460 research outputs found

    Living lab methodology as an assessment tool for mass customization

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    Mass customization has been regularly used as a growth strategy during the last decades. The strength of this approach stems from offering products adjusted to customers' individual needs, resulting in added value. The latter resides in the word 'custom,' implying unique and utilitarian products allowing for self-expression of the consumer. Researchers and practitioners however predominantly focused on the company's internal processes to optimize mass customization, often resulting in market failure. As a response, a framework with five factors determining the success of mass customization was developed. Additionally, Living Lab methodologies have been used to improve innovation contexts that were too closed. This paper will fill a gap in the literature by demonstrating that the integration of the five-factor framework in the Living Lab methodology is well suited to determine the possible success or failure of a mass-customized product in the market by means of a single case study

    Terahertz Magneto Optical Polarization Modulation Spectroscopy

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    We report the development of new terahertz techniques for rapidly measuring the complex Faraday angle in systems with broken time-reversal symmetry using the cyclotron resonance of a GaAs two-dimensional electron gas in a magnetic field as a system for demonstration of performance. We have made polarization modulation, high sensitivity (< 1 mrad) narrow band rotation measurements with a CW optically pumped molecular gas laser, and by combining the distinct advantages of terahertz (THz) time domain spectroscopy and polarization modulation techniques, we have demonstrated rapid broadband rotation measurements to < 5 mrad precision.Comment: 25 pages including 7 figures, introduces use of rotating polarizer with THz TDS for Complex Faraday Angle determinatio

    The Neuromodulator Adenosine Regulates Oligodendrocyte Migration at Motor Exit Point Transition Zones

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    During development, oligodendrocyte progenitor cells (OPCs) migrate extensively throughout the spinal cord. However, their migration is restricted at transition zones (TZs). At these specialized locations, unique glial cells in both zebrafish and mice play a role in preventing peripheral OPC migration, but the mechanisms of this regulation are not understood. To elucidate the mechanisms that mediate OPC segregation at motor exit point (MEP) TZs, we performed an unbiased small-molecule screen. Using chemical screening and in vivo imaging, we discovered that inhibition of A2a adenosine receptors (ARs) causes ectopic OPC migration out of the spinal cord. We provide in vivo evidence that neuromodulation, partially mediated by adenosine, influences OPC migration specifically at the MEP TZ. This work opens exciting possibilities for understanding how OPCs reach their final destinations during development and identifies mechanisms that could promote their migration in disease

    Ioffe Time in Double Logarithmic Approximation

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    We analyze the light cone (Ioffe) time structure of the gluon distribution function in the double logarithmic approximation. We show that due to QCD evolution Ioffe equation is modified. The characteristic light cone time of the gluons does not increase as fast with increasing energy (decreasing Bjorken x) as predicted by the parton distributions exhibiting Bjorken scaling due to the increase of the transverse momenta of the gluons in the DGLAP ladder.Comment: 13 pages, 1 figur

    Low energy onset of nuclear shadowing in photoabsorption

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    The early onset of nuclear shadowing in photoabsorption at low photon energies has recently been interpreted as a possible signature of a decrease of the rho meson mass in nuclei. We show that one can understand this early onset within simple Glauber theory if one takes the negative real part of the rho N scattering amplitudes into account, corresponding to a higher effective mass of the rho meson in nuclear medium.Comment: REVTEX, 9 pages, including 4 eps figure

    Inclusive Heavy-Flavor Production from Nuclei

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    We describe a light-cone wave function formulation for hadroproduction of heavy-flavors at high energies. At moderate values of xFx_F heavy-flavor production can be viewed as a diffractive excitation of heavy quark-antiquark Fock states, present in the interacting gluon from the projectile. The approach developed here is well suited to address coherence effects in heavy-quark production from nuclei at small values of x_{t} \lsim 0.1\cdot A^{-1/3}.Comment: 14 pages with 3 figures. To appear in Z. Phys.

    Shadowing, Binding and Off-Shell Effects in Nuclear Deep Inelastic Scattering

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    We present a unified description of nuclear deep inelastic scattering (DIS) over the whole region 0<x<10<x<1 of the Bjorken variable. Our approach is based on a relativistically covariant formalism which uses analytical properties of quark correlators. In the laboratory frame it naturally incorporates two mechanisms of DIS: (I) scattering from quarks and antiquarks in the target and (II) production of quark-antiquark pairs followed by interactions with the target. We first calculate structure functions of the free nucleon and develop a model for the quark spectral functions. We show that mechanism (II) is responsible for the sea quark content of the nucleon while mechanism (I) governs the valence part of the nucleon structure functions. We find that the coherent interaction of qˉq\bar qq pairs with nucleons in the nucleus leads to shadowing at small xx and discuss this effect in detail. In the large xx region DIS takes place mainly on a single nucleon. There we focus on the derivation of the convolution model. We point out that the off-shell properties of the bound nucleon structure function give rise to sizable nuclear effects.Comment: 29 pages (and 10 figures available as hard copies from Authors), REVTE

    Pions in isospin asymmetric nuclei

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    Using a pair of the lightest mirror nuclei, 3^3He and 3^3H, we study the effect of the medium modification of pion fields on the flavor non-singlet structure function. The change of the pion fields leads to an enhancement of the flavor asymmetry of the antiquark distributions in a nucleus.Comment: 14 pages (4 figures

    Comments on Exclusive Electroproduction of Transversely Polarized Vector Mesons

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    We discuss the electroproduction of light vector mesons from transversely polarized photons. Here QCD factorization cannot be applied as shown explicitly in a leading order calculation of corresponding Feynman diagrams. It is emphasized that present infrared singular contributions cannot be regularized through phenomenological meson distribution amplitudes with suppressed endpoint configurations. We point out that infrared divergencies arise also from integrals over skewed parton distributions of the nucleons. In a phenomenological analysis of transverse vector meson production model dependent regularizations have to be applied. If this procedure preserves the analytic structure suggested by a leading order calculation of Feynman diagrams, one obtains contributions from nucleon parton distributions and their derivatives. In particular polarized gluons enter only through their derivative
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