Amphibians found in the Amazonian Savanna of the Rio Curiaú Environmental Protection Area in Amapá, Brazil

Abstract Amphibian research has grown steadily in recent years in the Amazon region, especially in the Brazilian states of Amazonas, Pará, Rondônia, and Amapá, and neighboring areas of the Guiana Shield. Even so, few data are available for the Amazonian savannas of Brazil. To contribute to the understanding of the diversity of the amphibians of these savannas, we surveyed 15 temporary ponds, six located in open areas, seven on the edge of savanna forest, and two within the forest, in the savanna of the Rio Curiaú Environmental Protection Area (EPA) in Macapá, in the state of Amapá, northern Brazil. Sampling occurred from May 2013 to August 2014 during periods when the ponds contained water. Amphibians were sampled through visual and auditory surveys conducted during both the day- and the nighttime periods on seven days each month over a total of 84 days. A total of 1574 individuals belonging to four families, 12 genera, and 28 species were recorded during the surveys. The cumulative species curve reached the asymptote, indicating that sampling effort was adequate. The number of species was 25% higher than that reported in other studies in Amazonian savannas. Twelve species were recorded for the first time in the savanna of Amapá. Lysapsus boliviana was the most common species (n = 332 of the individuals recorded). The greatest amphibian species richness found in the Rio Curiaú EPA was associated with the savanna mosaic, forest patches, lowland swamp, and temporary ponds. The results of this study contribute to the understanding of the diversity of amphibian species in the Guianan area of endemism in northern Brazil, and also the Amazonian savannas.

Sequential dependencies in the lexical decision task

Two experiments addressed whether response latency in a trial of the lexical decision task is independent of the lexical status of the item presented in the previous trial. In Exp. 1, it was found that both word and nonword responses were significantly slower when the previous trial had involved a nonword than when it had involved a word. In Exp. 2, which employed a different list composition, it was found that responses to nonwords and pseudohomophones were significantly slower when the previous trial had involved a nonword or a pseudohomophone than when it had involved a word. However, responses to words were not influenced by the nature of the previous trial. We concluded that sequential dependencies exist across consecutive trials in the lexical decision task even when there is no semantic, morphological, phonological, or orthographic relationship between the items presented during those trials.

Aging and temporal discrimination of brief auditory intervals

In a duration-discrimination experiment, young adults (mean age = 25.1), middle-aged adults (mean age = 45.5), and older adults (mean age = 64.6) were presented with two very brief auditorily marked intervals per trial, and their task was to decide which of the two was longer in duration. An adaptive psychophysical procedure was used to determine difference thresholds in relation to a constant standard interval of 50 ms. It was found that duration-discrimination performance was unaffected by age; all three age groups yielded a difference threshold of approximately 17 ms. It was concluded that the ability to discriminate durations of very brief auditory intervals appears to be based on an underlying timing mechanism that does not slow down with advancing adult age.

General slowing in semantic priming and word recognition

Analyses of lexical decision studies revealed that (a) older (O) adults' mean semantic priming effect was 1.44 times that of younger (Y) adults, (b) regression lines describing the relations between older and younger adults' latencies in related (O = 1.54 Y-112 and unrelated conditions (O = 1.50 Y-93) were not significantly different, and (c) that there was a proportional relation between older and younger adults' priming effects (O = 1.48 Y-2). Analyses of word-naming studies yielded similar results. Analyses of delayed pronunciation data (Balota & Duchek, 1988) revealed that word recognition was 1.47 times slower in older adults, whereas older adults' output processes were only 1.26 times slower. Overall, analyses of whole latencies and durations of component processes provide converging evidence for a general slowing factor of approximately 1.5 for lexical information processing.

General cognitive slowing in the nonlexical domain: an experimental validation

Older and younger adults were tested on 4 nonlexical tasks: choice reaction time, letter classification, mental rotation, and abstract matching. A positively accelerated relation was observed between older and younger adults' latencies. Consistent with general slowing, the relation observed with the same subjects in each condition was more than 3 times as precise as in a comparable meta-analysis. Further analyses compared the ability of various models to describe the present data and also to predict the data on the basis of parameters estimated from a previous meta-analysis. Compared with linear models, the information-loss and overhead models provided more accurate accounts of general cognitive slowing in the nonlexical domain.

Duration discrimination of filled and empty auditory intervals: cognitive and perceptual factors

Adult subjects were presented with two auditory stimuli per trial, and their task was to decide which of the two was longer in duration. An adaptive psychophysical procedure was used. In Experiments 1, 2, and 4, the base duration was 50 msec, whereas in Experiment 3, the base duration was 1 sec. In Experiments 1, 2, and 4, it was found that filled intervals (continuous tones) were discriminated more accurately than empty intervals (with onset and offset marked by clicks). It was concluded that this difference was perceptual rather than cognitive in nature, since performance on filled and empty intervals was not affected by increasing cognitive load in a dual-task procedure (Experiment 2) but was affected by backward masking (Experiment 4). In contrast, the results of Experiment 3 showed that duration discrimination of filled auditory intervals of longer duration was cognitively influenced, since performance was impaired by increasing cognitive load. Implications for notions of perceptual processing and timing mechanism underlying differences in duration discrimination with filled and empty intervals are discussed.

