The idea behind the spillover effect of FDI on economic growth is based on the idea that multinational companies can bring technological innovation and rich knowledge to host countries. Therefore, ...FDI plays a vital role in technological innovations. This study aims to investigate the impact of foreign direct investment (FDI) on the technological innovation of BRICS countries from 2000 to 2020. This study uses the latest econometric techniques, such as the cross-sectional dependence (CD) test, second-generation unit root tests, panel cointegration tests and the Dumitrescu-Hurlin causality test. For long-run run estimation, this study uses the augmented mean group (AMG) panel estimator and the common correlated effects mean group (CCEMG) estimator for empirical analysis. The findings of the study show that foreign direct investment (FDI), trade openness, economic growth, and research & development expenditure positively impact technological innovation in BRICS countries. Also, the model's long-term causality and lagged error correction term (ECT) are significantly negative. Suggested policy measures will be helpful for BRICS economies in boosting technology innovation through FDI.
Polarization measurements of the microquasar Cygnus X-1 exist at γ-ray, X-ray, ultraviolet, optical and radio frequencies. The γ-ray emission has been shown to be highly linearly polarized. Here, we ...present new infrared polarimetric data of Cygnus X-1 taken with the 10.4 m Gran Telescopio Canarias and the 4.2 m William Herschel Telescope. We show that the broad-band, radio-to-γ-ray flux spectrum and polarization spectrum in the hard state are largely consistent with a simple phenomenological model of a strongly polarized synchrotron jet, an unpolarized Comptonized corona and a moderately polarized interstellar dust component. In this model, the origin of the γ-ray, X-ray and some of the infrared polarization is the optically thin synchrotron power law from the inner regions of the jet. The model requires the magnetic field in this region to be highly ordered and perpendicular to the axis of the resolved radio jet. This differs from studies of some other X-ray binaries, in which the magnetic field is turbulent, variable and aligned with the jet axis. The model is able to explain the approximate polarization strength and position angle at all wavelengths including the detected X-ray (3-5 keV) polarization, except the observed position angle of the γ-ray polarization, which differs from the model by ∼60°. Past numerical modelling has shown that a curved synchrotron spectrum can produce a shift in position angle by ∼60°, which may account for this.
High Time-Resolution Astrophysics Shahbaz, Tariq; Casares Velázquez, Jorge; Muñoz Darias, Teodoro
08/2018, Letnik:
v.Series Number 27
eBook
High time-resolution astrophysics (HTRA) involves measuring and studying astronomical phenomena on timescales of seconds to milliseconds. Although many areas of astronomy, such as X-ray astronomy and ...pulsar observations, have traditionally required high time-resolution studies, HTRA techniques are now being applied to optical, infrared and gamma-ray wavelength regimes, due to the development of high efficiency detectors and larger telescopes that can gather photons at a higher rate. With lectures from eminent scientists aimed at young researchers and postdoctorate students in observational astronomy and astrophysics, this volume gives a practical overview and introduction to the tools and techniques of HTRA. Just as multi-spectral observations of astrophysical phenomena are already yielding new scientific results, many astronomers are optimistic that exploring the time domain will open up an important new frontier in observational astronomy over the next decade.
In this paper, we test if any statistically significant periodicities are detectable in carbon monoxide emissions over China, the European Union, and the United States of America. To do this, we ...performed a period analysis using 10 years of daily-averaged data, from the Measurements Of Pollution In The Troposphere (MOPITT) instrument. Besides a seasonal period, we found no clearly detectable periods at any timescale with the exception of a strong signal at 2.28 days. This period was observed over all tested regions and persisted when larger (hemisphere-wide) regions were considered. However, rather than resulting from a physical variation in carbon monoxide, it resulted from day-to-day changes in the area covered by MOPITT on-board its polar-orbiting satellite platform. We also examined linear trends over the dataset, and found that MOPITT identifies several centers of increasing carbon monoxide concentration-the largest being over China-although globally MOPITT reports a significant decrease in carbon monoxide has occurred over the past decade.
We present near-infrared polarimetric observations of the black hole X-ray binaries Swift J1357.2-0933 and A0620-00. In both sources, recent studies have demonstrated the presence of variable ...infrared synchrotron emission in quiescence, most likely from weak compact jets. For Swift J1357.2-0933, we find that the synchrotron emission is polarized at a level of 8.0 plus or minus 2.5 per cent (a 3.2s detection of intrinsic polarization). The mean magnitude and rms variability of the flux (fractional rms of 19-24 per cent in KS band) agree with previous observations. These properties imply a continuously launched (stable on long time-scales), highly variable (on short time-scales) jet in the Swift J1357.2-0933 system in quiescence, which has a moderately tangled magnetic field close to the base of the jet. We find that for A0620-00, there are likely to be three components to the optical-infrared polarization; interstellar dust along the line of sight, scattering within the system, and an additional source that changes the polarization position angle in the reddest (H and KS) wavebands. We interpret this as a stronger contribution of synchrotron emission, and by subtracting the line-of-sight polarization, we measure an excess of ~1.25 plus or minus 0.28 per cent polarization and a position angle of the magnetic field vector that is consistent with being parallel with the axis of the resolved radio jet. These results imply that weak jets in low-luminosity accreting systems have magnetic fields which possess similarly tangled fields compared to the more luminous, hard state jets in X-ray binaries.
