90 research outputs found
Optimal estimation of SU(d) using exact and approximate 2-designs
We consider the problem of estimating an SU(d) quantum operation when n
copies of it are available at the same time. It is well known that, if one uses
a separable state as the input for the unitaries, the optimal mean square error
will decrease as 1/n. However it is shown here that, if a proper entangled
state is used, the optimal mean square error will decrease at a 1/n^2 rate. It
is also shown that spherical 2-designs (e.g. complete sets of mutually unbiased
bases and symmetric informationally complete positive operator valued measures)
can be used to design optimal input states. Although 2-designs are believed to
exist for every dimension, this has not yet been proven. Therefore, we give an
alternative input state based on approximate 2-designs which can be made
arbitrarily close to optimal. It is shown that measurement strategies which are
based on local operations and classical communication between the ancilla and
the rest of the system can be optimal.Comment: 6 pages. v2: Complete rewrite, new results 11 page
Entanglement is not very useful for estimating multiple phases
The problem of the estimation of multiple phases (or of commuting unitaries)
is considered. This is a sub-model of the estimation of a completely unknown
unitary operation where it has been shown in recent works that there are
considerable improvements by using entangled input states and entangled
measurements. Here it is shown that when estimating commuting unitaries, there
is practically no advantage in using entangled input states or entangled
measurements.Comment: v2. New title, improved Fig.3, other minor changes, Accepted in PR
State Discrimination with Post-Measurement Information
We introduce a new state discrimination problem in which we are given
additional information about the state after the measurement, or more
generally, after a quantum memory bound applies. In particular, the following
special case plays an important role in quantum cryptographic protocols in the
bounded storage model: Given a string x encoded in an unknown basis chosen from
a set of mutually unbiased bases, you may perform any measurement, but then
store at most q qubits of quantum information. Later on, you learn which basis
was used. How well can you compute a function f(x) of x, given the initial
measurement outcome, the q qubits and the additional basis information? We
first show a lower bound on the success probability for any balanced function,
and any number of mutually unbiased bases, beating the naive strategy of simply
guessing the basis. We then show that for two bases, any Boolean function f(x)
can be computed perfectly if you are allowed to store just a single qubit,
independent of the number of possible input strings x. However, we show how to
construct three bases, such that you need to store all qubits in order to
compute f(x) perfectly. We then investigate how much advantage the additional
basis information can give for a Boolean function. To this end, we prove
optimal bounds for the success probability for the AND and the XOR function for
up to three mutually unbiased bases. Our result shows that the gap in success
probability can be maximal: without the basis information, you can never do
better than guessing the basis, but with this information, you can compute f(x)
perfectly. We also exhibit an example where the extra information does not give
any advantage at all.Comment: twentynine pages, no figures, equations galore. v2 thirtyone pages,
one new result w.r.t. v
Entropic uncertainty relations and locking: tight bounds for mutually unbiased bases
We prove tight entropic uncertainty relations for a large number of mutually
unbiased measurements. In particular, we show that a bound derived from the
result by Maassen and Uffink for 2 such measurements can in fact be tight for
up to sqrt{d} measurements in mutually unbiased bases. We then show that using
more mutually unbiased bases does not always lead to a better locking effect.
We prove that the optimal bound for the accessible information using up to
sqrt{d} specific mutually unbiased bases is log d/2, which is the same as can
be achieved by using only two bases. Our result indicates that merely using
mutually unbiased bases is not sufficient to achieve a strong locking effect,
and we need to look for additional properties.Comment: 9 pages, RevTeX, v3: complete rewrite, new title, many new results,
v4: minor changes, published versio
Estimating the spectrum of a density matrix with LOCC
The problem of estimating the spectrum of a density matrix is considered.
