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The determination of the fall velocity of non-cohesive particles (sand) was measured experimentally by using a technique of filming with a commercial camera. The diameters of the sediment ranged from 0.075 mm to 2 mm, the experimental values were compared with the ones calculated by empirical equations, four equations only consider the diameter to calculate the falling speed, the fifth equation considers diameter and form factor (cfs), and sixth equation considers diameter, form factor, and roundness (P). The results showed that the filming technique allows measuring the falling speed adequately and a sediment diameter range from 0.075 mm to 1.2 mm, the equation that includes the form factors and roundness had one of the best performances. [ABSTRACT FROM AUTHOR]

We investigated the generation dependent shape and internal structure of star-burst dendrimers under good solvent conditions using small angle x-ray scattering and molecular modeling. Measurements have been performed on poly(amidoamine) dendrimers with generations ranging from g=0 up to g=8 at low concentrations in methanol. We described the static form factor P(q) by a model taking into account the compact, globular shape as well as the loose, polymeric character of dendrimers. Monomer distributions within dendrimers are of special interest for potential applications and have been characterized by the pair correlation function γ(r), as well as by the monomer and end-group density profile, ρ(r) and ρe(r), respectively. Monomer density profiles and γ(r) can be derived from P(q) by modeling and via a model independent approach using the inverse Fourier transformation algorithm first introduced by Glatter. Experimental results are compared with computer simulations performed for single dendrimers of various generations using the cooperative motion algorithm. The simulation gives direct access to γ(r) and ρ(r), allows an independent determination of P(q), and yields in addition to the scattering experiment information about the distribution of the end groups. Excellent qualitative agreement between experiment and simulation has been found. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Off-lattice Monte Carlo simulations employing the PIVOT algorithm are used to generate ideal and excluded volume linear polymers in two dimensions. The form factor at small and large wave vectors is calculated from the resulting configurations and compared to the exact equation for ideal chains and to both scaling and renormalization group predictions for excluded volume chains. It is found that using the des Cloizeaux form for the distance distribution function in an analytic calculation of the form factor leads to close agreement with the Monte Carlo data and that simple expressions for both the small and large wave vector expansions reproduce the essential features of the form factor. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this paper we investigate the form factors of paths for a class of non Gaussian processes. These processes are characterized in terms of the Mittag-Leffler function. In particular, we obtain a closed analytic form for the form factors, the Debye function, and can study their asymptotic decay. [ABSTRACT FROM AUTHOR]

Abstract We extend previous calculations of the non-local form factors of semiclassical gravity in 4 D to include the Einstein–Hilbert term. The quantized fields are massive scalar, fermion and vector fields. The non-local form factor in this case can be seen as the sum of a power series of total derivatives, but it enables us to derive the beta function of Newton's constant and formally evaluate the decoupling law in the new sector, which turns out to be the standard quadratic one. [ABSTRACT FROM AUTHOR]

Abstract It has been observed in multiple lattice determinations of isovector axial and pseudoscalar nucleon form factors, that, despite the fact that the partial conservation of the axialvector current is fulfilled on the level of correlation functions, the corresponding relation for form factors (sometimes called the generalized Goldberger–Treiman relation in the literature) is broken rather badly. In this work we trace this difference back to excited state contributions and propose a new projection method that resolves this problem. We demonstrate the efficacy of this method by computing the axial and pseudoscalar form factors as well as related quantities on ensembles with two flavors of improved Wilson fermions using pion masses down to 150 MeV. To this end, we perform the z -expansion with analytically enforced asymptotic behaviour and extrapolate to the physical point. [ABSTRACT FROM AUTHOR]

Abstract The electromagnetic form factors of a composite vector particle within the light-front formulation of the Mandelstam formula is investigated. In order to extract the form factors from the matrix elements of the plus component of the current in the Drell–Yan frame, where the momentum transfer is chosen such that q + = q 0 + q 3 = 0 , one has in principle the freedom to choose between different linear combinations of matrix elements of the current operator. The different prescriptions to calculate the electromagnetic form factors, G 0 , G 1 and G 2 , i.e.; charge form factor, magnetic and quadrupole respectively. If the covariance is respected, all prescriptions give the same results; misfortune, is not the situation; the light-front approach produce different results, which depend of the prescriptions as utilized to extract the electromagnetic form factors in the case of the spin-1 particles. The main differences of the prescriptions appear because of the light-front matrix elements of the electromagnetic current are contaminated by the zero-modes contributions to the same with the plus component of the matrix elements of the electromagnetic current. However, the Inna Grach prescription is immune to the zero-modes contributions to the electromagnetic current, then the electromagnetic form factors extracted with that prescriptions do not have zero-modes contribution and give the same result compared with the instant form quantum field theory. Another's prescriptions with the light-front approach are contaminated by the zero-modes contributions to the matrix elements of the electromagnetic current with the plus component of the current. With some relations between the electromagnetic matrix elements of the electromagnetic current J j i + , as demonstrated analytical here, it was possible to calculate the electromagnetic form factors for spin-1 particles without zero-modes or non-valence contributions. [ABSTRACT FROM AUTHOR]

