South America is a territory of 17,819,100 km(2), where ∼388 million people live in 13 countries.... more South America is a territory of 17,819,100 km(2), where ∼388 million people live in 13 countries. In the region, access to medical assistance (e.g., for treatment of cardiovascular disorders) is relatively easy in metropolitan areas but difficult in remote places such as the Andes and the Amazon. Altitudes up to ∼6,700 m influence the prevalence of congenital heart disease (CHD) and pulmonary arterial hypertension (PAH). In tertiary centers, CHD is now treated earlier in life but remains an important etiology of PAH. In adolescents and adults with PAH assisted at institutions devoted to treatment of cardiovascular disorders, the relative frequency of PAH-CHD (∼50%-60%) is even higher than that of idiopathic PAH. In one big tertiary center in São Paulo, Brazil, the prevalence of advanced PAH in children and adults with CHD is 1.2% and 4.2%, respectively. In young patients with cardiac septal defects (aged up to 2 years), pulmonary vascular abnormalities are a matter of concern in the...
Despite the growing popularity of virtual reality environments, few laboratories are equipped to ... more Despite the growing popularity of virtual reality environments, few laboratories are equipped to investigate eye movements within these environments. This primer is intended to reduce the time and effort required to incorporate eye-tracking equipment into a virtual reality environment. We discuss issues related to the initial startup and provide algorithms necessary for basic analysis. Algorithms are provided for the calculation of gaze angle within a virtual world using a monocular eye-tracker in a three-dimensional environment. In addition, we provide algorithms for the calculation of the angular distance between the gaze and a relevant virtual object and for the identification of fixations, saccades, and pursuit eye movements. Finally, we provide tools that temporally synchronize gaze data and the visual stimulus and enable real-time assembly of a video-based record of the experiment using the Quicktime MOV format, available at http://sourceforge.net/p/utdvrlibraries/. This recor...
Philosophical Transactions of the Royal Society B: Biological Sciences, 2013
In addition to stimulus properties and task factors, memory is an important determinant of the al... more In addition to stimulus properties and task factors, memory is an important determinant of the allocation of attention and gaze in the natural world. One way that the role of memory is revealed is by predictive eye movements. Both smooth pursuit and saccadic eye movements demonstrate predictive effects based on previous experience. We have previously shown that unskilled subjects make highly accurate predictive saccades to the anticipated location of a ball prior to a bounce in a virtual racquetball setting. In this experiment, we examined this predictive behaviour. We asked whether the period after the bounce provides subjects with visual information about the ball trajectory that is used to programme the pursuit movement initiated when the ball passes through the fixation point. We occluded a 100 ms period of the ball's trajectory immediately after the bounce, and found very little effect on the subsequent pursuit movement. Subjects did not appear to modify their strategy to prolong the fixation. Neither were we able to find an effect on interception performance. Thus, it is possible that the occluded trajectory information is not critical for subsequent pursuit, and subjects may use an estimate of the ball's trajectory to programme pursuit. These results provide further support for the role of memory in eye movements.
Despite the growing popularity of virtual reality environments, few laboratories are equipped to ... more Despite the growing popularity of virtual reality environments, few laboratories are equipped to investigate eye movements within these environments. This primer is intended to reduce the time and effort required to incorporate eye-tracking equipment into a virtual reality environment. We discuss issues related to the initial startup and provide algorithms necessary for basic analysis. Algorithms are provided for the calculation of gaze angle within a virtual world using a monocular eye-tracker in a three-dimensional environment. In addition, we provide algorithms for the calculation of the angular distance between the gaze and a relevant virtual object and for the identification of fixations, saccades, and pursuit eye movements. Finally, we provide tools that temporally synchronize gaze data and the visual stimulus and enable real-time assembly of a video-based record of the experiment using the Quicktime MOV format, available at http://sourceforge.net/p/utdvrlibraries/. This record contains the visual stimulus, the gaze cursor, and associated numerical data and can be used for data exportation, visual inspection, and validation of calculated gaze movements.
Abstract In 1988 Pelli and Robson developed and produced a letter chart used to determine contras... more Abstract In 1988 Pelli and Robson developed and produced a letter chart used to determine contrast sensitivity in human subjects. An interesting and unintended phenomenon arises when one gets to the lowest-contrast letters. While at first these letters do not appear to be 'there'at all, over an extended amount of time (15–20 seconds) these letters gradually fade into appearance. This extremely long time course is unlike that of any other known mechanism involved in visual recognition. What is the nature of this mechanism and what ...
