Dark-field optical coherence microscopy

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Ongoing research on the human body provides insights that are important for understanding its mechanisms and the impact of new drugs. To study these complex processes in vivo, animal models, such as rodents, are used because they provide a living system that can be observed over an entire life cycle. However, from an ethical standpoint, this practice is increasingly difficult to justify. Following the 3R initiative, future research tries to reduce animal testing. Cell cultures offer an in vitro alternative

Maps of biological tissues at subcellular detail are key for understanding how organs function. X-ray nanotomography is a promising alternative to volume electron microscopy: it has the potential to nondestructively image millimeter-sized samples at ultrastructural resolution within a few days. A fundamental barrier is that the intense X-rays required for imaging also deform and disintegrate the tissue samples. Here we show a combination of solutions that overcome this barrier: We used a cryogenic and stabl

Organic carbon (OC) is a major component of atmospheric particulate matter (PM). Typically OC concentrations are measured using thermal methods such as thermal-optical reflectance (TOR) from samples collected on quartz filters. However, TOR measurements are destructive and expensive. We estimate TOR OC concentrations using Fourier transform infrared (FT-IR) spectra of ambient samples collected on Teflon filter. We have developed a sparse statistical calibration model (ElnetPLS), which excludes unnecessary w

Optical second harmonic generation, thanks to its coherent nature, is a suitable signal for interferometric measurements, such as digital holography: a well-established imaging technique that allows recovering of the complex diffraction wavefields from which it is possible to extract both amplitude- contrast and quantitative phase images. We believe that application of digital holography to non-linear optical fields might ultimately be the key to phase- related functional imaging. In a first approach, we re

We present a method for fast calculation of the electromagnetic field near the focus of an objective with a high numerical aperture (NA). Instead of direct integration, the vectorial Debye diffraction integral is evaluated with the fast Fourier transform for calculating the electromagnetic field in the entire focal region. We generalize this concept with the chirp z transform for obtaining a flexible sampling grid and an additional gain in computation speed. Under the conditions for the validity of the Deby

This paper proposes a new family of bivariate, non-separable splines, called hex-splines, especially designed for hexagonal lattices. The starting point of the construction is the indicator function of the Voronoi cell, which is used to define in a natural way the first-order hex-spline. Higher order hex-splines are obtained by successive convolutions. A mathematical analysis of this new bivariate spline family is presented. In particular, we derive a closed form for a hex-spline of arbitrary order. We also

A novel in situ product removal (ISPR) method that uses microcapsules to ext. inhibitory products from the reaction suspension is introduced into fermn. technol. More specifically, L-phenylalanine (L-phe) was transformed by Saccharomyces cerevisiae to 2-phenylethanol (PEA), which is inhibitory toward the yeast. In order to continuously remove PEA from the vicinity of the cells, the reaction suspension was brought into contact with capsules of 2.2-mm diam. that had a hydrophobic core of di-Bu sebacate and an

This work gives a detailed derivation of the non-retarded dyadic Green's tensor associated with surfaces in the quasistatic approximation. The derivation is made from a rigorous model where the dyadic is expressed as Sommerfeld integrals. We then assess the domain where this approximation can be used for scattering calculations on surfaces by comparing rigorous and non-retarded solutions. Implications of this work for scattering calculations in near-field optics are finally discussed. (C) 2000 Elsevier Scie

The initial dynamics of resonantly excited secondary emission from quantum wells are dominated by Rayleigh scattering due to excitons localized in the disordered quantum well potential. We show experimentally and theoretically how the temporal shape of the early response is related to details of the two-dimensional disorder potential, and we determine the mean amplitude of the fluctuations and the correlation length. Spectral interferometry performed with a. single speckle allows to investigate the phase of

This paper deals with multiwavelets and the different properties of approximation and smoothness that are associated with them. In particular, we focus on the important issue of the preservation of discrete time polynomial signals by multiwavelet based filter banks. We give here a precise definition of balancing for higher degree discrete time polynomial signals and link it to a very natural factorization of the lowpass refinement mask that is the counterpart of the well-known 'zeros at pi' condition on the

The growth and properties of nanosized silicon particles produced by gas-phase reaction in a low-pressure silane plasma has been studied. In situ ion-mass spectroscopy and Mie scattering measurements were used to monitor the formation of powders. High resolution transmission electron microscopic (HREM) studies confirmed the observations made by Raman spectroscopy that the nanoparticles grow from medium range ordered clusters. Onset of crystallization was similar to 700 degrees C when structures ranging from

During the past five years, we have developed in our laboratory a new type of solar cell that is based on a photoelectrochemical process. The light absorption is performed by a monolayer of dye (i.e., a Ruthenium complex) that is adsorbed chemically at the surface of a semiconductor (i.e., titanium oxide (TiO2)). When excited by a photon, the dye has the ability to transfer an electron to the semiconductor. The electric field that is inside the material allows extraction of the electron, and the positive ch

Dark-field optical coherence microscopy

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Multifunctional Dielectric Elastomer Actuator for in vitro Cell Mechanostimulation

Nondestructive X-ray tomography of brain tissue ultrastructure

Analysis of functional groups in atmospheric aerosols by infrared spectroscopy: ElnetPLS model for statistical selection of relevant absorption bands for OC predictions

Digital holographic microscopy at fundamental and second harmonic wavelengths

Fast focus field calculations

Hex-Splines: A Novel Spline Family for Hexagonal Lattices

xxvel type of in situ extraction: Use of solvent containing microcapsules for the bioconversion of 2-phenylethanol from L-phenylalanine by Saccharomyces cerevisiae

Validity domain and limitation of non-retarded Green's tensor for electromagnetic scattering at surfaces

Excitonic dephasing effects studied by time- and phase-resolved secondary emission

High Order Balanced MultiWavelets: Theory, Factorization and Design

Growth, microstructure and sintering behavior of nanosized silicon powders

Nanocrystalline titanium oxide electrodes for photovoltaic applications