How general is general slowing? Evidence from the lexical domain

Three analyses are reported that are based on data from 19 studies using lexical tasks and a reduced version of the Hale, Myerson, and Wagstaff (1987) nonlexical data set. The results of Analysis 1 revealed that a linear function with a slope of approximately 1.5 described the relationship between the lexical decision latencies of older (65-75 years) and younger (19-29 years) adults. The results of Analysis 2, based on response latencies from 6 lexical tasks other than lexical decision, revealed a virtually identical linear relationship. In Analysis 3, it was found that performance on nonlexical tasks spanning the same range of task difficulty was described by a significantly steeper regression line with a slope of approximately 2.0. These findings suggest that although general cognitive slowing is observed in both domains, the degree of slowing is significantly greater in the nonlexical domain than in the lexical domain. In addition, these analyses demonstrate how the meta-analytic approach may be used to determine the limits to the external validity of experimental findings.

General cognitive slowing in the nonlexical domain: An experimental validation

Older and younger adults were tested on 4 nonlexical tasks: choice reaction time, letter classification, mental rotation, and abstract matching. A positively accelerated relation was observed between older and younger adults' latencies. Consistent with general slowing, the relation observed with the same subjects in each condition was more than 3 times as precise as in a comparable meta-analysis. Further analyses compared the ability of various models to describe the present data and also to predict the data on the basis of parameters estimated from a previous meta-analysis. Compared with linear models, the information-loss and overhead models provided more accurate accounts of general cognitive slowing in the nonlexical domain.

How general is general slowing? Evidence from the lexical domain

Three analyses are reported that are based on data from 19 studies using lexical tasks and a reduced version of the Hale, Myerson, and Wagstaff (1987) nonlexical data set. The results of Analysis 1 revealed that a linear function with a slope of approximately 1.5 described the relationship between the lexical decision latencies of older (65-75 years) and younger (19-29 years) adults. The results of Analysis 2, based on response latencies from 6 lexical tasks other than lexical decision, revealed a virtually identical linear relationship. In Analysis 3, it was found that performance on nonlexical tasks spanning the same range of task difficulty was described by a significantly steeper regression line with a slope of approximately 2.0. These findings suggest that although general cognitive slowing is observed in both domains, the degree of slowing is significantly greater in the nonlexical domain than in the lexical domain. In addition, these analyses demonstrate how the meta-analytic approach may be used to determine the limits to the external validity of experimental findings.

Septal geometry in the unloaded living human heart

Right ventricular loading leads to diastolic septal flattening in man without necessarily requiring right ventricular pressure to exceed left ventricular pressure. This observation suggested that the unstressed septal configuration is flat and that its normal concave shape is due to the left-to-right transseptal pressure gradient. To examine this hypothesis, we studied septal configuration by two-dimensional echocardiography in nine patients with normal global and regional left ventricular function during surgery for coronary artery disease. The transseptal pressure gradient was obtained from pulmonary capillary wedge pressure minus right atrial pressure. Measurements were obtained at control (open chest, intact pericardium [C]), with the pericardium open (OP), on cardiopulmonary bypass (CPB), and after cardiac arrest (CA). There were no changes in any measurements between C and OP or between CPB and CA. Left ventricular end-diastolic cavity area decreased from 16.5 +/- 2.1 cm2 at C to 11.1 +/- 4.5 cm2 after CPB, and further decreased to 8.9 +/- 3.5 cm2 after CA (p less than .001), yet the septum flattened, as shown by an increase in its radius of curvature from 1.7 +/- 0.5 cm during C to 2.5 +/- 0.7 cm after CPB, and to 2.9 +/- 1.0 cm after CA (p less than .001), or from 0.4 +/- 0.1 to 0.8 +/- 0.4 to 1.1 +/- 0.5 U (p less than .001) when normalized for cavity area. Diastolic transseptal pressure gradient was reduced from 4.1 +/- 2.3 mm Hg during C to 1.1 +/- 1.8 mm Hg after CPB, and to 0.5 +/- 1.4 mm Hg after CA (p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Absence of left ventricular dysfunction during acute chagasic myocarditis in the rhesus monkey

