Matrix probing: a randomized preconditioner for the wave-equation Hessian

This paper considers the problem of approximating the inverse of the wave-equation Hessian, also called normal operator, in seismology and other types of wave-based imaging. An expansion scheme for the pseudodifferential symbol of the inverse Hessian is set up. The coefficients in this expansion are found via least-squares fitting from a certain number of applications of the normal operator on adequate randomized trial functions built in curvelet space. It is found that the number of parameters that can be fitted increases with the amount of information present in the trial functions, with high probability. Once an approximate inverse Hessian is available, application to an image of the model can be done in very low complexity. Numerical experiments show that randomized operator fitting offers a compelling preconditioner for the linearized seismic inversion problem.Comment: 21 pages, 6 figure

A numerical study of super-resolution through fast 3D wideband algorithm for scattering in highly-heterogeneous media

International audienc

Des rencontres de proximité : apprendre de l’autre, pour tisser de la solidarité et de l’espoir. Première partie

Une équipe de proximité est née il y a plus de huit ans de préoccupations communes concernant la population des jeunes dits « de la rue », désaffiliés, en situation de grande précarité ou de rupture, et les intervenants qui vont à leur rencontre. Des rencontres de proximité qui ont su durer dans le temps, malgré des départs ou des changements et au gré de nouvelles arrivées. Un projet de partenariat, gravitant autour de valeurs et de principes communs. Un regroupement d’intervenants ayant à coeur l’amélioration des services à la population des jeunes exclus et marginalisés ou à risque de le devenir. Des intervenants de cette équipe, provenant de divers horizons et institutions, expliquent pourquoi ils y croient.A proximity team was created more than eight years ago by a group of health professionals working with disaffiliated and homeless youth in the most precarious of situations. Proximity meetings have continued since that time, despite many changes within the team, including departures and new arrivals. The proximity team is a partnership project which revolves around common values and principles aimed at improving services for youth who find themselves marginalized or at risk of exclusion. Health professionals from various backgrounds explain why they believe in this approach to proximity work.Un equipo de proximidad nació hace más de ocho años de preocupaciones comunes relacionadas con la población de jóvenes “de la calle”, sin afiliación, en situación muy precaria o de ruptura y los interventores que van a su encuentro. Los encuentros de proximidad perduraron en el tiempo, a pesar de las partidas o cambios y en función de los nuevos arribos. Un proyecto de cooperación que gravita alrededor de valores y principios comunes. Un reagrupamiento de interventores que toma a pecho la mejora de los servicios para la población de jóvenes excluidos y marginados o en riesgo de serlo. Los interventores de este equipo, provenientes de diversos horizontes e instituciones, explican por qué creen en ello.Uma equipe de proximidade foi criada há mais de oito anos a partir de preocupações comuns com respeito à população de jovens ditos “de rua”, sem filiação, em situação de grande precariedade ou de ruptura, e com respeito aos assistentes sociais que vão ao seu encontro. Estes encontros de proximidade perduraram, apesar das saídas ou das mudanças e ao sabor das novas chegadas. É um projeto de parceria que trata de valores e de princípios comuns: um agrupamento de assistentes sociais que valorizam a melhoria dos serviços prestados à população dos jovens excluídos e marginalizados ou que têm o risco de se tornarem assim. Os assistentes sociais desta equipe, vindo de diversos horizontes e instituições, explicam porque acreditam no projeto

Binding of a Soluble meso-Tetraarylporphyrin to Human Galectin-7 Induces Oligomerization and Modulates Its Pro-Apoptotic Activity

The selective targeting of protein-protein interactions remains a significant determinant for the proper modulation and regulation of cell apoptosis. Prototypic galectins such as human galectin-7 (GAL-7) are characterized by their ability to form homodimers that control the molecular fate of a cell by mediating subtle yet critical glycan-dependent interactions between pro- and anti-apoptotic molecular partners. Altering the structural architecture of GAL-7 can therefore result in resistance to apoptosis in various human cancer cells, further illustrating its importance in cell survival. In this study, we used a combination of biophysical and cellular assays to illustrate that binding of a water-soluble meso-tetraarylporphyrin molecule to GAL-7 induces protein oligomerization and modulation of GAL-7-induced apoptosis in human Jurkat T cells. Our results suggest that the integrity of the GAL-7 homodimer architecture is essential for its molecular function, in addition to providing an interesting porphyrin binding modulator for controlling apoptosis in mammalian cells

Des rencontres de proximité : le prendre soin de soi des intervenants au coeur de l’intervention solidaire pour joindre les jeunes en marge. Deuxième partie

