Coarse topology, enlargeability, and essentialness

Using methods from coarse topology we show that fundamental classes of closed enlargeable manifolds map non-trivially both to the rational homology of their fundamental groups and to the K-theory of the corresponding reduced C*-algebras. Our proofs do not depend on the Baum--Connes conjecture and provide independent confirmation for specific predictions derived from this conjecture.Comment: 21 pages, 2 figures. Revised version. To appear in Ann. Sci. Ecole Norm. Su

The strong Atiyah conjecture for right-angled Artin and Coxeter groups

We prove the strong Atiyah conjecture for right-angled Artin groups and right-angled Coxeter groups. More generally, we prove it for groups which are certain finite extensions or elementary amenable extensions of such groups.Comment: Minor change

The strong Novikov conjecture for low degree cohomology

We show that for each discrete group G, the rational assembly map K_*(BG) \otimes Q \to K_*(C*_{max} G) \otimes \Q is injective on classes dual to the subring generated by cohomology classes of degree at most 2 (identifying rational K-homology and homology via the Chern character). Our result implies homotopy invariance of higher signatures associated to these cohomology classes. This consequence was first established by Connes-Gromov-Moscovici and Mathai. Our approach is based on the construction of flat twisting bundles out of sequences of almost flat bundles as first described in our previous work. In contrast to the argument of Mathai, our approach is independent of (and indeed gives a new proof of) the result of Hilsum-Skandalis on the homotopy invariance of the index of the signature operator twisted with bundles of small curvature.Comment: 11 page

Firing Point: Patrol Torpedo Boats during World War II

At the beginning of American involvement in the Second World War the United States Navy developed a new class of vessel that had a tremendous impact during World War II. This vessel was the Patrol Torpedo boat. Originally designed to conduct torpedo attacks on enemy surface vessels, the PT boat successfully adapted multiple roles in addition to being a torpedo attack craft. The versatility of the Patrol Torpedo boat during World War II serving in these various roles and as an element of the US Navy has not been recognized by recent scholarship. Using primary sources from the National Archives in College Park, Maryland, and secondary sources this paper demonstrates that the Patrol Torpedo boat was a weapon that exemplified economy of force. A small inexpensive naval vessel was able to replace larger ships and work with different elements of the fleet to deny the use of coastal waters to the enemy

Toward Transaction-Specific Standards of Directorial Fiduciary Duty in the Tracking-Stock Context

In recent years, diversified corporations have increasingly turned to tracking stocks to uncouple high-growth businesses, especially Internet-related operations, from more static business entities. Tracking stock is a unique type of common stock that represents an interest in the financial performance of particular business groups within a diversified parent corporation. However, the tracked business groups are not independent of the parent corporation, and the parent\u27s board of directors still governs the affairs of each business group. This creates unique conflicts for directors who must please multiple groups of stockholders whose interests are not always consistent. Delaware courts have not announced a clear standard for dealing with directorial duties in the tracking-stock context. The three existing legal standards of corporate governance—the traditional fiduciary analysis, a contractual approach, and an entire-fairness evaluation—are individually inadequate when applied to the unique directorial conflicts arising in corporations with tracking stock. This Comment argues that Delaware courts should apply different standards of review to directorial decisions involving tracked business groups depending upon the nature of the transaction. Where the directorial decision involves primarily contractual arrangements, such as the repurchase of stock or the payment of dividends, courts should not grant tracking stockholders fiduciary protections. If the decision involves the allocation of corporate opportunity or resources, courts should apply the fiduciary principles of care and loyalty, ensuring that directors do not have a material self-interest in the transaction. Finally, if the directorial decision involves inter-group dealings, courts should require directors to demonstrate the entire fairness of the transaction regardless of whether the board was interested in the transaction

Advances in Electron-Beam-Induced-Current Analysis of Integrated Circuits

Electron-beam-induced-current (EBIC) analysis of integrated circuits and of individual semiconductor devices has become an essential technique for semiconductor device characterization as well as for failure analysis and diagnostics. This tutorial is an update of the paper presented in SEM/1981/I on the same topic and discusses advances and new trends in the applications of EBIC in recent months. Examples of EBIC measurements on high density chips, ion-implanted junctions, and shallow diffusions in thin epitaxial layers are given. Time resolved EBIC (TREBIC) is also explained and new digital readout techniques, including computer-aided data analysis, are described as they refer to detailed analyses of depletion regions associated with P-N junctions

Spray automated balancing of rotors: Methods and materials

The work described consists of two parts. In the first part, a survey is performed to assess the state of the art in rotor balancing technology as it applies to Army gas turbine engines and associated power transmission hardware. The second part evaluates thermal spray processes for balancing weight addition in an automated balancing procedure. The industry survey reveals that: (1) computerized balancing equipment is valuable to reduce errors, improve balance quality, and provide documentation; (2) slow-speed balancing is used exclusively, with no forseeable need for production high-speed balancing; (3) automated procedures are desired; and (4) thermal spray balancing is viewed with cautious optimism whereas laser balancing is viewed with concern for flight propulsion hardware. The FARE method (Fuel/Air Repetitive Explosion) was selected for experimental evaluation of bond strength and fatigue strength. Material combinations tested were tungsten carbide on stainless steel (17-4), Inconel 718 on Inconel 718, and Triballoy 800 on Inconel 718. Bond strengths were entirely adequate for use in balancing. Material combinations have been identified for use in hot and cold sections of an engine, with fatigue strengths equivalent to those for hand-ground materials

Molecular theory of hydrophobic mismatch between lipids and peptides

Effects of the mismatch between the hydrophobic length, d, of transmembrane alpha helices of integral proteins and the hydrophobic thickness, D_h, of the membranes they span are studied theoretically utilizing a microscopic model of lipids. In particular, we examine the dependence of the period of a lamellar phase on the hydrophobic length and volume fraction of a rigid, integral, peptide. We find that the period decreases when a short peptide, such that d<D_h, is inserted. More surprising, we find that the period increases when a long peptide, such that d>D_h, is inserted. The effect is due to the replacement of extensible lipid tails by rigid peptide. As the peptide length is increased, the lamellar period continues to increase, but at a slower rate, and can eventually decrease. The amount of peptide which fails to incorporate and span the membrane increases with the magnitude of the hydrophobic mismatch |d-D_h|. We explicate these behaviors which are all in accord with experiment. Predictions are made for the dependence of the tilt of a single trans-membrane alpha helix on hydrophobic mismatch and helix density.Comment: 14 pages, 5 figure