8,721 research outputs found

    A survey of the problem and research needs in the coastal zone

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    Coastal zone oceanography emphasizing pollution and geological processes - bibliograph

    Spectral and stratigraphic mapping of hydrated sulfate and phyllosilicate-bearing deposits in northern Sinus Meridiani, Mars

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    We present detailed stratigraphic and spectral analyses that focus on a region in northern Sinus Meridiani located between 1°N to 5°N latitude and 3°W to 1°E longitude. Several stratigraphically distinct units are defined and mapped using morphologic expression, spectral properties, and superposition relationships. Previously unreported exposures of hydrated sulfates and Fe/Mg smectites are identified using MRO CRISM and MEX OMEGA near‐infrared (1.0 to 2.5 ”m) spectral reflectance observations. Layered deposits with monohydrated and polyhydrated sulfate spectral signatures that occur in association with a northeast‐southwest trending valley are reexamined using highresolution CRISM, HiRISE, and CTX images. Layers that are spectrally dominated by monohydrated and polyhydrated sulfates are intercalated. The observed compositional layering implies that multiple wetting events, brine recharge, or fluctuations in evaporation rate occurred. We infer that these hydrated sulfate‐bearing layers were unconformably deposited following the extensive erosion of preexisting layered sedimentary rocks and may postdate the formation of the sulfate‐ and hematite‐bearing unit analyzed by the MER Opportunity rover. Therefore, at least two episodes of deposition separated by an unconformity occurred. Fe/Mg phyllosilicates are detected in units that predate the sulfateand hematite‐bearing unit. The presence of Fe/Mg smectite in older units indicates that the relatively low pH formation conditions inferred for the younger sulfate‐ and hematitebearing unit are not representative of the aqueous geochemical environment that prevailed during the formation and alteration of earlier materials. Sedimentary deposits indicative of a complex aqueous history that evolved over time are preserved in Sinus Meridiani, Mars

    ICT entertainment appliances’ impact on domestic electricity consumption

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    Increased electricity consumption and environmental impacts of Information Communication Technology (ICT) have been subjects of research since the 1990s. This paper focuses on consumer electronics in households, in particular TVs, computers and their peripherals. ICT accounts for almost 15% of global domestic electricity use, including waste energy from devices left on standby which is estimated in the EU-27 to contribute 6% of residential energy demand. In Europe, the household electricity consumption from small electronic appliances, including ICT, increased by 2.5 times in 2011 compared to 1990. Similarly, in the UK, energy demand from electronic devices accounted for 23% of total household electricity use in 2012, compared to 12% in 1990. This is an outcome of the market saturation of new, cheaper ICT entertainment devices, facilitated by marketing strategies which identify new needs for consumers, as charted by the review of market growth in this paper. New increasingly portable laptops, smart phones and tablets with wireless connectivity allow householders to perform a wider range of activities in a wider range of locations throughout the home, such as social networking while the television is active. We suggest that policies which consider how to increase the energy efficiency of ICT devices alone are unlikely to be successful since effective strategies need to address how the drivers which have developed around the use of ICT can be adapted in order to conserve electricity in households. A range of policy solutions are discussed, including feedback, public information campaigns, environmental education, energy labelling, bans of, or taxation on the least efficient products as well as the use of a TV as central hub to perform the existing functions of multiple devices

    Creation and manipulation of Feshbach resonances with radio-frequency radiation

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    We present a simple technique for studying collisions of ultracold atoms in the presence of a magnetic field and radio-frequency radiation (rf). Resonant control of scattering properties can be achieved by using rf to couple a colliding pair of atoms to a bound state. We show, using the example of 6Li, that in some ranges of rf frequency and magnetic field this can be done without giving rise to losses. We also show that halo molecules of large spatial extent require much less rf power than deeply bound states. Another way to exert resonant control is with a set of rf-coupled bound states, linked to the colliding pair through the molecular interactions that give rise to magnetically tunable Feshbach resonances. This was recently demonstrated for 87Rb [Kaufman et al., Phys. Rev. A 80:050701(R), 2009]. We examine the underlying atomic and molecular physics which made this possible. Lastly, we consider the control that may be exerted over atomic collisions by placing atoms in superpositions of Zeeman states, and suggest that it could be useful where small changes in scattering length are required. We suggest other species for which rf and magnetic field control could together provide a useful tuning mechanism.Comment: 21 pages, 8 figures, submitted to New Journal of Physic

