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Stress is unavoidable and essential to cellular and organismal evolution and failure to adapt or restore homeostasis can lead to severe diseases or even death. At the cellular level, stress drives a plethora of molecular changes, of which variations in the profile of protein post-translational modifications plays a key role in mediating the adaptative response of the genome and proteome to stress. In this context, post-translational modification of proteins by ubiquitin-like modifiers, (Ubl), notably SUMO, is an essential stress response mechanism. In this review, aiming to draw universal concepts of the Ubls stress response, we will decipher how stress alters the expression level, activity, specificity and/or localization of the proteins involved in the conjugation pathways of the various type-I Ubls, and how this result in the modification of particular Ubl targets that will translate an adaptive physiological stress response and allow cells to restore homeostasis.

We identified EME1, the regulatory subunit of the structure-specific endonuclease complex EME1-MUS81, as substrate for the sumoylated UBC9 and demonstrated synergistic functions in promoting Camptothecin (CPT)-induced nucleolar ribosomal DNA (rDNA) repair (Nagamalleswari et al, co-submitted). Sumoylation of EME1 appears complex involving mono- and poly-sumoylation. Hence, we addressed here whether these modifications differentially regulate EME1 functions by analyzing EME1-variant expressing cell lines including mono-sumo(1)ylation and poly-sumo(2)ylation mimetic fusions. We complemented our analysis with the regulated endogenous EME1 interactome and our observation that Trichostatin A (TSA) induced EME1 and UBC9 sumoylation. Our findings are substantiated by identifying several regulatory proteins and by detecting CPT-induced endogenous di- and poly-sumoylated EME1 in different cell fractions. Together, our data suggest that Histone H4 acetylation, two mono-sumoylation events, poly-sumoylation, ISG15 and ubiquitination sequentially and in mutual dependence tightly control the intracellular localization, recruitment to DNA lesions, enzymatic activity, withdrawal from DNA lesions and the stability of EME1.

In this paper we discuss different properties of DMP-inverse of a square matrix introduced by Malik and Thome [On a new generalized inverse for matrices of an arbitrary index. Applied Mathematics a...

The upcoming photometric surveys, such as the Rubin Observatory's Legacy Survey of Space and Time (LSST) will monitor unprecedented number of active galactic nuclei (AGN) in a decade long campaign. Motivated by the science goals of LSST, which includes the harnessing of broadband light curves of AGN for photometric reverberation mapping (PhotoRM), we implement the existing formalism to estimate the lagged response of the emission line flux to the continuum variability using only mutli-band photometric light curves. We test the PhotoRM method on a set of 19 artificial light curves simulated using a stochastic model based on the Damped Random Walk process. These light curves are sampled using different observing strategies, including the two proposed by the LSST, in order to compare the accuracy of time-lag retrieval based on different observing cadences. Additionally, we apply the same procedure for time-lag retrieval to the observed photometric light curves of NGC 4395, and compare our results to the existing literature.

We investigate the broad line profiles emitted from a system supermassive binary black hole (SMBBH) having elliptical orbits and low mass ratio of $m_2/m_1\sim 0.1$. Our model assumes a super Eddington accretion flow in the case of a smaller component, whereas the massive component has very small or negligible accretion, therefore supposing that no broad line region (BLR) is attached to it. Thus, the proposed SMBBH system contains one moving BLR, associated with the less massive component and one circum-binary BLR. We study the effect of different total mass of the system (ranging from 10$^6$ to 10$^8$ Solar masses) to the $\mathrm{H\beta}$ line profiles and to the continuum and line light curves. The resulted broad line profiles are asymmetric and shifted, and are varying during the orbital period. The asymmetry in the broad line profiles is discussed in terms of expected differences between the proposed model of the SMBBH with one active component and the scenario of a recoiling black hole. We discuss the periodicity detected in the line and continuum light curves, as well as in the variations of the line asymmetry and shift., Comment: 10 pages, 8 figures, 1 table

Here we present the long-term optical spectral monitoring of a changing-look active galactic nuclei (AGN) NGC 3516 that covers 22 years (from 1996 to 2018). We explore a variability in the broad lines and continuum, finding that the continuum is changing by more than a factor of 2, while the broad lines are varying by more than a factor of 10. The minimum of activity is observed in 2014, when the broad lines almost disappeared. We confirm that NGC 3516 is a changing-look AGN, and the absorption seen in the UV and X-ray may indicate that there is an obscuring region which is responsible for this. The line profiles are also changing. The mean profiles of the broad Halpha and Hbeta lines show shoulder-like structure in the wings, and enhanced peak, that may indicate a complex BLR. The rms-profiles of both lines seem to have the same shape and width of around 4200 km/s, indicating practically the same kinematics in the Halpha and Hbeta emitting regions. Measured time-lags between the continuum and Halpha and Hbeta broad-line variability are ~15 and 17 days, respectively, that in combination with the broad lines width allows us to estimate the NGC 3516 central black hole mass. We find that the black hole mass is 4.73+-1.40 x 10^7M_sun which is in agreement with previous estimates.

