512 research outputs found
Linear Programming-Based Estimators in Simple Linear Regression
No full textIn this paper we introduce a linear programming estimator (LPE) for the slope parameter in a constrained linear regression model with a single regressor. The LPE is interesting because it can be superconsistent in the presence of an endogenous regressor and, hence, preferable to the ordinary least squares estimator (LSE). Two dierent cases are considered as we investigate the statistical properties of the LPE. In the rst case, the regressor is assumed to be xed in repeated samples. In the second, the regressor is stochastic and potentially endogenous. For both cases the strong consistency and exact nite-sample distribution of the LPE is established. Conditions under which the LPE is consistent in the presence of serially correlated, heteroskedastic errors are also given. Finally, we describe how the LPE can be extended to the case with multiple regressors and conjecture that the extended estimator is consistent under conditions analogous to the ones given herein. Finite-sample properties of the LPE and extended LPE in comparison to the LSE and instrumental variable estimator (IVE) are investigated in a simulation study. One advantage of the LPE is that it does not require an instrument.
Molecular Mechanisms of (R,R)ZX-5 on NO Synthesis and Its Anti-Angiogenic Effect
No full text(R,R)ZX-5 is a NO regulatory compound, which could significantly increase choroidal blood flow in New Zealand rabbit. The aim of this paper is to investigate the molecular mechanism of (R,R)ZX-5 promoting NO production. Besides this, we also investigated the antiangiogenic activity of (R,R)ZX-5. Analysis of Western blot showed that (R,R)ZX-5 up-regulated the expression of Akt, p-Akt (Thr473), eNOS and p-eNOS (Ser1177), down-regulated the expression of Cyclin D1 in human retinal endothelial cells and escalated the intracellular free Ca2+ concentration. Additionally, (R,R)ZX-5 inhibited the growth of blood vessels in the chick chorioallantoic membrane model. It is concluded that (R,R)ZX-5 promotes choroidal blood flow through PI3K/Akt-eNOS and Akt-Ca2+-eNOS pathways. Additionally, (R,R)ZX-5 can inhibit angiogenesis
Superdense Coding with GHZ and Quantum Key Distribution with W in the ZX-calculus
No full textQuantum entanglement is a key resource in many quantum protocols, such as quantum teleportation and quantum cryptography. Yet entanglement makes protocols presented in Dirac notation difficult to verify. This is why Coecke and Duncan have introduced a diagrammatic language for quantum protocols, called the ZX-calculus. This diagrammatic notation is both intuitive and formally rigorous. It is a simple, graphical, high level language that emphasises the composition of systems and naturally captures the essentials of quantum mechanics. In the author's MSc thesis it has been shown for over 25 quantum protocols that the ZX-calculus provides a relatively easy and more intuitive presentation. Moreover, the author embarked on the task to apply categorical quantum mechanics on quantum security; earlier works did not touch anything but Bennett and Brassard's quantum key distribution protocol, BB84. Superdense coding with the Greenberger-Horne-Zeilinger state and quantum key distribution with the W-state are presented in the ZX-calculus in this paper
On-top pair-correlation function in the homogeneous electron liquid
No full textThe ladder theory, in which the Bethe-Goldstone equation for the effective potential between two scattering particles plays a central role, is well known for its satisfactory description of the short-range correlations in the homogeneous electron liquid. By solving exactly the Bethe-Goldstone equation in the limit of large transfer momentum between two scattering particles, we obtain accurate results for the on-top pair-correlation function g(0), in both three dimensions and two dimensions. Furthermore, we prove, in general, that the ladder theory satisfies the cusp condition for the pair-correlation function g(r) at zero distance r=0.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000235009500047&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Physics, Condensed MatterSCI(E)8ARTICLE3null7
Improved fifth-order geometric aberration coeincients of electron lenses
No full textIn this paper, fifth-order geometric aberrations of round electron lenses have been restudied. Improved analytical formulae of the aberration coefficients were derived by the computer algebra software-Mathematica-and their correctness verified by cross-checking with numerical integration and differential algebraic techniques for a given electromagnetic lens.Physics, AppliedSCI(E)EI3ARTICLE5653-6593
Long-wavelength behavior of the dynamical spin-resolved local-field factor in a two-dimensional electron liquid
No full textThe high-frequency limits of the singular component A(omega) of the small wave-vector expansion of the longitudinal (L) and transverse (T) components of the spin-resolved exchange-correlation kernel tensor f(xc,sigmasigma)('L,T)(q,omega)=-v(q)G(sigmasigma)('L,T)(q,omega) in a two-dimensional isotropic electron liquid with arbitrary spin polarization are studied. Here G(sigmasigma)('L,T)(q,omega) is the spin-resolved local-field factor, v(q) is the Coulomb interaction in momentum space, and sigma denotes spin. Particularly, the real part of A(omega) is found to be logarithmically divergent at large omega. The large wave-vector structure of the corresponding spin-resolved static structure factor is also established.Physics, Condensed MatterSCI(E)1ARTICLE23null7
APFIM AND FEM STUDY OF MO-LA ALLOY WIRE
No full textPhysics, MultidisciplinarySCI(E)0ARTICLEC-6283-2864
Parameter Determination Using 3D FIB-SEM Images for Development of Effective Model of Shale Gas Flow in Nanoscale Pore Clusters
No full textA large amount of nano-pores exists in pore clusters in shale gas reservoirs. In addition to the multiple transport regimes that occur on the nanoscale the pore space is another major factor that significantly affects the shale gas recoverability. An investigation of the pore-scale shale gas flow is therefore important and the results can be used to develop an effective cluster-scale pore network model for the convenient examination of the process efficiency. Focused ion beam scanning electron microscope imaging which enables the acquisition of nanometre-resolution images that facilitate nano-pore identification was used in conjunction with a high-precision pore network extraction algorithm to generate the equivalent pore network for the simulation of Darcy and shale gas flows through the pores. The characteristic parameters of the pores and the gas transport features were determined and analysed to obtain a deeper understanding of shale gas flow through nanoscale pore clusters such as the importance of the throat flux-radius distribution and the variation of the tortuosity with pressure. The best parameter scheme for the proposed effective model of shale gas flow was selected out of three derived schemes based on the pore-scale prediction results. The model is applicable to pore-scale to cluster-scale shale gas flows and can be used to avoid the multiple-solution problems in the study of gas flows. It affords a foundation for further study to develop models for shale gas flows on larger scales
A STUDY OF MINIATURIZED ELECTROSTATIC OCTUPOLE DEFLECTORS
No full textIn this paper the computer simulation and the computational results of miniaturized electrostatic octupole deflectors have been presented. It has been shown that both axial and azimuthal fringing effects must be taken into account for such deflectors with small length-to-radius ratio. The axial fringing effects make deflection sensitivity higher, have no effects on deflection coma and chromatism coefficients, and change the behaviors of deflection field curvature, astigmatism, and distortion coefficients for the round-lens-type aberrations. The azimuthal fringing effects decrease deflection sensitivity but hardly affect any round-lens-type deflection aberration coefficients. For miniaturized electrostatic octupole deflectors the computational results also show that four-fold deflection coma, astigmatism, and distortion are all extremly small and can be completely neglected.Instruments & InstrumentationNuclear Science & TechnologyPhysics, Particles & FieldsSpectroscopySCI(E)
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