Discrete symmetries tested at 10 precision using linear polarization of photons from positronium annihilations.

Discrete symmetries play an important role in particle physics with violation of CP connected to the matter-antimatter imbalance in the Universe. We report the most precise test of P, T and CP invariance in decays of ortho-positronium, performed with methodology involving polarization of photons from these decays. Positronium, the simplest bound state of an electron and positron, is of recent interest with discrepancies reported between measured hyperfine energy structure and theory at the level of 10 signaling a need for better understanding of the positronium system at this level.

The Rectifying Contact of Hydrated Different Size YSZ Nanoparticles for Advanced Electronics.

The paper considers the new effects of the nanoscale state of matter, which open up prospects for the development of electronic devices using new physical principles. The contacts of chemically homogeneous nanoparticles of yttrium-stabilized zirconium oxide (ZrO2—x mol% Y2O3, x = 0, 3, 4, 8; YSZ) with different sizes of 7.5 nm and 9 nm; 7.

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography.

Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron-positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by knowledge of the latter.

3D TOF-PET image reconstruction using total variation regularization.

In this paper we introduce a semi-analytic algorithm for 3-dimensional image reconstruction for positron emission tomography (PET). The method consists of the back-projection of the acquired data into the most likely image voxel according to time-of-flight (TOF) information, followed by the filtering step in the image space using an iterative optimization algorithm with a total variation (TV) regularization. TV regularization in image space is more computationally efficient than usual iterative optimization methods for PET reconstruction with full system matrix that use TV regularization.

Studies on healthy and neoplastic tissues using positron annihilation lifetime spectroscopy and focused histopathological imaging.

Samples of healthy and neoplastic myometrial tissues were investigated using Positron Annihilation Lifetime Spectroscopy (PALS). Meaningful differences between normal and diseased tissues were observed for each patient. The differences were also clearly visible for various kinds of lesions in each patient.

Performance assessment of the 2 γpositronium imaging with the total-body PET scanners.

Purpose: In living organisms, the positron-electron annihilation (occurring during the PET imaging) proceeds in about 30% via creation of a metastable ortho-positronium atom. In the tissue, due to the pick-off and conversion processes, over 98% of ortho-positronia annihilate into two 511 keV photons. In this article, we assess the feasibility for reconstruction of the mean ortho-positronium lifetime image based on annihilations into two photons.

Estimating relationship between the time over threshold and energy loss by photons in plastic scintillators used in the J-PET scanner.

Purpose: The time-over-threshold (TOT) technique is being used widely due to itsimplications in developing the multi-channel readouts, mainly when fast signal processing is required. Using the TOT technique, as a measure of energy loss instead of charge integration methods, significantly reduces the signal readout costs by combining the time and energy information. Therefore, this approach can potentially be utilized in J-PET tomograph which is built from plastic scintillators characterized by fast light signals.

Free volume in the smectic-E phase of 4-hexyl-4' isothiocyanatobiphenyl studied by positron annihilation spectroscopy.

Positron annihilation lifetime spectroscopy has been used to study 4-hexyl-4'-isothiocyanatobiphenyl. Changes of the orthopositronium lifetime parameters with temperature have been observed for the supercooled smectic-E phase. The measurements confirm that positronium is created and annihilates in a layer of a lower electron density containing alkyl chains of molecules.

Feasibility study of the positronium imaging with the J-PET tomograph.

A detection system of the conventional PET tomograph is set-up to record data from [Formula: see text] annihilation into two photons with energy of 511 keV, and it gives information on the density distribution of a radiopharmaceutical in the body of the object. In this paper we explore the possibility of performing the three gamma photons imaging based on ortho-positronium annihilation, as well as the possibility of positronium mean lifetime imaging with the J-PET tomograph constructed from plastic scintillators. For this purposes simulations of the ortho-positronium formation and its annihilation into three photons were performed taking into account distributions of photons' momenta as predicted by the theory of quantum electrodynamics and the response of the J-PET tomograph.

Feasibility studies of the polarization of photons beyond the optical wavelength regime with the J-PET detector.

J-PET is a detector optimized for registration of photons from the electron-positron annihilation via plastic scintillators where photons interact predominantly via Compton scattering. Registration of both primary and scattered photons enables to determinate the linear polarization of the primary photon on the event by event basis with a certain probability. Here we present quantitative results on the feasibility of such polarization measurements of photons from the decay of positronium with the J-PET and explore the physical limitations for the resolution of the polarization determination of 511 keV photons via Compton scattering.

Evaluation of Single-Chip, Real-Time Tomographic Data Processing on FPGA SoC Devices.

A novel approach to tomographic data processing has been developed and evaluated using the Jagiellonian positron emission tomography scanner as an example. We propose a system in which there is no need for powerful, local to the scanner processing facility, capable to reconstruct images on the fly. Instead, we introduce a field programmable gate array system-on-chip platform connected directly to data streams coming from the scanner, which can perform event building, filtering, coincidence search, and region-of-response reconstruction by the programmable logic and visualization by the integrated processors.

Estimating the NEMA characteristics of the J-PET tomograph using the GATE package.

