Precise Agreement Research Articles

ANALYTICAL SOLUTION OF SINGULAR FOURTH ORDER PARABOLIC PARTIAL DIFFERENTIAL EQUATIONS OF VARIABLE COEFFICIENTS BY USING HOMOTOPY PERTURBATION TRANSFORM METHOD

In this paper, we apply Homotopy perturbation transform method (HPTM) for solving singular fourth order parabolic partial dif- ferential equations with variable coefficients. This method is the combina- tion of the Laplace transform method and Homotopy perturbation method. The nonlinear terms can be easily handled by the use of He's polynomi- als. The aim of using the Laplace transform is to overcome the deficiency that is mainly caused by unsatisfied conditions in other semi-analytical methods such as Homotopy perturbation method (HPM), Variational it- eration method (VIM) and Adomain Decomposition method (ADM). The proposed scheme finds the solutions without any discretization or restric- tive assumptions and avoids the round-off errors. The comparison shows a precise agreement between the results and introduces this method as an applicable one which it needs fewer computations and is much easier and more convenient than others, so it can be widely used in engineering too.

The Brown Dwarf Eclipsing Binary 2M0535−05: A Case Study for Activity Effects on Physical Properties of Low-Mass Stars and Brown Dwarfs

2M0535−05 is a one-of-a-kind eclipsing binary (EB) comprising two brown dwarfs (BDs), and is an important benchmark for understanding the fundamental properties of BDs and low-mass stars. Because 2M0535−05 presents a peculiar reversal of temperatures with mass (the higher mass, magnetically active BD in the system is cooler than the lower mass companion BD), 2M0535−05 is particularly important as a case study for the effects of magnetic activity on the properties of low-mass objects. Using a large number of low-mass M-dwarfs and EBs in the field, we have developed empirical relations for determining the amount by which the temperatures and radii–and therefore the estimated masses–of low-mass stars and BDs are altered due to chromospheric activity. The relations link the amount by which an active object's temperature is suppressed, and its radius inflated, to the strength of its Hα emission. These relations are found to approximately preserve bolometric luminosity. Applying these relations to 2M0535−05 brings the activity-corrected radii and temperatures of 2M0535−05 into precise agreement with theoretical isochrones for inactive stars. The relations that we present are applicable to BDs and low-mass stars with masses below 0.8 M ⊙ and for which the activity, as measured by Hα, is in the range − 4.6 H α /L bol < −3.3. We discuss implications of this work for determinations of young cluster IMFs, and discuss competing ideas for the physical mechanism by which magnetic fields alter the temperatures and radii of low-mass stars.

Green Ionic Liquid Albumin Glassy Carbon Biosensor (ILAGC) for On-line Binding Studies of Human Serum Albumin with Retinol

A new biosensor composed of 1-butyl-3-methylimidazolium hexafluorophosphates (BMIMPF 6 )-human serum albumin (HSA) film coated on glassy carbon electrode (GCE) was produced. In the current work, the conjugation of ionic liquid (IL) with HSA improved the stability and binding affinity of protein onto GCE. A rapid and reliable voltammetric method for the on-line protein binding studies of retinol with HSA was developed by hyphenating ionic liquid albumin glassy carbon (ILAGC) biosensor with differential pulse anodic stripping voltammetry under physiological conditions. Detection limit and quantitation limit of 4.5 and 15.0 nmol L -1 were achieved, respectively. This gave us the opportunity to study the high binding constant between retinol and HSA by their detection in nanomolars. The electrochemical behavior of retinol onto ILAGC biosensor was monitored by cyclic voltammetry. The surface coverage of retinol on the proposed biosensor was calculated by double potential-step chronocoulometry. The binding constant of retinol with HSA was estimated to be 1.30×105 L mol-1 giving acceptable precision (SD ≤ 0.02) and good agreement with literature values. The proposed electrochemical biosensor opened a new venue for cheap, green and rapid on-line binding studies of small molecules with protein. As well, our proposed method could use to study either high or low binding affinities.

