In and Si distribution in synthetic opals

An X-ray photoelectric absorption by samples of synthetic opals (SO) loaded by In and Si has yielded filler distribution profiles over thickness. The SO+In sample exhibited a uniform filling of SO voids throughout the sample thickness (on average, 16.9% of each large void). The SO+Si sample, besides the near-surface region where large voids are completely filled, revealed a region with variable Si concentration in the SO, where the Si content decreases linearly down to a depth where pure SO is found. Fiz. Tverd. Tela (St. Petersburg) 40, 1373–1375 (July 1998)     

Cosmological models in general relativity

LRS Bianchi type-I space-time filled with perfect fluid is considered here with deceleration parameter as variable. The metric potentialsA andB are functions of x as well as t. Assuming B′/B = f (x), where prime denotes differentiation with respect to x, it was found thatA = (l′/l)B andB = lS(t), wherel = f (x) andS is the scale factor which is a function of t only. The value of Hubble’s constantH ₀ was found to be less than half for non-flat model and is equal to 1.3 for a flat model     

Preliminary analysis of resonance effect by Helmholtz Schrdinger method

The Helmholtz-Schrdinger method is employed to study the electric field standing wave caused by coupling through a simple slot. There is a good agreement between the numerical results and the resonant conditions presented by the Helmholtz-Schrdinger method. Thus, it can be used in similar cases where the amplitude of the electric field is the important quantity or eigenfunctions of the Schrdinger equation are needed for complicated quantum structures with hard wall boundary conditions.     

Factors that affect the efficiency of antisense oligodeoxyribonucleotide transfection by insonated gas-filled lipid microbubbles

Objective: To investigate the factors that affect the efficiency of antisense oligodeoxyribonucleotide(AS-ODNs) transfection by insonated gas-filled lipid microbubbles. Methods: Lipid microbubbles filled with two types of gases–air and C₃F₈, were prepared respectively. An AS-ODNs sequence HA824 and a breast cancer cell line SK-BR-3 were used to define the various operating variables determining the transfection efficiency of insonated microbubbles. Two mixing methods, three levels of mixing speed, different mixing durations and various ultrasound initiation time after mixing were examined respectively. Transfection efficiency was detected by fluorescence microscopy. Results: C₃F₈ microbubbles gave higher levels of AS-ODNs transfection efficiency than air microbubbles in all test conditions. Transfection efficiency resulted from mixing method A (incubation of HA824 and microbubbles before mixing cells) did not show significant difference with that of mixing method B (without incubation of HA824 and microbubbles before mixing cells). Mixing speed, duration of mixing and ultrasound initiation time after mixing were central to determining HA824 transfection efficiency in vitro. The optimum parameters for SK-BR-3 cells were found at a mixing speed of 40–50 rpm for 30–60 s with less than 60 s delay before ultrasound. Conclusion: Ultrasound-mediated AS-ODNs transfection enhanced by C₃F₈–filled lipid microbubbles represents an effective avenue for AS-ODNs transfer.     

Thymic Selection of T Cells as Diffusion with Intermittent Traps

T cells orchestrate adaptive immune responses by recognizing short peptides derived from pathogens, and by distinguishing them from self-peptides. To ensure the latter, immature T cells (thymocytes) diffuse within the thymus gland, where they encounter an ensemble of self-peptides presented on (immobile) antigen presenting cells. Potentially autoimmune T cells are eliminated if the thymocyte binds sufficiently strongly with any such antigen presenting cell. We model thymic selection of T cells as a random walker diffusing in a field of immobile traps that intermittently turn “on” and “off”. The escape probability of potentially autoimmune T cells is equivalent to the survival probability of such a random walker. In this paper we describe the survival probability of a random walker on a d-dimensional cubic lattice with randomly placed immobile intermittent traps, and relate it to the result of a well-studied problem where traps are always “on”. Additionally, when switching between the trap states is slow, we find a peculiar caging effect for the survival probability.     