Journal of Experimental Psychology: Human Perception and Performance, 2012
People can often anticipate the outcome of another person&amp... more People can often anticipate the outcome of another person's actions based on visual information available in the movements of the other person's body. We investigated this problem by studying how goalkeepers anticipate the direction of a penalty kick in soccer. The specific aim was to determine whether the information used to anticipate kick direction is best characterized as local to a particular body segment or distributed across multiple segments. In Experiment 1, we recorded the movements of soccer players as they kicked balls into a net. Using a novel method for analyzing motion capture data, we identified sources of local and distributed information that were reliable indicators of kick direction. In Experiments 2 and 3, subjects were presented with animations of kickers' movements prior to foot-to-ball contact and instructed to judge kick direction. Judgments were consistent with the use of distributed information, with a possible small contribution of local information.
Glucose-6-phosphate dehydrogenase (G6PD) is an important site of metabolic control in the pentose... more Glucose-6-phosphate dehydrogenase (G6PD) is an important site of metabolic control in the pentose phosphate pathway (PPP), providing reducing power (NADPH) and pentose phosphates. The purpose of this study was to investigate the possible involvement of G6PD deficiency (G6PD-) in the pathogenesis of pterygium. Erythrocyte G6PD activity was evaluated in 123 pterygium patients and in 112 age-matched control patients. Enzyme activity, mRNA, rate of growth, green autofluorescence, response to oxidative stress, and cholesterol metabolism were determined in pterygium fibroblasts (PFs) and in normal conjunctival fibroblasts (NCFs) isolated from G6PD normal (NCFs+ and PFs+) and G6PD- (NCFs- and PFs-) patients. Higher prevalence of G6PD- was found in patients affected by primary pterygium than in control subjects, both men and women, suggesting that this enzymatic defect may be a predisposing factor for pterygium. G6PD activity was significantly lower in NCFs- than in NCFs+, but not in PFs- than in PFs+. In PFs-, G6PD mRNA levels were significantly higher than in PFs+. Growth-stimulated NCFs- grew at half the rate of NCFs+, although PFs- and PFs+ grew at the same rate. Increased green autofluorescence and susceptibility to oxidative stress were observed in PFs (+/-) and in NCFs-, but not in NCFs+. Moreover, ex vivo PFs (+/-) accumulated more lipids than corresponding NCFs. The results of this study, although restricted to a limited group of subjects (i.e., those of Sardinian ancestry), suggest that G6PD- not only does not protect against pterygium, but may even be considered a risk factor for the development of this disorder.
South America is a territory of 17,819,100 km(2), where ∼388 million people live in 13 countries.... more South America is a territory of 17,819,100 km(2), where ∼388 million people live in 13 countries. In the region, access to medical assistance (e.g., for treatment of cardiovascular disorders) is relatively easy in metropolitan areas but difficult in remote places such as the Andes and the Amazon. Altitudes up to ∼6,700 m influence the prevalence of congenital heart disease (CHD) and pulmonary arterial hypertension (PAH). In tertiary centers, CHD is now treated earlier in life but remains an important etiology of PAH. In adolescents and adults with PAH assisted at institutions devoted to treatment of cardiovascular disorders, the relative frequency of PAH-CHD (∼50%-60%) is even higher than that of idiopathic PAH. In one big tertiary center in São Paulo, Brazil, the prevalence of advanced PAH in children and adults with CHD is 1.2% and 4.2%, respectively. In young patients with cardiac septal defects (aged up to 2 years), pulmonary vascular abnormalities are a matter of concern in the...
Despite the growing popularity of virtual reality environments, few laboratories are equipped to ... more Despite the growing popularity of virtual reality environments, few laboratories are equipped to investigate eye movements within these environments. This primer is intended to reduce the time and effort required to incorporate eye-tracking equipment into a virtual reality environment. We discuss issues related to the initial startup and provide algorithms necessary for basic analysis. Algorithms are provided for the calculation of gaze angle within a virtual world using a monocular eye-tracker in a three-dimensional environment. In addition, we provide algorithms for the calculation of the angular distance between the gaze and a relevant virtual object and for the identification of fixations, saccades, and pursuit eye movements. Finally, we provide tools that temporally synchronize gaze data and the visual stimulus and enable real-time assembly of a video-based record of the experiment using the Quicktime MOV format, available at http://sourceforge.net/p/utdvrlibraries/. This recor...
