Comparative analysis of time-frequency methods estimating the time-varying microstructure of sleep EEG spindles

Proceedings of the Information Technology Applications in Biomedicine, Ioannina - Epirus, Greece, October 26-28, 2006

Potential dementia biomarkers based on the time-varying microstructure of sleep EEG spindles

Proceedings of the 29th Annual International Conference of the IEEE EMBS Cité Internationale, Lyon, France August 23-26, 2007

Personalised Advertising Supported by Agents

This paper reports the development of a B2B platform for the personalization of the publicity transmitted during the program intervals. The platform as a whole must ensure that the intervals are filled with ads compatible with the profile, context and expressed interests of the viewers. The platform acts as an electronic marketplace for advertising agencies (content producer companies) and multimedia content providers (content distribution companies). The companies, once registered at the platform, are represented by agents who negotiate automatically the price of the interval timeslots according to the specified price range and adaptation behaviour. The candidate ads for a given viewer interval are selected through a matching mechanism between ad, viewer and the current context (program being watched) profiles. The overall architecture of the platform consists of a multiagent system organized into three layers consisting of: (i) interface agents that interact with companies; (ii) enterprise agents that model the companies, and (iii) delegate agents that negotiate a specific ad or interval. The negotiation follows a variant of the Iterated Contract Net Interaction Protocol (ICNIP) and is based on the price/s offered by the advertising agencies to occupy the viewer’s interval.

A MOSFET-only wideband LNA exploiting thermal noise canceling and gain optimization