We present the variability study of the lowest-luminosity Seyfert 1 galaxy NGC 4395 based on the photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC 4395 with a $\sim$5 minute cadence during a period of 10 days and obtained light curves in the UV, V, J, H, and K/Ks bands as well as the H$\alpha$ narrow-band. The RMS variability is $\sim$0.13 mag on \emph{Swift}-UVM2 and V filter light curves, decreasing down to $\sim$0.01 mag on K filter. After correcting for continuum contribution to the H$\alpha$ narrow-band, we measured the time lag of the H$\alpha$ emission line with respect to the V-band continuum as ${55}^{+27}_{-31}$ to ${122}^{+33}_{-67}$ min. in 2017 and ${49}^{+15}_{-14}$ to ${83}^{+13}_{-14}$ min. in 2018, depending on the assumption on the continuum variability amplitude in the H$\alpha$ narrow-band. We obtained no reliable measurements for the continuum-to-continuum lag between UV and V bands and among near-IR bands, due to the large flux uncertainty of UV observations and the limited time baseline. We determined the AGN monochromatic luminosity at 5100\AA\ $\lambda L_\lambda = \left(5.75\pm0.40\right)\times 10^{39}\,\mathrm{erg\,s^{-1}}$, after subtracting the contribution of the nuclear star cluster. While the optical luminosity of NGC 4395 is two orders of magnitude lower than that of other reverberation-mapped AGNs, NGC 4395 follows the size-luminosity relation, albeit with an offset of 0.48 dex ($\geq$2.5$\sigma$) from the previous best-fit relation of Bentz et al. (2013)., Comment: Accepted for publication in ApJ (Feb. 23rd, 2020). 18 pages, 10 figures

Introduction. Protocols and guidelines have been improving results of our clinical practice. Sometimes there have been differences between guidelines on the same topic, but they have not been so important usually. As far as the start of vitamin K antagonists (VKA) in a non-high risk pulmonary thromboembolism (PTE) patients is concerned, there is global consensus (reflected in all comprehensive guidelines) that it should be on the admission day or a day later. However, there are situations in which this VKA administering from the first (or second) day of hospitalization may actually complicate the treatment. Case report. As an illustration, our female, 71 years old patient with second unprovoked, intermediate-high risk PTE was given low-molecular-weight heparin (LMWH) + VKA from the second day. Due to lack of improvement in symptoms, oxygen saturation and D dimer after 9 days, computed tomography pulmonary angiography (CTPA) was repeated and it confirmed minimal advancement. The patient already had achieved target international normalized ratio (INR) and it complicated proceeding to fibrinolytic therapy. Conclusion. Correction of the therapeutic approach in the PTE treatment may be needed even if the treatment is completely conducted according to the latest guidelines. We recommend postponing VKA from the first (or second) day of hospitalization (as suggested in all available guidelines for non-high risk PTE patients) until satisfying clinical improvement is reached.

The active galactic nuclei (AGN) are among the most powerful sources with an inherent, pronounced and random variation of brightness. The randomness of their time series is so subtle as to blur the border between aperiodic fluctuations and noisy oscillations. This poses challenges to analysing of such time series because neither visual inspection nor pre-exisitng methods can identify well oscillatory signals in them. Thus, there is a need for an objective method for periodicity detection. Here we review our a new data analysis method that combines a two-dimensional correlation (2D) of time series with the powerful methods of Gaussian processes. To demonstrate the utility of this technique, we apply it to two example problems which were not exploited enough: damped rednoised artificial time series mimicking AGN time series and newly published observed time series of changing look AGN (CL AGN) NGC 3516. The method successfully detected periodicities in both types of time series. Identified periodicity of $\sim 4$ yr in NGC 3516 allows us to speculate that if the thermal instability formed in its accretion disc (AD) on a time scale resembling detected periodicity then AD radius could be $\sim 0.0024$ pc., Comment: accepted by Open astronomy

A new combined data of 5 well known type 1 AGN are probed with a novel hybrid method in a search for oscillatory behavior. Additional analysis of artificial light curves obtained from the coupled oscillatory models gives confirmation for detected periods that could have physical background. We find periodic variations in the long-term light curves of 3C 390.3, NGC 4151, NGC 5548 and E1821+643, with correlation coefficients larger than 0.6. We show that oscillatory patterns of two binary black hole candidates NGC 5548 and E1821+643 corresponds to qualitatively different dynamical regimes of chaos and stability, respectively. We demonstrate that absence of oscillatory patterns in Arp 102B could be due to a weak coupling between oscillatory mechanisms. This is the first good evidence that 3C 390.3 and Arp 102B, categorized as double-peaked Balmer line objects, have qualitative different dynamics. Our analysis shows a novelty in the oscillatory dynamical patterns of the light curves of these type 1 AGN.

