Samples Of Different Lengths Research Articles

Reproduction of Images Presented at Different Phases of Alpha Waves

With the aim of confirming the view that the sensitivity of the perceptive apparatus of the cortex changes as the phases of the alpha rhythm alternate, with corresponding changes in the accuracy of visual recognition, online monitoring of changes in wave phases was used for presentation of brief stimuli with high-accuracy timing of delivery at the middle of the alpha-wave rise phase or at the middle of the decay phase. A total of 15 essentially healthy subjects (five men, 10 women) took part in the experiments. Before experiments, subjects performed tests for anxiety, extraversion, and neuroticism. Stimulation was controlled using EEG traces from visual area O2, where alpha-rhythm amplitude is maximal. Performance success (drawing by hand) was compared for presentation of sample lines at different phases of alpha waves. Samples of different lengths were used. Most subjects (14 out of 15) reproduced segments shorter than the samples when stimulation was applied in either wave phase. This was less marked in the decay phase (positivization), i.e., lines were longer and closer to the sample, than in the alpha-wave rise phase (especially for large samples). This difference in stimulation conditions was smaller in subjects with low psychoemotional stability.

X-ray investigation of polytype distribution in InAs nanowires during MBE growth

The monolithic integration of III-V semiconductors with Si is the ideal way to combine the superior optoelectronic properties of the compound semiconductors with the mature Si technology. This integration can be realized by growing epitaxially dislocation-free III-V NWs on Si substrates either in the vapor-liquid-solid (VLS) or in the vapor-solid (VS) mode associated with the presence or absence, respectively, of group-III liquid droplets on the NW tips [1]. In this work, we investigate the correlation between the growth mode and the forming polytypes in InAs NWs grown on Si(111). The growth was performed in the molecular beam epitaxy chamber of beamline 11XU at Spring8 [2], while the structural dynamics was probed by in situ x-ray diffraction. Specifically, the time evolution of the formation of wurtzite (WZ) and zincblende (ZB) polytypes was monitored during the NW growth. Despite the As-rich growth conditions, a spontaneous build-up of liquid In on Si was found to be present in the nucleation phase, where the InAs nuclei mainly grow in the WZ phase with low number of stacking faults. Shortly after the nucleation, the liquid In is consumed by the excessive As, and the growth continues in the VS mode with an increasing density of stacking faults forming in the NW crystal. The time evolution of the liquid Indium signal (Fig. (a)) correlates well with the time evolution of wurzite growth rate (Fig (b)). The latter saturates at a time where the liquid indium disappers, i.e. where the VLS changes into the VS mode, whereas the zinc-blende polytypes grow almost continuous in both VLS and VS growth mode. The dynamics of stacking faults density was determined quantitatively by ex-situ X-ray diffraction measuring thestacking fault induced increase of the peak width of wurtzite reflections at InAs nanowire samples of different length ; i.e. growth time [3].

Scores on Riley’s Stuttering Severity Instrument Versions Three and Four for samples of different length and for different types of speech material

Riley stated that the minimum speech sample length necessary to compute his stuttering severity estimates was 200 syllables. This was investigated. Procedures supplied for the assessment of readers and non-readers were examined to see whether they give equivalent scores. Recordings of spontaneous speech samples from 23 young children (aged between 2 years 8 months and 6 years 3 months) and 31 older children (aged between 10 years 0 months and 14 years 7 months) were made. Riley’s severity estimates were scored on extracts of different lengths. The older children provided spontaneous and read samples, which were scored for severity according to reader and non-reader procedures. Analysis of variance supported the use of 200-syllable-long samples as the minimum necessary for obtaining severity scores. There was no significant difference in SSI-3 scores for the older children when the reader and non-reader procedures were used. Samples that are 200-syllables long are the minimum that is appropriate for obtaining stable Riley’s severity scores. The procedural variants provide similar severity scores.

