Aspects of Coulomb damping in rotors supported on hydrodynamic bearings

The paper is concerned with the effect of friction in drive couplings on the non-sychronous whirling of a shaft. A simplified model is used to demonstrate the effect of large coupling misalignments on the stability of the system. It is concluded that provided these misalignments are large enough, the system becomes totally stable provided the shaft is supported on bearings exhibiting a viscous damping capacity

The Hopf Rings for KO and KU

We compute the mod two homology Hopf rings of the spectra KO and KU. The spaces in these spectra are the infinite classical groups and their coset spaces, and their homology was first calculated in the Cartan seminars, but the Hopf ring structure was first determined in the second author's unpublished PhD thesis. The presentation given here serves as an introduction to the first author's much more intricate work on the connective spectrum bo. The Hopf ring viewpoint turns out to be very convenient for understanding the homological effect of various maps between classical groups and fibrations of their connective covers.Comment: 20 pages; to appear in JPA

Geometrical relations and plethysms in the Homfly skein of the annulus

The oriented framed Homfly skein C of the annulus provides the natural parameter space for the Homfly satellite invariants of a knot. It contains a submodule C+ isomorphic to the algebra of the symmetric functions. We collect and expand formulae relating elements expressed in terms of symmetric functions to Turaev's geometrical basis of C+. We reformulate the formulae of Rosso and Jones for quantum sl(N) invariants of cables in terms of plethysms of symmetric functions, and use the connection between quantum sl(N) invariants and C+ to give a formula for the satellite of a cable as an element of C+. We then analyse the case where a cable is decorated by the pattern which corresponds to a power sum in the symmetric function interpretation of C+ to get direct relations between the Homfly invariants of some diagrams decorated by power sums.Comment: 28 pages, 15 figure

The geography of rebellion: strategy and supply in the two 'Sicilian Slave Wars'

Abstract The two Sicilian ‘Slave Wars’ of the second century BC have rarely been studied in terms of their strategic complexities. Previous efforts to do so have started from the assumption that each conflict was a priori the same or similar. In addition, both wars have been placed into a separate category of analysis from other wars, leading to analyses that have characterised the wars together as disorganized guerrilla campaigns or examples of ancient marronage. In this paper I argue, by contrast, that we must consider the two conflicts as separate entities, and that we must approach their study as we would any other wars. By studying the rebel strategies of each war in terms of their relationships with the geography of Sicily and the logistics of warfare I contend that the two wars were fought in contrasting manners, with the method used in the first being highly strategic, and in the second confused and ineffectual.</jats:p

Facultative Altitudinal Movements by Mountain White-Crowned Sparrows (Zonotrichia Leucophrys Oriantha) in the Sierra Nevada

Mountain White-crowned Sparrows (Zonotrichia leucophrys oriantha) winter in Mexico and often arrive in the vicinity of their breeding grounds in the Sierra Nevada well before nesting is possible. Arrival at Tioga Pass, California (elevation 3,030 m), usually occurs in early May, but residual winter snow and adverse weather can delay nesting for weeks. We used radiotelemetry to determine whether prebreeding Mountain White-crowned Sparrows engaged in weather-related altitudinal movements during the waiting period between the end of spring migration and onset of breeding during 1995-2001, with a range of residual winter snowpacks. Interannual variation in arrival date and onset of egg laying was 18 and 41 days, respectively. We tracked females for two years and males for all seven years. During spring snowstorms (which occurred in four years), radiomarked individuals moved to lower elevation sites, where they often remained for several days. Departing birds left Tioga Pass by early afternoon and returned early in the morning after storms. More frequent storms during tracking increased the likelihood of facultative altitudinal movements, but heavier residual winter snowpack did not. Warm days increased the likelihood of birds returning to Tioga Pass from low elevation. This study demonstrates that facultative altitudinal movement behavior can be a common feature of spring arrival biology in montane-breeding birds. Received 1 November 2002, accepted 30 June 2004.Integrative Biolog

On-Line Computing With a Hierarchy of Processors

Time shared computer systems have been based upon the two techniques of multiprogramming and swapping. Multiprogramming is based on restricting each program to a portion of the total computer memory. Swapping requires considerable overhead time for loading and unloading programs. To alleviate the size restriction due to multiprogramming, segmentation is employed, resulting in fact in vastly increased swapping. A new system architecture is proposed for time shared computing that alleviates the high overhead or program size restriction. It utilizes a hierarchy of processors, where each processor is assigned tasks on the basis of four factors: interactive requirements, frequency of use, execution time, and program length. In order to study the hierarchical approach to system architecture, the Moore School Problem Solving Facility (MSPSF) was built and used. The study of the manner of operation and the reactions of the users clarified and defined the Hierarchy of Processors system architecture. The Moore School Problem Solving Facility was implemented on second generation equipment, the IBM 7040, and therefore it is not possible to adequately compare the efficiency with third generation computers operating in a swapping mode. The conclusions of this dissertation center around the methodology of designing such a system, including the specification of facilities for each level of the hierarchy. Six major conclusions are given: (1) Three processors in the hierarchy have been necessary, but it is conceivable that more may be employed in other future situations. (2) Each of the processors in the hierarchy should be general purpose. (3) Program compatibility between the processors is necessary. (4) The assigning of tasks to the processors within the system should be optionally user directed or automatic. Similarly, if a task exceeds the resources of the processor to which it has been assigned, redirection should be possible either automatically or by the user. (5) A macro language is necessary between every pair of processors for effective communication. Such a language processor, IXSYS, has been constructed and its use is described in detail in the dissertation, demonstrating the need and utility. (6) In addition to the three hierarchical processors, a separate processor may be advantageously used for storage, retrieval and management of information in files. Such a processor should be directly accessible from each of the other processors

I Resign from the YCL

Typed resignation letter addressed to the President and Members of the CCNY Young Communits League. Serves as political flyer. 2 pages. Student Publications: The Campus Newspaper Collectio

Knots and algebras

This paper gives a skein-theoretic construction of the Hecke algebras based on oriented tangles and the Homfly relations. A similar approach with unoriented tangles and Kauffman's Dubrovnik relations then gives a construction of the Birman-Wenzl algebra