experiment and had the same goals and tasks: to study the thermohaline variability and structure of the
shelfbreak front and its effects on acoustic propagation. To accomplish the linked oceanographic and acoustic objectives of this
experiment, a combination of measurements (fig 2) were made. Seasoar hydrography, shipboard ADCP measurements, Satellite IR
sea surface temperature field observations, and AXT drops were employed to study the larger scale oceanographic fields. To study
the finer scale, which includes internal waves, a number of rapid-sampling thermistor strings and current meters, including a
moored, upward looking ADCP, were deployed. The acoustics components consisted of three 400 Hz tomography transceivers, a
224 Hz source and two hydrophone arrays. To study the geoacoustic parameters in the bottom a number of SUS charges were also
deployed. The field setup was approximately the same for both the summer 1996 and winter 1997 experiments; however the
weather conditions and the thermal structure of the mixed layer were radically different. This report is dedicated to the data from the
Winter 1997 Primer4 experiment.Funding was provided by the Offce of Naval Research under Contract No. NOOOl4-98-10413
Three-dimensional propagation effects near the mid-Atlantic Bight shelf break (L)
Significant three-dimensional (3-D) environmental variability exists in the vicinity of the shelf break along the mid-Atlantic Bight. This study examines the influence of azimuthal coupling due to this variability on acoustic propagation in this region. Numerical studies employing a 3-D ray code, a hybrid ray-mode code, and a 3-D parabolic equation model are used to study the significance of azimuthal coupling on various propagation paths. These paths include up-slope, slant-slope, and cross-slope propagation. The numerical analysis suggests that, for the propagation ranges less than 60 km examined, the influence of azimuthal coupling is negligible compared to the inherent uncertainty in the environment itself
Elevated Admission Base Deficit Is Associated with a Complex Dynamic Network of Systemic Inflammation Which Drives Clinical Trajectories in Blunt Trauma Patients
Multi-omic analysis in injured humans: Patterns align with outcomes and treatment responses
Trauma is a leading cause of death and morbidity worldwide. Here, we present the analysis of a longitudinal multi-omic dataset comprising clinical, cytokine, endotheliopathy biomarker, lipidome, metabolome, and proteome data from severely injured humans. A "systemic storm" pattern with release of 1,061 markers, together with a pattern suggestive of the "massive consumption" of 892 constitutive circulating markers, is identified in the acute phase post-trauma. Data integration reveals two human injury response endotypes, which align with clinical trajectory. Prehospital thawed plasma rescues only endotype 2 patients with traumatic brain injury (30-day mortality: 30.3 versus 75.0%; p = 0.0015). Ubiquitin carboxy-terminal hydrolase L1 (UCHL1) was identified as the most predictive circulating biomarker to identify endotype 2-traumatic brain injury (TBI) patients. These response patterns refine the paradigm for human injury, while the datasets provide a resource for the study of critical illness, trauma, and human stress responses
Mutations in Zebrafish lrp2 Result in Adult-Onset Ocular Pathogenesis That Models Myopia and Other Risk Factors for Glaucoma
The glaucomas comprise a genetically complex group of retinal neuropathies that typically occur late in life and are characterized by progressive pathology of the optic nerve head and degeneration of retinal ganglion cells. In addition to age and family history, other significant risk factors for glaucoma include elevated intraocular pressure (IOP) and myopia. The complexity of glaucoma has made it difficult to model in animals, but also challenging to identify responsible genes. We have used zebrafish to identify a genetically complex, recessive mutant that shows risk factors for glaucoma including adult onset severe myopia, elevated IOP, and progressive retinal ganglion cell pathology. Positional cloning and analysis of a non-complementing allele indicated that non-sense mutations in low density lipoprotein receptor-related protein 2 (lrp2) underlie the mutant phenotype. Lrp2, previously named Megalin, functions as an endocytic receptor for a wide-variety of bioactive molecules including Sonic hedgehog, Bone morphogenic protein 4, retinol-binding protein, vitamin D-binding protein, and apolipoprotein E, among others. Detailed phenotype analyses indicated that as lrp2 mutant fish age, many individuals—but not all—develop high IOP and severe myopia with obviously enlarged eye globes. This results in retinal stretch and prolonged stress to retinal ganglion cells, which ultimately show signs of pathogenesis. Our studies implicate altered Lrp2-mediated homeostasis as important for myopia and other risk factors for glaucoma in humans and establish a new genetic model for further study of phenotypes associated with this disease
SNAPSHOT USA 2019 : a coordinated national camera trap survey of the United States
This article is protected by copyright. All rights reserved.With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the United States. For our first annual survey, we compiled data across all 50 states during a 14-week period (17 August - 24 November of 2019). We sampled wildlife at 1509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian's eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera trap survey of the USA. All of the 2019 survey data are made available herein. We are currently repeating surveys in fall 2020, opening up the opportunity to other institutions and cooperators to expand coverage of all the urban-wild gradients and ecophysiographic regions of the country. Future data will be available as the database is updated at eMammal.si.edu/snapshot-usa, as well as future data paper submissions. These data will be useful for local and macroecological research including the examination of community assembly, effects of environmental and anthropogenic landscape variables, effects of fragmentation and extinction debt dynamics, as well as species-specific population dynamics and conservation action plans. There are no copyright restrictions; please cite this paper when using the data for publication.Publisher PDFPeer reviewe
Reproductive health indicators of fishes from Pennsylvania watersheds: association with chemicals of emerging concern
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