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores

Optimização na adequação turbina-compressor numa turbina agás

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica

A questão visual na oftalmologia pediátrica da região de Lisboa

RESUMO: Na parte inicial incluem-se algumas notas sucintas com base no panorama científico,histórico e cultural da visão considerada segundo três abordagens - o olho (o olho humano na especificidade da sua posição filogenética, elemento anátomo-funcional básico do sistema visual ao qual o cérebro pertence), os olhos (unidades gémeas essenciais do rosto na sua actividade consensual e conjugada da binocularidade), o olhar (carregado de expressão psicológica e o seu efeito sobre o observador, sinal para o comportamento e criador de sentimentos, sedimentado em obras de arte e em formas de superstição dos povos). Segue-se a apresentação de um estudo descritivo transversal, como contribuição para o conhecimento do estado de saúde visual da população infantil da região de Lisboa e determinar factores que o influenciam. Entre Outubro de 2005 e Agosto de 2006 examinaram-se 649 crianças com idade inferior a 10 anos da Consulta de Oftalmologia Pediátrica dos Serviços de Assistência Médico-Social do Sindicato dos Bancários do Sul e Ilhas (SAMS). Colheram-se dados respeitantes a mais de 250 variáveis primárias que cobriram a maior parte dos itens do exame oftalmológico habitual. Na análise dos dados teve-se especialmente em conta a idade, com um papel decisivo nas principais fases de desenvolvimento do sistema visual. No caso das crianças de 6 a 7 anos de idade põem-se lado a lado resultados dos SAMS e das Escolas. A profusão de dados numéricos ditou a necessidade da determinação frequente da significância estatística dos resultados de subgrupos. Alguns resultados do estudo, na sua maioria do grupo SAMS: Crianças de 6-7 anos, 71,1% (SAMS) e 91,5% (Escolas) não tinham sido examinadas com menos de 4 anos. Frequência global de alterações miópicas 9,4%, de alterações hipermetrópicas 25,3%, umas e outras com variações acentuadas com a idade. Estrabismo convergente 3,9%. Ambliopia 2,6% (13/491 crianças >=4 anos de idade), mais frequente no sexo feminino, naquelas que tiveram a sua 1ª observação depois dos 4 anos e em que os pais não aderiam à terapêutica prescrita. Objectivos específicos ocuparam-se da acuidade visual e da refracção ocular. O estudo comparativo da refractometria automática sem e com cicloplegia permitiu evidenciar que o teste da acuidade visual é insuficiente, por si só, para fazer o diagnóstico correcto. A análise dos antecedentes familiares oftalmológicos demonstrou a importância do seu conhecimento e pôs em evidência, entre outras, as seguintes relações: 10 pag1.qxp 27-11-2001 18:28 Page 10 Índice Geral 11 Crianças com antecedentes de alterações miópicas têm maior frequência de diagnóstico de alterações miópicas e de refracção negativa, uma taxa mais elevada de correspondência quantitativa diagnóstico/refracção nas alterações miópicas. Estas crianças também têm, em geral, características inversas no que diz respeito a alterações hipermetrópicas. Crianças com antecedentes de alterações hipermetrópicas têm maior frequência de diagnóstico de alterações hipermetrópicas. Crianças com antecedentes de estrabismo têm maior frequência de diagnóstico de estrabismo convergente manifesto e de esodesvios no seu todo. Crianças com antecedentes familiares de astigmatismo têm maior frequência de diagnóstico de astigmatismo. Traçam-se alguns perfis oftalmológicos infantis que permitem apreciar de forma sinóptica um conjunto de parâmetros da saúde da visão. Os dados colhidos sobre a aderência dos pais à terapêutica prescrita e sobre a atitude em relação ao uso de óculos assim como os dados sobre o comportamento da criança na sala de aula e dificuldades de aprendizagem foram em geral escassos para permitirem tirar conclusões, embora mostrem indícios a investigar futuramente. Paralelamente ortoptistas e enfermeiras efectuaram um rastreio escolar da acuidade visual <0,8 e de alterações da motilidade ocular extrínseca que abrangeu 520 alunos do 1º ano do 1º ciclo do ensino básico (2005/2006) das escolas públicas da cidade de Lisboa. 