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  • 1995-1999  (8)
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Material
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Index of refraction of GaAs/AlxGa1−xAs multiple quantum wells with an applied electric field using the grating coupling technique (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1747-1752 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The grating coupling technique is used to determine the index of refraction under an applied electric field. Light is coupled into a GaAs/AlxGa1−xAs multiple quantum well slab waveguide using a conducting grating which has been etched onto the waveguide. The coupling angle is measured with high precision and the effective index of the mode is calculated with the mode coupling equation. The technique is very sensitive, allowing the index to be determined to within ±2×10−5. The strong absorption of the quantum wells prevents measurements at photon energies near the quantum well absorption peaks. This is not a serious limitation as the measurable range is the most technologically important region for electro-optic devices which utilize refractive index changes. The linear and quadratic electro-optic coefficients, evaluated from the change in index with electric field, agree well with previous measurements by other methods. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358868
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  • 2
    Electronic Resource
    Electronic Resource
    The quantification of mortality resulting from the regular use of illicit opiates (1999)
    Oxford, UK : Carfax Publishing Limited
    Addiction 94 (1999), S. 0 
    Details
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aims/Design. Estimates of mortality associated with illicit opiate use provide useful information to those directing and monitoring local, national and international policies and programmes. Most studies investigating the association have, however, been small with imprecise estimates of increased mortality. The current study combines data from a number of international studies in a meta-analysis to estimate more precisely mortality associated with illicit opiate use. Because HIV infection among injecting drug users differs dramatically between countries and localities, we excluded studies where AIDS was a major contributor to mortality. Studies were included only where AIDS-specific mortality accounted for less than 2% of total mortality. Findings. Our results show a mortality rate for people regularly using illicit opiates, which is more than 13 times greater than that observed for the general community. It is estimated that 9.4% of total mortality in Australians aged 15-39 years of age can be attributed to regular use of illicit opiates. Application of this aetiological fraction to Australian mortality data for 1992 indicate that approximately 401 male and 161 female deaths occurred as a result of opiate use. This represents some 15 429 and 6261 person-years of life lost (to age 70) for males and females, respectively. Conclusions. The mortality rate for illicit opiate users is approximately 13 times greater than for the general population. The large number of years of life lost is reflective of the relatively young population (15-39 years of age) in which opiate-related mortality occurs. Relative risk estimates can also be applied to data on the prevalence of illicit opiate use in other countries to produce locally based aetiological fractions and estimates of person-years of life lost.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1360-0443.1999.9422216.x
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  • 3
    Electronic Resource
    Electronic Resource
    Assessing the relationship between maternal opiate use and neonatal mortality (1998)
    Oxford, UK : Carfax Publishing Limited
    Addiction 93 (1998), S. 0 
    Details
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aims/Design. We undertook a number of meta-analyses to estimate more precisely the relationship between neonatal mortality and use of opiates in three groups of women. First, women who continued to use illicit heroin throughout pregnancy; secondly, women stabilized on methadone at the time of conception or shortly after and thirdly, women who use heroin well into pregnancy with late entry into methadone treatment, or who continued to use illicit heroin during pregnancy while receiving methadone. Findings. The pooled estimates of the relative risks of neonatal mortality for separate heroin and methadone use were both near unity: 1.47 (95% CI 0.88-2.33) and 1.75 (95% CI 0.60-4.59), respectively. The result for heroin may be due to the inclusion in the meta-analysis of a particularly large study, which, unlike the two other smaller studies included, found a relative risk near unity. When this study was excluded from the meta-analysis the pooled estimate of the relative risk of neonatal mortality for heroin use was 3.27 (95% CI 0.95-9.60). In contrast to the results for use of methadone only, the pooled relative risk associated with heroin and methadone use was 6.37 (95% CI 2.57-14.68). Conclusions. The increased relative risk for neonatal mortality associated with women using heroin and methadone during pregnancy, compared to those stabilized on methadone, is probably due to the chaotic and high-risk life-style associated with illicit heroin use and not solely to the use of heroin and methadone per se. It is recommended that women who use heroin well into pregnancy with late entry into methadone treatment, or who continue to use illicit heroin during pregnancy while receiving methadone, receive special attention over and above that provided to women stabilized on methadone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1360-0443.1998.93710338.x
