An electrostatic brightness-enhanced timed positron beam for atomic collision experiments

An electrostatic positron beam, incorporating a remoderation stage to yield brightness enhancement with time-of-flight capabilities, has been developed and characterized. The beam is tunable in an energy range (5–500) eV with an angular divergence of ≃ 1° and an energy resolution of ≲ 1%

Strong projectile-energy dependence of the Auger-line intensity at 0° due to Coulomb focusing in fast proton-neon collisions

L

Comparison of the perioperative time courses of matrix metalloproteinase-9 (MMP-9) and its inhibitor (TIMP-1) during carotid artery stenting (CAS) and carotid endarterectomy (CEA)

Abstract Background Our aim was to compare the perioperative time courses of matrix metalloproteinase-9 (MMP-9) and its inhibitor (TIMP-1) in during carotid endarterectomy (CEA) and carotid artery stenting (CAS). Methods In our prospective study, twenty-five patients who were scheduled to undergo CAS were enrolled. We used a matched, historical CEA group as controls. Blood samples were collected at four time points: T1: preoperative; T2: 60 min after stent insertion; T3: first postoperative morning; and T4: third postoperative morning. Plasma MMP-9 and TIMP-1 levels were measured by ELISA. Results In the CEA group, the plasma levels of MMP-9 were significantly elevated at T3 compared to T1. In the CAS group, there was no significant difference in MMP-9 levels in the perioperative period. MMP-9 levels were significantly higher in the T3 samples of the CEA group compared to the CAS group. Significantly lower TIMP-1 levels were measured in both groups at T2 than at T1 in both groups. MMP-9/TIMP-1 at T3 was significantly higher than that at T1 in the CEA group compared to both T1 and the CAS group. Conclusions CAS triggers smaller changes in the MMP-9-TIMP-1 system during the perioperative period, which may correlate with a lower incidence of central nervous system complications. Additional studies as well as cognitive and functional surveys are warranted to determine the clinical relevance of our findings. Trial registration NIH U.S. National Library of Medicine, Clinicaltrials.gov,NCT03410576, 24.01.2018, Retrospectively registere

A method for intensity calibration of an electron spectrometer with multi-angle detection

A special electrostatic electron spectrometer designed for precise and unique experiments and an inten- sity calibration method for universal application in electron spectroscopy are presented. The upgrade of the analyzer enables the intensity calibration at arbitrary electron energies using elastically scattered electrons. In order to test the calibration procedure the double differential (in energy and angle) ioniza- tion cross sections (DDCS) of electrons ejected from 300 keV proton-argon collisions were measured and compared with the data of Rudd et al. [1]. The good agreement between the two data sets verifies the applicability of the calibration method

Moderation and diffusion of positrons in tungsten meshes and foils.

The efficiency of tungsten meshes and thin foils for moderation of fast positrons from 22Na has been investigated in transmission geometry and a fair agreement has been found with previous experimental results where directly comparable. For foils, the dependence on material thickness is found to be similar to the prediction of the Vehanen-M€akinen diffusion model; however, the magnitude is 5–10 times lower. A broad consensus is observed between experiment and the results of a three-dimensional model developed in this work. For a given thickness, meshes are found to be generally better than foils by around a factor of 10 with a maximum efficiency (�10�3) comparable to that achieved with thin single crystal foils, in accord with previous measurements and the results of the present model