Using attributed variables in the implementation of concurrent and parallel logic programming systems

Incorporating the possibility of attaching attributes to variables in a logic programming system has been shown to allow the addition of general constraint solving capabilities to it. This approach is very attractive in that by adding a few primitives any logic programming system can be turned into a generic constraint logic programming system in which constraint solving can be user deñned, and at source level - an extreme example of the "glass box" approach. In this paper we propose a different and novel use for the concept of attributed variables: developing a generic parallel/concurrent (constraint) logic programming system, using the same "glass box" flavor. We argüe that a system which implements attributed variables and a few additional primitives can be easily customized at source level to implement many of the languages and execution models of parallelism and concurrency currently proposed, in both shared memory and distributed systems. We illustrate this through examples and report on an implementation of our ideas.

Chromophore-assisted light inactivation and self-organization of microtubules and motors

Chromophore-assisted light inactivation (CALI) offers the only method capable of modulating specific protein activities in localized regions and at particular times. Here, we generalize CALI so that it can be applied to a wider range of tasks. Specifically, we show that CALI can work with a genetically inserted epitope tag; we investigate the effectiveness of alternative dyes, especially fluorescein, comparing them with the standard CALI dye, malachite green; and we study the relative efficiencies of pulsed and continuous-wave illumination. We then use fluorescein-labeled hemagglutinin antibody fragments, together with relatively low-power continuous-wave illumination to examine the effectiveness of CALI targeted to kinesin. We show that CALI can destroy kinesin activity in at least two ways: it can either result in the apparent loss of motor activity, or it can cause irreversible attachment of the kinesin enzyme to its microtubule substrate. Finally, we apply this implementation of CALI to an in vitro system of motor proteins and microtubules that is capable of self-organized aster formation. In this system, CALI can effectively perturb local structure formation by blocking or reducing the degree of aster formation in chosen regions of the sample, without influencing structure formation elsewhere.

Kinetic coupling between electron and proton transfer in cytochrome c oxidase: simultaneous measurements of conductance and absorbance changes.

Bovine heart cytochrome c oxidase is an electron-current driven proton pump. To investigate the mechanism by which this pump operates it is important to study individual electron- and proton-transfer reactions in the enzyme, and key reactions in which they are kinetically and thermodynamically coupled. In this work, we have simultaneously measured absorbance changes associated with electron-transfer reactions and conductance changes associated with protonation reactions following pulsed illumination of the photolabile complex of partly reduced bovine cytochrome c oxidase and carbon monoxide. Following CO dissociation, several kinetic phases in the absorbance changes were observed with time constants ranging from approximately 3 microseconds to several milliseconds, reflecting internal electron-transfer reactions within the enzyme. The data show that the rate of one of these electron-transfer reactions, from cytochrome a3 to a on a millisecond time scale, is controlled by a proton-transfer reaction. These results are discussed in terms of a model in which cytochrome a3 interacts electrostatically with a protonatable group, L, in the vicinity of the binuclear center, in equilibrium with the bulk through a proton-conducting pathway, which determines the rate of proton transfer (and indirectly also of electron transfer). The interaction energy of cytochrome a3 with L was determined independently from the pH dependence of the extent of the millisecond-electron transfer and the number of protons released, as determined from the conductance measurements. The magnitude of the interaction energy, 70 meV (1 eV = 1.602 x 10(-19) J), is consistent with a distance of 5-10 A between cytochrome a3 and L. Based on the recently determined high-resolution x-ray structures of bovine and a bacterial cytochrome c oxidase, possible candidates for L and a physiological role for L are discussed.

Lists of books in the Harvard College Library, undated

This folder contains six leaves with undated book and shelf lists.

Daily pocket journal of John and Hannah Winthrop, 1766-1779

Small printed daily pocket journal repurposed by both John and Hannah between 1766 and 1779 to record household accounts including livestock pasturing, income received, and payments to servants, merchants, and tradesmen for food, livestock, clothing, linen, etc. Many of the pages are unused. The January-April pages contain account records from 1766-1779, one page in June has a few accounting notes from September 1779, the rest of June-November is empty, and three books are listed on a November page. The last three calendar pages contain lists of books in Hannah's handwriting dated 1773 and August 1768.

List of books received, Oct. 24, 1763 with 1764 addition

This document also lists volumes donated by a Mr. Bradstreet and Mr. Harris, as well as a list of "books saved [from the 1764 fire] by being borrowed" by individuals named Sewall, Parker, Cushing, Appleton, Brigden, Marsh, Cooke, Bowdoin, and Chardon.

List of books received, May 11, 1767(?)

The date of this list is written on the document in pencil, possibly in the hand of John Langdon Sibley. Its source and the reason for its attribution are not currently known.

List of books received, Aug. 15, 1767(?)

The date of this list is written on the document in pencil, possibly in the hand of John Langdon Sibley. Its source and the reason for its attribution are not currently known. Document indicates that books arrived "in the two Boxes marked R. O."

"An account of books belonging to the late library wch were in the hands of the senior sophisters when it was consumed by fire," ca. 1764

This list appears to be in the hand of Andrew Eliot, Librarian from 1763 to 1767. Books are listed according to format (folio, quarto, octavo) and entries indicate the surname of the student who checked the book out, its author and title, and whether or not the book had since been "returned and sent down." Some entries indicate unusual locations, including "says he returned it to the Pres[ident]" and "Dr. Marsh has it."

"Continuation of the acco[unt] of books saved from the Fire by being borrow'd," ca. 1764

Lists books borrowed by those with surnames Wyeth, Goodhue, Eliot, Langdon, Adams, Apthorp, Bowdoin, Chardon, and Mayhew. Entries include format, title, author, and volume number. Written in multiple hands.

"A list of books borrowed from the former Library & not yet return'd," ca. 1764

Lists books borrowed by many individuals, including Governor William Shirley, Colonel Brinley, General Brattle, Secretary Willard, Judge Danforth, Colonel Wendell, Thomas Oliver, Christ Bridge Marsh, and Francis Foxcroft. Entries include the author and title of the borrowed volumes.

"A Catalogue of Books Proposed for the New Hampshire donation," 1765

This catalog contains suggested purchases to be made with book purchasing funds provided by the Province of New Hampshire. Verso reads: "At a meeting of the President & Fellows of Harvard College – Voted that the above catalogue prepared by the Committee be accepted [signed] Edward Holyoke Presdt."