Papers by thiago araujo maciel
Quantum Information and Computation
We develop a quantum process tomography method, which variationally reconstruct the map of a proc... more We develop a quantum process tomography method, which variationally reconstruct the map of a process, using noisy and incomplete information about the dynamics. The new method encompasses the most common quantum process tomography schemes. It is based on the variational quantum tomography method (VQT) proposed by Maciel \emph{et al.} in arXiv:1001.1793[quant-ph] \cite{VQT}.
Cornell University - arXiv, Jul 8, 2014
One of the goals of probabilistic inference is to decide whether an empirically observed distribu... more One of the goals of probabilistic inference is to decide whether an empirically observed distribution is compatible with a candidate Bayesian network. However, Bayesian networks with hidden variables give rise to highly non-trivial constraints on the observed distribution. Here, we propose an information-theoretic approach, based on the insight that conditions on entropies of Bayesian networks take the form of simple linear inequalities. We describe an algorithm for deriving entropic tests for latent structures. The well-known conditional independence tests appear as a special case. While the approach applies for generic Bayesian networks, we presently adopt the causal view, and show the versatility of the framework by treating several relevant problems from that domain: detecting common ancestors, quantifying the strength of causal influence, and inferring the direction of causation from two-variable marginals.
Revista De Educacao Continuada Em Medicina Veterinaria E Zootecnia, 2014
Foram comparados os dados goniometricos de membros pelvicos de cabras da raca Saanen visando o es... more Foram comparados os dados goniometricos de membros pelvicos de cabras da raca Saanen visando o estabelecimento de valores de normalidade para caracterizacao das articulacoes da especie. Foram utilizados 15 caprinos higidos da raca Saanen, femeas, com idade de tres anos e 10 animais de 6 meses. Foram medidos os ângulos das articulacoes em maxima extensao e maxima flexao e as respectivas amplitudes de movimentos articulares dos membros pelvicos. Os ângulos foram medidos com um goniometro universal de plastico com os animais em estacao onde se fazia manualmente os movimentos de extensao e flexao das articulacoes da coxa, do joelho e do tarso. A articulacao sinovial e a unica que permite movimentos livres como deslizamento, aducao, abducao, extensao e flexao. Dentre os metodos utilizados para avaliacao da capacidade de amplitude de movimento, a goniometria tem as vantagens de simplicidade e baixo custo. Os resultados foram tabulados e submetidos a analise estatistica, onde se avaliou diferencas entre os antimeros e as idades dos animais, por meio de analise de variância. Foi observado que os ângulos de flexao de todas as articulacoes estudadas diferiram entre as idades, mostrando que alem da influencia da morfologia das estruturas articulares, o desenvolvimento muscular tambem parece interferir nos dados goniometricos normais dos caprinos. Essa diferenca nos ângulos de flexao refletiu tambem na diferenca da amplitude dos movimentos do joelho e do tarso entre as idades. Diante do exposto, conclui-se que os dados goniometricos do membro toracico de cabras Saanen apresentam diferencas conforme a faixa etaria.
Revista De Educacao Continuada Em Medicina Veterinaria E Zootecnia, 2014
O presente trabalho empregou tecnicas de imuno-histoquimica e citoquimica para avaliar a presenca... more O presente trabalho empregou tecnicas de imuno-histoquimica e citoquimica para avaliar a presenca de componentes-chave para o desenvolvimento da contratura articular na especie ovina e a potencialidade desta especie como modelo experimental para estudo desta patologia. Para tanto, foram utilizadas 15 capsulas articulares de joelhos de ovelhas Santa Ines sadias para localizacao de miofibroblastos e mastocitos. Para investigacao de miofibroblastos foi realizada a tecnica de imuno-histoquimica. Apos a preparacao para rotina histologica, a recuperacao antigenica foi realizada por aquecimento em citrato, seguida pelo bloqueio das peroxidades, bloqueio de proteinas inespecificas e entao, o anticorpo primario foi incubado. Apos, o anticorpo secundario foi acrescentado aos cortes, e o cromogeno DAB foi adicionado. As lâminas foram contracoradas com Hematoxilina de Harris e montadas. Na tecnica citoquimica, foi aplicada a coloracao de Azul de Toluidina para evidenciacao dos mastocitos. As analises dos cortes foram efetuadas em microscopio de luz. As contraturas articulares sao complicacoes severas de doencas articulares que podem limitar permanentemente a funcao de extremidades. A articulacao do ovino e um modelo promissor para a investigacao dos estados normais e patologicos, pela semelhanca com a biomecânica de determinadas articulacoes humanas. Os controles positivos da pesquisa de α-SMA (cervix ovina) e de mastocitos (cordao umbilical) foram marcados ou corados satisfatoriamente pelas respectivas tecnicas. Nas capsulas articulares, a proteina foi observada na parede de arterias e raros miofibroblastos foram observados em cada corte, assim como poucos mastocitos foram corados. Outros estudos sobre lesoes de capsula articular de ovinos devem ser conduzidos para confirmar a presenca de miofibroblastos e o desenvolvimento da contratura articular.
