The plane-stress ductile fracture of poly(#-caprolactone) (PCL) has been investigated as a function of molecular weight and related crystalline structure. Because of the interacting effects in ...semi-crystalline polymers a separate study of a given structural parameter is rather challenging. Nevertheless, this polymer seems to be a good model material to study the effect of molecular weight on the essential work of fracture, as the interactions between the separate parameters, at room temperature, are negligible. The molecular characteristics of PCL were determined by size exclusion chromatography. To confirm the entangled molecular structure of studied polymers rheological measurements were performed. The crystalline morphology has been characterized by differential scanning calorimetry and wide angle X-ray diffraction. Quasi-static tensile tests and essential work of fracture tests were performed to study the mechanical behavior. Based on the experimental observations an empirical model has been proposed to outline the molecular weight and crystallinity dependence of the essential work of fracture in this semi-crystalline polymer.
Summary of the long term data taking, related to one of the proposed next generation ground-based gravitational detector’s location is presented here. Results of seismic and infrasound noise, ...electromagnetic attenuation and cosmic muon radiation measurements are reported in the underground Matra Gravitational and Geophysical Laboratory near Gyöngyösoroszi, Hungary. The collected seismic data of more than two years is evaluated from the point of view of the Einstein Telescope, a proposed third generation underground gravitational wave observatory. Applying our results for the site selection will significantly improve the signal to noise ratio of the multi-messenger astrophysics era, especially at the low frequency regime.
Dendritic spines can be directly connected to both inhibitory and excitatory presynaptic terminals, resulting in nanometer-scale proximity of opposing synaptic functions. While dually innervated ...spines (DiSs) are observed throughout the central nervous system, their developmental timeline and functional properties remain uncharacterized. Here we used a combination of serial section electron microscopy, live imaging, and local synapse activity manipulations to investigate DiS development and function in rodent hippocampus. Dual innervation occurred early in development, even on spines where the excitatory input was locally silenced. Synaptic NMDA receptor currents were selectively reduced at DiSs through tonic GABAB receptor signaling. Accordingly, spine enlargement normally associated with long-term potentiation on singly innervated spines (SiSs) was blocked at DiSs. Silencing somatostatin interneurons or pharmacologically blocking GABABRs restored NMDA receptor function and structural plasticity to levels comparable to neighboring SiSs. Thus, hippocampal DiSs are stable structures where function and plasticity are potently regulated by nanometer-scale GABAergic signaling.
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•DiSs develop early in spinogenesis, independent of excitatory input•DiSs have reduced structural plasticity compared to SiSs•Reduced DiS plasticity is mediated through GABABR/NMDAR crosstalk•Reduced plasticity may contribute to long term stability of DiSs
Kleinjan et al. demonstrate that formation of hippocampal dually innervated spines (DiSs) occurs early in development and does not require excitatory input. NMDA receptor function and structural plasticity are impaired at DiSs. These effects are mediated through tonic GABAB receptor signaling and may contribute to long-term DiS stability.
We report on the R&D results for a Very High Momentum Particle Identification (VHMPID) detector, which was proposed to extend the charged hadron track-by-track identification in the momentum range ...from 5 to 25 GeV/c in the ALICE experiment at CERN. It is a RICH detector with focusing geometry using pressurized perfluorobutane (C sub(4)F sub(8)O) as a Cherenkov radiator. A MWPC with a CsI photocathode was investigated as the baseline option for the photon detector. The results of beam tests performed on RICH prototypes using both liquid C sub(6)F sub(14) radiator (in proximity focusing geometry for reference measurements) and pressurized C sub(4)F sub(8)O gaseous radiator will be shown in this paper. In addition, we present studies of a CsI based gaseous photon detector equipped with a MWPC having an adjustable anode-cathode gap, aiming at the optimization of the chamber layout and performance in the detection of single photoelectrons.
Detector developments for high performance Muography applications Varga, D.; Nyitrai, G.; Hamar, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Volume:
958
Journal Article
Peer reviewed
Muography allows imaging of large scale objects using cosmic muons. As the observation point needs to be below the object of interest, either the detector is placed underground, and can reveal ...density structures, or, the detector can be on the surface and look sideways, capturing muons closer to the horizon.
As the measurement time is fundamentally limited by the muon flux, long term operation must be achieved with high efficiency. Furthermore, reasonable imaging from a large distance requires good angular resolution. The relevance of addressing the out-of-laboratory environment is demonstrated on the example of a 4 square metre telescope targeting the Sakurajima volcano in Japan.
For open air detectors, the suppression of the low energy (non penetrating) muon background can be reached with a telescope using absorber (scatterer) layers between detector layers with good position resolution. The presented Muography Observation System achieves that using MWPC-s, combined with the relevant servicing systems providing reliable power and gas supply, as well as data acquisition and transfer.
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