9,467 research outputs found

    Using Thermal Infrared Imaging to Estimate Soil Hydraulic Parameters: A Novel Approach

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    In this study, skin temperature measured with a thermal infrared (TIR) camera was used to estimate soil hydraulic parameters. These are the physical properties that control how soils transport and retain water, which are notoriously difficult to measure in the field due to the extreme spatial variability of their values. Laboratory experiments were set up to record surface skin temperature response in a clean soil column using a TIR camera after an artificial wetting event. An array of thermocouples, a net radiometer, heat flux sensor and weather station were used to constrain the TIR data and the energy budget during the experiment. The soil column surface was then wetted with a known amount of water over a controlled time period and the thermal response recorded at five minute intervals over the course of 18 hours. Soil hydraulic parameters were then estimated by fitting a water-energy conservation model (ECH2O) to the observed data using a Levenberg-Marquardt least squares minimization. This inversion of ECH2O was able to estimate soil air entry pressure, soil porosity, and the Brooks-Corey pore size distribution parameter with a relatively high degree of precision. The estimated parameters were compared to several sets of known values based on soil textural classification. Most of the estimates were within the range of standard published values. These results show that soil hydraulic parameter estimation based on TIR skin temperature data could prove to be a fast and useful new tool to characterize the distribution and spatial heterogeneity in soil hydraulic properties at the field scale

    Using Thermal Infrared Imagery To Estimate Soil Hydraulic Parameters: A Novel Approach

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    In this study, skin temperature measured with a thermal infrared (TIR) camera was used to estimate soil hydraulic parameters. These physical properties that control how soils transport and retain water are notoriously difficult to measure in the field due to spatial variability. Laboratory experiments were set up to record surface skin temperature response in a clean soil column using a TIR camera after an artificial wetting event. An array of thermocouples, a net radiometer, heat flux sensor and weather station were used to constrain the TIR data and the energy budget during the experiment. The soil column surface was then wetted with a known amount of water over a controlled time period and the thermal response recorded at five minute intervals over the course of 18 hours. Soil hydraulic parameters were then estimated by fitting a water-energy conservation model (ECH2O) to the observed data using a Marqhart-Levenberg least squares minimization method. The estimated parameters obtained were then compared to several sets of known values based on soil textural classification. This inversion of ECH2O was able to estimate the Brooks-Corey λ for sand with a relatively high degree of precision; however, the inversion was unable to provide reasonable estimates of air entry pressure for sand, air entry pressure for soil, or the Brooks-Corey λ for soil. These results indicate that soil hydraulic parameter estimation based on TIR skin temperature data could potentially be a fast and useful new tool to characterize the distribution and spatial heterogeneity in some soil hydraulic parameters. However, future studies should test the method with dedicated groundwater flow models and accurately account for surface emissivity before conducting field tests

    An efficient new route to dihydropyranobenzimidazole inhibitors of HCV replication.

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    A class of dihydropyranobenzimidazole inhibitors was recently discovered that acts against the hepatitis C virus (HCV) in a new way, binding to the IRES-IIa subdomain of the highly conserved 5' untranslated region of the viral RNA and thus preventing the ribosome from initiating translation. However, the reported synthesis of these compounds is lengthy and low-yielding, the intermediates are troublesome to purify, and the route is poorly structured for the creation of libraries. We report a streamlined route to this class of inhibitors in which yields are far higher and most intermediates are crystalline. In addition, a key variable side chain is introduced late in the synthesis, allowing analogs to be easily synthesized for optimization of antiviral activity

    Deterministic quantum state transfer of atoms in a random magnetic field

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    We propose a method for transferring atoms to a target quantum state for a multilevel quantum system with sequentially increasing, but otherwise unknown, energy splitting. This is achieved with a feedback algorithm that processes off-resonant optical measurements of state populations during adiabatic rapid passage in real-time. Specifically, we reliably perform the transfer ∣F=2,mF=2⟩→∣1,1⟩→∣2,1⟩|F=2,m_F=2\rangle \rightarrow |1,1\rangle \rightarrow |2,1\rangle for a sample of ultracold 87^{87}Rb in the presence of a random external magnetic field

    Algebraic properties of generalized Rijndael-like ciphers

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    We provide conditions under which the set of Rijndael functions considered as permutations of the state space and based on operations of the finite field \GF (p^k) (p≥2p\geq 2 a prime number) is not closed under functional composition. These conditions justify using a sequential multiple encryption to strengthen the AES (Rijndael block cipher with specific block sizes) in case AES became practically insecure. In Sparr and Wernsdorf (2008), R. Sparr and R. Wernsdorf provided conditions under which the group generated by the Rijndael-like round functions based on operations of the finite field \GF (2^k) is equal to the alternating group on the state space. In this paper we provide conditions under which the group generated by the Rijndael-like round functions based on operations of the finite field \GF (p^k) (p≥2p\geq 2) is equal to the symmetric group or the alternating group on the state space.Comment: 22 pages; Prelim0

    THIRD INTERNATIONAL SYMPOSIUM ON RANAVIRUSES:: ADVANCING THE UNDERSTANDING OF THE THREAT OF RANAVIRUSES TO NORTH AMERICAN HERPETOFAUNA

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    Members of the genus Ranavirus, one of five genera withinthe family Iridoviridae, encompass a group of large, doublestrandedDNA viruses that infect all three classes of ectothermicvertebrates: fish, amphibians, and reptiles. Ranaviruses areglobally emerging pathogens that cause considerable morbidityand mortality among diverse populations. In North America,ranavirus epizootics are regularly reported in wild and culturedfish, amphibian, and reptile populations

    Elliptic Reciprocity

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    The paper introduces the notions of an elliptic pair, an elliptic cycle and an elliptic list over a square free positive integer d. These concepts are related to the notions of amicable pairs of primes and aliquot cycles that were introduced by Silverman and Stange. Settling a matter left open by Silverman and Stange it is shown that for d=3 there are elliptic cycles of length 6. For d not equal to 3 the question of the existence of proper elliptic lists of length n over d is reduced to the the theory of prime producing quadratic polynomials. For d=163 a proper elliptic list of length 40 is exhibited. It is shown that for each d there is an upper bound on the length of a proper elliptic list over d. The final section of the paper contains heuristic arguments supporting conjectured asymptotics for the number of elliptic pairs below integer X. Finally, for d congruent to 3 modulo 8 the existence of infinitely many anomalous prime numbers is derived from Bunyakowski's Conjecture for quadratic polynomials.Comment: 17 pages, including one figure and two table

    Sensitivity of orbiting JEM-EUSO to large-scale cosmic-ray anisotropies

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    The two main advantages of space-based observation of extreme-energy (≳1019\gtrsim 10^{19}~eV) cosmic-rays (EECRs) over ground-based observatories are the increased field of view, and the all-sky coverage with nearly uniform systematics of an orbiting observatory. The former guarantees increased statistics, whereas the latter enables a partitioning of the sky into spherical harmonics. We have begun an investigation, using the spherical harmonic technique, of the reach of \J\ into potential anisotropies in the extreme-energy cosmic-ray sky-map. The technique is explained here, and simulations are presented. The discovery of anisotropies would help to identify the long-sought origin of EECRs.Comment: 7 pages, 6 figures. To appear in the proceedings of the Cosmic Ray Anisotropy Workshop, Madison Wisconsin, September 201
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