Monitoring remote ocean waves using P-wave microseisms

Oceanic microseisms are generated by the interaction of opposing ocean waves and subsequent coupling with the seabed, so microseisms should contain information on the ocean conditions that generated them. This leads to the possibility of using seismic records as a proxy for the ocean gravity wavefield. Here we investigate the P-wave component of microseisms, which has previously been linked to areas of high wave interaction intensity in mid-ocean regions. We compare modeled P-wave microseismic sources with those observed at an array in California, and also investigate the relationship between observed sources and significant wave height. We found that the time-varying location of microseism sources in the North Pacific, mapped from beamforming and backprojection of seismic data, was accurate to ≤10° in 90% of cases. The modeled sources were found to dominate at ∼0.2 Hz which was also reflected in the seismic observations. An empirical relationship between observed beampower and modeled source power allowed sources during an independent data period to be estimated with a correlation coefficient of 0.63. Likewise, significant wave height was also estimated with a correlation coefficient of 0.63. Our findings suggest that with improvements in resolution and amplitude retrieval from beamforming, correlations up to 0.78 should be possible between observed P-wave microseisms and significant wave height in remote ocean regions

Source regions and reflection of infragravity waves offshore of U.S.'s Pacific Northwest

Infragravity waves are oceanic surface gravity waves but with wavelengths (10's km) and periods (>30s) much longer than wind waves and swell. Mostly studied in shallow water, knowledge of infragravity waves in deep water has remained limited. Recent interest in deep-water infragravity waves has been motivated by the error they may contribute to future high-resolution satellite radar altimetry measurements of sea level. Here, deep-water infragravity waves offshore of the Pacific Northwest of the USA were studied using Differential Pressure Gauges which were deployed as part of the Cascadia Initiative array from September 2012-May 2013. Cross-correlation of the records revealed direction of infragravity wave propagation across the array, from which source regions were inferred. The dominant source was found to be the coastline to the east, associated with large wind waves and swell incident on the eastern side of the basin. The source shifted southward during northern-hemisphere summer, and on several days in the record infragravity waves arrived from the western side of the Pacific. Asymmetry of cross-correlation functions for five of these westerly arrivals was used to calculate the ratio of seaward to shoreward propagating energy, and hence estimate the strength of infragravity wave reflection at periods of 100-200s. Reflection of these remote arrivals from the west appeared to be strong, with a lower bound estimate of r=0.49±0.29 (reflection coefficient ± standard error) and an upper bound estimate of r=0.74±0.06. These results suggest that reflection at ocean boundaries may be an important consideration for infragravity waves in the deep ocean

Improving microseismic P wave source location with multiple seismic arrays

Using array analysis, the direction and distance to a seismic P wave source can be determined. However, individual arrays are limited in their geographical coverage and by their resolving capability, which is determined by the array aperture, configuration, and number of stations. We demonstrate these limitations on three large seismic arrays located in Japan, Europe, and California, and find that all give a unique but imperfect insight into the P wave sources acting in the North Pacific. We then combine the data from all three arrays into one beamforming image. The combined images bring together the views offered by each array, providing a concise, comprehensive, and more robust representation of multiple source locations. Next we weight each array for distance in order to optimize the result. Being able to resolve and accurately locate source regions is an important step in being able to use seismic records to monitor ocean wave activity and track storms in real time

Aquilegia Volume 41 No. 5 Fall 2017

https://epublications.regis.edu/aquilegia/1202/thumbnail.jp

Cloning and Sequencing of Protein Kinase cDNA from Harbor Seal (Phoca vitulina) Lymphocytes

Protein kinases (PKs) play critical roles in signal transduction and activation of lymphocytes. The identification of PK genes provides a tool for understanding mechanisms of immunotoxic xenobiotics. As part of a larger study investigating persistent organic pollutants in the harbor seal and their possible immunomodulatory actions, we sequenced harbor seal cDNA fragments encoding PKs. The procedure, using degenerate primers based on conserved motifs of human protein tyrosine kinases (PTKs), successfully amplified nine phocid PK gene fragments with high homology to human and rodent orthologs. We identified eight PTKs and one dual (serine/threonine and tyrosine) kinase. Among these were several PKs important in early signaling events through the B- and T-cell receptors (FYN, LYN, ITK and SYK) and a MAP kinase involved in downstream signal transduction. V-FGR, RET and DDR2 were also expressed. Sequential activation of protein kinases ultimately induces gene transcription leading to the proliferation and differentiation of lymphocytes critical to adaptive immunity. PKs are potential targets of bioactive xenobiotics, including persistent organic pollutants of the marine environment; characterization of these molecules in the harbor seal provides a foundation for further research illuminating mechanisms of action of contaminants speculated to contribute to large-scale die-offs of marine mammals via immunosuppression

PAH- and PCB-induced Alterations of Protein Tyrosine Kinase and Cytokine Gene Transcription in Harbor Seal (Phoca Vitulina) PBMC

Mechanisms underlying in vitro immunomodulatory effects of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were investigated in harbor seal peripheral leukocytes, via real-time PCR. We examined the relative genetic expression of the protein tyrosine kinases (PTKs) Fyn and Itk, which play a critical role in T cell activation, and IL-2, a cytokine of central importance in initiating adaptive immune responses. IL-1, the macrophage-derived pro-inflammatory cytokine of innate immunity, was also included as a measure of macrophage function. Harbor seal PBMC were exposed to the prototypic immunotoxic PAH benzo[a]pyrene (BaP), 3,3',4,4',5,5'-hexachlorobiphenyl (CB-169), a model immunotoxic PCB, or DMSO (vehicle control). Exposure of Con A-stimulated harbor seal PBMC to both BaP and CB-169 produced significantly altered expression in all four targets relative to vehicle controls. The PTKs Fyn and Itk were both up-regulated following exposure to BaP and CB-169. In contrast, transcripts for IL-2 and IL-1 were decreased relative to controls by both treatments. Our findings are consistent with those of previous researchers working with human and rodent systems and support a hypothesis of contaminant-altered lymphocyte function mediated (at least in part) by disruption of T cell receptor (TCR) signaling and cytokine production

Implementation of a Journal Prototype for Pregnant and Parenting Adolescents

Teenage pregnancy and childbearing remain pressing public health issues that have garnered attention from public health officials and social services agencies. This paper reports on the initial implementation and formative evaluation of a journaling program used as a means of communicating health information to pregnant and parenting adolescents (young women age 15-19) while also providing participants with a means of self-expression. The journaling prototype was implemented in a community-based agency in the Midwest by Family Support Specialists (FSSs) who made home visits on a monthly basis to assist pregnant and parenting adolescents (n = 52) with successful family planning and public health education. A mixed method approach of qualitative (analysis of journals, field notes, and responses of semi-structured interviews with FSSs) and quantitative (questionnaires from pregnant and parenting adolescent respondents) data with purposive sampling was employed to evaluate the implementation of the journaling intervention. Twenty of the 52 study participants were pregnant when the journaling intervention was implemented, while 32 were not pregnant, but recently had a child and were currently parenting. Two core themes emerged from analysis of the data after the implementation of the journals: (1) usefulness of the journal and responsiveness to participants' information needs and (2) functionality challenges. The results offer practical starting points to tailor the implementation of journaling in other contexts. Further, areas for improvement emerged regarding the distribution timeline for the journal and the content of the journal itself. As such, we discuss the lessons learned through this collaborative project and suggest opportunities for future phases of the journal intervention