Costs and benefits of rural-urban migration : evidence from India

This paper provides new evidence on rural-urban migration decisions in developing countries. Using original survey data from rural India, we show that seasonal migrants prefer to earn 35 percent less on local public works rather than incur the cost of migrating. Structural estimates suggest that the fixed cost of migration is small, and can be entirely explained by travel costs and income risk. In contrast, the flow cost of migration is high. We argue that higher living costs in the city explain only a small part of the flow cost of migration and that most of it is non-monetary

Equilibrium Distributional Impacts of Government. Employment Programs: Evidence from India's Employment Guarantee

This paper presents evidence on the equilibrium labor market impacts of a large rural workfare program in India. We use the gradual roll out of the program to estimate changes in districts that received the program earlier relative to those that received it later. Our estimates reveal that following the introduction of the program, public employment increased by .3 days per prime-aged person per month (1.3% of private sector employment) more in early districts than in the rest of India. Casual wages increased by 4.5%, and private sector work for low-skill workers fell by 1.6%. These effects are concentrated in the dry season, during which the majority of public works employment is provided. Our results suggest that public sector hiring crowds out private sector work and increases private sector wages. We use these estimates to compute the implied welfare gains of the program by consumption quintile. Our calculations show that the welfare gains to the poor from the equilibrium increase in private sector wages are large in absolute terms and large relative to the gains received solely by program participants. We conclude that the equilibrium labor market impacts are a first order concern when comparing workfare programs with other anti-poverty programs such as a cash transfer

Costs and benefits of seasonal migration : evidence from India

This paper provides new evidence on rural-to-urban migration decisions in developing countries. Using original survey data from rural India, we show that employment provision on local public works significantly reduces seasonal migration. Workers who choose to participate in the program forgo much higher earnings outside of the village. Structural estimates imply that the utility cost of one day away may be as high as 60% of migration earnings. Up to half of this cost can be explained by higher living costs and income risk. The other half likely reflects high non-monetary costs from living and working in the city

Short-term migration rural workfare programs and urban labor markets - evidence from India

This paper provides some of the first evidence that rural development policies can have fundamental effects on the reallocation of labor between rural and urban areas. It studies the spillover effects of the world's largest rural workfare program, India's rural employment guarantee. We find that the workfare program has substantial consequences: it reduces short-term (or seasonal) migration to urban areas by 9% and increases wages for manual, short-term work in urban areas by 6%. The implied elasticity of unskilled wages with respect to short-term migration is high (-0.7)

Short-range force detection using optically-cooled levitated microspheres

We propose an experiment using optically trapped and cooled dielectric microspheres for the detection of short-range forces. The center-of-mass motion of a microsphere trapped in vacuum can experience extremely low dissipation and quality factors of $10^{12}$, leading to yoctonewton force sensitivity. Trapping the sphere in an optical field enables positioning at less than 1 $\mu$m from a surface, a regime where exotic new forces may exist. We expect that the proposed system could advance the search for non-Newtonian gravity forces via an enhanced sensitivity of $10^5-10^7$ over current experiments at the 1 $\mu$m length scale. Moreover, our system may be useful for characterizing other short-range physics such as Casimir forces.Comment: 4 pages, 3 figures, minor changes, Figs. 1 and 2 replace

Moving From Dumb To Smart Classrooms: Technology Options And Implementation Issues

What are “Smart Classrooms” and why do we need them? What technology components are necessary for a smart classroom, and what are the implementation challenges

Direct Kerr-frequency-comb atomic spectroscopy

Microresonator-based soliton frequency combs - microcombs - have recently emerged to offer low-noise, photonic-chip sources for optical measurements. Owing to nonlinear-optical physics, microcombs can be built with various materials and tuned or stabilized with a consistent framework. Some applications require phase stabilization, including optical-frequency synthesis and measurements, optical-frequency division, and optical clocks. Partially stabilized microcombs can also benefit applications, such as oscillators, ranging, dual-comb spectroscopy, wavelength calibration, and optical communications. Broad optical bandwidth, brightness, coherence, and frequency stability have made frequency-comb sources important for studying comb-matter interactions with atoms and molecules. Here, we explore direct microcomb atomic spectroscopy, utilizing a cascaded, two-photon 1529-nm atomic transition of rubidium. Both the microcomb and the atomic vapor are implemented with planar fabrication techniques to support integration. By fine and simultaneous control of the repetition rate and carrier-envelope-offset frequency of the soliton microcomb, we obtain direct sub-Doppler and hyperfine spectroscopy of the $4^2D_{5/2}$ manifold. Moreover, the entire set of microcomb modes are stabilized to this atomic transition, yielding absolute optical-frequency fluctuations of the microcomb at the kilohertz-level over a few seconds and < 1 MHz day-to-day accuracy. Our work demonstrates atomic spectroscopy with microcombs and provides a rubidium-stabilized microcomb laser source, operating across the 1550 nm band for sensing, dimensional metrology, and communication.Comment: 5 pages, 3 figure

Ultra-efficient frequency comb generation in AlGaAs-on-insulator microresonators

Recent advances in nonlinear optics have revolutionized integrated photonics, providing on-chip solutions to a wide range of new applications. Currently, state of the art integrated nonlinear photonic devices are mainly based on dielectric material platforms, such as Si₃N₄ and SiO₂. While semiconductor materials feature much higher nonlinear coefficients and convenience in active integration, they have suffered from high waveguide losses that prevent the realization of efficient nonlinear processes on-chip. Here, we challenge this status quo and demonstrate a low loss AlGaAs-on-insulator platform with anomalous dispersion and quality (Q) factors beyond 1.5 × 10⁶. Such a high quality factor, combined with high nonlinear coefficient and small mode volume, enabled us to demonstrate a Kerr frequency comb threshold of only ∼36 µW in a resonator with a 1 THz free spectral range, ∼100 times lower compared to that in previous semiconductor platforms. Moreover, combs with broad spans (>250 nm) have been generated with a pump power of ∼300 µW, which is lower than the threshold power of state-of the-art dielectric micro combs. A soliton-step transition has also been observed for the first time in an AlGaAs resonator

Use of levosimendan in acute heart failure

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