4,280 research outputs found
Orientations of linear stone arrangements in New South Wales
We test the hypothesis that Aboriginal linear stone arrangements in New South
Wales (NSW) are oriented to cardinal directions. We accomplish this by
measuring the azimuths of stone arrangements described in site cards from the
NSW Aboriginal Heritage Information Management System. We then survey a subset
of these sites to test the accuracy of information recorded on the site cards.
We find a preference recorded in the site cards for cardinal orientations among
azimuths. The field surveys show that the site cards are reasonably accurate,
but the surveyors probably did not correct for magnetic declinations. Using
Monte Carlo statistics, we show that these preferred orientations did not occur
by chance and that Aboriginal people deliberately aligned these arrangements to
the approximate cardinal directions. We briefly explore possible reasons for
these preferred orientations and highlight the need for future work.Comment: Australian Archaeology, Volume 75 (December 2012), accepte
Определние предела прочности метаморфического сланца на одноосное сжатие методом упругого отскока
Observations of red-giant variable stars by Aboriginal Australians
Aboriginal Australians carefully observe the properties and positions of
stars, including both overt and subtle changes in their brightness, for
subsistence and social application. These observations are encoded in oral
tradition. I examine two Aboriginal oral traditions from South Australia that
describe the periodic changing brightness in three pulsating, red-giant
variable stars: Betelgeuse (Alpha Orionis), Aldebaran (Alpha Tauri), and
Antares (Alpha Scorpii). The Australian Aboriginal accounts stand as the only
known descriptions of pulsating variable stars in any Indigenous oral tradition
in the world. Researchers examining these oral traditions over the last
century, including anthropologists and astronomers, missed the description of
these stars as being variable in nature as the ethnographic record contained
several misidentifications of stars and celestial objects. Arguably,
ethnographers working on Indigenous Knowledge Systems should have academic
training in both the natural and social sciences.Comment: The Australian Journal of Anthropology (2018
Optimization approaches for the design and operation of open-loop shallow geothermal systems
The optimization of open-loop shallow geothermal systems, which includes both
design and operational aspects, is an important research area aimed at
improving their efficiency and sustainability and the effective management of
groundwater as a shallow geothermal resource. This paper investigates various
approaches to address optimization problems arising from such research
questions. The identified optimization approaches are thoroughly analyzed based
on criteria such as computational efficiency and applicability. Moreover, a
novel classification scheme is introduced that categorizes the approaches
according to the type of groundwater simulation model (numerical or simplified)
and the optimization algorithm used (gradient-based or derivative-free).
Finally, a comprehensive review of existing approaches is provided,
highlighting their strengths and limitations and offering recommendations for
both the use of existing approaches and the development of new ones in this
field.Comment: 16 pages, 3 figures; submitted to Advances in Geoscience
Breakdown of the Luttinger sum-rule at the Mott-Hubbard transition in the one-dimensional t1-t2 Hubbard model
We investigate the momentum distribution function near the Mott-Hubbard
transition in the one-dimensional t1-t2 Hubbard model (the zig-zag Hubbard
chain), with the density-matrix renormalization-group technique. We show that
for strong interactions the Mott-Hubbard transition occurs between the
metallic-phase and an insulating dimerized phase with incommensurate spin
excitations, suggesting a decoupling of magnetic and charge excitations not
present in weak coupling. We illustrate the signatures for the Mott-Hubbard
transition and the commensurate-incommensurate transition in the insulating
spin-gapped state in their respective ground-state momentum distribution
functions
BioPhysConnectoR: Connecting Sequence Information and Biophysical Models
<p>Abstract</p> <p>Background</p> <p>One of the most challenging aspects of biomolecular systems is the understanding of the coevolution in and among the molecule(s).</p> <p>A complete, theoretical picture of the selective advantage, and thus a functional annotation, of (co-)mutations is still lacking. Using sequence-based and information theoretical inspired methods we can identify coevolving residues in proteins without understanding the underlying biophysical properties giving rise to such coevolutionary dynamics. Detailed (atomistic) simulations are prohibitively expensive. At the same time reduced molecular models are an efficient way to determine the reduced dynamics around the native state. The combination of sequence based approaches with such reduced models is therefore a promising approach to annotate evolutionary sequence changes.</p> <p>Results</p> <p>With the <monospace>R</monospace> package <monospace>BioPhysConnectoR</monospace> we provide a framework to connect the information theoretical domain of biomolecular sequences to biophysical properties of the encoded molecules - derived from reduced molecular models. To this end we have integrated several fragmented ideas into one single package ready to be used in connection with additional statistical routines in <monospace>R</monospace>. Additionally, the package leverages the power of modern multi-core architectures to reduce turn-around times in evolutionary and biomolecular design studies. Our package is a first step to achieve the above mentioned annotation of coevolution by reduced dynamics around the native state of proteins.</p> <p>Conclusions</p> <p><monospace>BioPhysConnectoR</monospace> is implemented as an <monospace>R</monospace> package and distributed under GPL 2 license. It allows for efficient and perfectly parallelized functional annotation of coevolution found at the sequence level.</p
Correcting the Colour-Dipole Cascade Model with Fixed Order Matrix Elements
An algorithm is presented in which the Colour-Dipole Cascade Model as
implemented in the Ariadne program is corrected to match the fixed order
tree-level matrix elements for e+e- -> n jets. The result is a full parton
level generator for e+e- annihilation where the generated states are correct on
tree-level to fixed order in alpha_S and to all orders with modified leading
logarithmic (MLLA) accuracy. In this paper, matrix elements are used up to
second order in alpha_S, but the scheme is applicable also for higher orders.
An improvement to also include exact virtual corrections to fixed order is
suggested and the possibility to extend the scheme to hadronic collisions is
discussed
Solstice and Solar Position observations in Australian Aboriginal and Torres Strait Islander traditions
A major focus of the archaeoastronomical research conducted around the world
focuses on understanding how ancient cultures observed sunrise and sunset
points along the horizon, particularly at the solstices and equinoxes. Scholars
argue that observations of these solar points are useful for developing
calendars, informing ritual/ceremonial practices, and predicting seasonal
change. This is the foundation of the Eurocentric four-season Julian (and later
Gregorian) calendar. Famous examples include Stonehenge, Newgrange, Chichen
Itza, and Chankillo. Studies at these and other sites tend to focus on solar
point observations through alignments in stone arrangements, and the
orientations of monuments. Despite the ongoing study of Indigenous Knowledge in
Australia revealing a wealth of information about Aboriginal and Torres Strait
Islander observations and interpretations of solar, lunar, and stellar
properties and motions, very little has been published about the importance and
use of solar point observations. The authors examine this topic through four
case studies, based on methodological frameworks and approaches in ethnography,
ethnohistory, archaeology, and statistics. Our findings show that Aboriginal
and Torres Strait Islander people observe the solstices and other significant
sunrise/sunset points along the horizon for timekeeping and indicating seasonal
change - but in ways that are rather different to the four-season model
developed in Western Europe.Comment: Journal of Astronomical History and Heritage, Vol. 23(1), in press
(2020
Interaction induced collapse of a section of the Fermi sea in in the zig-zag Hubbard ladder
Using the next-nearest neighbor (zig-zag) Hubbard chain as an one
dimemensional model, we investigate the influence of interactions on the
position of the Fermi wavevectors with the density-matrix renormalization-group
technique (DMRG). For suitable choices of the hopping parameters we observe
that electron-electron correlations induce very different renormalizations for
the two different Fermi wavevectors, which ultimately lead to a complete
destruction of one section of the Fermi sea in a quantum critical point
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