Université Paris-Saclay

About: Université Paris-Saclay is a education organization based out in Gif-sur-Yvette, France. It is known for research contribution in the topics: Population & Context (language use). The organization has 29307 authors who have published 43183 publications receiving 867404 citations.

Femtosecond Single-Shot Imaging of Nanoscale Ferromagnetic Order in Co=Pd Multilayers Using Resonant X-Ray Holography

Abstract: We present the first single-shot images of ferromagnetic, nanoscale spin order taken with femtosecond x-ray pulses. X-ray-induced electron and spin dynamics can be outrun with pulses shorter than 80 fs in the investigated fluence regime, and no permanent aftereffects in the samples are observed below a fluence of 25 mJ/cm{sup 2}. Employing resonant spatially-muliplexed x-ray holography results in a low imaging threshold of 5 mJ/cm{sup 2}. Our results open new ways to combine ultrafast laser spectroscopy with sequential snapshot imaging on a single sample, generating a movie of excited state dynamics.

A Review of Sparse Recovery Algorithms

Abstract: Nowadays, a large amount of information has to be transmitted or processed. This implies high-power processing, large memory density, and increased energy consumption. In several applications, such as imaging, radar, speech recognition, and data acquisition, the signals involved can be considered sparse or compressive in some domain. The compressive sensing theory could be a proper candidate to deal with these constraints. It can be used to recover sparse or compressive signals with fewer measurements than the traditional methods. Two problems must be addressed by compressive sensing theory: design of the measurement matrix and development of an efficient sparse recovery algorithm. These algorithms are usually classified into three categories: convex relaxation, non-convex optimization techniques, and greedy algorithms. This paper intends to supply a comprehensive study and a state-of-the-art review of these algorithms to researchers who wish to develop and use them. Moreover, a wide range of compressive sensing theory applications is summarized and some open research challenges are presented.

Are microtubules tension sensors

Abstract: Mechanical signals play many roles in cell and developmental biology. Several mechanotransduction pathways have been uncovered, but the mechanisms identified so far only address the perception of stress intensity. Mechanical stresses are tensorial in nature, and thus provide dual mechanical information: stress magnitude and direction. Here we propose a parsimonious mechanism for the perception of the principal stress direction. In vitro experiments show that microtubules are stabilized under tension. Based on these results, we explore the possibility that such microtubule stabilization operates in vivo, most notably in plant cells where turgor-driven tensile stresses exceed greatly those observed in animal cells.

Progenitors from the central nervous system drive neurogenesis in cancer

Abstract: Autonomic nerve fibres in the tumour microenvironment regulate cancer initiation and dissemination, but how nerves emerge in tumours is currently unknown. Here we show that neural progenitors from the central nervous system that express doublecortin (DCX+) infiltrate prostate tumours and metastases, in which they initiate neurogenesis. In mouse models of prostate cancer, oscillations of DCX+ neural progenitors in the subventricular zone—a neurogenic area of the central nervous system—are associated with disruption of the blood–brain barrier, and with the egress of DCX+ cells into the circulation. These cells then infiltrate and reside in the tumour, and can generate new adrenergic neurons. Selective genetic depletion of DCX+ cells inhibits the early phases of tumour development in our mouse models of prostate cancer, whereas transplantation of DCX+ neural progenitors promotes tumour growth and metastasis. In humans, the density of DCX+ neural progenitors is strongly associated with the aggressiveness and recurrence of prostate adenocarcinoma. These results reveal a unique crosstalk between the central nervous system and prostate tumours, and indicate neural targets for the treatment of cancer. In a mouse model of prostate cancer, neural progenitors from the central nervous system that express doublecortin infiltrate tumours and metastases, and can generate new adrenergic neurons in tumours.