scholarly journals Lateral Structure Function of the Energy Density of Electrons in a Cascade Shower

1979 ◽  
Vol 61 (3) ◽  
pp. 895-902
Author(s):  
H. Oda
Keyword(s):  
Energy Density ◽  
Structure Function ◽  
Cascade Shower ◽  
Density Of Electrons ◽  
Lateral Structure

scholarly journals Precision Pulsar Timing in the Presence of Interstellar Weather – PSR B1937+21 and the Crab Pulsar

1996 ◽  
Vol 160 ◽  
pp. 87-90 ◽  
Author(s):  
D. C. Backer ◽  
T. Wong
Keyword(s):  
Structure Function ◽  
Column Density ◽  
Density Fluctuations ◽  
Crab Pulsar ◽  
Dual Frequency ◽  
Frequency Dependent ◽  
Pulsar Timing ◽  
Multipath Scattering ◽  
Density Of Electrons ◽  
Synchrotron Nebula

AbstractWe report on six months of dual-frequency, precision timing of PSR B1937+21 and the Crab pulsar. Variations in the column density of electrons – interstellar weather – are studied. The column is not unique in the presence of frequency-dependent multipath scattering, and this may explain the non-square law dependence of systematic timing residuals on B1937+21. The electron column density variations of the Crab pulsar are summarized in a structure function that ranges from 1012cm to 1015cm. These density fluctuations are located in the thermal shell surrounding the synchrotron nebula.

Log-log scale roughness spectroscopy of surfaces

1993 ◽  
Vol 51 ◽  
pp. 224-225
Author(s):  
P. Fraundorf ◽  
B. Armbruster
Keyword(s):  
Power Spectrum ◽  
Autocorrelation Function ◽  
Power Spectra ◽  
Scanning Force Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Scanning Force ◽  
Lateral Structure ◽  
Scale Roughness

Optical interferometry, confocal light microscopy, stereopair scanning electron microscopy, scanning tunneling microscopy, and scanning force microscopy, can produce topographic images of surfaces on size scales reaching from centimeters to Angstroms. Second moment (height variance) statistics of surface topography can be very helpful in quantifying “visually suggested” differences from one surface to the next. The two most common methods for displaying this information are the Fourier power spectrum and its direct space transform, the autocorrelation function or interferogram. Unfortunately, for a surface exhibiting lateral structure over several orders of magnitude in size, both the power spectrum and the autocorrelation function will find most of the information they contain pressed into the plot’s origin. This suggests that we plot power in units of LOG(frequency)≡-LOG(period), but rather than add this logarithmic constraint as another element of abstraction to the analysis of power spectra, we further recommend a shift in paradigm.

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