STING (stimulator of interferon genes) is a cytosolic sensor for cyclic dinucleotides and also an adaptor molecule for intracellular DNA receptors. Although STING has important functions in the host ...defense against pathogens and in autoimmune diseases, its physiological relevance in intestinal homeostasis is largely unknown. In this study, we show that STING
mice presented defective protective mechanisms of intestinal mucosa, including decreased number of goblet cells, diminished mucus production, and lower levels of secretory IgA, when compared with wild-type (WT) mice. Fecal content and microbiota DNA could activate STING, indicating a role of this molecule in gut. Microbiota composition was altered in STING
mice toward a more inflammatory profile, evidencing a reduction in the Allobacolum and Bifidobacterium groups along with increase in Disulfovibrio bacteria. Absence of STING lead to decrease in induced intraepithelial lymphocytes (IEL) and to increase in group 1 innate lymphoid cell (ILC1) as well as ILC3 frequencies and decrease in ILC2 in the colon. Development and function of Foxp3+ and LAP+ regulatory T cells were also compromised in STING
mice. Moreover, these mice were highly susceptible to dextran sodium sulfate-induced colitis, T-cell-induced colitis, and enteric Salmonella typhimurium infection when compared with WT animals. Therefore, our results identify an important role of STING in maintaining gut homeostasis and also a protective effect in controlling gut inflammation.
Accurate knowledge of the charge and Zemach radii of the proton is essential, not only for understanding its structure but also as input for tests of bound-state quantum electrodynamics and its ...predictions for the energy levels of hydrogen. These radii may be extracted from the laser spectroscopy of muonic hydrogen (μp, that is, a proton orbited by a muon). We measured the $2{\mathrm{S}}_{1/2}^{\mathrm{F}=0}-2{\mathrm{P}}_{3/2}^{\mathrm{F}=1}$ transition frequency in μp to be 54611.16(1.05) gigahertz (numbers in parentheses indicate one standard deviation of uncertainty) and reevaluated the $2{\mathrm{S}}_{1/2}^{\mathrm{F}=1}-2{\mathrm{P}}_{3/2}^{\mathrm{F}=1}$ transition frequency, yielding 49881.35(65) gigahertz. From the measurements, we determined the Zemach radius, r Z = 1.082(37) femtometers, and the magnetic radius, r M = 0.87(6) femtometer, of the proton. We also extracted the charge radius, r E = 0.84087(39) femtometer, with an order of magnitude more precision than the 2010-CODATA value and at 7σ variance with respect to it, thus reinforcing the proton radius puzzle.
The hadronic width of the ground state of pionic hydrogen has been redetermined by X-ray spectroscopy to be
Γ
1
s
π
H
=
(
856
±
16
stat
±
22
sys
)
meV. The experiment was performed at the ...high-intensity low-energy pion beam of the Paul Scherrer Institute by using the cyclotron trap and a high-resolution Bragg spectrometer with spherically bent crystals. Coulomb de-excitation was studied in detail by comparing its influence on the line shape by measuring the three different transitions K
α
, K
β
, and K
γ
at various hydrogen densities. The pion-nucleon scattering lengths and other physical quantities extracted from pionic-atom data are in good agreement with the results obtained from pion-nucleon and nucleon-nucleon scattering experiments and confirm that a consistent picture is achieved for the low-energy pion-nucleon sector with respect to the expectations of chiral perturbation theory.
A good understanding of electroluminescence is a prerequisite when optimising double-phase noble gas detectors for Dark Matter searches and high-pressure xenon TPCs for neutrinoless double beta decay ...detection.
A simulation toolkit for calculating the emission of light through electron impact on neon, argon, krypton and xenon has been developed using the Magboltz and Garfield programs. Calculated excitation and electroluminescence efficiencies, electroluminescence yield and associated statistical fluctuations are presented as a function of electric field. Good agreement with experiment and with Monte Carlo simulations has been obtained.
A
bstract
The NEXT experiment aims to observe the neutrinoless double beta decay of
136
Xe in a high-pressure xenon gas TPC using electroluminescence (EL) to amplify the signal from ionization. One ...of the main advantages of this technology is the possibility to reconstruct the topology of events with energies close to
Q
ββ
. This paper presents the first demonstration that the topology provides extra handles to reject background events using data obtained with the NEXT-DEMO prototype.
Single electrons resulting from the interactions of
22
Na 1275 keV gammas and electronpositron pairs produced by conversions of gammas from the
228
Th decay chain were used to represent the background and the signal in a double beta decay. These data were used to develop algorithms for the reconstruction of tracks and the identification of the energy deposited at the end-points, providing an extra background rejection factor of 24
.
3 ± 1
.
4 (stat.)%, while maintaining an efficiency of 66
.
