A method for track reconstruction in the BM@N experiment, based on a constrained combinatorial search for track candidates, i.e. combinations of detector hits possibly belonging to a track, is ...presented. The algorithm has been implemented as a Vector Finder software toolkit containing track reconstruction procedures and tools to define hit acceptance windows (a priori constraints) for the track search. Track reconstruction results for simulated events of heavy-ion interactions are shown demonstrating the performance of the approach proposed.
Context.
Kinematic misalignment between gas and stellar components is observed in a certain fraction of galaxies. It believed to be caused by the acquisition of gas from the external reservoir by, ...for example, major or minor mergers, accretion from cosmological filaments, or the circumgalactic medium.
Aims.
We aim to constrain the possible sources of the gas that forms the counter-rotating component.
Methods.
We derived the gas-phase oxygen abundances of 69 galaxies with a kinematic misalignment between gas and stellar components from the MaNGA DR17 survey and compared them with the metallicity expected according to the mass–metallicity relation.
Results.
We find that the oxygen abundance of the counter-rotating gas in our sample is higher than 8.2 dex, which rules out a significant role for the inflow of pristine gas. Meanwhile, there is a significant difference in the oxygen abundance of the counter-rotating gas between red and blue galaxies. In general, the oxygen abundance is lower than expected for the stellar mass in red galaxies but is compatible with or even higher than typical values for the stellar mass in blue galaxies.
Conclusions.
We show that the exchange of enriched gas between galaxies is the most plausible mechanism for explaining the metallicity of counter-rotating gas components in galaxies of all masses and colors. Meanwhile, minor mergers may play a significant role in the formation of counter-rotating gas components in red and quenched galaxies.
Heavy-ion collisions at NICA energies provide a unique opportunity for the study of the production of hypernuclei in dense baryonic matter. In this paper, the details of the reconstruction procedure ...for hypertritons with the MPD detector in Bi + Bi collisions at NICA energies are presented.
Spontaneous burst firing is a hallmark attributed to the neuronal network activity. It is known to be accompanied by intracellular calcium Са2+i oscillations within the bursting neurons. Studying ...mechanisms underlying regulation of burst firing is highly relevant, since impairment in neuronal bursting accompanies different neurological disorders. In the present study, the contribution of NMDA and GABA(A) receptors to the shape formation of spontaneous burst -was studied in cultured hippocampal neurons. A combination of inhibitory analysis with simultaneous registration of neuronal bursting by whole-cell patch clamp and calcium imaging was used to assess spontaneous burst firing and Са2+i level.
Using bicuculline and D-AP5 we showed that GABA(A) and NMDA receptors effectively modulate burst plateau phase and Са2+i transient spike which can further affect action potential (AP) amplitudes and firing frequency within a burst. Bicuculline significantly elevated the amplitude and reduced the duration of both burst plateau phase and Са2+i spike resulting in an increase of AP firing frequency and shortening of AP amplitudes within a burst. D-AP5 significantly decreases the amplitude of both plateau phase and Са2+i spike along with a burst duration that correlated with an increase in AP amplitudes and reduced firing frequency within a burst. The effect of bicuculline was occluded by co-addition of D-AP5 revealing modulatory role of GABA(A) receptors to the NMDA receptor-mediated formation of the burst.
Our results provide new evidence on importance of NMDA and GABA(A) receptors in shaping burst firing and Ca2+transient spikes in cultured hippocampal neurons.
•GABA(A)R and NMDAR bi-directionally modulate burst plateau phase amplitude.•GABA(A)R and NMDAR bi-directionally modulate burst Ca2+-spike amplitude.•GABA(A)R and NMDAR modulate burst APs amplitude and firing frequency.•NMDAR plays leading role in tuning parameters of the burst.•GABA(A)R modulates NMDAR-mediated tuning of the burst.
Oxygen abundance maps of CALIFA galaxies Zinchenko, I A; Pilyugin, L S; Grebel, E K ...
Monthly notices of the Royal Astronomical Society,
11/2016, Letnik:
462, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We construct maps of the oxygen abundance distribution across the discs of 88 galaxies using Calar Alto Legacy Integral Field Area survey (CALIFA) Data Release 2 (DR2) spectra. The position of the ...centre of a galaxy (coordinates on the plate) was also taken from the CALIFA DR2. The galaxy inclination, the position angle of the major axis, and the optical radius were determined from the analysis of the surface brightnesses in the Sloan Digital Sky Survey (SDSS) g and r bands of the photometric maps of SDSS Data Release 9. We explore the global azimuthal abundance asymmetry in the discs of the CALIFA galaxies and the presence of a break in the radial oxygen abundance distribution. We found that there is no significant global azimuthal asymmetry for our sample of galaxies, i.e. the asymmetry is small, usually lower than 0.05 dex. The scatter in oxygen abundances around the abundance gradient has a comparable value, ...0.05 dex. A significant (possibly dominant) fraction of the asymmetry can be attributed to the uncertainties in the geometrical parameters of these galaxies. There is evidence for a flattening of the radial abundance gradient in the central part of 18 galaxies. We also estimated the geometric parameters (coordinates of the centre, the galaxy inclination and the position angle of the major axis) of our galaxies from the analysis of the abundance map. The photometry-map-based and the abundance-map-based geometrical parameters are relatively close to each other for the majority of the galaxies but the discrepancy is large for a few galaxies with a flat radial abundance gradient. (ProQuest: ... denotes formulae/symbols omitted.)
