3,242 research outputs found

    Chemistry and Apparent Quality of Surface Water and Ground Water Associated with Coal Basins

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    Personnel of the Arkansas Mining and Mineral Resources Research Institute conducted preliminary investigations on the chemistry and quality of surface and ground water associated with 12 coal-bearing sub-basins in the Arkansas Valley coal field. The coal field is approximately 60 miles long and 33 miles wide but only in 12 areas coal is thick enough and has proper quality to be termed commercial. Both surface and underground sample sites were established in each of the sub-basins with some minor variations in four areas where not all types of sites could be located. Water was collected from 19 surface points and 19 underground points in the established areas. Both field and laboratory analyses were made and elemental contents are reported herein. In the main, the chemistry and water quality suggests that all water is suitable for agricultural and industrial uses. To obtain potable water, treatment must be made to reduce calcium, magnesium, sodium sulfate and iron. The mineral content of the water is due to its contact with coal-bearing zones and, as such, reflects the mineral content of the coal. However, it is recommended that additional studies on the petrography and geochemistry of the coal, overburden and underburden is in order. Also, it is recommended that at least one detailed study be made of one of the coal sub-basins where geologic parameters can be completely established with regard to hydrogeology. This report is an important first step in determining the character and quality of Arkansas coal which must be fully understood to fully utilize this important mineral resource

    Deterministic Secure Communications using Two-Mode Squeezed States

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    We propose a scheme for quantum cryptography that uses the squeezing phase of a two-mode squeezed state to transmit information securely between two parties. The basic principle behind this scheme is the fact that each mode of the squeezed field by itself does not contain any information regarding the squeezing phase. The squeezing phase can only be obtained through a joint measurement of the two modes. This, combined with the fact that it is possible to perform remote squeezing measurements, makes it possible to implement a secure quantum communication scheme in which a deterministic signal can be transmitted directly between two parties while the encryption is done automatically by the quantum correlations present in the two-mode squeezed state.Comment: 10 pages, 4 figure

    {Ba[Au(SCN)2]2}n: a three-dimensional net comprised of monomeric and trimeric gold(I) units

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    The noteworthy structural feature of the title complex, poly[acetonitrile­tetra-μ2-thio­cyanato-barium(II)digold(I)], {[Au2Ba(SCN)4(CH3CN)]}n, is that the bis­(thio­cyanato)­aurate(I) anion adopts both monomeric and trimeric motifs. The trimer unit has an Au⋯Au distance of 3.1687 (3) Å. In both the monomeric and trimeric units, the AuI atoms are also bonded to two S atoms. Within the trimeric unit, the AuI atoms exist in differing environments; one Au atom has a T-shaped three-coordinate geometry while the other has a square-planar four-coordinate geometry. The AuI atom of the monomer adopts a linear two-coordinate geometry. The extended structure can be described as a three-dimensional coordination polymer consisting of chains of Ba atoms bridged by thio­cyanate N atoms. These chains are cross-linked via the gold monomeric and trimeric units

    Genetic analysis of RPA single-stranded DNA binding protein in Haloferax volcanii

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    Replication protein A (RPA) is a single-stranded DNA-binding protein that is present in all three domains of life. The roles of RPA include stabilising and protecting single- stranded DNA from nuclease degradation during DNA replication and repair. To achieve this, RPA uses an oligosaccharide-binding fold (OB fold) to bind single- stranded DNA. Haloferax volcanii encodes three RPAs – RPA1, RPA2 and RPA3, of which rpa1 and rpa3 are in operons with genes encoding associated proteins (APs). The APs belong to the COG3390 group of proteins found in Euryarchaeota and feature an OB fold. Genetic analysis of deletion mutants was employed to determine if all three RPAs are essential for cell viability, and if there is an element of redundancy between RPA1 and RPA3. The hypothesis that the RPAs form a complex with their respective APs, as opposed to a heterotrimeric RPA complex, was also investigated. Furthermore, it was tested whether the RPAs and their respective APs are specific for each other, or whether they are interchangeable. The genetic analysis showed that RPA2 is essential for cell viability, but that neither RPA1 nor RPA3 are. The rpa3, rpa3ap and the rpa3 operon deletion mutants showed sensitivity to DNA damage but only a slight growth defect. By contrast, the rpa1, rpa1ap, rpe and rpa1 operon mutants did not show any DNA damage sensitivity and an even milder growth defect. The double rpa1 rpa3 operon deletion was difficult to generate but unexpectedly lacked a significant DNA damage sensitivity and growth defect. The inability to make the double rpa1 rpa3ap and rpa1ap rpa3 deletion mutants suggests that the APs are specific for their respective RPAs. Biochemical analysis involving histidine-tagged RPAs and APs was used to confirm the conclusions of the genetic analysis. The RPAs did not interact with each other, but instead co-purified with their respective APs. This finding reiterates that the RPAs do not form a heterotrimeric complex, as seen in eukaryotes, but instead form a novel complex with their respective APs

