Mouse embryonic stem cell sorting for the generation of transgenic mice by sedimentation field-flow fractionation

Mouse embryonic stem (ES) cells are an important tool for generation of transgenic mice and genetically modified mice. A rapid and efficient separation of ES cells that respects cell integrity, viability, and their developmental potential while also allowing purified ES fraction collection under sterile conditions might be of great interest to facilitate the generation of chimeric animals. In this study, we demonstrated for the first time the effectiveness of a sedimentation field-flow fractionation (SdFFF) cell sorter to provide, with a characteristic DNA content, a purified ES cell fraction and with a high in vivo developmental potential to prepare transgenic mice by generation of chimeras having a high percentage of chimerism.     

Elevated lipoprotein (a) levels in primary nephrotic syndrome

Elevated plasma levels of total cholesterol and increase in the hepatic synthesis of some apo B-containing lipoproteins have been noted in the nephrotic syndrome. Apoprotein (a), the apolipoprotein distinguishing lipoprotein (a) [Lp(a)] from low-density lipoprotein, is equally of hepatic origin, and Lp(a) recently has been shown to possess both atherogenic and thrombogenic activities. However, little is known of Lp(a) levels in nephrotic patients. We measured plasma Lp(a) concentrations in 11 patients with primary nephrotic syndrome in the absence of hematuria, hypertension, and renal insufficiency. Histologic lesions were minimal-change disease in five cases, membranous glomerulopathy in four cases, and focal and segmental glomerulosclerosis in two cases. Mean levels of Lp(a) (98 +/- 92 mg/dL [mean +/- SD]) were markedly elevated in the nephrotic patients as compared with the controls (14 +/- 13 mg/dL). No correlation was noted between plasma Lp(a) and proteinuria, albuminemia, total cholesterolemia, low-density lipoprotein cholesterol, apoprotein B100, or plasminogen. Furthermore, there was no correlation between Lp(a) levels and apoprotein (a) isoform size. In four patients, the level of Lp(a) decreased approximately fourfold after remission of the nephrotic syndrome under corticosteroid treatment. Our observation that Lp(a) levels are elevated in the nephrotic syndrome is consistent with the hypothesis that these patients may be at an increased risk of cardiovascular and thrombotic complications.     

First direct calculation of 4f‘ 4f oscillator strengths for dipolar electric transitions in PrCl3

In two previous papers, we interpreted completely the crystal field splitting and Zeeman data of trivalent praseodymium ions in PrCl₃ taking into account configuration interaction between 4f², 4f5d and 4f6p. The obtained eigenvectors are now used to calculate directly the oscillator strengths originating from dipolar electric processes between opposite parity configurations, giving rise to apparent 4f ‘4f transitions. The calculation reproduces in a satisfactory way the absorption from the ground levels toward the ³P₂ and ¹D₂ multiplets but not toward ³P₀ and ³P₁.     

Crystal structure and fluorescence spectrum of 3Y2O3, WO3: Eu3+

A structural study of the rhombohedral compound 3Y₂O₃, WO₃ doped with Europium was carried out. The fluorescence spectrum of Eu³⁺ was measured in the frequency range 12500–25000 cm^?1. Transitions from the excited state 5D₀ to the Stark components of the five lowest 7F_J (J=0,1,2,3,4) states were observed. The analysis revealed that the rare earth ion is within a crystal field of C₁ symmetry. We found values for the B^k_q parameters which give a good agreement between the observed and calculated levels.     

Optical absorption spectrum, oscillator strengths, magnetic splitting factors and paramagnetic susceptibility of Nd doped into LiYO2

Optical and magnetic measurements are performed on Nd³⁺ doped into LiYO₂. 105 energy levels of Nd³⁺ are assigned from the optical absorption and excitation spectra for the powdered sample at 20 K. The crystal field analysis is performed in the C₁ site symmetry of Nd³⁺. Theoretical values of the crystal field parameters, oscillator strengths, magnetic susceptibility and ground state splitting factors are calculated and compared with experimentally measured quantities.     

