Low-frequency surface impedance measurements at some glacial areas in the United States

Radio Science ◽  
1980 ◽  
Vol 15 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Steven A. Arcone ◽  
Allan J. Delaney
Keyword(s):  
United States ◽  
Surface Impedance ◽  
Low Frequency ◽  
The United States ◽  
Impedance Measurements

scholarly journals Diversity of and Selection Acting on CylindrospermopsincyrBGene Adenylation Domain Sequences in Florida

2011 ◽  
Vol 77 (7) ◽  
pp. 2502-2507 ◽  
Author(s):  
Mete Yilmaz ◽  
Edward J. Phlips
Keyword(s):  
United States ◽  
Low Frequency ◽  
Purifying Selection ◽  
The United States ◽  
The Other ◽  
Cylindrospermopsis Raciborskii ◽  
Adenylation Domain ◽  
Other Hand ◽  
Neutrality Tests ◽  
The One

ABSTRACTAphanizomenon ovalisporumis the only confirmed cylindrospermopsin producer identified in the United States to date. On the other hand,Cylindrospermopsis raciborskiiis a prominent feature of many lakes in Florida and other regions of the United States. To see the variation in cylindrospermopsincyrBgene adenylation domain sequences and possibly discover new cylindrospermopsin producers, we collected water samples for a 3-year period from 17 different systems in Florida. Positive amplicons were cloned and sequenced, revealing that approximately 92% of sequences wereA. ovalisporum-like (>99% identity). Interestingly, 6% of sequences were very similar (>99% identity) tocyrBsequences ofC. raciborskiifrom Australia and ofAphanizomenonsp. from Germany. Neutrality tests suggest thatA. ovalisporum-likecyrBadenylation domain sequences are under purifying selection, with abundant low-frequency polymorphisms within the population. On the other hand, when compared between species by codon-based methods, amino acids of CyrB also seem to be under purifying selection, in accordance with the one proposed amino acid thought to be activated by the CyrB adenylation domain.

scholarly journals VLF surface-impedance measurements for ice-depth mapping — an assessment of some commonly encountered interference effects

1996 ◽  
Vol 42 (140) ◽  
pp. 33-36 ◽  
Author(s):  
David V. Thiel ◽  
Daniel James ◽  
Peter Johnson
Keyword(s):  
Surface Impedance ◽  
Apparent Resistivity ◽  
Low Frequency ◽  
Two Dimensional ◽  
Interference Effects ◽  
Impedance Measurements ◽  
Very Low Frequency ◽  
Dimensional Boundary ◽  
Lateral Variations ◽  
Made In

AbstractThe effects on very low-frequency surface-impedence measurements of lateral variations commonly found in ice environments have been measured and modelled numerically using die quasi-static two-dimensional boundary-element method. Results indicate that surface-impedance measurements made in the vicinity of crevasses oriented perpendicular to the plane Of incidence, and those made in the vicinity of moraines and melt streams, can all show significant changes to the measured apparent resistivity. It is, therefore, misleading to use such measurements in the interpretation of ice depth.

scholarly journals Metastatic Pleomorphic Sarcoma to Left Atrium

Rare Tumors ◽  
2009 ◽  
Vol 1 (1) ◽  
pp. 1-3 ◽  
Author(s):  
Ammar H. Hawasli ◽  
Rachael Cayce ◽  
Trung Luong ◽  
Evelyn Taiwo ◽  
Michael N. Feliciano ◽  
...  
Keyword(s):  
United States ◽  
Case Report ◽  
Left Atrium ◽  
Cancer Patients ◽  
Metastatic Disease ◽  
Low Frequency ◽  
The United States ◽  
Cardiovascular Complications ◽  
Pleomorphic Sarcoma

Although several thousand patients are diagnosed with sarcoma annually in the United States, metastases to the heart are very uncommon. In this case report, an overall low frequency cancer presents masquerading with common cardiac symptomology. This case illustrates the importance for detailed diagnostic cardiac evaluations and heightened suspicion by physicians to consider metastatic disease to the heart in cancer patients with cardiovascular complications. Also discussed is a review of surgical and chemotherapeutic options for this problem.

Anomalous Temperature Regimes during the Cool Season: Long-Term Trends, Low-Frequency Mode Modulation, and Representation in CMIP5 Simulations

2013 ◽  
Vol 26 (22) ◽  
pp. 9061-9076 ◽  
Author(s):  
Rebecca M. Westby ◽  
Yun-Young Lee ◽  
Robert X. Black
Keyword(s):  
United States ◽  
Linear Regression Analysis ◽  
Low Frequency ◽  
The United States ◽  
Cmip5 Models ◽  
Southern United States ◽  
Anomalous Temperature ◽  
Temperature Regimes ◽  
Collective Influence