Correlators of Wilson loops and local operators from multi-matrix models and strings in AdS

We study correlation functions of Wilson loops and local operators in a sub-sector of $ \mathcal{N}=4 $ SYM which preserves two supercharges. Localization arguments allow to map the problem to a calculation in bosonic two-dimensional Yang-Mills theory. In turn, this can be reduced to computing correlators in certain Gaussian multi-matrix models. We focus on the correlation function of a Wilson loop and two local operators, and solve the corresponding three-matrix model exactly in the planar limit. We compare the strong coupling behavior to string theory in AdS 5 × S 5, finding precise agreement. We pay particular attention to the case in which the local operators have large R-charge $ J\sim \sqrt{\lambda } $ at strong coupling.

Discretization of Multidimensional Mathematical Equations of Dam Break Phenomena Using a Novel Approach of Finite Volume Method

This paper was concerned to simulate both wet and dry bed dam break problems. A high-resolution finite volume method (FVM) was employed to solve the one-dimensional (1D) and two-dimensional (2D) shallow water equations (SWEs) using an unstructured Voronoi mesh grid. In this attempt, the robust local Lax-Friedrichs (LLxF) scheme was used for the calculating of the numerical flux at cells interfaces. The model named V-Break was run under the asymmetry partial and circular dam break conditions and then verified by comparing the model outputs with the documented results. Due to a precise agreement between those output and documented results, the V-Break could be considered as a reliable method for dealing with shallow water (SW) and shock problems, especially those having discontinuities. In addition, statistical observations indicated a good conformity between the V-Break and analytical results clearly.

Kinetics of Low-Pressure, Low-Temperature Graphene Growth: Toward Single-Layer, Single-Crystalline Structure

Graphene grown on metal catalysts with low carbon solubility is a highly competitive alternative to exfoliated and other forms of graphene, yet a single-layer, single-crystal structure remains a challenge because of the large number of randomly oriented nuclei that form grain boundaries when stitched together. A kinetic model of graphene nucleation and growth is developed to elucidate the effective controls of the graphene island density and surface coverage from the onset of nucleation to the full monolayer formation in low-pressure, low-temperature CVD. The model unprecedentedly involves the complete cycle of the elementary gas-phase and surface processes and shows a precise quantitative agreement with the recent low-energy electron diffraction measurements and also explains numerous parameter trends from a host of experimental reports. These agreements are demonstrated for a broad pressure range as well as different combinations of precursor gases and supporting catalysts. The critical role of hydrogen in controlling the graphene nucleation and monolayer formation is revealed and quantified. The model is generic and can be extended to even broader ranges of catalysts and precursor gases/pressures to enable the as yet elusive effective control of the crystalline structure and number of layers of graphene using the minimum amounts of matter and energy.

A new non-overlapping block processing technique for realizing linear phase two-pass recursive digital filters

A technique is presented to realize recursive digital filters with a linear phase and arbitrary magnitude characteristics. It is based on a well-known non-causal two-pass forward/backward filtering; where, a non-overlapping segmentwise processing is involved for a real-time implementation. Initial conditions of the backward pass are calculated recursively instead of a direct computation in the previous Arias-de-Reyna and [email protected]?s non-overlapping method. Additionally, a single first in, first out memory (FIFO) is introduced to organize samples into a data queue structure, and it allows filtering in real-time sample-by-sample. These improvements over the prior non-overlapping method can reduce delays and data storage capacities, and get similar computational complexity and phase linearity precision in passband. We show through the proposed non-overlapping technique that the forward/backward scheme can be a good alternative and competitive over the Powell and [email protected]?s backward/forward realization. We get better data storage capacities and phase linearity precision in passband, with approximately the same delays. Simulation of group delay precision in agreement with our contributions is illustrated.

AN EMPIRICAL CORRECTION FOR ACTIVITY EFFECTS ON THE TEMPERATURES, RADII, AND ESTIMATED MASSES OF LOW-MASS STARS AND BROWN DWARFS