Philosophical Transactions of the Royal Society B: Biological Sciences, 2013
In addition to stimulus properties and task factors, memory is an important determinant of the al... more In addition to stimulus properties and task factors, memory is an important determinant of the allocation of attention and gaze in the natural world. One way that the role of memory is revealed is by predictive eye movements. Both smooth pursuit and saccadic eye movements demonstrate predictive effects based on previous experience. We have previously shown that unskilled subjects make highly accurate predictive saccades to the anticipated location of a ball prior to a bounce in a virtual racquetball setting. In this experiment, we examined this predictive behaviour. We asked whether the period after the bounce provides subjects with visual information about the ball trajectory that is used to programme the pursuit movement initiated when the ball passes through the fixation point. We occluded a 100 ms period of the ball's trajectory immediately after the bounce, and found very little effect on the subsequent pursuit movement. Subjects did not appear to modify their strategy to prolong the fixation. Neither were we able to find an effect on interception performance. Thus, it is possible that the occluded trajectory information is not critical for subsequent pursuit, and subjects may use an estimate of the ball's trajectory to programme pursuit. These results provide further support for the role of memory in eye movements.
Despite the growing popularity of virtual reality environments, few laboratories are equipped to ... more Despite the growing popularity of virtual reality environments, few laboratories are equipped to investigate eye movements within these environments. This primer is intended to reduce the time and effort required to incorporate eye-tracking equipment into a virtual reality environment. We discuss issues related to the initial startup and provide algorithms necessary for basic analysis. Algorithms are provided for the calculation of gaze angle within a virtual world using a monocular eye-tracker in a three-dimensional environment. In addition, we provide algorithms for the calculation of the angular distance between the gaze and a relevant virtual object and for the identification of fixations, saccades, and pursuit eye movements. Finally, we provide tools that temporally synchronize gaze data and the visual stimulus and enable real-time assembly of a video-based record of the experiment using the Quicktime MOV format, available at http://sourceforge.net/p/utdvrlibraries/. This record contains the visual stimulus, the gaze cursor, and associated numerical data and can be used for data exportation, visual inspection, and validation of calculated gaze movements.
Abstract In 1988 Pelli and Robson developed and produced a letter chart used to determine contras... more Abstract In 1988 Pelli and Robson developed and produced a letter chart used to determine contrast sensitivity in human subjects. An interesting and unintended phenomenon arises when one gets to the lowest-contrast letters. While at first these letters do not appear to be 'there'at all, over an extended amount of time (15–20 seconds) these letters gradually fade into appearance. This extremely long time course is unlike that of any other known mechanism involved in visual recognition. What is the nature of this mechanism and what ...
Journal of Experimental Psychology: Human Perception and Performance, 2012
People can often anticipate the outcome of another person&amp... more People can often anticipate the outcome of another person's actions based on visual information available in the movements of the other person's body. We investigated this problem by studying how goalkeepers anticipate the direction of a penalty kick in soccer. The specific aim was to determine whether the information used to anticipate kick direction is best characterized as local to a particular body segment or distributed across multiple segments. In Experiment 1, we recorded the movements of soccer players as they kicked balls into a net. Using a novel method for analyzing motion capture data, we identified sources of local and distributed information that were reliable indicators of kick direction. In Experiments 2 and 3, subjects were presented with animations of kickers' movements prior to foot-to-ball contact and instructed to judge kick direction. Judgments were consistent with the use of distributed information, with a possible small contribution of local information.
Glucose-6-phosphate dehydrogenase (G6PD) is an important site of metabolic control in the pentose... more Glucose-6-phosphate dehydrogenase (G6PD) is an important site of metabolic control in the pentose phosphate pathway (PPP), providing reducing power (NADPH) and pentose phosphates. The purpose of this study was to investigate the possible involvement of G6PD deficiency (G6PD-) in the pathogenesis of pterygium. Erythrocyte G6PD activity was evaluated in 123 pterygium patients and in 112 age-matched control patients. Enzyme activity, mRNA, rate of growth, green autofluorescence, response to oxidative stress, and cholesterol metabolism were determined in pterygium fibroblasts (PFs) and in normal conjunctival fibroblasts (NCFs) isolated from G6PD normal (NCFs+ and PFs+) and G6PD- (NCFs- and PFs-) patients. Higher prevalence of G6PD- was found in patients affected by primary pterygium than in control subjects, both men and women, suggesting that this enzymatic defect may be a predisposing factor for pterygium. G6PD activity was significantly lower in NCFs- than in NCFs+, but not in PFs- than in PFs+. In PFs-, G6PD mRNA levels were significantly higher than in PFs+. Growth-stimulated NCFs- grew at half the rate of NCFs+, although PFs- and PFs+ grew at the same rate. Increased green autofluorescence and susceptibility to oxidative stress were observed in PFs (+/-) and in NCFs-, but not in NCFs+. Moreover, ex vivo PFs (+/-) accumulated more lipids than corresponding NCFs. The results of this study, although restricted to a limited group of subjects (i.e., those of Sardinian ancestry), suggest that G6PD- not only does not protect against pterygium, but may even be considered a risk factor for the development of this disorder.
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