scholarly journals Quiet-Filament Eruptions and Coronal Jets as Causes of Depressions in Microwave Radio Emission

2021 ◽  
Vol 65 (12) ◽  
pp. 1254-1264
Author(s):  
I. V. Kuzmenko
Keyword(s):  
Radio Emission ◽  
Low Frequencies ◽  
High Frequencies ◽  
Us Air Force ◽  
The Us ◽  
Microwave Radio ◽  
Using Data ◽  
Spectral Ranges ◽  
Rare Phenomena ◽  
Academy Of Sciences

Abstract Several solar events with different types of negative microwave bursts have been studied using data from different spectral ranges. The total radio flux data obtained at the Ussuriysk Observatory, the Nobeyama Observatory, the US Air Force Radio Solar Telescope Network (RSTN), and the spectropolarimeter of the Institute of Solar–Terrestrial Physics, Siberian Branch of the Russian Academy of Sciences (ISTP SB RAS) were used. The images were analyzed using data from the SDO/AIA space observatory in the 304 Å channel and the Nobeyama radio heliograph at a frequency of 17 GHz. It was shown that the “isolated” depressions of radio emission were caused by the absorption of radiation from radio sources and/or vast regions of the quiet Sun by low-temperature material of a large eruptive filament in the absence of flares. This confirmed the conclusions of the previous studies. It was revealed that the cause of negative bursts of the “pre-burst depression” type was the screening of a near-limb radio source by the material of coronal jets. In the case of a weak flare accompanying the jet, the negative burst could also be of the “isolated” type. A case of a previously unreported occurrence of a deeper depression of radio emission at high frequencies as compared to low frequencies was considered. It was shown that negative bursts are not as rare phenomena as previously thought.

Subspace Approach to Inversion by Genetic Algorithms Involving Multiple Frequencies

1998 ◽  
Vol 06 (01n02) ◽  
pp. 99-115 ◽  
Author(s):  
Purnima Ratilal ◽  
Peter Gerstoft ◽  
Joo Thiam Goh
Keyword(s):  
Genetic Algorithms ◽  
Model Parameters ◽  
Data Sets ◽  
A Posteriori ◽  
Low Frequencies ◽  
High Frequencies ◽  
Estimated Parameters ◽  
Wide Range ◽  
Multiple Frequencies ◽  
Using Data

Based on waveguide physics, a subspace inversion approach is proposed. It is observed that the ability to estimate a given parameter depends on its sensitivity to the acoustic wavefield, and this sensitivity depends on frequency. At low frequencies it is mainly the bottom parameters that are most sensitive and at high frequencies the geometric parameters are the most sensitive. Thus, the parameter vector to be determined is split into two subspaces, and only part of the data that is most influenced by the parameters in each subspace is used. The data sets from the Geoacoustic Inversion Workshop (June 1997) are inverted to demonstrate the approach. In each subspace Genetic Algorithms are used for the optimization — it provides flexibility to search over a wide range of parameters and also helps in selecting data sets to be used in the inversion. During optimization, the responses from many environmental parameter sets are computed in order to estimate the a posteriori probabilities of the model parameters. Thus the uniqueness and uncertainty of the model parameters are assessed. Using data from several frequencies to estimate a smaller subspace of parameters iteratively provides stability and greater accuracy in the estimated parameters.

scholarly journals Compact Doubles: A Genuine or Illusory Class?

1984 ◽  
Vol 110 ◽  
pp. 63-64
Author(s):  
R. B. Phillips ◽  
M. W. Hodges ◽  
R. L. Mutel
Keyword(s):  
Radio Emission ◽  
Relativistic Effects ◽  
The Other ◽  
Spectral Indices ◽  
Low Frequencies ◽  
High Frequencies ◽  
The Core ◽  
Initial Discovery ◽  
5 Ghz

Symmetric, two-sided morphology seems to argue against relativistic effects dominating compact radio emission. This kind of structure has been reported for a number of sources (Phillips and Mutel 1982; Pearson 1983) based on maps made at one frequency. Various arguments, all indirect, can be made for these sources being (1) Twin regions formed at the ends of jets which emerge from an invisible core, or (2) misidentified core-jet sources wherein the core and an unusually bright knot are wrongly taken to be a “double.” A telling test of both hypotheses is to map the sources in question over an octave or so of frequency. Proponents of view (1) would predict that the two double components will show nearly identical spectral indices and that weak central cores with flat or rising spectra might even be revealed. Champions of view (2) would predict that one end or the other will dominate at high frequencies (the core!) or that complex bridges of emission (the jet!) will be revealed between the components at low frequencies. We have followed our initial discovery of 5 symmetric compact doubles by (A) attempting to enlarge the sample of symmetric sources available to study, and (B) by investigating at 5 GHz those doubles for which the best maps exist at 1.7 GHz.

