96,385 research outputs found
Electron-Phonon interaction and electronic decoherence in molecular conductors
We perform a brief but critical review of the Landauer picture of transport
that clarifies how decoherence appears in this approach. On this basis, we
present different models that allow the study of the coherent and decoherent
effects of the interaction with the environment in the electronic transport.
These models are particularly well suited for the analysis of transport in
molecular wires. The effects of decoherence are described through the
D'Amato-Pastawski model that is explained in detail. We also consider the
formation of polarons in some models for the electron-vibrational interaction.
Our quantum coherent framework allows us to study many-body interference
effects. Particular emphasis is given to the occurrence of anti-resonances as a
result of these interferences. By studying the phase fluctuations in these
soluble models we are able to identify inelastic and decoherence effects. A
brief description of a general formulation for the consideration of
time-dependent transport is also presented.Comment: 32 pages, 11 eps figures. To appear in Chemical Physics (Special
Molecular Electronics Number
Information requirements for enterprise systems
In this paper, we discuss an approach to system requirements engineering, which is based on using models of the responsibilities assigned to agents in a multi-agency system of systems. The responsibility models serve as a basis for identifying the stakeholders that should be considered in establishing the requirements and provide a basis for a structured approach, described here, for information requirements elicitation. We illustrate this approach using a case study drawn from civil emergency management
Controlling Light Through Optical Disordered Media : Transmission Matrix Approach
We experimentally measure the monochromatic transmission matrix (TM) of an
optical multiple scattering medium using a spatial light modulator together
with a phase-shifting interferometry measurement method. The TM contains all
information needed to shape the scattered output field at will or to detect an
image through the medium. We confront theory and experiment for these
applications and we study the effect of noise on the reconstruction method. We
also extracted from the TM informations about the statistical properties of the
medium and the light transport whitin it. In particular, we are able to isolate
the contributions of the Memory Effect (ME) and measure its attenuation length
Authentication and authorisation in entrusted unions
This paper reports on the status of a project whose aim is to implement and demonstrate in a real-life environment an integrated eAuthentication and eAuthorisation framework to enable trusted collaborations and delivery of services across different organisational/governmental jurisdictions. This aim will be achieved by designing a framework with assurance of claims, trust indicators, policy enforcement mechanisms and processing under encryption to address the security and confidentiality requirements of large distributed infrastructures. The framework supports collaborative secure distributed storage, secure data processing and management in both the cloud and offline scenarios and is intended to be deployed and tested in two pilot studies in two different domains, viz, Bio-security incident management and Ambient Assisted Living (eHealth). Interim results in terms of security requirements, privacy preserving authentication, and authorisation are reported
Multimode laser cooling and ultra-high sensitivity force sensing with nanowires
Photo-induced forces can be used to manipulate and cool the mechanical motion
of oscillators. When the oscillator is used as a force sensor, such as in
atomic force microscopy, active feedback is an enticing route to enhancing
measurement performance. Here, we show broadband multimode cooling of dB
down to a temperature of ~K in the stationary regime. Through the use
of periodic quiescence feedback cooling, we show improved signal-to-noise
ratios for the measurement of transient signals. We compare the performance of
real feedback to numerical post-processing of data and show that both methods
produce similar improvements to the signal-to-noise ratio of force
measurements. We achieved a room temperature force measurement sensitivity of
N with integration time of less than ms. The high
precision and fast force microscopy results presented will potentially benefit
applications in biosensing, molecular metrology, subsurface imaging and
accelerometry.Comment: 16 pages and 3 figures for the main text, 14 pages and 5 figures for
the supplementary informatio
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