Composição e diversidade de serpentes em um mosaico de habitats no município de Urbano Santos, Maranhão

Este estudo apresenta os resultados de um ano de observações de campo para amostragens da fauna de serpentes em um mosaico de habitats, abrangendo matas de terra firme e inundável, plantações de eucalipto e áreas abertas, na Fazenda Santo Amaro, Município de Urbano Santos, Maranhão. A região é dominada por vegetação de Cerrado e possui clima tropical rnegatérmico, com total pluviométrico anual em torno de 1800-mm. O ano de estudo (2001) apresentou-se mais seco que a média anual, com 1197,5mm. As amostragens foram realizadas durante 24 excursões quinzenais, com duração de quatro dias cada, entre janeiro e dezembro de 2001. Estas amostragens totalizaram 768h/observador de procuras visuais diurnas e noturnas, onde os diferentes habitats foram amostrados por sorteios randomizados, nos diversos horários do dia, obtendo o mesmo número de horas de amostragem nas diferentes épocas do ano. Foram capturadas 114 serpentes, representadas por seis famílias, vinte e sete gêneros e trinta e duas espécies. Para cada espécie são apresentadas informações sobre o tamanho, período de atividade, classe etária, habitat e microhabitat. Das 32 espécies amostradas na área seis foram registradas pela primeira vez para o Maranhão como, Apostolepis cearensis, Helicops leopardinus, Oxyrhopus trigeminus, Psornophis joberti, Waglerophis merremii e Micrurus ibiboboca, Em geral, a maioria das espécies registradas tem distribuição Amazônica. Entre as espécies da área, 40,1% foram arborícolas, 25% fossóreas/criptozóicas, 21,9% terrícolas e 12,5% aquáticas, embora algumas espécies ocuparam mais de um microhabitat. A maioria das espécies ocorreu nos ambientes de mata de terra firme, mata inundável e área aberta. A similaridade entre os habitats da área, de modo geral, foi muito baixa, sendo que apenas a mata de terra firme e área aberta tiveram mais de 60% de espécies em comum. A menor complementariedade de fauna ocorreu entre os habitats "mata de terra firme" e "área aberta" e "mata inundável" e "área aberta". Em relação a outras áreas a maior similaridade entre as áreas ocorreu com as serras e maciços do Estado do Ceará. A riqueza estimada para a área, segundo os índices e estimadores utilizados nas análises, indicam que o número de espécies observadas está abaixo do estimado, que variou entre 38 (bootstrap) e 58 (Chao 2) espécies. Esses resultados representam uma primeira contribuição sobre a diversidade de serpentes na região e oferece subsídios para possíveis programas de monitoramento da fauna de serpentes e da situação dos habitats na área.

Couve consorciada com sorgo e feijão-guandu na ocorrência de pulgões e insetos predadores

Pós-graduação em Agronomia (Entomologia Agrícola) - FCAV

Effetti dell'integrazione visuo-acustica in pazienti con disturbo di campo visivo

