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C Bower

Publications and source records attributed to C Bower.

At least 19 recordsLinked to original sources
PubMed2001

Measurement of the cosmic-ray antiproton-to-proton abundance ratio between 4 and 50 GeV.

We present a new measurement of the antiproton-to-proton abundance ratio, pbar/p, in the cosmic radiation. The HEAT-pbar instrument, a balloon borne magnet spectrometer with precise rigidity and multiple energy loss measurement capability, was flown successfully in Spring 2000, at an average atmospheric depth of 7.2 g/cm(2). A total of 71 antiprotons were identified above the vertical geomagnetic cutoff rigidity of 4.2 GV. The highest measured proton energy was 81 GeV. We find that the pbar/p abundance ratio agrees with that expected from a purely secondary origin of antiprotons produced by primary protons with a standard soft energy spectrum.

Journal Article↗
PubMed2001

High critical currents in iron-clad superconducting MgB2 wires.

Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39 K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39 K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000 A cm-2 at 4.2 K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the 'weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.

Journal Article↗
PubMed2001

Optimizing effectiveness of laser tympanic membrane fenestration in chronic otitis media with effusion. Clinical and technical considerations.

OBJECTIVE: To describe the patient, disease and clinical characteristics that optimize the effectiveness of laser tympanic membrane fenestration (LTMF) to treat chronic otitis media with effusion (OME). SETTING: Four pediatric otolaryngology tertiary referral centers. IRB approved; participation by informed consent. METHODS: An observational clinical effectiveness trial was conducted in 164 ears (94 children), who had chronic OME. All patients were candidates for insertion of pressure equalization tubes (PETs) but agreed to undergo LTMF instead. Clinical and audiologic follow-up are reported at 90 days after LTMF. OUTCOME MEASURES: Clinical effectiveness was defined as an effusion free middle ear at otoscopy with A or C1 tympanogram and normal hearing. RESULTS: At 90 days, 66% of the 95 evaluable ears were effusion free, all with normal hearing. Children younger than 4 years (P<0.04), who had shorter durations of effusion (P<0.009), and who experienced longer duration of fenestration patency (FP) (P<0.009) correlated to improved outcomes. CONCLUSIONS: The use of LTMF to create 2--3 weeks of middle ear ventilation in patients with chronic OME (middle ear effusion (MEE) for 3 months or greater) is effective in 66% of 95 (58%) of ears evaluable at 90 days follow-up. This study provides basic information needed to optimize the use of LTMF today and enhance research efforts in the future.

Child↗
PubMed2001

VN training scheme.

Explore the source record for details and available documents.

Animal Technicians↗
PubMed2001

Ascertainment of pregnancies terminated because of birth defects: effect on completeness of adding a new source of data.

BACKGROUND: When evaluating preventive programs such as folate promotion and rubella vaccination, it is critically important to include terminations of pregnancy for neural tube defects and congenital rubella syndrome. Data from birth defects registries are often used for this purpose. The Western Australian Birth Defects Registry ascertains cases of birth defects in livebirths, stillbirths, and terminations of pregnancy for fetal abnormality, using multiple sources of ascertainment. METHODS: Data on terminations of pregnancy for fetal abnormality from the Western Australian Hospital Morbidity Data System 1980-1997 (not previously available to the Registry) were used to estimate the completeness of ascertainment of such cases by the Registry. Ascertainment-adjusted prevalences were calculated using capture-recapture methods. RESULTS: A total of 702 terminations with birth defects were identified among hospital discharges, most of which were already known to the Registry (87.9%). Of the 85 new cases, seven had a neural tube defect, 23 had a chromosomal defect, and 12 had confirmed maternal rubella infection during pregnancy. The ascertainment-adjusted prevalence was not importantly [corrected] different for birth defects overall or for these individual conditions, although the 95% confidence intervals for all birth defects, and for all chromosomal defects, did not include the prevalence based on registered cases only. CONCLUSIONS: The Western Australian Birth Defects Registry ascertains a high proportion of pregnancies terminated for fetal abnormality, and should therefore be a reliable source of data with which to assist in monitoring the effectiveness of preventive programs.