Abstract We present a theoretical parametrization of the nucleon electromagnetic form factors (FFs) based on a combination of chiral effective field theory and dispersion analysis. The isovector spectral functions on the two-pion cut are computed using elastic unitarity, chiral pion–nucleon amplitudes, and timelike pion FF data. Higher-mass isovector and isoscalar t -channel states are described by effective poles, whose strength is fixed by sum rules (charges, radii). Excellent agreement with the spacelike proton and neutron FF data is achieved up to Q 2 ∼ 1 GeV2. Our parametrization provides proper analyticity and theoretical uncertainty estimates and can be used for low- Q 2 FF studies and proton radius extraction. [ABSTRACT FROM AUTHOR]

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The design and synthesis of a novel nuclear factor erythroid 2- related factor 2 (Nrf2) enhancer is reported. Using a structure-based virtual screening approach, several commercially available compounds were identified as having high probability to interact with the Nrf2-binding pocket in the Kelch-like ECH-associated protein 1 (Keap1). Keap1 is an adaptor protein that recruits Nrf2 to a cullin-3-dependent ubiquitin ligase complex. The identified compounds were tested against rat pheochromocytoma PC-12 cells for their cytoprotective activity, and one compound (SKT359126) demonstrated an Nrf2-mediated cell-protective effect. Based on the structure of SKT359126, 23 novel derivatives were synthesized and evaluated. Of the screened derivatives, 1-{4-[(3,4-dihydroxybenzylidene)amino]- phenyl}-5-oxopyrrolidine-3-carboxylic acid demonstrated better activity than the parent molecules in activating the Nrf2 transduction pathway in a dose- and time-dependent manner. This compound represents a promising starting point for the development of therapeutics for the treatment of oxidative-stress-related diseases. [ABSTRACT FROM AUTHOR]

We give an overview of our recent efforts to extract electromagnetic transition form factors for N* and Δ* baryon resonances through a global analysis of the single-pion electroproductions off the proton within the ANL-Osaka dynamical coupled-channels approach. Preliminary results for the extracted form factors associated with Δ(1232)3/2+ and the Roper resonance are presented, with emphasis on the complex-valued nature of the transition form factors defined by poles. [ABSTRACT FROM AUTHOR]

In matrix algebras, we introduce a class of linear maps that are irreducibly covariant with respect to the finite group generated by the Weyl operators. In particular, we analyze the irreducibly covariant quantum channels, that is, the completely positive and trace-preserving linear maps. Interestingly, imposing additional symmetries leads to the so-called generalized Pauli channels, which were recently considered in the context of the non-Markovian quantum evolution. Finally, we provide examples of irreducibly covariant positive but not necessarily completely positive maps. [ABSTRACT FROM AUTHOR]

In this study, a prediction method of the form factor for a full-scale ship is suggested to minimize the power prediction error from a small model ship. Numerical simulations were carried out at various Reynolds numbers from a small model to a full-scale ship. The variation of the form factors was investigated from the results of the numerical simulation according to the Reynolds numbers. In addition, the results from the numerical simulations and experimental data of the geosim models were utilized to drive the correlation line and predict the form factor of a full-scale ship. The correlation line was applied to predict the effective power and the delivered power of a full-scale ship. As a result, the developed prediction method confirmed the possibility of predicting the power reliably from experiments using a small model. [ABSTRACT FROM AUTHOR]

By using the AdS/CFT correspondence, we investigate various form factors between nucleons and mesons in a nuclear medium. In order to describe a nuclear medium holographically, we take into account the thermal charged AdS geometry with an appropriate IR cutoff. After introducing an anomalous dimension as a free parameter, we investigate how the nucleon's mass is affected by the change of the anomalous dimension. Moreover, we study how the form factors of nucleons rely on the properties of the nuclear medium. We show that in a nuclear medium with different numbers of proton and neutron, the degenerated nucleon form factor in the vacuum is split into four different values depending on the isospin charges of nucleon and meson. [ABSTRACT FROM AUTHOR]

