Is the Post-AGB Star SAO 40039 Mildly Hydrogen-Deficient?

We have conducted an LTE abundance analysis for SAO 40039, a warm post-AGB star whose spectrum is known to show surprisingly strong He I lines for its effective temperature and has been suspected of being H-deficient and He-rich. High-resolution optical spectra are analyzed using a family of model atmospheres with different He/H ratios. Atmospheric parameters are estimated from the ionization equilibrium set by neutral and singly ionized species of Fe and Mg, the excitation of Fe I and Fe II lines, and the wings of the Paschen lines. On the assumption that the He I lines are of photospheric and not chromospheric origin, a He/H ratio of approximately unity is found by imposing the condition that the adopted He/H ratio of the model atmosphere must equal the ratio derived from the observed He I triplet lines at 5876, 4471, and 4713 angstrom, and singlet lines at 4922 and 5015 angstrom. Using the model with the best-fitting atmospheric parameters for this He/H ratio, SAO 40039 is confirmed to exhibit mild dust-gas depletion, I. e., the star has an atmosphere deficient in elements of high condensation temperature. The star appears to be moderately metal-deficient with [Fe/H] = -0.4 dex. But the star's intrinsic metallicity as estimated from Na, S, and Zn, elements of a low condensation temperature, is [Fe/H](o) similar or equal to -0.2 ([Fe/H](o) refers to the star's intrinsic metallicity). The star is enriched in N and perhaps O as well, changes reflecting the star's AGB past and the event that led to He enrichment.National Science FoundationRobert A. Welch Foundation of Houston, Texas F-634McDonald Observator

ROLE OF INDIAN TRADITIONAL MEDICINE IN MITIGATING NOVEL CORONA VIRUS EFFECTS.

Novel Coronavirus (2019-nCoV) with a distinct feature of transmitting debilitating infection from person to person, originated in Wuhan, China, was identified during  December 2019,  has affected many persons in China and spread to other countries in a very short period of time. When the whole world is trying to combat COVID-19, the respiratory disease caused by  novel Corona virus, there is urgent need to explore the efficacy of  alternate medicine as preventive measure.  Traditional medicine which boost the immune system may be one of the best and immediate answer to this global health crisis. Although the WHO said: “To date, there is no specific medicine recommended to prevent or treat the novel Coronavirus, several studies explored inhibition of viral replication through medicinal plant extracts.  Myriad herbal remedies, some scientifically supported, are used to treat cold and flu symptoms. Herbs such as tulsi, giloy,  lemon balm, mint and also amla, methi, ginger, turmeric are helpful in strengthening the immune system which is key to fighting the deadly virus. Several  oils and selected  fruits  also increase efficiency of immune system thus protecting the body against viral infections especially against respiratory illnesses.

IRAS\,11472-0800: an extremely depleted pulsating binary post-AGB star

We focus here on one particular and poorly studied object, IRAS11472-0800. It is a highly evolved post-Asymptotic Giant Branch (post-AGB) star of spectral type F, with a large infrared excess produced by thermal emission of circumstellar dust. We deploy a multi-wavelength study which includes the analyses of optical and IR spectra as well as a variability study based on photometric and spectroscopic time-series. The spectral energy distribution (SED) properties as well as the highly processed silicate N-band emission show that the dust in IRAS11472-0800 is likely trapped in a stable disc. The energetics of the SED and the colour variability show that our viewing angle is close to edge-on and that the optical flux is dominated by scattered light. With photospheric abundances of [Fe/H] = -2.7 and [Sc/H]=-4.2, we discovered that IRAS11472-0800 is one of the most chemically-depleted objects known to date. Moreover, IRAS11472-0800 is a pulsating star with a period of 31.16 days and a peak-to-peak amplitude of 0.6 mag in V. The radial velocity variability is strongly influenced by the pulsations, but the significant cycle-to-cycle variability is systematic on a longer time scale, which we interpret as evidence for binary motion. We conclude that IRAS11472-0800 is a pulsating binary star surrounded by a circumbinary disc. The line-of-sight towards the object lies close the the orbital plane making that the optical light is dominated by scattered light. IRAS11472-0800 is one of the most chemically-depleted objects known so far and links the dusty RV\,Tauri stars to the non-pulsating class of strongly depleted objects.Comment: 12 pages, 14 figures Accepted for publication in A&A Main Journa

Time resolved spectroscopy of BD+46 442: gas streams and jet creation in a newly discovered evolved binary with a disk

Previous studies have shown that many post-AGB stars with dusty disks are associated with single-lined binary stars. To verify the binarity hypothesis on a larger sample, we started a high-resolution spectral monitoring of about 40 field giants, whose binarity was suspected based on either a light curve, an infrared excess, or a peculiar chemical composition. Here we report on the discovery of the periodic RV variations in BD+46 442, a high-latitude F giant with a disk. We interpret the variations due to the motion around a faint companion, and deduce the following orbital parameters: Porb = 140.77 d, e = 0.083, asini=0.31 AU. We find it to be a moderately metal-poor star ([M/H]=-0.7) without a strong depletion pattern in the photospheric abundances. Interestingly, many lines show periodic changes with the orbital phase: Halpha switches between a double-peak emission and a PCyg-like profiles, while strong metal lines appear split during the maximum redshift. Similar effects are likely visible in the spectra of other post-AGB binaries, but their regularity is not always realized due to sporadic observations. We propose that these features result from an ongoing mass transfer from the evolved giant to the companion. In particular, the blue-shifted absorption in Halpha, which occurs only at superior conjunction, may result from a jet originating in the accretion disk around the companion and seen in absorption towards the luminous primary.Comment: 16 pages, accepted in A&