Over the last decades, time domain heart rate (HR) variability analysis has been explored in different pediatric clinical settings to obtain information on the cardiac autonomic tone. However, the consistency over time of 24 h time domain HRV measurements in children is not well-known. We investigated the reproducibility of 24 h HRV time-domain indices (1 day apart), from 39 healthy children (9.5 ± 5.3 years, 56.4% girls). The parameters analysed included: standard deviation of all the adjacent NN intervals, standard deviation of the averages of NN intervals (the intervals between normal R-peaks) in all 5-min segments, and square root of the mean of the sum of the squares of the differences between adjacent NN intervals, uncorrected and corrected for HR. Reproducibility between two 24-h ECG recordings was evaluated by intraclass correlation coefficients, standard error of measurement, coefficients of variation and Bland–Altman plots. For the analyzed time-domain indices, standard deviation of all the adjacent NN intervals corrected for HR showed best reproducibility with the highest intraclass correlation coefficient (0.987), the lowest coefficients of variation (5.5%) and the best level of agreement between two recordings as assessed by Bland–Altman plots. Our results indicate that the standard deviation of all the adjacent NN intervals corrected for the HR parameter obtained from 24-h ambulatory recordings in children is consistent and reproducible over time, thus allowing reliable identification of cardiac autonomic tone in this age group.

Introduction. Eclampsia, serious complication of preeclampsia, can further be complicated by intracranial haemorrhage. Cesarean section under general anesthesia represents an additional risk factor. Case report. We present a case of 22 years old primipara in the 38th gestational week who after a sudden occurrence of a headache, within one hour developed eclampsia. Emergent Caesarean section was undertaken; she was intubated after several attempts. Severe tongue and hypopharyngeal edema and haemathoma made the extubation impossible; she remained intubated, sedated, mechanically ventilated, on antioedematous, anticonvulsive, antihypertensive therapy. On the third postoperative day, tracheostomy was performed. On the sixth day, she complained of a headache and visual disturbances. Neurological examination revealed left-sided hemiparesis. Multislice computed tomography showed intracranial hemorrhage. It was not until the closure of tracheostoma (eleventh day) that her blood pressure normalized and the headache ceased. Four days later she was dismissed from the hospital with improved clinical state. Conclusion. In order to avoid sudden and unexpected, but serious complications of preeclampsia/eclampsia, we emphasize the need of searching for more subtle signs of the disease, of prompt radiologic diagnosis and aggressive blood pressure control, with a prepared strategy for difficult airway management.

The small ubiquitin-related modifier (SUMO) is a protein of ~10kDa that is covalently conjugated to its substrate proteins in anenzymatic processcalledsumoylation. Thisposttranslational modificationis an essential regulatory mechanism that plays crucial roles in many cellular pathways. It allows rapid adaptation to environmental changes by switching protein functions due to alternate complex assemblies, changes in intracellular localization,enzymatic activity, or stability. SUMO conjugation is executed by the hierarchical action of E1, E2, and E3 enzymes. Both E2 and E3 enzymes contribute tosubstrate specificitybut with E3ligasesbeing the more important for this. E1 and E2 activities are essential for all sumoylation reactions but usually—with a few exceptions—modify substrates only inefficiently. Hence, most substrates require the additional action of an E3ligaseor a cofactor. Here, we describe methods to distinguish a bona fide E3 ligase from a cofactor activity by using in vitro sumoylation assays.