Other problems, such as bipartite pure state entanglement, can be reduced to
spectrum estimation. A local operations and classical communication (LOCC)
measurement strategy is shown which is asymptotically optimal. This means that,
for a very large number of copies, it becomes unnecessary to perform collective
measurements which should be more difficult to implement in practice.Comment: 12 pages, uses iopart.cls and iopart10.clo. Improved version. v3:
Reference updated, added journal referenc
Estimation of unitary quantum operations
The problem of optimally estimating an unknown unitary quantum operation with
the aid of entanglement is addressed. The idea is to prepare an entangled pair,
apply the unknown unitary to one of the two parts and then measure the joint
output state. This measurement could be an entangled one or it could be
separable (e.g., LOCC). A comparison is made between these possibilities and it
is shown that by using non-separable measurements one can improve the accuracy
of the estimation by a factor of where is the dimension of the
Hilbert space on which acts.Comment: 6 pages. Revised version. Typos corrected. Some discussion added.
Reference fixe
Evaluation of protective effect of different dietary fibers on polyphenolic profile stability of maqui berry (Aristotelia chilensis (Molina) Stuntz) during in vitro gastrointestinal digestion
The aim of this work was to determine the protective effect of different dietary fibers on (i) the recovery
and bioaccessibility indexes, and (ii) the stability of polyphenolic compounds (phenolic acids, flavonoids
and anthocyanins) of maqui berry powder subjected to in vitro gastrointestinal digestion (GID). The
extracts obtained in each phase (oral, gastric and intestinal) of GID were used to analyze the stability of
polyphenolic compounds by HPLC, and the bioaccessibility of these compounds was also determined. At
the end of the GID process, the mixture of maqui berry with the different fibers increased the bioaccessibility
index of the phenolic and flavonoid compounds in all cases. The results obtained suggest that the
anthocyanins and phenolic acids and flavonoid compounds present in maqui are stabilized through
dietary fiber interactions, which might provide sufficient levels for absorption during gastrointestinal
digestion. The gums sodium carboxymethyl cellulose, xanthan gum and guar gum provided the best protective
effect
Dielectric properties of colon polyps, cancer, and normal mucosa: Ex vivo measurements from 0.5 to 20 GHz
This is the accepted version of the following article: Guardiola, M. , Buitrago, S. , Fernández‐Esparrach, G. , O'Callaghan, J. M., Romeu, J. , Cuatrecasas, M. , Córdova, H. , González Ballester, M. Á. and Camara, O. (2018), Dielectric properties of colon polyps, cancer, and normal mucosa: Ex vivo measurements from 0.5 to 20 GHz. Med. Phys., 45: 3768-3782. doi:10.1002/mp.13016, which has been published in final form at https://aapm.onlinelibrary.wiley.com/doi/pdf/10.1002/mp.13016.
This article may be used for non-commercial purposes in accordance with the Wiley Self-Archiving Policy [http://olabout.wiley.com/WileyCDA/Section/id-820227.html].Colorectal cancer is highly preventable by detecting and removing polyps, which are the precursors. 20 Currently, the most accurate test is colonoscopy, but still misses 22% of polyps due to visualization limitations. In this paper we preliminary assess the potential of microwave imaging and dielectric properties (e.g. complex permittivity) as a complementary method for detecting polyps and cancer tissue in the colon. The dielectric properties of biological tissues have been used in a wide variety of applications, including safety assessment of wireless technologies and design of medical diagnostic or therapeutic techniques 25 (microwave imaging, hyperthermia and ablation). The main purpose of this work is to measure the complex permittivity of different types of colon polyps, cancer and normal mucosa in ex vivo human samples to study if the dielectric properties are appropriate for classification purposes.Peer ReviewedPostprint (author's final draft
Dietary intake of bioactive ingredients impacts liver and adipose tissue transcriptomes in a porcine model of prepubertal early obesity