Human brain is provided with a flexible audio-visual system, which interprets and guides responses to external events according to spatial alignment, temporal synchronization and effectiveness of unimodal signals. The aim of the present thesis was to explore the possibility that such a system might represent the neural correlate of sensory compensation after a damage to one sensory pathway. To this purpose, three experimental studies have been conducted, which addressed the immediate, short-term and long-term effects of audio-visual integration on patients with Visual Field Defect (VFD). Experiment 1 investigated whether the integration of stimuli from different modalities (cross-modal) and from the same modality (within-modal) have a different, immediate effect on localization behaviour. Patients had to localize modality-specific stimuli (visual or auditory), cross-modal stimulus pairs (visual-auditory) and within-modal stimulus pairs (visual-visual). Results showed that cross-modal stimuli evoked a greater improvement than within modal stimuli, consistent with a Bayesian explanation. Moreover, even when visual processing was impaired, cross-modal stimuli improved performance in an optimal fashion. These findings support the hypothesis that the improvement derived from multisensory integration is not attributable to simple target redundancy, and prove that optimal integration of cross-modal signals occurs in processing stage which are not consciously accessible. Experiment 2 examined the possibility to induce a short term improvement of localization performance without an explicit knowledge of visual stimulus. Patients with VFD and patients with neglect had to localize weak sounds before and after a brief exposure to a passive cross-modal stimulation, which comprised spatially disparate or spatially coincident audio-visual stimuli. After exposure to spatially disparate stimuli in the affected field, only patients with neglect exhibited a shifts of auditory localization toward the visual attractor (the so called Ventriloquism After-Effect). In contrast, after adaptation to spatially coincident stimuli, both neglect and hemianopic patients exhibited a significant improvement of auditory localization, proving the occurrence of After Effect for multisensory enhancement. These results suggest the presence of two distinct recalibration mechanisms, each mediated by a different neural route: a geniculo-striate circuit and a colliculus-extrastriate circuit respectively. Finally, Experiment 3 verified whether a systematic audio-visual stimulation could exert a long-lasting effect on patients’ oculomotor behaviour. Eye movements responses during a visual search task and a reading task were studied before and after visual (control) or audio-visual (experimental) training, in a group of twelve patients with VFD and twelve controls subjects. Results showed that prior to treatment, patients’ performance was significantly different from that of controls in relation to fixations and saccade parameters; after audiovisual training, all patients reported an improvement in ocular exploration characterized by fewer fixations and refixations, quicker and larger saccades, and reduced scanpath length. Similarly, reading parameters were significantly affected by the training, with respect to specific impairments observed in left and right hemisphere–damaged patients. The present findings provide evidence that a systematic audio-visual stimulation may encourage a more organized pattern of visual exploration with long lasting effects. In conclusion, results from these studies clearly demonstrate that the beneficial effects of audio-visual integration can be retained in absence of explicit processing of visual stimulus. Surprisingly, an improvement of spatial orienting can be obtained not only when a on-line response is required, but also after either a brief or a long adaptation to audio-visual stimulus pairs, so suggesting the maintenance of mechanisms subserving cross-modal perceptual learning after a damage to geniculo-striate pathway. The colliculus-extrastriate pathway, which is spared in patients with VFD, seems to play a pivotal role in this sensory compensation.

Lateralization of cognitive functions after stroke in childhood

A child's brain shows a remarkable ability to recover from adverse events such as stroke. Language functions recover particularly well, while visuo-spatial skills are more affected by brain damage, regardless of its localization. This study investigated the lateralization of language and visual search after childhood stroke.

The Effects of Emotions and Distraction on Attention During a Perceptual Task

According to the broaden-and-build theory of positive emotions, positive emotions broaden while negative emotions narrow thought-action repertoires. These processes reflect changes in attentional scope, which is the focus of this research. The present study tested the hypothesis that participants in negative mood would be better able to focus on a target figure and separate it from its context in a perceptual task, and would also be better able to focus on the task amid a distracting environment than participants in a positive mood. An undergraduate sample of 77 participants watched video clips selected to induce either fear or amusement, and completed an Embedded Figures Test either in a quiet setting or in a noisy setting. A higher-order ANOVA revealed that Mood had a marginally significant effect on task performance, F(1, 73) = 3.94, p = .051, and that Distraction, F(1, 72) = 4.61, p = .035 and the Mood x Distraction interaction, F(1, 73) = 9.12, p = .003 did significantly affect task performance. However, contrary to the hypothesis, the effect of the distraction manipulation was greater for participants in a negative mood than it was for participants in a positive mood. The author suggests future directions to clarify the relationship between emotions, attentional scope, and susceptibility to environmental distraction.

Strengthening of laterality of verbal and visuospatial functions during childhood and adolescence

Cognitive functions in the child's brain develop in the context of complex adaptive processes, determined by genetic and environmental factors. Little is known about the cerebral representation of cognitive functions during development. In particular, knowledge about the development of right hemispheric (RH) functions is scarce. Considering the dynamics of brain development, localization and lateralization of cognitive functions must be expected to change with age. Twenty healthy subjects (8.6-20.5 years) were examined with fMRI and neuropsychological tests. All participants completed two fMRI tasks known to activate left hemispheric (LH) regions (language tasks) and two tasks known to involve predominantly RH areas (visual search tasks). A laterality index (LI) was computed to determine the asymmetry of activation. Group analysis revealed unilateral activation of the LH language circuitry during language tasks while visual search tasks induced a more widespread RH activation pattern in frontal, superior temporal, and occipital areas. Laterality of language increased between the ages of 8-20 in frontal (r = 0.392, P = 0.049) and temporal (r = 0.387, P = 0.051) areas. The asymmetry of visual search functions increased in frontal (r = -0.525, P = 0.009) and parietal (r = -0.439, P = 0.027) regions. A positive correlation was found between Verbal-IQ and the LI during a language task (r = 0.585, P = 0.028), while visuospatial skills correlated with LIs of visual search (r = -0.621, P = 0.018). To summarize, cognitive development is accompanied by changes in the functional representation of neuronal circuitries, with a strengthening of lateralization not only for LH but also for RH functions. Our data show that age and performance, independently, account for the increases of laterality with age.