In this paper we present new optical observations of the galaxy NGC 185 intended to reveal the status of supernova remnants (SNRs) in this dwarf companion of the Andromeda galaxy. Previously, it was reported that this galaxy hosts one SNR. Our deep photometric study with the 2m telescope at Rozhen National Astronomical Observatory using narrow-band H$\alpha$ and [SII] filters revealed complex structure of the interstellar medium in the center of the galaxy. To confirm the classification and to study the kinematics of the detected nebulae, we carried out spectroscopic observations using the SCORPIO multi-mode spectrograph at the 6m telescope at the Special Astrophysical Observatory of the Russian Academy of Science, both in low- and high-resolution modes. We also searched the archival X-ray and radio data for counterparts of the candidate SNRs identified by our optical observations. Our observations imply the presence of one more SNR, one possible HII region previously cataloged as part of an SNR, and the presence of an additional source of shock ionization in one low-brightness PN. We detected enhanced [SII]/H_alpha and [NII]/H_alpha line ratios, as well as relatively high (up to 90 km s$^{-1}$) expansion velocities of the two observed nebulae, motivating their classification as SNRs (with diameters of 45 pc and 50 pc), confirmed by both photometric and spectral observations. The estimated electron density of emission nebulae is 30 - 200 cm$^{-3}$. Archival XMM-Newton observations indicate the presence of an extended, low-brightness, soft source in projection of one of the optical SNRs, whereas the archival VLA radio image shows weak, unresolved emission in the center of NGC 185., Comment: 15 pages, 14 figures, accepted for publication in A&A

We present observations from the short-term intensive optical campaign (from Sep2019 to Jan2020) of the changing-look Seyfert NGC 3516. This active galactic nucleus is known to have strong optical variability and has changed its type in the past. It has been in the low-activity state in the optical since 2013, with some rebrightening from the end of 2015 to the beginning of 2016, after which it remained dormant. We aim to study the photometric and spectral variability of NGC 3516 from the new observations in U- and B-bands and examine the profiles of the optical broad emission lines in order to demonstrate that this object may be entering a new state of activity. NGC 3516 has been monitored intensively for the past 4 months with an automated telescope in U and B filters, enabling accurate photometry of 0.01 precision. Spectral observations were triggered when an increase in brightness was spotted. We support our analysis of past-episodes of violent variability with the UV and X-ray long-term light curves constructed from the archival Swift data. An increase of the photometric magnitude is seen in both U and B filters to a maximum amplitude of 0.25mag and 0.1 mag, respectively. During the flare, we observe stronger forbidden high-ionization iron lines than reported before, as well as the complex broad Ha and Hb lines. This is especially seen in Ha which appears to be double-peaked. It seems that a very broad component of ~10,000 km/s in width in the Balmer lines is appearing. The trends in the optical, UV, and X-ray light curves are similar, with the amplitudes of variability being significantly larger in the case of UV and X-ray bands. The increase of the continuum emission, the variability of the coronal lines, and the very broad component in the Balmer lines may indicate that the AGN of NGC 3516 is finally leaving the low-activity state in which it has been for the last ~3 years., 7 pages, 6 figures, accepted in A&A (corrected after receiving comments from the language editor)

Recurrent abdominal pain (RAP) in children is defined as at least three episodes of pain that occur over at least three months and affect the child's ability to perform normal activities. The prevalence of recurrent abdominal pain in a population of schoolchildren varies from 10% to even 45%. Pituitary disorders are rarely considered as causative factor in children with abdominal pain, especially in absence of midline facial defects and in case of emergency, when growth monitoring is neglected or not performed carefully. Herein we report an unusual case of RAP caused by secondary adrenal insufficiency. An 8-year-old girl was hospitalized repeatedly because of RAP. Biological parameters including white blood cell count, hemoglobin value, C-reactive protein, glucose, electrolytes were within the normal range. Low cortisol combined with low ACTH values was the clue for diagnosis. The magnetic resonance imaging (MRI) of the pituitary region revealed anterior pituitary hypoplasia and pituitary stalk interruption. To the best of our knowledge, this is the first report of child with RAP caused by pituitary disorder. Possible inherited, autoimmune and post-traumatic causative factors are discussed.

The photometric light curve of PG1302-102 shows periodic variability which makes this object one of the most plausible supermassive black hole binary candidate. Interestingly, the most recent study of its updated optical light curve reports a decrease in significance of periodicity which may suggest that the binary model is less favorable. Here, we model the PG 1302-102 light curve, spanning almost 20 years, with a supermassive black hole binary system in which a perturbation in the accretion disk of more massive component is present. Our model reproduces well the observed light curve with a slight perturbation of a sinusoidal feature and predicts that a slightly larger period than previously reported, of about 1899 days, could arise due to a cold spot in the disk of {\bf more massive} component of a close, unequal-mass ($\frac{\mathrm{m}_{1}}{\mathrm{m}_{2}}=0.1$) black hole binary system. The light curve resembles the pattern of sinusoid-like shape within a few years, which could be confirmed by future observations. In addition, using our hybrid method for periodicity detection, we show that the periods in the observed ($1972\pm 254$ days) and modeled ($1873 \pm \ 250$ days) light curves are within one-sigma, which is also consistent with our physical model prediction and with previous findings. Thus, both the periodic nature and its slight fluctuation of the light curve of PG1302-102 is evident from our physical model and confirmed by the hybrid method for periodicity detection., Accepted to ApJ

The main purpose of this paper is to investigate inequalities on symmetric sums of diagonalizable and positive definite tensors. In particular, we generalize the well-known Hlawka and Popoviciu inequalities to the case of diagonalizable and positive definite tensors. As corollaries, we extend Hlawka and Popoviciu inequalities for the combinatorial determinant, permanent and immanant of tensors, and generalized tensor functions.

