1,695 research outputs found
Three-dimensional charge transport mapping by two-photon absorption edge transient-current technique in synthetic single-crystalline diamond
We demonstrate the application of two-photon absorption transient current
technique to wide bandgap semiconductors. We utilize it to probe charge
transport properties of single-crystal Chemical Vapor Deposition (scCVD)
diamond. The charge carriers, inside the scCVD diamond sample, are excited by a
femtosecond laser through simultaneous absorption of two photons. Due to the
nature of two-photon absorption, the generation of charge carriers is confined
in space (3-D) around the focal point of the laser. Such localized charge
injection allows to probe the charge transport properties of the semiconductor
bulk with a fine-grained 3-D resolution. Exploiting spatial confinement of the
generated charge, the electrical field of the diamond bulk was mapped at
different depths and compared to an X-ray diffraction topograph of the sample.
Measurements utilizing this method provide a unique way of exploring spatial
variations of charge transport properties in transparent wide-bandgap
semiconductors.Comment: This article may be downloaded for personal use only. Any other use
requires prior permission of the author and AIP Publishing. The following
article appeared in Applied Physics Letters and may be found at
https://doi.org/10.1063/1.509085
Signaling from the plasma-membrane localized plant immune receptor RPM1 requires self-association of the full-length protein
Pathogen recognition first occurs at the plasma membrane, where receptor-like kinases perceive pathogen-derived molecules and initiate immune responses. To abrogate this immune response, pathogens evolved effector proteins that act as virulence factors, often following delivery to the host cell. Plants evolved intracellular receptors, known as NOD-like receptors (NLRs), to detect effectors, thereby ensuring activation of effector-triggered immunity. However, despite their importance in immunity, the molecular mechanisms underlying effector recognition and subsequent immune activation by membrane-localized NLRs remain to be fully elucidated. Our analyses reveal the importance of and need for self-association and the coordinated interplay of specific domains and conserved residues for NLR activity. This could provide strategies for crop improvement, contributing to effective, environmentally friendly, and sustainable solutions for future agriculture
TIR-only protein RBA1 recognizes a pathogen effector to regulate cell death in Arabidopsis
Multicellular organisms must have complex immune systems to detect and defeat pathogens. Plants rely on nucleotide binding site leucine rich repeat (NLR) intracellular receptors to detect pathogens. For hundreds of years, plant breeders have selected for disease-resistance traits derived from NLR genes. Despite the molecular cloning of the first NLRs more than 20 y ago, we still do not understand how these sensors function at a mechanistic level. Here, we identified a truncated NLR protein that activates cell death in response to a specific pathogen effector. Understanding how truncated NLRs function will provide a better mechanistic understanding of the plant immune system and an expanded toolkit with which to engineer disease resistance rationally in crops
Measurements of branching fraction ratios and CP-asymmetries in suppressed B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^- decays
We report the first reconstruction in hadron collisions of the suppressed
decays B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^-, sensitive to the
CKM phase gamma, using data from 7 fb^-1 of integrated luminosity collected by
the CDF II detector at the Tevatron collider. We reconstruct a signal for the
B^- -> D(-> K^+ pi^-)K^- suppressed mode with a significance of 3.2 standard
deviations, and measure the ratios of the suppressed to favored branching
fractions R(K) = [22.0 \pm 8.6(stat)\pm 2.6(syst)]\times 10^-3, R^+(K) =
[42.6\pm 13.7(stat)\pm 2.8(syst)]\times 10^-3, R^-(K)= [3.8\pm 10.3(stat)\pm
2.7(syst]\times 10^-3, as well as the direct CP-violating asymmetry A(K) =
-0.82\pm 0.44(stat)\pm 0.09(syst) of this mode. Corresponding quantities for
B^- -> D(-> K^+ pi^-)pi^- decay are also reported.Comment: 8 pages, 1 figure, accepted by Phys.Rev.D Rapid Communications for
Publicatio
Observation of Exclusive Gamma Gamma Production in p pbar Collisions at sqrt{s}=1.96 TeV
We have observed exclusive \gamma\gamma production in proton-antiproton
collisions at \sqrt{s}=1.96 TeV, using data from 1.11 \pm 0.07 fb^{-1}
integrated luminosity taken by the Run II Collider Detector at Fermilab. We
selected events with two electromagnetic showers, each with transverse energy
E_T > 2.5 GeV and pseudorapidity |\eta| < 1.0, with no other particles detected
in -7.4 < \eta < +7.4. The two showers have similar E_T and azimuthal angle
separation \Delta\phi \sim \pi; 34 events have two charged particle tracks,
consistent with the QED process p \bar{p} to p + e^+e^- + \bar{p} by two-photon
exchange, while 43 events have no charged tracks. The number of these events
that are exclusive \pi^0\pi^0 is consistent with zero and is < 15 at 95% C.L.
The cross section for p\bar{p} to p+\gamma\gamma+\bar{p} with |\eta(\gamma)| <
1.0 and E_T(\gamma) > 2.5$ GeV is
2.48^{+0.40}_{-0.35}(stat)^{+0.40}_{-0.51}(syst) pb.Comment: 7 pages, 4 figure
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