A Simpler and More Accurate AUTO-HDS Framework for Clustering and Visualization of Biological Data

In [1], the authors proposed a framework for automated clustering and visualization of biological data sets named AUTO-HDS. This letter is intended to complement that framework by showing that it is possible to get rid of a user-defined parameter in a way that the clustering stage can be implemented more accurately while having reduced computational complexity

Coralistas amadores: auto-imagem, dificuldades e sintomas na voz cantada

Purpose: to evaluate vocal self-perception, difficulties and presence of negative symptoms after singing of amateur choir singers of different vocal classifications, age and experience. Method: one hundred and twenty five singers answered a questionnaire containing identification data, information about self-perception of the singing voice, difficulties with singing and negative symptoms after singing. Results: the comparison considering vocal classification evidenced greater difficulties with high notes for altos and basses, greater difficulty regarding the transition to high notes for basses and greater vocal fatigue for altos. Comparing the singers by age, both adults and young adults referred more breathiness than the elderly. The adults referred better vocal intensity than the young adults. The young adults referred better timbre than adults. Regarding the experience, the less experienced singers reported self-perception of hoarseness and presence of hoarseness after singing in greater number than the experienced singers. Conclusion: the difficulties with singing are connected to the vocal classification and do not depend on age or experience. Vocal symptoms are related to the vocal classification and to the experience with singing. Negative self-perception is also related the vocal classification and to the experience with singing, and positive self-perception was more reported by experienced singers.

Problemas de estimação de custo de capital de empresas concessionárias no Brasil: uma aplicação à regulamentação de concessões rodoviárias

Neste trabalho, discute-se a fixação de taxas de retorno de concessões no Brasil, com aplicação específica ao caso da metodologia da Agência Nacional de Transportes Terrestres (ANTT). Mostra-se a inadequação da regulamentação vigente, baseada no conceito de taxa interna de retorno (TIR), e não de custo de oportunidade do capital. A partir de um exemplo com dados referentes ao auge da crise financeira internacional (dezembro de 2008), evidencia-se também a falta de lógica decorrente da utilização de retornos e preços passados na estimação de taxas de retorno, um procedimento comum a toda a área de concessões de serviços públicos no Brasil. Propõe-se uma metodologia alternativa cujos resultados são sensíveis às condições correntes de mercado de capitais, que produz resultados coerentes com a situação então vigente.