SNR phase order k-space encoding (SPOKE)

A method of determining the phase-encode order for MR Fourier-encoded imaging is described, which provides an additional option for optimizing images from samples with signals that change during data acquisition. Examples are in hyperpolarized helium gas imaging of the lungs where polarization is lost with each RF pulse or the signal changes observed in rapid dynamic studies with T₁ or T₂* contrast agents when mixing is taking place. The method uses a single frequency-encoded projection in the proposed phase-encoding direction. The projection is subsequently sorted into signal-to-noise ratio (SNR) order. The indices of the sorted array are then used to create the phase-encode table to be used for the scan. This phase table is sorted in descending SNR order for signals that decrease during data acquisition and in ascending order for signals that increase during data acquisition. Simulations suggest that this technique can produce higher resolution than centric-ordered phase encoding at the expense of increased modulation (ghosting) artifact for dynamically changing signals. Initial practical implementation of the technique has been carried out on a dedicated 0.2-T Niche MR system, and the test object results agree well with simulations. Hyperpolarized 3-He lung images have also been acquired and postprocessed using the SNR phase order k-space encoding (SPOKE) methodology and show potential for improved imaging with high flip angles where polarization is rapidly lost. Applications may also be found for 3D volumetric acquisitions where two dimensions can be SPOKE encoded.     

Dimensional analysis of aqueous magnetic fluids

A comparison of the synthesis and characterization of three aqueous magnetic fluids intended for biomedical applications is presented. Stable colloidal suspensions of iron oxide nanoparticles were prepared by a co-precipitation method with the magnetite cores being coated with β-cyclodextrin, tetramethylammonium hydroxide and citric acid. Rheological properties of the fluids were investigated, i.e. viscosity (capillary method) and surface tension (stalagmometric method) in correlation with their density (picnometric method). The dimensional distributions of the ferrophase particles physical diameter of these three magnetic fluids – revealed on the basis of transmission electron microscopy (TEM) data – as well as the diameter distributions of some other magnetic fluids presented in the literature, were comparatively analyzed using the box-plot statistical method. In order to extract complementary data on the magnetic diameter of an iron oxide core, magnetization measurements as well as X-ray diffraction pattern analysis were carried out. Interpretation of all the measurement data was accomplished by assessing the suitability of the three magnetic fluid samples from the viewpoint of their stability and biocompatibility. PACS 75.50.Mm; 61.46.Df; 68.37.Lp; 96.15.Pf; 75.75.+a     

Forward analysis of πN scattering with an expansion method

The π N forward-scattering data are analyzed using an expansion method, where the invariant amplitudes are represented by expansions satisfying the forward dispersion relations. The experimental errors of the data are taken into account through the covariance matrix of the coefficients of the expansions in a careful error analysis. From the results, some coefficients, c _n0 ^± , of the subthreshold expansions have been calculated with proper error bars.     

Flexo-electric polarization and anchoring energy for a nematic liquid crystal in a hybrid cell

Summary The flexo-electric polarization of hybrid nematic cells filled with 5 CB was measured as a function of cell thickness. To this aim the pyroelectric response of a nematic layer with small amount of light absorbing dye dissolved was detected in a nematic temperature range. From the experimental data the angle of the director deviation at the homeotropic boundary was calculated as a function of cell thickness. This dependence allows the qualitative determination of the shape of the potential well for the director deviation which is inconsistent with Rapini’s sinesquared form. The ?apparent? Rapini’s anchoring energy varies with a surface director angle (at the homeotropic boundary) from 5·10⁻³ to 3.5·10⁻² erg·cm⁻². Work presented at the second USSR-Italy Bilateral Meeting on Liquid Crystals held in Moscow, September 15–21, 1988.     

Estimation of parameters of an alternate stream of events in “dead” time conditions

An alternate stream of events is examined in circumstances where each successive event gives rise to some unobservability period (“dead” time) of fixed duration during which other events are unobservable. The parameters of the alternate stream of events are estimated by the moment method. The dead time estimate is chosen empirically. Confidence intervals for the estimates are constructed using the data from a statistical experiment. Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 8–13, April, 1999.     

TDPAC Study of the Hydrogen Uptake Process in HfNi

The electronic properties of the HfNi-hydrogen system has been investigated, as a function of the hydrogen composition ratio (x), using combined Time Differential Perturbed Angular Correlation (TDPAC) technique and standard full-potential Linearized-Augmented-Plane-Wave method. The experimental TDPAC data confirm the presence of a two-step hydrogenation process in this system, with the octahedral holes filled first. The major part of the electric field gradient at the hafnium site is from p–p contribution, shifted down in energy by hydrogen s-states contribution.     

Various Shapes of 3 D Resonators Pass-Band Filters

The integral equations technique based on a three dimensional finite element method is applied as a quick and accurate analysis tool for the design of microwave passband filters. A three resonator H-plane bandpass filters with the various shapes of cavities and the irises are analyzed with this method in a single step and for only one mode, take into account all the electromagnetic effects. Consequently, it consumes less memory and CPU time. We propose also to study the same filters filled by homogeneous high dielectric material (ε_τ = 9.6) for Both resonator and coupling section. All these numerical results have been validated through a comparison with the results available in the scientific literature.     