In this study, the contribution of the u and d quark electromagnetic form factors for the proton and neutron has been studied as well as regaining the nucleon form factors by considering the modified Gaussian ansatz based on GPDs and using an appropriate PDFs in which we consider the minimum parameters in comparison with other proposed parameterizations in calculating form factors. Our obtained results for u and q quark show suitable agreement with experimental data in the range 0 GeV 2 < − t < 4.5 GeV 2 of momentum transfer. Additionally, we calculate the N → Δ magnetic transition form factor, the gravitational form factor, and transverse density for quarks of nucleon. Finally, we compare our result with other previous works by considering the advantage of our used parameterization for u and d quark, proton, and neutron. [ABSTRACT FROM AUTHOR]

The four-loop Sudakov form factor in maximal super Yang-Mills theory is analysed in detail. It is shown explicitly how to construct a basis of integrals that have a uniformly transcendental expansion in the dimensional regularisation parameter, further elucidating the number-theoretic properties of Feynman integrals. The physical form factor is expressed in this basis for arbitrary colour factor. In the nonplanar sector the required integrals are integrated numerically using a mix of sector-decomposition and Mellin-Barnes representation methods. Both the cusp as well as the collinear anomalous dimension are computed. The results show explicitly the violation of quadratic Casimir scaling at the four-loop order. A thorough analysis concerning the reliability of reported numerical uncertainties is carried out. [ABSTRACT FROM AUTHOR]

We present a fully integrated energy reservoir unit using a counter flow method for peak power delivery in space-constrained sensor systems. Recent advances in circuits have enabled significant reduction in the size of wireless systems such as implantable biomedical devices. As a consequence, the batteries integrated in these systems have also shrunk, resulting in high internal resistances ( \sim 10 ~\textk\Omega ). However, the peak current requirement of power-hungry components such as radios remains in the milliwatt range and hence cannot directly be supplied from the battery. Therefore, an energy reservoir with high output power but small size is required. We present an efficient energy reservoir that dynamically reconfigures a storage capacitor array using a so-called counter flow approach. By creating a voltage gradient on capacitor arrays and moving the capacitors along the slope of the gradient, the supply voltage can be maintained while the energy stored in the reservoir is delivered efficiently to the load. The counter flow energy reservoir delivers 65% of stored energy before recharging is needed which allows up to a 12 \times reduction in overall capacitor size compared with our implementation of the previous method. The design supplies up to 13.6-mW output power for 1 ~\mu \text{s} . We demonstrate the proposed concept with a pulsed radio, showing an 11.5 \times$ increase in pulse length compared with the previous method. [ABSTRACT FROM AUTHOR]

We use the QCD sum rules for the three point correlation functions to compute the strong coupling constants of the meson vertices η c D ⁎ D and η c D s ⁎ D s . We consider perturbative and non-perturbative contributions, working up to dimension five on the OPE. The vertices were studied considering that each one of its three mesons are off-shell alternately. The vertex coupling constant is evaluated through the extrapolation of the three different form factors. The results obtained for the coupling constants are g η c D ⁎ D = 5.23 − 1.38 + 1.80 and g η c D s ⁎ D s = 5.55 − 1.55 + 1.29 . [ABSTRACT FROM AUTHOR]

We discuss the role of meson exchange mechanisms in γ γ → γ γ scattering. Several pseudoscalar ( π 0 , η , η ′ ( 958 ) , η c ( 1 S ) , η c ( 2 S ) ), scalar ( f 0 ( 500 ) , f 0 ( 980 ) , a 0 ( 980 ) , f 0 ( 1370 ) , χ c 0 ( 1 P ) ) and tensor ( f 2 ( 1270 ) , a 2 ( 1320 ) , f 2 ′ ( 1525 ) , f 2 ( 1565 ) , a 2 ( 1700 ) ) mesons are taken into account. We consider not only s -channel but also for the first time t - and u -channel meson exchange amplitudes corrected for off-shell effects including vertex form factors. We find that, depending on not well known vertex form factors, the meson exchange amplitudes interfere among themselves and could interfere with fermion-box amplitudes and modify the resulting cross sections. The meson contributions are shown as a function of collision energy as well as angular distributions are presented. Interesting interference effects separately for light pseudoscalar, scalar and tensor meson groups are discussed. The meson exchange contributions may be potentially important in the context of a measurement performed recently in ultraperipheral collisions of heavy ions by the ATLAS collaboration. The light-by-light interactions could be studied in future in electron–positron collisions by the Belle II at SuperKEKB accelerator. [ABSTRACT FROM AUTHOR]

A broad program measuring parity-violation in electron-nuclear scattering has now provided a large set of precision data on the weak-neutral-current form-factors of the proton. Under comparison with well-measured electromagnetic nucleon form-factors, these measurements reveal the role of the strange quark sea on the low-energy interactions of the proton through the strange-quark-flavor vector form-factors. This review will describe the experimental program and the implications of the global data for the strange-quark vector form-factors. We present here a new fit to the world data. [ABSTRACT FROM AUTHOR]