We present empirical relations for determining the amount by which the effective temperatures and radii -- and therefore the estimated masses -- of low-mass stars and brown dwarfs are altered due to chromospheric activity. We base our relations on a large set of low-mass stars in the field with Halpha activity measurements, and on a set of low-mass eclipsing binaries with X-ray activity measurements from which we indirectly infer the Halpha activity. Both samples yield consistent relations linking the amount by which an active object's temperature is suppressed, and its radius inflated, to the strength of its Halpha emission. These relations are found to approximately preserve bolometric luminosity. We apply these relations to the peculiar brown-dwarf eclipsing binary 2M0535-05, in which the active, higher-mass brown dwarf has a cooler temperature than its inactive, lower-mass companion. The relations correctly reproduce the observed temperatures and radii of 2M0535-05 after accounting for the Halpha emission; 2M0535-05 would be in precise agreement with theoretical isochrones were it inactive. The relations that we present are applicable to brown dwarfs and low-mass stars with masses below 0.8 Msun and for which the activity, as measured by the fractional Halpha luminosity, is in the range -4.6 < log LHa/Lbol < -3.3. We expect these relations to be most useful for correcting radius and mass estimates of low-mass stars and brown dwarfs over their active lifetimes (few Gyr) and when the ages or distances (and therefore luminosities) are unknown. We also discuss the implications of this work for improved determinations of young cluster initial mass functions.

Lung, Liver and Lymph Node Metastases in Follow-Up MSCT: Comprehensive Volumetric Assessment of Lesion Size Changes

To investigate measurement accuracy in terms of precision and inter-rater variability in the simultaneous volumetric assessment of lung, liver and lymph node metastasis size change over time in comparison to RECIST 1.1. Three independent readers evaluated multislice CT data from clinical follow-up studies (chest/abdomen) in 50 patients with metastases. A total of 117 lung, 77 liver and 97 lymph node metastases were assessed manually (RECIST 1.1) and by volumetry with semi-automated software. The quality of segmentation and need for manual adjustments were recorded. Volumes were converted to effective diameters to allow comparison to RECIST. For statistical assessment of precision and interobserver agreement, the Wilcoxon-signed rank test and Bland-Altman plots were utilized. The quality of segmentation after manual correction was acceptable to excellent in 95 % of lesions and manual corrections were applied in 21 - 36 % of all lesions, most predominantly in lymph nodes. Mean precision was 2.6 - 6.3 % (manual) with 0.2 - 1.5 % (effective) relative measurement deviation (p <.001). Inter-reader median variation coefficients ranged from 9.4 - 12.8 % (manual) and 2.9 - 8.2 % (volumetric) for different lesion types (p < .001). The limits of agreement were ± 9.8 to ± 11.2 % for volumetric assessment. Superior precision and inter-rater variability of volumetric over manual measurement of lesion change over time was demonstrated in a whole body setting.

The gravity dual of supersymmetric gauge theories on a squashed three-sphere

We present the gravity dual to a class of three-dimensional N=2 supersymmetric gauge theories on a U(1)×U(1)-invariant squashed three-sphere, with a non-trivial background gauge field. This is described by a supersymmetric solution of four-dimensional N=2 gauged supergravity with a non-trivial instanton for the graviphoton field. The particular gauge theory in turn determines the lift to a solution of eleven-dimensional supergravity. We compute the partition function for a class of Chern–Simons quiver gauge theories on both sides of the duality, in the large N limit, finding precise agreement for the functional dependence on the squashing parameter. This constitutes an exact check of the gauge/gravity correspondence in a non-conformally invariant setting.

5d quivers and their AdS 6 duals

We consider an infinite class of 5d supersymmetric gauge theories involving products of symplectic and unitary groups that arise from D4-branes at orbifold singularities in Type I' string theory. The theories are argued to be dual to warped AdS(6)x S4/Zn backgrounds in massive Type IIA supergravity. In particular, this demonstrates the existence of supersymmetric 5d fixed points of quiver type. We analyze the spectrum of gauge fields and charged states in the supergravity dual, and find a precise agreement with the symmetries and charged operators in the quiver theories. We also comment on other brane objects in the supergravity dual and their interpretation in the field theories.

Critical points of the O(n) loop model on the martini and the 3-12 lattices

We derive the critical line of the O(n) loop model on the martini lattice as a function of the loop weight n basing on the critical points on the honeycomb lattice conjectured by Nienhuis [Phys. Rev. Lett. 49, 1062 (1982)]. In the limit n→0 we prove the connective constant μ=1.7505645579⋯ of self-avoiding walks on the martini lattice. A finite-size scaling analysis based on transfer matrix calculations is also performed. The numerical results coincide with the theoretical predictions with a very high accuracy. Using similar numerical methods, we also study the O(n) loop model on the 3-12 lattice. We obtain similarly precise agreement with the critical points given by Batchelor [J. Stat. Phys. 92, 1203 (1998)].