Abstract During boreal winter, anomalous temperature regimes (ATRs), including cold air outbreaks (CAOs) and warm waves (WWs), provide important societal influences upon the United States. The current study analyzes reanalysis and model data for the period from 1949 to 2011 to assess (i) long-term variability in ATRs, (ii) interannual modulation of ATRs by low-frequency modes, and (iii) the representation of ATR behavior in models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). No significant trends in either WWs or CAOs are identified for the continental United States. On interannual time scales, CAOs are modulated by the (i) North Atlantic Oscillation (NAO) over the U.S. Southeast and (ii) the Pacific–North American (PNA) pattern over the Northwest. WW frequency is modulated by (i) the NAO over the eastern United States and (ii) the combined influence of the PNA, Pacific decadal oscillation (PDO), and ENSO over the southern United States. In contrast to previous studies of seasonal-mean temperature, the influence of ENSO upon ATRs is found to be mainly limited to a modest modulation of WWs over the southern United States. Multiple linear regression analysis reveals that the regional collective influence of low-frequency modes accounts for as much as 50% of interannual ATR variability. Although similar behavior is observed in CMIP5 models, WW (CAO) frequency is typically overestimated (underestimated). All models considered are unable to replicate observed associations between ATRs and the PDO. Further, the collective influence of low-frequency modes upon ATRs is generally underestimated in CMIP5 models. The results indicate that predictions of future ATR behavior are limited by climate model ability to represent the evolving behavior of low-frequency modes of variability.

Proposed Criteria for Low Frequency Industrial Noise in Residential Communities

2005 ◽  
Vol 24 (2) ◽  
pp. 97-105 ◽  
Author(s):  
George F. Hessler
Keyword(s):  
United States ◽  
Low Frequency ◽  
The United States ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Residential Areas ◽  
Noise Sources ◽  
Residential Communities ◽  
Open Cycle ◽  
Industrial Sources

There is a need in the United States for some Federal or prominent standards organization to publish limits in residential areas for low frequency noise attributable to industrial sources. This paper proposes maximum limits based on experience in investigating and solving low frequency noise problems, principally from open cycle combustion turbine installations The author believes the recommended C-weighted limits in this paper are applicable to most common steady low-frequency noise sources in addition to combustion turbines due to the combined tonal and broadband character of the sound. It is hoped standardizing bodies can add this reference to the larger body of literature to arrive at a workable sorely-needed standard.

scholarly journals VLF surface-impedance measurements for ice-depth mapping — an assessment of some commonly encountered interference effects

1996 ◽  
Vol 42 (140) ◽  
pp. 33-36
Author(s):  
David V. Thiel ◽  
Daniel James ◽  
Peter Johnson
Keyword(s):  
Surface Impedance ◽  
Apparent Resistivity ◽  
Low Frequency ◽  
Two Dimensional ◽  
Interference Effects ◽  
Impedance Measurements ◽  
Very Low Frequency ◽  
Dimensional Boundary ◽  
Lateral Variations ◽  
Made In

AbstractThe effects on very low-frequency surface-impedence measurements of lateral variations commonly found in ice environments have been measured and modelled numerically using die quasi-static two-dimensional boundary-element method. Results indicate that surface-impedance measurements made in the vicinity of crevasses oriented perpendicular to the plane Of incidence, and those made in the vicinity of moraines and melt streams, can all show significant changes to the measured apparent resistivity. It is, therefore, misleading to use such measurements in the interpretation of ice depth.

Seismic Monitoring during Crises at the NEIC in Support of the ANSS

2021 ◽  
Author(s):  
Paul S. Earle ◽  
Harley M. Benz ◽  
William L. Yeck ◽  
Gavin P. Hayes ◽  
Michelle R. Guy ◽  
...  
Keyword(s):  
United States ◽  
Puerto Rico ◽  
Low Frequency ◽  
Strong Motion ◽  
The United States ◽  
Software Systems ◽  
Storm Damage ◽  
Volcano Observatory ◽  
The Face ◽  
Seismic Networks

Abstract Over the past two decades, the U.S. Geological Survey (USGS) National Earthquake Information Center (NEIC) has overcome many operational challenges. These range from minor disruptions, such as power outages, to significant operational changes, including system reconfiguration to handle unique earthquake sequences and the need to handle distributed work during a pandemic. Our ability to overcome crises is built on the development and implementation of a continuity of operations plan, well-designed infrastructure, adaptive software systems, experienced staff, and extensive collaboration. The NEIC does not operate in a vacuum but benefits from contributions of United States and international seismic networks. Similarly, the overall resilience of earthquake monitoring in the United States and around the globe benefits from the NEIC’s role as the national center for the Advanced National Seismic System (ANSS). Here, we highlight significant adaptations the NEIC has made in the face of crises. We discuss the COVID-19 pandemic, which represents the most significant operational crisis to impact the NEIC. The NEIC has maintained continuous operations during the ongoing COVID-19 pandemic by shifting from a fully onsite operations center to a distributed hybrid of onsite and telework staffing. We then discuss cases in which the NEIC has supported regional monitoring in the face of significant crises. In 2018, the NEIC assisted the Hawaiian Volcano Observatory with the Kīlauea volcano eruption by responding to large events, implementing contingency monitoring procedures, and calculating moment magnitudes for the low-frequency caldera collapses. Impacts of a crisis extend beyond the immediate response and often require a significant postevent assessment and a rebuilding phase. After the 2017 Hurricane Maria, the NEIC, the USGS National Strong-Motion Program, and the USGS Albuquerque Seismological Laboratory worked with the Puerto Rico Seismic Network and the Puerto Rico Strong-Motion program to assess, plan, and implement upgrades at sites that experienced storm damage.

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