The Thermal Noise Limit in the Detection of Acoustic Signals in Water

1951 ◽  
Vol 23 (5) ◽  
pp. 625-625
Author(s):  
R. H. Mellen
Keyword(s):  
Thermal Noise ◽  
Acoustic Signals ◽  
Noise Limit

EFFECT OF CELLULAR MEMBRANE RESISTIVITY INHOMOGENEITY ON THE THERMAL NOISE-LIMIT

2015 ◽  
Vol 11 (3) ◽  
pp. 3171-3183
Author(s):  
Gyula Vincze
Keyword(s):  
Field Strength ◽  
Thermal Noise ◽  
Cellular Membrane ◽  
Thermal Limit ◽  
Low Frequencies ◽  
Membrane Resistivity ◽  
Noise Limit ◽  
The Asymmetry ◽  
Characteristic Field

Our objective is to generalize the Weaver-Astumian (WA) and Kaune (KA) models of thermal noise limit to the case ofcellular membrane resistivity asymmetry. The asymmetry of resistivity causes different effects in the two models. In the KAmodel, asymmetry decreases the characteristic field strength of the thermal limit over and increases it below the breakingfrequency (10  m), while asymmetry decreases the spectral field strength of the thermal noise limit at all frequencies.We show that asymmetry does not change the character of the models, showing the absence of thermal noise limit at highand low frequencies in WA and KA models, respectively.

scholarly journals Nano-Kelvin Thermometry and Temperature Control: Beyond the Thermal Noise Limit

2014 ◽  
Vol 112 (16) ◽  
Author(s):  
Wenle Weng ◽  
James D. Anstie ◽  
Thomas M. Stace ◽  
Geoff Campbell ◽  
Fred N. Baynes ◽  
...  
Keyword(s):  
Temperature Control ◽  
Thermal Noise ◽  
Noise Limit

On the thermal noise limit of cellular membranes

2004 ◽  
Vol 26 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Gy. Vincze ◽  
N. Szasz ◽  
A. Szasz
Keyword(s):  
Thermal Noise ◽  
Cellular Membranes ◽  
Noise Limit

The Response of Living Cells to Very Weak Electric Fields: The Thermal Noise Limit

Science ◽  
1990 ◽  
Vol 247 (4946) ◽  
pp. 1019-1019 ◽  
Author(s):  
J. C. Weaver ◽  
R. D. Astumian
Keyword(s):  
Electric Fields ◽  
Thermal Noise ◽  
Living Cells ◽  
Noise Limit

scholarly journals Source counts and confusion at 72–231 MHz in the MWA GLEAM survey

2019 ◽  
Vol 36 ◽  
Author(s):  
T. M. O. Franzen ◽  
T. Vernstrom ◽  
C. A. Jackson ◽  
N. Hurley-Walker ◽  
R. D. Ekers ◽  
...  
Keyword(s):  
Thermal Noise ◽  
Low Frequency ◽  
Radio Continuum ◽  
Large Area ◽  
Design Study ◽  
Array Design ◽  
Square Kilometre Array ◽  
Noise Limit ◽  
Murchison Widefield Array ◽  
Extended Emission

Abstract The GaLactic and Extragalactic All-sky Murchison Widefield Array survey is a radio continuum survey at 72–231 MHz of the whole sky south of declination +30º, carried out with the Murchison Widefield Array. In this paper, we derive source counts from the GaLactic and Extragalactic All-sky Murchison data at 200, 154, 118, and 88 MHz, to a flux density limit of 50, 80, 120, and 290 mJy respectively, correcting for ionospheric smearing, incompleteness and source blending. These counts are more accurate than other counts in the literature at similar frequencies as a result of the large area of sky covered and this survey’s sensitivity to extended emission missed by other surveys. At S154 MHz > 0.5 Jy, there is no evidence of flattening in the average spectral index (α ≈ −0.8 where S ∝ vα) towards the lower frequencies. We demonstrate that the Square Kilometre Array Design Study model by Wilman et al. significantly underpredicts the observed 154-MHz GaLactic and Extragalactic All-sky Murchison counts, particularly at the bright end. Using deeper Low-Frequency Array counts and the Square Kilometre Array Design Study model, we find that sidelobe confusion dominates the thermal noise and classical confusion at v ≳ 100 MHz due to both the limited CLEANing depth and the undeconvolved sources outside the field-of-view. We show that we can approach the theoretical noise limit using a more efficient and automated CLEAN algorithm.

scholarly journals MultiView High Precision VLBI Astrometry at Low Frequencies

2017 ◽  
Vol 13 (S336) ◽  
pp. 439-442
Author(s):  
M. Rioja ◽  
R. Dodson ◽  
G. Orosz ◽  
H. Imai
Keyword(s):  
High Precision ◽  
Thermal Noise ◽  
Angular Separation ◽  
Low Frequencies ◽  
Ionospheric Propagation ◽  
Propagation Effects ◽  
Order Of Magnitude ◽  
Noise Limit ◽  
Single Epoch ◽  
Magnitude Improvement

AbstractObservations at low frequencies (<8GHz) are dominated by distinct direction dependent ionospheric propagation errors, which place a very tight limit on the angular separation of a suitable phase referencing calibrator and astrometry. To increase the capability for high precision astrometric measurements an effective calibration strategy of the systematic ionospheric propagation effects that is widely applicable is required. The MultiView technique holds the key to the compensation of atmospheric spatial-structure errors, by using observations of multiple calibrators and two dimensional interpolation. In this paper we present the first demonstration of the power of MultiView using three calibrators, several degrees from the target, along with a comparative study of the astrometric accuracy between MultiView and phase-referencing techniques. MultiView calibration provides an order of magnitude improvement in astrometry with respect to conventional phase referencing, achieving ~100micro-arcseconds astrometry errors in a single epoch of observations, effectively reaching the thermal noise limit.

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