1,589 research outputs found
Faunal remains associated with human cremations: The chalcolithic pits 16 and 40 from the Perdigões ditched enclosures (Reguengos de Monsaraz, Portugal)
Different funerary behaviors are recorded in the Iberian Peninsula during Late Prehistory. Cremation is not the most common practice and the association between human cremains and fauna is even scarcer. We present two Chalcolithic pits (pits 16 and 40) from the Perdigoes ditched enclosures, Reguengos de Monsaraz, Portugal. Humans were accompanied by animals and other votive materials such as arrowheads, ivory anthropomorphic figurines, and marble idols. Differences between the two contexts are discussed regarding the selection of faunal anatomical parts, the abundance of species, and the manipulation of remains. The results obtained were compared to previously published data from anthropological analysis. Burning damage intensity is different among pits and between humans and fauna. Hence, this suggests that the latter also resulted from diverse practices, including the possible selection of animal body portions for cremation and/or the deposition of selected burned bones or even related to patterns existing in the contexts of the provenance of the cremated materials before the cremation events.info:eu-repo/semantics/publishedVersio
O Fragmento, A Metade e O Todo : aproximação às deposições de cerâmica e fauna da Fossa 50 do recinto dos Perdigões (primeira metade do 3º milénio AC)
This paper presents the sequence of depositions inside Pit 50 of Perdigões ditched enclosure, dating from the first half of the 3rd millennium BC, and discusses the patterning that emerges from the detailed analysis of the distribution and levels of integrity of pottery and faunal remains along the infilling sequence. It is argued that these patterns are intentional and incorporate metaphorical meanings. Some interpretative hypothesis are put forward, taking in consideration the global scenario provided by Perdigões enclosure, from which this particular context recursively retrieves and provides significance.O Fragmento, A Metade e O Todo: aproximação às deposições de cerâmica e fauna da Fossa 50 do recinto dos Perdigões (primeira metade do 3º milénio AC).
Este artigo apresenta a sequência de deposições no interior da Fossa 50 do recinto de fossos dos Perdigões, datada da primeira metade do 3º milénio AC, e discute o padrão que emerge de uma análise detalhada da distribuição e níveis de integralidade da cerâmica e restos faunísticos ao longo da sequência. Algumas hipóteses interpretativas são avançadas, tendo em consideração o cenário global proporcionado pelos Perdigões, do qual este contexto específico recursivamente retira e providencia sentido.info:eu-repo/semantics/publishedVersio
Single-photon source based on FWM with adjustable linear SOP
We present a setup able to generate and detect single
photons in optical fibers using the stimulated four-wave
mixing (FWM) process. The results show an accurate generation
of single photons at four different linear states of polarization
(SOPs), with angles 0, 45, 90 and -45 degrees. The detection
was performed in back-to-back configuration and after
transmission over an optical fiber with a length up to 10 m
Fiber-optical communication system using polarization-encoding photons
We present a single-photon source based on the stimulated four-wave mixing process with
adjustable linear state of polarization. This source allowed us to generate non-orthogonal
states of polarization, that can be used for quantum key distribution experiments. The
average number of photon counts as a function of the angle of the analyzer was obtained
for two non-orthogonal linear states of polarization. The results show an accurate detection
after propagation through a standard single-mode optical fiber with a length equal to
20 km. We also employed a master/slave configuration between two avalanche photodiodes,
in order to check the probability of our single-photon source to emit pulses with
more than one photon, for an average number of photons per pulse, μ ∼ 0.2, and consequently
the probability of a photon to choose one of the paths. Results show that our
experimental scheme is suitable for polarization-encoding experiments.QuantTel - Quantum Secure TelecommunicationsQuantPrivTel - Quantum Private Telecommunications - PTDC/EEATEL/ 103402/200
Polarization-entangled photon pairs using spontaneous four-wave mixing in a fiber loop
We generate polarization-entangled photon pairs in the 1550-nm wavelength telecom band, using spontaneous fourwave mixing in a highly nonlinear fiber loop. With accidental coincidences subtracted, we obtain coincidence fringes with visibilities greater than 86%, and thus observe a violation of Clauser, Horne, Shimony and Holt (CHSH) inequality by 2.7 standard deviations. The experimental setup is built using only fiber connections, which contribute to its long time stability.QuantTel - Quantum Secure TelecommunicationsQuantPrivTel - Quantum Private Telecommunications - PTDC/EEATEL/ 103402/200
Time coincidence of entangled photon pairs using spontaneous four-wave mixing in a fiber loop
We obtained a source of entangled photon pairs in the 1550-nm wavelength band using spontaneous four-wave mixing (SpFWM) in a Sagnac fiber loop. Time coincidence of entangled photon pairs was verified for a 300-m dispersion-shifted fiber (DSF), using an avalanche photodiode (APD).QuantTel - Quantum Secure TelecommunicationsQuant- PrivTel - Quantum Private Telecommunications - PTDC/EEATEL/ 103402/200
Correlated photon-pair generation in a highly nonlinear fiber using spontaneous FWM
We generate 1550 nm correlated photon pairs through the spontaneous four-wave mixing (SpFWM) process in a highly nonlinear fiber (HNLF). The pair source quality generation is evaluated by the coincidence-to-accidental ratio (CAR) parameter. It is verified that the spontaneous Raman scattering (SpRS) photons generated inside the fiber contribute to the degradation of the source. Nevertheless, a CAR value of 2.77 is found for a pump power at the input of the fiber of 1.1 mW.QuantPrivTel- Quantum Private Telecommunications - PTDC/EEATEL/ 103402/2008
‘Animal Farm’
This paper presents the results of the excavations carried out in the Chalcolithic contexts from the walled enclosure of Ota (Alenquer, Portugal). Six new absolute dates allow the discussion of the stratigraphical evidence and chronologically frame the zooarchaeological and taphonomical analysis of the faunal assemblage. Domesticated swine, caprine and bovine are prevalent, while wild species, most notably leporids, but also red deer, auroch and wild boar, among others, are less common. Exploitation and management of animals for the acquisition of primary and secondary products are inferred. Existing data suggests that the economic intensification that started during the previous phases was ongoing
Replica Symmetry Breaking Instability in the 2D XY model in a random field
We study the 2D vortex-free XY model in a random field, a model for randomly
pinned flux lines in a plane. We construct controlled RG recursion relations
which allow for replica symmetry breaking (RSB). The fixed point previously
found by Cardy and Ostlund in the glass phase is {\it unstable} to RSB.
The susceptibility associated to infinitesimal RSB perturbation in the
high-temperature phase is found to diverge as
when . This provides analytical evidence that RSB occurs
in finite dimensional models. The physical consequences for the glass phase are
discussed.Comment: 8 pages, REVTeX, LPTENS-94/2
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