A search for nonresonant Higgs boson pair production in the Formula Presented final state is presented. The analysis uses Formula Presented of Formula Presented collision data at Formula Presented ...collected with the ATLAS detector at the Large Hadron Collider, and targets both the gluon-gluon fusion and vector-boson fusion production modes. No evidence of the signal is found and the observed (expected) upper limit on the cross section for nonresonant Higgs boson pair production is determined to be 5.4 (8.1) times the Standard Model predicted cross section at 95% confidence level. Constraints are placed on modifiers to the Formula Presented and Formula Presented couplings. The observed (expected) Formula Presented constraints on the Formula Presented coupling modifier, Formula Presented, are determined to be Formula Presented (Formula Presented), while the corresponding constraints for the Formula Presented coupling modifier, Formula Presented, are Formula Presented (Formula Presented). In addition, constraints on relevant coefficients are derived in the context of the Standard Model effective field theory and Higgs effective field theory, and upper limits on the Formula Presented production cross section are placed in seven Higgs effective field theory benchmark scenarios.
VUV pressure-broadening in sulfur dioxide Lyons, J.R.; Herde, H.; Stark, G. ...
Journal of quantitative spectroscopy & radiative transfer,
20/May , Letnik:
210
Journal Article
Recenzirano
•Pressure broadening is measured for SO2 at 215 nm for N2 and CO2 bath gases.•Pressure broadening is greater at 215 nm versus 308 nm and 7.4 µm.•Pressure broadening explains isotope effects seen in ...SO2 photolysis experiments.•Pressure broadening in SO2 diminished isotope effects in the early Earth atmosphere.
In the pre-oxygenated ancient Earth atmosphere, the lack of O3 absorption allowed ultraviolet photodissociation of numerous molecules in the troposphere and lower stratosphere. For molecules with narrow line-type absorption spectra, optically thick columns would have produced isotope fractionation due to self-shielding of the most abundant isotopologues. In the lower atmosphere pressure broadening would modify, and in some cases, eliminate these isotope signatures. Shielding is particularly important for quantifying or constraining photolysis-derived isotope effects, such as those believed to explain the sulfur mass-independent fractionation in Archean sedimentary rocks. Here, we report pressure broadening coefficients for natural abundance SO2 in theC˜1B2←X˜1A1band system at 215 nm. For gas bath pressures up to 750 mbar, we find broadening coefficients of 0.30 ± 0.03 cm−1 atm−1 and 0.40 ± 0.04 cm−1 atm−1 for N2 and CO2, respectively. These broadening coefficients are ∼30% larger than SO2 broadening coefficients previously measured in the B˜−X˜ bands at 308 nm. Because of the highly congested nature of the C˜−X˜ bands, pressure broadening in the early Earth troposphere will cause line profile overlap that will diminish the self-shielding-derived mass-independent isotope fractionation for optically thick SO2 columns. Thus, non-explosive volcanic eruptions may not have left a signature of SO2 self-shielding in the ancient sedimentary rock record.
At the end of Run 3 of the Large Hadron Collider (LHC), the accelerator complex will be upgraded to the High-Luminosity LHC (HL-LHC) in order to increase the total amount of data provided to its ...experiments. To cope with the increased rates of data, radiation, and pileup, the ATLAS detector will undergo a substantial upgrade, including a replacement of the Inner Detector with a future Inner Tracker, called the ITk. The ITk will be composed of pixel and strip sub-detectors, where the strips portion will be composed of 17,888 silicon strip detector modules. During the HL-LHC running period, the ITk will be cooled and warmed a number of times from about \({-35}^\circ\)C to room temperature as part of the operational cycle, including warm-ups during yearly shutdowns. To ensure ITk Strips modules are functional after these expected temperature changes, and to ensure modules are mechanically robust, each module must undergo ten thermal cycles and pass a set of electrical and mechanical criteria before it is placed on a local support structure. This paper describes the thermal cycling Quality Control (QC) procedure, and results from the barrel pre-production phase (about 5% of the production volume). Additionally, in order to assess the headroom of the nominal QC procedure of 10 cycles and to ensure modules don't begin failing soon after, four representative ITk Strips barrel modules were thermally cycled 100 times - this study is also described.