A Method to Estimate the Necessary Twist Pitch in Multi-filamentary Superconductors

Twisting of multi-filamentary superconductors is an important step in the development of wires with AC losses at an acceptable level for AC applications. The necessary twist pitch depends on wire architecture, critical current density, matrix material, and external factors such as temperature, frequency and applied magnetic field. The development of an AC optimized MgB2 superconductor would be facilitated by a fast method to set the requirements for the twist pitch. A problem often encountered when comparing wires with different twist pitches is the degradation in critical current occurring at small twist pitches due to mechanical deformation. In this work we propose to use a non-twisted conductor to estimate the influence of twisting on the AC losses. A long superconductor is cut into smaller lengths, each simulating one third of the twist pitch, and the AC losses due to applied magnetic fields are compared between samples of different lengths. With this method, the effect of reducing the size of the loop of the coupling currents is studied without changing the superconducting parameters. AC loss measurement results are presented for a round titanium matrix MgB2 wire with simulated twist pitches between 9 mm and 87 mm.

Molecular Dynamics Simulation of C–C Bond Scission in Polyethylene and Linear Alkanes: Effects of the Condensed Phase

The reaction of C-C bond scission in polyethylene chains of various lengths was studied using molecular dynamics under the conditions of vacuum and condensed phase (polymer melt). A method of assigning meaningful rate constant values to condensed-phase bond scission reactions based on a kinetic mechanism accounting for dissociation, reverse recombination, and diffusional separation of fragments was developed. The developed method accounts for such condensed-phase phenomena as cage effects and diffusion of the decay products away from the reaction site. The results of C-C scission simulations indicate that per-bond rate constants decrease by an order of magnitude as the density of the system increases from vacuum to the normal density of a polyethylene melt. Additional calculations were performed to study the dependence of the rate constant on the length of the polymer chain under the conditions of the condensed phase. The calculations demonstrate that the rate constant is independent of the degree of polymerization if polyethylene samples of different lengths are kept at the same pressure. However, if instead molecular systems of different polyethylene chain lengths decompose under the conditions of the same density, shorter chains result in higher pressures and lower rate constants. The observed effect is attributed to a higher degree of molecular crowding (lower fraction of free intermolecular space available for molecular motion) in the case of shorter molecules.

Sample length independent conduction current in polyethylene oxide

The transient current density through ion conducting polyethylene oxide samples of different lengths is measured after application of voltage steps with different amplitudes. In the experiments, it is found that at a given voltage step the long-term current density is independent of the sample length. Qualitatively, the same behavior is attained from computer simulations using a three-dimensional hopping model which takes into account internal ionic charge movements and extrinsic electronic charge injection from the electrodes. It turns out that the width of a depletion zone of mobile ions at the electrode, which only depends on the applied voltage, is responsible for the independence of the current from the sample length.

Demagnetizing correction in permeability measurements of cylinders

A formula for demagnetizing correction of the measured permeability of cylindrical samples is derived. The procedure for using this formula and the accurately calculated fluxmetric demagnetizing factors to treat the results of fluxmetric measurements is introduced and applied to several samples of different lengths cut from the same magnetic cylinder. The revision of ASTM A342, standard test methods for permeability of feebly magnetic materials, is explained in the appendix.

Magnetization and Inter-Filament Contact in HEP and ITER Bronze-Route ${\hbox{Nb}}_{3}{\hbox{Sn}}$ Wires

Magnetization measurements are relevant tests for the characterization of superconductors. Practically they are the only measurements that allow estimating the critical current density at low fields of low temperature superconductors, the effective filament size and the hysteresis losses. For this purpose CERN, in collaboration with the University of Geneva, has carried out magnetization measurements on five types of Nb3Sn wires: three bronze route strands used in the ITER project; one Powder In Tube (PIT) and one Internal Tin (IT) wires used for developing next generation accelerator magnets. The field dependent magnetization has been determined using three setups: a Vibrating Sample Magnetometer (VSM), a Superconducting Quantum Interference Device (SQUID) and a special system used for the production control of LHC strands. Samples of different lengths have been tested to check the different coupling between the filaments. Unexpectedly, it was found that the magnetization of the tested bronze wires was strongly dependent on the sample length. In this paper, the results, which were obtained for different type of strands and sample lengths, are reported and compared.