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  • 4
    Electronic Resource
    Electronic Resource
    Assessing the relationship between maternal cocaine use and abruptio placentae (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Addiction 92 (1997), S. 0 
    Details
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Abruptio placentae during pregnancy can result in significant morbidity and mortality to both mother and infant. A comprehensive literature search of publications from 1966 to April 1995 identified 11 studies on the association between maternal cocaine use and abruptio placentae. Their results were combined in a meta-analysis. The pooled odds ratio for abruptio placentae and maternal cocaine use was 3.92 (95% confidence interval 2.77-5.46). The strength and consistency of the association, its biological plausibility and the results of experimental studies in animals all suggest that cocaine use during pregnancy causes abruptio placentae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1360-0443.1997.tb02874.x
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  • 5
    Electronic Resource
    Electronic Resource
    Maternal cannabis use and birth weight: a meta-analysis (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Addiction 92 (1997), S. 0 
    Details
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aims. To estimate the effect of maternal cannabis use on birth weight. Design. Meta-analysis of published observational studies adjusted for cigarette smoking. Separate analyses were performed for studies of low birth weight and mean birth weight. We used fixed and random effects models, but in all cases the results were identical. Setting. From the Medline database, we identified 10 studies in which the results were adjusted for cigarette smoking. In seven studies, information on cannabis use was collected prenatally. Five studies reported results for differences in mean birth weight associated with maternal cannabis use. Participants. 32 483 women giving birth to live-bom infants. Measurements. Mean birth weight and odds ratio for low birth weight. Findings. Three analyses of the studies on mean birth weight were conducted to avoid double-counting women from one study. The largest reduction in mean birth weight for any cannabis use during pregnancy was 48 g (95% confidence interval (CI) 83-14 g), with considerable heterogeneity among the five studies. Mean birth weight was increased by 62 g (95% CI 8 g reduction-132 g increase; p heterogeneity 0.59) among infrequent users (〈inlineGraphic alt="geqslant R: gt-or-equal, slanted" extraInfo="nonStandardEntity" href="urn:x-wiley:09652140:ADD1553:ges" location="ges.gif"/〉weekly) whereas cannabis use at least four times per week had a 131 g reduction in mean birth weight (95% CI 52-209 g reduction; p heterogeneity 0.25). From the five studies of low birth weight, the pooled odds ratio for any use was 1.09 (95% CI 0.94-1.27, p heterogeneity 0.19). Conclusions. There is inadequate evidence that cannabis, at the amount typically consumed by pregnant women, causes low birth weight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1360-0443.1997.tb02875.x
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  • 6
    Electronic Resource
    Electronic Resource
    Maternal cocaine use and low birth weight newborns: a meta-analysis (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Addiction 92 (1997), S. 0 
    Details
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aim/design. Many epidemiological studies published on the association between maternal cocaine/crack use and birth weight have either lacked precision or failed to control for major confounding, predominantly by tobacco smoking. Meta-analysis enables a single summary measure of effect to be calculated by combining data from any number of individual studies, thus enhancing statistical power. We undertook a number of meta-analyses using only studies that had adjusted for tobacco smoking to estimate more precisely the effect of maternal cocaine use on birth weight. Findings. A meta-analysis of five studies presenting data for ‘any’ prenatal cocaine exposure, adjusted far tobacco smoking but unadjusted for gestational age, produced a pooled relative risk estimate from a fixed effects analysis of 2.15 (95% CI 1.75-2.64). However, there was substantial heterogeneity among studies (p 〈 0.001), and the relative risk from a random effects analysis was smaller (1.65) with a confidence interval that included unity (95% CI 0.94-2.83). Addition of a further study adjusted for gestational age had minimal effect on the pooled estimate: the fixed effects relative risk was 2.14 (1.77-2.60) and the random effects estimate 1.77 (1.15-2.71). When data on more intense prenatal exposure were analysed, the fixed and random effects analysis produced the lame pooled estimate of the relative risk of 4.42 (2.24-8.71), suggesting that more frequent cocaine exposure was associated with a higher relative risk for low birth weight. Data from studies on mean reduction in birth weight produced a pooled estimate of 112 g (95% CI 62-161 g). Conclusions. The current study suggests that maternal cocaine use causes low birth weight, and that the effect is greater with heavier use. However, despite the adjustment for tobacco and the adjustment by some studies for other confounders such as race, maternal age, gravidity and socio-economic status, it could be argued that other life-style factors not controlled for may account for the observed effects. While this argument is not supported by some other types of study, the issue of residual confounding can only be finally addressed by analytical studies which adequately control for important variables.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1360-0443.1997.tb02876.x
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  • 7
    Electronic Resource
    Electronic Resource
    The relationship between maternal use of heroin and methadone and infant birth weight (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Addiction 92 (1997), S. 0 
    Details
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aims/design. Reduction in mean birth weight and increased incidence of low birth weight are both associated with exposure to illicit heroin in pregnancy. Many studies examining neonatal outcomes in pregnant heroin users treated with methadone report improvements in birth weight. As a consequence, methadone treatment has become the ‘gold standard’ for the management of the pregnant heroin user. However, not all studies report significant birth weight increases associated with methadone. We undertook a number of meta-analyses on reduction in mean birth weight, and incidence of low birth weight to estimate more precisely the effect of illicit heroin and methadone. Findings. Results showed mean reductions in birth weight associated with heroin use: 489 g (95% CI 284-693 g), compared with methadone: 279 g (229-328 g). Similarly, the pooled relative risk estimate for low birth weight for maternal heroin use was 4.61 (95% CI 2.78-7,65), compared with 1.36 (0.83-2.22) for methadone. Analysis of data on combined heroin and methadone use produced a pooled mean reduction in birth weight of 557 g (403-710 g), with a pooled relative risk estimate for low birth weight of 3.28 (2.47-4.39). Pooling ‘any’ methadone data, regardless of heroin use, produced an estimated reduction in birth weight of 395 g (311-478 g) and a relative risk estimate for low birth weight of 1.90 (1.29-2.81). Combining all data in an ‘any’ opiate use analysis also produced a mean reduction in birth weight of 483 g (386-583 g) and a relative risk estimate for low birth weight of 3.81 (2,57-5.65). Conclusions. The current findings suggest that heroin use while receiving methadone may counteract the birth weight advantage gained from methadone alone. Whether this is due to fetal exposure to heroin plus methadone, to reduced antenatal care, other behavioural and environmental factors associated with concurrent use of heroin and methadone or a combination of these is unclear. Nevertheless, these results challenge the current belief that the pregnant user is always better off receiving methadone than not, and suggests that methadone may not be the appropriate treatment for the pregnant women who continue to use illicit heroin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1360-0443.1997.tb02877.x
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  • 8
    Electronic Resource
    Electronic Resource
    Assessing the relationship between maternal opiate use and antepartum haemorrhage (1998)
    Oxford, UK : Carfax Publishing Limited
    Addiction 93 (1998), S. 0 
    Details
    ISSN: 1360-0443
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Aims/Design. Assessment of the association between the regular use of opiates by women during pregnancy and antepartum haemorrhage has been made difficult by the low prevalence of these conditions observed in clinical settings. As a consequence, most published studies lack statistical power due to the small number of cases. We combined all suitable published data in a meta-analysis to assess the association more accurately. Findings. Meta-analysis produced a pooled estimate of the crude odds ratio for antepartum haemorrhage in relation to maternal opiate use of 2.33 (95%CI 1.32-4.30). Conclusions. This odds ratio estimate is consistent with a moderately strong association. Studies included did not adjust for possible confounders (e.g. prenatal care, cocaine or tobacco), so confounding is likely to account for at least some of the observed effect. The relative consistency of results from studies included in the meta-analysis that were conducted in different countries and at different times adds to the strength of the evidence for an association between opiate use and antepartum haemorrhage. Well designed studies are urgently required to assess the independent effects of different types and patterns of maternal opiate use and confounders such as cigarette smoking, illicit cocaine use and antenatal care on antepartum haemorrhage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1360-0443.1998.9310155312.x
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