225 research outputs found
Field Notes from the Odyssey: The Fabulous Ethnography of Aiolie, Aiaie, and Ogygie
Odysseus’ ethnographic digressions in books 9-12 of the Odyssey—the so-called Apologue—have served as the premier paradigm for mythic and actual ethnography from Herodotus through Marco Polo and Christopher Columbus, and more particularly, for the ‘I-witnessing approach’ of ethnography. Among the peoples and lands and styles of thinking he encountered (Odyssey 1.3), the hero also became acquainted with several islands. As microcosms of larger societies, islands furnish ‘master metaphors’ and models with which to think about culture. In this article I discuss three islands from the Apologue in the chronological order of Odysseus’ travels. They are inseparable from their geography and the personality and ‘life style’ of their inhabitants, as will be seen; these islands adumbrate the moral and gendered mythic cartography of Archaic Greece.Odysseus’ ethnographic digressions in books 9-12 of the Odyssey—the so-called Apologue—have served as the premier paradigm for mythic and actual ethnography from Herodotus through Marco Polo and Christopher Columbus, and more particularly, for the ‘I-witnessing approach’ of ethnography. Among the peoples and lands and styles of thinking he encountered (Odyssey 1.3), the hero also became acquainted with several islands. As microcosms of larger societies, islands furnish ‘master metaphors’ and models with which to think about culture. In this article I discuss three islands from the Apologue in the chronological order of Odysseus’ travels. They are inseparable from their geography and the personality and ‘life style’ of their inhabitants, as will be seen; these islands adumbrate the moral and gendered mythic cartography of Archaic Greece.Odysseus’ ethnographic digressions in books 9-12 of the Odyssey—the so-called Apologue—have served as the premier paradigm for mythic and actual ethnography from Herodotus through Marco Polo and Christopher Columbus, and more particularly, for the ‘I-witnessing approach’ of ethnography. Among the peoples and lands and styles of thinking he encountered (Odyssey 1.3), the hero also became acquainted with several islands. As microcosms of larger societies, islands furnish ‘master metaphors’ and models with which to think about culture. In this article I discuss three islands from the Apologue in the chronological order of Odysseus’ travels. They are inseparable from their geography and the personality and ‘life style’ of their inhabitants, as will be seen; these islands adumbrate the moral and gendered mythic cartography of Archaic Greece
Geometric flows in Horava-Lifshitz gravity
We consider instanton solutions of Euclidean Horava-Lifshitz gravity in four
dimensions satisfying the detailed balance condition. They are described by
geometric flows in three dimensions driven by certain combinations of the
Cotton and Ricci tensors as well as the cosmological-constant term. The
deformation curvature terms can have competing behavior leading to a variety of
fixed points. The instantons interpolate between any two fixed points, which
are vacua of topologically massive gravity with Lambda > 0, and their action is
finite. Special emphasis is placed on configurations with SU(2) isometry
associated with homogeneous but generally non-isotropic Bianchi IX model
geometries. In this case, the combined Ricci-Cotton flow reduces to an
autonomous system of ordinary differential equations whose properties are
studied in detail for different couplings. The occurrence and stability of
isotropic and anisotropic fixed points are investigated analytically and some
exact solutions are obtained. The corresponding instantons are classified and
they are all globally R x S^3 and complete spaces. Generalizations to
higher-dimensional gravities are also briefly discussed.Comment: 67 pages, 16 figures; more solutions found, 1 extra figure, 1 more
reference added in v2; minor typos corrected in v3 (to appear in JHEP); an
acknowledgement added in v
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Development of an antenna system for a relay-based wireless network. Simulation and measurement of antenna systems for relay-based wireless network, covering the backhaul and access links and applying beam forming technology.
The proliferation of modern wireless networks increases demand for high capacity and
throughput in order to provide faster, more robust, efficient and broadband services to end users.
Mobile WiMAX and LTE are examples of such networks in which for some cases they have
exposed limited connectivity due to harsh environment. Relay stations are preferred to
overcome problems of weak or no access for such network devices, that are placed in specific
positions to maintain high quality of data transfer at low cost and provide the required
connectivity anywhere anytime. These stations should be equipped with an antenna system
capable of establishing communication between base station (backhaul link) and end users
(access link).
