The effects of oculomotor instability on visual performance of people with macular disease

Background: People with macular disease often face difficulties using their preferred retinal locus (PRL) during visual tasks. These difficulties are due to impaired oculomotor control, amongst other causes. The aim of this work was to investigate whether stabilizing the visual target at the PRL is beneficial for visual acuity and reading. Methods: Control of retinal image instability at the PRL was achieved using an eyetracker that moved the target according to the eye movements. Crowded and uncrowded visual acuity was measured at the PRL in people with macular disease and in healthy peripheral retina of control subjects. RSVP reading speed was also measured using the same method of stabilization at the PRL and healthy peripheral retina. Results: Results of a series of experiments showed that stabilizing the visual target can improve visual performance in most cases. In healthy peripheral retina crowded visual acuity improved when the image was stabilized and reduced when fixation instability was over-compensated. At the PRL, in patients, no improvement in visual acuity was obtained under stabilized conditions and again visual acuity reduced for over-compensated fixation instability. However, reading speed improved under stabilized conditions, by 20% in healthy peripheral retina of control subjects, and by up to 40% at the PRL of people with macular disease. Discussion: Good oculomotor control is critical for complex crowded tasks like reading. The improvement in reading speed found whilst compensating for oculomotor instability at the PRL is encouraging. These results indicate that training programs which aim to improve fixation control are likely to bring benefits for visual tasks. The observed increase in reading speed might be clinically relevant but the technique used to control instability needs simplification to be implemented outside the laboratory

Integrating the data envelopment analysis and the balanced scorecard approaches for enhanced performance assessment

This article presents the development of a conceptual framework which aims to assess Decision Making Units (DMUs)from multiple perspectives. The proposed conceptual framework combines the Balanced Scorecard(BSC)method with the non-parametric technique known as Data Envelopment Analysis (DEA) by using various interconnected models which try to encapsulate four perspectives of performance (financial, customers, internal processes,learning and growth). The practical relevance of the conceptual model has been tested by using it to assess the performance of DMUs in a multinational company which operates in two business areas.Various models were developed with the collaboration of the directors of the company in order to conceive an appropriate and consensual framework, which may provide useful information for the company.The application of the conceptual framework provides structured information regarding the performance of each DMU(from multiple perspectives)and ways to improve it.By integrating the BSC and the DEA approaches this research helps to identify where there is room for improving organisational performance and points out opportunities for reciprocal learning between DMUs.In doing so,this article provides a set of recommendations relating to the successful application of DEA and its integration with the BSC,in order to promote a continuous learning process and to bring about improvements in performance

Capim-braquiária sob lotação contínua e com altura única ou variável durante as estações do ano: morfogênese e dinâmica de tecidos

Este trabalho foi realizado com o objetivo de identificar estratégias eficazes de manejo do pastejo de Brachiaria decumbens cv. Basilisk, sob lotação contínua, com base em avaliações das suas características morfogênicas e estruturais. Duas estratégias de manejo do pastejo foram estudadas: em uma, o pasto foi mantido com 25 cm de altura média durante todo o período experimental e, na outra, foi mantido em 15 cm de altura média durante o inverno, com aumento para 25 cm a partir do início da primavera. Adotou-se o delineamento de blocos casualizados em esquema de parcelas subdivididas com quatro repetições. Consideraram-se, como fator primário, as estratégias de manejo do pastejo, caracterizadas pelas alturas médias dos pastos durante as estações do ano (inverno, primavera e verão), e, como fator secundário, as estações. O rebaixamento do pasto para 15 cm no inverno resultou em maior taxa de aparecimento foliar (0,02 folha/perfilho.dia) e maior número de folhas vivas (4,5 folhas por perfilho) no inverno, mas provocou redução, no inverno, da duração de vida da folha (66 dias), da taxa de senescência foliar (0,22 cm/perfilho.dia) e dos comprimentos da lâmina foliar (11 cm) e pseudocolmo (15,2 cm) em relação ao pasto com 25 cm. Nesta estação, foram menores os valores observados para as taxas de aparecimento foliar (0,06 folha/perfilho.dia), alongamento foliar (0,110 cm/perfilho.dia) e alongamento de pseudocolmo (0,008 cm/perfilho.dia), número de folha viva (2,9 folhas por perfilho) e comprimentos da lâmina foliar (8,6 cm) e do pseudocolmo (13,5 cm). Por outro lado, a duração de vida da folha (139 dias) e o número de folhas mortas (2,0 folhas por perfilho) foram maiores. O maior valor de taxa de senescência foliar ocorreu na primavera (0,40 cm/perfilho.dia). O pasto de B. decumbens cv. Basilisk sob lotação contínua pode ser manejado de forma sazonal, com rebaixamento para 15 cm no início do inverno e posterior aumento para 25 cm no início da primavera.This study was conducted to identify effective strategies for grazing managing of Brachiaria decumbens cv. Basilisk, under continuous stocking, based on assessments of their morphogenetic and structural characteristics. Two strategies of grazing management were studied: in one, the grass was maintained with 25-cm mean height throughout the experimental period, and in the other, it was 15 cm during the winter, rising to 25 cm from the beginning of spring. The split-plot in randomized block design with four replications was adopted. The strategies of grazing management responded to primary factor, characterized by average heights of pastures during the seasons (winter, spring and summer). The seasons corresponded to secondary factor and consisted of measures over the experimental period. Pasture's lowering to 15 cm in the winter resulted in higher leaf appearance rate (0.02 leaves/tiller.day) and higher number of live leaves (4.5 leaves/tiller) in the winter. However, this management strategy lowered leaf lifespan (66 days), leaf senescence rate (0.22 cm/tiller.day), and length of leaf lamina (11 cm) and stem (15.2 cm) in winter months, in relation to pasture with 25 cm. During this season, rates of leaf appearance (0.06 leaves/tiller.day), leaf elongation (0.110 cm/tiller.day) stem elongation (0.008 cm/tiller.day), live leaves (2.9 leaves/tiller), length of leaf lamina (8.6 cm) and stem (13.5 cm) lowered. On the other hand, leaf lifespan (139 days) and number of dead leaves (2.0 leaves/tiller) were higher. The highest leaf senescence rate occurred in the spring (0.40 cm/tiller.day). The B. decumbens cv. Basilisk pasture under continuous stocking can be managed on a seasonal basis, with decrease to 15 cm in early winter, and further increase to 25 cm in early spring