Cadernos De Agroecologia, Feb 22, 2015
: O sistema agroflorestal (SAF) permite desenvolver atividade agricola e pecuaria. O objetivo do ... more : O sistema agroflorestal (SAF) permite desenvolver atividade agricola e pecuaria. O objetivo do presente trabalho foi avaliar a fitossociologia, a estrutura e o desempenho das especies arboreas em um SAF implantado em Itaquirai-MS. Nas avaliacoes fitossociologicas foram analisados 88 individuos, pertencentes a 12 especies e 06 familias botânicas. Os parâmetros avaliados foram: Densidade Absoluta (DA), Densidade Relativa (DR), Frequencia Absoluta (FA), Frequencia Relativa (FR), Dominância Absoluta (DoA), Dominância Relativa (DoR), Indice de Valor de Importância (IVI) e Indice de Valor de Cobertura (IVC). Os dados foram analisados utilizando o software FITOPAC 2.1. O Indice de diversidade de Shannon (‘H) foi de 2,19 com um indice de Equabilidade (J’) de 0,854, o que representa baixa diversidade floristica. As especies arboreas Cecropia pachystachya (embauba), Inga laurina (inga), Handroanthus impetiginosus (ipe-roxo), Pterogyne nitens (amendoim-bravo), apresentaram os maiores valores de IVI e IVC
New Journal of Physics, 2015
We reconstruct the time dependent quantum map corresponding to the relaxation process of a two-sp... more We reconstruct the time dependent quantum map corresponding to the relaxation process of a two-spin system in liquid-state NMR at room temperature. By means of quantum tomography techniques that handle informational incomplete data, we show how to properly post-process and normalize the measurements data for the simulation of quantum information processing, overcoming the unknown number of molecules prepared in a non-equilibrium magnetisation state (N j) by an initial sequence of radiofrequency (RF) pulses. From the reconstructed quantum map, we infer both longitudinal (T 1) and transversal (T 2) relaxation times, and introduce the J-coupling relaxation times (T J 1 , T J 2), which are relevant for quantum information processing simulations. We show that the map associated to the relaxation process cannot be assumed approximated unital and trace-preserving for times greater than T J 2 .
Journal of nephrology
Extracellular matrix accumulation, epithelial-to-mesenchymal transition, tubular atrophy and loss... more Extracellular matrix accumulation, epithelial-to-mesenchymal transition, tubular atrophy and loss of peritubular capillary network are hallmarks of tubulointerstitial injury in progressive renal diseases. In this study, we analyzed endostatin expression in kidneys subjected to unilateral ureteral obstruction (UUO). Collagen XVIII mRNA expression was evaluated by real-time polymerase chain reaction (PCR). Endostatin and CD31 protein levels were analyzed by Western blot and immunohistochemistry. In vitro quantification of collagen XVIII and fibrosis-related genes in HK2 cells was performed by real-time PCR. UUO significantly increased collagen XVIII mRNA expression and released a 30-kDa endostatin fragment. Immunohistochemistry revealed endostatin expression increased in injured tissue, mainly on tubular cells. Of interest, expression of CD31 was significantly reduced by UUO. Endostatin administration in vitro did not modify the expression of genes related to fibrosis development. How...
It is assumed partial knowledge about the state of a quantum system. This knowledge is represente... more It is assumed partial knowledge about the state of a quantum system. This knowledge is represented by the results of some measurements, spanning a certain subspace. We refer to this subspace as the known subspace, and to its complement as the unknown one. Then we introduce a variational method to estimate the expectation value of every observable. This estimate is
Critical Care, 2003
CARDIOLOGY P1 Impact of peroperative administration of steroid over inflammatory response and pul... more CARDIOLOGY P1 Impact of peroperative administration of steroid over inflammatory response and pulmonary dysfunction following cardiac surgery
International Journal of Modern Physics C, 2011
We introduce a new method to reconstruct unknown quantum states out of incomplete and noisy infor... more We introduce a new method to reconstruct unknown quantum states out of incomplete and noisy information. The method is a linear convex optimization problem, therefore with a unique minimum, which can be efficiently solved with Semidefinite Programs. Numerical simulations indicate that the estimated state does not overestimate purity, and neither the expectation value of optimal entanglement witnesses. The convergence properties of the method are similar to compressed sensing approaches, in the sense that, in order to reconstruct low rank states, it needs just a fraction of the effort corresponding to an informationally complete measurement.
