Determinants of Child Labour in Indian States: Some Empirical Explorations (1961-1991)

child labour ; India

The Interface between economic development, health and environment in India: An econometric investigation.

This paper analyses interrelationships between `economic development', `health', and `environment' in a simultaneous equations framework. Four structural equations have been postulated to explain changes in four endogenous variables in terms of several predetermined variables. The endogenous variables chosen for the model are GDPPC (per capita gross domestic product), LE (life expectancy), NOCRD (number of cases of respiratory diseases) and PM10 (respirable suspended particulate matter). We assume that GDPPC describes economic development prominently and, therefore, use it as one of the endogenous variables in lieu of economic development. LE and NOCRD are assumed to reflect health effects in the economy, and PM10 is used as a proxy of environmental stress. The four endogenous variables are supposed to be jointly determined in terms of several exogenous variables represented through indices of physical infrastructure (PI), social infrastructure (SI) and air pollution index (API). We construct the three indices by the principal components method and thus effectively use only these three predetermined (exogenous) variables to simultaneously determine changes in the four endogenous variables listed above. The model is postulated in loglinear form and estimated by the two-stage least-squares method using data from the Indian economy 1980-81 to 2004-05. It follows from the estimated structural equations that while physical infrastructure is significant in determining GDPPC, the GDPPC is also directly influenced by improved health outcomes like longevity (LE) and lower morbidity from respiratory diseases (NOCRD). The long term health outcome (LE) is determined by the level of per capita GDP and it is positively affected by social infrastructure. The third structural equation shows that the immediate, or short run, health outcomes like morbidity from respiratory disorders are influenced by environmental stress (PM10) besides the level of GDPPC. Finally, the environmental stress (PM10) is determined by the level of per capita GDP and the air pollution index (API) representing various sources of air pollution. It is true that our simplified model illustrates the effects of specific type of air pollutant, viz., respirable particulate matter, however, it is among the most significant environmental problems threatening human health in India. Nevertheless, there is scope to build more comprehensive environmental stress indices which reflect surface water quality, ground water quality, soil pollution etc. which have feedback effects with health and economic development. Also many of the components of PI, SI and API may not be truly exogenous in a larger model (e.g. transport and communication in PI, education and health care systems in SI, and industrial production, vehicular traffic, urbanisation in API.) The two weaknesses of our model stem from data limitation and a concern to simplify the model. Although our model is highly simplified, nonetheless, it provides key insights into the nature of economic development in India during the last 25 years: First, the environmental stress has had a high cost on income and health . from the derived reduced form, a 1 percent increase in the air pollution index leads to a decrease of about 8 percent in the per capita income, a decrease of about 0.7 percent in the life expectancy, and an increase of about 19 percent in the number of cases of respiratory diseases. Second, the social infrastructure plays a more vital role in economic development, health, and environment than the physical infrastructure, since the absolute values of elasticities of endogenous variables with respect to SI are invariably greater than those with respect to PI. Although physical infrastructure is important for economic development, it comes in the last of our preference order. In the final run-up, there is need to pay more attention to provide better social infrastructure and to reduce air pollution.

Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model

We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47×10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society

Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)

[no abstract available

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society

The polarized image of a synchrotron-emitting ring of gas orbiting a black hole

High Energy Astrophysic

Constraints on black-hole charges with the 2017 EHT observations of M87*

InstrumentationHigh Energy Astrophysic

The variability of the black hole image in M87 at the dynamical timescale

The black hole images obtained with the Event Horizon Telescope (EHT) are expected to be variable at the dynamical timescale near their horizons. For the black hole at the center of the M87 galaxy, this timescale (5–61 days) is comparable to the 6 day extent of the 2017 EHT observations. Closure phases along baseline triangles are robust interferometric observables that are sensitive to the expected structural changes of the images but are free of station-based atmospheric and instrumental errors. We explored the day-to-day variability in closure-phase measurements on all six linearly independent nontrivial baseline triangles that can be formed from the 2017 observations. We showed that three triangles exhibit very low day-to-day variability, with a dispersion of ∼3°–5°. The only triangles that exhibit substantially higher variability (∼90°–180°) are the ones with baselines that cross the visibility amplitude minima on the u–v plane, as expected from theoretical modeling. We used two sets of general relativistic magnetohydrodynamic simulations to explore the dependence of the predicted variability on various black hole and accretion-flow parameters. We found that changing the magnetic field configuration, electron temperature model, or black hole spin has a marginal effect on the model consistency with the observed level of variability. On the other hand, the most discriminating image characteristic of models is the fractional width of the bright ring of emission. Models that best reproduce the observed small level of variability are characterized by thin ring-like images with structures dominated by gravitational lensing effects and thus least affected by turbulence in the accreting plasmas.https://iopscience.iop.org/article/10.3847/1538-4357/ac332e/pdfPublished versio