Bell Labs

About: Bell Labs is a based out in . It is known for research contribution in the topics: Laser & Optical fiber. The organization has 36499 authors who have published 59862 publications receiving 3190823 citations. The organization is also known as: Bell Laboratories & AT&T Bell Laboratories.

Seesoft-a tool for visualizing line oriented software statistics

Abstract: The Seesoft software visualization system allows one to analyze up to 50000 lines of code simultaneously by mapping each line of code into a thin row. The color of each row indicates a statistic of interest, e.g., red rows are those most recently changed, and blue are those least recently changed. Seesoft displays data derived from a variety of sources, such as version control systems that track the age, programmer, and purpose of the code (e.g., control ISDN lamps, fix bug in call forwarding); static analyses, (e.g., locations where functions are called); and dynamic analyses (e.g., profiling). By means of direct manipulation and high interaction graphics, the user can manipulate this reduced representation of the code in order to find interesting patterns. Further insight is obtained by using additional windows to display the actual code. Potential applications for Seesoft include discovery, project management, code tuning, and analysis of development methodologies. >

Offset masks for lift‐off photoprocessing

Abstract: We describe a technique using photolithography to produce submicron‐scale thin‐film structures and simple multilevel structures by single‐mask lift‐off processing. The technique employs masks offset from the substrate and oblique angle thin‐film deposition. It provides a simple means of making small‐area Josephson junctions and varying‐thickness superconducting bridges and is suitable for the inclusion of these devices in circuits. The examples we show emphasize such applications in superconductivity; however, the technique may find uses in other fields as well.

A data structure for dynamic trees

Abstract: We propose a data structure to maintain a collection of vertex-disjoint trees under a sequence of two kinds of operations: a link operation that combines two trees into one by adding an edge, and a cut operation that divides one tree into two by deleting an edge. Our data structure requires O(log n) time per operation when the time is amortized over a sequence of operations. Using our data structure, we obtain new fast algorithms for the following problems: (1) Computing deepest common ancestors. (2) Solving various network flow problems including finding maximum flows, blocking flows, and acyclic flows. (3) Computing certain kinds of constrained minimum spanning trees. (4) Implementing the network simplex algorithm for the transshipment problem. Our most significant application is (2); we obtain an O(mn log n)-time algorithm to find a maximum flow in a network of n vertices and m edges, beating by a factor of log n the fastest algorithm previously known for sparse graphs.

Calculation of the superconducting state parameters with retarded electron- phonon interaction

Abstract: The energy gap and other parameters of the superconducting state are calculated from the Bardeen-Cooper-Schrieffer theory in Gor'kov-Eliashberg form, using a realistic retarded electron-electron interaction via phonons and including the Coulomb repulsion. The solution is facilitated by observing that only the local phonon interaction, mediated entirely by short-wavelength phonons, is important, and that a good approximation for the phonon spectrum is therefore an Einstein model rather than Debye model. The resulting equation is solved by an approximate iteration procedure. The results are similar to earlier gap equations but the derivation gives a precise meaning to the interaction and cutoff parameters of earlier theories. The numerical results are in good order-of-magnitude agreement with the observed transition temperatures but lead to an isotope effect at least 15% less than the accepted -\textonehalf{} exponent (${T}_{c}$ proportional to ${M}^{\ensuremath{-}\frac{1}{2}}$). Also, the present theory predicts that all metals should be superconductors, although those not observed to do so would have remarkably low transition temperatures.

Ordering and Antiferromagnetism in Ferrites

Abstract: The octahedral sites in the spinel structure form one of the anomalous lattices in which it is possible to achieve essentially perfect short-range order while maintaining a finite entropy. In such a lattice nearest-neighbor forces alone can never lead to long-range order, while calculations indicate that even the longrange Coulomb forces are only 5% effective in creating long-range order. This is shown to have many possible consequences both for antiferromagnetism in "normal" ferrites and for ordering in "inverse" ferrites.