First-order turbulence closure for modelling complex canopy flows

Simple first-order closure remains an attractive way of formulating equations for complex canopy flows when the aim is to find analytic or simple numerical solutions to illustrate fundamental physical processes. Nevertheless, the limitations of such closures must be understood if the resulting models are to illuminate rather than mislead. We propose five conditions that first-order closures must satisfy then test two widely used closures against them. The first is the eddy diffusivity based on a mixing length. We discuss the origins of this approach, its use in simple canopy flows and extensions to more complex flows. We find that it satisfies most of the conditions and, because the reasons for its failures are well understood, it is a reliable methodology. The second is the velocity-squared closure that relates shear stress to the square of mean velocity. Again we discuss the origins of this closure and show that it is based on incorrect physical principles and fails to satisfy any of the five conditions in complex canopy flows; consequently its use can lead to actively misleading conclusions.

The relative perceptual weight of two Swedish prosodic contrasts

Abstract. In addition to 9 vowel and 18 consonant phonemes, Swedish has three prosodic phonemic contrasts: word stress, quantity and tonal word accent. There are also examples of distinctive phrase or sentence stress, where a verb can be followed by either an unstressed preposition or a stressed particle. This study focuses on word level and more specifically on word stress and tonal word accent in disyllabic words. When making curriculums for second language learners, teachers are helped by knowing which phonetic or phonological features are more or less crucial for the intelligibility of speech and there are some structural and anecdotal evidence that word stress should play a more important role for intelligibility of Swedish, than the tonal word accent. The Swedish word stress is about prominence contrasts between syllables, mainly signaled by syllable duration, while the tonal word accent is signaled mainly by pitch contour. The word stress contrast, as in armen [´arːmən] ‘the arm’ - armén [ar´meːn] ‘the army’, the first word trochaic and the second iambic, is present in all regional varieties of Swedish, and realized with roughly the same acoustic cues, while the tonal word accent, as in anden [´anːdən] ‘the duck’ - anden [`anːdən] ‘the spirit’ is absent in some dialects (as well as in singing), and also signaled with a variety of tonal patterns depending on region. The present study aims at comparing the respective perceptual weight of the two mentioned contrasts. Two lexical decision tests were carried out where in total 34 native Swedish listeners should decide whether a stimulus was a real word or a non-word. Real words of all mentioned categories were mixed with nonsense words and words that were mispronounced with opposite stress pattern or opposite tonal word accent category. The results show that distorted word stress caused more non-word judgments and more loss, than distorted word accent. Our conclusion is that intelligibility of Swedish is more sensitive to distorted word stress pattern than to distorted tonal word accent pattern. This is in compliance with the structural arguments presented above, and also with our own intuition.

Mapa perceptual dos compradores de apartamentos em Porto Alegre

A indústria da construção civil é extremamente importante para a economia brasileira, particularmente no momento em que o Brasil apresenta elevados índices de desemprego. O setor utiliza mão-de-obra intensiva, possui baixa dependência de insumos importados e representa 19,26% do Produto Interno Bruto do Brasil. Entretanto, juros elevados, baixo ritmo de crescimento da economia, escassez de crédito e baixo poder aquisitivo da população contribuem para a falta de investimentos no setor e o acirramento da competição entre as empresas construtoras. Para sobreviver e prosperar neste ambiente as empresas devem buscar a diferenciação através da geração de valor para o cliente, oferecendo- lhe produtos cujos atributos sejam por ele valorizados. O objetivo desta pesquisa é o de mapear os atributos valorizados pelos compradores de apartamentos em Porto Alegre na faixa de preço em torno de R$90.000,00 a R$165.000,00 e identificar os segmentos (clusters) de consumidores contidos na amostra. Inicialmente foi feita uma pesquisa de atributos encontrados na literatura, os quais foram validados por expertos e compradores, resultando em uma lista com 60 atributos. A partir dela foi elaborado um questionário estruturado, contendo questões para avaliar o grau de importância atribuído pelos compradores aos atributos, bem como questões sobre sua situação sócio-econômica. Realizaram-se trezentas entrevistas por telefone com uma amostra não probabilística, obtida por conveniência e acessibilidade. Diversas técnicas estatísticas foram aplicadas aos dados, possibilitando a execução de um mapa perceptual. Primeiramente, através de uma análise fatorial, os sessenta atributos foram reduzidos a vinte e um fatores. A seguir, por meio de uma análise de clusters, foram identificados cinco segmentos (clusters). Por último, uma análise discriminante identificou catorze fatores discriminantes entre os segmentos. A análise discriminante também forneceu as correlações entre as funções discriminantes e os fatores discriminantes, bem como os centróides dos segmentos. Os segmentos e os fatores discriminantes foram dispostos no mapa perceptual na forma de pontos e vetores, respectivamente. A análise do mapa permite identificar quais fatores são comparativamente mais ou menos valorizados por determinado segmento. O detalhamento e riqueza das informações obtidas na análise do mapa perceptual, somadas à sensibilidade e à criatividade dos profissionais responsáveis pelo desenvolvimento dos produtos imobiliários podem ser um passo decisivo em direção ao sucesso dos empreendimentos.

