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ERCC1‐XPF endonuclease-positioned to cut
Schä,rer, Orlando D EMBO 2017 The EMBO journal Vol.36 No.14
<P>To counteract damage to our genomes, numerous endo-and exonucleases incise the DNA backbone to remove damaged and aberrant DNA structures. It is imperative that such incisions be very tightly controlled, as unwanted DNA breaks are a key source of genome instability. Two new papers in The EMBO Journal shed light on how the activity of one such nuclease-ERCC1-XPF, an enzyme involved in various DNA repair pathways-is regulated to perform incision in the vicinity of DNA interstrand crosslinks.</P>
Exclusive photoproduction of <i>φ</i> meson in γp→φp and pp→pφp reactions
Cisek, A.,Schä,fer, W.,Szczurek, A. Elsevier 2010 Physics letters: B Vol.690 No.2
<P><B>Abstract</B></P><P>The amplitude for γp→φp is calculated in a pQCD <SUB>kT</SUB>-factorization approach. The total cross section for this process is compared with HERA data. Total cross section, as a function of photon–proton energy and photon virtuality, is calculated. We also discuss the ratio of <SUB>σL</SUB>/<SUB>σT</SUB> and the dependence on the mass of the strange quark. The amplitude for γp→φp is used to predict the cross section for exclusive photoproduction of <I>φ</I> meson in proton–proton collisions. Absorption effects are included. The results for RHIC, Tevatron and LHC energies are presented.</P>
Kurz, Angela R. M.,Pruenster, Monika,Rohwedder, Ina,Ramadass, Mahalakshmi,Schä,fer, Kerstin,Harrison, Ute,Gouveia, Gabriel,Nussbaum, Claudia,Immler, Roland,Wiessner, Johannes R. American Society for Clinical Investigation 2016 The Journal of clinical investigation Vol.126 No.11
<P>Neutrophils need to penetrate the perivascular basement membrane for successful extravasation into inflamed tissue, but this process is incompletely understood. Recent findings have associated mammalian sterile 20-like Kinase 1 (MST1) loss of function with a human primary immunodeficiency disorder, suggesting that MST1 may be involved in immune cell migration. Here, we have shown that MST1 is a critical regulator of neutrophil extravasation during inflammation. Mst1-deficient (Mst1(-/-)) neutrophils were unable to migrate into inflamed murine cremaster muscle venules, instead persisting between the endothelium and the basement membrane. Mst1(-/-) neutrophils also failed to extravasate from gastric submucosal vessels in a murine model of Helicobacter pylori infection. Mechanistically, we observed defective translocation of VLA-3, VLA-6, and neutrophil elastase from intracellular vesicles to the surface of Mst1(-/-) neutrophils, indicating that MST1 is required for this crucial step in neutrophil transmigration. Furthermore, we found that MST1 associates with the Rab27 effector protein synaptotagmin-like protein 1 (JFC1, encoded by Sytl1 in mice), but not Munc13-4, thereby regulating the trafficking of Rab27-positive vesicles to the cellular membrane. Together, these findings highlight a role for MST1 in vesicle trafficking and extravasation in neutrophils, providing an additional mechanistic explanation for the severe immune defect observed in patients with MST1 deficiency.</P>
Objective quality assessment of stereoscopic images with vertical disparity using EEG
Avarvand, Forooz Shahbazi,Bosse, Sebastian,Mü,ller, Klaus-Robert,Schä,fer, Ralf,Nolte, Guido,Wiegand, Thomas,Curio, Gabriel,Samek, Wojciech IOP 2017 Journal of neural engineering Vol.14 No.4
<P> <I>Objective</I>. Neurophysiological correlates of vertical disparity in 3D images are studied in an objective approach using EEG technique. These disparities are known to negatively affect the quality of experience and to cause visual discomfort in stereoscopic visualizations. <I>Approach</I>. We have presented four conditions to subjects: one in 2D and three conditions in 3D, one without vertical disparity and two with different vertical disparity levels. Event related potentials (ERPs) are measured for each condition and the differences between ERP components are studied. Analysis is also performed on the induced potentials in the time frequency domain. <I>Main results</I>. Results show that there is a significant increase in the amplitude of P1 components in 3D conditions in comparison to 2D. These results are consistent with previous studies which have shown that P1 amplitude increases due to the depth perception in 3D compared to 2D. However the amplitude is significantly smaller for maximum vertical disparity (3D-3) in comparison to 3D with no vertical disparity. Our results therefore suggest that the vertical disparity in 3D-3 condition decreases the perception of depth compared to other 3D conditions and the amplitude of P1 component can be used as a discriminative feature. <I>Significance</I>. The results show that the P1 component increases in amplitude due to the depth perception in the 3D stimuli compared to the 2D stimulus. On the other hand the vertical disparity in the stereoscopic images is studied here. We suggest that the amplitude of P1 component is modulated with this parameter and decreases due to the decrease in the perception of depth.</P>
Faraday-Shielded dc Stark-Shift-Free Optical Lattice Clock
Beloy, K.,Zhang, X.,McGrew, W. F.,Hinkley, N.,Yoon, T. H.,Nicolodi, D.,Fasano, R. J.,Schä,ffer, S. A.,Brown, R. C.,Ludlow, A. D. American Physical Society 2018 Physical Review Letters Vol.120 No.18
<P>We demonstrate the absence of a dc Stark shift in an ytterbium optical lattice clock. Stray electric fields are suppressed through the introduction of an in-vacuum Faraday shield. Still, the effectiveness of the shielding must be experimentally assessed. Such diagnostics are accomplished by applying high voltage to six electrodes, which are grounded in normal operation to form part of the Faraday shield. Our measurements place a constraint on the dc Stark shift at the 10(-20) level, in units of the clock frequency. Moreover, we discuss a potential source of error in strategies to precisely measure or cancel nonzero dc Stark shifts, attributed to field gradients coupled with the finite spatial extent of the lattice-trapped atoms. With this consideration, we find that Faraday shielding, complemented with experimental validation, provides both a practically appealing and effective solution to the problem of dc Stark shifts in optical lattice clocks.</P>