On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Induced abortion

Abortion is common. Data on abortion rates are inexact but can be used to explore trends. Globally, the estimated rate in the period 2010-2014 was 35 abortions per 1000 women (aged 15-44 years), five points less than the rate of 40 for the period 1990-1994. Abortion laws vary around the world but are generally more restrictive in developing countries. Restrictive laws do not necessarily deter women from seeking abortion but often lead to unsafe practice with significant mortality and morbidity. While a legal framework for abortion is a prerequisite for availability, many laws, which are not evidence based, restrict availability and delay access. Abortion should be available in the interests of public health and any legal framework should be as permissive as possible in order to promote access. In the absence of legal access, harm reduction strategies are needed to reduce abortion-related mortality and morbidity. Abortion can be performed surgically (in the first trimester, by manual or electric vacuum aspiration) or with medication: both are safe and effective. Cervical priming facilitates surgery and reduces the risk of incomplete abortion. Diagnosis of incomplete abortion should be made on clinical grounds, not by ultrasound. Septic abortion is a common cause of maternal death almost always following unsafe abortion and thus largely preventable. While routine follow-up after abortion is unnecessary, all women should be offered a contraceptive method immediately after the abortion. This, together with improved education and other interventions, may succeed in reducing unintended pregnancy