Bayesian feedback versus Markovian feedback in a two-level atom

We compare two different approaches to the control of the dynamics of a continuously monitored open quantum system. The first is Markovian feedback, as introduced in quantum optics by Wiseman and Milburn [Phys. Rev. Lett. 70, 548 (1993)]. The second is feedback based on an estimate of the system state, developed recently by Doherty and Jacobs [Phys. Rev. A 60, 2700 (1999)]. Here we choose to call it, for brevity, Bayesian feedback. For systems with nonlinear dynamics, we expect these two methods of feedback control to give markedly different results. The simplest possible nonlinear system is a driven and damped two-level atom, so we choose this as our model system. The monitoring is taken to be homodyne detection of the atomic fluorescence, and the control is by modulating the driving. The aim of the feedback in both cases is to stabilize the internal state of the atom as close as possible to an arbitrarily chosen pure state, in the presence of inefficient detection and other forms of decoherence. Our results (obtained without recourse to stochastic simulations) prove that Bayesian feedback is never inferior, and is usually superior, to Markovian feedback. However, it would be far more difficult to implement than Markovian feedback and it loses its superiority when obvious simplifying approximations are made. It is thus not clear which form of feedback would be better in the face of inevitable experimental imperfections.

Orthographic/phonological facilitation of naming responses in the picture-word task: An event-related fMRI study using overt vocal responding

In the picture-word interference task, naming responses are facilitated when a distractor word is orthographically and phonologically related to the depicted object as compared to an unrelated word. We used event-related functional magnetic resonance imaging (fMRI) to investigate the cerebral hemodynamic responses associated with this priming effect. Serial (or independent-stage) and interactive models of word production that explicitly account for picture-word interference effects assume that the locus of the effect is at the level of retrieving phonological codes, a role attributed recently to the left posterior superior temporal cortex (Wernicke's area). This assumption was tested by randomly presenting participants with trials from orthographically related and unrelated distractor conditions and acquiring image volumes coincident with the estimated peak hemodynamic response for each trial. Overt naming responses occurred in the absence of scanner noise, allowing reaction time data to be recorded. Analysis of this data confirmed the priming effect. Analysis of the fMRI data revealed blood oxygen level-dependent signal decreases in Wernicke's area and the right anterior temporal cortex, whereas signal increases were observed in the anterior cingulate, the right orbitomedial prefrontal, somatosensory, and inferior parietal cortices, and the occipital lobe. The results are interpreted as supporting the locus for the facilitation effect as assumed by both classes of theoretical model of word production. In addition, our results raise the possibilities that, counterintuitively, picture-word interference might be increased by the presentation of orthographically related distractors, due to competition introduced by activation of phonologically related word forms, and that this competition requires inhibitory processes to be resolved. The priming effect is therefore viewed as being sufficient to offset the increased interference. We conclude that information from functional imaging studies might be useful for constraining theoretical models of word production. (C) 2002 Elsevier Science (USA).

Association of hypertension and hypokalemia with Cushing's syndrome caused by ectopic ACTH secretion: a series of 58 cases.

Cushing's syndrome is associated with hypertension in approximately 80% of cases. Hypertension contributes to the marked increased mortality risk of past or current Cushing's syndrome, largely because of increased cardiovascular risk. Observation of the pathophysiological effect of chronically elevated ACTH and cortisol values in patients with ectopic ACTH secretion complements the available data from acute studies of the effects of ACTH and glucocorticoid infusions in normal volunteers. In a retrospective case review, we identified 58 patients with Cushing's syndrome caused by ectopic ACTH secretion, who were treated at the National Institutes of Health between 1983-1997. The diagnosis of an ectopic ACTH cause was confirmed by inferior petrosal sinus sampling and/or pathologic examination of tumor. The commonest causes were bronchial carcinoid (40%) and thymic carcinoid (10%), but 18 of 58 (31%) patients had an unknown source of ectopic ACTH. Hypertension (systolic blood pressure >140 mmHg and/or diastolic blood pressure >90 mmHg in adults) was noted in 45 of 58 (78%) ectopic Cushing's patients, a prevalence similar to that noted in other endogenous Cushing's syndrome etiologies. Hypertension was severe, deemed to require 3 or more drugs by the treating physicians, in 26 of 58 (45%) patients. Hypokalemia was much more prevalent than in patients with other causes of Cushing's syndrome, affecting 33 of 58 (57%) patients. The range of plasma ACTH (17-1557 pg/mL, normal

The distribution and morphological characteristics of serotonergic cells in the brain of monotremes

