12,705 research outputs found
Entanglement production by quantum error correction in the presence of correlated environment
We analyze the effect of a quantum error correcting code on the entanglement
of encoded logical qubits in the presence of a dephasing interaction with a
correlated environment. Such correlated reservoir introduces entanglement
between physical qubits. We show that for short times the quantum error
correction interprets such entanglement as errors and suppresses it. However
for longer time, although quantum error correction is no longer able to correct
errors, it enhances the rate of entanglement production due to the interaction
with the environment.Comment: 7 pages, 3 figures, published versio
The squashed entanglement of the noiseless quantum Gaussian attenuator and amplifier
We determine the maximum squashed entanglement achievable between sender and
receiver of the noiseless quantum Gaussian attenuators and amplifiers and we
prove that it is achieved sending half of an infinitely squeezed two-mode
vacuum state. The key ingredient of the proof is a lower bound to the squashed
entanglement of the quantum Gaussian states obtained applying a two-mode
squeezing operation to a quantum thermal Gaussian state tensored with the
vacuum state. This is the first lower bound to the squashed entanglement of a
quantum Gaussian state and opens the way to determine the squashed entanglement
of all quantum Gaussian channels. Moreover, we determine the classical squashed
entanglement of the quantum Gaussian states above and show that it is strictly
larger than their squashed entanglement. This is the first time that the
classical squashed entanglement of a mixed quantum Gaussian state is
determined
Collective Decoherence of Nuclear Spin Clusters
The problem of dipole-dipole decoherence of nuclear spins is considered for
strongly entangled spin cluster. Our results show that its dynamics can be
described as the decoherence due to interaction with a composite bath
consisting of fully correlated and uncorrelated parts. The correlated term
causes the slower decay of coherence at larger times. The decoherence rate
scales up as a square root of the number of spins giving the linear scaling of
the resulting error. Our theory is consistent with recent experiment reported
in decoherence of correlated spin clusters.Comment: 4 pages, 4 figure
Cloning transformations in spin networks without external control
In this paper we present an approach to quantum cloning with unmodulated spin
networks. The cloner is realized by a proper design of the network and a choice
of the coupling between the qubits. We show that in the case of phase covariant
cloner the XY coupling gives the best results. In the 1->2 cloning we find that
the value for the fidelity of the optimal cloner is achieved, and values
comparable to the optimal ones in the general N->M case can be attained. If a
suitable set of network symmetries are satisfied, the output fidelity of the
clones does not depend on the specific choice of the graph. We show that spin
network cloning is robust against the presence of static imperfections.
Moreover, in the presence of noise, it outperforms the conventional approach.
In this case the fidelity exceeds the corresponding value obtained by quantum
gates even for a very small amount of noise. Furthermore we show how to use
this method to clone qutrits and qudits. By means of the Heisenberg coupling it
is also possible to implement the universal cloner although in this case the
fidelity is 10% off that of the optimal cloner.Comment: 12 pages, 13 figures, published versio
QuEChERS-based analytical methods developed for LC-MS/MS multiresidue determination of pesticides in representative crop fatty matrices: Olives and sunflower seeds
Oilseed crops are greatly extended all over the world. Their high fat content can interfere during pesticide
multiresidue analysis through liquid chromatography-tandem mass spectrometry (LC-MS/MS). This work aimed
at overcoming this issue by developing and validating two QuEChERS-based methods for LC-MS/MS determination of 42 pesticides in two fatty food matrices: olives and sunflower seeds. Optimization of the extraction method was achieved following a 26-2 fractional factorial design in a highly cost-effective way. Validation of the multi-residue methods demonstrated improved limits of detection, below the established maximum residue levels (MRLs) for almost all compounds, good precision, and trueness, in compliance with SANTE guidelines.
