No abstract

Placenta accreta is an uncommon entity in which the placental villi invade the myometrium. The classic sonographic findings include the absence of a hypoechoic retroplacental zone, the presence of dilated vessels extending from the placenta through the myometrium, irregular cystic spaces in the placenta, and pulsatile maternal blood flow within these hypoechoic spaces. It is often accompanied by placenta previa. In this study, the authors report findings in six cases, four of which were accurately diagnosed sonographically as placenta accreta, one which resulted in a false-positive diagnosis, and one which resulted in a false-negative diagnosis. We review the roles of two-dimensional imaging, color-flow Doppler, and power Doppler in assessing this condition. Because of the associated high risk of maternal exsanguination, ultrasonography is an important and reliable tool in diagnosing accreta.

In the case of the proportional allocation of goods and burdens, the shares of all agents with respect to their values are equal, i.e., they form a constant sequence. In a degressively proportional allocation this sequence is nondecreasing when agents are increasingly ordered according to their values. The division performed according to this principle is ambiguous, and its selection requires many negotiations among participants. The aim of this paper is to limit the range of such negotiations when the problem is complex, i.e., the set of feasible solutions has high cardinality. It can be done thanks to a numerical analysis of the set of all feasible solutions, and eliminating allocations favoring or disfavoring some coalitions of agents. The problem is illustrated by the case study of allocating seats in the European Parliament in its 2019–2024 term.