Partially-commutative context-free languages

The paper is about a class of languages that extends context-free languages (CFL) and is stable under shuffle. Specifically, we investigate the class of partially-commutative context-free languages (PCCFL), where non-terminal symbols are commutative according to a binary independence relation, very much like in trace theory. The class has been recently proposed as a robust class subsuming CFL and commutative CFL. This paper surveys properties of PCCFL. We identify a natural corresponding automaton model: stateless multi-pushdown automata. We show stability of the class under natural operations, including homomorphic images and shuffle. Finally, we relate expressiveness of PCCFL to two other relevant classes: CFL extended with shuffle and trace-closures of CFL. Among technical contributions of the paper are pumping lemmas, as an elegant completion of known pumping properties of regular languages, CFL and commutative CFL.Comment: In Proceedings EXPRESS/SOS 2012, arXiv:1208.244

Safety verification of asynchronous pushdown systems with shaped stacks

In this paper, we study the program-point reachability problem of concurrent pushdown systems that communicate via unbounded and unordered message buffers. Our goal is to relax the common restriction that messages can only be retrieved by a pushdown process when its stack is empty. We use the notion of partially commutative context-free grammars to describe a new class of asynchronously communicating pushdown systems with a mild shape constraint on the stacks for which the program-point coverability problem remains decidable. Stacks that fit the shape constraint may reach arbitrary heights; further a process may execute any communication action (be it process creation, message send or retrieval) whether or not its stack is empty. This class extends previous computational models studied in the context of asynchronous programs, and enables the safety verification of a large class of message passing programs

Analysis of the correlation between aortic diameter, heart size, and type of coronary circulation

The objective of this study was to analyse the correlation between aortic diameter, heart size, and type of coronary circulation. The study was carried out on 102 human hearts (59 male and 43 female). Casts of the vascular system of each heart were prepared using epoxide resins. The hearts were measured for their size and aorta diameter, and classified to a coronary circulation type. The examination of materials indicated no significant correlation between aortic diameter and sex or coronary circulation type. However, a statistically significant correlation between aortic diameter and heart volume index was found. Folia Morphol 2010; 69, 1: 30-3

Analysis of the influence of heart size and gender on coronary circulation type

Currently, there are many types of classification of coronary circulation. The first type was introduced in 1904 by Banchi. Hettler provides very detailed criteria for the type classification based on the course of the anterior and posterior interventricular branches. Hettler defined the following types: left coronary artery dominance, right coronary artery dominance, and co-dominant. The objective of this study was to analyse coronary circulation types in the studied material and their correlation with heart size and gender. The study was carried out on 102 human hearts (59 male and 43 female). True casts of coronary vessels were obtained using epoxide resins. The prepared specimens were measured for heart dimensions and evaluated for coronary circulation type. The majority of the specimens were classified as the co-dominant type, followed by the right coronary artery dominant type. The left-dominant coronary artery type represented the lowest number of heart specimens. No statistically significant correlation between the type of coronary circulation and heart size or gender was found. The coronary circulation type is not correlated with heart size or with gender. This confirms that it is a hereditary trait. Folia Morphol 2010; 69, 1: 35-4

The ossification of the metacarpal and phalangeal bones in human foetuses

An evaluation was made of the ossification level of the metacarpal and phalangeal bones in human foetuses of both sexes from the 4th to the 9th month of gestation. Our results indicate that ossification of phalangeal bones 1 to 5 always started at the distal end of the phalanx and endochondral ossification prevailed in the proximal phalanx of the thumb

Plant traits explain the success of vacuum harvesting as a method of seed collection for the restoration of species-rich grasslands

Grassland restoration is a key measure for re-establishing damaged floral communities. As seed banks are often degraded, methods are needed to overcome dispersal limitation of the remnant vegetation. One approach is to vacuum harvest seeds from donor sites. While this is a cost-effective method, individual species’ traits describing reproduction methods and dispersal mechanisms may affect the success with which seeds are collected and subsequently germinate. We collected seeds using low-cost vacuum harvesters in species-rich meadows in Poland. We predicted the relative success with which seedlings emerged from this collected material with respect to their percentage cover in the donor sites on the basis of individual species’ functional traits. Prolific species that rely on seed as opposed to vegetative reproduction, and those that germinate in late summer/autumn, exhibited the highest level of emergence. To a lesser extent, drought-tolerant or shade-intolerant species were well represented in the collected material. There was also weak evidence that wind-dispersed seeds would have a higher likelihood of being collected by this method. Our results suggest that vacuum harvesting is a valuable method to collect seeds for use in grassland restoration; however, it has limitations. In particular, additional methods may be needed to introduce into grassland restoration sites the propagules of species that vegetatively reproduce or seed early. The overrepresentation of species that produce large numbers of seed may potentially introduce priority effects that could also have unintended long-term implications for the structure of the floral community

Determination of the total width of the eta' meson

Taking advantage of both the low-emittance proton-beam of the Cooler Synchrotron COSY and the high momentum precision of the COSY-11 detector system, the mass distribution of the eta' meson was measured with a resolution of 0.33 MeV/c^2 (FWHM), improving the experimental mass resolution by almost an order of magnitude with respect to previous results. Based on the sample of more than 2300 reconstructed pp --> pp eta' events the total width of the eta' meson was determined to be 0.226 +- 0.017(stat.) +- 0.014(syst.) MeV/c^2.Comment: 4 pages, 4 figure

System Response Kernel Calculation for List-mode Reconstruction in Strip PET Detector

Reconstruction of the image in Positron Emission Tomographs (PET) requires the knowledge of the system response kernel which describes the contribution of each pixel (voxel) to each tube of response (TOR). This is especially important in list-mode reconstruction systems, where an efficient analytical approximation of such function is required. In this contribution, we present a derivation of the system response kernel for a novel 2D strip PET.Comment: 10 pages, 2 figures; Presented at Symposium on applied nuclear physics and innovative technologies, Cracow, 03-06 June 201

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