Abortion, Induced↗
PubMed2001

The incidence and epidemiology of congenital upper limb anomalies: a total population study.

An 11-year total population study of Western Australia examined the prevalence and epidemiology of congenital upper limb anomalies. All anomalies were classified according to the International Federation of Surgical Societies of the Hand classification. We found the prevalence of babies born with upper limb anomalies to be 1 in 506. Forty-six percent of those affected had another nonhand congenital anomaly. Fifty-one percent had bilateral hand anomalies, and 17% had multiple different hand anomalies. The most common anomalies were failures of differentiation (35%), duplications (33%), and failures of formation (15%). Congenital upper limb anomalies were more common in boys; preterm, postterm, and multiple births; and older mothers. No significant differences in prevalence or frequency of anomalies were found between whites and nonwhites, left and right sides, and in babies that survived and those who died shortly after birth.

Female↗
PubMed2001

Effectiveness of adenoidectomy and laser tympanic membrane fenestration.

OBJECTIVE: Adenoidectomy alone or with tonsillectomy (A+/-T) is an effective surgical intervention in the management of otitis media in children, especially when it is performed in conjunction with insertion of pressure equalization tubes (PETs). Otorrhea and persistent tympanic membrane (TM) perforation are frequent complications. This study evaluates the effectiveness of intermediate duration middle ear ventilation using laser tympanic membrane fenestration (LTMF) without tube insertion and as an adjunct to adenoidectomy in resolving middle ear disease within the first 90 days after surgery. STUDY DESIGN: This pilot study was a multicenter, prospective clinical cohort trial. Institutional review board approval and informed consent were obtained. The study involved four tertiary care pediatric otolaryngology departments. Fifty children (96 ears) were treated with LTMF in conjunction with A+/-T from June 1, 1998, through March 30, 1999. Ages ranged from 9 months to 12 years. Patients undergoing A+/-T who would have been recommended for PET insertion instead underwent middle ear ventilation with LTMF using the Oto-LAM device (ESC/Sharplan, Yokneam, Israel). Patients were seen at 30, 60, and 90 days postoperatively. Resolution of otitis media with effusion was determined by clinical examination, which included pneumatic otoscopy, audiometry, and tympanometry. RESULTS: Of the treated ears, 88%, 86%, and 83% had clinical resolution of middle ear disease at 30, 60, and 90 days, respectively. Preoperatively, 45% (n = 85) of ears had normal hearing; 92% (n = 49) had normal hearing at 90 days. Eighty-nine percent (n = 92) had type C2 or B tympanograms preoperatively, and 12% (n = 60) had type C2 or B at 90 days. CONCLUSION: Laser tympanic membrane fenestration in conjunction with adenoidectomy was effective in restoring normal middle ear function at 90 days post-treatment in greater than 80% of children who otherwise may have had placement of PETs.

Adenoids↗
PubMed2001

Modelling the potential impact of population-wide periconceptional folate/multivitamin supplementation on multiple births.

OBJECTIVE: To develop a model of the impact of population-wide periconceptional folate supplementation on neural tube defects and twin births. DESIGN: A hypothetical cohort of 100,000 pregnancies > or =20 weeks, plus terminations of pregnancy after prenatal diagnosis before 20 weeks. METHODS: Application of pooled data on the relative risks for neural tube defects and twins following periconceptional folate from meta-analysis of the randomised trials. MAIN OUTCOME MEASURES: 1. Pregnancies with a neural tube defect (i.e. terminations of pregnancy, perinatal deaths, and surviving infants); 2. twin births (i.e. preterm births, perinatal deaths, postneonatal deaths, birth defects, cerebral palsy); 3. numbers needed to treat. RESULTS: The change in neural tube defects would be 75 fewer terminations (95% CI -47, -90), 30 fewer perinatal deaths (95% CI 18, -35), and 13 fewer surviving infants with a neural tube defect (95% CI -8, -16). The change in twinning would be an additional 572 twin confinements (95% CI -100, +1587), among whom there would be 63 very preterm twin confinements (95% CI -11, +174), 54 perinatal and postneonatal deaths (95% CI -9, +149), 48 surviving twins with a birth defect (95% CI -8, +133), and nine with cerebral palsy (95% CI -2, +26). The numbers needed to treat for the prevention of one pregnancy with a neural tube defect is 847, for the birth of one additional set of twins is 175, for the birth of one additional set of very preterm twins is 1587, and for the birth of an additional twin with any of the following outcomes (perinatal death, postneonatal death, survival with a birth defect, or survival with cerebral palsy) is 901. CONCLUSIONS: Monitoring rates of neural tube defects and twinning is essential as supplementation or fortification with folate is implemented.