We review recent theoretical and experimental progress on the role of two-photon exchange (TPE) in electron–proton scattering at low to moderate momentum transfers. We make a detailed comparison and analysis of the results of competing experiments on the ratio of e + p to e − p elastic scattering cross sections, and of the theoretical calculations describing them. A summary of the current experimental situation is provided, along with an outlook for future experiments. [ABSTRACT FROM AUTHOR]

We solve renormalization group equations that govern infrared divergences of massless and massive form factors. By comparing to recent results for planar massive three-loop and massless four-loop form factors in QCD, we give predictions for the high-energy limit of massive form factors at the four- and for the massless form factor at five-loop order. Furthermore, we discuss the relation which connects infrared divergences regularized dimensionally and via a small quark mass and extend results present in the literature to higher order. [ABSTRACT FROM AUTHOR]

We compute perturbative QCD corrections to B → D form factors at leading power in Λ/ m , at large hadronic recoil, from the light-cone sum rules (LCSR) with B-meson distribution amplitudes in HQET. QCD factorization for the vacuum-to- B-meson correlation function with an interpolating current for the D-meson is demonstrated explicitly at one loop with the power counting scheme $$ {m}_c\sim \mathcal{O}\left(\sqrt{\Lambda {m}_b}\right) $$ . The jet functions encoding information of the hard-collinear dynamics in the above-mentioned correlation function are complicated by the appearance of an additional hard-collinear scale m , compared to the counterparts entering the factorization formula of the vacuum-to- B-meson correction function for the construction of B → π from factors. Inspecting the next-to-leading-logarithmic sum rules for the form factors of B → Dℓν indicates that perturbative corrections to the hard-collinear functions are more profound than that for the hard functions, with the default theory inputs, in the physical kinematic region. We further compute the subleading power correction induced by the three-particle quark-gluon distribution amplitudes of the B-meson at tree level employing the background gluon field approach. The LCSR predictions for the semileptonic B → Dℓν form factors are then extrapolated to the entire kinematic region with the z-series parametrization. Phenomenological implications of our determinations for the form factors f ( q ) are explored by investigating the (differential) branching fractions and the R( D) ratio of B → Dℓν and by determining the CKM matrix element |V | from the total decay rate of B → Dμν . [ABSTRACT FROM AUTHOR]

Calculation results are presented for the form factor of a flat ring in a linear formulation of the theory of elasticity. The form factor accounts for the influence of the sample dimensions and Poisson's ratio on the modulus of elasticity being measured. The two-dimensional problem of elastic deformation of a ring with boundary conditions specified for its entire surface was solved. Six flat rings of various sizes were made and their modulus of elasticity was measured to validate the results of calculations. The dispersion of values of Young's modulus, corrected by the calculated form factor, did not exceed 2.5%, which corresponds to the range of error of measurement methods for the modulus of elasticity. [ABSTRACT FROM AUTHOR]

We discuss the universal soft behavior of form factors in the N=4 maximally supersymmetric Yang-Mills theory in the limit where the momentum of one of the particles tends to zero. We present details of how the tree-level form factors of this theory are related to eigenfunctions of a gl(4|4) integrable spin chain. [ABSTRACT FROM AUTHOR]

Techniques to image the microvasculature may play an important role in imaging tumor-related angiogenesis and vasa vasorum associated with vulnerable atherosclerotic plaques. However, the microvasculature associated with these pathologies is difficult to detect using traditional B-mode ultrasound or even harmonic imaging due to small vessel size and poor differentiation from surrounding tissue. Acoustic angiography, a microvascular imaging technique that utilizes superharmonic imaging (detection of higher order harmonics of microbubble response), can yield a much higher contrast-to-tissue ratio than second harmonic imaging methods. In this paper, two dual-frequency transducers using lateral mode transmitters were developed for superharmonic detection and acoustic angiography imaging in intracavity applications. A single element dual-frequency intravascular ultrasound transducer was developed for concept validation, which achieved larger signal amplitude, better contrast-to-noise ratio (CNR), and pulselength compared to the previous work. A dual-frequency [Pb(Mg1/3Nb2/3)O3]–x[PbTiO3] array transducer was then developed for superharmonic imaging with dynamic focusing. The axial and lateral sizes of the microbubbles in a 200- \mu \textm tube were measured to be 269 and 200~\mu \textm , respectively. The maximum CNR was calculated to be 22 dB. These results show that superharmonic imaging with a low frequency lateral mode transmitter is a feasible alternative to thickness mode transmitters when the final transducer size requirements dictate design choices. [ABSTRACT FROM AUTHOR]