ANIMATED TRANSITION IN SIMILARITY-BASED TILED IMAGE LAYOUT

Effective techniques for organizing and visualizing large image collections are in growing demand as visual search gets increasingly popular. iMap is a treemap representation for visualizing and navigating image search and clustering results based on the evaluation of image similarity using both visual and textual information. iMap not only makes effective use of available display area to arrange images but also maintains stable update when images are inserted or removed during the query. A key challenge of using iMap lies in the difficult to follow and track the changes when updating the image arrangement as the query image changes. For many information visualization applications, showing the transition when interacting with the data is critically important as it can help users better perceive the changes and understand the underlying data. This work investigates the effectiveness of animated transition in a tiled image layout where the spiral arrangement of the images is based on their similarity. Three aspects of animated transition are considered, including animation steps, animation actions, and flying paths. Exploring and weighting the advantages and disadvantages of different methods for each aspect and in conjunction with the characteristics of the spiral image layout, we present an integrated solution, called AniMap, for animating the transition from an old layout to a new layout when a different image is selected as the query image. To smooth the animation and reduce the overlap among images during the transition, we explore different factors that might have an impact on the animation and propose our solution accordingly. We show the effectiveness of our animated transition solution by demonstrating experimental results and conducting a comparative user study.

A systematic review of the clinical performance of CAD/CAM single-tooth restorations

PURPOSE: This systematic review sought to determine the long-term clinical survival rates of single-tooth restorations fabricated with computer-aided design/computer-assisted manufacture (CAD/CAM) technology, as well as the frequency of failures depending on the CAD/CAM system, the type of restoration, the selected material, and the luting agent. MATERIALS AND METHODS: An electronic search from 1985 to 2007 was performed using two databases: Medline/PubMed and Embase. Selected keywords and well-defined inclusion and exclusion criteria guided the search. All articles were first reviewed by title, then by abstract, and subsequently by a full text reading. Data were assessed and extracted by two independent examiners. The pooled results were statistically analyzed and the overall failure rate was calculated by assuming a Poisson-distributed number of events. In addition, reported failures were analyzed by CAD/CAM system, type of restoration, restorative material, and luting agent. RESULTS: From a total of 1,957 single-tooth restorations with a mean exposure time of 7.9 years and 170 failures, the failure rate was 1.75% per year, estimated per 100 restoration years (95% CI: 1.22% to 2.52%). The estimated total survival rate after 5 years of 91.6% (95% CI: 88.2% to 94.1%) was based on random-effects Poisson regression analysis. CONCLUSIONS: Long-term survival rates for CAD/CAM single-tooth Cerec 1, Cerec 2, and Celay restorations appear to be similar to conventional ones. No clinical studies or randomized clinical trials reporting on other CAD/CAM systems currently used in clinical practice and with follow-up reports of 3 or more years were found at the time of the search.

In your eyes only: deficits in executive functioning after frontal TMS reflect in eye movements

This study investigated the roles of the right and left dorsolateral prefrontal (rDLPFC, lDLPFC) and the medial frontal cortex (MFC) in executive functioning using a theta burst transcranial magnetic stimulation (TMS) approach. Healthy subjects solved two visual search tasks: a number search task with low cognitive demands, and a number and letter search task with high cognitive demands. To observe how subjects solved the tasks, we assessed their behavior with and without TMS using eye movements when subjects were confronted with specific executive demands. To observe executive functions, we were particularly interested in TMS-induced changes in visual exploration strategies found to be associated with good or bad performance in a control condition without TMS stimulation. TMS left processing time unchanged in both tasks. Inhibition of the rDLPFC resulted in a decrease in anticipatory fixations in the number search task, i.e., a decrease in a good strategy in this low demand task. This was paired with a decrease in stimulus fixations. Together, these results point to a role of the rDLPFC in planning and response selection. Inhibition of the lDLPFC and the MFC resulted in an increase in anticipatory fixations in the number and letter search task, i.e., an increase in the application of a good strategy in this task. We interpret these results as a compensatory strategy to account for TMS-induced deficits in attentional switching when faced with high switching demands. After inhibition of the lDLPFC, an increase in regressive fixations was found in the number and letter search task. In the context of high working memory demands, this strategy appears to support TMS-induced working memory deficits. Combining an experimental TMS approach with the recording of eye movements proved sensitive to discrete decrements of executive functions and allows pinpointing the functional organization of the frontal lobes.