Cohort Studies↗
PubMed2000

Population screening for cystic fibrosis in Western Australia: community response.

We measured acceptance of carrier testing for cystic fibrosis in the community when offered in a primary care setting, determined variables influencing acceptance, and assessed knowledge of cystic fibrosis 3-6 months later. A total of 5,102 individuals age 18-50 years attending general practices or a family planning clinic in Western Australia completed questionnaires about knowledge of cystic fibrosis and the State Anxiety Inventory. Testing for the delta F508 gene was offered. After 3-6 months, carriers, a sample of consenting participants who were not tested, and a sample of test-negative participants were sent a further questionnaire; 43.5% of participants chose to be tested for cystic fibrosis carrier status. Women, younger people, people with higher education, people without children, and people planning to have children were more likely to be tested. After 3-6 months, carriers gave correct responses to questions about cystic fibrosis more frequently than those who tested negative or were not tested; 82.2% of carriers knew that they were definitely a carrier and 31.1% of test-negative individuals believed they were definitely not carriers. Thus, population carrier screening for cystic fibrosis offered in a community setting in Western Australia was acceptable to almost half of those offered testing, particularly younger people and those planning to have children, for whom knowledge of carrier status could be useful in making reproductive decisions. There was evidence that tested individuals recalled information in a way that minimised their risk of being a carrier.

Adolescent↗
PubMed2000

Electronic structures of single-walled carbon nanotubes determined by NMR

Single-walled carbon nanotubes were studied by (13)C nuclear magnetic resonance (NMR). Two types of (13)C nuclear spins were identified with different spin-lattice relaxation rates. The fast-relaxing component, assigned to metallic tubes, followed the relaxation behavior expected in metals, and the density-of-states at the Fermi level increased with decreasing tube diameter. The slow-relaxing component has a significantly lower density-of-states at the Fermi level. Exposure to oxygen has a substantial effect on relaxation rates of both components.

Journal Article↗
PubMed2000

Periconceptional supplementation with folate and/or multivitamins for preventing neural tube defects.

BACKGROUND: Neural tube defects arise during the development of the brain and spinal cord. OBJECTIVES: The objective of this review was to assess the effects of increased consumption of multivitamins or folate on the prevalence of neural tube defects before pregnancy and in the first two months of pregnancy (periconceptionally). SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group trials register. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing periconceptional supplementation by multivitamins with placebo, folate with placebo, or multivitamins with folate; different dosages of multivitamins or folate; prepregnancy dietary advice and counselling in primary care settings to increase the consumption of folate-rich foods, or folate-fortified foods, with standard care; increased intensity of information provision with standard public health dissemination. DATA COLLECTION AND ANALYSIS: Two reviewers assessed trial quality and extracted data. MAIN RESULTS: Four trials involving 6425 women were included. The trials all addressed the question of supplementation and they were of variable quality. No dissemination trials were identified. Periconceptional folate supplementation reduced the incidence of neural tube defects (odds ratio 0.28, 95% confidence interval 0.15 to 0.53). Folate supplementation did not significantly increase spontaneous abortion, ectopic pregnancy or stillbirth, although there was a possible increase in multiple gestation. Multivitamins alone were not associated with prevention of neural tube defects and did not produce preventive effects when given with folate. REVIEWER'S CONCLUSIONS: Periconceptional folate supplementation has a strong protective effect against neural tube defects. Information about folate should be made more widely available throughout the health and education systems. Women whose fetuses or babies have neural tube defects should be offered continuing folate supplementation. The benefits and risks of fortifying basic food stuffs, such as flour, with added folate remain unresolved.

