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Biomedical subjects

S L Chuang

Publications and source records attributed to S L Chuang.

6 recordsLinked to original sources
PubMed2006

Demonstration of mode conversion in an irregular waveguide.

Communications wavelength waveguide mode conversion is demonstrated in an irregular metal-walled structure that was designed by using multiresolution optimization. Strong scatter and a large number of degrees of freedom allowed high-efficiency conversion in a device having a length of just a few wavelengths. The fabrication approach draws on standard semiconductor processing. Mode-selective reflectors, splitters, phase shifters, and other elements can be achieved by using this principle.

Journal Article↗
PubMed2001

A comparison of clinical use of fluticasone propionate and beclomethasone dipropionate in pediatric asthma.

Inhaled steroids play a very important role in the prevention and treatment of asthma. Previous studies indicated that fluticasone propionate (FP) had low bioavailability and high local potency. However, the laboratory data in these studies were not obtained among Taiwan population. It is very important that native data should be established. Thus a 12-week research program was designed, involving 77 patients, 51 for FP group and 26 for beclomethasone dipropionate (BD) group. The objects were victims of moderate to severe asthma and their age ranged from 4 to 14 years old. An open, comparative and randomized method was adopted. Except for the 4-week-later daytime symptom score(P = 0.033, BD group was better), no other significant differences were found between the two groups in the symptom score improvement(P > 0.05). All the P-values for the daytime & night-time scores were lower than 0.001, which means obvious improvement after treatment in both groups. P-value for PEF improvement was 0.003 after 4 weeks (BD group was better) and 0.943 after 8 weeks; for FEV1 improvement, it was 0.005 after 4 weeks(BD group was better) and 0.252 after 8 weeks; and for FEV1/FVC improvements, it was 0.067 after 4 weeks and 0.097 after 8 weeks. There was no statistic significance in total eosinophil count (TEC), IgE, eosinophil cationic protein (ECP) serum level changes after 4 or 8 weeks. Adverse effects were all anticipated and no statistic significance showed up, either, between the two groups or in the cortisol levels (P > 0.05). In conclusion, native data indicated that the potency of 100 micrograms of FP was equal to that of 200 micrograms of BD and that few side effects were noted in FP group. It is recommended that this drug be introduced for clinical use.

Adolescent↗
PubMed2000

Reference ranges for the linear dimensions of the intracranial ventricles in preterm neonates.

AIMS: To establish normal ranges, in preterm infants < 33 weeks' gestation, for measurements of the lateral, third, and fourth ventricles and to assess intra-observer and inter-observer reliability. To assess the effect of head position during scanning on lateral ventricle size. To determine whether sex influences ventricle size. METHODS: A prospective study involving infants < 33 weeks' gestational age (GA) at birth. Cranial ultrasound scans were done during the first 3 days of life. Linear dimensions of the anterior horn width and thalamo-occipital distance of the lateral ventricles, the width of the third ventricle, and the width and length of the fourth ventricle were measured. Measurements were plotted against GA and reference ranges produced. All measurements were tested for intra-observer and inter-observer reliability. Head position and sex differences were studied. RESULTS: 120 infants with known GA (23(+1) to 32(+6) weeks) had their intracranial ventricles measured. Reference ranges obtained were-anterior horn width: 0-2.9 mm; thalamo-occipital distance: 8.7-24.7 mm; third ventricle width: 0-2.6 mm; fourth ventricle width: 3.3-7.4 mm; fourth ventricle length: 2.6-6.9 mm. Dependent and non-dependent lateral ventricles did not differ significantly in size. There was no clinically significant difference in ventricular size between sexes. CONCLUSIONS: Reference ranges for the measurement of the intracranial ventricles in preterm infants from 23 to 33 weeks' GA are provided and can be used in the diagnosis and assessment of ventricular enlargement in preterm infants. All measurements have good intra-observer and inter-observer reliability. Head position at the time of scanning does not influence the asymmetry of the lateral ventricular measurements. The infant's sex does not influence ventricular size.

Cerebral Ventricles↗
PubMed1999

Why do preterm infants die in the 1990s?

OBJECTIVES: To describe the mortality rate for preterm infants (born 23-36 completed weeks' gestational age) and to determine the causes of death, focusing on avoidable causes. DESIGN AND SETTING: Prospective cohort study of preterm infants born at Royal Women's Hospital, Melbourne (a tertiary referral hospital with a neonatal intensive care unit and a special care nursery) from January 1994 to December 1996. SUBJECTS: 2475 consecutive liveborn infants with gestational ages from 23 to 36 weeks. MAIN OUTCOME MEASURES: Mortality rate during the primary hospitalisation, and causes of death. RESULTS: The total mortality rate was 4.8% (118/2475). The mortality rate declined with increasing maturity. The decrease in mortality was rapid between 23 and 28 weeks' gestational age, from 64.5% at 23 weeks to 4.0% at 28 weeks, then slower, falling to 0.4% at 36 weeks. Fifty of the 118 infants who died had lethal congenital anomalies. Lethal anomalies accounted for three-quarters of deaths in infants aged 28-36 weeks. The mortality rate in infants free of lethal anomalies was 2.8% (68/2425) and only 0.2% (4/1759) for infants aged 32-36 weeks. In the 68 infants without lethal anomalies who died, few obvious preventable causes were identified. CONCLUSIONS: Mortality rates fell rapidly between 23 and 28 weeks' gestational age. Survival rates for preterm infants born after 31 weeks' gestational age approached the survival rates of term infants. Lethal congenital anomalies were the most common cause of death; preventable causes of death were rare.

Australia↗
PubMed1999

Changing mortality and causes of death in infants 23-27 weeks' gestational age.

OBJECTIVE: To contrast the mortality rates and changes in the causes of death of very preterm infants (23-27 weeks), before and after the introduction of exogenous surfactant in 1991, and to identify any preventable causes of death remaining in the 1990s. METHODOLOGY: This was a cohort study on consecutive preterm infants of 23-27 weeks' gestational age born in the Royal Women's Hospital, Melbourne, a level III perinatal centre. The infants were livebirths free of lethal anomalies from two distinct eras, 1983-90, and 1992-96, inclusive. The main outcome measures were mortality during the primary hospitalization and the causes of death before and after the introduction of exogenous surfactant in 1991. RESULTS: In 1983-90, 261 of 508 livebirths (51.4%) of 23-27 weeks' gestational age died, a significantly higher proportion than the 109 of 384 (28.4%) livebirths who died in the period 1992-96. The mortality rate fell significantly with increasing gestational age and was lower at each week of gestational age in 1992-96. More infants who died in 1992-96 were treated intensively in the neonatal intensive care unit (NICU). Of the group of infants who died or who were treated intensively in NICU, respiratory causes of death predominated. However, the causes of death changed over time. In 1992-96 proportionally fewer infants died from respiratory causes (1983-90, 82.5%; 1992-96, 60.0%; odds ratio (OR) 0.31, 95%; confidence interval (CI) 0.16-0.57), but more from septic causes (1983-90, 14.3%; 1992-96, 43.8%; OR 4.9, 95%; CI 2.6-9.2). CONCLUSIONS: As the mortality rate has fallen over time, respiratory causes of death have diminished, but septic causes of death have increased. Further advances in the use of exogenous surfactant and respiratory support may reduce respiratory deaths. Effective strategies to reduce nosocomial infections are urgently required.

Cause of Death↗