Interval Δt Research Articles

Deposition-rate dependence of granular size distribution in Cu aggregate on liquid substrate studied by atomic force microscopy

In this article, we report an atomic force microscopy study on the microstructure and the deposition-rate dependence of granular size distribution in copper (Cu) ramified aggregates on a liquid substrate. This study shows that the ramified Cu aggregates are composed of Gaussian size distribution granules, which form immediately after the Cu atoms are deposited. The interesting phenomenon is that the mean diameter Φm of the granules exponentially decays and approaches a stable value Φc with an increase in the deposition rate f. The granular mean diameter Φm slightly changes with the time interval Δt during which the film is kept in the vacuum chamber, owing to the large diffusion coefficient of the Cu granules on the liquid substrates. The experimental behavior strongly depends on the properties of the liquid substrate.

Relation between the Intervals ΔE and Δt Obtained in the De-Excitation Process of Electrons in Metals

A relation between the intervals of energy and time, derived in a former paper and associated with the electron transitions on the Fermi surface of a metal, is examined in comparison with the experimental data. These data are obtained from the de-excitation process of electrons in metals. A comparison between theory and experiment demonstrated that the new relation between energy and time is fitted much better for the experimental results than the well-known relation due to the Heisenberg theory.

Myosin-6 Mobility at the Plasma Membrane of Cultured Mammalian Cells

Myosin-6 is a reverse-directed, actin-based, molecular motor responsible for moving cellular cargo towards the minus-end of actin filaments. It is involved in clathrin-mediated endocytosis and intracellular transport. We have used TIRF microscopy to study the movement and localisation of the “short insert” isoform of eGFP-myosin-6 within live 3T3 fibroblasts and human endothelial cells. Individual GFP tagged myosin-6 particles were automatically tracked by computer. Diffusion of membrane associated proteins is usually controlled by lipid mobility and individual trajectories follow a simple “random walk” in which mean squared displacement (MSD) is proportional to time interval (dT) and the lateral diffusion coefficient.

Winding Actin Filament Paths Provide Mechanistic Insights Into Actomyosin Function

The statistics of heavy meromyosin (HMM) driven actin filament paths in vitro, and thermal fluctuations of actin filaments suspended in a pseudo 2D-space in solution, can be described by the cosine correlation equation (CCE): = exp(-s/[2∗Lp]). Here, θ0) and θs) represent tangent angles at distance 0 and s, respectively from one filament end (in solution) or from the starting point of the path. The quantity Lp is the persistence length (proportional to flexural rigidity) of the filament/path. In vitro motility assay (IVMA) studies (27-29oC) were performed along with studies of actin filaments suspended between two cover-slips in solution. Fits to the CCE gave LP = 16.5 ± 1.7 μm (mean ± 95 % confidence interval) and 11.1 ± 0.6 μm for phalloidin stabilized filaments in solution and propelled by HMM, respectively. In contrast, phalloidin free actin filaments (NHS-rhodamine labeled) exhibited similar LP in solution 10.1 ± 2.1 μm and during HMM propulsion (9.8 ± 0.9 μm). The filament paths were modeled using a Monte-Carlo approach updating angular changes in sliding direction at short time intervals (dt) assuming 1. lateral displacements due to cross-bridge forces and 2. thermal fluctuations of the leading filament end. The results suggest that > 3nm average lateral displacement during each actomyosin interaction would reduce LP by > 30 % compared to that of filaments without HMM. The findings are consistent with the following ideas: 1. Actin filaments exist in two different flexural rigidity states, one favored by myosin binding and the other by phalloidin stabilization, 2. Changes in actin filament flexural rigidity is not required for motion generation. 3. The myosin cross-bridges produce minimal lateral movements (< 3 nm) during the power-stroke.

Relaxation Estimation of RMSD in Molecular Dynamics Immunosimulations

Molecular dynamics simulations have to be sufficiently long to draw reliable conclusions. However, no method exists to prove that a simulation has converged. We suggest the method of “lagged RMSD-analysis” as a tool to judge if an MD simulation has not yet run long enough. The analysis is based on RMSD values between pairs of configurations separated by variable time intervals Δt. Unless RMSD(Δt) has reached a stationary shape, the simulation has not yet converged.

