Pulsations and Long-Term Light Variability of Three Candidates to Protoplanetary Nebulae

We present new photometric data and analysis of the long-duration UBV photoelectric observations for three candidates to protoplanetary objects - F-supergiants with IR-excesses located at large galactic latitudes, IRAS 18095+2704, IRAS 19386+0155, and IRAS 19500-1709. All three stars have revealed quasiperiodic low-amplitude variabilities caused by pulsations observed against the long-term trends of brightnesses. For IRAS 18095+2704=V887 Her we have found a pulsation period of 109 days and a linear trend of brightness under the constant colours if being averaged over the year timescale. The light curve of IRAS 19386+0155=V1648 Aql over 2000-2008 can be approximated by a wave with a main period of 102 days which is modulated by close frequency, with a period of 98 days, that results in brightness oscillations with a variable amplitude. V1648 Aql has also shown synchronous reddening together with a persistent rise of brightness in the V-band. IRAS 19500-1709=V5112 Sgr experiences irregular pulsations with the periods of 39 and 47 days. The long-term component of the variability of V5112 Sgr may be related to the binary character of this star.Comment: 11 pages, 6 figures, accepted for publication in Pis'ma Astron. Z

Variability of Hot Supergiant IRAS 19336-0400 in the Early Phase of its Planetary Nebula Ionization

We present photoelectric and spectral observations of a hot candidate proto-planetary nebula - early B-type supergiant with emission lines in spectrum - IRAS 19336-0400. The light and color curves display fast irregular brightness variations with maximum amplitudes Delta V=0.30 mag, Delta B=0.35 mag, Delta U=0.40 mag and color-brightness correlations. By the variability characteristics IRAS 19336-0400 appears similar to other hot proto-planetary nebulae. Based on low-resolution spectra in the range lambda 4000-7500 A we have derived absolute intensities of the emission lines H_alpha, H_beta, H_gamma, [SII], [NII], physical conditions in gaseous nebula: n_e=10^4 cm^{-3}, T_e=7000 \pm 1000 K. The emission line H_alpha, H_beta equivalent widths are found to be considerably variable and related to light changes. By UBV-photometry and spectroscopy the color excess has been estimated: E_{B-V}=0.50-0.54. Joint photometric and spectral data analysis allows us to assume that the star variability is caused by stellar wind variations.Comment: 11 pages, 6 figures, 2 tables, accepted for publication in Pis'ma Astron. Zh. (Astronomy Letters

Modeling the spectrum of V4334 Sgr (Sakurai's Object)

Theoretical spectral energy distributions were computed for a grid of hydrogen-deficient and carbon-rich model atmospheres of T(eff) in the range of 5000-6250 K and log g = 1.0 - 0.0 by the technique of opacity sampling, taking into account continuous, molecular band and atomic line absorption. These energy distributions were compared with the spectrum of V4334 Sgr (Sakurai's object) of April, 1997 in the wavelength interval 300-1000 nm. We show that (1) the shape of the theoretical spectra depends strongly on T(eff) but only very weakly on the hydrogen abundance; (2) the comparison of the observed and computed spectra permits to estimate T(eff) approximately 5500 K for V4334 Sgr in April, 1997, and its interstellar reddening (plus a possible circumstellar contribution) E(B-V) approximately 0.70.Comment: 7 pages, 8 figures, LaTeX, accepted by Astronomy and Astrophysic

Pairing of applicants’ CJM with university profile in digital environment as a management task

The work is devoted to the application of the Customer Journey Map (CJM) for university applicants and managerial tasks of adapting the profile of the university in the digital environment to the trajectories of the consumer. The author’s definition of the “profile of the university in the digital environment” concept is offered, the analysis of statistical data of university websites is made. The combination of classical studies of applicants’ motivation and factors influencing enrollment in a particular university with modern methods of studying consumer behavior in the digital environment allows to increase the effectiveness of the admission campaign. Customer Journey Map as an analysis tool, in conjunction with the data of network traffic allows to optimize all types of communications of the university and provide its management with necessary information when making managerial decisions. The research revealed an insignificant influence of the university social networks and thematic groups on the decision to enroll to a particular university, which what caused a deeper study of visitors’ behavior on the university websites. Internet traffic activity for a number of universities was assessed as direct requests, through search services, social networks, mail servers, as well as through referral links, and advertising traffic. The study showed that search engines and direct queries gave the maximum value for traffic. But the effectiveness of advertising to attract applicants is rather low, which indicates the insignificant role of university advertising and confirms the data of the survey in the construction of the Customer Journey Map

Peculiarities and variations in the optical spectrum of the post-AGB star V448Lac=IRAS22223+4327