Ciência Animal Brasileira, 2014
A cérvice ovina tem formato irregular, tornando um desafio transpassá-la durante a inseminação ar... more A cérvice ovina tem formato irregular, tornando um desafio transpassá-la durante a inseminação artificial. Logo, este trabalho teve por objetivo descrever as características morfológicas da cérvice de ovelhas da raça Santa Inês, comparando-se as fases do ciclo estral. Foram coletados 112 úteros de ovelhas adultas não gestantes e silicone foi injetado no lúmen da cérvice obtendo-se um molde do canal cervical. O comprimento médio foi de 41,33± 16,38 mm e o tipo de óstio cervical mais frequente foi o bico-de-pato (46%). O número mínimo de anéis encontrados nas cérvices foi de dois e o máximo de sete, com média de 4,70 ± 1,05 anéis. A morfometria de cada anel cervical indica que a circunferência interna se afunila na porção média e em seguida torna a aumentar. Não houve diferença significativa (p>0,05) quando se compararam as fases luteínica e folicular e entre os tipos de cérvice quanto ao diâmetro das dobras, altura das dobras, circunferência interna, ponto médio entre as dobras e ...
Motrivivência, 2014
O presente estudo propôs investigar o conteúdo e a forma, em tempos de megaeventos, das políticas... more O presente estudo propôs investigar o conteúdo e a forma, em tempos de megaeventos, das políticas públicas de esportes em um município do interior de Minas Gerais e a possibilidade de acesso da população, em especial a classe trabalhadora. Valendo-se do materialismo histórico utilizou-se como instrumentos metodológicos a busca por documentos em órgãos oficiais da prefeitura do município; visitas a bairros da cidade e as suas estruturas para desenvolvimento dos esportes e outros elementos da cultura corporal, foto-registro e relatórios; por fim foram entrevistados interlocutores privilegiados, a fim de compreender o estado da arte das políticas públicas na cidade.
Quantum Information Processing, 2012
We present a method to quantify quantum correlations in arbitrary systems of indistinguishable fe... more We present a method to quantify quantum correlations in arbitrary systems of indistinguishable fermions using witness operators. The method associates the problem of finding the optimal entanglement witness of a state with a class of problems known as semidefinite programs (SDPs), which can be solved efficiently with arbitrary accuracy. Based on these optimal witnesses, we introduce a measure of quantum correlations which has an interpretation analogous to the Generalized Robustness of entanglement. We also extend the notion of quantum discord to the case of indistinguishable fermions, and propose a geometric quantifier, which is compared to our entanglement measure. Our numerical results show a remarkable equivalence between the proposed Generalized Robustness and the Schliemann concurrence, which are equal for pure states. For mixed states, the Schliemann concurrence presents itself as an upper bound for the Generalized Robustness. The quantum discord is also found to be an upper bound for the entanglement.
Quantum Information Processing, 2011
Entanglement witnesses (EW) allow the detection of entanglement in a quantum system, from the mea... more Entanglement witnesses (EW) allow the detection of entanglement in a quantum system, from the measurement of some few observables. They do not require the complete determination of the quantum state, which is regarded as a main advantage. On this paper it is experimentally analyzed an entanglement witness recently proposed in the context of Nuclear Magnetic Resonance (NMR) experiments to test it in some Bell-diagonal states. We also propose some optimal entanglement witness for Bell-diagonal states. The efficiency of the two types of EW's are compared to a measure of entanglement with tomographic cost, the generalized robustness of entanglement. It is used a GRAPE algorithm to produce an entangled state which is out of the detection region of the EW for Bell-diagonal states. Upon relaxation, the results show that there is a region in which both EW fails, whereas the generalized robustness still shows entanglement, but with the entanglement witness proposed here with a better performance.
