Short Time Limit Research Articles

Amperometric Glucose Biosensor Based on Integration of Glucose Oxidase with Palladium Nanoparticles/Reduced Graphene Oxide Nanocomposite

We report on a new type of amperometric glucose biosensor that was made by integration of glucose oxidase (GOD) with palladium nanoparticles/reduce graphene oxide (Pd/RGO) nanocomposite. The Pd/RGO was prepared by a one-step reduction method in which the palladium nanoparticles and the reduced graphene oxide (RGO) were simultaneously accomplished from the reduction of dispersed solution of PdCl2 and graphite oxide (GO) with hydrazine. The asprepared nanocomposite exhibits favorable electrocatalytic activities towards the oxidation of H2O2, which makes it a good platform for the construction of the glucose biosensor. The analytical performance of the glucose biosensor is fully evaluated. It shows good analytical properties in terms of a short response time (3 s), high sensitivity (14.1 μA/mM), and low detection limit (0.034 mM). In addition, the effects of pH value, applied potential, electroactive interference and the stability of the biosensor were discussed as well.

Development of a Dynamic Intelligent Speed Adaptation (ISA)

Intelligent speed adaptation (ISA) is a promising technology to dynamically limit vehicles speed. Indeed, it can provide the authorized speed limits values to the drivers. The interest of this kind of system is its embedded character in order to inform drivers in live. That's why it is important to implement it into a cheap and available technology like a smartphone. However, because the smartphone GPS positioning are often inaccurate, the displayed speed may be wrong. This paper presents a process to determine the speed limit values by matching a vehicle real road-network position with a map and a database. It combines a predictive model of movement in order to limit instants without informations, an In-of-Order Kalman filter which corrects the GPS measurements and takes account of variable sampling time and finally an online map-matching algorithm based on several weighting parameters. The system will be qualified of “dynamic” because it has the advantage to display short-time speed limits. Simulation results and experimental results will also be included.

A ‘reciprocal’ theorem for the prediction of loads on a body moving in an inhomogeneous flow at arbitrary Reynolds number – CORRIGENDUM