101 destas crianças foram observadas no consultório da autora, umas referidas a partir do rastreio, outras como controlo deste. Quanto à acuidade visual o valor preditivo do teste negativo foi de 91% mas o do teste positivo de apenas 67% (33% de falsos positivos, consequentemente uma alta taxa de sobrerreferenciação). A qualidade do rastreio efectuado por ortoptistas foi inferior à do efectuado por enfermeiras. O rastreio não teve qualidade aceitável. Foi feito um inquérito a médicos e enfermeiros de centros de saúde sobre conhecimentos, atitudes e práticas em relação com os cuidados de oftalmologia pediátrica. Discutem-se os resultados, tiram-se conclusões e fazem-se recomendações susceptíveis de contribuir para uma melhor saúde visual das crianças. ABSTRACT: Firstly some brief remarks are made based on the scientific, historical and cultural panorama of the human vision with regard to three approaches: the eye (the human eye in its specific filogenetic place, fundamental anatomofunctional element of the visual system in interaction with the brain), the eyes (essential twin units of the face with their consensual and conjugated binocular activity), the gaze (psychologicaly overloaded, a means to express oneself and to influence the observer, a guide to other persons' behaviour, consolidated in works of art and in people's traditional superstitious believes and ways of thinking). A report is made on a cross-sectional descriptive study whose goal is to contribute to the knowledge of the level of visual health of children in the Lisbon Region and to identify factors which determine it. Between October 2005 and August 2006 649 children under 10 years were observed at the pediatric ophthalmologic consultation in the SAMS (Serviços de Assistência Médico-Social do Sindicato dos Bancários do Sul e Ilhas). Data were collected concerning more than 250 primary variables covering most itens of the usual ophthalmological examination. Special attention was paid to children's age since it plays a crucial role in main stages of visual system development. In the case of children age 6 to 7 SAMS and school results are often put side by side. On account of the great number of numerical data it was often necessary to look at the degree of statistical significancy of differencies between subgroups. Some of the study's results (mostly SAMS): Children age 6 to 7 - 71,1% (SAMS) and 91,5% (Schools) had not an ophthalmologic examination before 4 years old. Total frequency of myopic disorders 9,4%, of hypermetropic disorders 25,3%, both showing great differences between age groups; convergent strabismus 3,9%; amblyopia 2,6% (13/491 children over 3 years old), more frequent among little girls, in those with 1st examination after 4 years old and in those whose parents didn´t complied to the therapy ordered for the child. Specific objectives dealt with visual acuity and ocular refraction. The comparison of automatic refractometry without and with cycloplegy showed that visual acuity testing is often not enough for a correct diagnosis. Eye disorders in the family history proved to be a very important information. Analysis of corresponding data disclosed a lot of relationships among others: 12 pag1.qxp 27-11-2001 18:28 Page 12 Índice Geral 13 Children with a family history of myopic disorders have more frequently a diagnosis of myopic disorders and a negative refraction, a higher rate of quantitative diagnosis/refraction matching concerning myopic disorders. Those children have in general inverse characteristics regarding hypermetropic disorders. Children with a family history of hypermetropic disorders have more frequently a diagnosis of hypermetropic disorders. Children with a family history of strabismus have more frequently a diagnosis of manifest convergent strabismus and all forms of esodeviations. Children with a family history of astigmatism have more frequently a diagnosis of astigmatism. Ophthalmologic profiles are drawn allowing to take into account in a synoptic way a set of visual health parameters. Data on parents' compliance with therapy ordered for the child, and attitudes regarding child's glass wearing, as well as data on child's behaviour in the classroom and learning difficulties were as a rule too few to allow conclusions but still need more studies in the future. Orthoptists and nurses performed in the same study period a screening of visual acuity <0,8 and of ocular motility disorders addressed to children of 1srt degree of public schools (term 2005/2006) in the town of Lisbon. 520 of such children were screened. 101 of them were examined by the author in her medical office; some were refered, the others taken as a control. Regarding visual acuity the predictive value of a negative test was 91% but the predictive value of a positive test was only 67% (33% of false positive results, consequently a too high rate of overreferal). Performed by orthoptists screening quality was inferior in comparison with screening done by nurses. On the whole this screening had not the required quality. A survey on physicians' and nurses' knowledge, attitudes and practices related to pediatric ophthalmologic care was carried out in health centers. Results are discussed, conclusions drawn. Some suggestions are made aiming at a better children's visual health.