Extrasynaptic actions of glutamate are limited by high-affinity transporters expressed by perisynaptic astroglial processes (PAPs): this helps maintain point-to-point transmission in excitatory ...circuits. Memory formation in the brain is associated with synaptic remodeling, but how this affects PAPs and therefore extrasynaptic glutamate actions is poorly understood. Here, we used advanced imaging methods, in situ and in vivo, to find that a classical synaptic memory mechanism, long-term potentiation (LTP), triggers withdrawal of PAPs from potentiated synapses. Optical glutamate sensors combined with patch-clamp and 3D molecular localization reveal that LTP induction thus prompts spatial retreat of astroglial glutamate transporters, boosting glutamate spillover and NMDA-receptor-mediated inter-synaptic cross-talk. The LTP-triggered PAP withdrawal involves NKCC1 transporters and the actin-controlling protein cofilin but does not depend on major Ca2+-dependent cascades in astrocytes. We have therefore uncovered a mechanism by which a memory trace at one synapse could alter signal handling by multiple neighboring connections.
•Induction of synaptic LTP prompts withdrawal of perisynaptic astroglia•The underlying mechanisms involve NKCC1 transporter and cofilin•Reduced synaptic astroglial coverage boosts extrasynaptic glutamate escape•LTP induction thus enhances NMDAR-dependent inter-synaptic cross-talk
Central synapses are often surrounded by thin astroglial processes that confine chemical neurotransmission to the synaptic cleft. Henneberger et al. find that memory trace formation at synaptic connections prompts withdrawal of these processes, thus boosting extrasynaptic neurotransmitter actions. Such actions can alter signal integration rules among neighboring synapses.
The necessity and functional significance of neurotransmitter co-transmission remains unclear. The glutamatergic 'KNDy' neurons co-express kisspeptin, neurokinin B (NKB), and dynorphin and exhibit a ...highly stereotyped synchronized behavior that reads out to the gonadotropin-releasing hormone (GnRH) neuron dendrons to drive episodic hormone secretion. Using expansion microscopy, we show that KNDy neurons make abundant close, non-synaptic appositions with the GnRH neuron dendron. Electrophysiology and confocal GCaMP6 imaging demonstrated that, despite all three neuropeptides being released from KNDy terminals, only kisspeptin was able to activate the GnRH neuron dendron. Mice with a selective deletion of kisspeptin from KNDy neurons failed to exhibit pulsatile hormone secretion but maintained synchronized episodic KNDy neuron behavior that is thought to depend on recurrent NKB and dynorphin transmission. This indicates that KNDy neurons drive episodic hormone secretion through highly redundant neuropeptide co-transmission orchestrated by differential post-synaptic neuropeptide receptor expression at the GnRH neuron dendron and KNDy neuron.
Biosensors for signaling molecules allow the study of physiological processes by bringing together the fields of protein engineering, fluorescence imaging, and cell biology. Construction of ...genetically encoded biosensors generally relies on the availability of a binding “core” that is both specific and stable, which can then be combined with fluorescent molecules to create a sensor. However, binding proteins with the desired properties are often not available in nature and substantial improvement to sensors can be required, particularly with regard to their durability. Ancestral protein reconstruction is a powerful protein‐engineering tool able to generate highly stable and functional proteins. In this work, we sought to establish the utility of ancestral protein reconstruction to biosensor development, beginning with the construction of an l‐arginine biosensor. l‐arginine, as the immediate precursor to nitric oxide, is an important molecule in many physiological contexts including brain function. Using a combination of ancestral reconstruction and circular permutation, we constructed a Förster resonance energy transfer (FRET) biosensor for l‐arginine (cpFLIPR). cpFLIPR displays high sensitivity and specificity, with a Kd of ∼14 µM and a maximal dynamic range of 35%. Importantly, cpFLIPR was highly robust, enabling accurate l‐arginine measurement at physiological temperatures. We established that cpFLIPR is compatible with two‐photon excitation fluorescence microscopy and report l‐arginine concentrations in brain tissue.
Fluorescent sensors are an essential part of the experimental toolbox of the life sciences, where they are used ubiquitously to visualize intra- and extracellular signaling. In the brain, optical ...neurotransmitter sensors can shed light on temporal and spatial aspects of signal transmission by directly observing, for instance, neurotransmitter release and spread. Here we report the development and application of the first optical sensor for the amino acid glycine, which is both an inhibitory neurotransmitter and a co-agonist of the N-methyl-D-aspartate receptors (NMDARs) involved in synaptic plasticity. Computational design of a glycine-specific binding protein allowed us to produce the optical glycine FRET sensor (GlyFS), which can be used with single and two-photon excitation fluorescence microscopy. We took advantage of this newly developed sensor to test predictions about the uneven spatial distribution of glycine in extracellular space and to demonstrate that extracellular glycine levels are controlled by plasticity-inducing stimuli.
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