Developmental changes in audiotactile event perception.

The fission and fusion illusions provide measures of multisensory integration. The sound-induced tap fission illusion occurs when a tap is paired with two distractor sounds, resulting in the perception of two taps; the sound-induced tap fusion illusion occurs when two taps are paired with a single sound, resulting in the perception of a single tap. Using these illusions, we measured integration in three groups of children (9-, 11-, and 13-year-olds) and compared them with a group of adults. Based on accuracy, we derived a measure of magnitude of illusion and used a signal detection analysis to estimate perceptual discriminability and decisional criterion. All age groups showed a significant fission illusion, whereas only the three groups of children showed a significant fusion illusion. When compared with adults, the 9-year-olds showed larger fission and fusion illusions (i.e., reduced discriminability and greater bias), whereas the 11-year-olds were adult-like for fission but showed some differences for fusion: significantly worse discriminability and marginally greater magnitude and criterion. The 13-year-olds were adult-like on all measures. Based on the pattern of data, we speculate that the developmental trajectories for fission and fusion differ. We discuss these developmental results in the context of three non-mutually exclusive theoretical frameworks: sensory dominance, maximum likelihood estimation, and causal inference.

The development of audio-visual temporal precision precedes its rapid recalibration.

Through development, multisensory systems reach a balance between stability and flexibility: the systems integrate optimally cross-modal signals from the same events, while remaining adaptive to environmental changes. Is continuous intersensory recalibration required to shape optimal integration mechanisms, or does multisensory integration develop prior to recalibration? Here, we examined the development of multisensory integration and rapid recalibration in the temporal domain by re-analyzing published datasets for audio-visual, audio-tactile, and visual-tactile combinations. Results showed that children reach an adult level of precision in audio-visual simultaneity perception and show the first sign of rapid recalibration at 9 years of age. In contrast, there was very weak rapid recalibration for other cross-modal combinations at all ages, even when adult levels of temporal precision had developed. Thus, the development of audio-visual rapid recalibration appears to require the maturation of temporal precision. It may serve to accommodate distance-dependent travel time differences between light and sound.

Developmental changes in the perception of audiotactile simultaneity.

We charted the developmental trajectory of the perception of audiotactile simultaneity by testing three groups of children (aged 7, 9, and 11 years) and one group of adults. A white noise burst and a tap to the index finger were presented at 1 of 13 stimulus onset asynchronies (SOAs), and the participants were asked to report whether the two stimuli were simultaneous. Compared with adults, 7-year-olds made significantly more simultaneous responses at 9 of the 13 SOAs, whereas 9-year-olds differed from adults at only 2 SOAs. The precision of simultaneity perception was lower, and response errors were higher, in younger children than in adults. The 11-year-olds were adult-like on all measures, thereby demonstrating that judgments about simultaneity for audiotactile stimuli are mature by 11 years. This developmental pattern is similar to that for simultaneity perception for visuotactile stimuli but later than that for audiovisual stimuli. The longer developmental trajectories of the perception of simultaneity between touch and vision and between touch and audition may arise from the need to coordinate and recalibrate between different reference frames and different neural transmission times in each sensory system during body growth; in addition, the ubiquity of audiovisual experience in everyday life may accelerate the development of that modality pairing.

The "fenestrated inside fenestrated" stent graft solution for therapy-resistant type Ia endoleak after fenestrated endovascular aortic aneurysm repair.

Endoleaks combined with increasing sac size following endovascular aneurysm repair require reintervention to prevent secondary aneurysm rupture. For standard infrarenal stent grafts, there are multiple treatment strategies available. However, in the presence of a fenestrated or branched stent graft, options are limited. We describe a novel challenging approach to treat a persistent type Ia endoleak by placing a second fenestrated stent graft into the pre-existing one, thus, realigning the graft and extending the proximal sealing zone.

Branch thoracic stent graft repair for arch aneurysm.