The cusp anomalous dimension at three loops and beyond

We derive an analytic formula at three loops for the cusp anomalous dimension Gamma_cusp(phi) in N=4 super Yang-Mills. This is done by exploiting the relation of the latter to the Regge limit of massive amplitudes. We comment on the corresponding three loops quark anti-quark potential. Our result also determines a considerable part of the three-loop cusp anomalous dimension in QCD. Finally, we consider a limit in which only ladder diagrams contribute to physical observables. In that limit, a precise agreement with strong coupling is observed.

Adaptive Green-Kubo estimates of transport coefficients from molecular dynamics based on robust error analysis

We present a rigorous Green-Kubo methodology for calculating transport coefficients based on on-the-fly estimates of: (a) statistical stationarity of the relevant process, and (b) error in the resulting coefficient. The methodology uses time samples efficiently across an ensemble of parallel replicas to yield accurate estimates, which is particularly useful for estimating the thermal conductivity of semi-conductors near their Debye temperatures where the characteristic decay times of the heat flux correlation functions are large. Employing and extending the error analysis of Zwanzig and Ailawadi [Phys. Rev. 182, 280 (1969)] and Frenkel [in Proceedings of the International School of Physics "Enrico Fermi", Course LXXV (North-Holland Publishing Company, Amsterdam, 1980)] to the integral of correlation, we are able to provide tight theoretical bounds for the error in the estimate of the transport coefficient. To demonstrate the performance of the method, four test cases of increasing computational cost and complexity are presented: the viscosity of Ar and water, and the thermal conductivity of Si and GaN. In addition to producing accurate estimates of the transport coefficients for these materials, this work demonstrates precise agreement of the computed variances in the estimates of the correlation and the transport coefficient with the extended theory based on the assumption that fluctuations follow a Gaussian process. The proposed algorithm in conjunction with the extended theory enables the calculation of transport coefficients with the Green-Kubo method accurately and efficiently.

CFT duals of black rings with higher derivative terms

We study possible CFT duals of supersymmetric five dimensional black rings in the presence of supersymmetric higher derivative corrections to the supergravity action. A Virasoro algebra associated to an asymptotic symmetry group of solutions is defined by using the Kerr/CFT approach. We find the central charge and compute the microscopic entropy which is in precise agreement with the macroscopic entropy. Although apparently related to a different aspect of the near-horizon geometry and a different Virasoro algebra, we find that the c-extremization method leads to the same central charge and microscopic entropy computed in the Kerr/CFT approach. The relationship between these two point of view is clarified by relating the geometry to a self-dual orbifold of AdS3.

Equilibrium-reduced density matrix formulation: Influence of noise, disorder, and temperature on localization in excitonic systems

An exact method to compute the entire equilibrium reduced density matrix for systems characterized by a system-bath Hamiltonian is presented. The approach is based upon a stochastic unraveling of the influence functional that appears in the imaginary time path integral formalism of quantum statistical mechanics. This method is then applied to study the effects of thermal noise, static disorder, and temperature on the coherence length in excitonic systems. As representative examples of biased and unbiased systems, attention is focused on the well-characterized light harvesting complexes of FMO and LH2, respectively. Due to the bias, FMO is completely localized in the site basis at low temperatures, whereas LH2 is completely delocalized. In the latter, the presence of static disorder leads to a plateau in the coherence length at low temperature that becomes increasingly pronounced with increasing strength of the disorder. The introduction of noise, however, precludes this effect. In biased systems, it is shown that the environment may increase the coherence length, but only decrease that of unbiased systems. Finally it is emphasized that for typical values of the environmental parameters in light harvesting systems, the system and bath are entangled at equilibrium in the single excitation manifold. That is, the density matrix cannot be described as a product state as is often assumed, even at room temperature. The reduced density matrix of LH2 is shown to be in precise agreement with the steady state limit of previous exact quantum dynamics calculations.