Estrutura a partir do Movimento em Sistemas Autónomos

Mestrado em Engenharia Electrotécnica e de Computadores - Ramo de Sistemas Autónomos

Static detection of anomalies in transactional memory programs

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do Grau de Mestre em Engenharia Informática

Multiple sequence alignment correction using constraints

Trabalho apresentado no âmbito do European Master in Computational Logics, como requisito parcial para obtenção do grau de Mestre em Computational Logics

Advanced image processing techniques for detection and quantification of drusen

Dissertation presented to obtain the degree of Doctor of Philosophy in Electrical Engineering, speciality on Perceptional Systems, by the Universidade Nova de Lisboa, Faculty of Sciences and Technology

Unmixing hyperspectral data: independent and dependent component analysis

The development of high spatial resolution airborne and spaceborne sensors has improved the capability of ground-based data collection in the fields of agriculture, geography, geology, mineral identification, detection [2, 3], and classification [4–8]. The signal read by the sensor from a given spatial element of resolution and at a given spectral band is a mixing of components originated by the constituent substances, termed endmembers, located at that element of resolution. This chapter addresses hyperspectral unmixing, which is the decomposition of the pixel spectra into a collection of constituent spectra, or spectral signatures, and their corresponding fractional abundances indicating the proportion of each endmember present in the pixel [9, 10]. Depending on the mixing scales at each pixel, the observed mixture is either linear or nonlinear [11, 12]. The linear mixing model holds when the mixing scale is macroscopic [13]. The nonlinear model holds when the mixing scale is microscopic (i.e., intimate mixtures) [14, 15]. The linear model assumes negligible interaction among distinct endmembers [16, 17]. The nonlinear model assumes that incident solar radiation is scattered by the scene through multiple bounces involving several endmembers [18]. Under the linear mixing model and assuming that the number of endmembers and their spectral signatures are known, hyperspectral unmixing is a linear problem, which can be addressed, for example, under the maximum likelihood setup [19], the constrained least-squares approach [20], the spectral signature matching [21], the spectral angle mapper [22], and the subspace projection methods [20, 23, 24]. Orthogonal subspace projection [23] reduces the data dimensionality, suppresses undesired spectral signatures, and detects the presence of a spectral signature of interest. The basic concept is to project each pixel onto a subspace that is orthogonal to the undesired signatures. As shown in Settle [19], the orthogonal subspace projection technique is equivalent to the maximum likelihood estimator. This projection technique was extended by three unconstrained least-squares approaches [24] (signature space orthogonal projection, oblique subspace projection, target signature space orthogonal projection). Other works using maximum a posteriori probability (MAP) framework [25] and projection pursuit [26, 27] have also been applied to hyperspectral data. In most cases the number of endmembers and their signatures are not known. Independent component analysis (ICA) is an unsupervised source separation process that has been applied with success to blind source separation, to feature extraction, and to unsupervised recognition [28, 29]. ICA consists in finding a linear decomposition of observed data yielding statistically independent components. Given that hyperspectral data are, in given circumstances, linear mixtures, ICA comes to mind as a possible tool to unmix this class of data. In fact, the application of ICA to hyperspectral data has been proposed in reference 30, where endmember signatures are treated as sources and the mixing matrix is composed by the abundance fractions, and in references 9, 25, and 31–38, where sources are the abundance fractions of each endmember. In the first approach, we face two problems: (1) The number of samples are limited to the number of channels and (2) the process of pixel selection, playing the role of mixed sources, is not straightforward. In the second approach, ICA is based on the assumption of mutually independent sources, which is not the case of hyperspectral data, since the sum of the abundance fractions is constant, implying dependence among abundances. This dependence compromises ICA applicability to hyperspectral images. In addition, hyperspectral data are immersed in noise, which degrades the ICA performance. IFA [39] was introduced as a method for recovering independent hidden sources from their observed noisy mixtures. IFA implements two steps. First, source densities and noise covariance are estimated from the observed data by maximum likelihood. Second, sources are reconstructed by an optimal nonlinear estimator. Although IFA is a well-suited technique to unmix independent sources under noisy observations, the dependence among abundance fractions in hyperspectral imagery compromises, as in the ICA case, the IFA performance. Considering the linear mixing model, hyperspectral observations are in a simplex whose vertices correspond to the endmembers. Several approaches [40–43] have exploited this geometric feature of hyperspectral mixtures [42]. Minimum volume transform (MVT) algorithm [43] determines the simplex of minimum volume containing the data. The MVT-type approaches are complex from the computational point of view. Usually, these algorithms first find the convex hull defined by the observed data and then fit a minimum volume simplex to it. Aiming at a lower computational complexity, some algorithms such as the vertex component analysis (VCA) [44], the pixel purity index (PPI) [42], and the N-FINDR [45] still find the minimum volume simplex containing the data cloud, but they assume the presence in the data of at least one pure pixel of each endmember. This is a strong requisite that may not hold in some data sets. In any case, these algorithms find the set of most pure pixels in the data. Hyperspectral sensors collects spatial images over many narrow contiguous bands, yielding large amounts of data. For this reason, very often, the processing of hyperspectral data, included unmixing, is preceded by a dimensionality reduction step to reduce computational complexity and to improve the signal-to-noise ratio (SNR). Principal component analysis (PCA) [46], maximum noise fraction (MNF) [47], and singular value decomposition (SVD) [48] are three well-known projection techniques widely used in remote sensing in general and in unmixing in particular. The newly introduced method [49] exploits the structure of hyperspectral mixtures, namely the fact that spectral vectors are nonnegative. The computational complexity associated with these techniques is an obstacle to real-time implementations. To overcome this problem, band selection [50] and non-statistical [51] algorithms have been introduced. This chapter addresses hyperspectral data source dependence and its impact on ICA and IFA performances. The study consider simulated and real data and is based on mutual information minimization. Hyperspectral observations are described by a generative model. This model takes into account the degradation mechanisms normally found in hyperspectral applications—namely, signature variability [52–54], abundance constraints, topography modulation, and system noise. The computation of mutual information is based on fitting mixtures of Gaussians (MOG) to data. The MOG parameters (number of components, means, covariances, and weights) are inferred using the minimum description length (MDL) based algorithm [55]. We study the behavior of the mutual information as a function of the unmixing matrix. The conclusion is that the unmixing matrix minimizing the mutual information might be very far from the true one. Nevertheless, some abundance fractions might be well separated, mainly in the presence of strong signature variability, a large number of endmembers, and high SNR. We end this chapter by sketching a new methodology to blindly unmix hyperspectral data, where abundance fractions are modeled as a mixture of Dirichlet sources. This model enforces positivity and constant sum sources (full additivity) constraints. The mixing matrix is inferred by an expectation-maximization (EM)-type algorithm. This approach is in the vein of references 39 and 56, replacing independent sources represented by MOG with mixture of Dirichlet sources. Compared with the geometric-based approaches, the advantage of this model is that there is no need to have pure pixels in the observations. The chapter is organized as follows. Section 6.2 presents a spectral radiance model and formulates the spectral unmixing as a linear problem accounting for abundance constraints, signature variability, topography modulation, and system noise. Section 6.3 presents a brief resume of ICA and IFA algorithms. Section 6.4 illustrates the performance of IFA and of some well-known ICA algorithms with experimental data. Section 6.5 studies the ICA and IFA limitations in unmixing hyperspectral data. Section 6.6 presents results of ICA based on real data. Section 6.7 describes the new blind unmixing scheme and some illustrative examples. Section 6.8 concludes with some remarks.

