Exploiting phase coherence for improved resolution in optical atomic frequency ratios

Author(s):  
Tara M. Fortier
1961 ◽  
Vol 75 (9) ◽  
pp. 3-59 ◽  
Author(s):  
N.G. Basov ◽  
Oleg N. Krokhin ◽  
A.N. Oraevskii ◽  
G.M. Strakhovskii ◽  
B.M. Chikhachev

2019 ◽  
Vol 15 (S356) ◽  
pp. 348-350
Author(s):  
Eva Šrámková ◽  
K. Goluchová ◽  
G. Török ◽  
Marek A. Abramowicz ◽  
Z. Stuchlík ◽  
...  

AbstractA strong quasi-periodic modulation has recently been revealed in the X-ray flux of the X-ray source XMMUJ134736.6+173403. The two observed twin-peak quasiperiodic oscillations (QPOs) exhibit a 3:1 frequency ratio and strongly support the evidence for the presence of an active galactic nucleus black hole (AGN BH). It has been suggested that detections of twin-peak QPOs with commensurable frequency ratios and scaling of their periods with BH mass could provide the basis for a method intended to determine the mass of BH sources, such as AGNs. Assuming the orbital origin of QPOs, we calculate the upper and lower limit on the AGN BH mass M, reaching M ≍ 107–109M⊙. Compared to mass estimates of other sources, XMMUJ134736.6+173403 appears to be the most massive source with commensurable QPO frequencies, and its mass represents the current observational upper limit on the AGN BH mass obtained from the QPO observations.


2021 ◽  
pp. 030573562098727
Author(s):  
Pedro Neto ◽  
Patricia M Vanzella

We report an experiment in which participants ( N = 368) were asked to differentiate between major and minor thirds. These intervals could either be formed by diatonic tones from the C major scale (tonal condition) or by a subset of tones from the chromatic scale (atonal condition). We hypothesized that in the tonal condition intervals would be perceived as a function of scale step distances, which we defined as the number of diatonic leaps between two notes of a given music scale. In the atonal condition, we hypothesized that intervals would be perceived as a function of cents. If our hypotheses were supported, we should verify a less accurate performance in the tonal condition, where scale step distances are the same between major and minor thirds. The data corroborated our hypotheses, and we suggest that acoustic measurements of intervallic distances (i.e., frequency ratios and cents) are not optimal when it comes to describing the perceptual quality of intervals in a tonal context. Finally, our research points to the possibility that, in comparison with previous models, scale steps and cents might better capture the notion of global versus local instances of auditory processing.


2018 ◽  
Vol 36 (3) ◽  
pp. 937-943 ◽  
Author(s):  
Maurício J. A. Bolzan ◽  
Clezio M. Denardini ◽  
Alexandre Tardelli

Abstract. The geomagnetic field in the Brazilian sector is influenced by the South American Magnetic Anomaly (SAMA) that causes a decrease in the magnitude of the local geomagnetic field when compared to other regions in the world. Thus, the magnetometer network and data set of space weather over Brazil led by Embrace are important tools for promoting the understanding of geomagnetic fields over Brazil. In this sense, in this work we used the H component of geomagnetic fields obtained at different sites in South America in order to compare results from the phase coherence obtained from wavelet transform (WT). Results from comparison between Cachoeira Paulista (CXP) and Eusébio (EUS), and Cachoeira Paulista and São Luis (SLZ), indicated that there exist some phenomena that occur simultaneously in both locations, putting them in the same phase coherence. However, there are other phenomena putting both locations in a strong phase difference as observed between CXP and Rio Grande, Argentina (RGA). This study was done for a specific moderate geomagnetic storm that occurred in March 2003. The results are explained in terms of nonlinear interaction between physical phenomena acting in distinct geographic locations and at different times and scales. Keywords. Geomagnetism and paleomagnetism (time variations – diurnal to secular)


NeuroImage ◽  
2016 ◽  
Vol 137 ◽  
pp. 178-187 ◽  
Author(s):  
Baltazar Zavala ◽  
Huiling Tan ◽  
Keyoumars Ashkan ◽  
Thomas Foltynie ◽  
Patricia Limousin ◽  
...  

2017 ◽  
Vol 87 ◽  
pp. 31-37 ◽  
Author(s):  
J.F. Cruza ◽  
J. Camacho ◽  
C. Fritsch

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