Preservation of fertility in men with brain tumors

Currently, there is a steady increase in the number of oncological diseases, including the central nervous system (CNS). The number of newly diagnosed tumors of the central nervous system annually grows by 1—2%. However, the progress achieved in clinical neuro-oncology over the past decades has allowed a significant increase in patient survival rates without deterioration in the quality of life. The largest number of patients with brain tumors are people of reproductive age who are interested in maintaining fertility. Despite the improvement of neurosurgical techniques and radiation therapy, the use of modern chemotherapy regimens, patients still have the risk of reducing reproductive potential in the outcome of treatment. One of the most reliable methods for preserving male fertility is currently cryopreservation of sperm. It is important to inform patients with brain tumors about the possible risk of hypogonadism, infertility and the possibility of cryopreservation of sperm, which increases the chances of having genetic progeny in the future. © 2019, Media Sfera. All rights reserved

Rarefied Pure Gas Transport in Non-isothermal Porous Media: Validation and Tests of the Model

Viscous flow, effusion, and thermal transpiration are the main gas transport modalities for a rarefied gas in a macro-porous medium. They have been well quantified only in the case of simple geometries. This paper presents a numerical method based on the homogenization of kinetic equations producing effective transport properties (permeability, Knudsen diffusivity, thermal transpiration ratio) in any porous medium sample, as described by a digitized 3D image. The homogenization procedure -- neglecting the effect of gas density gradients on heat transfer through the solid -- leads to closure problems in R^6 for the obtention of effective properties ; they are then simplified using a Galerkin method based on a 21-element basis set. The kinetic equations are then discretized in R^3 space with a finite-volume scheme. The method is validated against experimental data in the case of a closed test tube. It shows to be coherent with past approaches of thermal transpiration. Then, it is applied to several 3D images of increasing complexity. Another validation is brought by comparison with other distinct numerical approaches for the evaluation of the Darcian permeability tensor and of the Knudsen diffusion tensor. Results show that thermal transpiration has to be described by an effective transport tensor which is distinct from the other tensors