49,289 research outputs found

    Application of left- and right-looking SAR stereo to depth measurements of the Ammavaru outflow channel, Lada Terra, Venus

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    Venusian channels are too narrow to be resolved by Magellan's radar altimeter, so they are not visible in the standard topographic data products. Stereo image data, in addition to their benefit to geologic mapping of Venus structures as a whole, are indispensible in measuring the topography across the channels. These measurements can then be used in conjunction with the regional topographic maps based on the altimeter data to produce cross-sectional areas for the channels and estimate the fluid discharge through them. As an example of the application of the stereo image data to venusian channels, a number of test depth and profile measurements were made of the large outflow channel system in Lada Terra, centered at 50 deg S latitude, 21 deg E longitude (F-MIDR 50S021). These measurements were made by viewing the cycle 1 and 2 digital FMIDRs in stereo on a display monitor, so as to minimize the errors in measuring parallax displacement as much as possible. The MIDRs are produced at a scale of 75 m/pixel. This corresponds to a vertical scale of about 17 m/pixel, when calculating the height of a feature from its parallax displacement. An error in placement determination of 1 pixel was assumed to characterize the vertical accuracy as plus or minus 17 m. When this technique was applied to the outflow channel, it was noted that the walls of the collapsed terrain source and 'trough reach' of the channel are laid over in both the cycle 1 and 2 images. This is evident when examining the distance between features on the plateau and the cliff walls in the two images. The layover 'shifts' the features closer to the apparent edge of the wall relative to the oppositely illuminated image

    Should You Stop Investing in a Sinking Fund When it’s Sinking?

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    Irreversible energy flow in forced Vlasov dynamics

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    A recent paper [Phys. Plasmas 20, 032304 (2013)] considered the forced linear Vlasov equation as a model for the quasi-steady state of a single stable plasma wavenumber interacting with a bath of turbulent fluctuations. This approach gives some insight into possible energy flows without solving for nonlinear dynamics. The central result of the present work is that the forced linear Vlasov equation exhibits asymptotically zero (irreversible) dissipation to all orders under a detuning of the forcing frequency and the characteristic frequency associated with particle streaming. We first prove this by direct calculation, tracking energy flow in terms of certain exact conservation laws of the linear (collisionless) Vlasov equation. Then we analyze the steady-state solutions in detail using a weakly collisional Hermite-moment formulation, and compare with numerical solution. This leads to a detailed description of the Hermite energy spectrum, and a proof of no dissipation at all orders, complementing the collisionless Vlasov result.Comment: Small changes for clarit

    Recent trends in US patent grants and issues to be considered

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    The life sciences have changed radically since the Convention on Biological Diversity first opened for signatures in 1992. Traditional organism-based approaches to discovery and use of genetic resources have been supplanted by molecular approaches. Biodiversity prospecting is more likely to be a programmatic bioinformatics activity rather than an activity conducted by field scientists. Access to genetic resources is no longer centered on a hunt for novel species. Rather, the hunt is for novel genes and metabolic pathways that can be cloned into well-understood expression systems and readily scaled-up for industrial production. Information about contemporary research, development, and manufacturing practices needs to be addressed, especially when those genes do not need to be associated with their native host at the time of discovery. Information about the research organizations participating in all phases of the discovery and development process also needs to be considered, especially when it involves partnerships between academic and industrial organizations. 

We present a high-level view of recent trends in the issuance of US patent grants to commercial and non-commercial research organizations, and introduce a technology that is already in place which can be applied to monitoring the use of genetic materials by various stakeholders in an open and transparent manner, as intended under the International Regime for Access and Benefit Sharing (ABS).
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    Habitats and Spider Prey of \u3ci\u3eDipogon Sayi Sayi\u3c/i\u3e (Hymenoptera: Pompilidae) in Washington County, Maine

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    Spider wasps were reared from three types of trap-nests deployed in strip-clearcut areas of a spruce-fir-mixed hardwood forest of Maine. Collections of Dipogon sayi sayi from Mooseborn National Wildlife Refuge, Washington County, represent the easternmost records for the United States. Spider prey included females of Misumena vatia, Xysticus emertoni (new prey record), and X. punctatus, and juveniles and penultimate males of Xysticus sp. We found no evidence of nest-site competition between spider wasps and eumenid wasps (Hymenoptera: Eumenidae) that prey on spruce budwornl, Choristoneura fumiferana, when available nesting sites ranged from 320 to 4400
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