Theoretical Analysis of Multimodal Four-Wave Mixing in Optical Microwires

Optical fiber microwires (OFMs) are nonlinear optical waveguides that support several spatial modes. The multimodal generalized nonlinear Schrodinger equation (MM-GNLSE) is deduced taking into account the linear and nonlinear modal coupling. A detailed theoretical description of four-wave mixing (FWM) considering the modal coupling is developed. Both, the intramode and the intermode phase-matching conditions is calculated for an optical microwire in a strong guiding regime. Finally, the FWM dynamics is studied and the amplitude evolution of the pump beams, the signal and the idler are analyzed.

Classification and staging of chronic liver disease from multimodal data

Chronic liver disease (CLD) is most of the time an asymptomatic, progressive, and ultimately potentially fatal disease. In this study, an automatic hierarchical procedure to stage CLD using ultrasound images, laboratory tests, and clinical records are described. The first stage of the proposed method, called clinical based classifier (CBC), discriminates healthy from pathologic conditions. When nonhealthy conditions are detected, the method refines the results in three exclusive pathologies in a hierarchical basis: 1) chronic hepatitis; 2) compensated cirrhosis; and 3) decompensated cirrhosis. The features used as well as the classifiers (Bayes, Parzen, support vector machine, and k-nearest neighbor) are optimally selected for each stage. A large multimodal feature database was specifically built for this study containing 30 chronic hepatitis cases, 34 compensated cirrhosis cases, and 36 decompensated cirrhosis cases, all validated after histopathologic analysis by liver biopsy. The CBC classification scheme outperformed the nonhierachical one against all scheme, achieving an overall accuracy of 98.67% for the normal detector, 87.45% for the chronic hepatitis detector, and 95.71% for the cirrhosis detector.

Enhancing Multimodal Silent Speech Interfaces With Feature Selection

In research on Silent Speech Interfaces (SSI), different sources of information (modalities) have been combined, aiming at obtaining better performance than the individual modalities. However, when combining these modalities, the dimensionality of the feature space rapidly increases, yielding the well-known "curse of dimensionality". As a consequence, in order to extract useful information from this data, one has to resort to feature selection (FS) techniques to lower the dimensionality of the learning space. In this paper, we assess the impact of FS techniques for silent speech data, in a dataset with 4 non-invasive and promising modalities, namely: video, depth, ultrasonic Doppler sensing, and surface electromyography. We consider two supervised (mutual information and Fisher's ratio) and two unsupervised (meanmedian and arithmetic mean geometric mean) FS filters. The evaluation was made by assessing the classification accuracy (word recognition error) of three well-known classifiers (knearest neighbors, support vector machines, and dynamic time warping). The key results of this study show that both unsupervised and supervised FS techniques improve on the classification accuracy on both individual and combined modalities. For instance, on the video component, we attain relative performance gains of 36.2% in error rates. FS is also useful as pre-processing for feature fusion. Copyright © 2014 ISCA.

Transmodalidad y divergencia informacional en la enseñanza de danza

La estructura temporal de los ejercicios de técnica de danza ejecutados por los estudiantes (bailarines en contexto académico) suele estar organizada para responder a un marco métrico musical a menudo sostenido por un acompañante musical de danza. La consigna de estos ejercicios es transmitida multimodalmente por un profesor de danza. A pesar de haber entre ellos un acuerdo tácito para codi car y decodi car métricamente esta información multimodal, se producen frecuentes desentendimientos. Adoptamos como marco teórico un modelo de interacción triádica que describe la relación interpersonal en situación ecológica de clase. Planteamos la hipótesis de que los desentendimientos referidos se producen debido a divergencias en la información multimodal que pueden presentar las consignas. Tomando una metodología microgenética, analizamos una unidad de danza según criterios taxonómicos previamente estudiados. Los resultados muestran que la consigna conlleva información métrica y proposicional contradictoria. Concluimos que, como consecuencia de estas divergencias informacionales, los estudiantes produjeron respuestas motrices altamente desajustadas.

