5,716 research outputs found

    How ‘ya gonna keep ‘em down on the farm -After they’ve seen Paree

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    Change is abroad across the land, as often destructive as constructive. No one is immune. The financial crisis is perhaps the most obvious wave of change, but as the title of this paper (and also the title of a song popular in America between World I and World War II1) suggests, the most pervasive, seductive, and subversive changes are fueled by the view of the wider world provided by the internet with its blogs and social networks. How ‘ya gonna keep‘em satisfied with a second-class life (or worse) after they have seen the luxuries and freedoms of the wider world? Knowledge is power, and frightening amounts of people-power can be marshaled via the internet. Tyrants fall and royal families quake in the face of so much focused intentionality. But even as freedoms are recovered, what are all the unemployed to do with that freedom, especially in those countries in which the average age is between late teens and early twenties – kids, really, with no prospects of the good life? Add to this the coming shortage of food, drinking water, and fuel and the resulting upward spiral of costs for life’s necessities, further imposing hardship on new members of ‘the internet generation.’ Social and political catastrophes are to be expected. What can the countries in ‘Europe’s southern neighborhood’ do to respond, to be proactive in the face of massive and predictable changes?predictable problems, proactive response, cross-border collaboration, food, fuel riots

    Incoherent dynamics in neutron-matter interaction

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    Coherent and incoherent neutron-matter interaction is studied inside a recently introduced approach to subdynamics of a macrosystem. The equation describing the interaction is of the Lindblad type and using the Fermi pseudopotential we show that the commutator term is an optical potential leading to well-known relations in neutron optics. The other terms, usually ignored in optical descriptions and linked to the dynamic structure function of the medium, give an incoherent contribution to the dynamics, which keeps diffuse scattering and attenuation of the coherent beam into account, thus warranting fulfilment of the optical theorem. The relevance of this analysis to experiments in neutron interferometry is briefly discussed.Comment: 15 pages, revtex, no figures, to appear in Phys. Rev.

    Thermodynamic Entropy And The Accessible States of Some Simple Systems

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    Comparison of the thermodynamic entropy with Boltzmann's principle shows that under conditions of constant volume the total number of arrangements in simple thermodynamic systems with temperature-independent heat capacities is TC/k. A physical interpretation of this function is given for three such systems; an ideal monatomic gas, an ideal gas of diatomic molecules with rotational motion, and a solid in the Dulong-Petit limit of high temperature. T1/2 emerges as a natural measure of the number of accessible states for a single particle in one dimension. Extension to N particles in three dimensions leads to TC/k as the total number of possible arrangements or microstates. The different microstates of the system are thus shown a posteriori to be equally probable, with probability T-C/k, which implies that for the purposes of counting states the particles of the gas are distinguishable. The most probable energy state of the system is determined by the degeneracy of the microstates.Comment: 9 pages, 1 figur

    The Orbits of Meteorites from Natural Thermoluminescence

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    The natural thermoluminescence (TL) of meteorites reflects their irradiation and thermal histories. Virtually all ordinary chondrites have been irradiated long enough to reach saturation natural TL levels, and thus natural TL levels in these meteorites are determined largely by thermal history. The primary heat source for most meteorites is the Sun, and thus natural TL levels are determined primarily by the closest approach to the Sun, i.e., perihelion. By converting natural TL levels to perihelia, using an assumed albedo typical of meteoroid bodies, it is found that most ordinary chondrites had perihelia of 0.85 to 1.0 AU prior to reaching Earth. This range is similar to that calculated from meteor and fireball observations. All common classes of ordinary chondrites exhibit similar perihelia distributions; however, H and LL chondrites that fell in the local morning differ in their natural TL distribution from those that fell in the local afternoon or evening. This is consistent with earlier suggestions that time of fall reflects orbital distribution. The data also suggest that the orbits of some of the H chondrites cluster and may have come from a debris 'stream' of meteoroids. If meteorites can exist in "orbital groups," significant changes in the types and number of meteorites reaching Earth could occur on the less than 10(exp 5)-year time scale

    National Transonic Facility: A review of the operational plan

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    The proposed National Transonic Facility (NTF) operational plan is reviewed. The NTF will provide an aerodynamic test capability significantly exceeding that of other transonic regime wind tunnels now available. A limited number of academic research program that might use the NTF are suggested. It is concluded that the NTF operational plan is useful for management, technical, instrumentation, and model building techniques available in the specialized field of aerodynamic analysis and simulation. It is also suggested that NASA hold an annual conference to discuss wind tunnel research results and to report on developments that will further improve the utilization and cost effectiveness of the NTF and other wind tunnels

    Spin waves and spin-state transitions in a ruthenate high-temperature antiferromagnet

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    Ruthenium compounds play prominent roles in materials research ranging from oxide electronics to catalysis, and serve as a platform for fundamental concepts such as spin-triplet superconductivity, Kitaev spin-liquids, and solid-state analogues of the Higgs mode in particle physics. However, basic questions about the electronic structure of ruthenates remain unanswered, because several key parameters (including the Hund's-rule, spin-orbit, and exchange interactions) are comparable in magnitude, and their interplay is poorly understood - partly due to difficulties in synthesizing sizable single crystals for spectroscopic experiments. Here we introduce a resonant inelastic x-ray scattering (RIXS) technique capable of probing collective modes in microcrystals of 4d4d-electron materials. We present a comprehensive set of data on spin waves and spin-state transitions in the honeycomb antiferromagnet SrRu2_{2}O6_{6}, which possesses an unusually high N\'eel temperature. The new RIXS method provides fresh insight into the unconventional magnetism of SrRu2_{2}O6_{6}, and enables momentum-resolved spectroscopy of a large class of 4d4d transition-metal compounds.Comment: The original submitted version of the published manuscript. https://www.nature.com/articles/s41563-019-0327-

    The Economics of Hay Quality

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    Hay quality is often discussed when one considers the viability of cash hay operations. A great deal is known about how production impacts quality and how quality impacts animal performance. This knowledge certainly has economic implications, but the economics of hay quality has primarily been evaluated from the animal performance perspective. Analyzing the economics of hay quality from the cash hay producer’s prospective becomes more difficult due to data limitations. There are approximately 2.5 million acres of hay produced in Kentucky annually. The vast majority of this hay is grass type hay that is produced and fed on beef cattle operations. Higher quality hay production represents a much smaller portion of Kentucky’s hay industry, yet yields much greater value on a per acre basis. While a much larger share of this “upper end” hay production is sold off the farm, most is sold through private treaty, which means sale data is not available. Auction markets are becoming more commonly used in hay marketing and provide greater opportunity to analyze factors that impact hay value
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