Context. Gaia18cjb is one of the Gaia-alerted eruptive young star candidates which has been experiencing a slow and strong brightening during the last 13 years, similar to some FU Orionis-type ...objects. Aims. The aim of this work is to derive the young stellar nature of Gaia18cjb, determine its physical and accretion properties to classify its variability. Methods. We conducted monitoring observations using multi-filter optical and near-infrared photometry, as well as near-infrared spectroscopy. We present the analysis of pre-outburst and outburst optical and infrared light curves, color-magnitude diagrams in different bands, the detection of near-IR spectral lines, and estimates of both stellar and accretion parameters during the burst. Results. The optical light curve shows an unusually long (8 years) brightening event of 5 mag in the last 13 years, before reaching a plateau indicating that the burst is still on-going, suggesting a FUor-like nature. The same outburst is less strong in the infrared light curves. The near-infrared spectra, obtained during the outburst, exhibit emission lines typical of highly accreting low-intermediate mass young stars with typical EXor features. The spectral index of Gaia18cjb SED classifies it as a Class I in the pre-burst stage and a Flat Spectrum young stellar object (YSO) during the burst. Conclusions. Gaia18cjb is an eruptive YSO which shows FUor-like photometric features (in terms of brightening amplitude and length of the burst) and EXor-like spectroscopic features and accretion rate, as V350 Cep and V1647 Ori, classified as objects in between FUors and EXors
Accretion plays a central role in the physics that governs the evolution and
dispersal of protoplanetary disks. The primary goal of this paper is to analyze
the stability over time of the mass ...accretion rate onto TW Hya, the nearest
accreting solar-mass young star. We measure veiling across the optical spectrum
in 1169 archival high-resolution spectra of TW Hya, obtained from 1998--2022.
The veiling is then converted to accretion rate using 26 flux-calibrated
spectra that cover the Balmer jump. The accretion rate measured from the excess
continuum has an average of $2.51\times10^{-9}$~M$_\odot$~yr$^{-1}$ and a
Gaussian distribution with a FWHM of 0.22 dex. This accretion rate may be
underestimated by a factor of up to 1.5 because of uncertainty in the
bolometric correction and another factor of 1.7 because of excluding the
fraction of accretion energy that escapes in lines, especially Ly$\alpha$. The
accretion luminosities are well correlated with He line luminosities but poorly
correlated with H$\alpha$ and H$\beta$ luminosity. The accretion rate is always
flickering over hours but on longer timescales has been stable over 25 years.
This level of variability is consistent with previous measurements for most,
but not all, accreting young stars.
Tuberculosis pertains to every third HIV-positive person in a world. Therefore HIV infection is considered the most evident risk factor for the primary tuberculosis or relapse of latent tubercular ...infection. Pulmonary tuberculosis is the most frequent clinical presentation in HIV-positive individuals, although the frequency of extrapulmonary tuberculosis is increasing with the CD4+ count reduction. Tuberculin skin testing and bacteriological tests are regarded as a "gold standard" of diagnosis. Molecular diagnostics and evaluation of a whole-blood interferon-gamma release assay for the detection of Mycobacterium tuberculosis are not cost-effective therefore their application is limited. DOTS programs are recommended for the antimycobacterial treatment in HIV-infected patients. The increasing drug resistance of Mycobacterium tuberculosis (multi-drug resistant tuberculosis--MDRTB) is emerging problem in the field of tuberculosis management.
We experimentally demonstrate the operation of a Josephson magnetic random access memory unit cell, built with a Ni_80Fe_20/Cu/Ni pseudo spin-valve Josephson junction with Nb electrodes and an ...integrated readout SQUID in a fully planarized Nb fabrication process. We show that the parallel and anti-parallel memory states of the spin-valve can be mapped onto a junction equilibrium phase of either zero or pi by appropriate choice of the ferromagnet thicknesses, and that the magnetic Josephson junction can be written to either a zero-junction or pi-junction state by application of write fields of approximately 5 mT. This work represents a first step towards a scalable, dense, and power-efficient cryogenic memory for superconducting high-performance digital computing.
