Continuous Magnetophoretic Separation of Blood Cells from Plasma at the Microscale

We present a method for the direct and continuous separation of red and white blood cells from plasma at the microscale. The method is implemented in a microfluidic system with magnetic functionality. The fluidic structure within the microsystem consists of an inlet and a single microfluidic channel with multiple outlets. The magnetic functionality is provided by an array of integrated soft-magnetic elements that are embedded transverse and adjacent to the microchannel. The elements are magnetized using an external field, and once magnetized they produce a magnetic force on blood cells as they flow through the microchannel. In whole blood, white blood cells (WBCs) behave as diamagnetic microparticles, while red blood cells (RBCs) exhibit diamagnetic or paramagnetic behavior depending on the oxygenation of their hemoglobin. We study the motion of blood cells through the microchannel using a mathematical model that takes into account the magnetic, fluidic and gravitational forces on the cells. We use the model to study blood cell separation, and our analysis indicates that the microsystem is capable of separating WBC-rich plasma, deoxygenated RBC-rich plasma and cell-depleted plasma into respective outlets.Comment: Submitted to Journal of Applied Physic

(G)hosting television: Ghostwatch and its medium

This article’s subject is Ghostwatch (BBC, 1992), a drama broadcast on Halloween night of 1992 which adopted the rhetoric of live non-fiction programming, and attracted controversy and ultimately censure from the Broadcasting Standards Council. In what follows, we argue that Ghostwatch must be understood as a televisually-specific artwork and artefact. We discuss the programme’s ludic relationship with some key features of television during what Ellis (2000) has termed its era of ‘availability’, principally liveness, mass simultaneous viewing, and the flow of the television super-text. We trace the programme’s television-specific historicity whilst acknowledging its allusions and debts to other media (most notably film and radio). We explore the sophisticated ways in which Ghostwatch’s visual grammar and vocabulary and deployment of ‘broadcast talk’ (Scannell 1991) variously ape, comment upon and subvert the rhetoric of factual programming, and the ends to which these strategies are put. We hope that these arguments collectively demonstrate the aesthetic and historical significance of Ghostwatch and identify its relationship to its medium and that medium’s history. We offer the programme as an historically-reflexive artefact, and as an exemplary instance of the work of art in television’s age of broadcasting, liveness and co-presence

An amphitropic cAMP-binding protein in yeast mitochondria

ABSTRACT: We describe the first example of a mitochondrial protein with a covalently attached phos-phatidylinositol moiety acting as a membrane anchor. The protein can be metabolically labeled with both stearic acid and inositol. The stearic acid label is removed by phospholipase D whereupon the protein with the retained inositol label is released from the membrane. This protein is a cAMP receptor of the yeast Saccharomyces cereuisiae and tightly associated with the inner mitochondrial membrane. However, it is converted into a soluble form during incubation of isolated mitochondria with Ca2+ and phospholipid (or lipid derivatives). This transition requires the action of a proteinaceous, N-ethylmaleimide-sensitive component of the intermembrane space and is accompanied by a decrease in the lipophilicity of the cAMP receptor. We propose that the component of the intermembrane space triggers the amphitropic behavior of the mitochondrial lipid-modified CAMP-binding protein through a phospholipase activity. Only in recent years specific fatty acids have been recog-nized to play important roles in the association of proteins with membranes. Both noncovalent and covalent interactions be-tween fatty acids and proteins have been reported. Among the latter are GTP-binding proteins (Molenaar et al., 1988)