Immune System Modeling and Related Pathologies

Immune System Modeling and Related Pathologies

T and CPT symmetries in entangled neutral meson systems

Genuine tests of an asymmetry under T and/or CPT transformations imply the interchange between in-states and out-states. I explain a methodology to perform model-independent separate measurements of the three CP, T and CPT symmetry violations for transitions involving the decay of the neutral meson systems in B- and Φ-factories. It makes use of the quantum-mechanical entanglement only, for which the individual state of each neutral meson is not defined before the decay of its orthogonal partner. The final proof of the independence of the three asymmetries is that no other theoretical ingredient is involved and that the event sample corresponding to each case is different from the other two. The experimental analysis for the measurements of these three asymmetries as function of the time interval Δt > 0 between the first and second decays is discussed, as well as the significance of the expected results. In particular, one may advance a first observation of true, direct, evidence of Time-Reserval-Violation in B-factories by many standard deviations from zero, without any reference to, and independent of, CP-Violation.In some quantum gravity framework the CPT-transformation is ill-defined, so there is a resulting loss of particle-antiparticle identity. This mechanism induces a breaking of the EPR correlation in the entanglement imposed by Bose statistics to the neutral meson system, the so-called ω-effect. I present results and prospects for the ω-parameter in the correlated neutral meson-antimeson states.

Short range tracking of rainy clouds by multi-image flow processing of X-band radar data

Two innovative algorithms for motion tracking and monitoring of rainy clouds from radar images are proposed. The methods are generalizations of classical optical flow techniques, including a production term (modelling formation, growth or depletion of clouds) in the model to be fit to the data. Multiple images are processed and different smoothness constraints are introduced. When applied to simulated maps (including additive noise up to 10 dB of SNR) showing formation and propagation of objects with different directions and velocities, the algorithms identified correctly the production and the flow, and were stable to noise when the number of images was sufficiently high (about 10). The average error was about 0.06 pixels (px) per sampling interval (ΔT) in identifying the modulus of the flow (velocities between 0.25 and 2 px/ΔT were simulated) and about 1° in detecting its direction (varying between 0° and 90°). An example of application to X-band radar rainfall rate images detected during a stratiform rainfall is shown. Different directions of the flow were detected when investigating short (10 min) or long time ranges (8 h), in line with the chaotic behaviour of the weather condition. The algorithms can be applied to investigate the local stability of meteorological conditions with potential future applications in nowcasting.

Charge trapping-detrapping mechanism of barrier breakdown in MgO magnetic tunnel junctions

Endurance of MgO-based magnetic tunnel junctions has been studied using a time-dependent dielectric breakdown method. Series of successive electrical pulses were applied until electrical breakdown of the tunnel barrier. We show that two electrical breakdown regimes exist depending on the time interval Δt between pulses compared to a characteristic escape time of trapped electrons τ0 ∼ 100 ns. For Δt &amp;lt; τ0, breakdown is caused by a high average charge trapped in the barrier. For Δt &amp;gt; τ0, breakdown is ascribed to large temporal modulation of trapped charges causing alternating stress in the barrier oxide. Between these two regimes, the tunnel junctions reach a very high endurance.

Thermomechanical fatigue of titanium aluminides

This paper reviews the thermomechanical fatigue (TMF) studies performed on various titanium aluminide (TiAl) alloys during the last decade in the research group of one of the authors (H.-J. Christ). The investigated alloys are Ti–47Al–2Mn–2Nb (XD), Ti–46Al–4(Cr,Nb,Ta,B) (γ-MET), Ti–45Al–5Nb–0.2C–0.2B (TNB-V5) and Ti–45Al–8Nb–0.2C (TNB-V2). An interesting result of this comparison is that the materials, though different in chemical compositions, yield comparable TMF behaviour. It can be demonstrated that both out-of-phase (OP) and in-phase (IP) TMF life depend on mean stress σm, which is primarily determined by the temperature-strain phasing, but also strongly affected by total strain amplitude Δε/2, maximum temperature Tmax and temperature interval ΔT – highest mean stresses (i.e. compressive σm in the case of IP-TMF, tensile σm for OP-TMF) resulted in lowest TMF lives. Furthermore, the investigation reveals that the ratio between IP and OP fatigue lives under corresponding conditions can be expressed as a function of the temperature range ΔT. At low values of ΔT the ratio is rather small because the material’s fatigue behaviour approaches isothermal conditions. Higher strain and temperature amplitudes result in very high ratios between IP and OP lives. The influence of cyclic hardening at low temperature during IP-TMF applying a very large ΔT seems to reduce the fatigue life ratio again, because of the rather high stress amplitude established.