Context. We investigate small-amplitude light variations in FU Ori occurring in timescales of days and weeks. Aims. We seek to determine the mechanisms that lead to these light changes. Methods. The ...visual light curve of FU Ori gathered by the MOST satellite continuously for 55 days in the 2013-2014 winter season and simultaneously obtained ground-based multi-colour data were compared with the results from a disc and star light synthesis model. Results. Hotspots on the star are not responsible for the majority of observed light variations. Instead, we found that the long periodic family of 10.5-11.4 d (presumably) quasi-periods showing light variations up to 0.07 mag may arise owing to the rotational revolution of disc inhomogeneities located between 16-20 solar radii. The same distance is obtained by assuming that these light variations arise because of a purely Keplerian revolution of these inhomogeneities for a stellar mass of 0.7 solar mass. The short-periodic (3-1.38 d) small amplitude (0.01 mag) light variations show a clear sign of period shortening, similar to what was discovered in the first MOST observations of FU Ori. Our data indicate that these short-periodic oscillations may arise because of changing visibility of plasma tongues (not included in our model), revolving in the magnetospheric gap and/or likely related hotspots as well. Conclusions. Results obtained for the long-periodic 10-11 d family of light variations appear to be roughly in line with the colour-period relation, which assumes that longer periods are produced by more external and cooler parts of the disc. Coordinated observations in a broad spectral range are still necessary to fully understand the nature of the short-periodic 1-3 d family of light variations and their period changes.
Quantitative micrococulture assays of cryopreserved human immunodeficiency virus type 1-infected cell suspensions and culture supernatants were compared among seven assay sites. There was no ...significant change in titer during 1 year of storage. The overall standard deviation for infected cell suspensions was approximately 0.8 log sub(10) virus titer. A method for detecting deviant assay results was developed and was used to identify two donor cell preparations (n = 54) that gave consistently low titers.
Results of the time variability monitoring of the two classical T Tauri stars, RU Lup and IM Lup, are presented. Three photometric data sets were utilised: (1) simultaneous (same field) MOST ...satellite observations over four weeks in each of the years 2012 and 2013, (2) multicolour observations at the SAAO in April - May of 2013, (3) archival V-filter ASAS data for nine seasons, 2001 - 2009. They were augmented by an analysis of high-resolution, public-domain VLT-UT2 UVES spectra from the years 2000 to 2012. From the MOST observations, we infer that irregular light variations of RU Lup are caused by stochastic variability of hot spots induced by unstable accretion. In contrast, the MOST light curves of IM Lup are fairly regular and modulated with a period of about 7.19 - 7.58 d, which is in accord with ASAS observations showing a well defined 7.247+/-0.026 d periodicity. We propose that this is the rotational period of IM Lup and is due to the changing visibility of two antipodal hot spots created near the stellar magnetic poles during the stable process of accretion. Re-analysis of RU Lup high-resolution spectra with the Broadening Function approach reveals signs of a large polar cold spot, which is fairly stable over 13 years. As the star rotates, the spot-induced depression of intensity in the Broadening Function profiles changes cyclically with period 3.71058 d, which was previously found by the spectral cross-correlation method.
We present an analysis of the 2011 photometric observations of TW Hya by the MOST satellite; this is the fourth continuous series of this type. The large-scale light variations are dominated by a ...strong, quasi-periodic 4.18 d oscillation with superimposed, apparently chaotic flaring activity; the former is most likely produced by stellar rotation with one large hot spot created by a stable accretion funnel in the stable regime of accretion while the latter may be produced by small hot spots, created at moderate latitudes by unstable accretion tongues. A new, previously unnoticed feature is a series of semi-periodic, well defined brightness dips of unknown nature of which 19 were observed during 43 days of our nearly-continuous observations. Re-analysis of the 2009 MOST light curve revealed the presence of 3 similar dips. On the basis of recent theoretical results, we tentatively conclude that the dips may represent occultations of the small hot spots created by unstable accretion tongues by hypothetical optically thick clumps.
Cerebrospinal fluid (CSF) serotonin was determined in 38 patients with pyogenic meningitis and tick-borne encephalitis (TBE) before and after treatment. Increase of CSF serotonin concentration was ...observed in acute phase of pyogenic meningits and normalized after treatment.
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