11,523 research outputs found
The One-Loop H^2R^3 and H^2(DH)^2R Terms in the Effective Action
We consider the one-loop B^2h^3 and B^4h amplitudes in type II string theory,
where B is the NS-NS two-form and h the graviton, and expand to lowest order in
alpha'. After subtracting diagrams due to quartic terms in the effective
action, we determine the presence and structure of both an H^2R^3 and
H^2(DH)^2R term. We show that both terms are multiplied by the usual
(t_8t_8\pm{1/8}\epsilon_{10}\epsilon_{10}) factor.Comment: 20 pages, 3 figures; corrected typo
The Public Defender Defendant: A Model Statutory Approach to Public Defender Malpractice Liability
Target shape dependence in a simple model of receptor-mediated endocytosis and phagocytosis
Phagocytosis and receptor-mediated endocytosis are vitally important particle
uptake mechanisms in many cell types, ranging from single-cell organisms to
immune cells. In both processes, engulfment by the cell depends critically on
both particle shape and orientation. However, most previous theoretical work
has focused only on spherical particles and hence disregards the wide-ranging
particle shapes occurring in nature, such as those of bacteria. Here, by
implementing a simple model in one and two dimensions, we compare and contrast
receptor-mediated endocytosis and phagocytosis for a range of biologically
relevant shapes, including spheres, ellipsoids, capped cylinders, and
hourglasses. We find a whole range of different engulfment behaviors with some
ellipsoids engulfing faster than spheres, and that phagocytosis is able to
engulf a greater range of target shapes than other types of endocytosis.
Further, the 2D model can explain why some nonspherical particles engulf
fastest (not at all) when presented to the membrane tip-first (lying flat). Our
work reveals how some bacteria may avoid being internalized simply because of
their shape, and suggests shapes for optimal drug delivery.Comment: 18 pages, 5 figure
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