A novel whole-body positron emission tomography (PET) system based on plastic scintillators is developed by the J-PET Collaboration. It consists of plastic scintillator strips arranged axially in the form of a cylinder, allowing the cost-effective construction of the total-body PET system. In order to determine the properties of the scanner prototype and optimize its geometry, advanced computer simulations were performed using the GATE (Geant4 application for tomographic emission) software.

Novel scintillating material 2-(4-styrylphenyl)benzoxazole for the fully digital and MRI compatible J-PET tomograph based on plastic scintillators.

A novel plastic scintillator is developed for the application in the digital positron emission tomography (PET). The novelty of the concept lies in application of the 2-(4-styrylphenyl)benzoxazole as a wavelength shifter. The substance has not been used as scintillator dopant before.

Calculation of the time resolution of the J-PET tomograph using kernel density estimation.

In this paper we estimate the time resolution of the J-PET scanner built from plastic scintillators. We incorporate the method of signal processing using the Tikhonov regularization framework and the kernel density estimation method. We obtain simple, closed-form analytical formulae for time resolution.

A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators.

We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.

Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph.

Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns.

Positron annihilation studies of 4-n-butyl-4'-isothiocyanato-1,1'-biphenyl.

Positron annihilation lifetime spectroscopy (PALS) measurements were performed between 93 and 293 K in order to study the supercooled smectic-E (Sm-E) phase of 4-n-butyl-4'-isothiocyanato-1,1'-biphenyl (4TCB), the ordered molecular crystal of 4TCB, and the phase transition between the Sm-E phase and the ordered molecular crystal of 4TCB. The phase transition was well reflected in the abrupt increase of the ortho-positronium (o-Ps) lifetime and intensity. The value of the o-Ps lifetime in the Sm-E liquid crystalline phase of 4TCB, i.

[Acute neurologic rubella complications observed in children of southeastern Poland during rubella epidemics in 1986 and 1992].

During the last two rubella epidemics in 1985-1986 and 1992, 24 children (15 boys and 9 girls) were hospitalized with acute neurological complications manifested in the first week of clinical symptoms of rubella. Average age of patients was 9 years (3-15 years). Acute rubella encephalitis (ARE) was diagnosed in 22 cases.

The comparison of pepsin and trypsin action on goat, cow, mare and human caseins.

The degree of proteolysis of micellar caseins of human, goat's, mare's and two breeds (Black&White and Red Polish) of cow's milk was compared for pepsin and trypsin action in vitro. Human and goat's caseins were hydrolysed in 100% and 96%, respectively, mare's casein--92%, Black&White cow's casein--90%, Red Polish cow's casein--76%. The differences can be related to the micelle structure, especially to the prevalence of beta casein in the human and goat's casein.

[In vitro evaluation of susceptibility to selected antibiotics of strains of staphylococcus aureus isolated from purulent skin changes].

Resistance to antibiotics of Staphylococcus aureus strains isolated from purulent skin changes during the years 1987-1991 was investigated. The antibiogram was performed by the disc-diffusion method. Susceptibility to penicillin, ampicillin, cloxacillin, gentamicin, doxycycline, erythromycin, tetracycline, and lincomycin was determined.

[Studies on the effect of cephradine, cefuroxime, lincomycin and amikacin on complement levels in experimental animals].

Rabbits were injected intramuscularily with antibiotics in mean therapeutic doses (calculated by body weight) for the period of 7 days. Group I received cephradine, group II--cefuroxime, group III--lincomycin and group IV--amikacin. Determination of complement level by CH50 method was performed before application of antibiotics and at 7, 14, 28 and 42 day of the study.

[Studies of the effect of cephradine and lincomycin on dynamics of selected parameters of nonspecific cellular immunity in experimental animals].

Rabbits of group I received cephradine i.m. and of group II lincomycin in mean therapeutic doses (calculated by body weight) for seven days.

[Investigations concerning the influence of cefuroxime and amikacin on dynamics of selected parameters of nonspecific cellular immunity in experimental animals].

Rabbits divided into two groups were injected intramuscularly antibiotics amikacin or cefuroxime in doses corresponding to mean therapeutic doses for seven days. Blood samples for determination of values of phagocytosis reaction (percentage of phagocytizing neutrophils, phagocyte index) and NBT test were taken before application of antibiotics and on 7, 14, 28 and 42 day of study. After application of cefuroxime significant decrease of NBT value was observed at the 14th day, whereas the percentage of phagocytizing neutrophils was changing at 7 and 14 day.

[Susceptibility to nitrofurantoin, biseptol and nalidixic acid of E. coli strains isolated from urine in the years 1983-1990].

The group of microorganisms causing urinary tract infections includes the Enterobacteriaceae family, particularly E. coli, being the most commonly detected etiologic factor of the above infections. Research was conducted from 1983 to 1990 on 1102 E.

[Studies of susceptibility to antibiotics in strains of E. coli isolated from urine in the years 1986-1990].

From 1986 to 1990 research was conducted on E. coli strains isolated from patients with clinical symptoms of urinary tract infection. The paper-disk-plate technique was applied to determine their susceptibility to ampicillin, carbenicillin, azlocillin, cefamandole, cefotaxime, ceftriaxone, ceftazidime, cefoperazone, amikacin, netilmicin, gentamycin, vibramycin, and colistin.