AC magnetization loss in striated YBCO conductors

Magnetization AC losses in striated YBCO conductors in a perpendicular applied AC magnetic field were investigated with special regard to the coupling current AC loss (CCAC). The AC loss of YBCO samples of different length L was measured by using rectangular-shaped pick-up coils. The AC losses distribution along the length of the tapes was investigated by using short pick-up coils. It was found that CCAC loss per unit length does not depend on the position of the pick-up coil (with respect to the sample centre) and its length. The CCAC loss per unit length scales with the square of the sample length L2 up to the maximal value of longitudinal coupling current of about 0.1•Ic (Ic – critical current).

Does sample length influence the shape of xylem embolism vulnerability curves? A test with the Cavitron spinning technique

The Cavitron spinning technique is used to construct xylem embolism vulnerability curves (VCs), but its reliability has been questioned for species with long vessels. This technique generates two types of VC: sigmoid 's'-shaped and exponential, levelling-off 'r'-shaped curves. We tested the hypothesis that 'r'-shaped VCs were anomalous and caused by the presence of vessels cut open during sample preparation. A Cavitron apparatus was used to construct VCs from samples of different lengths in species with contrasting vessel lengths. The results were compared with VCs obtained using other independent techniques. When vessel length exceeded sample length, VCs were 'r'-shaped and anomalous. Filling vessels cut open at both ends with air before measurement produced more typical 's'-shaped VCs. We also found that exposing segments of 11 woody species in a Cavitron at the pressure measured in planta before sampling considerably increased the degree of embolism above the native state level for species with long vessels. We concluded that open vessels were abnormally more vulnerable to cavitation than intact vessels. We recommend restricting this technique to species with short conduits. The relevance of our conclusions for other spinning techniques is discussed.

Human efficiency for classifying natural versus random text

Humans are remarkably efficient at processing natural text. We quantified efficiency for discriminating a sample of meaningful text from a sample of random text by disrupting the meaningful sample, and measuring how much disruption human readers can tolerate before the two samples become indistinguishable. We performed these measurements for a wide range of conditions, involving samples of different lengths and containing letters, words or Chinese characters. We then compared human performance to the best possible performance achieved by a Bayesian estimator under the conditions in which we tested our participants, and in so doing we determined their absolute efficiency. Values were mostly in the range 5–40%, in agreement with reported efficiencies for many visual tasks. Although not intended as a veridical model of human processing, we found that the Bayesian model captured some (but not all) aspects of how humans classified text in our tasks and conditions.

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EFFECT OF LENGTH ON THE PERFORMANCE OF LEAN NOX TRAPS

The effect of monolith length on the NOx performance of Lean NOx Traps (LNTs) has been investigated using a bench flow reactor (BFR). The composition of the catalyst samples consists of Pt/K supported on y-Al2O3 washcoat. Samples of 2.22-cm in diameter and three different lengths of 2.54, 5.08 and 7.62 cm were evaluated at a fixed gas hourly space velocity (GHSV) using long and short-cycle experiments with only H2, as the reductant in the rich phase, and the NOx performance was compared between samples of different lengths. No significant difference in performance was observed in long and short cycle experiments with full regeneration. On the other hand, significant difference in performance was observed in short-cycle experiments with partial regeneration: the longer the sample the better the performance. The intra-catalyst concentration of H2 measured by a Spatially Resolved Capillary Inlet Mass Spectrometer (SpaciMS) at different axial locations in short-cycle experiments with partial regeneration indicated that higher H2 consumption in shorter samples is responsible for the reduction of NOx performance.

