1,902 research outputs found
Experimental Realization of Optimal Noise Estimation for a General Pauli Channel
We present the experimental realization of the optimal estimation protocol
for a Pauli noisy channel. The method is based on the generation of 2-qubit
Bell states and the introduction of quantum noise in a controlled way on one of
the state subsystems. The efficiency of the optimal estimation, achieved by a
Bell measurement, is shown to outperform quantum process tomography
An analytical approximation scheme to two point boundary value problems of ordinary differential equations
A new (algebraic) approximation scheme to find {\sl global} solutions of two
point boundary value problems of ordinary differential equations (ODE's) is
presented. The method is applicable for both linear and nonlinear (coupled)
ODE's whose solutions are analytic near one of the boundary points. It is based
on replacing the original ODE's by a sequence of auxiliary first order
polynomial ODE's with constant coefficients. The coefficients in the auxiliary
ODE's are uniquely determined from the local behaviour of the solution in the
neighbourhood of one of the boundary points. To obtain the parameters of the
global (connecting) solutions analytic at one of the boundary points, reduces
to find the appropriate zeros of algebraic equations. The power of the method
is illustrated by computing the approximate values of the ``connecting
parameters'' for a number of nonlinear ODE's arising in various problems in
field theory. We treat in particular the static and rotationally symmetric
global vortex, the skyrmion, the Nielsen-Olesen vortex, as well as the 't
Hooft-Polyakov magnetic monopole. The total energy of the skyrmion and of the
monopole is also computed by the new method. We also consider some ODE's coming
from the exact renormalization group. The ground state energy level of the
anharmonic oscillator is also computed for arbitrary coupling strengths with
good precision.Comment: 5 pages, 3 tables, Late
Dynamics of Saccharomyces cerevisiae strains isolated from vine bark in vineyard: Influence of plant age and strain presence during grape must spontaneous fermentations
In this study, two vineyards of different age were chosen. During three years, a sampling campaign was performed for isolating vineyard-associated Saccharomyces cerevisiae (S. cerevisiae) strains. Bark portions and, when present, grape bunches were regularly collected from the same vine plants during the overall sampling period. Each bark portion was added to a synthetic must, while each grape bunch was manually crushed, and fermentations were run to isolate S. cerevisiae strains. All collected yeasts were identified at different species and strain levels to evaluate the genetic variability of S. cerevisiae strains in the two vineyards and strains dynamics. Moreover, bark-associated strains were compared with those isolated from spontaneous fermentations of grapes collected during the two harvests. Regarding the youngest vineyard, no S. cerevisiae was identified on bark and grape surface, highlighting the importance of vine age on yeast colonization. Results reported the isolation of S. cerevisiae from vine bark of the old vineyard at all sampling times, regardless of the presence of the grape bunch. Therefore, this environment can be considered an alternative ecological niche that permanently hosts S. cerevisiae. Bark-associated strains were not found on grape bunches and during pilot-scale vinifications, indicating no significative strain transfer from vine bark to the grape must. Commercial starters were identified as well both in vineyards and during vinifications
Variational approach to a class of nonlinear oscillators with several limit cycles
We study limit cycles of nonlinear oscillators described by the equation
. Depending on the nonlinearity this equation
may exhibit different number of limit cycles.
We show that limit cycles correspond to relative extrema of a certain
functional. Analytical results in the limits and are
in agreement with previously known criteria. For intermediate numerical
determination of the limit cycles can be obtained.Comment: 12 pages, 3 figure
Black hole entropy from classical Liouville theory
In this article we compute the black hole entropy by finding a classical
central charge of the Virasoro algebra of a Liouville theory using the Cardy
formula. This is done by performing a dimensional reduction of the Einstein
Hilbert action with the ansatz of spherical symmetry and writing the metric in
conformally flat form. We obtain two coupled field equations. Using the near
horizon approximation the field equation for the conformal factor decouples.
The one concerning the conformal factor is a Liouville equation, it posses the
symmetry induced by a Virasoro algebra. We argue that it describes the
microstates of the black hole, namely the generators of this symmetry do not
change the thermodynamical properties of the black hole.Comment: LaTeX, 11 pages, to appear on JHE
Histomorphometric analysis of osteocyte lacunae in human and pig: exploring its potential for species discrimination
In recent years, several studies have focused on species discrimination of bone fragments by histological analysis. According to literature, the most consistent distinguishing features are Haversian canal and Haversian system areas. Nonetheless, there is a consistent overlap between human and non-human secondary osteon dimensions. One of the features that have never been analyzed for the purpose of species discrimination is the osteocyte lacuna, a small oblong cavity in which the osteocyte is locked in. The aim of this study is to verify whether there are significant quantitative differences between human and pig lacunae within secondary osteons with similar areas. Study sample comprises the midshaft of long bones (humerus, radius, ulna, femur, tibia, and fibula) of a medieval human adult and a juvenile pig. Sixty-eight secondary osteons with similar areas have been selected for each species and a total of 1224 osteocyte lacunae have been measured. For each osteon, the total number of lacunae was counted, and the following measurements were taken: minimum and maximum diameter, area, perimeter, and circularity of nine lacunae divided between inner, intermediate, and outer lacunae. Statistical analysis showed minimal differences between human and pig in the number of lacunae per osteons and in the minimum diameter (P > 0.05). On the contrary, a significant difference (P < 0.001) has been observed in the maximum diameter, perimeter, area, and circularity. Although there is the need for further research on different species and larger sample, these results highlighted the potential for the use of osteocyte lacunae as an additional parameter for species discrimination. Concerning the difference between the dimensions of osteocyte lacunae based on their position within the osteon (inner, intermediate, and outer lacunae), results showed that their size decreases from the cement line towards the Haversian canal both in human and pig
Convergence of nonlocal threshold dynamics approximations to front propagation
In this note we prove that appropriately scaled threshold dynamics-type
algorithms corresponding to the fractional Laplacian of order converge to moving fronts. When the resulting interface
moves by weighted mean curvature, while for the normal velocity is
nonlocal of ``fractional-type.'' The results easily extend to general nonlocal
anisotropic threshold dynamics schemes.Comment: 19 page
An Interoperable Electronic Health Record System for Clinical Cardiology
Currently in hospitals, there are several separate information systems that manage, very often autonomously, the patient’s personal, clinical and diagnostic data. An electronic health record system has been specifically developed for a cardiology ward and it has been designed “ab initio” to be fully integrated into the hospital information system and to exchange data with the regional health information infrastructure. All documents have been given as Health Level 7 (HL7) clinical document architecture and messages are sent as HL7-Version 2 (V2) and/or HL7 Fast Healthcare Interoperability Resources (FHIR). Specific decision support sections for specific aspects have also been included. The system has been used for more than three years with a good level of satisfaction by the users. In the future, the system can be the basis for secondary use for clinical studies, further decision support systems and clinical trials
Efeito da combinação de calcário de xisto e calcário dolomítico sobre a produtividade de grãos de dois sistemas de rotação de culturas.
Some results on homoclinic and heteroclinic connections in planar systems
Consider a family of planar systems depending on two parameters and
having at most one limit cycle. Assume that the limit cycle disappears at some
homoclinic (or heteroclinic) connection when We present a method
that allows to obtain a sequence of explicit algebraic lower and upper bounds
for the bifurcation set The method is applied to two quadratic
families, one of them is the well-known Bogdanov-Takens system. One of the
results that we obtain for this system is the bifurcation curve for small
values of , given by . We obtain
the new three terms from purely algebraic calculations, without evaluating
Melnikov functions
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