Physical Review A, 2012
We establish relations between geometric quantum discord and entanglement quantifiers obtained by... more We establish relations between geometric quantum discord and entanglement quantifiers obtained by means of optimal witness operators. In particular, we prove a relation between negativity and geometric discord in the Hilbert-Schmidt norm, which is slightly different from a previous conjectured one [1]. We also show that, redefining the geometric discord with the trace norm, better bounds can be obtained. We illustrate our results numerically.
Physical Review A, 2013
Whenever we do not have an informationally complete set of measurements, the estimate of a quantu... more Whenever we do not have an informationally complete set of measurements, the estimate of a quantum state can not be uniquely determined. In this case, among the density matrices compatible with the available data, it is commonly preferred that one which is the most uncommitted with the missing information. This is the purpose of the Maximum Entropy estimation (MaxEnt) and the Variational Quantum Tomography (VQT). Here, we propose a variant of Variational Quantum Tomography and show its relationship with Maximum Entropy methods in quantum tomographies with incomplete set of measurements. We prove their equivalence in case of eigenbasis measurements, and through numerical simulations we stress their similar behavior. Hence, in the modified VQT formulation we have an estimate of a quantum state as unbiased as in MaxEnt and with the benefit that VQT can be more efficiently solved by means of linear semidefinite programs.
Physical Review A, 2013
An experimental demonstration of two-qutrit state tomography via one-qutrit symmetric information... more An experimental demonstration of two-qutrit state tomography via one-qutrit symmetric informationally complete positive operator-valued measure (SIC-POVM) is presented. A two-qutrit state is encoded in the transversal paths of a spontaneous parametric down-converted photon pair. A spatial light modulator allows to implement the necessary 81 POVM elements to reconstruct the state. The quality of the reconstruction is evaluated by comparing independent measurements with the predicted results calculated with the reconstructed state. Entanglement in the system is calculated via negativity and generalized robustness from the two-qutrit reconstructed density operator.
Physical Review A, 2009
We explore procedures to detect entanglement of unknown mixed states, which can be experimentally... more We explore procedures to detect entanglement of unknown mixed states, which can be experimentally viable. The heart of the method is a hierarchy of simple feasibility problems, which provides sufficient conditions to entanglement. Our numerical investigations indicate that the entanglement is detected with a cost which is much lower than full state tomography. The procedure is applicable to both free and bound entanglement, and involves only single copy measurements.
Physical Review A, 2013
We show that the mistakes pointed out by Rana and Parashar [Phys. Rev. A 87, 016301 (2013)] do no... more We show that the mistakes pointed out by Rana and Parashar [Phys. Rev. A 87, 016301 (2013)] do not invalidate the main conclusion of our work [Phys. Rev. A 86, 024302 (2012)]. We show that the errors affected only a particular application of our general results, and present the correction.
Nephrology, 2007
Background: Renal ischaemia-hypoxia is a leading cause of acute renal failure, a clinical conditi... more Background: Renal ischaemia-hypoxia is a leading cause of acute renal failure, a clinical condition associated with rapid loss of renal function and high rates of mortality. Renal proximal tubular cells are the most severely injured during renal ischaemia, caused by the breakdown of the extracellular matrix of the tubular basement membrane. Endostatin is the C-terminal fragment of collagen XVIII generated by proteolytic cleavage and it is well-known as being an inhibitor of angiogenesis. In vitro, endostatin inhibits endothelial cell proliferation and migration, as well as tubule formation. In vivo, it has a potent inhibitory effect on tumour growth. In this study, we analysed endostatin gene expression in C57BL/6 mouse kidneys subjected to ischaemia/reperfusion. Methods: Ischaemic renal failure was induced via 45 min of bilateral occlusion of the renal artery and vein, followed by 12 h or 24 h of reperfusion. Whole-kidney homogenate and total RNA were extracted for examination by western blot analysis and quantitative polymerase chain reaction. The immunohistological examination revealed increased endostatin expression in injured kidney, mainly in the proximal tubule and collecting ducts. Results: Endostatin/collagen XVIII mRNA and protein expression increased during ischaemia and within 12 h of reperfusion. In the western blot assay, we identified increased expression of the 30 kDa endostatin-related fragment and of matrix metalloproteinase-9. CD31 was significantly expressed during reperfusion (P < 0.05). Immunohistological examination revealed glomerular and tubulointerstitial expression of endostatin. Conclusion: These data suggest the local synthesis of a 30 kDa endostatin-related fragment following acute renal failure and suggest its role in the modulation of renal capillary density.
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Papers by thiago araujo maciel