The effect of synaptic noise on dendritic morphology

Neurons exhibit enormous diversity in their dendritic morphology and the highly structured dendrites help neurons to perform various computations. The complex relationship between the dendrite morphology and their emergent computational functionality is not well understood and is an active area of research. To study this relationship we previously developed an inverse approach [1] in which model neurons, including dendritic morphology, are optimized to perform a certain computational function. The synaptic inputs in the earlier study were deterministic. However, synaptic noise is known to have profound effects on computations performed by neurons [2]. In this work we investigate the influence of synaptic noise on the optimal morphology to perform a computational task. We consider two types of synaptic noise, namely spatial and temporal noise. The former relates to failure in synaptic transmission while the latter relates to temporal jitter of events. We studied the effect of both types of noise in the input-order detection task. In this task, synaptic inputs are inserted into a model neuron when the dendrites of the model “grow” into two spatially separate regions; the number of synapses depends on the dendritic length in that region. Synapses in both groups are activated sequentially with some interval (Δt) between them. The model neuron is then optimized to respond strongly to a particular order of synaptic activation (for instance, region 1 before region 2) and not in the reverse order. We implement spatial synaptic noise as a probability of synaptic transmission failure, i.e., not all synapses will actually transmit a signal. Temporal synaptic noise is implemented as temporal jitter in the activation of particular synapses. We applied both types of noise in separation and analyzed the resultant morphological structures. Thus, we sought for a morphological mechanism that allows neurons to cope with synaptic noise. We found that different types of synaptic noise yielded different influences on the dendritic morphologies and to different extents. We also compared the results to Nucleus Laminaris neurons--which are assumed to perform a task similar to input-order detection-- and found that model neurons optimized to cope with synaptic noise showed stronger similarity to these neurons than model neurons optimized with deterministic inputs.

A new general approach to determine more accurate comonomer reactivity ratios in controlled/living radical copolymerization systems

In controlled/living radical copolymerization (atom transfer radical copolymerization in this study) and in any other living chain-growth copolymerization, the possible preferential addition of one of the comonomers onto the (macro)initiator-derived (macro)radical can affect the copolymer composition, especially at low conversion; this results in inaccurate comonomer reactivity ratio estimation by the classic approach. A new general approach is introduced in this article, which allowed us to exclude the influence of the possible preferential addition of one of the comonomers onto the (macro)initiator-derived (macro)radical on the copolymer composition at any conversion. According to this approach, copolymer chain grown during time t (t ≠ 0) is considered to be, in fact, the macroinitiator terminated with one of the comonomers under study, which will further grow during the time interval Δt′ = t′ − t [where any reaction time t′ is considered to be grater than reaction time t, i.e. t′ > t] from a comonomer mixture with composition of f(t) [where f(t) is the molar ratio of comonomer i to comonomer j in the comonomer mixture] at time t. In such a situation, it is possible to obtain individual comonomer conversions [xi(Δt′) and xj(Δt′)], the overall comonomer conversion [xov(Δt′)], and the cumulative average copolymer composition for the copolymer formed during Δt′, from which more accurate comonomer reactivity ratios can be calculated by the various low- or high-conversion methods, depending on the overall comonomer conversion. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Change in the Growth Rate of Localized Pancreatic Adenocarcinoma in Response to Gemcitabine, Bevacizumab, and Radiation Therapy on MDCT

To depict treatment response to chemoradiotherapy by comparing tumor growth rate between treated and untreated patients and to compare depicted response with objective response according to the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 guideline. This Health Insurance Portability and Accountability Act-compliant, retrospective study was approved by the institutional review board. Volume doubling time (DT) of histologically confirmed locally advanced pancreatic adenocarcinoma was calculated in 16 patients treated with chemoradiotherapy and 10 untreated patients by incorporating interscan interval (Δt) and tumor volume at baseline (V0) and follow-up (V1) obtained by semiautomated segmentation into the following equation: DT = Δt · log 2/log (V1/V0). Reciprocal of doubling time (RDT), which is the linear representation of tumor growth rate, was calculated by use of the following equation: RDT = 365/DT. The lowest RDT value of 2.42 in untreated patients was considered as the cutoff value for depiction of treatment response. Depicted response rate was defined as the proportion of patients with an RDT value of less than 2.42. Depicted response was compared with objective response according to the RECIST 1.1 guideline. The significance level was set at p < 0.05. There was a significant difference in mean RDT between treated (range, -7.12 to 3.27; mean, -1.27; median, -1.30) and untreated (range, 2.42 to 10.74; mean, 5.33; median, 4.26) patients (p < 0.05). Reciprocal of doubling time was less than 2.42 in 14 treated patients, which corresponded to a depicted response rate of 87.50% as opposed to the objective response rate of 18.75% according to the RECIST 1.1 guideline (p < 0.05) and carbohydrate antigen 19-9 response rate of 62.50% (p > 0.05). Carbohydrate antigen 19-9 response was concordant with RDT and RECIST response in 12 patients (75.00%) (κ, 0.38) and 9 patients (56.25%) (κ, 0.24), respectively. There was a significant difference between depicted response according to RDT and objective response according to RECIST. Reciprocal of doubling time might serve as a valuable biomarker for evaluation of treatment response when depiction of small changes in tumor size is concerned.