In Magnaudet (2011) an inertial contribution was overlooked during the derivation of (3.6). Indeed, when generalizing (E.5), which is valid for an irrotational velocity field $\tilde {\mathbi{U}} = \boldsymbol{\nabla} \tilde {\Phi } $, to (E.6) which holds for any velocity $\tilde {\mathbi{U}} $, an extra term $\int \nolimits \nolimits _{\mathscr{V}} (\tilde {\mathbi{U}} \ensuremath{-} \boldsymbol{\nabla} \tilde {\Phi } )\boldsymbol{\cdot} (\boldsymbol{\nabla} {\mathbi{U}}_{U} { \mathop{ + }\nolimits }^{T} \boldsymbol{\nabla} {\mathbi{U}}_{U} )\boldsymbol{\cdot} \hat {\mathbi{U}} \hspace{0.167em} \mathrm{d} V$ arises on the right-hand side of the latter and hence on that of (E.8). Therefore the right-hand side of (3.6) actually involves an additional contribution $\ensuremath{-} 2\int \nolimits \nolimits _{\mathscr{V}} (\tilde {\mathbi{U}} \ensuremath{-} \boldsymbol{\nabla} \tilde {\Phi } )\boldsymbol{\cdot} {\mathbi{S}}_{\mathbi{U}} \boldsymbol{\cdot} \hat {\mathbi{U}} \hspace{0.167em} \mathrm{d} V$, where ${\mathbi{S}}_{\mathbi{U}} = 1/ 2(\boldsymbol{\nabla} {\mathbi{U}}_{U} { \mathop{ + }\nolimits }^{T} \boldsymbol{\nabla} {\mathbi{U}}_{U} )$ denotes the strain-rate tensor associated with the undisturbed flow field. This contribution to the force and torque results from the distortion by the underlying strain rate of the vortical velocity disturbance $\tilde {\mathbi{U}} \ensuremath{-} \boldsymbol{\nabla} \tilde {\Phi } $ generated either by the dynamic boundary condition at the body surface ${S}_{B} $ (and possibly on the wall ${S}_{W} $), or/and by the vorticity ${\boldsymbol{\omega} }_{\mathbi{U}} $ of the undisturbed flow within the core of the fluid. This extra term gives in turn rise to an additional contribution $\ensuremath{-} 2\int \nolimits \nolimits _{\mathscr{V}} (\tilde {{\mathbi{U}}_{0} } \ensuremath{-} \boldsymbol{\nabla} {\tilde {\Phi } }_{0} )\boldsymbol{\cdot} {\mathbi{S}}_{\mathbi{0}} \boldsymbol{\cdot} \hat {\mathbi{U}} \hspace{0.167em} \mathrm{d} V$ on the right-hand side of (3.13)–(3.15). This term was not present in the inviscid expressions established by Miloh (2003) because his derivation was restricted to situations in which the velocity disturbance is irrotational throughout the flow domain. This extra term does not alter the conclusions brought in the present paper for inviscid two-dimensional flows, nor those corresponding to the short-time limit of inviscid three-dimensional flows. In the limit $Re\ensuremath{\rightarrow} \infty $ considered in the example of § 4.3, the disturbance is still irrotational outside the boundary layers that develop around the bubble and along the wall, respectively. The leading order in the vortical velocity disturbance is of $O(R{e}^{\ensuremath{-} 1/ 2} )$ around the bubble, both in the ${\mathbi{e}}_{\parallel } $ and ${\mathbi{e}}_{\perp } $ directions. Near the wall, it is of $O({\kappa }^{2} )$ (respectively $O({\kappa }^{2} R{e}^{\ensuremath{-} 1/ 2} )$) in the ${\mathbi{e}}_{\parallel } $ (respectively ${\mathbi{e}}_{\perp } $) direction. Since the thickness of both boundary layers is of $O(R{e}^{\ensuremath{-} 1/ 2} )$ and $\hat {\mathbi{U}} \boldsymbol{\cdot} {\mathbi{e}}_{\perp } $ grows linearly with the distance to the wall, the extra term $\ensuremath{-} \ensuremath{\alpha} \int \nolimits \nolimits _{\mathscr{V}} \{ (\tilde {{\mathbi{U}}_{0} } \ensuremath{-} \boldsymbol{\nabla} {\tilde {\Phi } }_{0} )\boldsymbol{\cdot} {\mathbi{e}}_{\perp } (\hat {\mathbi{U}} \boldsymbol{\cdot} {\mathbi{e}}_{\parallel } )$$+ (\tilde {{\mathbi{U}}_{0} } \ensuremath{-} \boldsymbol{\nabla} {\tilde {\Phi } }_{0} )\boldsymbol{\cdot} {\mathbi{e}}_{\parallel } (\hat {\mathbi{U}} \boldsymbol{\cdot} {\mathbi{e}}_{\perp } )\} \hspace{0.167em} \mathrm{d} V$ yields an $O(\ensuremath{\alpha} R{e}^{\ensuremath{-} 1} )$ net contribution provided by the bubble boundary layer and only an $O(\ensuremath{\alpha} {\kappa }^{2} R{e}^{\ensuremath{-} 1} )$ correction provided by the wall boundary layer. Hence the inviscid predictions (4.26) and (4.33) are unchanged and there is an $O(\ensuremath{\alpha} R{e}^{\ensuremath{-} 1} )$ correction to the viscous drag and lift, similar in magnitude to that resulting from the term $\ensuremath{-} \int \nolimits \nolimits _{\mathscr{V}} \hat {\phi } {\boldsymbol{\omega} }_{0} \boldsymbol{\cdot} \mathop{ (\tilde {\boldsymbol{\omega} } + {\tilde {\boldsymbol{\omega} } }_{B} )} \nolimits _{0} \hspace{0.167em} \mathrm{d} V$. Owing to the weak inhomogeneity assumption invoked in §§ 3.2 and 4.3, the dimensionless shear rate $\ensuremath{\alpha} $ must be much smaller than unity for (4.26) and (4.33) to hold. Hence, in this context, the above corrections to the drag are much smaller than the leading, $O(R{e}^{\ensuremath{-} 1} )$, contribution provided by the surface term $R{e}^{\ensuremath{-} 1} \int \nolimits \nolimits _{{S}_{B} } \{ (\hat {\mathbi{U}} \ensuremath{-} {\mathbf{e} }_{\parallel } )\ensuremath{\times} \boldsymbol{\omega} \} \boldsymbol{\cdot} \mathbi{n}\hspace{0.167em} \mathrm{d} S$. Note that the above $R{e}^{\ensuremath{-} 1} $ prefactor is missing on the right-hand side of (4.16) and (4.19).