Dietary Supplements↗
PubMed2000

Birth defects in children with newborn encephalopathy.

This study was designed to investigate birth defects found in association with newborn encephalopathy. All possible birth defects were ascertained in a population-based study of 276 term infants with moderate or severe encephalopathy and 564 unmatched term control infants. A strong association between birth defects and newborn encephalopathy was found with defects affecting 27.5% of children with encephalopathy and 4.3% of control children (odds ratio 8.55; 95% confidence interval 5.25 to 13.91;p<0.001). In 11.8% of infants with a birth defect the defect was not diagnosed until after the newborn period, illustrating one of the difficulties in attempting to exclude infants with birth defects from studies of newborn encephalopathy. The majority of defects (89%) were not specific anomalies of the CNS. In 36.8% of children with encephalopthy who had a birth defect, the defect was considered to be the probable cause of the encephalopathy. Infants with birth defects who had encephalopathy had a poorer prognosis than those without: they were twice as likely to die by the age of 2 years and three times more likely to have cerebral palsy. This study catalogues the spectrum of birth defects associated with newborn encephalopathy and illustrates the importance of their inclusion when investigating both the aetiology and outcome of this condition.

Abnormalities, Multiple↗
PubMed2000

Survival of infants born with Down's syndrome: 1980-96.

The improved life expectancy of people with Down's syndrome as a result of the greater availability of surgery and advances in medical care has been widely documented. However, there has been no evaluation of survival in the Australian Down's syndrome population since the 1980s. This study aimed to evaluate the changes in survival from birth in cases of Down's syndrome notified to the Birth Defects Registry in Western Australia. Babies born with Down's syndrome between 1980 and 1996 (inclusive) and registered with the Birth Defects Registry were studied. Survival status was obtained in several ways. Cases were stratified into three cohorts for comparison. Survival curves were constructed using the methods of Kaplan and Meier. For infants born during 1980-96, survival to 1 year is now > 91%, and 85% can expect to survive until the age of 10 years. Although survival in those with heart disease showed improvement over the period studied, overall this was still a strong predictor of mortality. Survival in Aboriginal children with Down's syndrome was significantly poorer than in non-Aboriginal children, mirroring the pattern in the general population. Mortality was greater in females and in those with a low birthweight. There was no statistically significant difference in the survival between those born in metropolitan and in rural areas. There has been a considerable improvement in survival of infants born with Down's syndrome in Western Australia. This improvement is similar to findings in recent international studies. The difference in survival between Aboriginal and non-Aboriginal children is particularly disturbing. These findings are useful for both clinicians and families who need to plan for the long-term care of these children.

Adult↗
PubMed2000

Intellectual disability in Western Australia.

OBJECTIVE: To investigate the prevalence of intellectual disability in Western Australia (WA), its causes, prevention, and trends over time. METHODOLOGY: Data from an administrative database of intellectual disability in WA were used to report on the trends in intellectual disability in childhood. RESULTS: The prevalence of intellectual disability was 8.3 per 1000 live births in 1980-90. For half the cases, there was no known cause for the intellectual disability. Down syndrome accounted for 14 to 15% of all cases. Since the introduction of newborn screening, no WA-born child participating in the screening program has been diagnosed with intellectual disability as a result of either phenylketonuria or congenital hypothyroidism. The rate of autism spectrum disorders rose from three to six per 10 000 in the 1980-83 WA birth cohort to 10-13 per 10 000 for the 1989-92 cohort. CONCLUSIONS: Recent linkage of this administrative database to the WA Maternal and Child Health Research Data Base provides a unique opportunity for more detailed investigation of intellectual disability and its risk factors in a large, well-ascertained population of children.

Autistic Disorder↗