Application of these methods to the analysis of real samples from the Iberian Peninsula showed the presence of some pesticides of relevant environmental concern, including four compounds contained in the Pesticide Action Network International list of highly hazardous pesticides, found at levels between 0.03 ng/g and 104 ng/g
Measurements and tests on FBK silicon sensors with an optimized electronic design for a CTA camera
In October 2013, the Italian Ministry approved the funding of a Research &
Development (R&D) study, within the "Progetto Premiale TElescopi CHErenkov made
in Italy (TECHE)", devoted to the development of a demonstrator for a camera
for the Cherenkov Telescope Array (CTA) consortium. The demonstrator consists
of a sensor plane based on the Silicon Photomultiplier (SiPM) technology and on
an electronics designed for signal sampling. Preliminary tests on a matrix of
sensors produced by the Fondazione Bruno Kessler (FBK-Trento, Italy) and on
electronic prototypes produced by SITAEL S.p.A. will be presented. In
particular, we used different designs of the electronics in order to optimize
the output signals in terms of tail cancellation. This is crucial for
applications where a high background is expected, as for the CTA experiment.Comment: 5 pages, 6 figures; Proceedings of the 10th Workshop on Science with
the New Generation of High-Energy Gamma-ray experiments (SciNeGHE) -
PoS(Scineghe2014)00
Persistent organochlorine compounds in fetal and maternal tissues: evaluation of their potential influence on several indicators of fetal growth and health
Some organochlorine compounds, such as polychlorinated biphenyls (PCBs), have a tendency to bioaccumulate in humans and predators at the top of the food chain. We have recently confirmed the transplacental transfer of these compounds and the present study has been designed on the same material with the aim of investigating their potential health effects on newborns from 70 pregnant women, resident in a Northern Italy industrial town. Organochlorine compounds [namely, p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), p,p'-dichlorodiphenyldichloroethene (p,p'-DDE), hexachlorobenzene (HCB), and PCBs] have been analyzed both in cord and maternal serum, placenta, and maternal subcutaneous adipose tissue by GC-MSD. p,p'-DDT levels in the adipose tissue resulted significantly (p<0.05) related to birth length. Mothers of neonates born by preterm programmed caesarean delivery showed significantly (p<0.005 for both) higher serum p,p'-DDE serum concentrations and p,p'-DDT levels in the adipose tissue, as compared to mothers delivering at term
Decomposição da matéria orgânica de compostos de lixo urbano e posterior preparo de extratos nítrico-perclórico.
Pré-digestão de amostras de compostos. Desempenhos dos Pré tratamentos de Amostras: Peróxido de Hidrogênio ( H2O2) Versus aquecimento em mufla a 550ºC. Digestão Nítrico-perclórica de compostos de lixo urbano. Resultados analíticos de compostos de lixo usando-se a técnica de eliminação da fração orgânica e a digestão Nítrico-perclórica propostas. Metodologia Padronizada por Silva (1999), Recomendada pela Embrapa. Pré-digestão da amostra de composto utilizando-se H²O² a 30%bitstream/CNPTIA/9196/1/CIRCULARTECNICA1int.pdfAcesso em: 28 maio 2008
The complex TIE between macrophages and angiogenesis
Macrophages are primarily known as phagocytic immune cells, but they also play a role in diverse processes, such as morphogenesis, homeostasis and regeneration. In this review, we discuss the influence of macrophages on angiogenesis, the process of new blood vessel formation from the pre-existing vasculature. Macrophages play crucial roles at each step of the angiogenic cascade, starting from new blood vessel sprouting to the remodelling of the vascular plexus and vessel maturation. Macrophages form promising targets for both pro- and anti-angiogenic treatments. However, to target macrophages, we will first need to understand the mechanisms that control the functional plasticity of macrophages during each of the steps of the angiogenic cascade. Here, we review recent insights in this topic. Special attention will be given to the TIE2-expressing macrophage (TEM), which is a subtype of highly angiogenic macrophages that is able to influence angiogenesis via the angiopoietin-TIE pathway
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