Perceptual aspects of the use of faucets (taps)

This paper presents an assessment with simulated activities with the aim of analyzing the perception of ease/difficulty of the use of faucets (taps) handles by 180 Brazilian adults. Five different handles faucets were activated for subsequent collection of perceptual data. The procedures were based on main recommendations for biomedical ethics and human research. The results indicate that handles with levers are significantly (p <= 0.05) easier to use. The most difficult are characterized by not having support points for the rotation (levers) or more points of pressure concentration in the hand.

Desempenho perceptual-auditivo e ortográfico de consoantes fricativas na aquisição da escrita

OBJETIVO: Verificar os desempenhos perceptual-auditivo e ortográfico de escolares no que se refere à identificação de contrastes entre as fricativas do Português Brasileiro, e investigar em que medida esses dois tipos de desempenhos se relacionam. MÉTODOS: Foram analisados dados de desempenho perceptual-auditivo e de desempenho ortográfico extraídos de 20 crianças das duas primeiras séries do ensino fundamental de uma escola pública do município de Mallet (PR). A coleta de dados de percepção auditiva foi feita com base no Instrumento de Avaliação da Percepção de Fala (PERCEFAL), com o uso do software Perceval. Já a coleta de dados de ortografia foi feita por meio de um ditado das mesmas palavras que compõem o instrumento PERCEFAL. RESULTADOS: Foram observadas: maior acurácia perceptual-auditiva do que ortográfica; tendência de menor tempo de resposta e de menor variabilidade nos acertos perceptuais-auditivos do que nos erros; não correspondência de erros de percepção-auditiva e ortografia, já que, na percepção, o maior percentual de erros envolveu o ponto de articulação das fricativas, enquanto que, na ortografia, o maior percentual envolveu o vozeamento. CONCLUSÃO: Embora se mostrem relacionados, os desempenhos perceptual-auditivo e ortográfico não apresentam correspondência termo a termo. Portanto, na prática clínica, a atenção deve-se voltar não apenas para os aspectos que aproximam esses dois desempenhos, mas, também, para os aspectos que os diferenciam.

Acoustic and perceptual analyses of Brazilian male actors' and nonactors' voices: Long-term average spectrum and the Actor's Formant

This study investigates the possible differences between actors' and nonactors' vocal projection strategies using acoustic and perceptual analyses. A total of 11 male actors and 10 male nonactors volunteered as subjects, reading an extended text sample in habitual, moderate, and loud levels. The samples were analyzed for sound pressure level (SPL), alpha ratio (difference between the average SPL of the 1-5 kHz region and the average SPL of the 50 Hz-1 kHz region), fundamental frequency (F0), and long-term average spectrum (LTAS). Through LTAS, the mean frequency of the first formant (171) range, the mean frequency of the actor's formant, the level differences between the F1 frequency region and the F0 region (L1-L0), and the level differences between the strongest peak at 0-1 kHz and that at 3-4 kHz were measured. Eight voice specialists evaluated perceptually the degree of projection, loudness, and tension in the samples. The actors had a greater alpha ratio, stronger level of the actor's formant range, and a higher degree of perceived projection and loudness in all loudness levels. SPL, however, did not differ significantly between the actors and nonactors, and no differences were found in the mean formant frequencies ranges. The alpha ratio and the relative level of the actor's formant range seemed to be related to the degree of perceived loudness. From the physiological point of view, a more favorable glottal setting' providing a higher glottal closing speed, may be characteristic of these actors' projected voices. So, the projected voices, in this group of actors, were more related to the glottic source than to the resonance of the vocal tract.

Ectopic mineralization of articular cartilage in the bullfrog Rana catesbeiana and its possible involvement in bone closure

Mineralization of the articular cartilage is a pathological condition associated with age and certain joint diseases in humans and other mammals. In this work, we describe a physiological process of articular cartilage mineralization in bullfrogs. Articular cartilage of the proximal and distal ends of the femur and of the proximal end of the tibia-fibula was studied in animals of different ages. Mineralization of the articular cartilage was detected in animals at 1 month post-transformation. This mineralization, which appeared before the hypertrophic cartilage showed any calcium deposition, began at a restricted site in the lateral expansion of the cartilage and then progressed to other areas of the epiphyseal cartilage. Mineralized structures were identified by von Kossa's staining and by in vivo incorporation of calcein green. Element analysis showed that calcium crystals consisted of poorly crystalline hydroxyapatite. Mineralized matrix was initially spherical structures that generally coalesced after a certain size to occupy larger areas of the cartilage. Alkaline phosphatase activity was detected at the plasma membrane of nearby chondrocytes and in extracellular matrix. Apoptosis was detected by the TUNEL (TDT-mediated dUTP-biotin nick end-labeling) reaction in some articular chondrocytes from mineralized areas. The area occupied by calcium crystals increased significantly in older animals, especially in areas under compression. Ultrastructural analyses showed clusters of needle-like crystals in the extracellular matrix around the chondrocytes and large blocks of mineralized matrix. In 4-year-old animals, some lamellar bone (containing bone marrow) occurred in the same area as articular cartilage mineralization. These results show that the articular cartilage of R. catesbeiana undergoes precocious and progressive mineralization that is apparently stimulated by compressive forces. We suggest that this mineralization is involved in the closure of bone extremities, since mineralization appears to precede the formation of a rudimentary secondary center of ossification in older animals.