Quantifying uncertainty in mean earthquake interevent times for a finite sample

Seismic activity is routinely quantified using means in event rate or interevent time. Standard estimates of the error on such mean values implicitly assume that the events used to calculate the mean are independent. However, earthquakes can be triggered by other events and are thus not necessarily independent. As a result, the errors on mean earthquake interevent times do not exhibit Gaussian convergence with increasing sample size according to the central limit theorem. In this paper we investigate how the errors decay with sample size in real earthquake catalogues and how the nature of this convergence varies with the spatial extent of the region under investigation. We demonstrate that the errors in mean interevent times, as a function of sample size, are well estimated by defining an effective sample size, using the autocorrelation function to estimate the number of pieces of independent data that exist in samples of different length. This allows us to accurately project error estimates from finite natural earthquake catalogues into the future and promotes a definition of stability wherein the autocorrelation function is not varying in time. The technique is easy to apply, and we suggest that it is routinely applied to define errors on mean interevent times as part of seismic hazard assessment studies. This is particularly important for studies that utilize small catalogue subsets (fewer than ∼1000 events) in time‐dependent or high spatial resolution (e.g., for catastrophe modeling) hazard assessment.

Characterization of bacterial DNA binding to human neutrophil surface

Bacterial DNA activates neutrophils through a CpG- and TLR9-independent mechanism. Neutrophil activation does not require DNA internalization, suggesting that it results from the interaction of bacterial DNA with a neutrophil surface receptor. The aim of this study was to characterize the interaction of bacterial DNA with the neutrophil surface. Bacterial DNA binding showed saturation and was inhibited by unlabeled DNA but not by other polyanions like yeast tRNA and poly-A. Resembling the conditions under which bacterial DNA triggers neutrophil activation, binding was not modified in the presence or absence of calcium, magnesium or serum. Treatment of neutrophils with proteases not only dramatically reduced bacterial DNA binding but also inhibited neutrophil activation induced by bacterial DNA. Experiments performed with DNA samples of different lengths obtained after digestion of bacterial DNA with DNase showed that only DNA fragments greater than ≈170–180 nucleotides competed bacterial DNA binding and retained the ability to trigger cell activation. Treatment of neutrophils with chemoattractants or conventional agonists significantly increased bacterial DNA binding. Moreover, neutrophils that underwent transmigration through human endothelial cell monolayers even in the absence of chemoattractants, exhibited higher binding levels of bacterial DNA. Together, our findings provide evidence that binding of bacterial DNA to neutrophils is a receptor-mediated process that conditions the ability of DNA to trigger cell activation. We speculate that neutrophil recognition of bacterial DNA might be modulated by the balance of agonists present at inflammatory foci. This effect might be relevant in bacterial infections with a biofilm etiology, in which extracellular DNA could function as a potent neutrophil agonist.

Laboratory sound speed measurements on high water content sediment samples

Laboratory measurements of sound speed in fluid viscous materials are known to be difficult, especially for frequencies of a few kHz. An experimental set up which allows such measurements is developed. Tests are run on sediment samples of various lengths (5cm ‐ 20cm), all water‐saturated but with different water contents (or densities). When sound speed only depends on the water content over a narrow frequency bandwidth, its estimation originates from time‐of‐flight measurements on samples of different lengths. It will appear that the water content does play a significant role on the speed of sound. When sound speed depends on frequency (dispersive waves) due to the sediment viscoelastic behaviour, the dependency can be taken into account. An analysis according to the sample length will be given to characterize the sound dispersion for different water contents. It will be shown that both the above studies on the experimental campaign yield sound speed estimations against sample lengths under various hypot...

Ion‐mediated increase in the hydraulic conductivity of Laurel stems: role of pits and consequences for the impact of cavitation on water transport

Changes in hydraulic conductivity (K(h)) were measured in stems of Laurus nobilis L. during perfusion with KCl, NaCl or sucrose solutions. Ionic solutes induced marked increase of K(h) with respect to deionized water but sucrose had no effect. The kinetics of KCl-induced K(h) increase was measured together with changes in [K(+)] of the perfused solution. K(h) increases were paralleled by increases in the [K(+)](out)/[K(+)](in) ratio. Samples of different lengths or with increasing percentage loss of conductivity (PLC) due to xylem cavitation were tested, with the aim of increasing radial flow through intervessel pits. KCl solutions enhanced the K(h) of 12-cm-long samples with a concentration-dependent effect up to 100 mm KCl. DeltaK(h) increased from 3 to 30% in 1.5- and 12-cm-long samples, respectively and remained constant for longer samples. Increasing PLC induced an exponential increase in DeltaK(h). PLC measured with KCl solutions was significantly less than that measured with deionized water, suggesting that measurements of PLC can be affected by the composition of the perfused solution. Experiments support the hypothesis that the 'ionic effect' is mediated by physico-chemical changes of pectins of the pit membranes and raise the possibility that plants might alter the ionic composition of the xylem sap to alleviate the hydraulic impact of cavitation.