Vertex component analysis: a geometric-based approach to unmix hyperspectral data

Hyperspectral remote sensing exploits the electromagnetic scattering patterns of the different materials at specific wavelengths [2, 3]. Hyperspectral sensors have been developed to sample the scattered portion of the electromagnetic spectrum extending from the visible region through the near-infrared and mid-infrared, in hundreds of narrow contiguous bands [4, 5]. The number and variety of potential civilian and military applications of hyperspectral remote sensing is enormous [6, 7]. Very often, the resolution cell corresponding to a single pixel in an image contains several substances (endmembers) [4]. In this situation, the scattered energy is a mixing of the endmember spectra. A challenging task underlying many hyperspectral imagery applications is then decomposing a mixed pixel into a collection of reflectance spectra, called endmember signatures, and the corresponding abundance fractions [8–10]. Depending on the mixing scales at each pixel, the observed mixture is either linear or nonlinear [11, 12]. Linear mixing model holds approximately when the mixing scale is macroscopic [13] and there is negligible interaction among distinct endmembers [3, 14]. If, however, the mixing scale is microscopic (or intimate mixtures) [15, 16] and the incident solar radiation is scattered by the scene through multiple bounces involving several endmembers [17], the linear model is no longer accurate. Linear spectral unmixing has been intensively researched in the last years [9, 10, 12, 18–21]. It considers that a mixed pixel is a linear combination of endmember signatures weighted by the correspondent abundance fractions. Under this model, and assuming that the number of substances and their reflectance spectra are known, hyperspectral unmixing is a linear problem for which many solutions have been proposed (e.g., maximum likelihood estimation [8], spectral signature matching [22], spectral angle mapper [23], subspace projection methods [24,25], and constrained least squares [26]). In most cases, the number of substances and their reflectances are not known and, then, hyperspectral unmixing falls into the class of blind source separation problems [27]. Independent component analysis (ICA) has recently been proposed as a tool to blindly unmix hyperspectral data [28–31]. ICA is based on the assumption of mutually independent sources (abundance fractions), which is not the case of hyperspectral data, since the sum of abundance fractions is constant, implying statistical dependence among them. This dependence compromises ICA applicability to hyperspectral images as shown in Refs. [21, 32]. In fact, ICA finds the endmember signatures by multiplying the spectral vectors with an unmixing matrix, which minimizes the mutual information among sources. If sources are independent, ICA provides the correct unmixing, since the minimum of the mutual information is obtained only when sources are independent. This is no longer true for dependent abundance fractions. Nevertheless, some endmembers may be approximately unmixed. These aspects are addressed in Ref. [33]. Under the linear mixing model, the observations from a scene are in a simplex whose vertices correspond to the endmembers. Several approaches [34–36] have exploited this geometric feature of hyperspectral mixtures [35]. Minimum volume transform (MVT) algorithm [36] determines the simplex of minimum volume containing the data. The method presented in Ref. [37] is also of MVT type but, by introducing the notion of bundles, it takes into account the endmember variability usually present in hyperspectral mixtures. The MVT type approaches are complex from the computational point of view. Usually, these algorithms find in the first place the convex hull defined by the observed data and then fit a minimum volume simplex to it. For example, the gift wrapping algorithm [38] computes the convex hull of n data points in a d-dimensional space with a computational complexity of O(nbd=2cþ1), where bxc is the highest integer lower or equal than x and n is the number of samples. The complexity of the method presented in Ref. [37] is even higher, since the temperature of the simulated annealing algorithm used shall follow a log( ) law [39] to assure convergence (in probability) to the desired solution. Aiming at a lower computational complexity, some algorithms such as the pixel purity index (PPI) [35] and the N-FINDR [40] still find the minimum volume simplex containing the data cloud, but they assume the presence of at least one pure pixel of each endmember in the data. This