The intrinsic Baldwin effect is an anti-correlation between the line equivalent width and the flux of the underlying continuum detected in a single variable active galactic nucleus (AGN). This effect, in spite of the extensive research, is still not well understood, and might give us more information about the physical properties of the line and continuum emission regions in AGNs. Here we present preliminary results of our investigation of the intrinsic Baldwin effect of the broad H$\beta$ line in several Narrow-line Seyfert 1 (NLSy 1) galaxies, for which data were taken from the long-term monitoring campaigns and from the Sloan Digital Sky Survey Reverberation Mapping project.

PURPOSE High-fructose consumption and chronic stress are both associated with metabolic inflammation and insulin resistance. Recently, disturbed activity of energy sensor AMP-activated protein kinase (AMPK) was recognized as mediator between nutrient-induced stress and inflammation. Thus, we analyzed the effects of high-fructose diet, alone or in combination with chronic stress, on glucose homeostasis, inflammation and expression of energy sensing proteins in the rat liver. METHODS In male Wistar rats exposed to 9-week 20% fructose diet and/or 4-week chronic unpredictable stress we measured plasma and hepatic corticosterone level, indicators of glucose homeostasis and lipid metabolism, hepatic inflammation (pro- and anti-inflammatory cytokine levels, Toll-like receptor 4, NLRP3, activation of NFκB, JNK and ERK pathways) and levels of energy-sensing proteins AMPK, SIRT1 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α). RESULTS High-fructose diet led to glucose intolerance, activation of NFκB and JNK pathways and increased intrahepatic IL-1β, TNFα and inhibitory phosphorylation of insulin receptor substrate 1 on Ser307. It also decreased phospho-AMPK/AMPK ratio and increased SIRT1 expression. Stress alone increased plasma and hepatic corticosterone but did not influence glucose tolerance, nor hepatic inflammatory or energy-sensing proteins. After the combined treatment, hepatic corticosterone was increased, glucose tolerance remained preserved, while hepatic inflammation was partially prevented despite decreased AMPK activity. CONCLUSION High-fructose diet resulted in glucose intolerance, hepatic inflammation, decreased AMPK activity and reduced insulin sensitivity. Chronic stress alone did not exert such effects, but when applied together with high-fructose diet it could partially prevent fructose-induced inflammation, presumably due to increased hepatic glucocorticoids. This is a post-peer-review, pre-copyedit version of an article published in European Journal of Nutrition. The final authenticated version is available online at: [http://dx.doi.org/10.1007/s00394-018-1730-1]

Hemorrhage volume, level of consciousness and ventricular extension and expansion of the hematoma are prognostic factors for clinical outcome of intracerebral hemorrhage (ICH). Volumetric measurement of ICH has an important clinical and prognostic meaning. The aim of this study was to compare the methods which are being used to measure ICH volume: the ABC/2 method and semiautomated method with computer volumetric program. Our study represents a retrospective analisys of 54 patients (61.11% male and 38.89% female patients with mean age 67.20±10.30 years) who underwent computed tomography (CT) scan of endocranium. Volumetric measurements were performed by ABC/2 method and computer semiautomated method with volumetric program on Аdvantage Windows 3D Workstation 4.1. Mean value and standard deviation obtained by ABC/2 method were 41.98±35.47, while mean value and standard deviation obtained by computer semiautomated method with volumetric program were 52.12±45.61. There is a statistically significant difference between the values obtained by these two methods (p=0.03). The absolute difference was 10.14 cm. The values acquired by computer method were by 19.46% higher than those acquired by formula. There is a statstically strong positive correlation between these two methods (r=0.852, p