We determine the radial abundance distributions across the discs of 14 irregular galaxies of the types Sm and Im (morphological T types 9 and 10) as traced by their H ii regions. The oxygen and ...nitrogen abundances in H ii regions are estimated through the T... method or/and with the counterpart method (C method). Moreover, we examine the correspondence between the radial abundance gradient and the surface brightness profile. We find that irregular galaxies with a flat inner profile (flat or outwardly increasing surface brightness in the central region) show shallow (if any) radial abundance gradients. On the other hand, irregular galaxies with a steep inner profile (with or without a bulge or central star cluster) usually show rather steep radial abundance gradients. This is in contrast to the widely held belief that irregular galaxies do not usually show a radial abundance gradient. (ProQuest: ... denotes formulae/symbols omitted.)
The study of the production of hyperons in heavy-ion collisions at NICA energies is among the principal goals in the scientific program of the MPD experiment. In this paper, the details of the ...hyperon reconstruction procedure as well as MPD detector performance for the measurements of the hyperon production in centrality selected Au + Au collisions are presented. The investigation has been performed at the Laboratory of High Energy Physics, JINR.
Abstract
We derive maps of the observed velocity of ionized gas, the oxygen abundance and the extinction (Balmer decrement) across the area of the four spiral galaxies NGC 36, NGC 180, NGC 6063 and ...NGC 7653 from integral field spectroscopy obtained by the Calar Alto Legacy Integral Field Area (CALIFA) survey. We searched for spiral arms through Fourier analysis of the spatial distribution of three tracers (non-circular motion, enhancement of the oxygen abundance and of the extinction) in the discs of our target galaxies. The spiral arms (two-armed logarithmic spirals in the deprojected map) are shown in each target galaxy for each tracer considered. The pitch angles of the spiral arms in a given galaxy obtained with the three different tracers are close to each other. The enhancement of the oxygen abundance in the spiral arms as compared to the abundance in the interarm regions at a given galactocentric distance is small, within a few per cent. We identified a metallicity gradient in our target galaxies. Both barred galaxies in our sample show flatter gradients than the two galaxies without bars. Galactic inclination, position angle of the major axis and the rotation curve were also obtained for each target galaxy using the Fourier analysis of the two-dimensional velocity map.
We constructed an oxygen abundance map and N/O ratio map of the unusually low excitation dwarf irregular galaxy NGC 4163 based on publicly available spectroscopy obtained by the MaNGA survey. We ...detected auroral emission line O IIλλ$$ \lambda \lambda $$7320,7330 which allows us to measure chemical abundance by direct Te$$ {\mathrm{T}}_e $$ method. We found that the scatter of the oxygen abundance derived by the strong line method is large. The oxygen abundances 12 + log(O/H) derived by strong line method vary from ∼7.3$$ \sim 7.3 $$ to ∼7.8$$ \sim 7.8 $$ with a mean value of ∼7.55$$ \sim 7.55 $$. The oxygen abundances derived in two apertures of 2 arcseconds by the direct Te$$ {\mathrm{T}}_e $$ method using our measurements of the O+$$ {\mathrm{O}}^{+} $$ auroral line is about 7.8 dex. The nitrogen‐to‐oxygen ratio log(N/O)$$ \log \left(\mathrm{N}/\mathrm{O}\right) $$ of about −1.5 is typical value for a low metallicity galaxy, maybe slightly shifted towards higher N/O ratios with respect to the N/O values in the H II regions in nearby galaxies. An unusual negative trend between log$$ \log $$(N/O) and oxygen abundance is detected. NGC 4163 is a gas‐poor galaxy with a neutral atomic gas mass fraction of around 0.25. The oxygen abundance in the galaxy is only around 0.1 of the oxygen abundance potentially attainable in a galaxy with such a gas mass fraction. The low metallicity coupled with the low gas mass fraction implies that either the metallicity of the interstellar medium of the galaxy was reduced by pristine gas infall in the recent epoch or the evolution of this galaxy was accompanied by strong galactic winds.
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