The distribution and cellular morphology of serotonergic neurons in the brain of two species of monotremes are described. Three clusters of serotonergic neurons were found: a hypothalamic cluster, a cluster in the rostral brainstem and a cluster in the caudal brainstem. Those in the hypothalamus consisted of two groups, the periventricular hypothalamic organ and the infundibular recess, that were intimately associated with the ependymal wall of the third ventricle. Within the rostral brainstem cluster, three distinct divisions were found: the dorsal raphe nucleus (with four subdivisions), the median raphe nucleus and the cells of the supralemniscal region. The dorsal raphe was within and adjacent to the periaqueductal gray matter, the median raphe was associated with the midline ventral to the dorsal raphe, and the cells of the supralemniscal region were in the tegmentum lateral to the median raphe and ventral to the dorsal raphe. The caudal cluster consisted of three divisions: the raphe obscurus nucleus, the raphe pallidus nucleus and the raphe magnus nucleus. The raphe obscurus nucleus was associated with the dorsal midline at the caudal-most part of the medulla oblongata. The raphe pallidus nucleus was found at the ventral midline of the medulla around the inferior olive. Raphe magnus was associated with the midline of the medulla and was found rostral to both the raphe obscurus and raphe pallidus. The results of our study are compared in an evolutionary context with those reported for other mammals and reptiles. Copyright (C) 2002 S. Karger AG, Basel.

A foliar rating system for comparing the resistance of banana cultivars grown as tissue-cultured plantlets in the laboratory to Fusarium wilt

A foliar rating system was developed to assess the progress of Fusarium wilt ( Panama disease) caused by Fusarium oxysporum f. sp. cubense in seven banana cultivars differing in their resistance to race 1 of the pathogen. Plantlets were transplanted into unamended soil naturally infested with the pathogen, soil amended with urea and soil amended with aged chicken manure. A corm invasion score was also developed to assess the accuracy of the foliar symptom score as an indicator of cultivar resistance. On the basis of foliar symptom scores alone, the response of five of the seven cultivars in the chicken manure treatment corresponded to their known field response. However, the response of the other two cultivars, both susceptible to the pathogen in the field, fell into two categories. One had a high foliar symptom score and a correspondingly high corm invasion score, whereas the other had a low foliar symptom score and a high corm invasion score. Breeders need to be aware of the two categories of susceptible response, if inferior breeding material is to be rejected early on in a breeding program.

Modeling diffraction in free-space optical interconnects by the mode expansion method

Free-space optical interconnects (FSOIs), made up of dense arrays of vertical-cavity surface-emitting lasers, photodetectors and microlenses can be used for implementing high-speed and high-density communication links, and hence replace the inferior electrical interconnects. A major concern in the design of FSOIs is minimization of the optical channel cross talk arising from laser beam diffraction. In this article we introduce modifications to the mode expansion method of Tanaka et al. [IEEE Trans. Microwave Theory Tech. MTT-20, 749 (1972)] to make it an efficient tool for modelling and design of FSOIs in the presence of diffraction. We demonstrate that our modified mode expansion method has accuracy similar to the exact solution of the Huygens-Kirchhoff diffraction integral in cases of both weak and strong beam clipping, and that it is much more accurate than the existing approximations. The strength of the method is twofold: first, it is applicable in the region of pronounced diffraction (strong beam clipping) where all other approximations fail and, second, unlike the exact-solution method, it can be efficiently used for modelling diffraction on multiple apertures. These features make the mode expansion method useful for design and optimization of free-space architectures containing multiple optical elements inclusive of optical interconnects and optical clock distribution systems. (C) 2003 Optical Society of America.

Cortex, cognition and the cell: New insights into the pyramidal neuron and prefrontal function

Arguably the most complex conical functions are seated in human cognition, the how and why of which have been debated for centuries by theologians, philosophers and scientists alike. In his best-selling book, An Astonishing Hypothesis: A Scientific Search for the Soul, Francis Crick refined the view that these qualities are determined solely by cortical cells and circuitry. Put simply, cognition is nothing more, or less, than a biological function. Accepting this to be the case, it should be possible to identify the mechanisms that subserve cognitive processing. Since the pioneering studies of Lorent de No and Hebb, and the more recent studies of Fuster, Miller and Goldman-Rakic, to mention but a few, much attention has been focused on the role of persistent neural activity in cognitive processes. Application of modern technologies and modelling techniques has led to new hypotheses about the mechanisms of persistent activity. Here I focus on how regional variations in the pyramidal cell phenotype may determine the complexity of cortical circuitry and, in turn, influence neural activity. Data obtained from thousands of individually injected pyramidal cells in sensory, motor, association and executive cortex reveal marked differences in the numbers of putative excitatory inputs received by these cells. Pyramidal cells in prefrontal cortex have, on average, up to 23 times more dendritic spines than those in the primary visual area. I propose that without these specializations in the structure of pyramidal cells, and the circuits they form, human cognitive processing would not have evolved to its present state. I also present data from both New World and Old World monkeys that show varying degrees of complexity in the pyramidal cell phenotype in their prefrontal cortices, suggesting that cortical circuitry and, thus, cognitive styles are evolving independently in different species.