Arrow Plot: a new graphical tool for selecting up and down regulated genes and genes differentially expressed on samples subgroups

Background: A common task in analyzing microarray data is to determine which genes are differentially expressed across two (or more) kind of tissue samples or samples submitted under experimental conditions. Several statistical methods have been proposed to accomplish this goal, generally based on measures of distance between classes. It is well known that biological samples are heterogeneous because of factors such as molecular subtypes or genetic background that are often unknown to the experimenter. For instance, in experiments which involve molecular classification of tumors it is important to identify significant subtypes of cancer. Bimodal or multimodal distributions often reflect the presence of subsamples mixtures. Consequently, there can be genes differentially expressed on sample subgroups which are missed if usual statistical approaches are used. In this paper we propose a new graphical tool which not only identifies genes with up and down regulations, but also genes with differential expression in different subclasses, that are usually missed if current statistical methods are used. This tool is based on two measures of distance between samples, namely the overlapping coefficient (OVL) between two densities and the area under the receiver operating characteristic (ROC) curve. The methodology proposed here was implemented in the open-source R software. Results: This method was applied to a publicly available dataset, as well as to a simulated dataset. We compared our results with the ones obtained using some of the standard methods for detecting differentially expressed genes, namely Welch t-statistic, fold change (FC), rank products (RP), average difference (AD), weighted average difference (WAD), moderated t-statistic (modT), intensity-based moderated t-statistic (ibmT), significance analysis of microarrays (samT) and area under the ROC curve (AUC). On both datasets all differentially expressed genes with bimodal or multimodal distributions were not selected by all standard selection procedures. We also compared our results with (i) area between ROC curve and rising area (ABCR) and (ii) the test for not proper ROC curves (TNRC). We found our methodology more comprehensive, because it detects both bimodal and multimodal distributions and different variances can be considered on both samples. Another advantage of our method is that we can analyze graphically the behavior of different kinds of differentially expressed genes. Conclusion: Our results indicate that the arrow plot represents a new flexible and useful tool for the analysis of gene expression profiles from microarrays.

A biosignal embedded system for physiological computing

Thesis submitted in the fulfilment of the requirements for the Degree of Master in Electronic and Telecomunications Engineering

How new online communication tools and the availability of content influence the audiences and the creative process

We live in a changing world. At an impressive speed, every day new technological resources appear. We increasingly use the Internet to obtain and share information, and new online communication tools are emerging. Each of them encompasses new potential and creates new audiences. In recent years, we witnessed the emergence of Facebook, Twitter, YouTube and other media platforms. They have provided us with an even greater interactivity between sender and receiver, as well as generated a new sense of community. At the same time we also see the availability of content like it never happened before. We are increasingly sharing texts, videos, photos, etc. This poster intends to explore the potential of using these new online communication tools in the cultural sphere to create new audiences, to develop of a new kind of community, to provide information as well as different ways of building organizations’ memory. The transience of performing arts is accompanied by the need to counter that transience by means of documentation. This desire to ‘save’ events reaches its expression with the information archive of the different production moments as well as the opportunity to record the event and present it through, for instance, digital platforms. In this poster we intend to answer the following questions: which online communication tools are being used to engage audiences in the cultural sphere (specifically between theater companies in Lisbon)? Is there a new relationship with the public? Are online communication tools creating a new kind of community? What changes are these tools introducing in the creative process? In what way the availability of content and its archive contribute to the organization memory? Among several references, we will approach the two-way communication model that James E. Grunig & Todd T. Hunt (1984) already presented and the concept of mass self-communication of Manuel Castells (2010). Castells also tells us that we have moved from traditional media to a system of communication networks. For Scott Kirsner (2010), we have entered an era of digital creativity, where artists have the tools to do what they imagined and the public no longer wants to just consume cultural goods, but instead to have a voice and participate. The creativity process is now depending on the public choice as they wander through the screen. It is the receiver who owns an object which can be exchanged. Virtual reality has encouraged the receiver to abandon its position of passive observer and to become a participant agent, which implies a challenge to organizations: inventing new forms of interfaces. Therefore, we intend to find new and effective online tools that can be used by cultural organizations; the best way to manage them; to show how organizations can create a community with the public and how the availability of online content and its archive can contribute to the organizations’ memory.

Do Parlamento para os jornais: reflexos mediáticos dos debates da IVG em 20 anos de democracia portuguesa

O presente artigo centra-se no estudo de caso dos debates da IVG (Interrupção Voluntária da Gravidez) na Assembleia da República em 1984, 1997 e 1998 e nas representações na imprensa das deputadas parlamentares que protagonizaram a discussão. O texto insere-se no âmbito do Projeto “Política no feminino: políticas de género e estratégias de visibilidade das deputadas parlamentares em Portugal”, que tem como objetivo o estudo da representação das deputadas e das questões de género no Parlamento em diferentes ciclos políticos da democracia portuguesa desde 1975 a 2002. A exposição far-se-á segundo três eixos: 1. A apresentação geral da investigação e a contextualização política do debate durante os diversos ciclos sobre o fim da ilicitude nos casos de IVG; 2. A análise da representatividade das deputadas durante o período em estudo, que corresponde à II, III, VII e VIII Legislaturas; 3. A representação das deputadas parlamentares na imprensa, suportada na análise fotojornalística em que se procurou detetar, a partir de uma perspetiva multimodal, os valores profissionais e não profissionais observáveis nas fotografias das deputadas e dos deputados que intervieram nos debates.

