11,708 research outputs found

    Sherlock: An Automated Follow-Up Telescope for Wide-Field Transit Searches

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    The most significant challenge currently facing photometric surveys for transiting gas-giant planets is that of confusion with eclipsing binary systems that mimic the photometric signature. A simple way to reject most forms of these false positives is high-precision, rapid-cadence monitoring of the suspected transit at higher angular resolution and in several filters. We are currently building a system that will perform higher-angular-resolution, multi-color follow-up observations of candidate systems identified by Sleuth (our wide-field transit survey instrument at Palomar), and its two twin system instruments in Tenerife and northern Arizona.Comment: 4 pages, 3 figures, to appear in AIP Conf Proc: The Search for Other Worlds, eds. S. S. Holt & D. Demin

    Rice research, technological progress, and impacts on the poor: the Bangladesh case (summary report)

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    "This case study builds on an ongoing large-scale quantitative research project undertaken by BIDS/IRRI since 1987 originally in 64 unions from 57 districts of the country. It adds a qualitative research component to examine the impact of modern rice varieties (MVs) on livelihoods in a structured sample of eight of these villages across a range of favorable and unfavorable contexts..... The quantitative research shows that for households with access to land there have been direct adoption impacts in the form of increased yields and higher profits. However, since rice now only represents around 20 percent of most households' overall income, nonagricultural income is found to have gained dramatically in importance for rural households. While the profitability has declined over time, rice contributes to improved food security and provides a “springboard” for both rich and poor farm households moving into nonfarm income generation and employment... The qualitative research component generally confirmed these general findings, highlighting other factors such as the improved status associated with fixed-rent tenancy and “contract” labor arrangements. The qualitative research also shows negative adoption impacts such as shrinking common property resources (wild fish, vegetables, etc., and declining soil fertility, both of which may increase the long-term vulnerability of the poor. It also throws light on the processes of technology dissemination.... It was found that the linking of qualitative and quantitative research methodologies was useful in (a) generating complementary data of different kinds on similar issues and (b) generating new data missed within a purely quantitative approach. The sustainable livelihoods framework was a useful, flexible tool for structuring the qualitative data collection and analysis. However, the research study as a whole was limited by the fact that the qualitative component was “bolted onto” a quantitative study already underway. Therefore the framework, and the various data collection methodologies, were not systematically integrated across both components of the study. In conclusion, future agricultural research on rice may need to further address the question of MV adoption potential on risk-prone lands, the relevance of existing technology dissemination systems, the relationship between MV adoption and crop diversification, and the challenges of more sustainable crop management techniques." Authors' AbstractRice Bangladesh,

    PUBLIC CONSERVATION LAND AND EMPLOYMENT GROWTH IN THE NORTHERN FOREST REGION

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    As with many environmental issues, debates about increasing public conservation lands in the Northern Forest region frequently center on a perceived tradeoff between jobs and the environment. In particular, opponents of conservation lands often argue that employment will decline significantly when land is diverted from commodity-oriented uses such as wood products production. To evaluate this claim, we estimate a model of simultaneous employment and net migration growth using data on the 92 non-metropolitan counties comprising the region. Growth in employment and net migration are measured over the period 1990 to 1997 and the set of exogenous variables includes the 1990 share of the county land base in public conservation uses. We find that net migration rates were systematically higher in counties with more conservation lands, but the effects are relatively small. Public conservation lands were found to have no systematic effect on employment growth over the 1990 to 1997 period. Two extensions are considered. We examine the separate effects of preservationist and multiple-use lands. We also identify a "natural experiment" involving changes in national forest management that allows us to estimate the effects of diverting private forestland to public conservation uses. Our central conclusions are that existing public conservation lands have a positive, but small, effect on employment and migration in the Northern Forest region and that, over the range of our data, employment and migration are unlikely to be affected by timber harvest reductions resulting from the establishment of new conservation lands.Labor and Human Capital, Land Economics/Use,

    Spatial Externalities in Agriculture: Empirical Analysis, Statistical Identification, and Policy Implications

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    Spatial externalities can affect economic welfare and landscape pattern by linking farm returns on adjoining parcels of land. While policy can be informed by research that documents spatial externalities, statistically quantifying the presence of externalities from landscape pattern is insufficient for policy guidance unless the underlying cause of the externality can be identified as positive or negative. This article provides a springboard for empirical research by examining the underlying structure, social-environmental interactions, and statistical identification strategies for the analysis and quantification of agricultural spatial externalities that are derived from observations of landscape change. The potential for original policy treatments of agricultural spatial externalities in development and environment outcomes are highlighted.

    A High-Level Disinfection Standard for Land-Applied Sewage Sludges (Biosolids)

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    associated with land-applied sewage sludges primarily involve irritation of the skin, mucous membranes, and the respiratory tract accompanied by opportunistic infections. Volatile emissions and organic dusts appear to be the main source of irritation. Occasionally, chronic gastrointestinal problems are reported by affected residents who have private wells. To prevent acute health effects, we recommend that the current system of classifying sludges based on indicator pathogen levels (Class A and Class B) be replaced with a single high-level disinfection standard and that methods used to treat sludges be improved to reduce levels of irritant chemicals, especially endotoxins. A national opinion survey of individuals impacted by or concerned about the safety of land-application practices indicated that most did not consider the practice inherently unsafe but that they lacked confidence in research supported by federal and state agencie

    Three-dimensional cell to tissue assembly process

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    The present invention relates a 3-dimensional cell to tissue and maintenance process, more particularly to methods of culturing cells in a culture environment, either in space or in a gravity field, with minimum fluid shear stress, freedom for 3-dimensional spatial orientation of the suspended particles and localization of particles with differing or similar sedimentation properties in a similar spatial region

    Modeling of permanent magnets: Interpretation of parameters obtained from the Jiles–Atherton hysteresis model

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    The Jiles–Atherton theory is based on considerations of the dependence of energy dissipation within a magnetic material resulting from changes in its magnetization. The algorithm based on the theory yields five computed model parameters, M S , a, α, k, and c, which represent the saturation magnetization, the effective domain density, the mean exchange coupling between the effective domains, the flexibility of domain walls and energy‐dissipative features in the microstructure, respectively. Model parameters were calculated from the algorithm and linked with the physical attributes of a set of three related melt‐quenched permanent magnets based on the Nd2Fe14B composition. Measured magnetic parameters were used as inputs into the model to reproduce the experimental hysteresis curves. The results show that two of the calculated parameters, the saturation magnetization M S and the effective coercivityk, agree well with their directly determined analogs. The calculated a and α parameters provide support for the concept of increased intergranular exchange coupling upon die upsetting, and decreased intergranular exchange coupling with the addition of gallium
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