Sensitivity of Helicoverpa armigera nucleopolyhedrovirus polyhedra to sodium dodecyl sulfate

Sodium dodecyl sulfate (SDS) is commonly used to extract polyhedra from infected cells and diseased dead larval tissues. It was found, however, that 80% of Helicoverpa armigera nucleopolyhedrovirus (HaSNPV) polyhedra produced via cell culture were damaged after 30 min of 0.5% SDS treatment whereas only 20% of in vivo produced polyhedra were damaged by the same treatment. Transmission and scanning electron microscopy revealed that the damaged polyhedra had lost their polyhedron envelopes and virions were dislodged from the polyhedrin matrix, leaving empty spaces that were previously occupied by the occluded virions. Up to 20% in vitro produced polyhedra were resistant to SDS and remained intact, even after a 24 h exposure to SDS. This sensitivity to SDS was observed across a range of cell culture media, including serum supplemented media. Electron microscopy also revealed that the inferior polyhedron envelope of in vitro produced polyhedra is likely due to poor interaction between the polyhedron envelope, polyhedron envelope protein (PEP), and polyhedrin matrix. The PEP gene was cloned and sequenced and mutations in this gene were ruled out as an explanation. In vitro produced polyhedra that were passed through insect larva once were resistant to SDS, indicating that a critical component is lacking in insect cell culture medium used for producing HaSNPV or the cells growing in culture are inefficient in some ways in relation to production of polyhedra. (C) 2002 Elsevier Science (USA). All rights reserved.

Cart??o do cidad??o

O pagamento dos benef??cios sociais, efetuado no guich?? de caixa das ag??ncias, era um processo lento e oneroso ao cidad??o e ?? CAIXA. Envolvia elevado quantitativo de atendentes e significativo tempo para a execu????o de rotinas inerentes, principalmente no que diz respeito ?? qualifica????o e ?? identifica????o do trabalhador, ao tratamento da documenta????o e ?? coleta de assinatura no documento de pagamento, gerando elevado custo operacional. Em 1995, a CAIXA lan??ou o Cart??o do Trabalhador, que permitia o acompanhamento de lan??amentos do Fundo de Garantia do Tempo de Servi??o (FGTS) e acesso ao saldo de cotas de sua participa????o no Programa de Integra????o Social (PIS), mas n??o tinha a funcionalidade de saque de benef??cios e n??o atendia os benefici??rios do Abono Salarial e do Seguro- Desemprego. A necessidade de aperfei??oar e integrar os processos de atendimento e pagamento desses produtos sociais levou ?? cria????o do Cart??o do Cidad??o, que proporcionou melhoria significativa na qualidade do atendimento ao cidad??o e minimizou os custos operacionais

Valores e decis??es dif??ceis

Logo no in??cio do caso, o leitor ?? colocado no papel de membro de um conselho respons??vel por uma ag??ncia rural de sa??de (??rg??o da realidade p??blica canadense) com um grande d??ficit or??ament??rio. Cabe ao conselho examinar a proposta de or??amento para o pr??ximo ano fiscal, levando em considera????o uma s??rie de fatores importantes para a adequada presta????o de servi??os de sa??de para a regi??o. O caso apresenta um hist??rico dos servi??os prestados pela ag??ncia, vis??o e valores do ??rg??o, servi??os prestados, desafios, detalhes or??ament??rios, demandas p??blicas e contexto pol??tico. Ao final, o leitor ?? incitado a tomar decis??es referentes a cortes no or??amento. O caso presta-se ao ensino de temas como gest??o or??ament??ria, planejamento e processo decis??rio

Economicidade do projeto de amplia????o do aeroporto de Guarulhos

O objetivo deste trabalho foi o de propor alternativas para orientar a solu????o ao atendimento da demanda do aeroporto de Guarulhos de forma a reduzir os custos (de investimento e operacionais) or??ados, prazo de implanta????o do projeto e tamb??m o de melhorar a qualidade do projeto, de modo que a opera????o do aeroporto se tornasse a mais otimizada poss??vel. O projeto de amplia????o do aeroporto de Guarulhos, conhecido como projeto do Terminal de Passageiros-3 (TPS-3) era, e ainda ??, o maior da carteira de investimentos da INFRAERO. Outro assim, ele se encontrava com o Projeto B??sico encerrado em meados de 2000, fase bastante adequada para o in??cio de um processo de otimiza????o. Em paralelo, h?? nos ??rg??os centrais do Governo Federal, em especial no Minist??rio do Planejamento, Or??amento e Gest??o, uma tentativa de se implantar nos projetos governamentais ferramentas de gest??o que possibilitem avaliar, por exemplo, a real necessidade das obras, a funcionalidade do projeto e a otimiza????o econ??mica dos mesmos