scholarly journals Unravelling the Multiple Component Radio Emission of RS OPH in Outburst

1988 ◽  
Vol 103 ◽  
pp. 335-336
Author(s):  
A.R. Taylor ◽  
M.F. Bode ◽  
R.J. Davis ◽  
R.W. Porcas
Keyword(s):  
Radio Emission ◽  
Physical Properties ◽  
Low Frequencies ◽  
High Frequencies ◽  
Vlbi Observations ◽  
Multiple Component

AbstractVLBI observations of RS Ophiuchi during its 1985 outburst enable us to start to disentangle the multiple component radio emission. It appears that the emission at low frequencies was predominantly non–thermal, whereas at high frequencies the emission is most likely thermal. It is then possible to probe the physical properties of the remnant.

EXPRESS: Commercial Success through Commercials? Advertising and Pay TV Operators

2021 ◽  
pp. 002224372110281
Author(s):  
Joonhyuk Yang ◽  
Jung Youn Lee ◽  
Pradeep K. Chintagunta
Keyword(s):  
Television Advertising ◽  
Service Market ◽  
Unit Costs ◽  
Cost Efficiencies ◽  
Pay Television ◽  
National Advertising ◽  
The Us ◽  
Television Service ◽  
Asymmetric Cost ◽  
Using Data

The US pay television service market had been dominated by cable operators until the nationwide entry of satellite operators in the early 1990s. The latter have been consistently growing their footprints since. This study documents the role of television advertising to explain the success. Using data on US households’ subscription choices and operators’ advertising decisions, the authors document both demand- and supply-side conditions conducive to the growth of the satellite operators. First, the authors find consumers in this market were sensitive to advertising, and especially so to that of the satellite operators (ad-elasticities of about .05-.06 for satellite operators vs. .02 for cable operators). The authors employ a border strategy to demonstrate advertising-elastic demand and discuss its robustness to potential threats to identification. Second, the authors provide suggestive evidence that a form of asymmetric cost efficiencies in television advertising benefited the entrants more than the incumbents. Specifically, the unit costs of local advertising tend to be higher than of national advertising, which likely allowed the satellite operators to better leverage their national presence with (cheaper) national advertising. Overall, this study highlights the interaction between advertising efficiencies and the scale of entry in explaining the competition between market incumbents and entrants.

scholarly journals Measuring Historical Urban Neighborhood Sustainability: America’s Grand Avenues

2021 ◽  
Vol 13 (3) ◽  
pp. 1358
Author(s):  
Michael R. Greenberg
Keyword(s):  
New York ◽  
New York City ◽  
Kansas City ◽  
White Supremacy ◽  
Urban Neighborhood ◽  
Industrial Cities ◽  
The Us ◽  
Education Medical ◽  
Using Data ◽  
Us Cities

From 1850 through approximately 1920, wealthy entrepreneurs and elected officials created “grand avenues” lined by mansions in New York City, Chicago, Detroit, and other developing US cities. This paper examines the birthplaces of grand avenues to determine whether they have remained sustainable as magnets for healthy and wealthy people. Using data from the US EPA’s EJSCREEN system and the CDC’s 500 cities study across 11 cities, the research finds that almost every place where a grand avenue began has healthier and wealthier people than their host cities. Ward Parkway in Kansas City and New York’s Fifth Avenue have continued to be grand. Massachusetts Avenue in Washington, D.C., Richmond’s Monument Avenue, St. Charles Avenue in New Orleans, and Los Angeles’s Wilshire Boulevard are national and regional symbols of political power, culture and entertainment, leading to sustainable urban grand avenues, albeit several are challenged by their identification with white supremacy. Among Midwest industrial cities, Chicago’s Prairie Avenue birthplace has been the most successful, whereas the grand avenues of St. Louis, Cleveland, Detroit, and Buffalo have struggled, trying to use higher education, medical care, and entertainment to try to rebirth their once pre-eminent roles in their cities.

