Perceptions of Jordanian laypersons and dental professionals to altered smile aesthetics.

The purposes of this study were to rate the attractiveness of different smile variables, to compare the perception of Jordanian laypeople, general practitioners, and orthodontists to altered smile aesthetics, and to identify the threshold where different variables begin to impair smile aesthetics. A smiling photograph of a female dental student was selected and digitally manipulated to create changes in buccal corridor space (BCS), the amount of gingival display, and the midline diastema. These altered images were rated by three groups of Jordanians: 200 laypeople (100 females and 100 males), 200 general practitioners (100 females and 100 males), and 160 orthodontists (40 females and 120 males). Smile aesthetics scores were calculated and comparisons between groups were performed using the univariate general linear model. The results showed that profession and gender affected BCS and midline diastema attractiveness ratings (P<0.001). Wide BCSs, a gingival display of more than 2 mm, and the presence of a midline diastema of any size were rated as unattractive by all groups.

Pattern recognition in correlated and uncorrelated noise.

This study examined how correlated, or filtered, noise affected efficiency for recognizing two types of signal patterns, Gabor patches and three-dimensional objects. In general, compared with the ideal observer, human observers were most efficient at performing tasks in low-pass noise, followed by white noise; they were least efficient in high-pass noise. Simulations demonstrated that contrast-dependent internal noise was likely to have limited human performance in the high-pass conditions for both signal types. Classification images showed that observers were likely adopting different strategies in the presence of low-pass versus white noise. However, efficiencies were underpredicted by the linear classification images and asymmetries were present in the classification subimages, indicating the influence of nonlinear processes. Response consistency analyses indicated that lower contrast-dependent internal noise contributed somewhat to higher efficiencies in low-pass noise for Gabor patches but not objects. Taken together, the results of these experiments suggest a complex interaction among signals, external noise spectra, and internal noise in determining efficiency in correlated and uncorrelated noise.

Classification images for simple detection and discrimination tasks in correlated noise.

We use the classification image technique to investigate the effect of white noise and various correlated Gaussian noise textures (low-pass, high-pass, and band-pass) on observer performance in detection and discrimination tasks. For these tasks, performance is generally enhanced by an observer's ability to "prewhiten" correlated noise as part of the formation of a decision variable. We find that observer efficiency in these tasks is well represented by the measured classification images and that human observers show strong evidence of adaptation to different correlated noise textures. This adaptation is captured in the frequency weighting of the classification images.

An impact analysis of the application of the threshold of toxicological concern concept to pharmaceuticals.

The recent application of the threshold of toxicological concern (TTC) concept to the regulation of pharmaceuticals in the European Union is analyzed. The derivation of TTC and the threshold of regulation that followed it were originally intended to provide makers of food contact materials greater flexibility with their products, while allowing the CFSAN branch of FDA to conserve its resources for more important issues. A reanalysis of the scientific data employed by EMEA regulators to rationalize its 1.5 mcg default genotoxic impurity limit is presented to demonstrate (a) that direct translation of conclusions relevant to food consumption are unduly influenced by many classes of potent carcinogens of historic concern which would be impossible to generate unknowingly as pharmaceutical impurities, and (b) that the majority of reactive chemicals that would be useful to synthetic chemists are among the least potent carcinogens in the underpinning supportive analyses. Evidence is further presented to show that implementation and acceptance of a 1.5 mcg TTC-based total limit on such impurities can be expected to impede pharmaceutical research and development efficiency while providing an insignificant cancer risk-avoidance benefit to patients who require pharmaceutical treatments. The conclusion drawn is that a significantly higher default limit can readily be defended that would be both in keeping with TTC principles and the best interest of patients.

Agrupamento de sensações somatossensoriais com estimulação de corrente senoidal / Clustering of somatosensory sensations during sinusoidal current stimulation

Fibras finas (FF) aferentes primárias mediam a percepção de sensações relacionadas à dor e à temperatura, e as fibras grossas (FG) ao tato. O objetivo deste trabalho é avaliar percepções relacionadas às FF (picada, pontada, agulhada, queimação) e às FG (aperto, pressão, vibração e movimento)evocadas por estimulação elétrica senoidal com 5 Hz e 2 kHz, respectivamente. O dedo indicador da mão esquerda de 150 voluntários, sem doença neurológica conhecida e medicação, foram estimulados nessas frequências com intensidades decorrente igual ao limiar de sensibilidade (LS) e 1,5 vezes LS.O voluntário escolheu das 8 palavras, 3 que mais se aproximavam à sua percepção do estímulo. Outro grupo de 60 voluntários foi utilizado como controle, sendo que as 3 palavras foram escolhidas sem nenhuma estimulação. O valor de “1” foi atribuído à palavra escolhida, e “0” à não selecionada. As sensações foram agrupadas utilizando-se o vizinho mais próximo (single linkage) e a correlação entre variáveis binárias(tetrachloric correlation). Os resultados indicam uma tendência a sensações de fibras grossas sem estimulação, sendo que 5 Hz evoca principalmente as sensações de fibras finas e 2 kHz as de fibras grossas. A exceção foi a sensação de FF queimação, a qual se mostrou inconsistente em ambos os grupos.

Thin fibers mediate the perception related to temperature and painful sensations, and thick fibers the perception related to touch. This work tries to evaluate the perceptions related to thin (prick, pang, twinge and burning) and thick fibers (squeeze, pressure, movement and vibration) evoked by sinusoidal stimulation with 5 Hz and2 kHz, respectively. The left index fingers of 150 volunteers, without known neurological problems or under medication, were stimulatedat these frequencies and at current intensities equal to the sensory threshold and 1.5 times the sensory threshold. The volunteers chose three words out of eight that better represented the sensation felt during the stimulus. Another group of 60 volunteers was used as control, for which the three words were chosen with no stimulation. The value “1” was attributed to each sensation chosen and “0” forthe others. The sensations were clustered using the single linkage nearest neighbor method and the tetrachloric correlation between binary variables. The results showed a tendency to thick fiber sensations with 2 kHz or no stimulation, while 5 Hz evoked thin fiber sensations. The exception was the FF sensation of burning, which did not fit into any group.