343 research outputs found
Kinematic differences between NLS1 and BLAGN sources
It is well-known that the higher policyclic aromatic hydrocarbon (PAH)
abundance, lower black hole mass, higher accretion rate and lower luminosities
are among the major characteristics of Narrow-Line Seyfert galaxies (NLS1),
when they are compared to Broad line Seyfert galaxies (BLS1). NLS1s may be
normal Seyfert galaxies at an early stage of evolution, their black holes may
still be growing and/or they could be special for some other reason. In this
work we discuss the findings that NLS1s have most of line and continuum
luminosities correlated with FWHM(H), which may be the trace of their
rapid black hole mass grow. BLS1 do not show such trends. Also, PAHs may be
destroyed as the black hole grows and the starbursts are removed, for NLS1
objects.Comment: Revisiting narrow-line Seyfert 1 galaxies and their place in the
Universe - NLS1 Padov
Tidal variability of the motion in the Strait of Otranto
Various current data, collected in the Strait of Otranto during the period
1994ā2007, have been analysed with the aim of describing the characteristics
of the tidal motions and their contribution to the total flow variance. The
principal tidal constituents in the area were the semi-diurnal (M2) and the
diurnal (K1), with the latter one predominant. The total flow was, in
general, more energetic along the flanks than in the middle of the strait.
Specifically, it was most energetic over the western shelf and in the upper
layer along the eastern flank. In spite of the generally low velocities (a
few cm s<sup>ā1</sup>) of the principal tidal constituents, the tidal variance has
a pattern similar to that of the total flow variance, that is, it was large
over the western shelf and low in the middle. The proportion of non-tidal
(comprising the inertial and sub-inertial low-frequency bands) to tidal flow
variances was quite variable in both time and space. The low-frequency
motions dominated over the tidal and inertial ones in the eastern portion of
the strait during the major part of the year, particularly in the upper and
intermediate layers. In the deep, near-bottom layer the variance was evenly
distributed between the low frequency, diurnal and semi-diurnal bands. An
exception was observed near the western shelf break during the summer season
when the contribution of the tidal signal to the total variance reached
77%. This high contribution was mainly due to the intensification of the
diurnal signal at that location at both upper and bottom current records
(velocities of about 10 cm s<sup>ā1</sup>). Local wind and sea level data were
analysed and compared with the flow to find the possible origin of this
diurnal intensification. Having excluded the sea-breeze impact on the
intensification of the diurnal tidal signal, the most likely cause remains
the generation of the topographically trapped internal waves and the diurnal
resonance in the tidal response. These waves were sometimes generated by the
barotropic tidal signal in the presence of summer stratification and the
strong bottom slope. This phenomenon may stimulate diapycnal mixing during
the stratified season and enhance ventilation of the near-bottom layers
Mass Spectra of Labeled Cyclopentanols
The fragmentation of cyclopentanol has been studied by employing
the deuterium labeling technique. Starting from the molecular
ion the following specific processes could be established:
loss of H from the position 1, loss of CH3 formed mainly from 2
(or 5) position after a-scission, loss of H 2 0 as a 1,3-elimination,
and loss of C2H 5 generated from 2 and 3 or 4 and 5 positions plus
one hydrogen from position 5 or 2, respectively. The results are
discussed
RXJ 0921+4529: a binary quasar or gravitational lens?
We report the new spectroscopic observations of the gravitational lens RXJ
021+4529 with the multi-mode focal reducer SCORPIO of the SAO RAS 6-m
telescope. The new spectral observations were compared with the previously
observed spectra of components A and B of RXJ 0921+4529, i.e. the same
components observed in different epochs. We found a significant difference in
the spectrum between the components that cannot be explained with microlensing
and/or spectral variation. We conclude that RXJ 0921+4529 is a binary quasar
system, where redshifts of quasars A and B are 1.6535 +/- 0.0005 and 1.6625 +/-
0.0015, respectively.Comment: 6 pages, 5 figures, accepted for publication in The Astrophysical
Journal Letter
Spectral Optical Monitoring of the Narrow Line Seyfert 1 galaxy Ark 564
We present the results of a long-term (1999--2010) spectral optical
monitoring campaign of the active galactic nucleus (AGN) Ark 564, which shows a
strong Fe II line emission in the optical. This AGN is a narrow line Seyfert 1
(NLS1) galaxies, a group of AGNs with specific spectral characteristics. We
analyze the light curves of the permitted Ha, Hb, optical Fe II line fluxes,
and the continuum flux in order to search for a time lag between them.
