ABSTRACT
The possibility to detect fast neutrons as a distinct signal from that one of γ-rays background is surely of great importance for several topics, spanning from homeland security to radiation monitoring in nuclear physics research plants. Nowadays, Helium-3 based detectors are extremely expensive, while the use of large volume liquid scintillators presents serious concerns related to spillage risks and waste disposal. A very attractive alternative is the use of commercially available solid scintillators, which exploits an aromatic polymer matrix entrapping very high loadings of primary dye, thereby enabling the use of pulse shape analysis (PSA) to discriminate between fast neutrons and γ-rays. In this work, we analyse in detail the optical features of a solid scintillator composed by polymethylphenylsiloxane (PMPS) as base polymer loaded with moderate amounts of 2,5-diphenyloxazole (PPO). Furthermore, fluorescence decay kinetics have been correlated to the observed pulse shape discrimination capabilities of this radiation and thermally resistant scintillator, whose performances have been discussed in terms of conformational features and excimers formation revealed by the optical analyses.
ABSTRACT
En la presente revisión abordamos un tema de especial importancia que ha sido pocas veces desarrollada en la bibliografía nacional de modo integral y por el cual el gastroenterólogo y el cirujano son frecuentemente consultados. Se hace una evaluación de los conceptos tradicionales y actuales de la Enfermedad Hemorroidal, con especial énfasis en las bases anatómicas y los mecanismos fisiopatológicos implicados, una revisión de las causas y la clasificación, se resaltan las manifestaciones clínicas y métodos de evaluación y diagnóstico y se toca con especial interés el enfoque terapéutico hasta hoy desarrollado a nivel mundial. Por último, pretendemos inculcar el término de Enfermedad Hemorroidal en reemplazo del mal usado Hemorroides