Clinical Performance of Screw- Versus Cement-Retained Fixed Implant-Supported Reconstructions- A Systematic Review.

PURPOSE To assess the survival outcomes and reported complications of screw- and cement-retained fixed reconstructions supported on dental implants. MATERIALS AND METHODS A Medline (PubMed), Embase, and Cochrane electronic database search from 2000 to September 2012 using MeSH and free-text terms was conducted. Selected inclusion and exclusion criteria guided the search. All studies were first reviewed by abstract and subsequently by full-text reading by two examiners independently. Data were extracted by two examiners and statistically analyzed using a random effects Poisson regression. RESULTS From 4,324 abstracts, 321 full-text articles were reviewed. Seventy-three articles were found to qualify for inclusion. Five-year survival rates of 96.03% (95% confidence interval [CI]: 93.85% to 97.43%) and 95.55% (95% CI: 92.96% to 97.19%) were calculated for cemented and screw-retained reconstructions, respectively (P = .69). Comparison of cement and screw retention showed no difference when grouped as single crowns (I-SC) (P = .10) or fixed partial dentures (I-FDP) (P = .49). The 5-year survival rate for screw-retained full-arch reconstructions was 96.71% (95% CI: 93.66% to 98.31). All-ceramic reconstruction material exhibited a significantly higher failure rate than porcelain-fused-to-metal (PFM) in cemented reconstructions (P = .01) but not when comparing screw-retained reconstructions (P = .66). Technical and biologic complications demonstrating a statistically significant difference included loss of retention (P ≤ .01), abutment loosening (P ≤ .01), porcelain fracture and/or chipping (P = .02), presence of fistula/suppuration (P ≤ .001), total technical events (P = .03), and total biologic events (P = .02). CONCLUSIONS Although no statistical difference was found between cement- and screw-retained reconstructions for survival or failure rates, screw-retained reconstructions exhibited fewer technical and biologic complications overall. There were no statistically significant differences between the failure rates of the different reconstruction types (I-SCs, I-FDPs, full-arch I-FDPs) or abutment materials (titanium, gold, ceramic). The failure rate of cemented reconstructions was not influenced by the choice of a specific cement, though cement type did influence loss of retention.

Varying expectancies and attention bias in phobic and non-phobic individuals.

Phobic individuals display an attention bias to phobia-related information and biased expectancies regarding the likelihood of being faced with such stimuli. Notably, although attention and expectancy biases are core features in phobia and anxiety disorders, these biases have mostly been investigated separately and their causal impact has not been examined. We hypothesized that these biases might be causally related. Spider phobic and low spider fearful control participants performed a visual search task in which they specified whether the deviant animal in a search array was a spider or a bird. Shorter reaction times (RTs) for spiders than for birds in this task reflect an attention bias toward spiders. Participants' expectancies regarding the likelihood of these animals being the deviant in the search array were manipulated by presenting verbal cues. Phobics were characterized by a pronounced and persistent attention bias toward spiders; controls displayed slower RTs for birds than for spiders only when spider cues had been presented. More important, we found RTs for spider detections to be virtually unaffected by the expectancy cues in both groups, whereas RTs for bird detections showed a clear influence of the cues. Our results speak to the possibility that evolution has formed attentional systems that are specific to the detection of phylogenetically salient stimuli such as threatening animals; these systems may not be as penetrable to variations in (experimentally induced) expectancies as those systems that are used for the detection of non-threatening stimuli. In sum, our findings highlight the relation between expectancies and attention engagement in general. However, expectancies may play a greater role in attention engagement in safe environments than in threatening environments.

Snakes and cats in the flower bed: Fast detection is not specific to pictures of fear-relevant animals

The observation that snakes and spiders are found faster among flowers and mushrooms than vice versa and that this search advantage is independent of set size supports the notion that fear-relevant stimuli are processed preferentially in a dedicated fear module. Experiment I replicated the faster identification of snakes and spiders but also found a set size effect in a blocked, but not in a mixed-trial, sequence. Experiment 2 failed to find faster identification of snake and spider deviants relative to other animals among flowers and mushrooms and provided evidence for a search advantage for pictures of animals, irrespective of their fear relevance. These findings suggest that results from the present visual search task cannot support the notion of preferential processing of fear relevance.