is a strong requisite that may not hold in some data sets. In any case, these algorithms find the set of most pure pixels in the data. PPI algorithm uses the minimum noise fraction (MNF) [41] as a preprocessing step to reduce dimensionality and to improve the signal-to-noise ratio (SNR). The algorithm then projects every spectral vector onto skewers (large number of random vectors) [35, 42,43]. The points corresponding to extremes, for each skewer direction, are stored. A cumulative account records the number of times each pixel (i.e., a given spectral vector) is found to be an extreme. The pixels with the highest scores are the purest ones. N-FINDR algorithm [40] is based on the fact that in p spectral dimensions, the p-volume defined by a simplex formed by the purest pixels is larger than any other volume defined by any other combination of pixels. This algorithm finds the set of pixels defining the largest volume by inflating a simplex inside the data. ORA SIS [44, 45] is a hyperspectral framework developed by the U.S. Naval Research Laboratory consisting of several algorithms organized in six modules: exemplar selector, adaptative learner, demixer, knowledge base or spectral library, and spatial postrocessor. The first step consists in flat-fielding the spectra. Next, the exemplar selection module is used to select spectral vectors that best represent the smaller convex cone containing the data. The other pixels are rejected when the spectral angle distance (SAD) is less than a given thresh old. The procedure finds the basis for a subspace of a lower dimension using a modified Gram–Schmidt orthogonalizati on. The selected vectors are then projected onto this subspace and a simplex is found by an MV T pro cess. ORA SIS is oriented to real-time target detection from uncrewed air vehicles using hyperspectral data [46]. In this chapter we develop a new algorithm to unmix linear mixtures of endmember spectra. First, the algorithm determines the number of endmembers and the signal subspace using a newly developed concept [47, 48]. Second, the algorithm extracts the most pure pixels present in the data. Unlike other methods, this algorithm is completely automatic and unsupervised. To estimate the number of endmembers and the signal subspace in hyperspectral linear mixtures, the proposed scheme begins by estimating sign al and noise correlation matrices. The latter is based on multiple regression theory. The signal subspace is then identified by selectin g the set of signal eigenvalue s that best represents the data, in the least-square sense [48,49 ], we note, however, that VCA works with projected and with unprojected data. The extraction of the end members exploits two facts: (1) the endmembers are the vertices of a simplex and (2) the affine transformation of a simplex is also a simplex. As PPI and N-FIND R algorithms, VCA also assumes the presence of pure pixels in the data. The algorithm iteratively projects data on to a direction orthogonal to the subspace spanned by the endmembers already determined. The new end member signature corresponds to the extreme of the projection. The algorithm iterates until all end members are exhausted. VCA performs much better than PPI and better than or comparable to N-FI NDR; yet it has a computational complexity between on e and two orders of magnitude lower than N-FINDR. The chapter is structure d as follows. Section 19.2 describes the fundamentals of the proposed method. Section 19.3 and Section 19.4 evaluate the proposed algorithm using simulated and real data, respectively. Section 19.5 presents some concluding remarks.

Sistema localizador interior de baixo custo

Projeto para obtenção do grau de Mestre em Engenharia Informática e de Computadores

Burrows-wheeler transform in secondary memory

Master’s Thesis in Computer Engineering

Salmonella enterica subsp houtenae serogroup O:16 in a HIV positive patient: case report

We described a case of salmonellosis in a 33-year old HIV-infected patient. The patient presented oral and esophageal candidiasis, intense epigastric and retrosternal pain. During the physical examination he was hypochloraemic, acyanotic, hypohydrated, anicteric and afebrile. Admittance laboratorial tests indicated: red cells 3.6 millions/mm³; hemoglobin, 10.1 g/dL; leukocyte count, 3,000/mm³, with 1% of eosinophils, 14% of non-segmented and 53% of segmented neutrophils and 31% of lymphocytes. The blood culture was positive for Salmonella enterica subsp houtenae serogroup O:16. This is probably the first human report of bacteremia due to Salmonella enterica subsp houtenae in Brazil associated to HIV-infected patient.