Histoire des doctrines socialistes

Deux ans après la publication par Salâma Mûsa d’un petit opuscule de tendance fabienne intitulé : Le socialisme (al-ishtirâkiyya) et en pleine guerre mondiale, un instituteur de province, Mustafâ Hasanayn al-Mansûrî, publie, en 1915, le premier ouvrage en langue arabe sur les origines et le développement de la pensée et des mouvements socialistes à travers le monde, avec lesquels il ne cache pas sa sympathie. L’intérêt du livre réside d’abord dans la singularité du fait ; ensuite, il intéress..

Histoire des doctrines socialistes

Deux ans après la publication par Salâma Mûsa d’un petit opuscule de tendance fabienne intitulé : Le socialisme (al-ishtirâkiyya) et en pleine guerre mondiale, un instituteur de province, Mustafâ Hasanayn al-Mansûrî, publie, en 1915, le premier ouvrage en langue arabe sur les origines et le développement de la pensée et des mouvements socialistes à travers le monde, avec lesquels il ne cache pas sa sympathie. L’intérêt du livre réside d’abord dans la singularité du fait ; ensuite, il intéress..

Le devenir de la sharî’a dans Le Second Message de M. M. Taha

Lorsqu’en janvier 1967, le Soudanais Mahmud Muhammad Taha publia son livre-manifeste Le Second Message (Al-risâla al-thâniya), rares étaient ceux qui, dans le monde arabe ou musulman, considéraient l’application de la sharî’a (c’est-à-dire le droit dit musulman) comme un programme politique pour lequel il fallait mobiliser la masse des jeunes. Le débat portait alors sur les relations contradictoires ou concordantes entre le “marxisme” (en fait la vulgate stalino-léniniste) et le “socialisme a..

Un disciple libre penseur de Al-Afghani : Adib Ishaq

Khayati Mustapha. Un disciple libre penseur de Al-Afghani : Adib Ishaq. In: Revue du monde musulman et de la Méditerranée, n°52-53, 1989. Les Arabes, les Turcs et la Révolution française. pp. 138-149

Brèves remarques sur le poème libertaire : «As-Sabr Liliah...» et son auteur

Khayati Mustapha. Brèves remarques sur le poème libertaire : «As-Sabr Liliah...» et son auteur. In: Revue du monde musulman et de la Méditerranée, n°51, 1989. Les prédicateurs profanes au Maghreb. pp. 137-142

Enhancing benefits of bolus use through minimising the effect of air-gaps on dose distribution in photon beam radiotherapy

AbstractIntroduction:Bolus material is frequently used on patient’s skin during radiation therapy to reduce or remove build-up effect for high-energy beams. However, the air-gaps formed between the bolus and the skin’s irregular surface reduce the accuracy of treatment planning. To achieve a good treatment outcome using bolus, experimental investigations are required to choose its thickness and to quantify the air-gap effect.Material and methods:Measurements for a 6 MV photon beam with a fixed source surface distance were carried out using the 31021 Semiflex 3D chamber into the water phantom. Firstly, the depth of maximum dose (R100) and the dose value at surface (Ds) were evaluated as a function of bolus thickness for some square fields. Secondly, to test the effect of the air-gaps ranged from 5 to 30 mm with a step of 5 mm between the bolus and the phantom surface, a water-equivalent RW3 (Goettingen White Water) slab form of 10 mm thickness was considered as a bolus.Results:We observed that the linear behaviour of R100 in terms of the bolus thickness makes the choice of this parameter more convenient depending on field size. In addition, increasing the air-gaps widens the penumbra and created electrons that have a greater probability to quit the radiation field borders before reaching the surface. The dose spread of the off-field area could have a significant influence on the patient treatment.Conclusion:Based on dose distribution comparisons between the measurements with and without air-gaps for the field size of 100 mm × 100 mm, it has been demonstrated that a maximum air-gap value lower than 5 mm would be desirable for an efficient use of the bolus technique.</jats:sec

Optimization of the iterative deconvolution correction method applied to ionization chamber response for small field dosimetry measurements

This study aims to optimize the iterative deconvolution correction of air-filled ionization chamber measurements with limited spatial resolution for photon beam dosimetry. The ionization chamber volume effect could be explained by the inhomogeneity of the absorbed dose in its sensitive volume, leading to a volume averaging effect acting as a convolution kernel $K(x)$. Therefore, the "true" dose profile $P_t(x)$ can be deduced by deconvolving measured 1D profiles $P_m(x)$. The Semiflex 3D ionization chamber type PTW 31021 was studied for beams with flattening filter (WFF), while the SNC125c ionization chamber was investigated for flattening filter free (FFF) beams. The deconvolution distributions were compared for the first ionization chamber with reference dose profiles calculated by Monte Carlo simulation and for the second ionization chamber with reference measurements obtained using a diode EDGE detector, suitable for small field applications. The convolution kernel was assumed to be a sum of normalized Gaussian and Lorentz distributions parametrized by the pair $(σ_{ic}λ_{ic})$. Good results were obtained with respect to the $γ_{index}$ 2.0%/0.5 mm criterion for the field sizes 6 × 6 mm2, 10 × 10 mm$^2$ and 20 × 20 mm$^2$. The highest agreement between reference and corrected measurement data was obtained by using the Gauss-Lorentz distribution parameters (1.92 mm, 0.80 mm) and (1.90 mm, 0.90 mm) for the ionization chambers Semiflex 3D type PTW 31021 and SNC125c, respectively