Rubber friction: Comparison of theory with experiment

We have measured the friction force acting on a rubber block slid on a concrete surface. We used both unfilled and filled (with carbon black) styrene butadiene (SB) rubber and have varied the temperature from −10 °C to 100 °C and the sliding velocity from 1 μm/s to 1000 μm/s. We find that the experimental data at different temperatures can be shifted into a smooth master-curve, using the temperature-frequency shifting factors obtained from measurements of the bulk viscoelastic modulus. The experimental data has been analyzed using a theory which takes into account the contributions to the friction from both the substrate asperity-induced viscoelastic deformations of the rubber, and from shearing the area of real contact. For filled SB rubber the frictional shear stress σ_f in the area of real contact results mainly from the energy dissipation at the opening crack on the exit side of the rubber-asperity contact regions. For unfilled rubber we instead attribute σ_f to shearing of a thin rubber smear film, which is deposited on the concrete surface during run in. We observe very different rubber wear processes for filled and unfilled SB rubber, which is consistent with the different frictional processes. Thus, the wear of filled SB rubber results in micrometer-sized rubber particles which accumulate as dry dust, which is easily removed by blowing air on the concrete surface. This wear process seams to occur at a steady rate. For unfilled rubber a smear film forms on the concrete surface, which cannot be removed even using a high-pressure air stream. In this case the wear rate appears to slow down after some run in time period.     

Bianchi Type-III Cosmological Models with Time Dependent Displacement Vector for Barotropic Fluid Distribution in Lyra Geometry

Bianchi Type-III cosmological models for perfect fluid distribution with time dependent displacement field in the framework of Lyra geometry are investigated. To get the deterministic model of the universe, we have assumed two conditions (i) shear (σ) is proportional to the expansion (θ). This leads to B=C ⁿ where B and C are metric potentials and n is a constant. (ii) Universe is filled with barotropic fluid distribution which leads to p=γ ρ, 0≤γ≤1, p being isotropic pressure and ρ the energy density. The physical and geometrical aspects of the model with a special case and singularities in the models are also discussed.     

Epithelial tissue statistics: Eliminating bias reveals morphological and morphogenetic features

Geometric order in quasi-two-dimensional epithelia has been extensively researched in order to identify and classify different tissues to help our understanding of how tissues form (morphogenesis) and how their formation may be influenced (tissue regeneration). However, the significance of published data —such as the distribution of numbers of cell neighbors— has been debatable because of measurement bias. We shown that such bias can be detected and corrected without detailed knowledge of the original samples, using only the biased (measured) distributions. This is true for both of the most important sources of bias: the measurement of apparent four-fold vertices and the selective preference for measuring smaller cells introduced by selecting a finite sampling window. The resulting unbiased data allows for a meaningful comparison of all available data, from different sources, taken with different experimental resolution and methodology. Conclusive evidence is found that the apparent four-fold vertices are neither distributed randomly nor oriented randomly, revealing profound differences in topological correlation between proliferating and remodeling tissues. The method is applied to measurements of Drosophila wing tissue, where it successfully disentangles distributional moments, allowing for an assessment of their relative importance, independence, and significance in tissue identification and classification.     

Shape measurement for BGA using whole-space tabulation method with FPGA memory board

Whole-space tabulation method (WSTM) is a technique to relate the phase of a projected grating and the coordinates at each pixel of a camera. The relation data of all the pixels are obtained in the whole-space where a reference plane is moved. The relation data are stored in tables. Thereby, WSTM is high speed and accurate shape measurement method because the coordinates are obtained by only looking up the tables without any complex calculation. Even when the brightness distribution of the projected grating is warped from a cosinusoidal wave, correct coordinates are provided. However, the WSTM needs huge memories for the phase-coordinate tables such as 10 GB in the case of a VGA image and 2000 tables at each pixel. Therefore, we developed an FPGA memory board to store the table and to refer the table in real-time. In the case of a ball grid array (BGA), it is necessary to measure the shape of the balls with high accuracy and high speed without the influence of halation. It is also necessary to measure the coplanarity of the balls without distortion. The influence of halation can be reduced with combining the 3D shape measured with several cameras set at different positions. It is easy to realize them using the WSTM. In this paper, it is confirmed that accurate shape measurements for a BGA can be performed using the WSTM with an FPGA memory board.     