Acquisition of negative valence and modified attentional processing by non fear relevant stimuli

The current research examined valence and attentional processing of a priori fear relevant stimuli and investigated the extent to which these characteristics can be acquired by non fear relevant stimuli across an aversive learning episode. The first experiment compared pictures of snakes and spiders with pictures of birds and fish using affective priming, visual search and detection of a dot probe. Snakes and spiders were more negative than birds and fish as indexed by affective priming, and were preferentially attended to in the visual search task. The second experiment exposed the non fear relevant animal pictures, birds and fish, in an aversive learning episode involving an aversive shock US. Skin conductance responding was measured during acquisition. After acquisition, conditioned non fear relevant animal stimuli, CS1, and non conditioned, non fear relevant animal stimuli, CS, were compared across affective priming, visual search and dot probe tasks. During acquisition, skin conductance responses were larger during CS1 than during CS across all three response intervals. After acquisition, CS1 non fear relevant animal pictures were more negative than CS non fear relevant animal pictures as indexed by affective priming, and were preferentially attended to in a dot probe task. These studies provide evidence that negative valence and modified attentional processing can be acquired in a brief aversive learning episode.

Ophthalmic factors in dyslexia

Although the role of ophthalmic factors in dyslexia remains the subject of controversy, recent research has indicated that the correlates of dyslexia may include binocular dysfunction, unstable motor ocular dominance, a deficit of the transient visual subsystem, and an anomaly that can be treated with tinted lenses. These features, typically, have been studied in isolation and their inter-relationship has received little attention. The aim of the present research was to investigate ophthalmic factors in dyslexia, with a particular emphasis on the interaction between optometric variables. Further aims were to establish the most appropriate investigative techniques for optometric practice and to explore the relationship between optometric and psychometric variables. A pilot study was used to refine the experimental design for a subsequent detailed study of 39 children with a specific reading disability and 43 good readers, who were selected from 240 children. The groups were matched for age, sex, and performance IQ. The following factors emerged as correlates of dyslexia: slight impaired visual acuity; reduced vergence amplitudes; increased vergence instability; decreased accommodative amplitude; poor peformance at tests that were designed to assess the function of the transient visual system; and slightly slower performance at a non-verbal simulated reading visual search task. The `transient system deficit', as measured by reduced flicker sensitivity, was significantly associated with decreased accommodative and vergence amplitudes. This links the motor and sensory visual correlates of dyslexia. Although the binocular dysfunction was correlated with increased symptoms, the difference in the groups' simulated reading visual search task performance was largely attributable to psychometric variables. The results suggest tht optometric problems may be a contributory factor in dyslexia, but are unlikely to play a key causative role. Several optometric variables were confounded by psychometric parameters, and this interaction should be a priority for future investigation.

To which extent can attention and/or modulation explains deficits in dyslexia?

This thesis investigates the visual deficits associated with developmental dyslexia, particularly that of visual attention. Visual attention has previously been investigated in a wide array of behavioural and psychophysical (amongst others) studies but not many have produced consistent findings. Attention processes are believed to play an integral part in depicting the overall "extent" of reading deficits in dyslexia, so it was of paramount importance to aim at such attention mechanisms in this research. The experiments in this thesis focused on signal enhancement and noise (distractor) exclusion. Given the flexibility of the visual search paradigms employed in this research, factors such as visual crowding and attention distribution was also investigated. The experiments systematically manipulated noise (by increasing distractor count, i.e. set-size), crowding (varying the spacing between distractors), attention allocation (use of peripheral cues to direct attention), and attention distribution (influence of one visual field over the other), all of which were tied to a critical factor, the "location/spatial/decisional uncertainty". Adults with dyslexia were: (i) able to modulate attention appropriately using peripheral pre-cues, (ii) severely affected by crowding, and (iii) unable to counteract increased set-sizes when post or un-cued, the latter signifying poor distractor (noise) suppression. By controlling for location uncertainty, the findings confirmed that adults with dyslexia were yet again affected by crowding and set-size, in addition to an asymmetric attention distribution. Confounding effects of ADHD symptoms did not explain a significant independent variance in performance, suggesting that the difficulty shown by adult dyslexics were not accounted for by co-morbid ADHD. Furthermore, the effects of crowding, set-size and asymmetric attention correlated significantly with literacy, but not ADHD measures. It is believed that a more diffuse and an asymmetric attention system (in dyslexia) to be the limiting factor concerning noise exclusion and attention distribution. The findings from this thesis add to the current understanding of the potential role of deficits in visual attention in dyslexia and in the literacy difficulties experienced by this population.