Muon colliders offer enormous potential for the exploration of the particle physics frontier but are challenging to realize. A new international collaboration is forming to make such a muon collider ...a reality.
A high-flow radon removal system based on cryogenic distillation was developed and constructed to reduce radon-induced backgrounds in liquid xenon detectors for rare event searches such as XENONnT. A ...continuous purification of the XENONnT liquid xenon inventory of 8.4 tonnes at process flows up to 71 kg/h (200 slpm) is required to achieve a radon reduction by a factor larger than two for radon sources inside the detector. To reach such high flows, the distillation column’s design features liquid xenon inlet and outlets along with novel custom-made bath-type heat exchangers with high liquefaction capabilities. The distillation process was designed using a modification of the McCabe–Thiele approach without a bottom product extraction. The thermodynamic concept is based on a Clausius–Rankine cooling cycle with phase-changing medium, in this case the xenon itself. To drastically reduce the external cooling power requirements, an energy efficient heat pump concept was developed applying a custom-made four cylinder magnetically-coupled piston pump as compressor. The distillation system was operated at thermodynamically stable conditions at a process flow of
(
91
±
2
)
kg
/
h
((
258
±
6
) slpm), 30% over design. With this flow, a
activity concentration
<
1
μ
Bq/kg is expected inside the XENONnT detector given the measured radon source distribution.
We report on a search for weakly interacting massive particles (WIMPs) using 278.8 days of data collected with the XENON1T experiment at LNGS. XENON1T utilizes a liquid xenon time projection chamber ...with a fiducial mass of (1.30±0.01) ton, resulting in a 1.0 ton yr exposure. The energy region of interest, 1.4,10.6 keV_{ee} (4.9,40.9 keV_{nr}), exhibits an ultralow electron recoil background rate of 82_{-3}^{+5}(syst)±3(stat) events/(ton yr keV_{ee}). No significant excess over background is found, and a profile likelihood analysis parametrized in spatial and energy dimensions excludes new parameter space for the WIMP-nucleon spin-independent elastic scatter cross section for WIMP masses above 6 GeV/c^{2}, with a minimum of 4.1×10^{-47} cm^{2} at 30 GeV/c^{2} and a 90% confidence level.
The impact of synchrotron radiation at the Compact Linear Collider Arominski, D.; Sailer, A.; Latina, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2020, Letnik:
983, Številka:
C
Journal Article
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Synchrotron radiation (SR) emission and interactions with the vacuum chamber walls have the potential to negatively impact the performance of future electron–positron colliders. The Beam Delivery ...System (BDS) of the Compact Linear Collider (CLIC) contains weak bending and multipole magnets that lead to less intense emissions than at circular colliders with similar centre-of-mass energies. However, the linear geometry more easily allows for multiple reflections of SR photons, that can travel further downstream in the accelerator and impact the detector region. In this study, the results of PLACET and Synrad+ simulations of photon emissions and reflections in the CLIC BDS at two energy stages of 380GeV and 3TeV are presented. Estimates are given for heating and outgassing caused by SR photons interacting with the vacuum chamber in the BDS. The occupancy levels in the tracking detectors coming from full-detector simulations in Geant4 are presented. Optimised beam pipe apertures are proposed for the forward detector region, as well as mitigation methods to ensure the safety and best possible performance of the detector.
In patients with obesity and type 2 diabetes, adipose tissue is infiltrated by macrophages known to alter adipogenesis of mesenchymal precursor cells via secretion of proinflammatory cytokines. ...Recently, it has been shown that under certain conditions, immune cells can also express wnt-5a, a factor known to inhibit adipogenesis in humans. Therefore, in this study we aimed to investigate whether macrophages affect adipogenesis of mesenchymal precursor cells via wnt-5a. Wnt-5a was found to be expressed in adipose tissue macrophages in obese and type 2 diabetic human subjects in vivo by immunohistochemistry of adipose tissue biopsies. Furthermore, wnt-5a was detectable in circulating CD14+ blood monocytes of human subjects with obesity and type 2 diabetes on RNA level by real-time PCR. Besides expression analysis in vivo, we also performed functional studies to explore the role of wnt-5a in low-grade inflammation of adipose tissue. In a cell culture experiment, macrophage-conditioned differentiation medium inhibited adipogenesis of 3T3-L1 cells. This inhibitory effect was restored by adding neutralising anti-wnt-5a antibodies. In conclusion, our data indicate that macrophages alter adipogenesis of 3T3-L1 cells not only via classical proinflammatory cytokines, but also via wnt signalling molecules.
The coevolution between hosts and parasites is predicted to have complex evolutionary consequences for both antagonists, often within short time periods. To date, conclusive experimental support for ...the predictions is available mainly for microbial host systems, but for only a few multicellular host taxa. We here introduce a model system of experimental coevolution that consists of the multicellular nematode host Caenorhabditis elegans and the microbial parasite Bacillus thuringiensis. We demonstrate that 48 host generations of experimental coevolution under controlled laboratory conditions led to multiple changes in both parasite and host. These changes included increases in the traits of direct relevance to the interaction such as parasite virulence (i.e., host killing rate) and host resistance (i.e., the ability to survive pathogens). Importantly, our results provide evidence of reciprocal effects for several other central predictions of the coevolutionary dynamics, including (i) possible adaptation costs (i.e., reductions in traits related to the reproductive rate, measured in the absence of the antagonist), (ii) rapid genetic changes, and (iii) an overall increase in genetic diversity across time. Possible underlying mechanisms for the genetic effects were found to include increased rates of genetic exchange in the parasite and elevated mutation rates in the host. Taken together, our data provide comprehensive experimental evidence of the consequences of host-parasite coevolution, and thus emphasize the pace and complexity of reciprocal adaptations associated with these antagonistic interactions.
Intermediate progenitor cells constitute a second proliferative cell type in the developing mammalian cerebral cortex. Little is known about the factors that govern the production of intermediate ...progenitors. Although persistent expression of stabilized beta-catenin was found to delay the maturation of radial glial progenitors into intermediate progenitors, the relationship between beta-catenin signaling and intermediate progenitors remains poorly understood. Using a transgenic reporter mouse for Axin2, a direct target of Wnt/beta-catenin signaling, we observed that beta-catenin signaling is decreased in intermediate progenitor cells relative to radial glial progenitors. Conditional deletion of beta-catenin from mouse cortical neural progenitors increased intermediate progenitor numbers, while conditional expression of stabilized beta-catenin reduced the intermediate progenitor population. Together, these findings provide evidence that beta-catenin signaling in radial progenitors negatively regulates intermediate progenitor cell number during cortical development.
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