5,716 research outputs found
How âya gonna keep âem down on the farm -After theyâve seen Paree
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 âya gonna keepâem 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 â 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 lifeâs necessities, further imposing hardship on new members of âthe internet generation.â Social and political catastrophes are to be expected. What can the countries in âEuropeâs southern neighborhoodâ 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
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
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
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
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
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Effects of Process Variables and Size Scale on Solidification Microstructure in Laser-Based Solid Freeform Fabrication of Ti-6Al-4V
Mechanical Engineerin
Spin waves and spin-state transitions in a ruthenate high-temperature antiferromagnet
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 -electron materials. We present a comprehensive set of
data on spin waves and spin-state transitions in the honeycomb antiferromagnet
SrRuO, which possesses an unusually high N\'eel temperature. The
new RIXS method provides fresh insight into the unconventional magnetism of
SrRuO, and enables momentum-resolved spectroscopy of a large class
of 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
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 producerâs 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 Kentuckyâs hay industry, yet yields much greater value on a per acre basis. While a much larger share of this âupper endâ 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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