Global prevalence of obesity has increased to epidemic proportions over the past 40 years, with childhood obesity reaching alarming rates. In this study, we determined changes in liver and adipose tissue transcriptomes of a porcine model for prepubertal early obesity induced by a high-calorie diet and supplemented with bioactive ingredients. A total of 43 nine-weeks-old animals distributed in four pens were fed with four different dietary treatments for 10 weeks: a conventional diet; a western-type diet; and a western-type diet with Bifidobacterium breve and rice hydrolysate, either adding or not omega-3 fatty acids. Animals fed a western-type diet increased body weight and total fat content and exhibited elevated serum concentrations of cholesterol, whereas animals supplemented with bioactive ingredients showed lower body weight gain and tended to accumulate less fat. An RNA-seq experiment was performed with a total of 20 animals (five per group). Differential expression analyses revealed an increase in lipogenesis, cholesterogenesis and inflammatory processes in animals on the western-type diet while the supplementation with bioactive ingredients induced fatty acid oxidation and cholesterol catabolism, and decreased adipogenesis and inflammation. These results reveal molecular mechanisms underlying the beneficial effects of bioactive ingredient supplementation in an obese pig model.This work was supported by CDTI (Centro para el desarrollo Tecnológico e Industrial, Spain), Project reference: IPT-20111008, and Generalitat de Catalunya grant 2017SGR1719. M. Ballester is financially supported by a Ramon y Cajal contract (RYC-2013-12573) from the Spanish Ministry of Economy and Competitiveness. We wish to thank all of the members of the IRTA institution who contributed to the generation of the animal material used in this work
Minimally invasive system to reliably characterize ventricular electrophysiology from living donors
Cardiac tissue slices preserve the heterogeneous structure and multicellularity of the myocardium and allow its functional characterization. However, access to human ventricular samples is scarce. We aim to demonstrate that slices from small transmural core biopsies collected from living donors during routine cardiac surgery preserve structural and functional properties of larger myocardial specimens, allowing accurate electrophysiological characterization. In pigs, we compared left ventricular transmural core biopsies with transmural tissue blocks from the same ventricular region. In humans, we analyzed transmural biopsies and papillary muscles from living donors. All tissues were vibratomesliced. By histological analysis of the transmural biopsies, we showed that tissue architecture and cellular organization were preserved. Enzymatic and vital staining methods verifed viability. Optically mapped transmembrane potentials confrmed that action potential duration and morphology were similar in pig biopsies and tissue blocks. Action potential morphology and duration in human biopsies and papillary muscles agreed with published ranges. In both pigs and humans, responses to increasing pacing frequencies and β-adrenergic stimulation were similar in transmural biopsies and larger tissues. We show that it is possible to successfully collect and characterize tissue slices from human myocardial biopsies routinely extracted from living donors, whose behavior mimics that of larger myocardial preparations both structurally and electrophysiologically.Fil: Oliván Viguera, Aida. Universidad de Zaragoza; EspañaFil: Pérez Zabalza, María. Universidad de Zaragoza; EspañaFil: García Mendívil, Laura. Universidad de Zaragoza; EspañaFil: Mountris, Konstantinos A.. Universidad de Zaragoza; EspañaFil: Orós Rodrigo, Sofía. Universidad de Zaragoza; EspañaFil: Ramos Marquès, Estel. Universidad de Zaragoza; EspañaFil: Vallejo Gil, José María. University Hospital Miguel Servet; EspañaFil: Fresneda Roldán, Pedro Carlos. University Hospital Miguel Servet; EspañaFil: Fañanás Mastral, Javier. University Hospital Miguel Servet; EspañaFil: Vázquez Sancho, Manuel. University Hospital Miguel Servet; EspañaFil: Matamala Adell, Marta. University Hospital Miguel Servet; EspañaFil: Sorribas Berjón, Fernando. University Hospital Miguel Servet; EspañaFil: Bellido Morales, Javier André. University Hospital Miguel Servet; EspañaFil: Mancebón Sierra, Francisco Javier. University Hospital Miguel Servet; EspañaFil: Vaca Núñez, Alexánder Sebastián. University Hospital Miguel Servet; EspañaFil: Ballester Cuenca, Carlos. University Hospital Miguel Servet; EspañaFil: Marigil, Miguel Ángel. Hospital San Jorge; EspañaFil: Pastor, Cristina. Aragón Institute of Health Sciences; EspañaFil: Ordovás, Laura. Aragón Agency for Research and Development; España. Universidad de Zaragoza; EspañaFil: Köhler, Ralf. Aragón Institute of Health Sciences; España. Aragón Agency for Research and Development; EspañaFil: Diez, Emiliano Raúl. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Cátedra de Fisiología Humana Normal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Medicina y Biología Experimental de Cuyo; ArgentinaFil: Pueyo, Esther. Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina; España. Universidad de Zaragoza; Españ
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