The molecular clock in terms of quantum information processing of coherent states, entanglement and replication of evolutionarily selected decohered isomers

Evolutionary pressures have selected quantum uncertainty limits -ΔxΔp ( x ) ≥ 1/2ħ-to operate on metastable amino DNA protons. This introduces a probability of molecular clock arrangement, keto-amino → enol-imine, where product protons are entangled and participate in coupled quantum oscillation at frequencies of ∼ 10(13) s(-1). The ket "seen by" the transcriptase, reading a coherent enol-imine G'-state, is |φ >= α| + + > +β|+- > +γ|-+ > +δ|-->. The transcriptase implements its measurement and generates an output qubit of observable genetic specificity information in an interval Δt ≪ 10(-13) s. These quantum measurements can specify the relative distribution of coherent G'-C' states at time of measurement. The ensuing quantum entanglement between coherent protons and transcriptase units is utilized as a resource to generate proper decoherence and introduce selected time-dependent substitutions, ts, and deletions, td. Topal-Fresco ts are G'202 → T, G'002 → C, *G020(0) → A and *C202(2) → T, whereas td are exhibited at coherent *A-*T sites. Variation in clock 'tic-rate' is a consequence of clock introduction of initiation codons - UUG, CUG, AUG, GUG - and stop codons, UAA, UAG, UGA. Using approximate quantum methods for times t < ∼ 100 y, the probability, P(t), of keto-amino → enolimine arrangement is P ( ρ )(t) = 1/2(γ ( ρ )/ħ)(2) t (2) where γ ( ρ ) is the energy shift. This introduces a quantum Darwinian evolution model which provides insight into biological consequences of coherent states populating human genes, including inherited (CAG)( n ) repeat tracts.

Clustering of ventricular arrhythmic complexes in heart rhythm

We study the statistics of intervals τ between ventricular premature complexes (VPCs) in 24-h electrocardiogram records obtained from PhysioNet data source. We find that the long-term memory inherent in the heartbeat intervals leads to power laws in the probability density function P(τ) between VPCs for τ>6 s. As a consequence, the probability W(t,Δt) that at least one VPC will occur within the next time interval Δt, if the last VPC occurred t time units intervals ago, decays by a power law of t. Based on these results, we suggest a method to obtain a priori information about the occurrence of the next VPC, and how to predict it. We think that usage of this a priori information could be useful for the improvement of the algorithms in healthcare monitoring devices with alarm facilities.

Hypertonic saline solutions do not influence the solubility of sputum from secretor and non-secretor cystic fibrosis patients

IntroductionFunctional alterations of the cystic fibrosis transmembrane conductance regulator gene (CFTR) increase the viscoelasticity of pulmonary secretions of cystic fibrosis (CF) patients and require the use of therapeutic aerosols. The biochemical properties of exocrine secretions are influenced by the expression of the FUT2 gene which determine the secretor and non-secretor phenotypes of the ABH glycoconjugates. The aim of this study was to determine the influence of secretor and non-secretor phenotypes by means of photoacoustic analysis, both the typical interaction time (t 0) and the solubilization interval (Δt) of the sputum of secretor and non-secretor CF patients nebulized by hypertonic saline solutions at different concentrations.Material and methodsSputum samples were obtained by spontaneous expectoration from 6 secretor and 4 non-secretor patients with CF. Each sample was nebulized with 3%, 6%, and 7% hypertonic saline solutions in a photoacoustic cell. The values of t 0 and Δt were determined using the Origin 7.5® computer program (Microcal Software Inc.). The t-test was employed using the GraphPad Instat 3.0® computer program to calculate the mean and standard deviation for each parameter.ResultsFor all hypertonic saline solutions tested, the mean values of t 0 and Δt do not show statistically significant differences between secretor and non-secretor patients.ConclusionsThe secretor and non-secretor phenotypes do not influence the in vitro solubilization of the sputum nebulized by hypertonic saline solutions at different concentrations when analysed by photoacoustic technique.