Purpose Although pancreatic cancer is a common malignancy, signet ring cell carcinoma of the pancreas is a very rare histologic type with only 6 cases reported so far. We present a patient with primary signet ring cell carcinoma of the pancreas and a good response to neoadjuvant chemotherapy. Case report A 67-year-old woman presented at a regional hospital with a 2-week history of painless progressive jaundice. Abdominal computed tomography showed a tumor in the head of the pancreas, 4.5 cm in largest diameter. Since endoscopic biopsy and biliary stenting were not available, the patient had undergone palliative choledochoduodenostomy and tru-cut needle biopsy of the lesion. Histopathology revealed primary signet ring cell carcinoma of the pancreas. The tumor was considered borderline resectable and 3-month neoadjuvant chemotherapy with gemcitabine alone was administered due to the low creatinine clearance rates. Follow-up abdominal scan demonstrated very good response to chemotherapy and significant tumor regression to 1.5 cm in largest diameter. Radical cephalic duodenopancreatectomy was performed. Conclusion Significant tumor downsizing in our patient clearly demonstrates good response to neoadjuvant gemcitabine monotherapy. The optimal preoperative chemotherapy leading to tumor reduction and disease control in patients with borderline resectable and locally advanced pancreatic carcinoma is controversial, necessitating further randomized studies including combined chemoradiotherapy and multidrug combination regimens.

Here we present an in-depth analysis of the periodicity of the continua and broad emission lines of a quasar E1821+643. We applied non-parametric composite models, the linear sum of stationary and non-stationary Gaussian processes, and quantified contribution of their periodic parts. We found important qualitative differences among the three periodic signals. Periods of $\sim 2200$ and $\sim 4500$ days appear in both continua 5100 \AA \, and 4200 \AA \,, as well as in the H$\gamma$ emission line. Their integer ratio is nearly harmonic $\sim \frac{1}{2}$, suggesting the same physical origin. We discuss the nature of these periods, proposing that the system of two objects in dynamically interaction can be origin of two largest periods., Comment: accepted for publication in Astrophysics and Space Science,13 pages, 6 figures

The problem of finding the generalized inverse of a product of matrices led to the investigation of the so-called “reverse order law”.

We present the results of the long-term (20-year period, from 1996 to 2015) optical spectral monitoring of the Seyfert 1 galaxy NGC 7469. The variation in the light-curves of the broad He II {\lambda}4686A H{\beta} and H{\alpha} lines, and the continuum at 5100A and 6300A have been explored. The maximum of activity was in 1998, and the variability in the continuum and lines seems to have two periods of around 1200 and 2600 days, however these periodicities should be taken with caution because of the red-noise. Beside these periods, there are several short-term (1-5 days) flare-like events in the light-curves. There are good correlations between the continuum fluxes and H{\alpha} and H{\beta} line fluxes, but significantly smaller correlation between the He II and continuum. We found that the time-lags between the continuum and broad lines are different for H{\beta} (~20 l.d.) and H{\alpha} (~3 l.d.), and that He II also has a smaller lag (~2-3 l.d.). The H{\alpha} and H{\beta} line profiles show a slight red asymmetry, and the broad line profiles did not changed in the 20-year period. Using the lags and widths of H{\alpha} and H{\beta} we estimated the central black hole mass and found that it is ~(1-6)x$10^7 M_{\odot}$, which is in agreement with previous reverberation estimates., Comment: Accepted in Monthly Notices of the Royal Astronomical Society

The concept of generalized inverses seems to have been first mentioned in print in 1903 by Fredholm [1] who formulated a pseudoinverse for a linear integral operator which is not invertible in the ordinary sense.

In this section we will discuss various problems of completions of operator matrices and present an application of such results to some problems concerning generalized inverses and to that of invertibility of linear combinations of operators.

The problem of finding representations of the Drazin inverse of a \(2\times 2\) block matrix is of great significance primarily due to its applications in solving systems of linear differential equations, linear difference equations [1, 2, 3, 4] and perturbation theory of the Drazin inverse [5, 6, 7].

It is becoming clear that we can define two different types of nearby AGN belonging to the Seyfert 1 class (S1), on the basis of the match of the intensities of their Broad Balmer Lines (BBL) with the Boltzmann Plots (BP). These two types of S1 galaxies, that we call BP-S1 and NoBP-S1, are characterized, in first approximation, by Broad Line Regions (BLR) with different structural and physical properties. In this communication, we show that these features can be well pointed out by a multi-wavelength analysis of the continuum and of the broad recombination Hydrogen lines, that we carry out on a sample of objects detected at optical and X-ray frequencies. The investigation is addressed to verify whether BP-S1 are the ideal candidates for the study of the kinematical and structural properties of the BLR, in order to derive reliable estimates of the mass of their central engine and to constrain the properties of their nuclear continuum spectrum., Comment: 26 pages, 4 figures (1 multi-paged). Accepted for publication on Advances in Space Research. Contribution to the IX SCSLSA

