Carbon sequestration in a poplar agroforestry system in India with wheat and other crops at different spacing and row directions

PresentationOwing to its fast growth, deciduous nature, marketing acceptability, and successful intercropping, poplar has become a viable alternative to traditional irrigated rice-wheat rotation in north-western states of India and satisfies the rising requirements of the plywood industry. Agroforestry provides multiple ecological and economical benefits including carbon sequestration, soil and water improvement, raising species diversity and stabilizing farmer’s incomes by diversification. Results show the carbon sequestration potential of poplar based agroforestry systems and effects of spacing as well as row direction. In the study, the wheat crop was sown during the first week of November and harvested in April and no other crop was grown till the next winter wheat crop. For estimation of carbon flows, four carbon pools were considered, viz. above-ground biomass, below-ground biomass, litter and soil carbon. Winter cereals are suited to partner deciduous trees. The crop grows strongly during the initial period from November to mid March, when shading is not a problem. By the time the poplars have developed foliage, the cereal crop is completing its vegetative growth and the ripening of the crop is delayed by two weeks. The yield of the grain and straw decreased sharply from 15 to 65 % under one to six year duration. Organic carbon content in the top soil increased considerably under agroforestry crops with 0.36 % under the six year plantation and 0.22 % under the control. The carbon stock in different carbon pools under study indicated that the above-ground biomass followed by below-ground biomass accumulated to 39 t/ha at the age of 6 years under the agroforestry system compared to 4.9 t/ha of the control. The study strongly reinforces poplar-crops association a better option than the sole agricultural cropping, not for carbon mitigation only but for sustainable productivity as well as profitability

GW190814: gravitational waves from the coalescence of a 23 solar mass black hole with a 2.6 solar mass compact object

We report the observation of a compact binary coalescence involving a 22.2–24.3 Me black hole and a compact object with a mass of 2.50–2.67 Me (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of - + 241 45 41 Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, - + 0.112 0.009 0.008, and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to �0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries

Heat losses from a salt-gradient solar pond

A theoretical approach for the calculation of heat losses from a cylindrical flat-bottomed salt-gradient solar pond is discussed. Steady-state heat losses from the sides and bottom of the pond have been estimated, when the pond is uninsulated as well as insulated. The insulating materials considered in the present study are dry sand, mud powder, dry cement, marble dust and mica powder. The effective insulation is varied by varying the thickness and interstitial air pressure of the insulating materials. We find that the losses are reduced to a minimum with a marble dust wall of thickness 0·20 m at an interstitial air pressure of 0·5 mm of mercury.

All-sky search in early O3 LIGO data for continuous gravitational-wave signals from unknown neutron stars in binary systems

International audienceRapidly spinning neutron stars are promising sources of continuous gravitational waves. Detecting such a signal would allow probing of the physical properties of matter under extreme conditions. A significant fraction of the known pulsar population belongs to binary systems. Searching for unknown neutron stars in binary systems requires specialized algorithms to address unknown orbital frequency modulations. We present a search for continuous gravitational waves emitted by neutron stars in binary systems in early data from the third observing run of the Advanced LIGO and Advanced Virgo detectors using the semicoherent, GPU-accelerated, binaryskyhough pipeline. The search analyzes the most sensitive frequency band of the LIGO detectors, 50–300 Hz. Binary orbital parameters are split into four regions, comprising orbital periods of three to 45 days and projected semimajor axes of two to 40 light seconds. No detections are reported. We estimate the sensitivity of the search using simulated continuous wave signals, achieving the most sensitive results to date across the analyzed parameter space