The ability of chitinases to degrade the second most abundant polymer, chitin, into potentially useful chitooligomers and chitin derivatives has not only rendered them fit for chitinous waste ...management but has also made them important from industrial point of view. At the same time, they have also been recognized to have an imperative role as promising biocontrol agents for controlling plant diseases. As thermostability is an important property for an industrially important enzyme, various bacterial and fungal sources are being exploited to obtain such stable enzymes. These stable enzymes can also play a role in agriculture by maintaining their stability under adverse environmental conditions for longer time duration when used as biocontrol agent. Biotechnology has also played its role in the development of recombinant chitinases with enhanced activity, thermostability, fungicidal and insecticidal activity via recombinant DNA techniques. Furthermore, a relatively new approach of generating pathogen-resistant transgenic plants has opened new ways for sustainable agriculture by minimizing the yield loss of valuable crops and plants. This review focuses on the potential applications of thermostable and recombinant microbial chitinases in industry and agriculture.
ABSTRACT
AQ Men is a nova-like variable that is presumed to have a tilted, precessing accretion disc. Grazing eclipses in this system have been speculated to be useful in exploring the geometry of ...its accretion disc. In this work, we analysed Transiting Exoplanet Survey Satellite (TESS) observations of AQ Men, which provide the best light curve of this object thus far. We show that the depths of the eclipses are changing with the orientation of the accretion disc, which means that they can serve as a direct test of the tilted accretion disc models. The precession period of the accretion disc is increasing during the TESS observations. However, it is still shorter than the period determined in the previous studies. The amplitude of the variability related to the precession of the accretion disc varies, and so does the shape of this variability. Moreover, we have detected a positive superhump that was previously unseen in AQ Men. Interestingly, the positive superhump has a strongly non-sinusoidal shape, which is not expected for a nova-like variable.
We find a strong correlation between the optical outburst amplitude ΔV and orbital period Porb for the soft X-ray transient sources with orbital periods less than 1 d. By fitting the observed values ...for eight X-ray transients, we determine an empirical relation that can be used to predict the orbital period of an X-ray transient given only its outburst amplitude: ΔV=14.36−7.63 log Porb(h). For periods less than 12 h we determine a relation for the absolute magnitude of the accretion disc during outburst, which then allows us to estimate the distances to the sources.
We present the discovery of a variable optical counterpart to the unidentified gamma-ray source 3FGL J0212.1+5320 and argue that this is a new compact binary millisecond pulsar (MSP) candidate. We ...show 3FGL J0212.1+5320 hosts a semidetached binary with a 0.869 55 plus or minus 0.000 15 d orbital period and an F6-type companion star at an estimated distance of D = 1.1 plus or minus 0.2 kpc, with a radial velocity curve semi-amplitude K sub( 2) = 214.1 plus or minus 5.0 km s super( -1) and a projected rotational velocity of V sin (i) = 73.2 plus or minus 1.6 km s super( -1). We find a hard X-ray source at the same location with a 0.5-10 keV luminosity L sub( X) = 2.6 x 10 super( 32) (D/1.1 kpc) super( 2) erg s super( -1), which strengthens the MSP identification. Our results imply a mass ratio q = M sub( 2)/M sub( 1) = 0.26... if the companion star fills its Roche lobe, and q ... 0.26 in any case. This classifies 3FGL J0212.1+5320 as a 'redback' binary MSP; if its MSP nature is confirmed, this will be the brightest compact binary MSP in the optical band (r" NOT approximately equal to 14.3 mag) and will have the longest orbital period among Galactic field systems (nearly 21 h). Based on the light curve peak-to-peak amplitude ( Delta r = 0.19 mag), we further suggest that the orbital inclination is high and the putative pulsar mass is close to canonical (M sub( 1) NOT approximately equal to 1.3-1.6 M...). Finally, we discuss the lack of heating signatures and asymmetric optical light curves in the context of other redback MSPs. (ProQuest: ... denotes formulae/symbols omitted.)
ABSTRACT
We present ULTRACAM multiband optical photometry of two transitional millisecond pulsars (tMSPs), PSR J1023+0038 and PSR J1227−4853, taken while both were in their radio pulsar states. The ...light curves show significant asymmetry about the flux maxima in all observed bands, suggesting an asymmetric source of heating in the system. We model the light curves using the icarus binary code, using models with an additional ‘hotspot’ heating contribution and an anisotropic heat redistribution model to treat the asymmetry. Our modelling reveals companion stars with underfilled Roche lobes in both PSRs J1023+0038 and J1227−4853, with Roche lobe filling factors in the range f ∼ 0.82−0.92. While the volume-averaged filling factors are closer to unity, significant underfilling is unexpected from tMSPs as they must rapidly overfill their Roche lobes to start transferring mass, which occurs on time-scale of weeks or months. We discuss the motivation and validity of our extensions to the models and the implications of the underfilled Roche lobe, and suggest future work to further investigate the role of the filling factor in the tMSP cycle.
PDF
