41 research outputs found

    Operational approach to Bell inequalities: applications to qutrits

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    Bell inequalities can be studied both as constraints in the space of probability distributions and as expectation values of multipartite operators. The latter approach is particularly useful when considering outcomes as eigenvalues of unitary operators. This brings the possibility of exploiting the complex structure of the coefficients in the Bell operators. We investigate this avenue of though in the known case of two outcomes, and find new Bell inequalities for the cases of three outcomes and n=3,4,5n=3,4,5 and 66 parties. We find their corresponding classical bounds and their maximum violation in the case of qutrits. We further propose a novel way to generate Bell inequalities based on a mapping from maximally entangled states to Bell operators and produce examples for different outcomes and number of parties.Comment: 10 pages, no figures. A sign error in Eq.(10), appearing in the published version, has been correcte

    Absolutely Maximally Entangled states, combinatorial designs and multi-unitary matrices

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    Absolutely Maximally Entangled (AME) states are those multipartite quantum states that carry absolute maximum entanglement in all possible partitions. AME states are known to play a relevant role in multipartite teleportation, in quantum secret sharing and they provide the basis novel tensor networks related to holography. We present alternative constructions of AME states and show their link with combinatorial designs. We also analyze a key property of AME, namely their relation to tensors that can be understood as unitary transformations in every of its bi-partitions. We call this property multi-unitarity.Comment: 18 pages, 2 figures. Comments are very welcom

    Vástago recubierto de hidroxiapatita: Revisión a 5 años

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    Se evalúan los resultados clínicos y radiológicos de 65 vástagos femorales recubiertos proximalmente de hidroxiapatita de más de 5 años y la existencia de una clara correlación de los cambios remodelativos con los patrones de estrés estudiados por elementos finitos. La edad media fue de 56 años y la patología preoperativa más frecuente fue la artrosis en 38 caos, seguida de la necrosis aséptica en 15. Se utilizó el protocolo de Johnston y col. y el baremo numérico de Merle D'Aubigné, pasando sobre 18 en la revisión. En el 98,4% no había dolor o era ligero y ocasional. Radiográficamente se vieron líneas radiolúcidas alrededor de la parte distal del vástago pulida y afilada en el 89,2%, no apareciendo en las zonas recubiertas de hidroxiapatita. Apareció hipertrofia cortical reactiva en el 13,8% y pequeñas imágenes de osteólisis a nivel proximal en el 10,8 %. Según los criterios de Neg. el 100% de los vástagos estaban osteointegrados.The clinical and radiological results of 65 proximally HA-coated femoral stems were assessed after a minimum follow-up period of five years. The relationship between remodelative changes and the stress patterns was clearly disclosed by finite element modelling. Mean age was 56 years. The most common etiology was osteoarthritis in 38 cases and vascular necrosis in 15. Radiographic and clinical assessment was done after Johnston and col's protocol and the numeric rating of Merle D'Aubigne respectively. The mean preoperative score was 8,5 points, becoming 17,4 points out of 18 at the 5 years review. Occasional or absent pain was fount in 98% of the cases. There were radiolucency lines surrounding the polished and sharp distal stem in 89%, but they were not present at the HA-coated zones. Reactive cortical hypertrophy was present in 14 % and proximal small osteolytics features in 11%. According Engh's criteria, the 100% of the stems were osteintegrated

    Coarse-grained entanglement classification through orthogonal arrays

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    Classification of entanglement in multipartite quantum systems is an open problem solved so far only for bipartite systems and for systems composed of three and four qubits. We propose here a coarse-grained classification of entanglement in systems consisting of NN subsystems with an arbitrary number of internal levels each, based on properties of orthogonal arrays with NN columns. In particular, we investigate in detail a subset of highly entangled pure states which contains all states defining maximum distance separable codes. To illustrate the methods presented, we analyze systems of four and five qubits, as well as heterogeneous tripartite systems consisting of two qubits and one qutrit or one qubit and two qutrits.Comment: 38 pages, 1 figur

    Disappearing in the night: an overview on trade and legislation of night monkeys in South and Central America

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    The international trade in night monkeys (Aotus spp.), found throughout Central and South America, has been regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) since 1975. We present a quantitative analysis of this trade from all 9 range countries, over 4 decades, and compare domestic legislation to CITES regulations. Night monkeys were exported from 8 of the 9 habitat countries, totalling 5,968 live individuals and 7,098 specimens, with trade of live individuals declining over time. In terms of species, the most commonly traded was Aotus nancymaae (present in Brazil, Colombia, Peru) followed by A. vociferans (Brazil, Colombia, Ecuador, Peru) and A. zonalis (Colombia, Panama). There was no significant correlation between levels of trade and species' geographic range size or the number of countries in which a species occurs. Five countries have legislation that meets CITES requirements for implementation, whereas the other 4 countries' legislation showed deficiencies. Research conducted in Colombia, Peru, and Brazil suggests significant cross-border trade not captured in official international trade registers. Although international trade has diminished, current trends suggest that populations of rarer species may be under unsustainable pressure. Further research is needed to quantify real trade numbers occurring between habitat countries

    Antiprogestin mifepristone inhibits the growth of cancer cells of reproductive and non-reproductive origin regardless of progesterone receptor expression

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    <p>Abstract</p> <p>Background</p> <p>Mifepristone (MF) has been largely used in reproductive medicine due to its capacity to modulate the progesterone receptor (PR). The study of MF has been expanded to the field of oncology; yet it remains unclear whether the expression of PR is required for MF to act as an anti-cancer agent. Our laboratory has shown that MF is a potent inhibitor of ovarian cancer cell growth. In this study we questioned whether the growth inhibitory properties of MF observed in ovarian cancer cells would translate to other cancers of reproductive and non-reproductive origin and, importantly, whether its efficacy is related to the expression of cognate PR.</p> <p>Methods</p> <p>Dose-response experiments were conducted with cancer cell lines of the nervous system, breast, prostate, ovary, and bone. Cultures were exposed to vehicle or increasing concentrations of MF for 72 h and analysed for cell number and cell cycle traverse, and hypodiploid DNA content characteristic of apoptotic cell death. For all cell lines, expression of steroid hormone receptors upon treatment with vehicle or cytostatic doses of MF for 24 h was studied by Western blot, whereas the activity of the G1/S regulatory protein Cdk2 in both treatment groups was monitored <it>in vitro </it>by the capacity of Cdk2 to phosphorylate histone H1.</p> <p>Results</p> <p>MF growth inhibited all cancer cell lines regardless of tissue of origin and hormone responsiveness, and reduced the activity of Cdk2. Cancer cells in which MF induced G1 growth arrest were less susceptible to lethality in the presence of high concentrations of MF, when compared to cancer cells that did not accumulate in G1. While all cancer cell lines were growth inhibited by MF, only the breast cancer MCF-7 cells expressed cognate PR.</p> <p>Conclusions</p> <p>Antiprogestin MF inhibits the growth of different cancer cell lines with a cytostatic effect at lower concentrations in association with a decline in the activity of the cell cycle regulatory protein Cdk2, and apoptotic lethality at higher doses in association with increased hypodiploid DNA content. Contrary to common opinion, growth inhibition of cancer cells by antiprogestin MF is not dependent upon expression of classical, nuclear PR.</p
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