O feminino como "intruso" na política: uma análise do contexto histórico e da representação fotojornalística das deputadas portuguesas no "parlamento paritário" e nas discussões da lei da paridade

Na primeira parte deste artigo analisa-se, numa perspetiva histórica, os momentos chave da agenda internacional e nacional sobre o empoderamento das mulheres e os percursos da discussão política sobre quotas e paridade. Trata-se também de caracterizar a situação social das mulheres portuguesas durante a década de 90, bem como as posições ideológicas das diversas maiorias, permitindo compreender o contexto de emergência daquelas questões. Na segunda parte, centramo-nos na cobertura fotojornalística dos três debates parlamentares sobre o assunto da paridade - o “parlamento paritário” (1994) e a discussão e votação das leis das quotas (1991) e da paridade (2001). Discute-se o modo como cinco jornais generalistas portugueses usaram as imagens para investir alguns valores na construção de género, nomeadamente através de um estudo comparativo das diferenças e semelhanças de representação entre deputados e deputadas em cada um desses momentos. São apresentados e discutidos os dados quantitativos resultantes da aplicação de uma grelha de análise de imagem especificamente criada para o efeito e é feita uma análise qualitativa multimodal da cobertura fotojornalística efetuada pelo O Independente durante o Parlamento Paritário e pelo Diário de Notícias durante a Lei das Quotas. As conclusões apontam para a adequação do discurso jornalístico, quer visual quer textual, às tradicionais formas patriarcais de representação do feminino que o dissocia do poder e da liderança, configurando-o como “intruso” na política e não como parceiro de pleno direito. Este “conservadorismo” dos media não facilita a mudança dos valores sociais necessários ao desenvolvimento da participação política feminina.

Assessment of the quality of brain regions and neuroimaging metrics as biomarkers of Alzheimer’s disease

Alzheimer Disease (AD) is characterized by progressive cognitive decline and dementia. Earlier diagnosis and classification of different stages of the disease are currently the main challenges and can be assessed by neuroimaging. With this work we aim to evaluate the quality of brain regions and neuroimaging metrics as biomarkers of AD. Multimodal Imaging Brain Connectivity Analysis (MIBCA) toolbox functionalities were used to study AD by T1weighted, Diffusion Tensor Imaging and 18FAV45 PET, with data obtained from the AD Neuroimaging Initiative database, specifically 12 healthy controls (CTRL) and 33 patients with early mild cognitive impairment (EMCI), late MCI (LMCI) and AD (11 patients/group). The metrics evaluated were gray-matter volume (GMV), cortical thickness (CThk), mean diffusivity (MD), fractional anisotropy (FA), fiber count (FiberConn), node degree (Deg), cluster coefficient (ClusC) and relative standard-uptake-values (rSUV). Receiver Operating Characteristic (ROC) curves were used to evaluate and compare the diagnostic accuracy of the most significant metrics and brain regions and expressed as area under the curve (AUC). Comparisons were performed between groups. The RH-Accumbens/Deg demonstrated the highest AUC when differentiating between CTRLEMCI (82%), whether rSUV presented it in several brain regions when distinguishing CTRL-LMCI (99%). Regarding CTRL-AD, highest AUC were found with LH-STG/FiberConn and RH-FP/FiberConn (~100%). A larger number of neuroimaging metrics related with cortical atrophy with AUC>70% was found in CTRL-AD in both hemispheres, while in earlier stages, cortical metrics showed in more confined areas of the temporal region and mainly in LH, indicating an increasing of the spread of cortical atrophy that is characteristic of disease progression. In CTRL-EMCI several brain regions and neuroimaging metrics presented AUC>70% with a worst result in later stages suggesting these indicators as biomarkers for an earlier stage of MCI, although further research is necessary.

A web-based platform for biosignal visualization and annotation

With the advent of wearable sensing and mobile technologies, biosignals have seen an increasingly growing number of application areas, leading to the collection of large volumes of data. One of the difficulties in dealing with these data sets, and in the development of automated machine learning systems which use them as input, is the lack of reliable ground truth information. In this paper we present a new web-based platform for visualization, retrieval and annotation of biosignals by non-technical users, aimed at improving the process of ground truth collection for biomedical applications. Moreover, a novel extendable and scalable data representation model and persistency framework is presented. The results of the experimental evaluation with possible users has further confirmed the potential of the presented framework.