61 research outputs found
Angle-resolved cathodoluminescence imaging polarimetry
Cathodoluminescence spectroscopy (CL) allows characterizing light emission in
bulk and nanostructured materials and is a key tool in fields ranging from
materials science to nanophotonics. Previously, CL measurements focused on the
spectral content and angular distribution of emission, while the polarization
was not fully determined. Here we demonstrate a technique to access the full
polarization state of the cathodoluminescence emission, that is the Stokes
parameters as a function of the emission angle. Using this technique, we
measure the emission of metallic bullseye nanostructures and show that the
handedness of the structure as well as nanoscale changes in excitation position
induce large changes in polarization ellipticity and helicity. Furthermore, by
exploiting the ability of polarimetry to distinguish polarized from unpolarized
light, we quantify the contributions of different types of coherent and
incoherent radiation to the emission of a gold surface, silicon and gallium
arsenide bulk semiconductors. This technique paves the way for in-depth
analysis of the emission mechanisms of nanostructured devices as well as
macroscopic media.Comment: 8 figures. Includes supplementary informatio
Spatial entanglement of paired photons generated in cold atomic ensembles
Cold atomic ensembles can mediate the generation of entanglement between
pairs of photons. Photons with specific directions of propagation are detected,
and the entanglement can reside in any of the degrees of freedom that describe
the whole quantum state of the photons: polarization, spatial shape or
frequency. We show that the direction of propagation of the generated photons
determines the spatial quantum state of the photons and therefore, the amount
of entanglement generated. When photons generated in different directions are
combined, this spatial distinguishing information can degrade the quantum
purity of the polarization or frequency entanglement.Comment: 5 pages, 4 figures. Submitted to Phys. Rev. A.; one figure (Fig. 3)
was added, typos and labels in figure 2 were correcte
Backaction in metasurface etalons
We consider the response of etalons created by a combination of a
conventional mirror and a metasurface, composed of a periodic lattice of metal
scatterers with a resonant response. This geometry has been used previously for
perfect absorption, in so-called Salisbury screens, and for hybridization of
localized plasmons with Fabry-Perot resonances. The particular aspect we
address is if one can assume an environment-independent reflectivity for the
metasurface when calculating the reflectivity of the composite system, as in a
standard Fabry-Perot analysis, or whether the fact that the metasurface
interacts with its own mirror image renormalizes its response. Using lattice
sum theory, we take into account all possible retarded dipole-dipole
interactions of scatterers in the metasurface amongst each other, and through
the mirror. We show that while a layer-by-layer Fabry-Perot formalism captures
the main qualitative features of metasurface etalons, in fact the mirror
modifies both the polarizability and reflectivity of the metasurface in a
fashion that is akin to Drexhage's modification of the radiative properties of
a single dipole.Comment: 10 pages, 5 figure
Shape of the spatial mode function of photons generated in noncollinear spontaneous parametric downconversion
We show experimentally how noncollinear geometries in spontaneous parametric
downconversion induce ellipticity of the shape of the spatial mode function.
The degree of ellipticity depends on the pump beam width, especially for highly
focused beams. We also discuss the ellipticity induced by the spectrum of the
pump beam
Correlations in orbital angular momentum of spatially entangled paired photons generated in parametric downconversion
What are the orbital angular momentum correlations between spatially
entangled photon pairs generated in spontaneous parametric down-conversion? We
show that the answer to this question can be given in two alternative, although
complementary, ways. The answer posed in this letter explains satisfactorily
the seemingly contradictory results obtained in different experiments, and
theoretical approaches.Comment: 4 pages, 3 figures. Submitted to PR
Azimuthal distinguishability of entangled photons generated in spontaneous parametric down-conversion
We experimentally demonstrate that paired photons generated in different
sections of a down-conversion cone, when some of the interacting waves show
Poynting vector walk-off, carry different spatial correlations, and therefore a
different degree of spatial entanglement. This is shown to be in agreement with
theoretical results. We also discuss how this azimuthal distinguishing
information of the down-conversion cone is relevant for the implementation of
quantum sources aimed at the generation of entanglement in other degrees of
freedom, such as polarization.Comment: 7 pages, 5 figures, submitted to Opt. Expres
A Collaborative Effort to Define Classification Criteria for ATM Variants in Hereditary Cancer Patients
Background
Gene panel testing by massive parallel sequencing has increased the diagnostic yield but also the number of variants of uncertain significance. Clinical interpretation of genomic data requires expertise for each gene and disease. Heterozygous ATM pathogenic variants increase the risk of cancer, particularly breast cancer. For this reason, ATM is included in most hereditary cancer panels. It is a large gene, showing a high number of variants, most of them of uncertain significance. Hence, we initiated a collaborative effort to improve and standardize variant classification for the ATM gene.
Methods
Six independent laboratories collected information from 766 ATM variant carriers harboring 283 different variants. Data were submitted in a consensus template form, variant nomenclature and clinical information were curated, and monthly team conferences were established to review and adapt American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) criteria to ATM, which were used to classify 50 representative variants.
Results
Amid 283 different variants, 99 appeared more than once, 35 had differences in classification among laboratories. Refinement of ACMG/AMP criteria to ATM involved specification for twenty-one criteria and adjustment of strength for fourteen others. Afterwards, 50 variants carried by 254 index cases were classified with the established framework resulting in a consensus classification for all of them and a reduction in the number of variants of uncertain significance from 58% to 42%.
Conclusions
Our results highlight the relevance of data sharing and data curation by multidisciplinary experts to achieve improved variant classification that will eventually improve clinical management.FEDER funds-a way to build Europe
PI19/00553
PI16/00563
PI16/01898
SAF2015-68016-RGeneralitat de Catalunya
2017SGR1282
2017SGR496CERCA Program: Government of CataloniaXunta de GaliciaInstituto de Salud Carlos III. AES
PI19/00340Spanish Government
SAF2016-80255-REuropean Commission
EFA086/15Instituto de Salud Carlos III
European Commissio
Identification of 12 new susceptibility loci for different histotypes of epithelial ovarian cancer.
To identify common alleles associated with different histotypes of epithelial ovarian cancer (EOC), we pooled data from multiple genome-wide genotyping projects totaling 25,509 EOC cases and 40,941 controls. We identified nine new susceptibility loci for different EOC histotypes: six for serous EOC histotypes (3q28, 4q32.3, 8q21.11, 10q24.33, 18q11.2 and 22q12.1), two for mucinous EOC (3q22.3 and 9q31.1) and one for endometrioid EOC (5q12.3). We then performed meta-analysis on the results for high-grade serous ovarian cancer with the results from analysis of 31,448 BRCA1 and BRCA2 mutation carriers, including 3,887 mutation carriers with EOC. This identified three additional susceptibility loci at 2q13, 8q24.1 and 12q24.31. Integrated analyses of genes and regulatory biofeatures at each locus predicted candidate susceptibility genes, including OBFC1, a new candidate susceptibility gene for low-grade and borderline serous EOC
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