A rotating fan-beam radiation model for the pulse duration and frequency spectrum of pulsar radiation

2016 ◽  
Author(s):  
Michael J Underhill
Keyword(s):  
Pulse Duration ◽  
Frequency Spectrum ◽  
Radiation Model ◽  
Beam Radiation ◽  
Pulsar Radiation

scholarly journals On the Shape of the Pulsar Emission Diagram

1992 ◽  
Vol 128 ◽  
pp. 147-149
Author(s):  
I. M. Yusifov
Keyword(s):  
Observational Data ◽  
Radiation Pattern ◽  
Pulse Duration ◽  
Hollow Cone ◽  
Pulsar Emission ◽  
Pulsar Period ◽  
Cone Model ◽  
Pulsar Radiation

AbstractOn the basis of pulse profiles in a limited interval of wavelength for ~260 pulsars, the dependence of the shape and width of the pulsar radiation pattern on pulsar period is investigated. The relative pulse duration is compared with the ratio of numbers of single and multicomponent pulsars. It is shown that the simple circular hollow cone model does not agree with observational data. Preliminary estimates show that the young pulsars (with short periods) have an elliptical pattern which at long periods becomes circular.

In situ REM imaging of surface processes on ceramic bulk crystals from 300 to 1670 K in a conventional TEM

1991 ◽  
Vol 49 ◽  
pp. 660-661
Author(s):  
Z. L. Wang ◽  
J. Bentley
Keyword(s):  
High Temperatures ◽  
Image Resolution ◽  
Atomic Processes ◽  
Crystal Surfaces ◽  
Beam Radiation ◽  
Surface Areas ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Gas Reactions

Studying the behavior of surfaces at high temperatures is of great importance for understanding the properties of ceramics and associated surface-gas reactions. Atomic processes occurring on bulk crystal surfaces at high temperatures can be recorded by reflection electron microscopy (REM) in a conventional transmission electron microscope (TEM) with relatively high resolution, because REM is especially sensitive to atomic-height steps.Improved REM image resolution with a FEG: Cleaved surfaces of a-alumina (012) exhibit atomic flatness with steps of height about 5 Å, determined by reference to a screw (or near screw) dislocation with a presumed Burgers vector of b = (1/3)<012> (see Fig. 1). Steps of heights less than about 0.8 Å can be clearly resolved only with a field emission gun (FEG) (Fig. 2). The small steps are formed by the surface oscillating between the closely packed O and Al stacking layers. The bands of dark contrast (Fig. 2b) are the result of beam radiation damage to surface areas initially terminated with O ions.

Beam-radiation effects on wool in the ESEM

1986 ◽  
Vol 44 ◽  
pp. 674-675
Author(s):  
G.D. Danilatos
Keyword(s):  
Electron Beam ◽  
Radiation Effects ◽  
Research Work ◽  
Beam Radiation ◽  
Liquid Environment ◽  
Know How ◽  
Environmental Sem

The advent of the environmental SEM (ESEM) has made possible the examination of uncoated and untreated specimen surfaces in the presence of a gaseous or liquid environment. However, the question arises as to what degree the examined surface remains unaffected by the action of the electron beam. It is reasonable to assume that the beam invariably affects all specimens but the type and degree of effect may be totally unimportant for one class of applications and totally unacceptable for another; yet, for a third class, it is imperative to know how our observations are modified by the presence of the beam. The aim of this report is to create an awareness of the need to initiate research work in various fields in order to determine the guiding rules of the limitations (or even advantages) due to irradiation.

Bayesian removal of noise for increased sensitivity in vector pattern recognition lattice imaging of interfaces

1993 ◽  
Vol 51 ◽  
pp. 994-995
Author(s):  
L. Fei ◽  
P. Fraundorf
Keyword(s):  
Pattern Recognition ◽  
Perfect Crystal ◽  
Unit Cell ◽  
Ion Milling ◽  
Beam Radiation ◽  
Major Interest ◽  
Unit Cells ◽  
Mapping Process ◽  
Increased Sensitivity ◽  
Electron Microscopes

Interface structure is of major interest in microscopy. With high resolution transmission electron microscopes (TEMs) and scanning probe microscopes, it is possible to reveal structure of interfaces in unit cells, in some cases with atomic resolution. A. Ourmazd et al. proposed quantifying such observations by using vector pattern recognition to map chemical composition changes across the interface in TEM images with unit cell resolution. The sensitivity of the mapping process, however, is limited by the repeatability of unit cell images of perfect crystal, and hence by the amount of delocalized noise, e.g. due to ion milling or beam radiation damage. Bayesian removal of noise, based on statistical inference, can be used to reduce the amount of non-periodic noise in images after acquisition. The basic principle of Bayesian phase-model background subtraction, according to our previous study, is that the optimum (rms error minimizing strategy) Fourier phases of the noise can be obtained provided the amplitudes of the noise is given, while the noise amplitude can often be estimated from the image itself.

1141: A Randomized Controlled Trial Comparing External Beam Radiation and Cryoablation in Localized Prostate Cancer

2007 ◽  
Vol 177 (4S) ◽  
pp. 376-377 ◽  
Author(s):  
Bryan J. Donnelly ◽  
John C. Saliken ◽  
Penny Brasher ◽  
Scott Ernst ◽  
Harold Lau ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Randomized Controlled Trial ◽  
Controlled Trial ◽  
Localized Prostate Cancer ◽  
External Beam Radiation ◽  
External Beam ◽  
Beam Radiation ◽  
Randomized Controlled
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