Hybrid photonic entanglement: Realization, characterization and applications

We show that the quantum disentanglement eraser implemented on a two-photon system from parametric down-conversion is a general method to create hybrid photonic entanglement, namely the entanglement between different degrees of freedom of the photon pair. To demonstrate this, we generate and characterize a source with tunable degree of hybrid entanglement between two qubits, one encoded in the transverse momentum and position of a photon, and the other in the polarization of its partner. In addition, we show that a simple extension of our setup enables the generation of two-photon qubit-qudit hybrid entangled states. Finally, we discuss the advantages that this type of entanglement can bring for an optical quantum network.Comment: Published versio

Epidemiologia de fraturas osteoporóticas no serviço de urgência dos CHUC

Trabalho final de mestrado integrado em Medicina, apresentado à Faculdade de Medicina da Universidade de Coimbra.Introdução: As fracturas osteoporóticas ocorrem com maior frequência ao nível do fémur proximal, coluna toraco-lombar, úmero proximal e rádio distal. Como apenas alguns dos doentes com fracturas vertebrais, da tíbia, do úmero ou do antebraço, são sujeitos a tratamento médico em ambiente hospitalar, torna-se extremamente difícil determinar com rigor a real incidência e prevalência destas fracturas. Objetivos: Caracterizar a epidemiologia das fraturas osteoporóticas observadas no SU do CHUC – polo HUC, caracterizar o estado funcional, tempo de recuperação e recursos médicos utilizados após a fratura e avaliar a prescrição de fármacos anti-osteoporóticos. Materiais e métodos: Procedeu-se a um estudo transversal, no qual foram identificados todos os doentes com mais de 50 anos que tiveram um diagnóstico/ avaliação por parte da ortopedia no serviço de urgência dos HUC no período entre 1 de Abril e 30 de Junho de 2013. Por verificação manual recorrendo-se ao Alert, verificaram-se todos os registos desses doentes para identificação de fraturas que poderiam estar descritas como diagnóstico final ou nas notas clínicas. Procedeu-se de seguida a um inquérito telefónico previamente validado a uma sub amostra selecionada aleatoriamente de cada tipo de fratura (rádio, úmero, coluna vertebral e tíbia) para colheita de dados sócio demográficos e clínicos aplicação do .EuroQol-5 Dimensions (EQ-5D) e fatores clínicos incluídos no algoritmo FRAX. O tratamento estatístico dos dados foi realizado com recurso ao software SPSS® 19.0 e ao Excel. Resultados: Foram incluídos 435 doentes com fracturas confirmadas. Destas 129 eram fraturas da anca que não foram posteriormente estudados. A amostra consiste em 306 fraturas agrupadas em 5 grupos: 26 fraturas vertebrais , 26 fraturas úmero, 100 fraturas rádio, 49 fraturas tíbia/perónio, 105 outras fraturas. Foram contactados aleatoriamente e tendo por base o número inicial de fraturas, 50 doentes com fraturas (20 rádio,10 úmero, 10 tíbia e 10 fraturas vertebrais) Nos quatro grupos houve um predomínio de doentes do sexo feminino com média de idades a variar entre 68,5 anos (rádio), 68,7 anos (úmero), 63 anos (tíbia) e 71,2 anos (fraturas vertebrais) . A fratura do rádio é aquela onde se observa um maior número de doentes sem fatores de risco (35%), as fraturas vertebrais são aquelas que apresentam maior proporção de doentes com mais de 4 fatores de risco (10%). Dos 50 doentes em estudo 98% referiram que a fratura decorreu de uma queda. Mais de metade (60%) dos doentes apresentavam indicação clara para tratamento antes da fratura utilizando o algoritmo FRAX. Contudo após a fratura apenas 5 doentes (10%) estavam a fazer tratamento antiosteoporotico, sendo que só 2 doentes estavam a ser tratado com bifosfonatos e os restantes apenas com cálcio e Vitamina D. Após o episódio de fratura 94% dos doentes foram acompanhados em consulta de Medicina Geral e Familiar ou de Ortopedia. Observa-se um declínio em todas as dimensões do EQ-D5 um ano após a ocorrência da fratura, tendo por base o estado funcional do doente antes do episódio traumático. Conclusão: A maioria das fraturas osteoporóticas ocorreu em indivíduos com fatores de risco conhecidos, sendo portanto passíveis de prevenção. Contudo a maioria dos doentes deste estudo não recebeu qualquer tipo de tratamento preventivo da osteoporose após a alta do CHUC.Introduction: The osteoporotic fractures occur with greater frequency at the level of the proximal femur, thoraco-lumbar column, proximal humerus and distal radius. As only some of the patients with vertebral fractures, the tibia, humerus or forearm, are subject to medical treatment in a hospital environment, it is extremely difficult to determine with accuracy the actual incidence and prevalence of these fractures. Aim: Characterize the epidemiology of osteoporotic fractures observed in SU of the CHUC - polo HUC, characterize the functional status, recovery time and medical resources used after fracture and assess the prescription of anti-osteoporotic drugs. Patients and methods: There was a cross-sectional study, in which they were raised all patients with more than 50 years of age who have had a diagnosis/evaluation by the orthopedics in emergency service of HUC in the period between 1 April and June 30, 2013. By manually checking using the Alert, there were checked all the records of these patients for identification of fractures. There was then a telephone interview, previously validated in a sub sample selected at random from each type of fracture (radius, humerus, vertebral and tibia), for data collection regarding demographic and clinical application of EuroQol-5 Dimensions (EQ-5D). Clinical factors were included in FRAX algorithm. The statistical treatment of the data was performed using the software SPSS® 19.0 and Excel. Results: Were included 435 patients with fractures confirmed. Of these, 129 were fractures of the hip that were not subsequently studied. The sample consists of 306 fractures grouped into 5 groups: 26 vertebral fractures, 26 humerus fractures, 100 radius fractures, 49 fractures tibia/fibula fractures and 105 other fractures. Were contacted 50 patients with fractures (20 radius,10 humerus, 10 tibia and 10 vertebral fractures). In the four groups there was a predominance of female patients, with mean ages ranging from 68.5 years (radio), 68.7 years (humerus), 63 years (tibia) and 71.2 years (vertebral fractures). The fracture of the radius is the one where there is a greater number of patients with no risk factors (35 %) while the vertebral fractures are those that have a higher proportion of patients with more than 4 risk factors (10 % ). Of the 50 patients, 98% reported that the fracture was due to a fall. More than half (60 %) patients had clear indication for treatment before the fracture used the FRAX algorithm. However after the fracture only 5 patients (10 %) were doing anti-osteoporosis drugs, 2 of them were being treated with bisphosphonates while the others were treated only with calcium and vitamin D. After the fracture’s episode, 94% of patients were followed up in consultation of General Practitioner or Orthopedics. There is a decline in all the dimensions of EQ-D5 one year after the occurrence of fracture, based on the functional status of the patient before the traumatic episode. Conclusions; The majority of osteoporotic fractures occurred in individuals with known risk factors, and therefore are preventable. However the majority of patients in this study did not receive any type of preventive treatment for osteoporosis after the medical high of the CHU

