17,330 research outputs found
Construction of irreducible polynomials through rational transformations
Let be the finite field with elements, where is a power
of a prime. We discuss recursive methods for constructing irreducible
polynomials over of high degree using rational transformations.
In particular, given a divisor of and an irreducible polynomial
of degree such that is even or , we show how to obtain from a sequence of
irreducible polynomials over with .Comment: 21 pages; comments are welcome
Organizing the innovation process : complementarities in innovation networking
This paper contributes to the developing literature on complementarities in organizational design. We test for the existence of complementarities in the use of external networking between stages of the innovation process in a sample of UK and German manufacturing plants. Our evidence suggests some differences between the UK and Germany in terms of the optimal combination of innovation activities in which to implement external networking. Broadly, there is more evidence of complementarities in the case of Germany, with the exception of the product engineering stage. By contrast, the UK exhibits generally strong evidence of substitutability in external networking in different stages, except between the identification of new products and product design and development stages. These findings suggest that previous studies indicating strong complementarity between internal and external knowledge sources have provided only part of the picture of the strategic dilemmas facing firms
Robust functional principal components: A projection-pursuit approach
In many situations, data are recorded over a period of time and may be
regarded as realizations of a stochastic process. In this paper, robust
estimators for the principal components are considered by adapting the
projection pursuit approach to the functional data setting. Our approach
combines robust projection-pursuit with different smoothing methods.
Consistency of the estimators are shown under mild assumptions. The performance
of the classical and robust procedures are compared in a simulation study under
different contamination schemes.Comment: Published in at http://dx.doi.org/10.1214/11-AOS923 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Vehicular Inter-Networking via Named Data
In this paper we apply the Named Data Networking, a newly proposed Internet
architecture, to networking vehicles on the run. Our initial design, dubbed
V-NDN, illustrates NDN's promising potential in providing a unifying
architecture that enables networking among all computing devices independent
from whether they are connected through wired infrastructure, ad hoc, or
intermittent DTN. This paper describes the prototype implementation of V-NDN
and its preliminary performance assessment
Understanding Hot-Electron Generation and Plasmon Relaxation in Metal Nanocrystals: Quantum and Classical Mechanisms
Generation of energetic (hot) electrons is an intrinsic property of any
plasmonic nanostructure under illumination. Simultaneously, a striking
advantage of metal nanocrystals over semiconductors lies in their very large
absorption cross sections. Therefore, metal nanostructures with strong and
tailored plasmonic resonances are very attractive for photocatalytic
applications. However, the central questions regarding plasmonic hot electrons
are how to quantify and extract the optically-excited energetic electrons in a
nanocrystal. We develop a theory describing the generation rates and the
energy-distributions of hot electrons in nanocrystals with various geometries.
In our theory, hot electrons are generated owing to surfaces and hot spots. The
formalism predicts that large optically-excited nanocrystals show the
excitation of mostly low-energy Drude electrons, whereas plasmons in small
nanocrystals involve mostly hot electrons. The energy distributions of
electrons in an optically-excited nanocrystal show how the quantum many-body
state in small particles evolves towards the classical state described by the
Drude model when increasing nanocrystal size. We show that the rate of surface
decay of plasmons in nanocrystals is directly related to the rate of generation
of hot electrons. Based on a detailed many-body theory involving kinetic
coefficients, we formulate a simple scheme describing the plasmon's dephasing.
In most nanocrystals, the main decay mechanism of a plasmon is the Drude
friction-like process and the secondary path comes from generation of hot
electrons due to surfaces and electromagnetic hot spots. This latter path
strongly depends on the size, shape and material of the nanocrystal,
correspondingly affecting its efficiency of hot-electron production. The
results in the paper can be used to guide the design of plasmonic nanomaterials
for photochemistry and photodetectors.Comment: 90 pages, 21 figures, including Supplementary Informatio
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