Repeated observations with high spectral resolution acquired in 1998-2008 are used to study the temporal behavior of the spectral line profiles and velocity field in the atmosphere and circumstellar envelope of the post-AGB star V448Lac. Asymmetry of the profiles of the strongest absorption lines with low-level excitation potentials less 1eV and time variations of these profiles have been detected, most prominently the profiles of the resonance lines of BaII, YII, LaII, SiII. The peculiarity of these profiles can be explained using a superposition of stellar absorption line and shell emission lines. Emission in the (0;1) 5635A Swan band of the C2 molecule has been detected in the spectrum of V448Lac for the first time. The core of the Halpha line displays radial velocity variations with an amplitude ~8 km/s. Radial velocity variations displayed by weakest metallic lines with lower amplitudes, 1-2 km/s, may be due to atmospheric pulsations. Differential line shifts, 0 -- 8 km/s, have been detected on various dates. The position of the molecular spectrum is stationary in time, indicating a constant expansion velocity of the circumstellar shell, Vexp=15.2 km/s, as derived from the C2 and NaI lines.Comment: 19 pages, 8 figures, 1 tabl

Immunoglobulins and predicted mortality in clinical course of concomitant HIV and TB infection

A search for prognostic markers of HIV and tuberculosis coinfection (HIV/TB), especially in case of Mycobacterium tuberculosis multidrug resistance (MDR MBT) associated with low rates of TB eradication, is of relevance in connection with the problem of choosing adequate anti-TB therapy which is able to decrease mortality. 113 HIV/TB patients aged 24 to 58 years were examined: 70 males and 43 females hospitalized at the Novokuznetsk TB Clinic during the 2017—2019 period. MDR MBT (concomitant resistance to Isoniazid and Rifampicin) was found in 50 patients (12 patients with MDR MBT had additional resistance to Fluoroquinolones) aged 24 to 54 years — 31 males and 19 females. The control group consisted of 49 healthy individuals aged 27 to 72 years (26 females and 23 males) lacking focal and systemic infections with moderately pronounced age-related changes. In plasma samples, concentration of total (non-specific) immunoglobulins of classes E, M, G, A (including secretory immunoglobulin A, sIgA) were measured by using enzyme-linked immunosorbent assay. Data statistical processing was performed by using licensed software packages InStatII, Microsoft Excel, IBM SPSS Statistics 22. An extended range of individual variability in count of peripheral blood CD4 lymphocytes was revealed both among non-survivor and survivor patients with HIV/TB examined, being a drawback of using such parameter as lethality predictor. It was found that the serum level of total IgE, IgM, IgG, IgA and sIgA in patients with HIV/ TB was higher than that one in control group, whereas in non-survivor vs. survivor patients the concentration of IgE and sIgA was elevated. The coefficient of disease outcome prediction (CP) for patients with HIV/TB and MDR MBT was calculated being equal to the ratio of the multiplication of serum concentration of IgE, IgM, IgA and secretory IgA to CD4 lymphocyte count (CP = IgE x IgM x IgA x sIgA/CD4). CP higher than 200 was detected in 77% non-survivor and 6% of survivor patients. The relative risk of death with CP > 200 was very high (OR = 56.7, p < 0.0001) being 8.5 times higher than that one upon CD4 < 200 (OR = 6.7, p = 0.0237). A positive correlation between CP and lethal outcome was more valuable than that of CD4. The data presented allow us to propose CP for clinical use as an effective prognostic criterion for HIV/TB with MDR MBT

Ictal and interictal MEG in pediatric patients with tuberous sclerosis and drug resistant epilepsy

Purpose: Drug resistant epilepsy (DRE) is common in patients with tuberous sclerosis (TS). Interictal MEG has been shown as a valuable instrument in the presurgical workup. The goal of our study was to evaluate the role of ictal MEG in epileptogenic tuber selection, especially in patients with multiple irritative zones. Methods: The clinical and MEG data of 23 patients with TS and DRE from two medical/research centers were reviewed. Seven pediatric patients, who had seizures during MEG recording and underwent resection or disconnection surgery, were included into the study. Cortical sources of ictal and interictal epileptiform MEG discharges were compared with epileptogenic zone location in six patients with favorable surgery outcome. Results: In patients who improved substantially after surgery all resected and several other tubers demonstrated epileptiform activity on interictal MEG. Ictal MEG provided crucial information about lobar location of the seizure onset zone (SOZ) in two cases, and in the other four it confirmed the SOZ location derived from the interictal data. In one case, ictal MEG findings were unreliable. In one patient, who did not benefit from surgical treatment, the resected tubers did not overlap with interictal and ictal MEG sources. Conclusion: The combination of interictal and ictal MEG is a valuable tool for identification of the epileptogenic tuber/tubers in presurgical work-up in patients with TS.Peer reviewe