Variable-range hopping conductivity ofLa1 − xSrxMn1 − yFeyO3

The temperature dependence of the resistivity,ρ, of ceramicLa1 − xSrxMn1 − yFeyO3 (LSMFO)samples with x = 0.3 and y = 0.03, 0.15, 0.20 and 0.25 (or simply #03, #15, #20 and #25, respectively) is investigated between temperaturesT ∼ 5 and 310 K inmagnetic fields B up to 8 T. Metallic conductivity in #03 is changed eventually to activated in #25. In #15 and #20 the behaviorof ρ(T) is more complicated, comprising of two extremes, divided byan interval of metallic behavior in #15, and two inflections ofρ(T) in #20 withinsimilar intervals ΔT below ∼ 100 K.Mott variable-range hopping (VRH) conductivity is observed in #15 above the ferromagnetic Curie temperature,TC. In #20 the Mott VRH conductivity takes place in three different temperature intervals atT > TC,T closeto TC and T < TC. In #25, the Mott VRH conductivity is observed in two different intervals, above and belowTC, divided by an intermediate interval of the Shklovskii–Efros VRH conduction regime.Analysis of the VRH conductivity yielded the values of the localization radius,α, and thedependence of α and of the density of the localized states,g, near the Fermilevel, on B. AboveTC the localization radiusin all samples at B = 0 hassimilar values, α≈1.0–1.2 Å,which is enhanced to α≈3.3 Å (#20) and 2.0 Å (#25) below TC. The sensitivity of α and g toB dependon y andT. Thecomplicated behavior of the mechanisms of the hopping charge transfer, as well as of the microscopicparameters α and g, is attributable to different electronic and magnetic phases of LSMFO varying withtemperature and Fe doping.

Identification of a Residue in Helix 2 of Rice Plasma Membrane Intrinsic Proteins That Influences Water Permeability

Molecular selection, ion exclusion, and water permeation are well known regulatory mechanisms in aquaporin. Water permeability was found to be diverse in different subgroups of plasma membrane intrinsic proteins (PIPs), even though the residues surrounding the water holes remained the same across the subgroups. Upon homology modeling and structural comparison, a conserved Ala/Ile(Val) residue difference was identified in helix 2 that affected the conformation of the NPA region and consequently influenced the water permeability. The residue difference was found to be conservative within the two subgroups of PIPs in rice as well as in other plants. Functional tests further confirmed the prediction via site-directed mutagenesis where replacement of Ala(103) or Ala(102) in respective OsPIP1;1 or OsPIP1;3 with Val yielded 7.0- and 2.2-fold increases in water transportation, and substitution of Ile(98) or Val(95) in respective OsPIP2;3 or OsPIP2;7 with Ala resulted in 73 or 52% reduction of water transportation. Based on structural analyses and molecular dynamics simulations, we proposed that the difference in water permeability was attributed to the orientation variations of helix 2 that modified water-water and water-protein interactions.

EFFECTS OF INDIVIDUAL'S SELF-EXAMINATION ON COOPERATION IN PRISONER'S DILEMMA GAME

We study a spatial evolutionary prisoner's dilemma game on regular network's one-dimensional regular ring and two-dimensional square lattice. The individuals located on the sites of networks can either cooperate with their neighbors or defect. The effects of individual's self-examination are introduced. Using Monte Carlo simulations and pair approximation method, we investigate the average density of cooperators in the stationary state for various values of payoff parameters b and the time interval Δt. The effects of the fraction p of players in the system who are using the self-examination on cooperation are also discussed. It is shown that compared with the case of no individual's self-examination, the persistence of cooperation is inhibited when the payoff parameter b is small and at certain Δt (Δt &gt; 0) or p (p &gt; 0), cooperation is mostly inhibited, while when b is large, the emergence of cooperation can be remarkably enhanced and mostly enhanced at Δt = 0 or p = 1.

A Pure-Jump Transaction-Level Price Model Yielding Cointegration

We propose a new transaction-level bivariate log-price model that yields fractional or standard cointegration. The model provides a link between market microstructure and lower-frequency observations. The two ingredients of our model are a long-memory stochastic duration process for the waiting times, {τk}, between trades and a pair of stationary noise processes, ({ek} and {ηk}), which determine the jump sizes in the pure-jump log-price process. Our model includes feedback between the disturbances of the two log-price series at the transaction level, which induces standard or fractional cointegration for any fixed sampling interval Δt. We prove that the cointegrating parameter can be consistently estimated by the ordinary least squares estimator, and we obtain a lower bound on the rate of convergence. We propose transaction-level method-of-moments estimators of the other parameters in our model and discuss the consistency of these estimators.