Determination of Optical Constants of Ceria By Combined Analytical and Experimental Approaches

Optical constants of ceria are determined in the visible and near-infrared spectral ranges. Two techniques are employed to obtain the index of refraction. The first technique is a direct procedure which involves analysis of wave interference in the transmission spectrum of a ceria thin film. The second technique is an indirect procedure that involves analysis of transmission and reflection spectrum of ceria with sintered morphology. The index of absorption is obtained in the spectral range of weak absorption using the indirect procedure. The identified index of absorption is in turn used in an alternative approach based on the subtractive Kramers–Krönig relation to estimate the spectral dependence of the index of refraction. The index of refraction identified from the measured transmittance of the thin film is qualitatively consistent with that found in the literature. The subtractive Kramers–Krönig analysis indicates that the spectral dependence of the index of refraction in the transparency range is highly sensitive to the absorption spectrum in the neighboring spectral range of strong absorption, and it is insensitive to the absorption spectrum in the spectral range of weak absorption.     

Magnetic Flux Penetration and Motion in Antiferromagnetic Superconductors

The paper reviews a concept of induced spin-flop domain inside vortices in an antiferromagnetic superconductor. Such phenomenon may occur when an external magnetic field is strong enough to flip over magnetic moments in the core of the vortex from their ground state configuration. The formation of the domain structure inside vortices modifies the surface energy barrier of the superconductor. During this process the entrance of the flux is stopped and a newly created state exhibits perfect shielding. Such behavior should be visible as a plateau on the dependence of flux density as a function of the external magnetic field. The end of the plateau determines the critical field, which has been called the second critical field for flux penetration. Moreover, it is predicted and described how this phenomenon modifies flux creep in layered superconductors. The various scenarios of changing the creep regime from thermal to quantum and vice versa at constant temperature are discussed.     

Reassessment of the number of auxiliary genes essential for expression of high-level methicillin resistance in Staphylococcus aureus

A new transposon library constructed in the background of the highly and homogeneously methicillin-resistant Staphylococcus aureus strain COL yielded 70 independent insertional mutants with reduced levels of antibiotic resistance. Restriction analysis with HindIII, EcoRV, EcoRI, and PstI and then Southern hybridization with probes for the transposon and for the femA-femB gene demonstrated that 41 of the 70 Tn551 mutants carried distinct and novel, as yet undescribed insertion sites, all of which were outside of the mecA gene and were also outside the already-characterized auxiliary genes femA, femB, femC, and femD. All previously described Tn551 mutations of this type were in genes located either on SmaI fragment A or SmaI fragment I. In contrast, inserts of the new library were located in 7 of the 16 SmaI chromosomal fragments, fragments A, B, C, D, E, F, and I. In all of the mutants, expression of methicillin resistance became heterogeneous, and the MIC for the majority of cells was reduced (1.5 to 200 micrograms ml-1) from the homogeneous methicillin MIC (1,600 micrograms ml-1) of the parental cells. Although identification of the exact number of genes inactivated through the new set of transposon inserts will require cloning and sequencing, a rough estimate of this number from mapping data suggests a minimum of at least 10 to 12 new genetic determinants, all of which are needed together with femA, femB, femC, and femD for the optimal expression of methicillin resistance.     

Transport phenomena in thin organic layers

Electronic transport phenomena in thin polycrystalline organic films were studied using transient currents and a.c. techniques. The results obtained for tetracene and p-terphenyl layers are very similar and may be explained by a hopping model. Additional effects are caused by inter-grain barriers. The heights of these barriers (0.07–0.08 eV) are reduced by an external electric field.     

Exploration and avoidance in rats with lesions in amygdala and piriform cortex.

Lesions localized to specific areas of the amygdala and overlying cortex in 41 adult male M?ll-Wistar rats produced differential effects in several behavioral tasks. Three different types of lesions were tested: central, basolateral, and cortex lateral to the amygdala. Lesions restricted to the central nucleus produced increased activity on all parameters studied in an open-field test, but the other 2 groups were not changed. In 1-way active avoidance all 3 groups with lesions showed deficits. The most pronounced change was observed in the central group. All groups showed the same degree of retention loss, but in forced extinction of 1-way active avoidance after retraining, the cortical and basolateral groups were most defective. A fear-reduction hypothesis is proposed for the central lesion. The basolateral and cortical areas may be more specifically involved in passive avoidance behavior. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parameter passing mechanisms and run time data structures

The relationship between parameter passing mechanisms and run time data structures in languages with statically-nested scopes is examined. It is shown that simpler data structures can be used in some cases, with increased efficiency in accessing non-local variables. In particular it is true for the call-by-value-result mechanism, where the usage of displays can be eliminated altogether; however there is some additional cost associated with procedure calls. Under certain conditions the same implementation applies to call-by-reference.     

Decrease of force capabilities as an index of upper limb fatigue

The aim of the study was to assess upper limb fatigue on the basis of the force change index (FCI), which expresses changes in developed force, and to demonstrate that this index differentiates muscle fatigue of the upper limb depending on external load. The study was performed on ten young men in 12 conditions of external load. Ten conditions characterized repetitive work in a two-period cycle, in which both or one of the periods were loaded, and two conditions characterized continuous work with constant load. The participants tried to maintain hand-grip force at an imposed level during a determined time in the standard upper limb posture. Changes in values of recorded force exerted during successive cycles were approximated by a regression function. In most cases there was a strong correlation between the measurement data and the logarithmic regression curve. However, several cases of lower external load showed absence of such correlation. In 75% of the cases, there were statistically significant differences between the values of FCI calculated for individual conditions of external load. That means that FCI not only expresses muscle fatigue quantitatively but also points to the differences in upper limb fatigue resulting from differences in the external load. The study results have shown that the developed index (FCI) can be applied for fatigue assessment and discrimination with a more sophisticated model of a repetitive task than just a simple two-period work and rest model.     

Beam steering experiment with two cascaded ferroelectric liquid-crystal spatial light modulators

The design, construction, and evaluation of a laser beam steerer that uses two binary ferroelectric liquid-crystal (FLC) spatial light modulators (SLMs) operated in conjunction are presented. The system is characterized by having few components and is in principle lossless. Experimentally, a throughput of approximately 20% was achieved. The simple system design was achieved because of the high tilt angle FLC material used in the SLMs, which were specifically designed and manufactured for this study. By coherently imaging the first SLM onto the second SLM, pixel by pixel, we obtained an effective four-level phase structure with a phase step of 90 degrees. An appropriate alignment procedure is presented. The beam steering performance of the system is reported and analyzed.     

Artificial neural network analysis for evaluation of peptide MS/MS spectra in proteomics

The aim of the work was to explore usefulness of artificial neural network (ANN) analysis for the evaluation of proteomics data. The analysis was applied to the data generated by the widely used protein identification program Sequest, completed with several structural parameters readily calculated from peptide molecular formulas. Proteins from yeast cells were identified based on the MS/MS spectra of peptides. The constructed ANN was demonstrated to classify automatically as either "good" or "bad" the peptide MS/MS spectra otherwise classified manually. An appropriately trained ANN proves to be a high-throughput tool facilitating examination of Sequest's results. ANNs are recommended as a means of automatic processing of large amounts of MS/MS data, which normally must be considered in the analysis of complex mixtures of proteins in proteomics.