    Bactrocera Cucurbitae response to four Cymbopogon species essential oils

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    GC/MS analysis of essential oils extracted from four Cymbopogon species revealed that the majors compounds were trans-p-mentha-1(7),8-dien-2-ol (21.9%), cis-p-mentha-1(7),8-den- 2-ol (19.4%), trans-p-mentha-2,8-dien-1-ol (9.6%), cis-p-mentha-2,8-dien-1-ol (7.2%), cis-pmenth-2-en-1-ol (7.2%), limonene (6.3%) in C. giganteus; piperitone (68.4%); ?-2-carene (11.5%) and ?-eudesmol (4.9%) in C. schoenanthus, while citronellal (41.6%); geraniol (28.2%); citronellol (12.6%) and geranial (41.3%); neral (33.0%); myrcene (10.4%), geraniol (6.5%) were recorded in C. nardus and C. citratus, respectively.Tephritid fruit flies use both olfactory and visual cues to seek food and ovipositional resources. Olfactive effects for C. citratus, C. nardus, C. giganteus and C. schoenanthus essential oils on melon fly (B. cucurbitae) were evaluated using a four-arm olfactometer. The results showed that C. giganteus and C. schoenanthus repel mostly the fruit fly B. cucurbitae, compared with C. nardus and C. citratus and that female and male B. cucurbitae responded similarly to odours emitted from all essential oils evaluated. The number of pupae collected from zucchini treated with C. giganteus was significantly lower than that collected from zucchini treated with C. nardus when exposed to female B. cucurbitae, regardless of the concentrations

    Rotating strings

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    Analytical expressions are provided for the configurations of an inextensible, flexible, twistable inertial string rotating rigidly about a fixed axis. Solutions with trivial radial dependence are helices of arbitrary radius and pitch. Non-helical solutions are governed by a cubic equation whose roots delimit permissible values of the squared radial coordinate. Only curves coplanar with the axis of rotation make contact with it.Comment: added to discussion and made small revisions to tex

    Programmed buckling by controlled lateral swelling in a thin elastic sheet

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    Recent experiments have imposed controlled swelling patterns on thin polymer films, which subsequently buckle into three-dimensional shapes. We develop a solution to the design problem suggested by such systems, namely, if and how one can generate particular three-dimensional shapes from thin elastic sheets by mere imposition of a two-dimensional pattern of locally isotropic growth. Not every shape is possible. Several types of obstruction can arise, some of which depend on the sheet thickness. We provide some examples using the axisymmetric form of the problem, which is analytically tractable.Comment: 11 pages, 9 figure

    Composite bosons in bilayer nu = 1 system: An application of the Murthy-Shankar formalism

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    We calculate the dispersion of the out-of-phase mode characteristic for the bilayer nu = 1 quantum Hall system applying the version of Chern-Simons theory of Murthy and Shankar that cures the unwanted bare electron mass dependence in the low-energy description of quantum Hall systems. The obtained value for the mode when d, distance between the layers, is zero is in a good agreement with the existing pseudospin picture of the system. For d nonzero but small we find that the mode is linearly dispersing and its velocity to a good approximation depends linearly on d. This is in agreement with the Hartree-Fock calculations of the pseudospin picture that predicts a linear dependance on d, and contrary to the naive Hartree predictions with dependence on the square-root of d. We set up a formalism that enables one to consider fluctuations around the found stationary point values. In addition we address the case of imbalanced layers in the Murthy-Shankar formalism.Comment: 10 pages, 1 figur

    Incommensurate ground state of double-layer quantum Hall systems

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    Double-layer quantum Hall systems possess interlayer phase coherence at sufficiently small layer separations, even without interlayer tunneling. When interlayer tunneling is present, application of a sufficiently strong in-plane magnetic field B∄>BcB_\parallel > B_c drives a commensurate-incommensurate (CI) transition to an incommensurate soliton-lattice (SL) state. We calculate the Hartree-Fock ground-state energy of the SL state for all values of B∄B_\parallel within a gradient approximation, and use it to obtain the anisotropic SL stiffness, the Kosterlitz-Thouless melting temperature for the SL, and the SL magnetization. The in-plane differential magnetic susceptibility diverges as (B∄−Bc)−1(B_\parallel - B_c)^{-1} when the CI transition is approached from the SL state.Comment: 12 pages, 7 figures, to be published in Physical Review
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