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D Vishwanath

Publications and source records attributed to D Vishwanath.

5 recordsLinked to original sources
PubMed2000

Saccadic localization of occluded targets.

Saccadic eye movements are able to localize spatially-extended targets, including patterns of random dots and simple shapes, with a high degree of precision [McGowan, Kowler, Sharma & Chubb (1998). Vision Research, 38, 895-909; Melcher & Kowler (1999). Vision Research, 39, 2929-2946]. This paper investigates the representations of object shape that guide saccades. We studied saccadic localization of partially-occluded triangles (two or three vertices removed) to find out whether saccades have access to a representation of the full shape, despite the missing portions. Targets were configured so that they could be seen either as triangles, which were partially occluded by polygons, or as fragments in front of the same polygons. Subjects tried to saccade to the inferred full triangle and a discrimination paradigm was used to evaluate their success. Occlusion cues were ineffective in that saccades directed to the occluded triangles landed near the center of the visible fragment, even when it was configured as a triangle behind occluders. Removing the occluders and leaving only three segments of the triangle (vertices removed) helped somewhat, but performance never resembled that achieved with either a full triangle or a 3-dot configuration. We conclude that the saccadic system is insensitive to at least some cues that can be used to infer the shape of objects. For occluded targets, the representation used by saccades may be closer to the configuration of the retinal image.

Form Perception↗
PubMed1995

Mechanical ventilation of newborns: experience from a level II NICU.

OBJECTIVES: To analyse the indications, clinical profile, complications and outcome of the babies requiring mechanical ventilation. DESIGN: Retrospective study. SETTING: NICU of a teaching hospital. SUBJECTS: One hundred and twenty one neonates requiring assisted ventilation during three years. RESULTS: Of 121 babies 59(48.76%) survived. Hyaline membrane disease (HMD) was the commonest indication for ventilation followed by birth asphyxia, apnea of prematurity, meconium aspiration syndrome (MAS) and septicemia. Infants with HMD whose birth weight was more than 1.5 kg and those who required ventilation after 24 hours of birth had better outcome. Survival rates increased with increasing birth weight and gestational age. Prolonged ventilatory support was needed for HMD (mean 117.3 hr) and MAS (mean 82.6 hr). Pneumonia was the commonest complication, followed by sepsis, air leak syndromes and intracranial and pulmonary hemorrhage. CONCLUSIONS: Ventilatory facilities must be focussed for neonates weighing > 1000 g. Assisted ventilation may not be cost-effective in patients weighing < or = 1000 g and those with complex heart diseases and other congenital anomalies.

Cost-Benefit Analysis↗
PubMedDate not supplied

Clinical profile and management of PDA in neonates.

Patent ductus arteriosus (PDA) is recognised more often with increasing survival of preterm babies. The pharmacological closure of ductus by indomethacin has changed the management of PDA. Twenty neonates admitted over a period of 21 months to Neonatal Intensive Care Unit (NICU) of M.S. Ramaiah Medical College hospital, Bangalore, who were diagnosed to have PDA, were analyzed. The objectives of this retrospective analysis were to study the clinical profile, the efficacy of oral indomethacin and the outcome of PDA. 2-D and Doppler echocardiaography were used to confirm the clinically suspected PDA. These neonates were treated with 3 doses of oral indomethacin (0.2-0.25 mg/kg/dose 12 hourly) along with fluid restriction and oxygen. Echocardiography was repeated to demonstrate the closure of PDA. The incidence of PDA was 2.3% of total NICU admissions. Seventy percent of this cohort were < 32 weeks of gestation, 55% had birth weight of < 1500 gms. Seventy percent (14) neonates had onset of PDA after 48 hrs of life. 81.25% of neonates responded to indomethacin and overall survival rate in treated group was 67%. Drug related complications were noted in 2 newborns. This study illustrates the utility of echocardiography in diagnosing and monitoring PDA in preterm and low birth weight babies with high index of suspicion of this common congenital heart disease. Pharmacological intervention with indomethacin is rewarding with acceptable results.

Administration, Oral↗