Le travail de proximité auprès des jeunes en situation de grande précarité soulève chez les aidants beaucoup d’émotions et d’interrogations tout en les confrontant à leur propre souffrance et à leurs fragilités. Afin de les aider à aider et contrer le risque de traumatisation vicariante, des espaces de parole et des lieux d’échange avec un tiers ont été créés dans divers milieux d’intervention. L’objectif étant de permettre aux intervenants d’élaborer ce que leur travail leur fait vivre, et de préserver ainsi leur équilibre et leur capacité de penser. Par le biais de discussions cliniques de groupe ou individuelles, ces échanges favorisent la prise de distance et autorise de nouvelles perspectives du travail d’intervention. C’est pourquoi le soutien entre pairs est apparu un élément incontournable pour les psychologues et thérapeutes qui soutiennent non seulement les jeunes mais les intervenants qui les aident. La mise sur pied de nos rencontres de proximité, fruit de ce constat, permet de maintenir la flamme sans se brûler. La question de la marginalité des intervenants qui travaillent auprès des jeunes sans domicile fixe — de même que la nôtre — est soulevée. Tantôt par l’absence de lieu fixe de rencontre symbolisant traditionnellement la stabilité, tantôt par la flexibilité requise du cadre d’intervention pour joindre cette population, tantôt par l’ouverture à l’altérité et plus précisément à la différence qui dérange quand elle soulève l’angoisse que cet être désaffilié pourrait bien être soi ! S’agit-il vraiment de marginalité ou d’un positionnement particulier visant une dénonciation constructive de la stigmatisation, de l’exclusion injuste que subissent les jeunes qui présentent des problèmes de santé mentale et de toxicomanie qui les mettent à risque d’itinérance ? Ni missionnaires, ni sauveurs, simplement des accompagnants pleins d’espoir aux côtés d’individus qui veulent se tenir debout et avoir une place dans notre société.Outreach work with youths in a precarious situation raises emotions and questions in workers while confronting them with their own suffering and fragility. In order to help them help as well as counter the risk of vicarious traumatisation, spaces for talking and exchanging with a third party have been created in various intervention settings. The objective is to allow them to elaborate on what their work makes them feel and thus preserve their stability and their ability to think. Through group or individual clinical discussions, these exchanges favor distancing and allow new perspectives on their work. That is why peer support appeared as an essential element for psychologists and therapists who support not only youths but the workers who help them. The setting up of our outreach meetings—a result of our observation, allows keeping the flame alive without risking being burned. In this article, the issue of marginality in professionals working with homeless youths—as well as our own—is raised. It sometimes translates in the absence of a fixed location for a meeting symbolizing traditional stability, sometimes in the necessary flexibility of a framework to reach this population, sometimes in the openness to otherness and more precisely to a difference that disturbs when anxiety that this disaffiliated being raises, could well be our very self! Is it really marginality or a particular positioning aiming at constructive denunciation of stigmatization, unjust exclusion that youths with mental health and addiction problems sustain that place them at risk of homelessness? Neither missionaries, nor saviors are needed, but only hopeful facilitators working alongside people who want to stand up and take their place in society

Perturbing dimer interactions and allosteric communication modulates the immunosuppressive activity of human galectin-7

info:eu-repo/semantics/publishe

Homogeneity in immune features between colorectal liver metastases better identifies patients with good prognosis compared to pathological response to preoperative chemotherapy

ABSTRACTIn colorectal cancer liver metastases (CRLM), the density of tumor-infiltrating lymphocytes, the expression of class I major histocompatibility complex (MHC-I), and the pathological response to preoperative chemotherapy have been associated with oncological outcomes after complete resection. However, the prognostic significance of the heterogeneity of these features in patients with multiple CRLMs remains under investigation. We used a tissue microarray of 220 mismatch repair-gene proficient CRLMs resected in 97 patients followed prospectively to quantify CD3+ T cells and MHC-I by immunohistochemistry. Histopathological response to preoperative chemotherapy was assessed using standard scoring systems. We tested associations between clinical, immunological, and pathological features with oncologic outcomes. Overall, 29 patients (30.2%) had CRLMs homogeneous for CD3+ T cell infiltration and MHC-I. Patients with immune homogeneous compared to heterogeneous CRLMs had longer median time to recurrence (TTR) (30 vs. 12 months, p = .0018) and disease-specific survival (DSS) (not reached vs. 48 months, p = .0009). At 6 years, 80% of the patients with immune homogeneous CRLMs were still alive. Homogeneity of response to preoperative chemotherapy was seen in 60 (61.9%) and 69 (80.2%) patients according to different grading systems and was not associated with TTR or DSS. CD3 and MHC-I heterogeneity was independent of response to pre-operative chemotherapy and of other clinicopathological variables for their association with oncological outcomes. In patients with multiple CRLMs resected with curative intent, similar adaptive immune features seen across metastases could be more informative than pathological response to pre-operative chemotherapy in predicting oncological outcomes