119 research outputs found
Electric-field control of the magnetic anisotropy in an ultrathin (Ga,Mn)As/(Ga,Mn)(As,P) bilayer
We report on the electric control of the magnetic anisotropy in an ultrathin
ferromagnetic (Ga,Mn)As/(Ga,Mn)(As,P) bilayer with competing in-plane and
out-of-plane anisotropies. The carrier distribution and therefore the strength
of the effective anisotropy is controlled by the gate voltage of a field effect
device. Anomalous Hall Effect measurements confirm that a depletion of carriers
in the upper (Ga,Mn)As layer results in the decrease of the in-plane
anisotropy. The uniaxial anisotropy field is found to decrease by a factor ~ 4
over the explored gate-voltage range, so that the transition to an out-of-plane
easy-axis configuration is almost reached
Universal pinning energy barrier for driven domain walls in thin ferromagnetic films
We report a comparative study of magnetic field driven domain wall motion in
thin films made of different magnetic materials for a wide range of field and
temperature. The full thermally activated creep motion, observed below the
depinning threshold, is shown to be described by a unique universal energy
barrier function. Our findings should be relevant for other systems whose
dynamics can be modeled by elastic interfaces moving on disordered energy
landscapes.Comment: 10 pages, 3 figure
Effect of picosecond strain pulses on thin layers of the ferromagnetic semiconductor (Ga,Mn)(As,P)
The effect of picosecond acoustic strain pulses (ps-ASP) on a thin layer of
(Ga,Mn)As co-doped with phosphorus was probed using magneto-optical Kerr effect
(MOKE). A transient MOKE signal followed by low amplitude oscillations was
evidenced, with a strong dependence on applied magnetic field, temperature and
ps-ASP amplitude. Careful interferometric measurement of the layer's thickness
variation induced by the ps-ASP allowed us to model very accurately the
resulting signal, and interpret it as the strain modulated reflectivity
(differing for probe polarizations), independently from dynamic
magnetization effects.Comment: 6 pages, 5 figure
The genetic architecture of language functional connectivity
Available online 18 December 2021Language is a unique trait of the human species, of which the genetic architecture remains largely unknown. Through language disorders studies, many candidate genes were identified. However, such complex and multi- factorial trait is unlikely to be driven by only few genes and case-control studies, suffering from a lack of power, struggle to uncover significant variants. In parallel, neuroimaging has significantly contributed to the under- standing of structural and functional aspects of language in the human brain and the recent availability of large scale cohorts like UK Biobank have made possible to study language via image-derived endophenotypes in the general population. Because of its strong relationship with task-based fMRI (tbfMRI) activations and its easiness of acquisition, resting-state functional MRI (rsfMRI) have been more popularised, making it a good surrogate of functional neuronal processes. Taking advantage of such a synergistic system by aggregating effects across spa- tially distributed traits, we performed a multivariate genome-wide association study (mvGWAS) between genetic variations and resting-state functional connectivity (FC) of classical brain language areas in the inferior frontal (pars opercularis, triangularis and orbitalis), temporal and inferior parietal lobes (angular and supramarginal gyri), in 32,186 participants from UK Biobank. Twenty genomic loci were found associated with language FCs, out of which three were replicated in an independent replication sample. A locus in 3p11.1, regulating EPHA3 gene expression, is found associated with FCs of the semantic component of the language network, while a lo- cus in 15q14, regulating THBS1 gene expression is found associated with FCs of the perceptual-motor language processing, bringing novel insights into the neurobiology of language.This research was conducted using the UK Biobank resource un- der application #64984. This project was supported by the Marie Sklodowska-Curie program awarded to Stephanie J. Forkel (Grant agree- ment No. 101028551). Amaia Carrion-Castillo was supported by a Juan de la Cierva fellowship from the Spanish Ministry of Science and Innova- tion, and a Gipuzkoa Fellows fellowship from the Basque Governmen
MoMEMta, a modular toolkit for the Matrix Element Method at the LHC
The Matrix Element Method has proven to be a powerful method to optimally
exploit the information available in detector data. Its widespread use is
nevertheless impeded by its complexity and the associated computing time.
