1,410 research outputs found
Resource Competition Among the Uinta Basin Fremont
Archaeologists describe the Uinta Fremont (A.D. 0 – 1300) as a mixed foraging-farming society that underwent a dramatic social change from A.D. 700 – 1000. Researchers observe through different architectural styles and subsistence activity a change from large, aggregated settlements to more dispersed and defensively oriented villages and hamlets. The Ideal Free Distribution (IFD) model provides an explanatory framework through which to interpret these changes. IFD predicts the order in which people or animals will occupy habitats based on a habitat’s relative suitability and suggests hypothetical behaviors that people or animals might engage in to improve or maintain the relative suitability of a habitat. One prediction of IFD is that behaviors indicating resource competition will become more frequent when population density increases. I test whether this hypothesis explains changes in storage features by considering storage behavior as a manifestation of resource competition, and I investigate whether storage feature frequency correlates with periods of Fremont population increases and paleoenvironmental degradation.
These tests explain aspects of Fremont culture change and suggest future research possibilities. Storage feature frequency, representing resource competition, remains low from A.D. 0 – 700, suggesting that the habitats could absorb growing Fremont populations. After A.D. 700, however, resource competition rose and remained high, a condition that likely spurred the defensive architecture and dispersed settlements that became increasingly common after A.D. 1000. The successes and limitations of applying IFD to the archaeological record point the way toward future uses of the model to investigate settlement spacing and reaffirm the use of radiocarbon data in archaeological science
Maxwell-Chern-Simons vortices in a CPT-odd Lorentz-violating Higgs Electrodynamics
We have studied BPS vortices in a CPT-odd and Lorentz-violating
Maxwell-Chern-Simons-Higgs (MCSH) electrodynamics attained from the dimensional
reduction of the Carroll-Field-Jackiw-Higgs model. The Lorentz-violating
parameter induces a pronounced behavior at origin (for the magnetic/electric
fields and energy density) which is absent in the MCSH vortices. For some
combination of the Lorentz-violating coefficients there always exist a
sufficiently large winding number such that for all
the magnetic field flips its signal, yielding two well defined regions with
opposite magnetic flux. However, the total magnetic flux remains quantized and
proportional to the winding number.Comment: Revtex style, 8 page
Bose Einstein condensation on inhomogeneous amenable graphs
We investigate the Bose-Einstein Condensation on nonhomogeneous amenable
networks for the model describing arrays of Josephson junctions. The resulting
topological model, whose Hamiltonian is the pure hopping one given by the
opposite of the adjacency operator, has also a mathematical interest in itself.
We show that for the nonhomogeneous networks like the comb graphs, particles
condensate in momentum and configuration space as well. In this case different
properties of the network, of geometric and probabilistic nature, such as the
volume growth, the shape of the ground state, and the transience, all play a
role in the condensation phenomena. The situation is quite different for
homogeneous networks where just one of these parameters, e.g. the volume
growth, is enough to determine the appearance of the condensation.Comment: 43 pages, 12 figures, final versio
Infrared Observations of the Helix Planetary Nebula
We have mapped the Helix (NGC 7293) planetary nebula (PN) with the IRAC instrument on the Spitzer Space Telescope. The Helix is one of the closest bright PNs and therefore provides an opportunity to resolve the small-scale structure in the nebula. The emission from this PN in the 5.8 and 8 μm IRAC bands is dominated by the pure rotational lines of molecular hydrogen, with a smaller contribution from forbidden line emission such as [Ar III] in the ionized region. The IRAC images resolve the "cometary knots," which have been previously studied in this PN. The "tails" of the knots and the radial rays extending into the outer regions of the PN are seen in emission in the IRAC bands. IRS spectra on the main ring and the emission in the IRAC bands are consistent with shock-excited H_2 models, with a small (~10%) component from photodissociation regions. In the northeast arc, the H_2 emission is located in a shell outside the Hα emission
Modelling of Dynamic Strain Aging with a Dislocation-Based Isotropic Hardening Model and Investigation of Orthogonal Loading
Based on experimental results, a dislocation material model describing the dynamic strain aging\ud
effect at different temperatures is presented. One and two stage loading tests were performed in\ud
order to investigate the influence of the loading direction as well as the temperature influence due\ud
to the hardening mechanism. Bergström’s theory of work hardening was used as a basis for the\ud
model development regarding the thermal isotropic behavior as well as the Chaboche model to\ud
describe the kinematic hardening. Both models were implemented in an in-house FE-Code in\ud
order to simulate the real processes. The present paper discusses two hardening mechanisms,\ud
where the first part deals with the pure isotropic hardening including dynamic strain aging and the\ud
second part involves the influence of the loading direction regarding combined (isotropic and\ud
kinematic) hardening behavior
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