Correct human cardiac nomenclature

Proper heart’s nomenclature is very important in daily clinical practice and research studies, andwhen it is consistent, it can facilitate better communication between different medical specialists. Thegeneral rule of the anatomy is to describe organs and their structures in attitudinally correct position.However, the use of the old-fashioned Valentine position (where the heart is described as if it werestanding on its apex) is still in use to describe important cardiac structures. Upon closer analysis, all main chambers of the heart and their associated subcomponents have mislabeled structures that should be renamed. In this article we aimed to emphasize the limitations of Valentinian nomenclature, presentproper anatomical names of the most important heart’s structures and advocate to change certain mis-labeled anatomical structures. Attitudinally correct designations presented in this study will benefit allmedical specialties, and they will reinforce the importance of consistent orientational naming. Correctnaming of heart’s structures will also help improve communication between different medical specialists

Studies of unicellular micro-organisms Saccharomyces cerevisiae by means of Positron Annihilation Lifetime Spectroscopy

Results of Positron Annihilation Lifetime Spectroscopy (PALS) and microscopic studies on simple microorganisms: brewing yeasts are presented. Lifetime of ortho - positronium (o-Ps) were found to change from 2.4 to 2.9 ns (longer lived component) for lyophilised and aqueous yeasts, respectively. Also hygroscopicity of yeasts in time was examined, allowing to check how water - the main component of the cell - affects PALS parameters, thus lifetime of o-Ps were found to change from 1.2 to 1.4 ns (shorter lived component) for the dried yeasts. The time sufficient to hydrate the cells was found below 10 hours. In the presence of liquid water an indication of reorganization of yeast in the molecular scale was observed. Microscopic images of the lyophilised, dried and wet yeasts with best possible resolution were obtained using Inverted Microscopy (IM) and Environmental Scanning Electron Microscopy (ESEM) methods. As a result visible changes to the surface of the cell membrane were observed in ESEM images.Comment: Nukleonika (2015

Searches for discrete symmetries violation in ortho-positronium decay using the J-PET detector

In this paper we present prospects for using the J-PET detector to search for discrete symmetries violations in a purely leptonic system of the positronium atom. We discuss tests of CP and CPT symmetries by means of ortho-positronium decays into three photons. No zero expectation values for chosen correlations between ortho-positronium spin and momentum vectors of photons would imply the existence of physics phenomena beyond the Standard Model. Previous measurements resulted in violation amplitude parameters for CP and CPT symmetries consistent with zero, with an uncertainty of about 10-3. The J-PET detector allows to determine those values with better precision thanks to a unique time and angular esolution combined with a high geometrical acceptance. Achieving the aforementioned is possible due to application of polymer scintillators instead of crystals as detectors of annihilation quanta.Comment: in Nukleonika 201

Beam profile investigation of the new collimator system for the J-PET detector

Jagiellonian Positron Emission Tomograph (J-PET) is a multi-purpose detector which will be used for search for discrete symmetries violations in the decays of positronium atoms and for investigations with positronium atoms in life-sciences and medical diagnostics. In this article we present three methods for determination of the beam profile of collimated annihilation gamma quanta. Precise monitoring of this profile is essential for time and energy calibration of the J-PET detector and for the determination of the library of model signals used in the hit-time and hit-position reconstruction. We have we have shown that usage of two lead bricks with dimensions of 5x10x20 cm^3 enables to form a beam of annihilation quanta with Gaussian profile characterized by 1 mm FWHM. Determination of this characteristic is essential for designing and construction the collimator system for the 24-module J-PET prototype. Simulations of the beam profile for different collimator dimensions were performed. This allowed us to choose optimal collimation system in terms of the beam profile parameters, dimensions and weight of the collimator taking into account the design of the 24 module J-PET detector.Comment: 14 pages, 9 figure

PALS investigations of free volumes thermal expansion of J-PET plastic scintillator synthesized in polystyrene matrix

The polystyrene dopped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter, prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260 K, 283 K and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the significant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.Comment: in Nukleonika 201

