We present optical, UV, and X-ray monitoring of the short orbital period black hole X-ray binary candidate Swift J1753.5-0127, focusing on the final stages of its 12 yr long outburst that started in ...2005. From 2016 September onward, the source started to fade, and within 3 months, the optical flux almost reached the quiescent level. Soon after that, using a new proposed rebrightening classification method, we recorded a mini-outburst and a reflare in the optical light curves, peaking in 2017 February (V ∼ 17.0) and May (V ∼ 17.9), respectively. Remarkably, the mini-outburst has a peak flux consistent with the extrapolation of the slow decay before the fading phase preceding it. The following reflare was fainter and shorter. We found from optical colors that the temperature of the outer disk was ∼11,000 K when the source started to fade rapidly. According to the disk instability model, this is close to the critical temperature when a cooling wave is expected to form in the disk, shutting down the outburst. The optical color could be a useful tool to predict decay rates in some X-ray transients. We notice that all X-ray binaries that show mini-outbursts following a main outburst are short orbital period systems (<7 hr). In analogy with another class of short-period binaries showing similar mini-outbursts, the cataclysmic variables of the RZ LMi type, we suggest that mini-outbursts could occur if there is a hot inner disk at the end of the outburst decay.
Some properties of three-qubit systems interacting with a noisy environment are discussed. The amount of the survival entanglement is quantified for the Greenberger–Horne–Zeilinger (GHZ) and W ...states. It is shown that the entanglement decay depends on the noise type (correlated or non-correlated), the number of interacting qubits with the environment, and the initial state that passes through this noisy environment. In general, the GHZ state is more fragile than the W state. The phenomenon of entanglement sudden death appears in the GHZ state only for non-correlated noise.
Gaia16aye was a binary microlensing event discovered in the direction towards the northern Galactic disc and was one of the first microlensing events detected and alerted to by the
Gaia
space ...mission. Its light curve exhibited five distinct brightening episodes, reaching up to
I
= 12 mag, and it was covered in great detail with almost 25 000 data points gathered by a network of telescopes. We present the photometric and spectroscopic follow-up covering 500 days of the event evolution. We employed a full Keplerian binary orbit microlensing model combined with the motion of Earth and
Gaia
around the Sun to reproduce the complex light curve. The photometric data allowed us to solve the microlensing event entirely and to derive the complete and unique set of orbital parameters of the binary lensing system. We also report on the detection of the first-ever microlensing space-parallax between the Earth and
Gaia
located at L2. The properties of the binary system were derived from microlensing parameters, and we found that the system is composed of two main-sequence stars with masses 0.57 ± 0.05
M
⊙
and 0.36 ± 0.03
M
⊙
at 780 pc, with an orbital period of 2.88 years and an eccentricity of 0.30. We also predict the astrometric microlensing signal for this binary lens as it will be seen by
Gaia
as well as the radial velocity curve for the binary system. Events such as Gaia16aye indicate the potential for the microlensing method of probing the mass function of dark objects, including black holes, in directions other than that of the Galactic bulge. This case also emphasises the importance of long-term time-domain coordinated observations that can be made with a network of heterogeneous telescopes.
Asthma causes a high economic burden on the health-care system. Previous research on the cost of asthma in Abu Dhabi was in 2011 and revealed high medical costs. This work aimed to estimate both ...direct and indirect costs of asthma with trend analysis over a period of four years.
All data on medical costs, work absenteeism, and mortality were collected from the e-claims system of the national health insurance database. Medical costs included medication use, emergency room (ER) visits, non-ER visits, outpatient care, and hospitalization from 2015 to 2018. Indirect costs in terms of work absenteeism were calculated by multiplying the average daily income per employer by the number of workdays missed due to sick leaves documented in the database in 2019.
Over the years, the total medical costs increased from AED 161,843,698 in 2015 to AED 206,548,620 in 2018. The largest contribution was attributed to outpatient care, while hospitalization accounted for the smallest proportion of the total costs in 2018. Likewise, the mean annual per-patient cost in 2015 was AED 1119 and increased to AED 1162 in 2018. Indirect costs were estimated to be AED 27,482,319 resulting from 30,948 sick leaves in the year 2019 only.
Asthma is a cause for huge expenditure from the health-care system perspective in Abu Dhabi. It also has a large impact on society through work absenteeism. Costs of asthma management are increasing every year, which suggests a call-to-action to improve the disease management status using cost-effective strategies.
The Greater Cairo metro-Line 3, the major project of underground structure in Cairo city, Egypt, is currently under constructed. Ground movement is expected during the construction with tunneling ...boring machine as Cairo metro tunnel passes through sand soil.
In the present study, finite element model is used to model tunnel system performance based on the case study. An elasto-plastic constitutive model is adopted to represent the soil behavior surrounding the tunnel. The effects are expressed in terms of surface displacement and soil stress change caused by tunneling. The subsoil stresses undergo three phases of change. At these phases, the loading steps of the tunnel construction are predicted using the 2-D finite element analysis.
Ground movement and construction influence are obtained by the numerical model. A comparison is made between the computed tunnel performance and the observed behavior. The comparison reveals a good agreement between the calculated and the observed values.
Some properties of multi-qubit systems interacting with noisy environment is discussed. The amount of the survival entanglement is quantified for the GHZ and W-states. It is shown that the ...entanglement decay depends on the noise type ( correlated or non-correlated), number of interacted qubits with the environment and the initial state which passes through this noisy environment. In general, the GHZ is more fragile than the W-state. The phenomena of entanglement sudden death appears only for non-correlated noise.
We describe the performance of a $\mathrm{23\times 23\times30 ~mm^3}$ low
background cerium bromide, CeBr$_3$(LB), scintillator crystal coupled to a
Hamamatsu R11265U-200 photomultiplier. This ...detector will be the building block
for a gamma-ray detector array designed to be the payload for a CubeSat to be
launched in 2020. The aim of the mission is to study flashes of gamma rays of
terrestrial origin. The design of the detector has been tuned for the detection
of gamma rays in the 20 keV$-$3 MeV energy range.
Disc instability models predict that for X-ray binaries in quiescence, there should be a brightening of the optical flux prior to an X-ray outburst. Tracking the X-ray variations of X-ray binaries in ...quiescence is generally not possible, so optical monitoring provides the best means to measure the mass accretion rate variability between outbursts, and to identify the beginning stages of new outbursts. With our regular Faulkes Telescope/Las Cumbres Observatory (LCO) monitoring we are routinely detecting the optical rise of new X-ray binary outbursts before they are detected by X-ray all-sky monitors. We present examples of detections of an optical rise in X-ray binaries prior to X-ray detection. We also present initial optical monitoring of the new black hole transient MAXI J1820+070 (ASASSN-18ey) with the Faulkes, LCO telescopes and Al Sadeem Observatory in Abu Dhabi, UAE. Finally, we introduce our new real-time data analysis pipeline, the 'X-ray Binary New Early Warning System (XB-NEWS)' which aims to detect and announce new X-ray binary outbursts within a day of first optical detection. This will allow us to trigger X-ray and multi-wavelength campaigns during the very early stages of outbursts, to constrain the outburst triggering mechanism.
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