7 ± 1
.
% for signal events.
The energy levels of hydrogen-like atomic systems can be calculated with great precision. Starting from their quantum mechanical solution, they have been refined over the years to include the ...electron spin, the relativistic and quantum field effects, and tiny energy shifts related to the complex structure of the nucleus. These energy shifts caused by the nuclear structure are vastly magnified in hydrogen-like systems formed by a negative muon and a nucleus, so spectroscopy of these muonic ions can be used to investigate the nuclear structure with high precision. Here we present the measurement of two 2S-2P transitions in the muonic helium-4 ion that yields a precise determination of the root-mean-square charge radius of the α particle of 1.67824(83) femtometres. This determination from atomic spectroscopy is in excellent agreement with the value from electron scattering
, but a factor of 4.8 more precise, providing a benchmark for few-nucleon theories, lattice quantum chromodynamics and electron scattering. This agreement also constrains several beyond-standard-model theories proposed to explain the proton-radius puzzle
, in line with recent determinations of the proton charge radius
, and establishes spectroscopy of light muonic atoms and ions as a precise tool for studies of nuclear properties.
Precision spectroscopy of light muonic atoms provides unique information about the atomic and nuclear structure of these systems and thus represents a way to access fundamental interactions, ...properties and constants. One application comprises the determination of absolute nuclear charge radii with unprecedented accuracy from measurements of the 2S - 2P Lamb shift. Here, we review recent results of nuclear charge radii extracted from muonic hydrogen and helium spectroscopy and present experiment proposals to access light muonic atoms with Z ≥ 3. In addition, our approaches towards a precise measurement of the Zemach radii in muonic hydrogen (μp) and helium (μ3He+) are discussed. These results will provide new tests of bound-state quantum-electrodynamics in hydrogen-like systems and can be used as benchmarks for nuclear structure theories.
•New experimental data for AA6201-T81 wires under fretting fatigue.•Nonlocal life estimation approach for wires of overhead conductors.•Effective procedure to obtain the size of the fatigue process ...zone.•Elastic-plastic contact model significantly improved estimated lives.
Fretting fatigue tests were conducted on 6201-T81 aluminum alloy wires of an AAAC 900 MCM conductor. A finite element-based contact model combined with a nonlocal Smith–Watson–Topper criterion was used to estimate fatigue life. To account for the stress gradients beneath the contact, an average stress over a fatigue damage zone was adopted. A procedure for determining the size of the damage zone from V-notched wire test data is presented. Fatigue lives estimated using stresses from a linear elastic contact model were overly conservative, while the use of an elastic-plastic contact model significantly improved the estimates.
The experimental outcomes of small-animal positron emission tomography (PET) imaging with
18
F-labelled fluorodeoxyglucose (
18
F-FDG) can be particularly compromised by animal preparation and care. ...Several works intend to improve research reporting and amplify the quality and reliability of published research. Though these works provide valuable information to plan and conduct animal studies, manuscripts describe different methodologies—standardization does not exist. Consequently, the variation in details reported can explain the difference in the experimental results found in the literature. Additionally, the resources and guidelines defining protocols for small-animal imaging are scarce, making it difficult for researchers to obtain and compare accurate and reproducible data. Considering the selection of suitable procedures key to ensure animal welfare and research improvement, this paper aims to prepare the way for a future guideline on mice preparation and care for PET imaging with
18
F-FDG. For this purpose, a global standard protocol was created based on recommendations and good practices described in relevant literature.
Lately, the use of zebrafish has gained increased interest in the scientific community as an animal model in preclinical research. However, there is a lack of
in vivo
imaging tools that ensure animal ...welfare during acquisition procedures. The use of functional imaging techniques, like Positron Emission Tomography (PET), in zebrafish is limited since it requires the animal to be alive, representing a higher instrumentation complexity when compared to morphological imaging systems. In the present work, a new zebrafish enclosure was developed to acquire
in vivo
images while monitoring the animal’s welfare through its heartbeat. The temperature, dissolved oxygen, and pH range in a closed aquatic environment were tested to ensure that the conditions stay suitable for animal welfare during image acquisitions. The developed system, based on an enclosure with a bed and heartbeat sensors, was tested under controlled conditions in anesthetized fishes. Since the anesthetized zebrafish do not affect the water quality over time, there is no need to incorporate water circulation for the expected time of PET exams (about 30 min). The range of values obtained for the zebrafish heart rate was 88–127 bpm. The developed system has shown promising results regarding the zebrafish’s heart rate while keeping the fish still during the long imaging exams. The zebrafish enclosure ensures the animal’s well-being during the acquisition of
in vivo
images in different modalities (PET, Computer Tomography, Magnetic Resonance Imaging), contributing substantially to the preclinical research.
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