Processing optimization with parallel computing for the J-PET tomography scanner

The Jagiellonian-PET (J-PET) collaboration is developing a prototype TOF-PET detector based on long polymer scintillators. This novel approach exploits the excellent time properties of the plastic scintillators, which permit very precise time measurements. The very fast, FPGA-based front-end electronics and the data acquisition system, as well as, low- and high-level reconstruction algorithms were specially developed to be used with the J-PET scanner. The TOF-PET data processing and reconstruction are time and resource demanding operations, especially in case of a large acceptance detector, which works in triggerless data acquisition mode. In this article, we discuss the parallel computing methods applied to optimize the data processing for the J-PET detector. We begin with general concepts of parallel computing and then we discuss several applications of those techniques in the J-PET data processing.Comment: 8 page

Trilateration-based reconstruction of ortho-positronium decays into three photons with the J-PET detector

This work reports on a new reconstruction algorithm allowing to reconstruct the decays of ortho-positronium atoms into three photons using the places and times of photons recorded in the detector. The method is based on trilateration and allows for a simultaneous reconstruction of both location and time of the decay. Results of resolution tests of the new reconstruction in the J-PET detector based on Monte Carlo simulations are presented, which yield a spatial resolution at the level of 2 cm (FWHM) for X and Y and at the level of 1 cm (FWHM) for Z available with the present resolution of J-PET after application of a kinematic fit. Prospects of employment of this method for studying angular correlations of photons in decays of polarized ortho-positronia for the needs of tests of CP and CPT discrete symmetries are also discussed. The new reconstruction method allows for discrimination of background from random three-photon coincidences as well as for application of a novel method for determination of the linear polarization of ortho-positronium atoms, which is also introduced in this work.Comment: 18 pages, 5 figures. Accepted for publication in Nuclear Instrumentation and Methods in Physics Research

Potential of the J-PET detector for studies of discrete symmetries in decays of positronium atom - a purely leptonic system

The Jagiellonian Positron Emission Tomograph (J-PET) was constructed as a prototype of the cost-effective scanner for the simultaneous metabolic imaging of the whole human body. Being optimized for the detection of photons from the electron-positron annihilation with high time- and high angular-resolution, it constitutes a multi-purpose detector providing new opportunities for studying the decays of positronium atoms. Positronium is the lightest purely leptonic object decaying into photons. As an atom bound by a central potential it is a parity eigenstate, and as an atom built out of an electron and an anti-electron it is an eigenstate of the charge conjugation operator. Therefore, the positronium is a unique laboratory to study discrete symmetries whose precision is limited in principle by the effects due to the weak interactions expected at the level of (~10$^{-14}$) and photon-photon interactions expected at the level of (~10$^{-9}$). The J-PET detector enables to perform tests of discrete symmetries in the leptonic sector via the determination of the expectation values of the discrete-symmetries-odd operators, which may be constructed from the spin of ortho-positronium atom and the momenta and polarization vectors of photons originating from its annihilation. In this article we present the potential of the J-PET detector to test the C, CP, T and CPT symmetries in the decays of positronium atoms.Comment: 27 pages, 6 figure

Multichannel FPGA based MVT system for high precision time (20~ps~RMS) and charge measurement

In this article it is presented an FPGA based $M$ulti-$V$oltage $T$hreshold (MVT) system which allows of sampling fast signals ($1-2$ ns rising and falling edge) in both voltage and time domain. It is possible to achieve a precision of time measurement of $20$ ps RMS and reconstruct charge of signals, using a simple approach, with deviation from real value smaller than 10$\%$. Utilization of the differential inputs of an FPGA chip as comparators together with an implementation of a TDC inside an FPGA allowed us to achieve a compact multi-channel system characterized by low power consumption and low production costs. This paper describes realization and functioning of the system comprising 192-channel TDC board and a four mezzanine cards which split incoming signals and discriminate them. The boards have been used to validate a newly developed Time-of-Flight Positron Emission Tomography system based on plastic scintillators. The achieved full system time resolution of $\sigma$(TOF) $\approx 68$ ps is by factor of two better with respect to the current TOF-PET systems.Comment: Accepted for publication in JINST, 10 pages, 8 figure