On the design of online synchronous assessments in a synchronous cyber classroom

AbstractOnline learning has been rapidly developing in the last decade. However, there is very little literature available about the actual adoption of online synchronous assessment approaches and any guidelines for effective assessment design and implementation. This paper aims at designing and evaluating the possibility of applying online synchronous assessments in a formal credit course. Relying on the four dimensions of knowledge taxonomy, this paper describes four different online synchronous assessments for conducting a formal mid‐term exam, including synchronous quiz, synchronous practicum, synchronous essay and synchronous oral assessments. The designs were implemented and evaluated in a synchronous cyber classroom for an online credit course. This study identified the challenges and potential issues while conducting the online synchronous assessments, including (1) the extent of monitoring and cheating; (2) the lack of suitable software tools specifically for supporting online synchronous assessments; and (3) the need for a variety of online synchronous assessment methods for different subject matter. This paper concludes with some possible solutions, such as a short time limit for answering questions and a well analysed need of a software tool, to address all the issues.

Protein chip for the parallel quantification of high and low abundant biomarkers for sepsis

We present herein a protein chip for diagnosis of sepsis that combines both a sandwich and a binding inhibition format in order to quantify high (CRP) and low abundant proteins (cytokines, PCT, neopterin) in parallel. Using the combined assay format the lowest detectable concentrations for CRP, IL-6, IL-8, IL-10, TNFα, PCT, and neopterin are 3 mg/L, 15 ng/L, 26 ng/L, 65 ng/L, 40 ng/L, 78 ng/L, and 0.46 μg/L. Four different combined assay formats are tested, using separate or joint incubation steps of analytes and detection antibodies. Yet, low limit of detection (LOD) and short processing time are contradictory: while the combined assay performed in a multistep protocol is extremely sensitive (e.g., the LOD for IL-6 is 15 ng/L), but more time-consuming (4 h), the all-in-one protocol takes only 2.5 h, but suffers from lower sensitivity compared with the multistep protocol (e.g., the LOD for IL-6 is up to 40 times enhanced). Reproducibility is good in both cases (CV 5–20%).

Condensed phase molecular dynamics using interpolated potential energy surfaces with application to the resolvation process of coumarin 153

Interpolated potential energy surfaces (PESs) have been used for performing reliable molecular dynamics (MD) simulations of small molecular reactions. In this article, we extend this method to MD simulations in condensed phase and show that the same scheme can also be feasibly used when it is supplemented with additional terms for describing intermolecular interactions. We then apply the approach for studying the resolvation process of coumarin 153 in a number of polar solvents. We find that the interpolated surface actually reproduces experimentally found features much better than the conventional force field based potential especially in terms of both dynamics Stokes shift in the short time limit and solute vibrational decoherence. This shows that the solute vibrational effect is important to some degree along the resolvation and should be modeled properly for accurate description of the related dynamics. The stability issue of trajectories on the interpolated PESs is also discussed, in regard to the goal of reliably performing long time simulations. Operational limitations of the present scheme are also discussed.

Enterprise Multi–Project Selection Combination Restrained by Resources

Enterprises often develop more than one project at the same time, within relatively short time limit, and many elements involved , which puts a greate influence on the completion . In the present enterprise project management, there are phenomena that project relationship is chaotic, plans not implemented and resources competed . After introducing the difference between multi–project management and common project management, this paper analyses multi–project selection restrained by resources with genetic model, then provides a method of solving multi–project selection and combination, and finally proves the method has a greater practical significance with a case.

Generalized Langevin equation with a three parameter Mittag-Leffler noise

The relaxation functions for a given generalized Langevin equation in the presence of a three parameter Mittag-Leffler noise are studied analytically. The results are represented by three parameter Mittag-Leffler functions. Exact results for the velocity and displacement correlation functions of a diffusing particle are obtained by using the Laplace transform method. The asymptotic behavior of the particle in the short and long time limits are found by using the Tauberian theorems. It is shown that for large times the particle motion is subdiffusive for β−1<αδ<β, and superdiffusive for β<αδ. Many previously obtained results are recovered. Due to the many parameters contained in the noise term, the model considered in this work may be used to improve the description of data and to model anomalous diffusive processes in complex media.

Generating transition paths by Langevin bridges

We propose a novel stochastic method to generate paths conditioned to start in an initial state and end in a given final state during a certain time t(f). These paths are weighted with a probability given by the overdamped Langevin dynamics. We show that these paths can be exactly generated by a non-local stochastic differential equation. In the limit of short times, we show that this complicated non-solvable equation can be simplified into an approximate local stochastic differential equation. For longer times, the paths generated by this approximate equation do not satisfy the correct statistics, but this can be corrected by an adequate reweighting of the trajectories. In all cases, the paths are statistically independent and provide a representative sample of transition paths. The method is illustrated on the one-dimensional quartic oscillator.

