4,254 research outputs found
Improved Contrast Sensitivity DVS and its Application to Event-Driven Stereo Vision
This paper presents a new DVS sensor with
one order of magnitude improved contrast sensitivity over
previous reported DVSs. This sensor has been applied to a
bio-inspired event-based binocular system that performs
3D event-driven reconstruction of a scene. Events from two
DVS sensors are matched by using precise timing
information of their ocurrence. To improve matching
reliability, satisfaction of epipolar geometry constraint is
required, and simultaneously available information on the
orientation is used as an additional matching constraint.Ministerio de Economía y Competitividad PRI-PIMCHI-2011-0768Ministerio de Economía y Competitividad TEC2009-10639-C04-01Junta de Andalucía TIC-609
Hierarchy of inequalities for quantitative duality
We derive different relations quantifying duality in a generic two-way
interferometer. These relations set different upper bounds to the visibility V
of the fringes measured at the output port of the interferometer. A hierarchy
of inequalities is presented which exhibits the influence of the availability
to the experimenter of different sources of which-way information contributing
to the total distinguishability D of the ways. For mixed states and unbalanced
interferometers an inequality is derived, V^2+ Xi^2 \leq 1, which can be more
stringent than the one associated with the distinguishability (V^2+ D^2 \leq
1).Comment: 7 pages, 4 figure
Nietzsche i l'escepticisme : assaig d'aclariment d'una pretesa contradicció
S'ha afirmat sovint que en matèria de teoria del coneixement, Nietzsche és un escèptic. En aquest article es fa un acurat repàs de l'obra nietzscheana a la cerca de les sentències en pro o en contra de l'escepticisme, on les posicions en contra d'aquest són especialment abundoses en contradicció amb aquelles interpretacions. En el curs d'aquest recorregut s'esbossa el concepte nietzscheà de filosofia i la diferència entre aquesta i la ciència. La tesi final és que Nietzsche considera l'escepticisme una condició necessària, però no suficient, de la vertadera filosofia, la filosofia sobirana i disciplinadora de la cultura. Així es dissoldrà la contradicció entre les interpretacions de l'autor com un escèptic i les que el consideren un antiescèptic.It has often been said that on the subject of the theory of knowledge Nietzsche was a sceptic. This article provides a careful review of Nietzsche's work, a search for statements both for and against scepticism which finds abundant evidence of a stance against it wich would thus conrradict this frequent interpretation. Nictzschean philosophy is outlined in the course of the paper and the differcnce between it and science is established. The final thesis is that Nietzsche considered scepticism to he a necessary but insufficient condition of true philosophy, the supremme and disciplinary philosophy of culture. Thus the contradiction between interpretations of the author as a sceptic or as an anti-sceptic will be dispelled
Live Demonstration: Multiplexing AER Asynchronous Channels over LVDS Links with Flow-Control and Clock- Correction for Scalable Neuromorphic Systems
In this live demonstration we exploit the use of a
serial link for fast asynchronous communication in massively
parallel processing platforms connected to a DVS for realtime
implementation of bio-inspired vision processing on
spiking neural networks
Coupling Between Thermal Oscillations in the Surface of a Micro-Cylinder and Vortex Shedding
his article studies the coupling between prescribed thermal oscillations in the surface of a micro-cylinder and vortex shedding. We deal with the unsteady, laminar, compressible flow regime where the aerodynamics forces have a periodic behavior. It is shown that appropriate spatial and time-dependent temperature oscillations on the surface of the micro-cylinder create a resonance that controls the amplitude and frequency of both lift and drag coefficients. In practice, what we study is a mechanism to modulate the amplitude and frequency of mechanical loads of aerodynamics origin in a micro-structure by using surface temperature fluctuations as the control parameter
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Past and present potential distribution of the Iberian Abies species: A phytogeographic approach using pollen data and species distribution models
This is the accepted version of the following article: Alba-Sánchez, F., López-Sáez, J. A., Pando, B. B.-d., Linares, J. C., Nieto-Lugilde, D. and López-Merino, L. (2010), Past and present potential distribution of the Iberian Abies species: a phytogeographic approach using fossil pollen data and species distribution models. Diversity and Distributions, 16: 214–228, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/j.1472-4642.2010.00636.x/abstract.Aim - Quaternary palaeopalynological records collected throughout the Iberian Peninsula and species distribution models (SDMs) were integrated to gain a better understanding of the historical biogeography of the Iberian Abies species (i.e. Abies pinsapo and Abies alba). We hypothesize that SDMs and Abies palaeorecords are closely correlated, assuming a certain stasis in climatic and topographic ecological niche dimensions. In addition, the modelling results were used to assign the fossil records to A. alba or A. pinsapo, to identify environmental variables affecting their distribution, and to evaluate the ecological segregation between the two taxa.
