background: the shielding methods in radiotherapy due to delivering an accurate radiation dose to cancer tissues and avoiding unnecessary dose to normal tissues are very important. these methods include lead standard blocks, individual molding and multi leaf collimator (mlc). the mlc method is not still common in iran radiotherapy centers. individual molding is better than the lead block shield...

The oscillation of electrons, in a sufficiently intense pump wave, frustrates Debye shielding in the direction of the oscillation. One finds that such oscillating electrons cannot shield charge fluctuations over distances smaller than the distance they sample in a plasma period. One consequence is that the frequency of ion waves can be increased from the ion acoustic frequency to the ion plasma...

With the purpose of reducing stray radiation dose (SRD) in out-of-field region (OFR) during radiotherapy with 6 MV intensity-modulated radiation therapy (IMRT), a body-shielding device (BSD) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investi...

When considering the space limit of high energy LINAC facility in a hospital, the design of shielding wall is strongly required to optimize the wall thickness. Shielding wall usually consists of concrete, and iron plate is sometimes added in concrete to decrease the wall thickness. We investigated the optimum design of the shielding wall in medical LINAC facility by simulation. The calculations...

Katsumi Ohata* Junichi Sato* ABSTRACT: Magnetic shielding for strong magnets using a high-temperature superconductor that can be operated at liquid nitrogen temperature has been studied. Long and large-cross-section (9 mm wide and 0.5 mm thick) 54-filament Bi-2223/Ag tape was developed. Double pancake coils were wound using the tapes having sufficient bending strain tolerance for the react-and-...

In 1992, E.E.Podkletnov and R.Nieminen find that, under certain conditions, ceramic superconductor with composite structure has revealed weak shielding properties against gravitational force. In classical Newton’s theory of gravity and even in Einstein’s general theory of gravity, there are no grounds of gravitational shielding effects. But in quantum gauge theory of gravity, the gravitational ...

Parameter shielding refers to the situation that one test parameter disables others in test execution. The quality of test case generation techniques is limited by the wide existence of parameter shielding. It is challenging to automatically find out conditions that cause the parameter shielding. This paper presents a novel approach for exploring the shielding conditions of test parameters. Our...

In wild-type Caenorhabditis elegans hermaphrodites, two bilaterally symmetric sex myoblasts (SMs) migrate anteriorly to flank the precise center of the gonad, where they divide to generate the muscles required for egg laying (J. E. Sulston and H. R. Horvitz (1977) Devl Biol. 56, 110-156). Although this migration is largely independent of the gonad, a signal from the gonad attracts the SMs to th...

In 14 cases of the Turner syndrome and pure gonadal dysgenesis streak gonads were studied histologically. In cases where the 46,XX line was unimpaired the blood vessels of the gonad showed severe degeneration in at least 30 to 50%. These streak gonads usually contained some of the characteristic ovarian elements as well as the vascular lesions. In gonosomal monosomy, on the other hand, a simila...

Exposure to ionizing radiation in the space environment is one of the hazards faced by crews in space missions. As space radiations traverse spacecraft, habitat shielding, or tissues, their energies and compositions are altered by interactions with the shielding. Modifications to the radiation fields arise from atomic interactions of charged particles with orbital electrons and nuclear interact...