Here we present an analysis of spectro-polarimetric observations of type 1.5 AGN Mrk 6, performed with 6m telescope SAO RAN in 12 epochs (2010 -- 2013). Additionally, the inter-stellar mater (ISM) polarization has been observed and its contribution to the AGN spectral polarization is taken into account. We measured Stokes parameters and determined the polarization parameters in 12 spectra with and without correction for the ISM polarization. We estimated the time lag between the unpolarized and polarized continuum flux variation of about ~2 days, that indicates a compact scattering region which contributes to the polarized continuum variability. The polarization in H{\alpha} is complex, showing three prominent components in the BLR, one redshifted around +3000 km/s that corresponds to the red shoulder in H{\alpha}, and two blue-shifted around -2000 km/s and -6000 km/s. We found that the ISM polarization has a very significant influence on the measured AGN polarization parameters. After correcting the observations for the ISM polarization we were able to detect the Keplerian motion in the BLR. We give a new method for the black hole mass estimation using spectro-polarimetric observation in the line profile, finding the black hole mass in Mrk 6 of $M_{BH} \sim 1.53 \cdot 10^8 M_{\odot}$, that is in a good agreement with reverberation estimates., Comment: Version submitted to MNRAS, after minor revision

Cephalometry is a measurement of the head by imaging, also taking into account the layer which consists of all the soft tissues of the head. Following the introduction of computed tomography (CT), 3D reconstruction of the head and neck structures and 3D analysis of angular and linear cephalometric parameters was enabled. This study aimed to determine the characteristic cephalometric parameters, using the 2D reconstruction of the multi-slice CT (MSCT) images, which are essential for computer designing of the parametric-geometric-mathematical model (PGMM) of the human skull. We conducted the study on 20 CT scans of adult patients (12 males and 8 females), taken from the radiology archive of the Clinical Center in Niš. Measurements were done on 2D reconstruction images of preselected 3D images of the human head created using MSCT. The values of 29 linear cephalometric parameters (LCP) and 20 angular cephalometric parameters (ACP) were determined. Statistically significant differences between males and females were noted for the distance between the points Sella and Supraorbitale and for the distance between the points Subspinale and Labium superius. Mean values of cephalometric parameters obtained by measurements on 2D CT images can be used to generate normative parameters which represent values used to generate 3D PGMM of the human skull. This PGMM of the skull may allow a more accurate diagnosis, better selection of treatment methods and more accurate prognosis for healing in orthodontics, implantology, oral and maxillofacial surgery.

Introduction. Fetal tumors are relatively rare and the early prenatal diagnosis enables the prediction of possible complications and decision for appropriate treatment. This paper deals with the role of ultrasonography and magnetic resonance imaging in the early prenatal diagnosis of sacrococcygeal teratoma. Case report. A 21-year-old primigravida was found to have a large sacrococcygeal tumor measuring 25x30mm, presented mainly as a solid mass, when she underwent the initial ultrasound examination on the first day of 19th week of gestation. There were no other associated anomalies. The second ultrasound examination was obtained after 6 days and revealed that the tumor had doubled its size. The prominent enlargement raised suspicion of immature sacrococcygeal teratoma and thus, fetal magnetic resonance imaging was performed in the 20th gestation week. The examination showed a crococcygeal teratoma presented as a large solid mass with small microcystic areas, the largest diameter being 60mm, completely externally positioned with no intra-pelvic extension. Rapid tumor growth posed a threat to the fetal circulation and it was the main reason when opting for the termination of pregnancy at 20 weeks of gestation. Pathohystological examination confirmed the diagnosis of immature sacrococcygeal teratoma. Discussion. In the prenatal period the magnetic resonance imaging of a fetal tumor initially diagnosed by ultrasound examination is an additional part of diagnostic procedure, and it is not contraindicated during pregnancy. Magnetic resonance imaging improves the delineation of the tumor. The prompt prenatal diagnosis of sacrococcygeal teratoma, as well as the detection of possible associated anomalies, is important for the pregnancy management, prediction of possible complications and choice of appropriate treatment. Conclusion. Ultrasonography and magnetic resonance imaging are noninvasive, compatible and complementary diagnostic modalities in evaluation of sacrococcygeal teratoma in prenatal period.