    Tailwater Recovery Systems for Irrigation: Benefit/Cost Analysis and Water Resource Conservation Technique in Northeast Arkansas

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    Water, one of the earth\u27s most vital resources, is particularly significant in the Arkansas Delta agricultural landscape. While both surface and groundwater are extremely important, 94% of the 26.9 billion L (7.1 billion gal) of water pumped daily from the Alluvial Aquifer is used for agricultural purposes. This common property is subsequently being depleted and sustainable conservation methods are being pursued. State and federal incentive programs encourage the use of a tailwater recovery system in agricultural irrigation. With the use of a complete recovery system, benefits include not only government incentives for wetland habitat, but reduced groundwater use and decreased agricultural runoff entering receiving streams. Costs incurred to the farm manager include crop loss due to reservoir storage, additional ditch construction, and the cost of a liftpump. Use of these systems offers not only economic benefits associated with aquifer preservation but also ecological benefits including reduced nutrient and sediment loading to receiving streams concurrent with ecosystem services. The overall benefit/cost analysis ofthese systems shows that the economic benefits of using a tailwater recovery system exceed the cost. Other positive features include the ecological benefits of surface water protection and ecosystem services

    Effective conductivity of 2D isotropic two-phase systems in magnetic field

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    Using the linear fractional transformation, connecting effective conductivities sigma_{e} of isotropic two-phase systems with and without magnetic field, explicit approximate expressions for sigma_{e} in a magnetic field are obtained. They allow to describe sigma_{e} of various inhomogeneous media at arbitrary phase concentrations x and magnetic fields. the x-dependence plots of sigma_e at some values of inhomogeneity and magnetic field are constructed. Their behaviour is qualitatively compatible with the existing experimental data. The obtained results are applicable for different two-phase systems (regular and nonregular as well as random), satisfying the symmetry and self-duality conditions, and admit a direct experimental checking.Comment: 9 pages, 2 figures, Latex2e, small corrections and new figure

    Antarctica on foot: the energy expended to walk, ski and man-haul

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    Polar exploration often involves travelling on foot and thus is physically intensive, with long-term excursions typically resulting in weight loss. Few studies have investigated the energy expended under such circumstances. Here, we present a range of prediction equations for estimating metabolic rate from heart rate or accelerometry data for specific activities including skiing and man-hauling which can be applied to either short- or long-term excursions. We also use some of these equations to estimate the energy expended undertaking various activities by a team of explorers while attempting to traverse the Antarctic continent during the austral winter of 2013 (as part of the White Mars Project during The Coldest Journey). Calibration equations based on either accelerometry data (from which overall dynamic body acceleration, ODBA, is derived) or heart rate showed good relationships with rate of oxygen consumption, particularly when person height was included. Periods of skiing and man- hauling on The Coldest Journey were estimated to be more energetically demanding (30.0 and 31.1 kJ min−1, respectively) than walking (24.9 kJ min−1), or other outdoor work (21.9 kJ min−1). Estimates of energy expenditure during The Coldest Journey were similar to measures obtained in previous, comparative scenarios. We hope that future expeditions to Antarctica will use these prediction equations to further our understanding of the energy costs of exploring Antarctica and the nutritional requirements needed to guard against emaciation
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