1,483 research outputs found

    Cavity-enhanced optical detection of carbon nanotube Brownian motion

    Get PDF
    Optical cavities with small mode volume are well-suited to detect the vibration of sub-wavelength sized objects. Here we employ a fiber-based, high-finesse optical microcavity to detect the Brownian motion of a freely suspended carbon nanotube at room temperature under vacuum. The optical detection resolves deflections of the oscillating tube down to 50pm/Hz^1/2. A full vibrational spectrum of the carbon nanotube is obtained and confirmed by characterization of the same device in a scanning electron microscope. Our work successfully extends the principles of high-sensitivity optomechanical detection to molecular scale nanomechanical systems.Comment: 14 pages, 11 figure

    Concepts in Strategic Management and Business Policy: Achieving Sustainability -12/E.

    Get PDF
    This edition introduce a new theme that runs throughout all 12 chapter: environmental sustainability. This new theme complements the existing global issues theme carried forward from past editions. Environmental sustainability has become a strategic issues and one that will become even more important in the year ahead, as all of you struggle to deal with the consequence of climate change, global warming, and energy availability. Feature new in this edition: • Each chapter contains a boxed insert dealing with an issues in environmental sustainability. • Each chapter and with Eco Bits, interesting tidbits of ecological information, such as the number of plastic bags added to landfills each year. • Each part end with a short case dealing with topic and issues from that part’s chapter on companies ranging from Chiquita Bananas to Boeing and Airbus. • Special section on sustainability have been added to chapter 1 and 3. • A section on the natural environment has been added to the societal and task environments in chapter 4. • A section on managing strategic alliances has been added to chapter 7. • Off shoring has been added to the outsourcing section in chapter 8

    Ion-specific binding of cations to the carboxylate and of anions to the amide of alanylalanine

    Get PDF

    DATS - data containers for web applications

    Get PDF
    Data containers enable users to control access to their data while untrusted applications compute on it. However, they require replicating an application inside each container - compromising functionality, programmability, and performance. We propose DATS - a system to run web applications that retains application usability and efficiency through a mix of hardware capability enhanced containers and the introduction of two new primitives modeled after the popular model-view-controller (MVC) pattern. (1) DATS introduces a templating language to create views that compose data across data containers. (2) DATS uses authenticated storage and confinement to enable an untrusted storage service, such as memcached and deduplication, to operate on plain-text data across containers. These two primitives act as robust declassifiers that allow DATS to enforce non-interference across containers, taking large applications out of the trusted computing base (TCB). We showcase eight different web applications including Gitlab and a Slack-like chat, significantly improve the worst-case overheads due to application replication, and demonstrate usable performance for common-case usage

    Composition-Dependent Hydrogen-Bonding Motifs and Dynamics in Brønsted Acid-Base Mixtures

    No full text
    In recent years the interaction of organophosphates and imines, which is at the core of Brønsted acid organocatalysis, has been established to be based on strong ionic hydrogen bonds. Yet, besides the formation of homodimers consisting of two acid molecules and heterodimers consisting of one acid and one base, also multimeric molecular aggregates are formed in solution. These multimeric aggregates consist of one base and several acid molecules. The details of the intermolecular bonding in such aggregates, however, have remained elusive. To characterize compositiondependent bonding and bonding dynamics in these aggregates, we use linear and nonlinear infrared (IR) spectroscopy at varying molar ratios of diphenyl phosphoric acid and quinaldine. We identify the individual aggregate species, giving rise to the structured, strong, and very broad infrared absorptions, which span more than 1000 cm −1. Linear infrared spectra and density functional theory calculations of the proton transfer potential show that doubly ionic intermolecular hydrogen bonds between the acid and the base lead to absorptions which peak at ∼2040 cm −1. The contribution of singly ionic hydrogen bonds between an acid anion and an acid molecule is observed at higher frequencies. As common to such strong hydrogen bonds, ultrafast IR spectroscopy reveals rapid, ∼ 100 fs, dissipation of energy from the proton transfer coordinate. Yet, the full dissipation of the excess energy occurs on a ∼0.8−1.1 ps time scale, which becomes longer when multimers dominate. Our results thus demonstrate the coupling and collectivity of the hydrogen bonds within these complexes, which enable efficient energy transfer

    Self-localization of magnon Bose-Einstein condensates in the ground state and on excited levels: from harmonic to box-like trapping potential

    Full text link
    Long-lived coherent spin precession of 3He-B at low temperatures around 0.2 Tc is a manifestation of Bose-Einstein condensation of spin-wave excitations or magnons in a magnetic trap which is formed by the order-parameter texture and can be manipulated experimentally. When the number of magnons increases, the orbital texture reorients under the influence of the spin-orbit interaction and the profile of the trap gradually changes from harmonic to a square well, with walls almost impenetrable to magnons. This is the first experimental example of Bose condensation in a box. By selective rf pumping the trap can be populated with a ground-state condensate or one at any of the excited energy levels. In the latter case the ground state is simultaneously populated by relaxation from the exited level, forming a system of two coexisting condensates.Comment: 4 pages, 5 figure
    • …
    corecore