5,768 research outputs found

    A calculus for ideal triangulations of three-manifolds with embedded arcs

    Full text link
    Refining the notion of an ideal triangulation of a compact three-manifold, we provide in this paper a combinatorial presentation of the set of pairs (M,a), where M is a three-manifold and a is a collection of properly embedded arcs. We also show that certain well-understood combinatorial moves are sufficient to relate to each other any two refined triangulations representing the same (M,a). Our proof does not assume the Matveev-Pergallini calculus for ideal triangulations, and actually easily implies this calculus.Comment: 32 pages, 30 figure

    Nonequilibrium dephasing in Coulomb blockade quantum dots

    Full text link
    We present a theory of zero-bias anomalies and dephasing rates for a Coulomb-blockaded quantum dot, driven out of equilibrium by coupling to voltage biased source and drain leads. We interpret our results in terms of the statistics of voltage fluctuations in the system.Comment: 4 page

    Extending Hardware Transactional Memory Capacity via Rollback-Only Transactions and Suspend/Resume

    Get PDF
    Transactional memory (TM) aims at simplifying concurrent programming via the familiar abstraction of atomic transactions. Recently, Intel and IBM have integrated hardware based TM (HTM) implementations in commodity processors, paving the way for the mainstream adoption of the TM paradigm. Yet, existing HTM implementations suffer from a crucial limitation, which hampers the adoption of HTM as a general technique for regulating concurrent access to shared memory: the inability to execute transactions whose working sets exceed the capacity of CPU caches. In this paper we propose P8TM, a novel approach that mitigates this limitation on IBM\u27s POWER8 architecture by leveraging a key combination of techniques: uninstrumented read-only transactions, Rollback Only Transaction-based update transactions, HTM-friendly (software-based) read-set tracking, and self-tuning. P8TM can dynamically switch between different execution modes to best adapt to the nature of the transactions and the experienced abort patterns. In-depth evaluation with several benchmarks indicates that P8TM can achieve striking performance gains in workloads that stress the capacity limitations of HTM, while achieving performance on par with HTM even in unfavourable workloads

    Transfer of Business Management Technologies in Civil Service Personnel Management

    Get PDF
    The article deals with the management of technology transfer process used in the private sector in human resource management of the state civil service. The basic way of formation of personnel technologies in government and the characteristic of each of them. The author describes the mechanism for testing and introduction of modern technologies of personnel in public authorities. The necessity of introduction of the activity of public authorities personnel technologies successfully used in the private sector, also describes the factors limiting their use in the management of civil service personnel

    ThreadScan: Automatic and Scalable Memory Reclamation

    Get PDF
    The concurrent memory reclamation problem is that of devising a way for a deallocating thread to verify that no other concurrent threads hold references to a memory block being deallocated. To date, in the absence of automatic garbage collection, there is no satisfactory solution to this problem. Existing tracking methods like hazard pointers, reference counters, or epoch-based techniques like RCU, are either prohibitively expensive or require significant programming expertise, to the extent that implementing them efficiently can be worthy of a publication. None of the existing techniques are automatic or even semi-automated. In this paper, we take a new approach to concurrent memory reclamation: instead of manually tracking access to memory locations as done in techniques like hazard pointers, or restricting shared accesses to specific epoch boundaries as in RCU, our algorithm, called ThreadScan, leverages operating system signaling to automatically detect which memory locations are being accessed by concurrent threads. Initial empirical evidence shows that ThreadScan scales surprisingly well and requires negligible programming effort beyond the standard use of Malloc and Free

    Comprehending Complexity: Data-Rate Constraints in Large-Scale Networks

    Get PDF
    This paper is concerned with the rate at which a discrete-time, deterministic, and possibly large network of nonlinear systems generates information, and so with the minimum rate of data transfer under which the addressee can maintain the level of awareness about the current state of the network. While being aimed at development of tractable techniques for estimation of this rate, this paper advocates benefits from directly treating the dynamical system as a set of interacting subsystems. To this end, a novel estimation method is elaborated that is alike in flavor to the small gain theorem on input-to-output stability. The utility of this approach is demonstrated by rigorously justifying an experimentally discovered phenomenon. The topological entropy of nonlinear time-delay systems stays bounded as the delay grows without limits. This is extended on the studied observability rates and appended by constructive upper bounds independent of the delay. It is shown that these bounds are asymptotically tight for a time-delay analog of the bouncing ball dynamics

    Structure, properties and phase composition of composite materials based on the system NiTi-TiB2

    Get PDF
    This article considers issues pertinent to the research of the phase composition, structure and mechanical properties of materials obtained from powders of composite (Ni-Ti)-TiB2, which have prospective applications in aerospace and automotive industry and engine construction. The starting powder materials (Ni-Ti)-TiB2 were obtained by self-propagating high-temperature synthesis (SHS). Research samples were produced using high-temperature vacuum sintering. It was shown that the use of such materials increases the wettability of the particles and allows the production of composites, the density of which is 95% of the theoretical one. Average particle size was 1.54 µm, average microhardness was 8 GPa, which is an order of magnitude higher than the average microhardness of pure nickel-based and titanium-based alloys, and the ultimate strength values were comparable to those of tungsten-based heavy alloys
    corecore