Aortic arch aneurysms involving the major vessels of the neck pose great challenges in their repair. Open repair of these aneurysms are associated with a significant morbidity and mortality. The major challenge for endovascular repair of these complex aneurysms is the maintenance of cerebral perfusion during stent implantation and long-term durability. This paper discusses preoperative planning and technical aspects to successful endovascular repair of a large aortic arch aneurysm involving the distal take-off of the left subclavian artery.

Stress and strain behaviour modelling of the carotid bifurcation.

BACKGROUND: The aim of this study is to investigate the biomechanical stress and strain behaviour within the wall of the artery and its influence on plaque formation and rupture using computational fluid dynamics (CFD). METHODS: A three-dimensional finite-element model of the carotid bifurcation was generated to analyse the wall stress and strain behaviour. Both single-layer and multilayer models were created and structural analysis was compared between these two types of models. Systolic pressure of 180 mm Hg (~24 kPa) was applied in the inner boundary of the carotid bifurcation, and CFD analysis was performed to show the wall shear stress and pressure. RESULTS: The highest wall stress was found at the carotid bifurcation. When a high blood pressure (280 mm Hg) was applied to the carotid CFD model, the results showed that the stress at the carotid bifurcation may reach the rupture value. The multilayer carotid bifurcation model behaved differently from the equivalent single-layer model, with peak stress (Von-Mises) being higher in the multilayer model. CONCLUSION: The peak stress and strain was located at the origins of the internal and external carotid arteries. Significant shearing occurred between the layers in the wall of the artery at the bifurcation. Intramural shear stress in the CFD multilayer model has potential for intramural vascular injury. This may be responsible for plaque formation, plaque rupture and an injury/healing cycle.

Outcome of endoleak following endoluminal abdominal aortic aneurysm repair.

BACKGROUND: The most important complication of endoluminal abdominal aortic aneurysm repair is endoleak, in which there is persistent blood flow outside the graft but within the aneurysm sac. Depending on endoleak type, there is an ongoing potential for aneurysm expansion or rupture. Conversely, some endoleaks may resolve spontaneously. Absolute indications for interventional management of endoleaks remain elusive due to the heterogeneous nature of leaks and uncertainty in predicting their outcome. METHODS: A retrospective review was conducted on all endoluminal graft recipients with endoleaks at Repatriation General Hospital over a 3-year period. Data were collected via a database maintained by the Department of Vascular Surgery, and hospital casenotes. RESULTS: Sixty-six patients underwent endoluminal graft insertion in the study period. Fourteen endoleaks were observed in 11 patients, representing an endoleak rate of 21.2%. There were three type I leaks and 11 type II leaks. One type I leak resolved spontaneously, one resolved immediately following interventional management, and one resolved 6 months after interventional management. Interventional treatment was undertaken in seven cases of type II leak due to increase in aneurysm diameter by 5 mm. Two type II endoleaks resolved spontaneously. Aneurysm diameter increased in two patients following radiographic resolution of their endoleaks. There were no cases of aneurysm rupture. CONCLUSIONS: Initial observation is a reasonable management option in most cases of type II endoleak, because some will spontaneously resolve during follow up. Those associated with increase in aneurysm size should undergo interventional treatment. Conservative management of type I endoleaks may be undertaken in extreme isolated cases.

Endoluminal repair of mycotic thoracic aneurysms.

PURPOSE: To report a series of endoluminally repaired mycotic thoracic aneurysms. CASE REPORTS: Four patients with presumed mycotic aneurysms of the thoracic aorta were treated with endovascular grafts owing to overly high risk for open repair. All aneurysms were successfully excluded at the initial intervention. In one case, which required endograft fenestrations for the superior mesenteric and renal arteries, the patient died 53 days after the procedure, following graft migration and occlusion of major branch vessels. The other 3 patients remain alive and well at a mean follow-up of 16 months with no signs of ongoing sepsis. CONCLUSIONS: Endoluminal repair of thoracic mycotic aneurysms is technically feasible and, in association with long-term antibiotics, offers at least temporary protection against imminent rupture.