MoMEMta, a C++ software package to compute the integrals at the core of the
method, provides a versatile implementation of the Matrix Element Method to
both the theory and experiment communities. Its modular structure covers the
needs of experimental analysis workflows at the LHC without compromising ease
of use on simpler and smaller simulated samples used for phenomenological
studies. With respect to existing tools, MoMEMta improves on usability and
flexibility. In this paper, we present version 1.0 of MoMEMta, together with
examples illustrating the wide range of applications at the LHC accessible for
the first time with a single tool.Comment: 18 pages, 3 figures; post peer revie
Wood fiber orientation assessment based on punctual laser beam excitation: A preliminary study
International audienceThe EU imposes standards for the use of wood in structural applications. Local singularities such as knots affect the wood mechanical properties. They can be revealed by looking at the wood fiber orientation. For this reason, many methods were proposed to estimate the orientation of wood fiber using optical means, X-rays, or scattering measurement techniques. In this paper, an approach to assess the wood fiber orientation based on thermal ellipsometry is developed. The wood part is punctually heated with a Nd-YAG Laser and the thermal response is acquired by an infrared camera. The thermal response is elliptical due to the propagation of the heat through and along the wood fibers. An experiment is presented to show the capacity of such techniques to assess fiber orientation on wood specimen. In addition, an appropriate algorithm is given to extract the orientation of the ellipse
Strain-Control of the magnetic anisotropy in (Ga,Mn)(As,P) ferromagnetic semiconductor layers
A small fraction of phosphorus (up to 10 %) was incorporated in ferromagnetic
(Ga,Mn)As epilayers grown on a GaAs substrate. P incorporation allows reducing
the epitaxial strain or even change its sign, resulting in strong modifications
of the magnetic anisotropy. In particular a reorientation of the easy axis
toward the growth direction is observed for high P concentration. It offers an
interesting alternative to the metamorphic approach, in particular for
magnetization reversal experiments where epitaxial defects stongly affect the
domain wall propagation
Nuclear position dictates DNA repair pathway choice
Faithful DNA repair is essential to avoid chromosomal rearrangements and promote genome integrity. Nuclear organization has emerged as a key parameter in the formation of chromosomal translocations, yet little is known as to whether DNA repair can efficiently occur throughout the nucleus and whether it is affected by the location of the lesion. Here, we induce DNA double-strand breaks (DSBs) at different nuclear compartments and follow their fate. We demonstrate that DSBs induced at the nuclear membrane (but not at nuclear pores or nuclear interior) fail to rapidly activate the DNA damage response (DDR) and repair by homologous recombination (HR). Real-time and superresolution imaging reveal that DNA DSBs within lamina-associated domains do not migrate to more permissive environments for HR, like the nuclear pores or the nuclear interior, but instead are repaired in situ by alternative end-joining. Our results are consistent with a model in which nuclear position dictates the choice of DNA repair pathway, thus revealing a new level of regulation in DSB repair controlled by spatial organization of DNA within the nucleus
Evf, a virulence factor produced by the Drosophila pathogen Erwinia carotovora, is an S-palmitoylated protein with a new fold that binds to lipid vesicles
Erwinia carotovora are phytopathogenic Gram-negative bacteria of agronomic interest as these bacteria are responsible for fruit soft rot and use insects as dissemination vectors. The Erwinia carotovora carotovora strain 15 (Ecc15) is capable of persisting in the Drosophila gut by the sole action of one protein, Erwinia virulence factor (Evf). However, the precise function of Evf is elusive, and its sequence does not provide any indication as to its biochemical function. We have solved the 2.0-angstroms crystal structure of Evf and found a protein with a complex topology and a novel fold. The structure of Evf confirms that Evf is unlike any virulence factors known to date. Most remarkably, we identified palmitoic acid covalently bound to the totally conserved Cys209, which provides important clues as to the function of Evf. Mutation of the palmitoic binding cysteine leads to a loss of virulence, proving that palmitoylation is at the heart of Evf infectivity and may be a membrane anchoring signal. Fluorescence studies of the sole tryptophan residue (Trp94) demonstrated that Evf was indeed able to bind to model membranes containing negatively charged phospholipids and to promote their aggregation
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