Local rigidity for actions of Kazhdan groups on non commutative LpL_p-spaces

Given a discrete group $\Gamma$, a finite factor $\mathcal N$ and a real number $p\in [1, +\infty)$ with $p\neq 2,$ we are concerned with the rigidity of actions of $\Gamma$ by linear isometries on the $L_p$-spaces $L_p(\mathcal N)$ associated to $\mathcal N$. More precisely, we show that, when $\Gamma$ and $\mathcal N$ have both Property (T) and under some natural ergodicity condition, such an action $\pi$ is locally rigid in the group $G$ of linear isometries of $L_p(\mathcal N)$, that is, every sufficiently small perturbation of $\pi$ is conjugate to $\pi$ under $G$. As a consequence, when $\Gamma$ is an ICC Kazhdan group, the action of $\Gamma$ on its von Neumann algebra ${\mathcal N}(\Gamma)$, given by conjugation, is locally rigid in the isometry group of $L_p({\mathcal N}(\Gamma)).$Comment: 20 page

Effect of gamma irradiation on the microbial load, chemical and sensory properties of goat meat

The present study was undertaken to assess the effects of gamma irradiation (0, 2, 4, and 6 kGy) on microbial, chemical, and sensory values of Jabaly Syrian goat meat during storage at 4 °C for 1, 3, 4, and 5 weeks. Irradiation was effective in reducing the microbial load and increasing the shelf-life of goat meat. The radiation doses required to reduce the microorganisms by 90 percent (D10) in goat meat were 294 and 400 Gy for Salmonella and E. coli, respectively. The main fatty acids identified from the goat meat were oleic, stearic, and palmitic acids. No significant differences were observed in moisture, crude protein, crude fat, ash, pH value, fatty acids, total acidity, volatile basic nitrogen, and sensory properties (texture, flavour, colour, and taste) of irradiated and non-irradiated goat meat. Lipid peroxidation measured in terms of thiobarbituric acid-reactive substances (TBARS) increased on irradiation and chilled storage. Sensory evaluation showed no significant differences between irradiated and non-irradiated goat meat

Energy release rate of small cracks under finite multiaxial straining

International audienceThe energy release rate of small cracks governs fatigue crack nucleation. A method is presented here to efficiently and accurately evaluate the energy release rate of such cracks, arbitrarily oriented, under general conditions of finite multiaxial loading. As a motivation, the dependence on crack length is then investigated. It is demonstrated that the energy release rate of small cracks is proportional to the crack length and that the proportionality factor is a function of the far-field parameters only. An attempt is then made to search for a general expression of this proportionality factor under simple loading conditions

Алгоритм определения оптимального числа волокон используемых при внутритканевой фотодинамической терапии рака молочной железы на основании диффузионного уравнения

It is essential in interstitial Photodynamic therapy (iPDT) treatment planning to ensure a homogeneous distribution within a tumor volume using cylindrical diffusing fibers while keeping the surrounding tissue intact. Light distribution is simulated through two algorithms based on the diffusion equation assuming diffusers as light sources. The first algorithm analyzes the diffusion equation and studies the effects of different variables (optical properties, delivered power, diffuser length, and position). Next, optical properties of breast were applied to estimate the volume that receives accepted light dose from one diffuser. In the second algorithm, multiple diffusers were simulated in order to find the relation between the volume and the number of required diffusers which are needed to cover cubical or cylindrical volume with sufficient light dose. Throughout this study, real values of optical properties, clinical laser power, and treatment time were considered to evaluate sufficient light doses. This study is in agreement with previous works in that optical properties are the major factors influencing light distribution in iPDT. It is shown that for a homogeneous phantom mimicking breast cancer and cubical or cylindrical shape, the number of required fibers N equal W×L or D2 respectively.При планировании внутритканевой фотодинамической терапии (iPDT ) с использованием цилиндрических диффузных волокон важно обеспечить однородное распределение света по всему объему опухоли, сохранив при этом целостность окружающей ткани. Авторы данной статьи смоделировали распределение света с помощью двух алгоритмов, основанных на уравнении диффузии, в которых в качестве источников света используются цилиндрические диффузоры. Первый алгоритм анализирует уравнение диффузии и изучает влияние различных переменных (оптических свойств источника, применяемой мощности, длины диффузора и его положения). Затем были использованы параметры оптических свойств молочной железы для оценки объема, который рассчитывает световую дозу от одного диффузора. Во втором алгоритме было смоделировано несколько рассеивателей для нахожде ния соотношения между объемом и количеством рассеивателей, необходимых для покрытия кубического или цилиндрического объема достаточной световой дозой. На протяжении всего этого исследования рассматривались реальные значения оптических свойств, клинической мощности лазера и времени лечения для оценки достаточных световых доз. Это исследование согласуется с предыдущими работами в том, что оптические свойства являются основными факторами, влияющими на распределение света при iPDT. Показано, что, для однородного фантома, имитирующего рак молочной железы, кубической или цилиндрической формы, количество требуемых волокон N равно W×L или D2 , соответственно

Energy release rate of small cracks under finite multiaxial straining

International audienceThe energy release rate of small cracks governs fatigue crack nucleation. A method is presented here to efficiently and accurately evaluate the energy release rate of such cracks, arbitrarily oriented, under general conditions of finite multiaxial loading. As a motivation, the dependence on crack length is then investigated. It is demonstrated that the energy release rate of small cracks is proportional to the crack length and that the proportionality factor is a function of the far-field parameters only. An attempt is then made to search for a general expression of this proportionality factor under simple loading conditions

BriFiSeg: a deep learning-based method for semantic and instance segmentation of nuclei in brightfield images

Generally, microscopy image analysis in biology relies on the segmentation of individual nuclei, using a dedicated stained image, to identify individual cells. However stained nuclei have drawbacks like the need for sample preparation, and specific equipment on the microscope but most importantly, and as it is in most cases, the nuclear stain is not relevant to the biological questions of interest but is solely used for the segmentation task. In this study, we used non-stained brightfield images for nuclei segmentation with the advantage that they can be acquired on any microscope from both live or fixed samples and do not necessitate specific sample preparation. Nuclei semantic segmentation from brightfield images was obtained, on four distinct cell lines with U-Net-based architectures. We tested systematically deep pre-trained encoders to identify the best performing in combination with the different neural network architectures used. Additionally, two distinct and effective strategies were employed for instance segmentation, followed by thorough instance evaluation. We obtained effective semantic and instance segmentation of nuclei in brightfield images from standard test sets as well as from very diverse biological contexts triggered upon treatment with various small molecule inhibitor. The code used in this study was made public to allow further use by the community