15,331 research outputs found
Error Propagation in the Hypercycle
We study analytically the steady-state regime of a network of n error-prone
self-replicating templates forming an asymmetric hypercycle and its error tail.
We show that the existence of a master template with a higher non-catalyzed
self-replicative productivity, a, than the error tail ensures the stability of
chains in which m<n-1 templates coexist with the master species. The stability
of these chains against the error tail is guaranteed for catalytic coupling
strengths (K) of order of a. We find that the hypercycle becomes more stable
than the chains only for K of order of a2. Furthermore, we show that the
minimal replication accuracy per template needed to maintain the hypercycle,
the so-called error threshold, vanishes like sqrt(n/K) for large K and n<=4
Redundancy of stereoscopic images: Experimental Evaluation
With the recent advancement in visualization devices over the last years, we
are seeing a growing market for stereoscopic content. In order to convey 3D
content by means of stereoscopic displays, one needs to transmit and display at
least 2 points of view of the video content. This has profound implications on
the resources required to transmit the content, as well as demands on the
complexity of the visualization system. It is known that stereoscopic images
are redundant, which may prove useful for compression and may have positive
effect on the construction of the visualization device. In this paper we
describe an experimental evaluation of data redundancy in color stereoscopic
images. In the experiments with computer generated and real life and test
stereo images, several observers visually tested the stereopsis threshold and
accuracy of parallax measuring in anaglyphs and stereograms as functions of the
blur degree of one of two stereo images and color saturation threshold in one
of two stereo images for which full color 3D perception with no visible color
degradations is maintained. The experiments support a theoretical estimate that
one has to add, to data required to reproduce one of two stereoscopic images,
only several percents of that amount of data in order to achieve stereoscopic
perception
The current status of dental education and the dental profession in Chile
Indexación: Scopus.Objective: To describe the current situation of the dental profession in Chile, including training and workforce issues. Material and Methods: Data were collected from different national institutions, which included information regarding number of current registered dentists, university of graduation, geographical distribution, professional position, additional specialty certifications obtained, the number and characteristics of dental surgeons who work in the public and private sectors, the traditional character of the university, the accreditation status of the undergraduate dental programs and the general population number. Results: Currently there are 32 schools of Dentistry in Chile, of which 21 have their quality certified. There are 19,100 Chilean dentists and 1,727 foreign dentists registered. The number of graduates from private universities has increased significantly. Currently, 2,164 dentists work for MINSAL. Less than a third hold a specialty certification. Forty-five percent of the dental specialists obtained their certification from universities. The current professional ratio is 104 dentists per 100,000 habitants. Conclusion: The number of dentists in Chile has increased progressively during the last years, mainly associated with the opening of new dental schools. Only 28% of the Chilean dental schools have certified their quality for the total duration of the undergraduate program. Regarding the workforce, there is a public/private and geographical inequities in dentists’ distribution.http://revista.uepb.edu.br/index.php/pboci/article/view/3875/pd
Raman-scattering study of the phonon dispersion in twisted bi-layer graphene
Bi-layer graphene with a twist angle \theta\ between the layers generates a
superlattice structure known as Moir\'{e} pattern. This superlattice provides a
\theta-dependent q wavevector that activates phonons in the interior of the
Brillouin zone. Here we show that this superlattice-induced Raman scattering
can be used to probe the phonon dispersion in twisted bi-layer graphene (tBLG).
The effect reported here is different from the broadly studied double-resonance
in graphene-related materials in many aspects, and despite the absence of
stacking order in tBLG, layer breathing vibrations (namely ZO' phonons) are
observed.Comment: 18 pages, 4 figures, research articl
Finding the Higgs Boson through Supersymmetry
The study of displaced vertices containing two b--jets may provide a double
discovery at the Large Hadron Collider (LHC): we show how it may not only
reveal evidence for supersymmetry, but also provide a way to uncover the Higgs
boson necessary in the formulation of the electroweak theory in a large region
of the parameter space. We quantify this explicitly using the simplest minimal
supergravity model with bilinear breaking of R-parity, which accounts for the
observed pattern of neutrino masses and mixings seen in neutrino oscillation
experiments.Comment: 7 pages, 7 figures. Final version to appear at PRD. Discussion and
results were enlarge
Phenomenological Analysis of and Elastic Scattering Data in the Impact Parameter Space
We use an almost model-independent analytical parameterization for and
elastic scattering data to analyze the eikonal, profile, and
inelastic overlap functions in the impact parameter space. Error propagation in
the fit parameters allows estimations of uncertainty regions, improving the
geometrical description of the hadron-hadron interaction. Several predictions
are shown and, in particular, the prediction for inelastic overlap
function at TeV shows the saturation of the Froissart-Martin
bound at LHC energies.Comment: 15 pages, 16 figure
Ultrahigh Transmission Optical Nanofibers
We present a procedure for reproducibly fabricating ultrahigh transmission
optical nanofibers (530 nm diameter and 84 mm stretch) with single-mode
transmissions of 99.95 0.02%, which represents a loss from tapering of
2.6 10 dB/mm when normalized to the entire stretch. When
controllably launching the next family of higher-order modes on a fiber with
195 mm stretch, we achieve a transmission of 97.8 2.8%, which has a loss
from tapering of 5.0 10 dB/mm when normalized to the
entire stretch. Our pulling and transfer procedures allow us to fabricate
optical nanofibers that transmit more than 400 mW in high vacuum conditions.
These results, published as parameters in our previous work, present an
improvement of two orders of magnitude less loss for the fundamental mode and
an increase in transmission of more than 300% for higher-order modes, when
following the protocols detailed in this paper. We extract from the
transmission during the pull, the only reported spectrogram of a fundamental
mode launch that does not include excitation to asymmetric modes; in stark
contrast to a pull in which our cleaning protocol is not followed. These
results depend critically on the pre-pull cleanliness and when properly
following our pulling protocols are in excellent agreement with simulations.Comment: 32 pages, 10 figures, accepted to AIP Advance
Dynamics of active membranes with internal noise
We study the time-dependent height fluctuations of an active membrane
containing energy-dissipating pumps that drive the membrane out of equilibrium.
Unlike previous investigations based on models that neglect either curvature
couplings or random fluctuations in pump activities, our formulation explores
two new models that take both of these effects into account. In the first
model, the magnitude of the nonequilibrium forces generated by the pumps is
allowed to fluctuate temporally. In the second model, the pumps are allowed to
switch between "on" and "off" states. We compute the mean squared displacement
of a membrane point for both models, and show that they exhibit distinct
dynamical behaviors from previous models, and in particular, a superdiffusive
regime specifically arising from the shot noise.Comment: 7 pages, 4 figure
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