Laser-induced Demagnetization in van der Waals XYXY- and Ising-like Antiferromagnets NiPS3_3 and FePS3_3

The critical behaviour of laser-induced changes in magnetic ordering is studied experimentally in two-dimensional zigzag antiferromagnets $XY$-like NiPS$_3$ and Ising-like FePS$_3$. To examine laser-induced dynamics in flakes of these compounds, we employ time-resolved exchange linear dichroism effect sensitive to zigzag magnetic ordering and independent of the orientation of the antiferromagnetic vector. In both compounds laser excitation in the vicinity of the absorption edge induces partial quenching of the antiferromagnetic ordering manifested by exchange linear dichroism reduction. The amplitude of the effect varies with temperature as the derivative of the antiferromagnetic vector and exhibits a critical behaviour with the exponents corresponding to $XY$- and Ising-models for NiPS$_3$ and FePS$_3$, respectively. Critical slowing down of the demagnetization in the vicinity of N\'eel temperature is found, however, only in FePS$_3$. In contrast, the increase of the demagnetization time near the ordering temperature in NiPS$_3$ is minor. We show that the difference in the demagnetization times correlates well with the spin specific heat in both compounds. Beyond the range of slowing down, the demagnetization times in NiPS$_3$ and FePS$_3$ are comparable, about 5 - 10 ps, and are longer than those reported earlier for CoPS$_3$ and considerably shorter than for MnPS$_3$. This points to the importance of the unquenched angular momentum of transition-metal ions in laser-induced demagnetization process.Comment: 12 pages, 6 figure

V2324Cyg - an F-type star with fast wind

For the first time high-resolution optical spectroscopy of the variable star V2324Cyg associated with the IR-source IRAS20572+4919 is made. More than 200 absorption features (mostly FeII, TiII, CrII, YII, BaII, and YII) are identified within the wavelength interval 4549-7880AA. The spectral type and rotation velocity of the star are found to be F0III and Vsini=69km/s, respectively. HI and NaID lines have complex PCyg-type profiles with an emission component. Neither systematic trend of radial velocity Vr with line depth Ro nor temporal variability of Vr have been found. We determined the average heliocentric radial velocity Vr=-16.8\pm 0.6km/s. The radial velocities inferred from the cores of the absorption components of the H$\beta$ and NaI wind lines vary from -140 to -225km/s (and the expansion velocities of the corresponding layers, from about 120 to 210km/s). The maximum expansion velocity is found for the blue component of the split H$\alpha$ absorption: 450km/s for December 12, 1995. The model atmospheres method is used to determine the star's parameters: Teff=7500K, log g=2.0, $\xi_t$=6.0km/s, and metallicity, which is equal to the solar value. The main peculiarity of the chemical abundances pattern is the overabundance of lithium and sodium. The results cast some doubt on the classification of V2324Cyg as a post-AGB star.Comment: 28 pages, 6 figure

Electrophysiological, morphological, and ultrastructural features of the injured spinal cord tissue after transplantation of human umbilical cord blood mononuclear cells genetically modified with the VEGF and GDNF genes

© 2017 Y. O. Mukhamedshina et al.In this study, we examined the efficacy of human umbilical cord blood mononuclear cells (hUCB-MCs), genetically modified with the VEGF and GDNF genes using adenoviral vectors, on posttraumatic regeneration after transplantation into the site of spinal cord injury (SCI) in rats. Thirty days after SCI, followed by transplantation of nontransduced hUCB-MCs, we observed an improvement in H (latency period, LP) and M(Amax) waves, compared to the group without therapy after SCI. For genetically modified hUCB-MCs, there was improvement in Amax of M wave and LP of both the M and H waves. The ratio between Amax of the H and M waves (Hmax/Mmax) demonstrated that transplantation into the area of SCI of genetically modified hUCB-MCs was more effective than nontransduced hUCB-MCs. Spared tissue and myelinated fibers were increased at day 30 after SCI and transplantation of hUCB-MCs in the lateral and ventral funiculi 2.5 mm from the lesion epicenter. Transplantation of hUCB-MCs genetically modified with the VEGF and GNDF genes significantly increased the number of spared myelinated fibers (22-fold, P>0.01) in the main corticospinal tract compared to the nontransduced ones. HNA+ cells with the morphology of phagocytes and microglia-like cells were found as compact clusters or cell bridges within the traumatic cavities that were lined by GFAP+ host astrocytes. Our results show that hUCB-MCs transplanted into the site of SCI improved regeneration and that hUCB-MCs genetically modified with the VEGF and GNDF genes were more effective than nontransduced hUCB-MCs