Computational polarization imaging from a single speckle image

We experimentally demonstrate that imaging of the degree of polarization (DOP) can be achieved from a single intensity image acquired under coherent illumination. This computational technique is based on the analysis of the speckle characteristics in a statistically homogeneous neighborhood of the pixel. Over a variety of samples obtained experimentally, we show that a simple calibration step allows this method to quickly and simply provide correct estimated values of the DOP, with precision in agreement with theoretical predictions. It is shown that unlike linear polarimetric contrast imaging, this method remains valid on birefringent samples.

Actuation and tracking of a single magnetic particle on a chip

We present the defined actuation of a single magnetic particle on a crossbar array chip. Two orthogonal layers of parallel microwires are used to generate highly localized magnetic field gradients for particle trapping and movement. We introduce an analytical model to simulate the actuation of the particle, which is in precise agreement with the experimentally observed trajectory. The single-particle approach allows us to resolve subtle features of the induced magnetic field distribution. We demonstrate that the actuation strongly depends on the applied current sequence and introduce switching patterns for reliable control of an individual particle.

Nonequilibrium Molecular Dynamics of Trp Zwitterion in Water: Picosecond Fluorescence Measurements Versus Computer Simulations

This is an experimental test of MD simulations on the picosecond timescale. Tryptophan zwitterion in TIP3P water at 278°K was simulated using CHARMM22 forcefield with the excited-state Trp atomic charges from [Toptygin et al., J. Phys. Chem. B 2010, 114, 11323]. Six stable excited-state rotamers of Trp sidechain were found with the population density peaks near (χ1,χ2) = (67°,80°), (−170°,57°), (−65°,115°), (65°,-85°), (−165°,-112°), (−65°,-80°). Curved boundaries between the rotamers on the (χ1,χ2) map were drawn along the troughs of the population density. Population density distribution within the boundaries of one rotamer reaches equilibrium in less than 20ps; equilibration between different rotamers takes much longer. At t>20ps rotamer populations can be described by a system of six first-order homogeneous linear differential equations. The solution is a sum of six terms Vmnexp(-t/τn). Population decay of each rotamer is not monoexponential and τn is not a lifetime. The same set of τn applies to all rotamers, but a different set of Vmn corresponds to each rotamer. The rotamers have slightly different fluorescence emission spectra, therefore fluorescence intensity is a sum of six terms αn(ν)exp(-t/τn), where αn vary with the photon energy hν. We have determined τn and αn(ν) in the global analysis of spectrally- and time-resolved fluorescence data (time resolution 65ps FWHM). Only four exponential terms could be resolved from the experimental data in H2O at 5°C (τ1 = 4780ps, τ2 = 2500ps, τ3 = 867ps, τ4 = 411ps); according to MD simulations the fifth term (τ5 = 241ps) has a very small amplitude, and the sixth (τ6 = 22ps) is faster than the time resolution. For a precise agreement between the experimental and simulated values of τn it is necessary to lower all potential barriers between rotamers by 0.178kcal/mol. This shows that fluorescence spectroscopy can be used to fine-tune torsional parameters.

Interpolating Thin-Shell and Sharp Large-Deviation Estimates for Lsotropic Log-Concave Measures

Given an isotropic random vector X with log-concave density in Euclidean space \({\mathbb{R}^n}\) , we study the concentration properties of |X| on all scales, both above and below its expectation. We show in particular that $$\begin{array}{l} \mathbb{P}\left ( \left | |X| - \sqrt{n} \right | \geq t\sqrt{n} \right ) \leq C \, {\rm exp} \left ( -cn^{1/2} {\rm min}(t^{3}, t) \right) \; \forall t \geq 0, \end{array}$$ for some universal constants c, C > 0. This improves the best known deviation results on the thin-shell and mesoscopic scales due to Fleury and Klartag, respectively, and recovers the sharp large-deviation estimate of Paouris. Another new feature of our estimate is that it improves when X is \({\psi_{\alpha}\, (\alpha \in(1, 2])}\) , in precise agreement with Paouris’ estimates. The upper bound on the thin-shell width \({\sqrt{\mathbb{V}{\rm ar}(|X|)}}\) we obtain is of the order of n1/3, and improves down to n1/4 when X is \({\psi_{2}}\) . Our estimates thus continuously interpolate between a new best known thin-shell estimate and the sharp large-deviation estimate of Paouris. As a consequence, a new best known bound on the Cheeger isoperimetric constant appearing in a conjecture of Kannan.Lovasz-Simonovits is deduced.