Pedaling out of poverty: Social impact of a manual irrigation technology in South Asia.

Irrigation management / Treadle pump / Treadle pump technology / Technology transfer / Manual pumps / Water lifting / Low lift pumps / Aquifers / Poverty / Irrigated farming / Social impact / Income / Marketing / Pricing / South Asia / India / Bangladesh / Nepal

Binary black hole merger in the extreme-mass-ratio limit: a multipolar analysis

Building up on previous work, we present a new calculation of the gravitational wave (GW) emission generated during the transition from quasi-circular inspiral to plunge, merger and ringdown by a binary system of nonspinning black holes, of masses $m_1$ and $m_2$, in the extreme mass ratio limit, $m_1 m_2\ll(m_1+m_2)^2$. The relative dynamics of the system is computed {\it without making any adiabatic approximation} by using an effective one body (EOB) description, namely by representing the binary by an effective particle of mass $\mu=m_1 m_2/(m_1+m_2)$ moving in a (quasi-)Schwarzschild background of mass $M=m_1+m_2$ and submitted to an \O(\nu) 5PN-resummed analytical radiation reaction force, with $\nu=\mu/M$. The gravitational wave emission is calculated via a multipolar Regge-Wheeler-Zerilli type perturbative approach (valid in the limit $\nu\ll 1$). We consider three mass ratios, $\nu={10^{-2},10^{-3},10^{-4}}$,and we compute the multipolar waveform up to $\ell=8$. We estimate energy and angular momentum losses during the quasi-universal and quasi-geodesic part of the plunge phase and we analyze the structure of the ringdown. We calculate the gravitational recoil, or "kick", imparted to the merger remnant by the gravitational wave emission and we emphasize the importance of higher multipoles to get a final value of the recoil $v/(c\nu^2)=0.0446$. We finally show that there is an {\it excellent fractional agreement} ($\sim 10^{-3}$) (even during the plunge) between the 5PN EOB analytically-resummed radiation reaction flux and the numerically computed gravitational wave angular momentum flux. This is a further confirmation of the aptitude of the EOB formalism to accurately model extreme-mass-ratio inspirals, as needed for the future space-based LISA gravitational wave detector.Comment: 20 pages, 12 figures. Version published in Phys. Rev.

Gas inflows towards the nucleus of the active galaxy NGC7213

We present two-dimensional stellar and gaseous kinematics of the inner 0.8x1.1kpc^2 of the LINER/Seyfert 1 galaxy NGC7213, from optical spectra obtained with the GMOS integral field spectrograph on the Gemini South telescope at a spatial resolution of 60pc. The stellar kinematics shows an average velocity dispersion of 177km/s, circular rotation with a projected velocity amplitude of 50km/s and a kinematic major axis at a position angle of -4degrees (west of north). From the average velocity dispersion we estimate a black hole mass of M_BH=8_{-6}^{+16}x10^7 M_sun. The gas kinematics is dominated by non-circular motions, mainly along two spiral arms extending from the nucleus out to 4arcsec (280pc) to the NW and SE, that are cospatial with a nuclear dusty spiral seen in a structure map of the nuclear region of the galaxy. The projected gas velocities along the spiral arms show blueshifts in the far side and redshifts in the near side, with values of up to 200km/s. This kinematics can be interpreted as gas inflows towards the nucleus along the spiral arms if the gas is in the plane of the galaxy. We estimate the mass inflow rate using two different methods. The first is based of the observed velocities and geometry of the flow, and gives a mass inflow rate in the ionised gas of 7x10^-2 M_sun/yr. In the second method, we calculate the net ionised gas mass flow rate through concentric circles of decreasing radii around the nucleus resulting in mass inflow rates ranging from 0.4 M_sun/yr at 300pc down to 0.2 M_sun/yr at 100pc from the nucleus. These rates are larger than necessary to power the active nucleus.Comment: 10 pages, 10 figures, accepted for publication in MNRA

Development of High Thermal Stability Geopolymer Composites Enhanced by Nano Metakaolin

This paper deals with study of thermal stability of geopolymer composites enhanced by nano metakaolin materials (NMK) and exposed to high firing temperature up to 1000 °C. The main geopolymer made up of water cooled slag having various kaolin ratios.  The activators used are Na2SiO3 and NaOH in the ratio of 3:3. The thermo-physical, micro-structural and mechanical properties of the geopolymers before and after the exposure to elevated temperatures of 300, 500, 600 800 and 1000 °C have been investigated. The fire shrinkage of the geopolymer specimens increased by increasing temperature up to 1000 oC. Also, the fire shrinkage increased slowly up to 500 °C. The mechanical strength of geopolymer specimens increased with temperature up to 500 oC. The good thermo-physical and mechanical properties for these geopolymer composites increase the possibility of vast application of these eco-friendly materials in construction sectors