Biological membranes have been under intensive investigation for several decades. Despite very great experimental challenges, membranes are at last beginning to reveal their secrets. In this book, leading investigators of membrane structure and function report on progress in three related fields: specialization of membrane regions, asymmetry in transport properties, and differentiation of cell faces in epithelia.

"Specialization at the Molecular Level" is the subject of the first section; in it, the authors consider such problems as the biogenesis of membranes, the geometry of protein-lipid relationships, and the physical properties of membrane receptor-sites. In the second section, "Asymmetry in Transport," such topics as the sodium-potassium pump, proton translocation, and anion transport are covered. The last section is entitled "Polar Faces in Epithelia" and deals with the complex properties of ion transport across the complex membrane environment maintained by surfaces such as the renal tubular epithelia.

Most observers agree that modern physical theory attempts to provide objective representations of reality. However, the claim that these representations are based on conventional choices is viewed by many as a denial of their objectivity. As a result, objectivity and conventionality in representation are often framed as polar opposites.

Offering a new appraisal of symmetry in modern physics, employing detailed case studies from relativity theory and quantum mechanics, Objectivity, Invariance, and Convention contends that the physical sciences, though dependent on convention, may produce objective representations of reality. Talal Debs and Michael Redhead show that both realists and constructivists have recognized important elements of an understanding of science that may not be contradictory.

The position—“perspectival invariantism”—introduced in this book highlights the shortcomings of existing approaches to symmetry in physics, and, for the constructivist, demonstrates that a dependence on conventions in representation reaches into the domain of the most technical sciences. For the realist, it stands as evidence against the claim that conventionality must undermine objectivity. We can be committed to the existence of a single real ontology while maintaining a cultural view of science.

Few Elizabethans left the image of their personalities cut so deeply into the Renaissance imagination as did Sir Philip Sidney. Widely admired in his own time, Sidney must seem to the modern reader almost universally accomplished. His talents as courtier, diplomat, soldier, scholar, novelist, and poet are history.

Almost immediately after Sidney's death in battle against the Spaniards in the Low Countries, the process of legend began, and the legend has survived, sometimes obscuring the facts. The versatile "Renaissance man" has become, in the eyes of some critics, the romantic lover whose frustrations and despair found release in the "confessional" form of the sonnet sequence, Astrophel and Stella, and in other poems. To show these poems to be consciously constructed works of art, not simply passionate outbursts of romantic emotion, is one aim of this study.

The author examines Sidney as poet and critic, concentrating his study on rhetorical technique and poetic rhythm and form. He shows Sidney experimenting with the symmetrical possibilities of rhythm and phrase; practicing the ornateness current and acceptable in his day. He examines Sidney's comment on such a style in The Defense of Poesy and the ways in which the poet's own work agreed with or departed from his expressed opinions. He also balances Sidney's poetry against the powerful tradition of Petrarchan love literature and the equally powerful Renaissance impulse to subject passion to the rule of reason. Finally, in an extended analysis of Astrophel and Stella, he shows Sidney as the master of a plainer, wittier, more subtly fashioned style and a complex, more dramatically immediate form. What emerges from the study is not the personality of the poet, but the principles of his art and the value of his achievement in the mainstream of English Renaissance verse.