Search

The observation that hydroxyapatite (HA) formation from metastable solutions can be induced by nucleating proteins such as bone sialoprotein (BSP) suggests a possible treatment for bone defects. The introduction of a mixture of nucleating protein and type I collagen should result in a defect becoming filled with a mineralized collagenous matrix that is biologically and mechanically compatible and capable of being remodeled. To create a nucleating protein that would interact with collagen fibrils, we combined the putative collagen-binding site of mouse decorin with one of two putative HA-nucleating sites of pig BSP. The resulting chimeric protein induced the formation of HA crystals in a steady-state agarose gel system and bound with high affinity to fibrillar type I collagen. The addition of chimeric protein to collagen gels perfused with low concentrations of calcium and phosphate resulted in the deposition of large, apparently needle-shaped HA crystals on the surface of collagen fibrils. These findings suggest that the BSP-decorin chimeric protein could be capable of inducing the mineralization of collagen in vivo.

We describe a design of fault-tolerant features for the PANSAT communications satellite, a design which can address a wide variety of possible faults. We discuss system errors, program errors, and data errors, each subdivided into a variety of types. We discuss acceptance tests that can be used to detect faults, and the appropriate remediation methods for each type.

In this essay I wish to consider the strange symmetry that connects the two most successful periods of popular drama in the English-speaking world, the London public drama of the sixteenth and seventeenth centuries and the Hollywood filmed drama of the twentieth century1 — a symmetry that, found under such clearly differentiated circumstances, may tempt us to believe that popular drama is a specific genre. But my aim is not to pursue such possibility; I seek only to present evidence and leave conclusions to look after themselves. I discuss the evidence under two headings: first I shall deal with the organisational structure of the drama in both periods and then I discuss what is derivative from this, the dramaturgy of plays produced inside the organisation.

Study of the calcification of cartilage in endochondral ossification has yielded two apparently contradictory views of the role of proteoglycan in this process. The ability of proteoglycan to act as a calcium-concentrating agent (Kalksalzfänger) in cartilage is consistent with the view that proteoglycans are promoters of calcification. However, study of their effect on hydroxyapatite formation in vitro suggests that proteoglycans are inhibitors of cartilage calcification. A resolution of this paradox is now proposed. Proteoglycans inhibit hydroxyapatite formation under in vitro conditions of limited calcium availability (in part) by binding calcium ions. However, under in vivo conditions of essentially infinite calcium availability, proteoglycans may promote hydroxyapatite formation, since binding of calcium to proteoglycan will not decrease the free calcium concentration, and the bound calcium may easily be displaced. Therefore, it is proposed that the role of proteoglycans in the calcification of cartilage is to function as a cation-exchanging calcium reservoir.

Since the First Folio says that Shakespeare wrote history plays I think there is a great deal to be said for assuming not only that he did so but did so in the plays thus designated and no others; let evidence precede definition. It is true of course that the evidence available is mixed; Elizabethan generic vocabulary is notoriously spongy: contemporary title pages give us such hybrids as The Tragedy of Richard II, The Tragedy of Richard III, The History of Troilus and Cressida, The True Chronicle History of King Lear, A Pleasant Conceited History called The Taming of a Shrew. The Folio's generic divisions seem to belong, however, to a different mode of discourse: F1 is a company volume, and I have no doubt that its division of plays into Comedies, Histories, and Tragedies reflects company understanding of the repertory, and so, I take it, the understanding of that good company man, William Shakespeare. Academic critics inevitably prefer definitions to be less blandly empirical, for what space for dazzling reinventions, for pulling rabbits out of hats, not to mention a name in lights, is left available by so preconditioning an acceptance? As professional systematizers we like to be seen to generate our definitions from general principles and our first chapters from titles such as 'What is a history play? Some problems and answers'.

The original and substantive texts of Marlowe's Doctor Faustus (the Quartos of 1604 and 1616) present the play completely without the punctuation of act division or scene enumeration. This is common enough in the play-texts of the period. Indeed it is much the commonest form in plays written for the public theatres. Shakespeare's Henry V and Pericles are without divisions in their quarto texts, but we know that they were written with a five-act structure in mind—the choruses tell us that.What is exceptional in the textual history of Doctor Faustus is not the lack of division in the original texts; it is rather the reluctance of modern editors to impose an act-structure on the modern texts. This is curious, but it seems possible to discern why the reluctance exists and a survey of the modern editions of Faustus throws some interesting light on critical attitudes to the subject matter of the play.