Location - The Iberian Peninsula.
Methods - For the estimation of past Abies distributions, a hindcasting process was used. Abies pinsapo and A. alba were modelled individually, first calibrating the model for their current distributions in relation to the present climate, and then projecting it into the past—the last glacial maximum (LGM) and the Middle Holocene periods—in relation to palaeoclimate simulations. The resulting models were compared with Iberian-wide fossil pollen records to detect areas of overlap.
Results - The overlap observed between past Abies refugia—inferred from fossil pollen records—and the SDMs helped to construct the Quaternary distribution of the Iberian Abies species. SDMs yielded two well-differentiated potential distributions: A. pinsapo throughout the Baetic mountain Range and A. alba along the Pyrenees and Cantabrian Range. These results propose that the two taxa remained isolated throughout the Quaternary, indicating a significant geographical and ecological segregation. In addition, no significant differences were detected comparing the three projections (present-day, Mid-Holocene and LGM), suggesting a relative climate stasis in the refuge areas during the Quaternary.
Main conclusions - Our results confirm that SDM projections can provide a useful complement to palaeoecological studies, offering a less subjective and spatially explicit hypothesis concerning past geographic patterns of Iberian Abies species. The integration of ecological-niche characteristics from known occurrences of Abies species in conjunction with palaeoecological studies could constitute a suitable tool to define appropriate areas in which to focus proactive conservation strategies.The Andalusian Innovation,
Science, and Industry Regional Ministry and the National Plan of the Spanish Government
Experimental violation of a spin-1 Bell inequality using maximally-entangled four-photon states
We demonstrate the first experimental violation of a spin-1 Bell inequality.
The spin-1 inequality is a calculation based on the Clauser, Horne, Shimony and
Holt formalism. For entangled spin-1 particles the maximum quantum mechanical
prediction is 2.552 as opposed to a maximum of 2, predicted using local hidden
variables. We obtained an experimental value of 2.27 using the
four-photon state generated by pulsed, type-II, stimulated parametric
down-conversion. This is a violation of the spin-1 Bell inequality by more than
13 standard deviations.Comment: 5 pages, 3 figures, Revtex4. Problem with figures resolve
Quality of a Which-Way Detector
We introduce a measure Q of the "quality" of a quantum which-way detector,
which characterizes its intrinsic ability to extract which-way information in
an asymmetric two-way interferometer. The "quality" Q allows one to separate
the contribution to the distinguishability of the ways arising from the quantum
properties of the detector from the contribution stemming from a-priori
which-way knowledge available to the experimenter, which can be quantified by a
predictability parameter P. We provide an inequality relating these two sources
of which-way information to the value of the fringe visibility displayed by the
interferometer. We show that this inequality is an expression of duality,
allowing one to trace the loss of coherence to the two reservoirs of which-way
information represented by Q and P. Finally, we illustrate the formalism with
the use of a quantum logic gate: the Symmetric Quanton-Detecton System (SQDS).
The SQDS can be regarded as two qubits trying to acquire which way information
about each other. The SQDS will provide an illustrating example of the
reciprocal effects induced by duality between system and which-way detector.Comment: 10 pages, 5 figure
Brane world corrections to scalar vacuum force in RSII-p
Vacuum force is an interesting low energy test for brane worlds due to its
dependence on field's modes and its role in submillimeter gravity experiments.
In this work we generalize a previous model example: the scalar field vacuum
force between two parallel plates lying in the brane of a Randall-Sundrum
scenario extended by compact dimensions (RSII-). Upon use of Green's
function technique, for the massless scalar field, the 4D force is obtained
from a zero mode while corrections turn out attractive and depend on the
separation between plates as . For the massive scalar field a
quasilocalized mode yields the 4D force with attractive corrections behaving
like . Corrections are negligible w.r.t. 4D force for
radius less than m. Although the case is not
physically viable due to the different behavior in regard to localization for
the massless scalar and electromagnetic fields it yields an useful comparison
between the dimensional regularization and Green's function techniques as we
describe in the discussion.Comment: 14 pages, v2: discussion clarified, reference adde
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