DETERMINATION OF SIGNAL AND NOISE STATISTICS USING CORRELATION THEORY

Geophysics ◽  
1970 ◽  
Vol 35 (1) ◽  
pp. 24-32 ◽  
Author(s):  
Bibhu P. Dash ◽  
K. Ahmed Obaidullah
Keyword(s):  
Signal To Noise Ratio ◽  
Random Series ◽  
Signal To Noise ◽  
Time Duration ◽  
Optimum Time ◽  
Seismic Wavelet ◽  
Correlation Theory ◽  
Noise Ratio ◽  
Noise Statistics

A seismic trace may be represented as the sum of a signal and noise series. Each of the series may further be represented by convolution of a finite wavelet and a random series. With this representation, and provided that the signal and noise are uncorrelated, it is possible, in theory, to extract signal and noise statistics from two adjacent traces of a reflection seismogram. Some experiments are shown on model seismic traces, and it is shown that within the time‐duration of the seismic wavelet, the estimates of signal and noise statistics are reasonable for low signal‐to‐noise ratio. There remains, however, the problem of determining the optimum time lengths of the estimates.

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

Determination of trans-phylloquinone in children's serum.

1989 ◽  
Vol 35 (5) ◽  
pp. 874-878 ◽  
Author(s):  
F Moussa ◽  
L Dufour ◽  
J R Didry ◽  
P Aymard
Keyword(s):  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Fluorometric Detection ◽  
Vitamin K1 ◽  
Signal To Noise ◽  
Détection Signal ◽  
Coagulation Tests ◽  
Noise Ratio ◽  
Detection Signal

Abstract By optimizing the conditions for determining trans-phylloquinone and its metabolite, K-2,3-epoxide, in serum through a two-step HPLC process combined with fluorometric detection after coulometric reduction, we have been able to develop a method applicable to small volumes of serum (200 to 500 microL). The limit of detection (signal-to-noise ratio of 3) was 15 ng/L for trans-phylloquinone, 30 ng/L for K-2,3-epoxide. The trans-phylloquinone concentrations measured by this method in serum from 82 children, ages one to six years, whose results were normal for overall coagulation tests, ranged from 40 to 880 ng/L (median 175 ng/L). We discuss these findings and compare them with vitamin K1(20) values reported for adults.

scholarly journals Determination of best Raman spectroscopy spatial offsets for transcutaneous bone quality assessments in human hands

2021 ◽  
Author(s):  
Keren Chen ◽  
Christine Massie ◽  
Hani A Awad ◽  
Andrew J Berger
Keyword(s):  
Raman Spectroscopy ◽  
Bone Quality ◽  
Bone Fracture ◽  
Signal To Noise Ratio ◽  
Spectral Unmixing ◽  
Absolute Amount ◽  
Signal To Noise ◽  
Noise Ratio ◽  
Quality Assessments

Spatially offset Raman spectroscopy (SORS) is able to detect bone signal transcutaneously and could assist in predicting bone fracture risk. Criteria for optimal source-detector offsets for transcutaneous human measurements, however, are not well-established. Although larger offsets yield a higher percentage of bone signal, the absolute amount of bone signal decreases. Spectral unmixing into bone, adipose, and non-adipose components was employed to quantify changes in bone signal to noise ratio across a range of offsets, and optimal offsets for phalanx and metacarpal measurements were determined. The bone signal to noise ratio was maximized at offsets ranging from 4-6 mm.

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