Residual stresses in the graded interlayer between W and CuCrZr alloy

Journal of Materials Science - One of the big challenges for realizing future nuclear fusion reactors is the development of materials able to withstand the high thermal loads and particle fluxes...     

Alterations of microsatellites in neurofibromas of von Recklinghausen's disease

von Recklinghausen's disease, or type I neurofibromatosis, a common familial tumor syndrome, is characterized by the occurrence of multiple benign neoplasms of nerve sheath cells. The disease is caused by germ-line mutations of the NF1 gene, which encodes a member of the GTPase-activating superfamily of Ras regulatory proteins. We analyzed 5 dinucleotide repeat loci in DNAs from neurofibromas and matched normal skin from 16 NF1 patients. Eight cases (50%) manifested microsatellite alterations. Expansions or compressions of dinucleotide repeats were observed at one locus in four cases and at two loci in one case. Banding patterns compatible with the loss of a microsatellite allele were observed in four cases, including one that also presented microsatellite instability. The surprisingly high frequency of microsatellite alterations suggests that the NF1 gene or another gene(s) contributing to the pathogenesis of neurofibromas might be directly or indirectly implicated in the control of genomic integrity.     

Free-electron laser operation in the intermediate gain region

The modification induced on the well-known antisymmetric gain function of a free-electron laser when the gain coefficient g ₀ ranges up to 10 is studied. Deviations from the linear regime for g₀⩾0.5 are presented, and a simple perturbative analysis which accounts remarkably well for the corrections to the linear gain formula even for g₀=10 is discussed. The effect of inhomogeneous broadening is also discussed     

X-ray microscopy of plant cells by using LiF crystal as a detector

A lithium fluoride (LiF) crystal has been utilized as a new soft X-ray detector to image different biological samples at a high spatial resolution. This new type of image detector for X-ray microscopy has many interesting properties: high resolution (nanometer scale), permanent storage of images, the ability to clear the image and reuse the LiF crystal, and high contrast with greater dynamic range. Cells of the unicellular green algae Chlamydomonas dysosmos and Chlorella sorokiniana, and pollen grains of Olea europea have been used as biological materials for imaging. The biological samples were imaged on LiF crystals by using the soft X-ray contact microscopy and contact micro-radiography techniques. The laser plasma soft X-ray source was generated using a Nd:YAG/Glass laser focused on a solid target. The X-ray energy range for image acquisition was in the water-window spectral range for single shot contact microscopy of very thin biological samples (single cells) and around 1 keV for multishots microradiography. The main aim of this article is to highlight the possibility of using a LiF crystal as a detector for the biological imaging using soft X-ray radiation and to demonstrate its ability to visualize the microstructure within living cells.     

High-resolution water window X-ray imaging of in vivo cells and their products using LiF crystal detectors

High contrast imaging of in vivo Chlorella sorokiniana cells with submicron spatial resolution was obtained with a contact water window X-ray microscopy technique using a point-like, laser-plasma produced, water-window X-ray radiation source, and LiF crystals as detectors. This novel type of X-ray imaging detectors is based on photoluminescence of stable electronic point defects, characterized by high intrinsic resolution. The fluorescence images obtained on LiF crystals exposed in single-shot experiments demonstrate the high sensitivity and dynamic range of this new detector. The powerful performances of LiF crystals allowed us to detect the exudates of Chlorella cells in their living medium and their spatial distribution in situ, without any special sample preparation.     

A 7 Mbyte/s (65 MHz), mixed-signal, magnetic recording channel DSPusing partial response signaling with maximum likelihood detection

A mixed-signal, 7.0 Mbyte/s PRML (partial-response maximum likelihood) read/write channel is discussed in this paper. PR-IV (minimum signal bandwidth) for signal encoding is used, along with ML (maximum likelihood) detection to achieve superior error rate performance. Signal equalization is provided using a programmable ten-tap FIR (finite impulse response) digital filter. This read/write channel is implemented on a single chip using analog circuits and 20 K CMOS logic gates. The 7.5 mm square chip uses a 5 V, 1 μm, BiCMOS process with a 6 GHz n-p-n and a 1 GHz p-n-p and is packaged in a 100-lead metal QFPK (quad flat pack)     

Quantum statistical properties of an FEL amplifier

We discuss the problem of photon quantum statistics of a single particle free-electron laser (FEL) amplifier in the small-signal cold beam regime to first order in the electron quantum recoil. The initial radiation wave is an arbitrary coherent state. We show that Glauber coherence is not preserved by the FEL interaction if the initial coherent state is not the vacuum, even if we neglect the electron quantum recoil (absence of gain). We evaluate the first two moments of the final photon distribution and find sub- (super)-Poissonian photon statistics for a negative (positive) resonance parameter.