Context-aware Adversarial Attack on Named Entity Recognition

In recent years, large pre-trained language models (PLMs) have achieved remarkable performance on many natural language processing benchmarks. Despite their success, prior studies have shown that PLMs are vulnerable to attacks from adversarial examples. In this work, we focus on the named entity recognition task and study context-aware adversarial attack methods to examine the model's robustness. Specifically, we propose perturbing the most informative words for recognizing entities to create adversarial examples and investigate different candidate replacement methods to generate natural and plausible adversarial examples. Experiments and analyses show that our methods are more effective in deceiving the model into making wrong predictions than strong baselines

Generation of maximally entangled states of qudits using twin photons

We report an experiment to generate maximally entangled states of D-dimensional quantum systems, qudits, by using transverse spatial correlations of two parametric down-converted photons. Apertures with D-slits in the arms of the twin fotons define the qudit space. By manipulating the pump beam correctly the twin photons will pass only by symmetrically opposite slits, generating entangled states between these differents paths. Experimental results for qudits with D=4 and D=8 are shown. We demonstrate that the generated states are entangled states.Comment: 04 pages, 04 figure

Quantifying Complementarity among Strategies for Influencers’ Detection on Twitter1

AbstractThe so-called influencer, a person with the ability to persuade people, have important role on the information diffusion in social media environments. Indeed, influencers might dictate word- of-mouth and peer recommendation, impacting tasks such as recommendation, advertising, brand evaluation, among others. Thus, a growing number of works aim to identify influencers by exploiting distinct information. Deciding about the best strategy for each domain, however, is a complex task due to the lack of consensus among these works. This paper presents a quantitative study of analysis among some of the main strategies for identifying influencers, aiming to help researchers on this decision. Besides determining semantic classes of strategies, based on the characteristics they exploit, we obtained through PCA an effective meta-learning process to combine linearly distinct strategies. As main implications, we highlight a better understanding about the selected strategies and a novel manner to alleviate the difficulty on deciding which strategy researchers would adopt