Two-spin dephasing by electron-phonon interaction in semiconductor double quantum dots

We study electron-phonon interaction induced decoherence between two-electron singlet and triplet states in a semiconductor double quantum dot using a spin-boson model. We investigate the onset and time evolution of this dephasing, and study its dependence on quantum dot parameters such as dot size and double dot separations, as well as the host materials (GaAs and Si). At the short time limit, electron-phonon interaction only causes an incomplete initial Gaussian decay of the off-diagonal density matrix element in the singlet-triplet Hilbert space. A complete long-time exponential decay due to phonon relaxation would eventually dominate over two-spin decoherence. We analyze two-spin decoherence in both symmetric and biased double quantum dots, identifying their difference in electron-phonon coupling and the relevant consequences.

Excitonic coherence in a confined lattice: A simple model to highlight the relevance of perturbation theory

The exciton-phonon system in a confined environment is revisited within standard perturbation theory. Special attention is paid to describing the time evolution of the excitonic coherences at finite temperature. To proceed, the system involving an exciton dressed by a single phonon mode is considered. Owing to its simplicity, it is solved exactly so that the relevance of the perturbation theory is checked. Within the nonadiabatic weak-coupling limit, it is shown that several time scales govern the coherence dynamics. In the short-time limit, the coherences behave as if the exciton was insensitive to the phonon bath. Then, quantum decoherence takes place. Finally the coherences recur almost periodically at specific revival times. Coherence decay and revival strongly depend on the nature of the excitonic states. In particular, for odd lattice sizes, the coherence of the state exactly located at the band center survives over a very long-time scale. Therefore, confinement-induced decoherence softening favors high-fidelity quantum-state transfer and allows to encode the information on a quantum bit almost insensitive to quantum decoherence.

The flux-flux correlation function for anharmonic barriers

The flux-flux correlation function formalism is a standard and widely used approach for the computation of reaction rates. In this paper we introduce a method to compute the classical and quantum flux-flux correlation functions for anharmonic barriers essentially analytically through the use of the classical and quantum normal forms. In the quantum case we show that for a general f degree-of-freedom system having an index one saddle the quantum normal form reduces the computation of the flux-flux correlation function to that of an effective one-dimensional anharmonic barrier. The example of the computation of the quantum flux-flux correlation function for a fourth order anharmonic barrier is worked out in detail, and we present an analytical expression for the quantum mechanical microcanonical flux-flux correlation function. We then give a discussion of the short-time and harmonic limits.

Dynamical decoupling for a qubit in telegraphlike noises

Based on the stochastic theory developed by Kubo and Anderson, we present an exact result of the decoherence function of a qubit in telegraphlike noises under dynamical decoupling control. We prove that for telegraphlike noises, the decoherence can be suppressed at most to the third order of the time and the periodic Carr-Purcell-Merboom-Gill sequences are the most efficient scheme in protecting the qubit coherence in the short-time limit.

Evidence for short-time limit of martensite deaging in shape-memory alloys: Experiment and atomistic simulation

It is well known that martensite aging effects in shape memory alloys can be simply removed when the aged martensite experiences a reverse transformation to the parent phase followed by cooling back to the martensite state. This “deaging” process has been known to be very fast but it remains a question as to whether there exists a short-time limit for such a fast deaging process. In this letter, we report that there indeed exists a short-time limit for the deaging. We have studied the aging and deaging of a Au-49.5Cd shape memory alloy, and found that complete removal of the previous aging, as manifested by the recovery of martensite transition start temperature (Ms), occurs only after aging in the parent phase for more than 500 s. Shorter time holding/aging in the parent phase results in a higher Ms as compared with the fully deaged case. Therefore, there is a fast relaxation process during the deaging or parent phase aging process. Atomistic simulations suggest that the origin of the observed time-dependent deaging arises from the change in short-range configurations of point defects, being the same as that of the martensite aging. As a result, it is possible to unify the microscopic mechanism of aging in both martensite and parent phase; both are due to a symmetry-conforming short-range ordering tendency of point defects.

Approximate solutions to second order parabolic equations. I: Analytic estimates

We establish a new type of local asymptotic formula for the Green’s function Gt(x,y) of a uniformly parabolic linear operator ∂t−L with nonconstant coefficients using dilations and Taylor expansions at a point z=z(x,y) for a function z with bounded derivatives such that z(x,x)=x∊RN. Our method is based on dilation at z, Dyson, and Taylor series expansions. We use the Baker–Campbell–Hausdorff commutator formula to explicitly compute the terms in the Dyson series. Our procedure leads to an explicit, elementary, algorithmic construction of approximate solutions to parabolic equations that are accurate to arbitrarity prescribed order in the short-time limit. We establish mapping properties and precise error estimates in the exponentially weighed, Lp-type Sobolev spaces Was,p(RN) that appear in practice.

