Study on the Application of Kramers-Kronig Relation for Polyurethane Mixture.

Polyurethane (PU) mixture, which is a new pavement mixture, exhibits different dynamic properties compared to a hot-mixed asphalt mixture (HMA). This paper analyzed whether the Kramers-Kronig (K-K) relation and thermorheologically simple properties applied to the PU mixture. Based on the results, the PU mixture exhibited thermorheologically simple properties within the test conditions. The time-temperature superposition principle (TTSP) was applicable for the PU mixture to construct a dynamic modulus master curve using the standard logistic sigmoidal (SLS) model, the generalized logistic sigmoidal (GLS) model, and the Havriliak-Negami (HN) model. The Hilbert integral transformed SLS and GLS models for the phase angle can accurately fit the measured phase angle data with newly fitted shift factors and predict the phase angle within the viscoelastic range. The core-core and black space diagrams both displayed single continuous smooth curves, which can be utilized to characterize the viscoelastic property of the PU mixture. The K-K relation is applicable for the PU mixture to obtain the phase angle master curve model, storage modulus, and loss modulus from the complex modulus test results with the test temperatures and loading frequencies. The phase angle of the PU mixture at extremely high or low test temperatures cannot be derived from the dynamic modulus data.

An eye-tracking and visual analogue scale attractiveness evaluation of black space between the maxillary central incisors

ABSTRACT Objective: To study the influence of black space between the maxillary central incisors on the aesthetic visual perception of the face, via eye-tracking and visual analogue scale (VAS). Methods: Black space between the central incisors was created, for both sexes, as follows: control, 1-mm black space, 2-mm black space and 3-mm black space. Ninety raters participated in this study, divided into three groups: 30 laypeople, 30 nonorthodontists, and 30 orthodontists. After the visual calibration of each observer, eight photographs were presented in the Ogama® software concomitant with the use of the hardware The Eye Tribe®. Ogama generated information depending on the eye-tracking of each rater, regarding the time until the first fixation, time of fixation, heatmap, scanpath, and total time of fixation, to evaluate the areas deemed to be of interest according to the raters. Later on, the VAS was used, where each rater evaluated the images in an album on a scale of zero to 10 points. Results: The eyes and mouth were the areas more often noticed by the raters according to the heatmaps, while no significant difference was observed in time until the first fixation between the three groups of raters (p> 0.05). However, regarding the time of fixation on the mouth, a significant difference was observed (p< 0.05) when comparing the three groups. Conclusion: Black space has a negative effect on the aesthetic perception of the face. The amount of attention on the mouth is correspondent to the size of the black space.

RESUMO Objetivo: Avaliar a percepção visual e estética do espaço negro entre os incisivos centrais superiores, via rastreamento do olhar e escala visual analógica (EVA). Métodos: Manipulou-se o espaço negro entre os incisivos centrais superiores, para ambos os sexos, da seguinte forma: imagem controle, espaço negro de 1 mm, espaço negro de 2 mm e espaço negro de 3 mm. Participaram desse estudo noventa avaliadores, divididos em três grupos: 30 leigos, 30 cirurgiões-dentistas e 30 ortodontistas. Após a calibração visual de cada observador, foram projetadas oito fotografias no software OGAMA® em conjunto com o hardware The Eye Tribe®. O OGAMA gerou informações do rastreamento do olhar de cada avaliador com relação ao tempo até a primeira fixação, mapa de calor, trajetória do olhar e tempo total de fixação para avaliar as áreas consideradas de interesse, de acordo com os avaliadores. Posteriormente, utilizou-se a EVA para avaliar as imagens a partir de um álbum, em uma escala de 0 a 10 pontos. Resultados: Os olhos e a boca foram as áreas com maior fixação pelos avaliadores, de acordo com os mapas de calor. Os resultados estatísticos não apresentaram diferença estatisticamente significativa entre os três grupos de avaliadores (p> 0,05), quanto ao tempo até a primeira fixação. Porém, em relação ao tempo de fixação na boca, observou-se diferença estatisticamente significativa (p< 0,05) na comparação dos três grupos. Conclusão: O espaço negro apresentou um efeito negativo na percepção estética da face. O aumento de fixação na boca correspondeu ao aumento do tamanho do espaço negro.

Evaluation of black spaces between maxillary central incisors by dentistry students and laypeople.

This study aimed to compare the perception of smile esthetics and alterations among dentistry degree students and laypeople to identify differences in the esthetic perception of black spaces between the maxillary central incisors among Turkish laypeople and students in different study years. Photographs altered to include black spaces of various sizes at the midline were evaluated by 208 dentistry students in years 1-5 and 45 Turkish laypeople. Perceptional differences in different photographs were statistically significant. The students in years 2-5 were more aware of differences between photographs than year 1 students and laypeople. The proportion of participants who decided the most attractive photograph as A was highest among 3rd year students, followed by 5th year students. However, the proportion of students agreeing on the least attractive image was highest among 4th year students, followed by 3rd year students. Photographs A and H were selected as the most and least attractive, respectively, by all participants. The esthetic perception of 1st and 2nd year dentistry students was very different from that of laypeople. To increase esthetic perception among dentistry students, specific lessons with clinical photography should be included in dental education.