We investigate the virilization of the emission lines Hbeta and Mg II in the sample of 287 Type 1 Active Galactic Nuclei taken from the Sloan Digital Sky Survey database. We explore the connections between the intrinsic line shifts and full widths at different levels of maximal intensity. We found that: (i) Hbeta seems to be a good virial estimator of black hole masses, and an intrinsic redshift of Hbeta is dominantly caused by the gravitational effect, (ii) there is an anti-correlation between the redshift and width of the wings of the Mg II line, (iii) the broad Mg II line can be used as virial estimator only at 50% of the maximal intensity, while the widths and intrinsic shifts of the line wings can not be used for this purpose., Comment: 24 pages, 8 figures, 4 tables, accepted in Astrophysics and Space Science

We report the results of the first long-term (1990-2014) optical spectro-photometric monitoring of a binary black hole candidate QSO E1821+643, a low-redshift high-luminosity radio-quiet quasar. In the monitored period the continua and H$\gamma$ fluxes changed for around two times, while the H$\beta$ flux changed around 1.4 times. We found the periodical variations in the photometric flux with the periods of 1200, 1850 and 4000 days, and 4500 days periodicity in the spectroscopic variations. However, the periodicity of 4000-4500 days covers only one cycle of variation and should be confirmed with a longer monitoring campaign. There is an indication of the period around 1300 days in the spectroscopic light curves, but with small significance level, while the 1850 days period could not be clearly identified in the spectroscopic light curves. The line profiles have not significantly changed, showing an important red asymmetry and broad line peak redshifted around +1000 km s$^{-1}$. However, H$\beta$ shows broader mean profile and has a larger time-lag ($\tau\sim120$ days) than H$\gamma$ ($\tau\sim60$ days). We estimate that the mass of the black hole is $\sim2.6\times10^9\rm M_\odot$. The obtained results are discussed in the frame of the binary black hole hypothesis. To explain the periodicity in the flux variability and high redshift of broad lines we discuss a scenario where dense gas-rich cloudy-like structures are orbiting around a recoiling black hole., Comment: Accepted in ApJS

nema

We present observations of the H I tidal arm near a dwarf galaxy NGC 3077 (member of the M81 galaxy group) in the narrow-band [S II] and Hα filters. Observations were carried out in 2011 March with the 2 m RCC telescope at the NAO Rozhen, Bulgaria. Our search for possible supernova remnant candidates (identified as sources with enhanced [S II] emission relative to their Hα emission) in this region yielded no sources of this kind. Nevertheless, we found a number of objects with significant Hα emission that probably represent uncatalogued, low brightness H II regions.

We present observations of the nearby tidal dwarf galaxy Holmberg IX in M81 galaxy group in narrow band [SII] and H$\alpha$ filters, carried out in March and November 2008 with the 2m RCC telescope at NAO Rozhen, Bulgaria. Our search for resident supernova remnants (identified as sources with enhanced [SII] emission relative to their H$\alpha$ emission) in this galaxy yielded no sources of this kind, besides M&H 10-11 or HoIX X-1. Nevertheless, we found a number of objects with significant H$\alpha$ emission that probably represent uncatalogued HII regions., Comment: 8 pages, 5 figures

In this note, the ( p , q ) outer generalized inverse in Banach algebra is considered, a new representation based on the (1, 5) inverse is presented. Also, we construct an iterative method for computing the ( p , q ) outer generalized inverse in Banach algebra.

We present an extended analysis of the relation between radio surface brightness and diameter -- the so-called $\Sigma-D$ relation for planetary nebulae (PNe). We revise our previous derivation of the theoretical $\Sigma-D$ relation for the evolution of bremsstrahlung surface brightness in order to include the influence of the fast wind from the central star. Different theoretical forms are derived: $\Sigma \propto D^{-1}$ for the first and second phases of evolution and $\Sigma\propto D^{-3}$ for the final stage of evolution. Also, we analyzed several different Galactic PN samples. All samples are influenced by severe selection effects, but Malmquist bias seems to be less influential here than in the supernova remnant (SNR) samples. We derived empirical $\Sigma-D$ relations for 27 sample sets using 6 updated PN papers from which an additional 21 new sets were extracted. Twenty four of these have a trivial form of $\beta \approx 2$. However, we obtain one empirical $\Sigma-D$ relation that may be useful for determining distances to PNe. This relation is obtained by extracting a recent nearby (< 1 kpc) Galactic PN sample.

An analysis of the relation between radio surface brightness and diameter, so-called Sigma-D relation, for planetary nebulae (PNe) is presented: i) the theoretical Sigma-D relation for the evolution of bremsstrahlung surface brightness is derived; ii) contrary to the results obtained earlier for the Galactic supernova remnant (SNR) samples, our results show that the updated sample of Galactic PNe does not severely suffer from volume selection effect - Malmquist bias (same as for the extragalactic SNR samples) and; iii) we conclude that the empirical Sigma-D relation for PNe derived in this paper is not useful for valid determination of distances for all observed PNe with unknown distances., 4 pages, 2 figures