Recent studies suggest that intracellular Trypanosoma cruzi invasion with release of intracellular myocardial antigens during T. cruzi infection is crucial to the pathogenesis of chronic chagasic myocarditis. However, in areas endemic for Chagas' disease, the incidence of clinical acute chagasic myocarditis has been reported to be low among infected individuals, while the incidence of chronic chagasic myocarditis is relatively high. Thus, either acute chagasic myocarditis rarely complicates T. cruzi infection and is not important to the pathogenesis of chronic chagasic myocarditis, or acute chagasic myocarditis rarely impairs left ventricular function and therefore causes no symptoms. To investigate this question we innoculated T. cruzi from a human patient with Chagas' disease into the subconjuntivae of six rhesus monkeys (7.5 X 10(3) parasites each). Parasitemia was monitored and weekly two-dimensional echocardiograms (for determination of end-diastolic and fractional change in area, EDA and FCA) were obtained to quantify global left ventricular function for 10 weeks. Regional left ventricular function was assessed by visual analysis of two-dimensional echocardiograms. Extent of acute myocarditis was established at autopsy. All monkeys had the Romaña sign and detectable parasitemia in the second week. Parasitemia rose in all by the ninth week (mean = 1.8 X 10(5) parasites/ml); four monkeys lost weight (mean = -12%), three died, and three were killed. Two-dimensional echocardiographic EDA and FCA remained unchanged from control to the last study within 12 hr of death (EDA = 2.6 +/- 0.9 to 2.7 +/- 1.0 cm2, FCA = 80 +/- 6.8 to 74 +/- 7.6%, NS). Furthermore, regional left ventricular function remained unchanged throughout the period of study.(ABSTRACT TRUNCATED AT 250 WORDS)

Lexical access during eye fixations in reading: Effects of word-initial letter sequence

Two experiments tested the hypothesis that lexical access in reading is initiated on the basis of word-initial letter information obtainable in the parafoveal region. Eye movements were monitored while college students read sentences containing target words whose initial trigram (Experiment 1) or bigram (Experiment 2) imposed either a high or a low degree of constraint in the lexicon. In contradiction to our hypothesis, high-constraint words (e.g., DWARF) received longer fixations than did low-constraint words (e.g., CLOWN), despite the fact that high-constraint words have an initial letter sequence shared by few other words in the lexicon. Moreover, a comparison of fixation times in viewing conditions with and without parafoveal letter information showed that the amount of decrease in target fixation time due to prior parafoveal availability was the same for high-constraint and low-constraint targets. We concluded that increased familiarity of word-initial letter sequence is beneficial to lexical access and that familiarity affects the efficiency of foveal but not parafoveal processing.

Relation of mitral valve prolapse to left ventricular size in Marfan's syndrome

Sporadic recent reports suggest that mitral valve prolapse (MVP) disappears with progressive left ventricular (LV) dilatation. To test this hypothesis, we sought to determine if an inverse relation exists between MVP and LV cavity size on M-mode echocardiograms in 83 patients with Marfan's syndrome. LV end-diastolic dimensions and presence or absence of MVP were determined. Forty-six patients had MVP. Of patients with an LV end-diastolic dimension less than or equal to 5 cm, 90% had MVP; only 19% of the 32 patients with abnormally large (greater than 5.8 cm) end-diastolic dimension had MVP. The prevalence of MVP in patients with an LV end-diastolic dimension of 5.1 to 5.8 cm was 69%. Thus, the prevalence of MVP was inversely related to LV cavity size. To determine whether appearance or disappearance of MVP was associated with decrease or increase in LV cavity size, serial echocardiograms from 67 patients (mean follow-up 42 months, range 3 to 99) were examined. These patients were separated into 3 groups based on changes in the LV end-diastolic dimension of greater than 1 cm over time. Group 1 consisted of 9 patients, all of whom had MVP and normal LV cavity size on their initial study. With subsequent increase in LV end-diastolic dimension (mean 1.42 +/- 0.3), MVP disappeared in 6 of the 9. Conversely, group 2 consisted of 4 patients, all of whom had dilated left ventricles on their initial echocardiogram and no evidence of MVP. After aortic valve replacement, the LV cavity size decreased (mean 2.3 +/- 0.7) and MVP appeared on follow-up studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous mitral valve prolapse in a breeding colony of rhesus monkeys

Mitral valve prolapse was observed in 26 of 92 animals in a harem breeding colony of rhesus monkeys (Macaca mulatta). The affected animals had a systolic murmur best auscultated over the mitral region with the animal in a sitting position. Mid-to-late systolic clicks were also heard. Phonocardiographic examination also demonstrated systolic murmurs and clicks in six of 16 animals. Twenty-three of the animals were studied by M mode and/or two-dimensional echocardiography. The diagnosis was confirmed in 12 animals that had a murmur during the examination. Electrocardiograms revealed T wave abnormalities in five animals and left or right ventricular hypertrophy in five. Four adult animals that died during the course of the study were confirmed at necropsy as having prolapse of the posterior and/or anterior mitral valve leaflets into the atrium. Analysis of the breeding records suggested that mitral valve prolapse was a dominant genetic trait with an approximate birth incidence of 16% to 20% in the colony. The existence of mitral valve prolapse in a nonhuman primate species provides a unique opportunity to study the disease in an experimental animal.