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8 - Puerperal sepsis in low- and middle-income settings: past, present and future
- from SECTION 2 - CLINICAL PROBLEMS AND SOLUTIONS – MATERNAL
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- By Julia Hussein, University of Aberdeen, Leighton Walker, University of Aberdeen
- Edited by Sean Kehoe, James Neilson, University of Liverpool, Jane Norman, University of Edinburgh
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- Book:
- Maternal and Infant Deaths
- Published online:
- 05 February 2014
- Print publication:
- 01 June 2010, pp 131-148
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- Chapter
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Summary
Introduction
Puerperal sepsis is an infective condition in the mother following childbirth and one of the leading causes of maternal mortality worldwide. It is the third most common cause of maternal death as a result of childbirth, after haemorrhage and abortion, accounting for as much as 15% of the 500000 maternal lives lost annually. In low-and middle-income countries, infections occurring in the puerperium are reportedly the sixth leading cause of disease burden for women in their reproductive years. Complications in the mother such as secondary postpartum haemorrhage and infertility can result, and there is an association with early-onset neonatal sepsis.
Reducing puerperal sepsis in women will contribute to achieving Millennium Development Goals (MDGs) 4 and 5 on child survival and maternal health. Despite the importance of puerperal sepsis globally, there is surprisingly little current interest in the condition. Even in industralised countries such as the UK, although deaths from puerperal sepsis are now rare, the latest Confidential Enquiry into Maternal Deaths suggests that the incidence of complications is increasing and failure of clinicians to recognise signs and symptoms of puerperal sepsis have contributed to maternal mortality.
In developing countries, puerperal sepsis continues to cause many unnecessary deaths, mainly because of inadequate access to care during childbirth and poor quality of care. Women may not be able to reach health professionals during labour and delivery care provided in the home setting with attendants who lack the necessary skills can increase the risk of infection.
Shear-free turbulence near a flat free surface
- D. T. Walker, R. I. Leighton, L. O. Garza-Rios
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- Journal:
- Journal of Fluid Mechanics / Volume 320 / 10 August 1996
- Published online by Cambridge University Press:
- 26 April 2006, pp. 19-51
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- Article
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In this study the evolution of initially homogeneous and isotropic turbulence in the presence of a free surface was investigated. The Navier–Stokes equations were solved via direct pseudo-spectral simulation with a resolution of 963. The Reynolds number based on the volume-averaged turbulence kinetic energy and dissipation rate was 147. Periodic boundary conditions were used in two dimensions, and the top and bottom sides of the domain were flat and shear-free. A random, divergence-free velocity field with a prescribed spectrum was used as the initial condition. An ensemble of sixteen separate simulations was used to calculate statistics.
Near the surface, the Reynolds stresses are anisotropic and the anisotropy extends a distance from the surface roughly equal to the turbulent lengthscale. The tangential vorticity fluctuations also vanish near the surface, owing to the no-shear condition, causing a corresponding decrease in the fluctuating enstrophy. The thickness of the region in which the surface affects the vorticity distribution is roughly one-tenth the turbulent lengthscale. The stress anisotropy near the surface appears to be maintained by reduced dissipation for the tangential velocity fluctuations, reduced pressure–strain transfer from the tangential to surface-normal velocity fluctuations, and rapid decay of the surface-normal velocity fluctuations due to dissipation. The turbulence kinetic energy rises in the near-surface region owing to a decrease in dissipation at the surface. This decrease in dissipation results from the local reduction in enstrophy owing to the vanishing of the tangential vorticity fluctuations at the surface. At the free surface, the mean pressure rises. This is also due to the reduction in enstrophy.
While the tangential vorticity must vanish at the free surface, the flow is fully three-dimensional up to the surface and the production of surface-normal vorticity by vortex stretching attains a maximum at the free surface. The contribution to the total enstrophy by the surface-normal vorticity fluctuations remains relatively constant over depth. The production of the surface-normal enstrophy component due to vortex stretching is roughly balanced by turbulent transport of enstrophy away from the surface. Near the surface, there are elevated levels of production of tangential vorticity by both vortex-stretching and fluctuating shear strains.