466 research outputs found
Histaminylation of glutamine residues is a novel posttranslational modification implicated in G-protein signaling
Posttranslational modifications (PTM) have been shown to be essential for protein function and signaling. Here we report the identification of a novel modification, protein transfer of histamine, and provide evidence for its function in G protein signaling. Histamine, known as neurotransmitter and mediator of the inflammatory response, was found incorporated into mastocytoma proteins. Histaminylation was dependent on transglutaminase II. Mass spectrometry confirmed histamine modification of the small and heterotrimeric G proteins Cdc42, Galphao1 and Galphaq. The modification was specific for glutamine residues in the catalytic core, and triggered their constitutive activation. TGM2-mediated histaminylation is thus a novel PTM that functions in G protein signaling. Protein alphamonoaminylations, thus including histaminylation, serotonylation, dopaminylation and norepinephrinylation, hence emerge as a novel class of regulatory PTMs
Product assurance technology for custom LSI/VLSI electronics
The technology for obtaining custom integrated circuits from CMOS-bulk silicon foundries using a universal set of layout rules is presented. The technical efforts were guided by the requirement to develop a 3 micron CMOS test chip for the Combined Release and Radiation Effects Satellite (CRRES). This chip contains both analog and digital circuits. The development employed all the elements required to obtain custom circuits from silicon foundries, including circuit design, foundry interfacing, circuit test, and circuit qualification
Limits on Dark Matter Effective Field Theory Parameters with CRESST-II
CRESST is a direct dark matter search experiment, aiming for an observation
of nuclear recoils induced by the interaction of dark matter particles with
cryogenic scintillating calcium tungstate crystals. Instead of confining
ourselves to standard spin-independent and spin-dependent searches, we
re-analyze data from CRESST-II using a more general effective field theory
(EFT) framework. On many of the EFT coupling constants, improved exclusion
limits in the low-mass region (< 3-4 GeV) are presented.Comment: 7 pages, 9 figure
Results on MeV-scale dark matter from a gram-scale cryogenic calorimeter operated above ground
Models for light dark matter particles with masses below 1 GeV/c are a
natural and well-motivated alternative to so-far unobserved weakly interacting
massive particles. Gram-scale cryogenic calorimeters provide the required
detector performance to detect these particles and extend the direct dark
matter search program of CRESST. A prototype 0.5 g sapphire detector developed
for the -cleus experiment has achieved an energy threshold of
eV, which is one order of magnitude lower than previous
results and independent of the type of particle interaction. The result
presented here is obtained in a setup above ground without significant
shielding against ambient and cosmogenic radiation. Although operated in a
high-background environment, the detector probes a new range of light-mass dark
matter particles previously not accessible by direct searches. We report the
first limit on the spin-independent dark matter particle-nucleon cross section
for masses between 140 MeV/c and 500 MeV/c.Comment: 6 pages, 6 figures, v3: ancillary files added, v4: high energy
spectrum (0.6-12keV) added to ancillary file
First results from the CRESST-III low-mass dark matter program
The CRESST experiment is a direct dark matter search which aims to measure
interactions of potential dark matter particles in an earth-bound detector.
With the current stage, CRESST-III, we focus on a low energy threshold for
increased sensitivity towards light dark matter particles. In this manuscript
we describe the analysis of one detector operated in the first run of
CRESST-III (05/2016-02/2018) achieving a nuclear recoil threshold of 30.1eV.
This result was obtained with a 23.6g CaWO crystal operated as a cryogenic
scintillating calorimeter in the CRESST setup at the Laboratori Nazionali del
Gran Sasso (LNGS). Both the primary phonon/heat signal and the simultaneously
emitted scintillation light, which is absorbed in a separate
silicon-on-sapphire light absorber, are measured with highly sensitive
transition edge sensors operated at ~15mK. The unique combination of these
sensors with the light element oxygen present in our target yields sensitivity
to dark matter particle masses as low as 160MeV/c.Comment: 9 pages, 9 figure
COSINUS: Cryogenic Calorimeters for the Direct Dark Matter Search with NaI Crystals
COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) is an experiment employing cryogenic calorimeters, dedicated to direct dark matter search in underground laboratories. Its goal is to cross-check the annual modulation signal the DAMA collaboration has been detecting for about 20 years (Bernabei et al. in Nucl Part Phys Proc 303-305:74-79, 2018. 10.1016/j.nuclphysbps.2019.03.015) and which has been ruled out by other experiments in certain dark matter scenarios. COSINUS can provide a model-independent test by the use of the same target material (NaI), with the additional chance of discriminating beta/gamma events from nuclear recoils on an event-by-event basis, by the application of a well-established temperature sensor technology developed within the CRESST collaboration. Each module is constituted by two detectors: the light detector, that is a silicon beaker equipped with a transition edge sensor (TES), and the phonon detector, a small cubic NaI crystal interfaced with a carrier of a harder material (e.g. CdWO4), also instrumented with a TES. This technology had so far never been applied to NaI crystals because of several well-known obstacles, and COSINUS is the first experiment which succeeded in operating NaI crystals as cryogenic calorimeters. Here, we present the COSINUS project, describe the achievements and the challenges of the COSINUS prototype development and discuss the status and the perspectives of this NaI-based cryogenic frontier
Resonant nonlinear magneto-optical effects in atoms
In this article, we review the history, current status, physical mechanisms,
experimental methods, and applications of nonlinear magneto-optical effects in
atomic vapors. We begin by describing the pioneering work of Macaluso and
Corbino over a century ago on linear magneto-optical effects (in which the
properties of the medium do not depend on the light power) in the vicinity of
atomic resonances, and contrast these effects with various nonlinear
magneto-optical phenomena that have been studied both theoretically and
experimentally since the late 1960s. In recent years, the field of nonlinear
magneto-optics has experienced a revival of interest that has led to a number
of developments, including the observation of ultra-narrow (1-Hz)
magneto-optical resonances, applications in sensitive magnetometry, nonlinear
magneto-optical tomography, and the possibility of a search for parity- and
time-reversal-invariance violation in atoms.Comment: 51 pages, 23 figures, to appear in Rev. Mod. Phys. in Oct. 2002,
Figure added, typos corrected, text edited for clarit
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