Additionally, in order to estimate the contribution of iron lines from
different multiplets, we fit the Hb and Fe II lines with a sum of Gaussian
components. We found that during the monitoring period the spectral variation
(F_max/F_min) of Ark 564 was between 1.5 for Ha to 1.8 for the Fe II lines. The
correlation between the Fe II and Hb flux variations is of higher significance
than that of Ha and Hb (whose correlation is almost absent). The permitted-line
profiles are Lorentzian-like, and did not change shape during the monitoring
period. We investigated, in detail, the optical Fe II emission and found
different degrees of correlation between the Fe II emission arising from
different spectral multiplets and the continuum flux. The relatively weak and
different degrees of correlations between permitted lines and continuum fluxes
indicate a rather complex source of ionization of the broad line emission
region.Comment: Accepted for publication in ApJ
Changes of the content of biogenic amines during winemaking of Sauvignon wines
The aim of the present work was to study the changes of the content of biogenic amines during winemaking and maturation processes of wines made from Vitis vinifera cv Sauvignon grapes from Slavonia region (vintage 2008). Biogenic amines were quantified using a reversed-phase high performance liquid chromatography (HPLC) with fluorescence detection after pre-column derivatization with o-phthalaldehyde (OPA). Samples used in this study were obtained during production of Sauvignon wines in three different ways in order to produce quality wine (QW), quality press wine (QPW) and macerated wines (MW). The QPW corresponds to the first fraction obtained by direct pressing pomace, while the QW is the free run wine. The MW was obtained by grape mash cryomaceration. Putrescine and tryptamine were the most prevalent amines, followed by histamine, cadaverine and tyramine. The macerated wine posses higher content of biogenic amines than press and free run wines. In all analysed wines the content of biogenic amines tends to increase during winemaking and maturation and the main increase was detected during the malolactic fermentation. The detected content of histamine and tyramine were below the content considered to have an adverse effect on human health
Electrochemical Characterization of Bronze Exposed to Outdoor Atmosphere
The aim of this work was to examine corrosion behaviour of bare and artificial patinated bronzes during exposure to urban outdoor atmosphere. Studies were conducted on copper and two different bronzes in order to evaluate the influence of substrate composition
on patina composition and electrochemical behaviour. Additionally, two different patination methods were compared. Corrosion behaviour was examined using electrochemical impedance spectroscopy with gel-electrolyte electrochemical cell. The composition of patina was determined by ATR-FTIR spectroscopy. The obtained results showed that all studied artificial patinas initially decrease the corrosion resistance of copper and bronzes but in time their corrosion resistance improves, and even for certain combinations, artificial patina-bronze corrosion resistance is higher than that of naturally patinated bronze.
This work is licensed under a Creative Commons Attribution 4.0 International License
UÄinci hiperbariÄnog kisika na vidne funkcije u bolesnika s ishemiÄnom optiÄkom neuropatijom
The effects of hyperbaric oxygen therapy were studied in nine patients with non-arteritic anterior ischaemic optic neuropathy, who had been unsatisfactorily treated with corticosteroids. In four patients with signs of optic disc atrophy there was no improvement of visual functions after hyperbaric oxygen treatment, whereas in the other five patients, who had no signs of optic disc atrophy, visual acuity and visual field improved. The achieved improvements were maintained al a control examination six months later. Results suggest that hyperbaric oxygen might be a new remedy for the selected cases of non-arteritic ischaemic optic neuropathy and call for a controlled clinical study aiming to acurately assess its efficacy.Ispitivani su uÄinci tretmana hiperbariÄnim kisikom u devet bolesnika s nearteritiÄinim oblikom prednje ishemiÄne optikoneuropatije, koji su prethodno lijeÄeni kortikosteroidima bez uspjeha. U Äetiri bolesnika sa znakovima atrofije optiÄkog diska, nakon tretmana hiperbariÄnim kisikom, nije naÄeno nikakvo poboljÅ”anje vidnih funkcija, dok je u ostalih pet, bez znakova atrofije optiÄkog diska, ustanovljeno poboljÅ”anje oÅ”trine vida i vidnog polja. Ova poboljÅ”anja naÄena su i na kontrolnom pregledu nakon Å”est mjeseci. Rezultati ispitivanja sugeriraju hiperbariÄnu oksigenaciju kao moguÄ naÄin lijeÄenja selekcioniranih sluÄajeva nearteritiÄnog oblika ishemiÄne optikoneuropatije, kao i kontrolirani kliniÄki pokus, radi egzaktnijeg utvrÄivanja efikasnosti hiperbariÄne oksigenacije u ovih bolesnika
Anatomy and radiology of the variations of aortic arch branches in 1,266 patients
Background: The most reliable data about arterial variations, which are very important in surgery and radiology, can be obtained from a large series of patients.Materials and methods: We examined angiographic and multislice computerised tomography (MSCT) images in a group of 1,265 patients and in 1 dissected specimen.Results: While in 946 (74.72%) of the patients a normal vascular pattern (type I) was noticed, in the remaining 320 (25.28%) patients variations of the branchesof the aortic arch were found, which were classified into types II through VIII and a few subtypes. Type II (2.84%) comprised a common origin of the left commoncarotid and subclavian arteries. Type III (15.56%) was related to an origin of the left subclavian artery from the brachiocephalic trunk. Type IV (0.55%) includedthe aortic origin of both common carotid and subclavian arteries, with the rightsubclavian artery having a retroesophageal course. Type V (0.24%) included thesame 4 supra-aortic branches, which, however, arose from a double or a right--sided aortic arch. Type VI (3.63%) comprised the aortic origin of the left vertebralartery, type VII (0.24%) the same origin of the right vertebral artery, and type VIII(2.22%) the aortic origin of the thyroideaima artery. A corresponding embryological background and clinical implications of the described aberrant vessels were presented.Conclusions: In more than one quarter of the cases, the branching pattern of the examined arteries did not follow the classical pattern. Detailed knowledge of aortic branch variations is of great significance in anatomy, embryology, andclinical medicine, especially in radiology and thoracic surgery
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