Antenatal dexamethasone for early preterm birth in low-resource countries

BACKGROUND: The safety and efficacy of antenatal glucocorticoids in women in low-resource countries who are at risk for preterm birth are uncertain. METHODS: We conducted a multicountry, randomized trial involving pregnant women between 26 weeks 0 days and 33 weeks 6 days of gestation who were at risk for preterm birth. The participants were assigned to intramuscular dexamethasone or identical placebo. The primary outcomes were neonatal death alone, stillbirth or neonatal death, and possible maternal bacterial infection; neonatal death alone and stillbirth or neonatal death were evaluated with superiority analyses, and possible maternal bacterial infection was evaluated with a noninferiority analysis with the use of a prespecified margin of 1.25 on the relative scale. RESULTS: A total of 2852 women (and their 3070 fetuses) from 29 secondary- and tertiary-level hospitals across Bangladesh, India, Kenya, Nigeria, and Pakistan underwent randomization. The trial was stopped for benefit at the second interim analysis. Neonatal death occurred in 278 of 1417 infants (19.6%) in the dexamethasone group and in 331 of 1406 infants (23.5%) in the placebo group (relative risk, 0.84; 95% confidence interval [CI], 0.72 to 0.97; P=0.03). Stillbirth or neonatal death occurred in 393 of 1532 fetuses and infants (25.7%) and in 444 of 1519 fetuses and infants (29.2%), respectively (relative risk, 0.88; 95% CI, 0.78 to 0.99; P=0.04); the incidence of possible maternal bacterial infection was 4.8% and 6.3%, respectively (relative risk, 0.76; 95% CI, 0.56 to 1.03). There was no significant between-group difference in the incidence of adverse events. CONCLUSIONS: Among women in low-resource countries who were at risk for early preterm birth, the use of dexamethasone resulted in significantly lower risks of neonatal death alone and stillbirth or neonatal death than the use of placebo, without an increase in the incidence of possible maternal bacterial infection.Fil: Oladapo, Olufemi T.. Organizacion Mundial de la Salud; ArgentinaFil: Vogel, Joshua P.. Organizacion Mundial de la Salud; ArgentinaFil: Piaggio, Gilda. Organizacion Mundial de la Salud; ArgentinaFil: Nguyen, My-Huong. Organizacion Mundial de la Salud; ArgentinaFil: Althabe, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; ArgentinaFil: Metin Gülmezoglu, A.. Organizacion Mundial de la Salud; ArgentinaFil: Bahl, Rajiv. Organizacion Mundial de la Salud; ArgentinaFil: Rao, Suman P.N.. Organizacion Mundial de la Salud; ArgentinaFil: de Costa, Ayesha. Organizacion Mundial de la Salud; ArgentinaFil: Gupta, Shuchita. Organizacion Mundial de la Salud; ArgentinaFil: Shahidullah, Mohammod. No especifíca;Fil: Chowdhury, Saleha B.. No especifíca;Fil: Ara, Gulshan. No especifíca;Fil: Akter, Shaheen. No especifíca;Fil: Akhter, Nasreen. No especifíca;Fil: Dey, Probhat R.. No especifíca;Fil: Abdus Sabur, M.. No especifíca;Fil: Azad, Mohammad T.. No especifíca;Fil: Choudhury, Shahana F.. No especifíca;Fil: Matin, M.A.. No especifíca;Fil: Goudar, Shivaprasad S.. No especifíca;Fil: Dhaded, Sangappa M.. No especifíca;Fil: Metgud, Mrityunjay C.. No especifíca;Fil: Pujar, Yeshita V.. No especifíca;Fil: Somannavar, Manjunath S.. No especifíca;Fil: Vernekar, Sunil S.. No especifíca;Fil: Herekar, Veena R.. No especifíca;Fil: Bidri, Shailaja R.. No especifíca;Fil: Mathapati, Sangamesh S.. No especifíca;Fil: Patil, Preeti G.. No especifíca;Fil: Patil, Mallanagouda M.. No especifíca;Fil: Gudadinni, Muttappa R.. No especifíca;Fil: Bijapure, Hidaytullah R.. No especifíca;Fil: Mallapur, Ashalata A.. No especifíca;Fil: Katageri, Geetanjali M.. No especifíca;Fil: Chikkamath, Sumangala B.. No especifíca;Fil: Yelamali, Bhuvaneshwari C.. No especifíca;Fil: Pol, Ramesh R.. No especifíca;Fil: Misra, Sujata S.. No especifíca;Fil: Das, Leena. No especifíca

Identification of slot discharges in rotating machine insulation system using variable frequency PD measurement

Slot discharge studies are very important from the insulation diagnosis perspective. Further in practice, testing of rotating machines with power frequency requires sources which are quite bulky and costly. Instead if the diagnosis is carried out at lower frequencies (<50 Hz), the size and cost of the test source can be reduced significantly. Therefore, it is important to know whether the study at low frequencies can be considered equivalent to study at power frequency. Hence, in this study, a slot discharge phenomenon occurring in a rotating machine insulation system was investigated experimentally at different frequencies (50, 10, 1 and 0.1 Hz). Slot discharges are known to have a distinct phase resolved partial discharge pattern for power frequency (50/60 Hz) excitation. These distinct patterns are useful in identifying the presence of slot discharge activity in rotating machines. Slot discharges were created on a 6.6 kV mica-epoxy stator coil and the slot discharge characteristics measured at different frequencies are compared. Slot discharge measurements were repeated by varying the air gap between the insulation surface and grounded steel plate. The changes in slot discharge characteristics due to the increase in air gap were found similar at all frequencies. The comparison suggests that the identification of slot discharge is also possible from the partial discharge (PD) measurement at low frequencies