Numerical resistivity calculations for disordered three-dimensional metal models using tight-binding Hamiltonians

We calculate the zero-temperature resistivity of model three-dimensional disordered metals described by tight-binding Hamiltonians. Two different mechanisms of disorder are considered: diagonal disorder (random on-site potentials) and off-diagonal disorder (random hopping integrals). The nonequilibrium Green function formalism provides a Landauer-type formula for the conductance of arbitrary mesoscopic systems. We use this formula to calculate the resistance of finite-size disordered samples of different lengths. The resistance averaged over disorder configurations is linear in sample length and resistivity is found from the coefficient of proportionality. Two structures are considered: (1) a simple cubic lattice with one $s$-orbital per site, and (2) a simple cubic lattice with two $d$-orbitals. For small values of the disorder strength, our results agree with those obtained from the Boltzmann equation. Large off-diagonal disorder causes the resistivity to saturate, whereas increasing diagonal disorder causes the resistivity to increase faster than the Boltzmann result. The crossover toward localization starts when the Boltzmann mean free path $l$ relative to the lattice constant $a$ has a value between 0.5 and 2.0 and is strongly model dependent.

Forced Forward Smoldering Propagation in Horizontally Oriented Flexible Polyurethane Foam

A series of experiments was conducted in a small-scale wind tunnel to investigate the effect of forced flow on forward smoldering propagation in flexible polyurethane foam material located horizontally. In the wind tunnel, the air at a flow rate in the range of 0.01-1.5m/s passed over the foam layer surface. Foam samples of different lengths with the same cross-sectional area were studied. From the experimental results, it is seen that the foam length has no clear influence on the smolder propagation velocity. With an increase of air flow rate, firstly, the smolder propagation velocity increases and reaches a maximum at an air flow rate of around 0.8 m/s due to the increased mass transfer of oxygen into the smolder reaction region. It decreases with further increase of air flow rate as heat losses becomes dominant compared to the positive effect of the increase of oxygen transfer into the reaction zone. The variation of the steady smoldering temperature with the air flow rate follows the same trend as that of the smolder propagation velocity. In this paper, a simple analysis is also presented to analyze the co-effect of the mass transfer of oxygen to the smoldering reaction region and the heat loss to the surrounding on the smolder propagation under our current experimental conditions.

Measurement of acoustic impedance and prediction of transmission loss of the porous woven hose in engine intake systems

For the prediction of the acoustic performance of an engine intake system with a porous woven hose, the acoustic wall impedance of the hose should be known. In this paper, a measurement technique is proposed that is valid over the low frequency range in the absence of mean flow. The impedance measurement is performed in two stages. The first stage of impedance measurement is performed in a cylindrical apparatus, within which a short specimen of given ‘porous frequency’ is laid. Because the predicted transmission loss (TL) does not agree with the measured one, due to error in the measured resistance, the second stage of impedance measurement is attempted to estimate the resistance from the measured reactance in the first stage and the measured TL data. Using such new impedance data measured in the second stage for the prediction of TL for samples of different lengths, the agreement between measured and predicted TL is generally improved, as compared to the initial comparison in the first stage. When the curve-fitted impedance for an arbitrary porous frequency is used, it is shown that the measured TL for samples with both arbitrary length and porous frequency generally agree reasonably well with the predicted ones. Exceptions are samples which require the impedance to be extrapolated from measured results, or samples with highly inhomogeneous weaving and coating conditions, and in particular samples with low porous frequency.