Absence of the weekend effect and industry-style portfolios

2019 ◽  
Vol 12 (4) ◽  
pp. 463-475
Author(s):  
Selma Izadi ◽  
Abdullah Noman
Keyword(s):  
New York ◽  
Stock Market ◽  
Structural Breaks ◽  
Stock Exchange ◽  
Structural Break ◽  
Weekend Effect ◽  
Content Type ◽  
Market Portfolio ◽  
The Us ◽  
Using Data

Purpose The existence of the weekend effect has been reported from the 1950s to 1970s in the US stock markets. Recently, Robins and Smith (2016, Critical Finance Review, 5: 417-424) have argued that the weekend effect has disappeared after 1975. Using data on the market portfolio, they document existence of structural break before 1975 and absence of any weekend effects after that date. The purpose of this study is to contribute some new empirical evidences on the weekend effect for the industry-style portfolios in the US stock market using data over 90 years. Design/methodology/approach The authors re-examine persistence or reversal of the weekend effect in the industry portfolios consisting of The New York Stock Exchange (NYSE), The American Stock Exchange (AMEX) and The National Association of Securities Dealers Automated Quotations exchange (NASDAQ) stocks using daily returns from 1926 to 2017. Our results confirm varying dates for structural breaks across industrial portfolios. Findings As for the existence of weekend effects, the authors get mixed results for different portfolios. However, the overall findings provide broad support for the absence of weekend effects in most of the industrial portfolios as reported in Robins and Smith (2016). In addition, structural breaks for other weekdays and days of the week effects for other days have also been documented in the paper. Originality/value As far as the authors are aware, this paper is the first research that analyzes weekend effect for the industry-style portfolios in the US stock market using data over 90 years.

Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam

2015 ◽  
Vol 804 ◽  
pp. 25-29 ◽  
Author(s):  
Wanlop Harnnarongchai ◽  
Kantima Chaochanchaikul
Keyword(s):  
Natural Rubber ◽  
Cell Size ◽  
Cell Morphology ◽  
Foam Cell ◽  
Adsorption Coefficient ◽  
Low Frequencies ◽  
Potassium Oleate ◽  
High Frequencies ◽  
Blowing Agent ◽  
Open Cell Foam

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.

scholarly journals Frequency of Antimicrobial Resistance in Shiga Toxin-Producing Escherichia coli (STEC) and Non-Typhoidal Salmonella (NTS) Clinical Infections and Association with Epidemiological Factors

2017 ◽  
Vol 4 (suppl_1) ◽  
pp. S366-S366
Author(s):  
Sanjana Mukherjee ◽  
Rebekah Mosci ◽  
Chase Anderson ◽  
Brian Snyder ◽  
James Collins ◽  
...  
Keyword(s):  
Continuous Monitoring ◽  
Antibiotic Prescription ◽  
Epidemiological Data ◽  
Chi Square ◽  
Surveillance Network ◽  
High Frequencies ◽  
Drug Classes ◽  
The Us ◽  
Prescription Rates ◽  
Foodborne Infections

Abstract Background STEC and NTS are leading causes of foodborne infections in the US. Monitoring resistance in these pathogens is essential to understand the distribution of resistance profiles and because of the high likelihood of horizontal transfer of resistance genes to other pathogens. Data involving resistance in clinical STEC and NTS isolates from Michigan is lacking. Methods Clinical STEC (n = 353) and NTS (n = 148) isolates from the MDHHS (2010–2014) were examined for resistance using disk diffusion, E-test or broth microdilution. Case information and epidemiological data for STEC isolates was extracted and associations with resistant infections were determined using chi square tests in SAS 9.3 and EpiInfo™ 7. Results Overall, 31 (8.8%, n = 353) STEC isolates were resistant to at least one antibiotic; high frequencies of resistance were observed for ampicillin (7.4%) and trimethoprim-sulfamethoxazole (4.0%). Resistance to ciprofloxacin (0.28%) and all three drug classes (0.28%) was less common. Preliminary results indicate that O157 resistance to ampicillin (4.8%) and trimethoprim-sulfamethoxazole (3.4%) was higher in Michigan compared with national frequencies (ampicillin = 2.7%, trimethoprim-sulfamethoxazole= 1.5%). Higher resistance frequencies were also observed in counties with high (11.3%) vs. low (7.7%) antibiotic prescription rates. For NTS, 23 (15.5%) isolates were resistant to ≥1 antibiotic. Resistance varied by serotype with high frequencies in Typhimurium (20%, n = 20), Newport (17.6%, n = 17) and Enteritidis (4.8%, n = 42); 11 (7.4%) NTS isolates were resistant to ≥3 antimicrobial classes. Conclusion Continuous monitoring of resistance in clinical STEC and NTS is warranted due to their importance as food pathogens. The identification of risk factors for resistance is crucial to develop alternative prevention practices to reduce the health burden of resistant infections in Michigan, which is not part of the FoodNet surveillance network. Disclosures All authors: No reported disclosures.

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