The generation of intense, transform-limited laser pulses with tunable duration from 6 to 30 fs in a differentially pumped hollow fibre

We have investigated experimentally the energy transmission and spectral broadening of 30-fs, 700-μJ laser pulses in a neon-filled, 250-μm inner diameter hollow fibre. We implement a differentially pumped fibre, where a vacuum is maintained at the fibre entrance, and compare this to a statically filled fibre. We obtain significantly higher transmission and increased spectral broadening in the differentially pumped case due to a reduction of ionisation defocusing at the fibre entrance. This arrangement provides a method for the generation of near-transform- limited pulses with smoothly varying pulse duration whilst maintaining constant pulse energy, by simple adjustment of the gas pressure. Compression of ∼450-μJ pulses from the differentially pumped fibre to a duration of 6.5 fs has been achieved for pulses with spectra spanning 650–900 nm, by use of negatively dispersive chirped mirrors. PACS 42.65.Re; 42.65.Jx; 42.65.-k     

Photoacoustic measurement of N2O concentrations in ambient air with a pulsed optical parametric oscillator

Photoacoustic spectroscopy, in combination with a pulsed grazing-incidence optical parametric oscillator (GIOPO), was used for sensitive detection of nitrous oxide (N₂O) in ambient air. The ν₁+ν₃ combination band of N₂O was excited with the idler beam of the GIOPO in the 2.76 μm–2.91 μm spectral region, where CO₂ and water-absorption lines are also present. Three chemical filters filled with KOH, CaCl₂, and P₂O₅ were used to reduce the CO₂ and water concentrations to the level of several parts per billion (10⁹) by volume (ppbv). Photoacoustic spectra containing several absorption lines were recorded and the concentration was determined by an integral evaluation method and a fast Fourier transform evaluation method. The photoacoustic signal was calibrated by a standard mixture of 50.6 parts per million by volume (ppmv) of N₂O in synthetic air. Values of 311±5 ppbv, 314±5 ppbv, and 316±5 ppbv were found for three ambient samples collected at nearby roads. PACS 42.62.Fi; 42.65.Yj; 07.07.Df; 42.68.Ca     

The NUBASE2016 evaluation of nuclear properties

This paper presents the NUBASE2016 evaluation that contains the recommended values for nuclear and decay properties of 3437 nuclides in their ground and excited isomeric(T_(1/2)≥100 ns) states.All nuclides for which any experimental information is known were considered.NUBASE2016 covers all data published by October 2016 in primary(journal articles) and secondary(mainly laboratory reports and conference proceedings) references,together with the corresponding bibliographical information.During the development of NUBASE2016,the data available in the "Evaluated Nuclear Structure Data File"(ENSDF) database were consulted and critically assessed for their validity and completeness.Furthermore,a large amount of new data and some older experimental results that were missing from ENSDF were compiled,evaluated and included in NUBASE2016.The atomic mass values were taken from the "Atomic Mass Evaluation"(AME2016,second and third parts of the present issue).In cases where no experimental data were available for a particular nuclide,trends in the behavior of specific properties in neighboring nuclides(TNN) were examined.This approach allowed to estimate values for a range of properties that are labeled in NUBASE2016 as "non-experimental"(flagged "#").Evaluation procedures and policies used during the development of this database are presented,together with a detailed table of recommended values and their uncertainties.     

Measurement and QCD analysis of the diffractive deep-inelastic scattering cross section at HERA

A detailed analysis is presented of the diffractive deep-inelastic scattering process ep→eXY, where Y is a proton or a low mass proton excitation carrying a fraction 1-x_IP>0.95 of the incident proton longitudinal momentum and the squared four-momentum transfer at the proton vertex satisfies |t|<1 GeV². Using data taken by the H1 experiment, the cross section is measured for photon virtualities in the range 3.5≤Q²≤1600 GeV², triple differentially in x_IP, Q² and β=x/x_IP, where x is the Bjorken scaling variable. At low x_IP, the data are consistent with a factorisable x_IP dependence, which can be described by the exchange of an effective pomeron trajectory with intercept α_IP(0)=1.118±0.008(exp.)^+0.029 _-0.010(model). Diffractive parton distribution functions and their uncertainties are determined from a next-to-leading order DGLAP QCD analysis of the Q² and β dependences of the cross section. The resulting gluon distribution carries an integrated fraction of around 70% of the exchanged momentum in the Q² range studied. Total and differential cross sections are also measured for the diffractive charged current process e⁺p→ν̄_eXY and are found to be well described by predictions based on the diffractive parton distributions. The ratio of the diffractive to the inclusive neutral current ep cross sections is studied. Over most of the kinematic range, this ratio shows no significant dependence on Q² at fixed x_IP and x or on x at fixed Q² and β.