ON FLAVOR CONSERVATION IN WEAK INTERACTION DECAYS INVOLVING MIXED NEUTRINOS

In the context of quantum field theory (QFT), we compute the amplitudes of weak interaction processes such as W+ →e+ + νe and W+ →e+ + νμ by using different representations of flavor states for mixed neutrinos. Analyzing the short time limit of the above amplitudes, we find that the neutrino states defined in QFT as eigenstates of the flavor charges lead to results consistent with lepton charge conservation. On the contrary, the Pontecorvo flavor states produce a violation of lepton charge in the vertex, which is in contrast with what expected at tree level in the Standard Model.

Molecular dynamics with quantum fluctuations

A quantum dynamics approach, called Gaussian molecular dynamics, is introduced. As in the centroid molecular dynamics, the $N$-body quantum system is mapped to an $N$-body classical system with an effective Hamiltonian arising within the variational Gaussian wave-packet approximation. The approach is exact for the harmonic oscillator and for the high-temperature limit, accurate in the short-time limit and is computationally very efficient.

Asymptotic approaches to convective quasi-equilibrium

The physical principle of convective quasi-equilibrium proposed by Arakawa and Schubert states that the atmosphere is effectively adjusted to equilibrium by an active role of convective heating against large-scale forcing (physical convective quasi-equilibrium, or PCQ). A simple consequence of this principle is that the rate of change of the thermodynamic field (typically measured by the convective available potential energy (CAPE)) is much smaller than the rate of change of the large-scale forcing (diagnostic convective quasi-equilibrium, or DCQ). Such a diagnostic state is generally observed in the tropical atmosphere at the synoptic-scale, and this is often taken as a proof for the physical mechanisms behind Arakawa and Schubert's convective quasi-equilibrium: however, theoretically, there are several alternative physical mechanisms that are also able to establish this diagnostic state. The paper examines the approach of the tropical atmospheric system to DCQ with increasing time-scale in order to distinguish various alternatives to PCQ. The latter predicts that the system approaches DCQ exponentially with a time-scale characteristic of convection. However, the alternatives considered in the paper predict algebraic asymptotes to DCQ with increasing time-scale. First it is demonstrated that PCQ is not required to achieve DCQ by considering a linear primitive-equation system with arbitrary convective heating, in which the roles of convective heating and large-scale forcing are completely reversed; algebraic asymptotes are achieved. An even simpler analogue is to assume that the rate of generating CAPE is controlled by white-noise forcing. More generally, such an algebraic asymptote is obtained by any system with a power-law spectrum both for CAPE and large-scale forcing, although a restriction must be applied to ensure a decreasing asymptote with increasing time-scale. The approach to DCQ is examined for both the Maritime Continent Thunderstorm Experiment data and cloud-resolving model simulation data, and both indicate no tendency for exponential adjustments in the short time limit.

Role of spatial inhomogeneity in dissociation of trapped molecular condensates

We theoretically analyze dissociation of a harmonically trapped Bose-Einstein condensate of molecular dimers and examine how the spatial inhomogeneity of the molecular condensate affects the conversion dynamics and the atom-atom pair correlations in the short-time limit. Both fermionic and bosonic statistics of the constituent atoms are considered. Using the undepleted molecular-field approximation, we obtain explicit analytic results for the asymptotic behavior of the second-order correlation functions and for the relative number squeezing between the dissociated atoms in one, two, and three spatial dimensions. Comparison with the numerical results shows that the analytic approach employed here captures the main underlying physics and provides useful insights into the dynamics of dissociation for conversion efficiencies up to $10%$. The results show explicitly how the strength of atom-atom correlations and relative number squeezing degrade with the reduction of the size of the molecular condensate.

Dispersion and temperature statistics of inertial particles in isotropic turbulence

The dispersion and temperature distribution of inertial particles are important in many turbulent, multiphase flow problems. In order to understand these better, direct numerical simulations (DNSs) are performed for inertial particles in a fluid with a constant temperature gradient and whose motion is either statistically stationary or decaying, isotropic turbulence. It is found that, for long times, the dispersion of inertial particles is the greatest when the Stokes number, Stη=τp/τη, is of order 1, where τp and τη are, respectively, the particle response time and the flow Kolmogorov time scale. A similar result is found for the long time behavior of the time rate of change of the mean-square particle temperature fluctuations, d⟨Tp′2⟩/dt. To understand the DNS results better, an evolution equation for ⟨Tp′2⟩, along with the short and long time limits, is derived analytically from the thermal energy equation for inertial particles.