This thesis focuses on the design and development of a new antenna system that is suitable for a
relay-based wireless network. Planar geometries of microstrip patch antennas are utilized. The
antenna system comprises two antenna modules: a new design of a single antenna for access
link and a new design of an antenna array for backhaul link realization. Both antenna
specifications are compatible with the IEEE802.16j protocol standard. Hence, relay station
should be capable of pointing its radiation pattern to the base station antenna, thus to achieve the
desired radiation pattern of the relay station, a new beam-forming module is proposed, designed
and developed to generate the proper radiation pattern. The beam-forming module incorporating
digital phase shifters and attenuator chips is fabricated and tested. The optimization process
using the Least Mean Square (LMS) algorithm is considered in this study to assign the proper
phase and amplitude that is necessary to each radiation element excitation current, to produce
the desired steered radiation pattern.
A comprehensive study on the coupling effects for several relative positions between two new
backhaul and access link antenna elements is performed. Two new antenna configurations for
coupling reduction are tested and the simulated and measured results in terms of antenna
radiation performances were compared and commented
Combined use of weather forecasting and satellite remote sensing information for fire risk, fire and fire impact monitoring
The restoration of fire-affected forest areas needs to be combined with their future protection from renewed catastrophic fires, such as those that occurred in Greece during the 2007 summer season. The present work demonstrates that the use of various sources of satellite data in conjunction with weather forecast information is capable of providing valuable information for the characterization of fire danger with the purpose of protecting the Greek national forest areas. This study shows that favourable meteorological conditions have contributed to the fire outbreak during the days of the unusually damaging fires in Peloponnese as well as Euboia (modern Greek: Evia) at the end of August 2007. During those days, Greece was located between an extended high pressure system in Central Europe and a low pressure system in the Middle East. Their combination resulted in strong north-northeasterly winds in the Aegean Sea. As a consequence, strong winds were also observed in the regions of Evia and Peloponnese, especially in mountainous areas. The analysis of satellite images showing smoke emitted from the fires corroborates the results from the weather forecasts. A further analysis using the Fraction of Absorbed Photosyntetically Active Radiation (FAPAR) as an indicator of active vegetation shows the extent of the destruction caused by the fire. The position of the burned areas coincides with that of the active fires detected in the earlier satellite image. Using the annual maximum FAPAR as an indicator of regional vegetation density, it was found that only regions with relatively high FAPAR were burned
Ricci flows and expansion in axion-dilaton cosmology
We study renormalization-group flows by deforming a class of conformal
sigma-models. We consider overall scale factor perturbation of Einstein spaces
as well as more general anisotropic deformations of three-spheres. At leading
order in alpha, renormalization-group equations turn out to be Ricci flows. In
the three-sphere background, the latter is the Halphen system, which is exactly
solvable in terms of modular forms. We also analyze time-dependent deformations
of these systems supplemented with an extra time coordinate and time-dependent
dilaton. In some regimes time evolution is identified with
renormalization-group flow and time coordinate can appear as Liouville field.
The resulting space-time interpretation is that of a homogeneous isotropic
Friedmann-Robertson-Walker universe in axion-dilaton cosmology. We find as
general behaviour the superposition of a big-bang (polynomial) expansion with a
finite number of oscillations at early times. Any initial anisotropy disappears
during the evolution.Comment: 22 page
Coupling Measurements of an Antenna System Suitable for Relay-Aided WiMAX Network
YesIn this paper two novel antennas, suitable for access and backhaul links, are designed, fabricated and tested for a Relay Station in a WiMAX wireless network. A single modi¯ed E-shaped patch antenna is described, presenting 10 dB gain over 12.4% bandwidth. This antenna element is used for the design of a 4 £ 4 planar array which provides experimental gain of 21.2 dB. The antenna system on the Relay Station operates at 3.4 GHz and includes one single antenna element for access link realization and an antenna array for the backhaul link realization. These antennas are installed in two con¯guration arrangements and tested in terms of their radiation performances and coupling e®ects. The simulated and measured results are quite satisfactory and in good agreement at which the maximum coupling between the access and backhaul antennas is found below ¡25 dB for all tested cases
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