Hilbert versus Concordia transform for three-phase machine stator current time-frequency monitoring

This paper deals with mechanical fault diagnosis in three-phase induction machines from stator current measurements. According to machine models, mechanical faults lead to amplitude and/or phase modulations of the measured stator current with possibly time varying carrier frequency. The modulation diagnosis requires a univocal definition of the instantaneous phase and amplitude. This is performed by associating a complex signal to the real measured one. For a convenient separate modulation diagnosis, the complex signal instantaneous phase and amplitude are expected to carry, respectively, information about the phase and amplitude modulations. The complex signal is classically obtained through the Hilbert transform. Under Bedrosian conditions, the so-called analytic signal allows a separate modulation diagnosis. However, mechanical faults may also produce fast modulations violating the Bedrosian conditions. This study proposes an alternative complex signal representation which takes advantage of the three stator current measurements available in a three-phase machine. From two stator current measurements, the Concordia transform builds a complex vector, the so-called space vector, which unconditionally allows separate modulation diagnosis. This paper applies and compares the Hilbert and Concordia transforms, theoretically and in case of simulated and experimental signals with various modulation frequency ranges.     

A theoretical and empirical review of the death-thought accessibility concept in terror management research.

Terror management theory (TMT) highlights the motivational impact of thoughts of death in various aspects of everyday life. Since its inception in 1986, research on TMT has undergone a slight but significant shift from an almost exclusive focus on the manipulation of thoughts of death to a marked increase in studies that measure the accessibility of death-related cognition. Indeed, the number of death-thought accessibility (DTA) studies in the published literature has grown substantially in recent years. In light of this increasing reliance on the DTA concept, the present article is meant to provide a comprehensive theoretical and empirical review of the literature employing this concept. After discussing the roots of DTA, the authors outline the theoretical refinements to TMT that have accompanied significant research findings associated with the DTA concept. Four distinct categories (mortality salience, death association, anxiety-buffer threat, and dispositional) are derived to organize the reviewed DTA studies, and the theoretical implications of each category are discussed. Finally, a number of lingering empirical and theoretical issues in the DTA literature are discussed with the aim of stimulating and focusing future research on DTA specifically and TMT in general. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of polyoxyethylated materials on the interaction of surfactants with skin

The effect of surfactants on skin has been investigated by means of two experimental techniques, viz., by permeability studies using isolated neonatal rat stratum corneum membranes, and by studies on the reduction of the electrophysiological potential across freshly excised frog skin membranes. Permeability studies indicate that typical cationic and nonionic surfactants are weak penetrants, unlike anionic surfactants, as exemplified by sodium lauryl sulfate (SLS), which readily penetrates and tends to destroy the integrity of stratum corneum membranes in a matter of hours. The addition of polyethylene glycols (PEG) or nonionic surfactants to solutions of SLS results in a considerable reduction in the last mentioned effects, the reduction tending to increase as the molecular weight and ethylene oxide content of the additive increase. By contrast with permeability, the electrophysiological measurements show that cationic surfactants can be extremely active: the typical surfactant, cetyltrimethyl ammonium bromide (CTAB), at a level of 0.5% in Ringer solution, destroys the potential across frog skin in minutes, and, indeed, is comparable in this respect to SLS. Nonionic surfactants are comparatively inactive, and factant reduces the effect of the latter significantly. Preapplication of a solution of PEG to the membrane, rather than incorporation in the solution of the surfactant, affords better protection against the latter as judged by both permeability and potential criteria.     

High-resolution refractive index anisotropy measurement in optical fibers through phase retardation modulation

We present an improved, high-resolution method for the measurement of phase retardation induced by the material birefringence of optical fibers. Such a method can be used to retrieve information about the spatial distribution of refractive index anisotropy in the fiber by comparing the accumulated phase of a polarization component oriented along the fiber transmission axis and another located in the transverse plane. The method is based on the nonlinear regression of a phase modulated signal of known modulation amplitude altered by the sample. Experimental results obtained with our method for a standard telecommunications fiber (the Corning SMF-28) as well as photosensitive fibers (Fibercore PS1250 and PS1500) are presented with a noise-limited phase resolution below 10(-4) radians and a spatial resolution below 1 microm. An analysis of the limitation of such measurement methods is also presented including diffraction by the fibers.     

Gallium nitride MEMS resonators: how residual stress impacts design and performances

Microsystem Technologies - Starting from Gallium Nitride epitaxially grown on silicon, pre-stressed micro-resonators with integrated piezoelectric transducers have been designed, fabricated, and...