The Clinical Impact of Ultrasonic Beam Focusing Patterns

Radiology ◽  
1979 ◽  
Vol 131 (2) ◽  
pp. 469-472 ◽  
Author(s):  
C. Carl Jaffe ◽  
Kenneth J. W. Taylor
Author(s):  
Keisuke TSUKADA ◽  
Taiki AIBA ◽  
Tatsuya KAWAGUCHI ◽  
Hiroshige KIKURA ◽  
Katsuhiko SUGITA ◽  
...  

2009 ◽  
Author(s):  
H. Jeong ◽  
J.-S. Lee ◽  
Y.-H. Jeong ◽  
S.-M. Bae ◽  
C. H. Lee ◽  
...  

Author(s):  
Ryo Iiyoshi ◽  
Susumu Maruse ◽  
Hideo Takematsu

Point cathode electron gun with high brightness and long cathode life has been developed. In this gun, a straightened tungsten wire is used as the point cathode, and the tip is locally heated to higher temperatures by electron beam bombardment. The high brightness operation and some findings on the local heating are presented.Gun construction is shown in Fig.l. Small heater assembly (annular electron gun: 5 keV, 1 mA) is set inside the Wehnelt electrode. The heater provides a disk-shaped bombarding electron beam focusing onto the cathode tip. The cathode is the tungsten wire of 0.1 mm in diameter. The tip temperature is raised to the melting point (3,650 K) at the beam power of 5 W, without any serious problem of secondary electrons for the gun operation. Figure 2 shows the cathode after a long time operation at high temperatures, or high brightnesses. Evaporation occurs at the tip, and the tip part retains a conical shape. The cathode can be used for a long period of time. The tip apex keeps the radius of curvature of 0.4 μm at 3,000 K and 0.3 μm at 3,200 K. The gun provides the stable beam up to the brightness of 6.4×106 A/cm2sr (3,150 K) at the accelerating voltage of 50 kV. At 3.4×l06 A/cm2sr (3,040 K), the tip recedes at a slow rate (26 μm/h), so that the effect can be offset by adjusting the Wehnelt bias voltage. The tip temperature is decreased as the tip moves out from the original position, but it can be kept at constant by increasing the bombarding beam power. This way of operation is possible for 10 h. A stepwise movement of the cathode is enough for the subsequent operation. Higher brightness operations with the rapid receding rates of the tip may be improved by a continuous movement of the wire cathode during the operations. Figure 3 shows the relation between the beam brightness, the tip receding rate by evaporation (αis the half-angle of the tip cone), and the cathode life per unit length, as a function of the cathode temperature. The working life of the point cathode is greatly improved by the local heating.


2005 ◽  
Vol 173 (4S) ◽  
pp. 225-225
Author(s):  
Peter Olbert ◽  
Andres J. Schrader ◽  
Axel Hegele ◽  
Zoltan Varga ◽  
Axel Heidenreich ◽  
...  

2017 ◽  
Vol 22 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Bastianina Contena ◽  
Stefano Taddei

Abstract. Borderline Intellectual Functioning (BIF) refers to a global IQ ranging from 71 to 84, and it represents a condition of clinical attention for its association with other disorders and its influence on the outcomes of treatments and, in general, quality of life and adaptation. Furthermore, its definition has changed over time causing a relevant clinical impact. For this reason, a systematic review of the literature on this topic can promote an understanding of what has been studied, and can differentiate what is currently attributable to BIF from that which cannot be associated with this kind of intellectual functioning. Using Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) criteria, we have conducted a review of the literature about BIF. The results suggest that this condition is still associated with mental retardation, and only a few studies have focused specifically on this condition.


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