5,121 research outputs found

    Land Markets, Employment, and Resource Use in the Peri-Urban Green Zones of Maputo, Mozambique: A Case Study of Land Market Rigidities and Institutional Constraints to Economic Growth

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    Beginning in January 1991, the U.S. Agency for International Development funded a series of studies on land, employment, and financial markets in the peri-urban areas of Maputo. Beginning in September 1991, a land-market survey involving 121 households and 162 plots of land was administered in two peri-urban green zones of Maputo-districts 4 and 6. Households were queried about their land-settlement histories, mode of land acquisition, terms and conditions of transfer, land rights, size of holdings, perceptions of tenure security, land-use practices, commercial input use, hired labor, agricultural sales and revenues, nonfarm employment and earnings, and general demographic characteristics. The present study reports findings from the land-market survey along with numerous other interviews with producers, buyers and sellers of land, local authorities, and district and national officials in Maputo and its surrounding peri-urban green zones. Section 1 is introductory while section 2 covers the legal foundation of land tenure and describes the various authorities and agencies responsible for setting and enforcing land policy in the peri-urban zone. Section 3 explains the research design and sampling frame used to select households and landholdings for the study, choice of strata, survey instruments, research questions, and data limitations. Section 4 provides a statistical profile of the household economy while section 5 examines processes of land settlement, land acquisition, types and sources of land dispute, and registration benefits. In section 6, economic and political factors are linked with land prices to explain the determination of "reservation" and "offer" prices of land and to evaluate the influence of market factors and Possible asymmetries in information and bargaining position on land-price perceptions.Land Economics/Use,

    Thermodynamic Properties of the Spin-1/2 Antiferromagnetic ladder Cu2(C2H12N2)2Cl4 under Magnetic Field

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    Specific heat (CVC_V) measurements in the spin-1/2 Cu2_2(C2_2H12_{12}N2_2)2_2Cl4_4 system under a magnetic field up to H=8.25TH=8.25 T are reported and compared to the results of numerical calculations based on the 2-leg antiferromagnetic Heisenberg ladder. While the temperature dependences of both the susceptibility and the low field specific heat are accurately reproduced by this model, deviations are observed below the critical field HC1H_{C1} at which the spin gap closes. In this Quantum High Field phase, the contribution of the low-energy quantum fluctuations are stronger than in the Heisenberg ladder model. We argue that this enhancement can be attributed to dynamical lattice fluctuations. Finally, we show that such a Heisenberg ladder, for H>HC1H>H_{C1}, is unstable, when coupled to the 3D lattice, against a lattice distortion. These results provide an alternative explanation for the observed low temperature (TC0.5KT_C\sim 0.5K -- 0.8K0.8K) phase (previously interpreted as a 3D magnetic ordering) as a new type of incommensurate gapped state.Comment: Minor changes, list of authors complete

    IMPACTS OF POLICY REFORMS ON THE SUPPLY OF MEXICAN LABOR TO U.S. FARMS: NEW EVIDENCE FROM MEXICO

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    The availability of immigrant farmworkers from Mexico critically shapes fruit, vegetable, and horticultural (FVH) production in the United States. We test the impact of recent policy reforms on the supply of Mexican labor to U.S. farms, using a 2-way fixed effects model and new data from rural Mexico.Labor and Human Capital,

    Legal Uncertainty and Land Disputes in the Peri-Urban Areas of Mozambique: Land Markets in Transition

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    The Government of Mozambique is considering legal changes in its land law and administration of state leasehold property-an enormous challenge given its past socialist history and the uncertainties created by its current transition to a private market economy. The present research sought to identify dispute causes and de facto processes of dispute resolution as one basis for gauging inadequacies in the current law and system of state land administration.Land Economics/Use,

    Flight demonstration of laser diode initiated ordnance

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    A program has been initiated by NASA Headquarters to validate laser initiated ordnance in flight applications. The primary program goal is to bring together a team of government and industry members to develop a laser initiated ordnance system having the test and analysis pedigree to be flown on launch vehicles. The culmination of this effort was a flight of the Pegasus launch vehicle which had two fin rockets initiated by this laser system. In addition, a laser initiated ordnance squib was fired into a pressure bomb during thrusting flight. The complete ordnance system comprising a laser diode firing unit, fiber optic cable assembly, laser initiated detonator, and laser initiated squib was designed and built by The Ensign Bickford Company. The hardware was tested to the requirements of the Pegasus launch vehicle and integrated into the vehicle by The Ensign Bickford Company and the Orbital Sciences Corporation. Discussions include initial program concept, contract implementation, team member responsibilities, analysis results, vehicle integration, safing architecture, ordnance interfaces, mission timeline and telemetry data. A complete system description, summary of the analyses, the qualification test results, and the results of flight are included

    On the Asymptotic Stability of De-Sitter Spacetime: a non-linear perturbative approach

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    We derive evolution and constraint equations for second order perturbations of flat dust homogeneous and isotropic solutions to the Einstein field equations using all scalar, vector and tensor perturbation modes. We show that the perturbations decay asymptotically in time and that the solutions converge to the De-Sitter solution. By induction, this result is valid for perturbations of arbitrary order. This is in agreement with the cosmic no-hair conjecture of Gibbons and Hawking.Comment: 11 pages, 2 figure

    Stable Isotropic Cosmological Singularities in Quadratic Gravity

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    We show that, in quadratic lagrangian theories of gravity, isotropic cosmological singularities are stable to the presence of small scalar, vector and tensor inhomogeneities. Unlike in general relativity, a particular exact isotropic solution is shown to be the stable attractor on approach to the initial cosmological singularity. This solution is also known to act as an attractor in Bianchi universes of types I, II and IX, and the results of this paper reinforce the hypothesis that small inhomogeneous and anisotropic perturbations of this attractor form part of the general cosmological solution to the field equations of quadratic gravity. Implications for the existence of a 'gravitational entropy' are also discussed.Comment: 18 pages, no figure

    Study on the neuronal circuits implicated in postural tremor and hypokinesia

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    The effect of various tegmentary lesions at the level of the pontomesenchphalon in monkeys on motor function was observed. The importance of the monoaminergic mechanisms of the brainstem is discussed. The results also show the importance of the descending tegmentary rubral system and the rubroolivocerebellar circuit in controlling peripheral motor activity. The destruction of the sensory motor cortex proves to be a more effective way of eliminating spontaneous or harmaline induced tremor than the complete interruption of the pyramidal system on the level of the cerebral peduncle

    Quantum internal modes of solitons in 1d easy-plane antiferromagnet in strong magnetic field

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    In presence of a strong external magnetic field the dynamics of solitons in a one-dimensional easy-plane Heisenberg antiferromagnet exhibits a number of peculiarities. Dynamics of internal soliton degrees of freedom is essentially quantum, and they are strongly coupled to the "translational" mode of soliton movement. These peculiarities lead to considerable changes in the response functions of the system which can be detected experimentally.Comment: 8 pages, RevTeX, 6 figures, uses psfig.sty, submitted to PR
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