A experi??ncia da Escola Nacional de Administra????o P??blica na articula????o de redes de capacita????o

Este artigo relata algumas das experi??ncias da ENAP como membro, articuladora e incentivadora da atua????o em rede entre institui????es voltadas ?? forma????o e ?? capacita????o de servidores p??blicos. ?? dado destaque ?? an??lise da experi??ncia da Rede Descentralizada de Capacita????o de gestores sociais, vivenciada em parceria com o Minist??rio do Desenvolvimento Social, no per??odo de 2007 e 2008. Ao final s??o apresentadas algumas contribui????es ?? reflex??o sobre os resultados dessas iniciativas.

Educa????o do campo no Estado de S??o Paulo: an??lise do n??vel de ruralidade das escolas no desempenho escolar

Este trabalho tem como objetivo central analisar a influ??ncia da localiza????o da escola e da origem dos alunos (rural e urbano) na taxa de evas??o, na taxa de aprova????o/reprova????o, no desempenho obtido no Ideb e na Prova Brasil. Para tanto, foram considerados os alunos do 5?? ano (quarta s??rie) do ensino fundamental das redes municipais e estaduais do Estado de S??o Paulo. A tipologia do IBGE para classifica????o das escolas em rurais e urbanas e o local de moradia dos alunos foram utilizados como forma de caracterizar o n??vel de ruralidade das escolas. O trabalho organiza um diagn??stico das pol??ticas em andamento; aponta algumas diretrizes para o aperfei??oamento das futuras interven????es na ??rea espec??fica de atua????o governamental; e mostra que, em v??rias situa????es, o desempenho das escolas ???rurais???, considerando os itens analisados, ?? inferior ao desempenho das escolas urbanas

Triste e incompleta : uma visão feminina da mulher infértil

Este artigo relata resultados de uma pesquisa que teve como objetivo investigar as representações sociais da infertilidade feminina, entre mulheres de diferentes estratos sociais. Foram entrevistadas 180 mulheres, com idade variando entre 18 e 40 anos, sendo 90 moradoras de bairros populares, e 90 moradoras de dois bairros considerados de classe-média. Cada grupo foi dividido em 3 subgrupos: a) 30 mulheres casadas, com pelo menos um filho biológico; b) 30 mulheres casadas há pelo menos 1 ano, sem filhos; c) 30 mulheres solteiras, sem filhos. Para a coleta de dados utilizou-se a técnica de associação livre, tendo como expressão geradora "mulher que não pode ter filhos", além de perguntas específicas sobre a temática de interesse. Os dados mostraram como principais elementos do campo representacional tristeza, incompleta, frustração, cobrança dos outros, solidão, pessoa inferior, adoção, busca de soluções e não é problema, confirmando a permanência da concepção da infertilidade como uma condição estigmatizante para a mulher.

Crítica à concepção hegemônica de "erradicação da pobreza" : um estudo sobre a estratégia de naturalização e gestão da barbárie no Espírito Santo

Com base em pesquisa bibliográfica e documental, e fazendo uso da análise de conteúdo, este trabalho tem como objetivo geral analisar a meta erradicar a pobreza até 2025, constituinte do Plano de Desenvolvimento Espírito Santo 2025. Compreendemos que essa meta faz parte do modelo de ―desenvolvimento sustentado‖ elaborado pela burguesia capixaba, organizada no Movimento Empresarial Espírito Santo em Ação, e em articulação com o executivo estadual e a Petrobrás, sem que tenha havido participação de trabalhadores na elaboração do Plano mencionado. Seguem-se as principais conclusões. A meta em questão foi construída sob o marco ideopolítico e teórico da ―internacionalização do combate à pobreza‖, transpondo-se para o território estadual o discurso hegemônico de erradicação daquela condição social, entendida como sendo, em última análise, de responsabilidade do indivíduo, e não enquanto consequência direta do modo de produção capitalista. Além disso, os pobres são compreendidos, na elaboração da meta, de forma dual: ora identificados através do ―pressuposto da falta‖, ora enquanto ―agentes‖ livres para construir seu próprio futuro. Em consequência dessa dualidade, são propostas duas vias de ação tidas como essenciais para ―erradicar a pobreza‖: uma, centrada na transferência de renda para os que vivem na pobreza mais acentuada, e outra, na concessão de (micro)crédito para os pobres não miseráveis, com vistas a possibilitar que se tornem ―empreendedores‖. A meta analisada visa contribuir para promover a ―paz social‖, através da contenção dos pobres e de sua latente revolta diante de sua degradada condição de vida em território espírito-santense, o que demonstra sua funcionalidade para naturalizar e gerir a barbárie que marca a contemporaneidade capitalista.