Visual evaluation of the effective thickness of lithium niobate phase plates using a crossed Wood-Scholz filter

2021 ◽  
Vol 88 (5) ◽  
pp. 236
Author(s):  
V. V. Krishtop ◽  
D. E. Savich ◽  
A. V. Popova ◽  
P. S. Goncharova ◽  
V. A. Maksimenko ◽  
...  

Author(s):  
William Krakow ◽  
Benjamin Siegel

Unwin has used a metallized non-conducting thread in the back focal plane of the objective lens that stops out a portion of the unscattered beam, takes on a localized positive charge and thus produces an additional phase shift to give a different transfer function of the lens. Under the particular conditions Unwin used, the phase contrast image was shifted to bright phase contrast for optimum focus.We have investigated the characteristics of this type of electrostatic phase plate, both analytically and experimentally, as functions of the magnitude of charge and defocus. Phase plates have been constructed by using Wollaston wire to mount 0.25μ diameter platinum wires across apertures ranging from 50 to 200μ diameter and vapor depositing SiO and gold on the mounted wires to give them the desired charging characteristics. The net charge was varied by adjusting only the bias on the Wehnelt shield of the gun, and hence the beam currents and effective size of the source.


2014 ◽  
Vol 24 (2) ◽  
pp. 67-76 ◽  
Author(s):  
Thomas Watterson ◽  
Lynn Marty Grames

The American Speech-Language-Hearing Association (ASHA) has developed Knowledge and Skills (KAS) recommendations for evaluation of the larynx and swallowing function but the evaluation of velopharyngeal (VP) function has never been addressed. This article will review previous documents that have addressed general endoscopic knowledge and skills and develop a case for a new KAS that specifically addresses visualization and evaluation of the VP mechanism. The new KAS document will delineate and explain the relationship between speech evaluation and visual evaluation of VP physiology. The unique skills required of the speech-language pathologist for this kind of evaluation will be discussed.


1994 ◽  
Author(s):  
George A. Geri ◽  
Don R. Lyon ◽  
Yehoshua Y. Zeevi
Keyword(s):  

2005 ◽  
Vol 126 ◽  
pp. 101-105 ◽  
Author(s):  
B. Moulin ◽  
L. Hennet ◽  
D. Thiaudière ◽  
P. Melin ◽  
P. Simon

2005 ◽  
Vol 44 (01) ◽  
pp. 29-32 ◽  
Author(s):  
I. Garai ◽  
J. Varga ◽  
G. Szücs ◽  
Z. Galajda ◽  
C. András ◽  
...  

Summary Aim: We investigated the circulatory characteristics of patients suffering of primary and secondary Raynaud’s syndrome. Patients, methods: We examined 106 patients presenting with the classical symptoms of Raynaud’s syndrom (47 primary, 59 secondary) by hand perfusion scintigraphy developed by our Department of Nuclear Medicine. After visual evaluation we analyzed the images semiquantitatively, using the finger to palm ratio. We statistically compared the patients with primary and those with secondary Raynaud’s syndrome. Results: By visual evaluation we constated regional perfusion disturbances in 42 from 59 patients with secondary Raynaud’s syndrome. However, this was observed in only 3 from 47 patients with the primary form of this disease. This difference was statistically significant (p <0.001). Semiquantitative analysis showed that the finger/palm ratios (FPR) were significantly lower (p <0.05) for the patients with primary Raynaud’s syndrome. No differences in the FPR values concerning sex or right and left side. Conclusion: The hand perfusion scintigraphy with 99mTc-DTPA is a noninvasive, cost effective diagnostic tool, which objectively reflects the global and regional microcirculatory abnormalities of the hands, and provides quantitative data for follow-up.


1993 ◽  
Author(s):  
KELLY PARMLEY ◽  
JOHN DANNENHOFFER, III ◽  
NIGEL WEATHERILL

2011 ◽  
Vol 25 (12) ◽  
pp. 1257-1262 ◽  
Author(s):  
Xiao-Niu TU ◽  
Yan-Qing ZHENG ◽  
Hui CHEN ◽  
Hai-Kuan KONG ◽  
Jun XIN ◽  
...  

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