Orientation Of Momentum Research Articles

Circular motion and collisions of charged spinning particles near Kerr Newman black holes

We investigate the dynamics of spinning particles with an electric charge orbiting electrically charged Kerr–Newman black holes. First, we derive the equations of motion for the test particles using the Mathisson-Papapetrou-Dixon (MPD) equations, taking into account electromagnetic interaction and the interaction between the particle spin and the spacetime curvature known as the Lorentz coupling term in the MPD equation. We analyze the related effective potential in various scenarios of particle spin, angular momentum, and black hole spin orientation. In addition, we provide graphical analyses of the radius of innermost stable circular orbits (ISCOs) of the particles, their angular momentum, and energy at ISCOs and superluminal bounds. The ISCOs for positive and negatively charged particles are almost the same. The combined effects of the black hole and particle spins enhance the Coulomb interaction effect on the ISCO radius. The ISCO energy and angular momentum decrease with the increase in particle spin. In the Reissner–Nordström (RN) black hole limit, the decreasing rate is faster at positive values of the particle spin, and the spin limit changes in the Kerr–Newman black hole case. Finally, we study collisions between spinning charged particles near Kerr–Newman black holes. The critical values of the angular momentum of spinning charged particles are explored, and the particles can collide in various cases of particle and black hole spin, as well as the particle angular momentum. We also analyze electromagnetic and spin effects on the center-of-mass energy of the colliding particles.

Expensive anomalies

We show that thirteen well-known stock market anomalies have higher future abnormal returns when they exhibit a value orientation with respect to their historical levels. We find anomalies that exhibit a value orientation (cheap) outperform anomalies that exhibit a growth orientation (expensive) going forward by about 30 basis points (bps) per month. Furthermore, we find favorable anomalies based on combined value and momentum orientations outperform unfavorable anomalies by about 90 bps per month and exhibit more than double the Sharpe ratios. Alternatively, over 96 % of the dollar return for the 13 anomalies disappears when they have negative-momentum and expensive orientations.

Study of the azimuthal asymmetry in heavy ion collisions combining initial state momentum orientation and final state collective effects

Study of the azimuthal asymmetry in heavy ion collisions combining initial state momentum orientation and final state collective effects

Highly localized continuous wave optical vortex with controllable orbital angular momentum orientation and topological charge.

We report an approach to simultaneously control orbital angular momentum (OAM) orientation and topological charge in highly localized optical vortices by employing a 4π focusing system. The required continuous wave illumination field in the pupil planes is derived by superimposing the radiation pattern of only one dipole placed at the focal point of the high numerical aperture lens and the corresponding tailored spiral phase factor. The topological charge and OAM orientation of the obtained focused fields are quantitatively evaluated based on the focal field distributions calculated by the Richards-Wolf vector diffraction integration theory. Results show that the OAM of the generated optical vortices can be tailored by changing the oscillation orientation of the mimic dipole and the topological charge of the superimposed spiral phase term. The presented method may find potential applications in optical trapping, optical tweezers, light-matter interaction, etc.

Preliminary bibliometrics of plant-derived health foods over the last decade in the Scopus database

A growing interest in the medicinal values of foods can be assessed by the rapidity of research publications on foods that exert health benefits. Many foods that are of health benefit to humans, irrespective of their origin (plants, animals) and subjected level of processing (fermentation, cooking, warming, freezing, vacuum-packaging), are variously designated in scientific literature based on their biofunction. Plant-based foods’ application vagaries, momentum, and research orientation regarding their health functionality awareness are scarcely studied by bibliometrics from a global perspective. Therefore, a bibliometric search was performed on the Scopus database from 2011 (January) to 2021 (April) using a range of search keys covering reports of conceptualized consumable plant-derived foods with health-promoting potential. A total of 362,309 documents on medicinal foods of plant origin were obtained from the database. The data were obtained in comma-separated values (CSV) format and analyzed with Microsoft Excel tools. Of the total documents from the Scopus database on the study, 8.01% (29,036) were contributed by African researchers. Comparatively, lead contributors (global; Africa) by group disciplines include biochemistry, genetics, and molecular biology (118,896; 8,236); pharmacology, toxicology, and pharmaceutics (104,530; 8,581); agricultural and biological sciences (99,053; 9,610), respectively. Similarly, lead contributors by country include China (73,977), India (44,898), USA (44,582), and Nigeria (4,680). This observation shows a higher research propensity towards plant-derived medicinal foods in populous nations due to factors like dietary culture, an increase in vegan and health-nutrition enthusiast populations, and the emergent concerns with the therapeutic use of synthetic pharmaceuticals. The analyzed results gave insights into the research orientation of plant-based foods that promote human health on a global stage and provide future research directions. Knowledge of the various application of plant-based foods may potentiate the United Nations Sustainable Goals initiative on responsible consumption (SDG 12), and health and wellbeing (SDG 3) among the global population. Key words: medicinal plants, health food, nutraceuticals, dietetics, indexation, health, bibliometrics

Coulomb potential determining terahertz polarization in a two-color laser field.

The orientation and ellipticity of terahertz (THz) polarization generated by a two-color strong field not only casts light on underlying mechanisms of laser-matter interaction, but also plays an important role for various applications. We develop the Coulomb-corrected classical trajectory Monte Carlo (CTMC) method to well reproduce the joint measurements, that the THz polarization generated by the linearly polarized 800 nm and circularly polarized 400 nm fields is independent on two-color phase delay. The trajectory analysis shows that the Coulomb potential twists the THz polarization by deflecting the orientation of asymptotic momentum of electron trajectories. Further, the CTMC calculations predict that, the two-color mid-infrared field can effectively accelerate the electron rapidly away from the parent core to relieve the disturbance of Coulomb potential, and simultaneously create large transverse acceleration of trajectories, leading to the circularly polarized THz radiation.

Ballistic-electron coherent spin precession in a Rashba two-dimensional electron system

In a remarkable manifestation of the Rashba spin-orbit coupling effect, spin polarized carriers injected into a narrow two-dimensional electron system channel have ballistic trajectories and a weakly relativistic Fermi velocity. In the carrier rest frame, the intrinsic electric field in the quantum well transforms as an effective magnetic field, ${H}^{*}$, transverse to the trajectories. Electrons with initial spin momentum and polarization orientations along the channel precess because of ${H}^{*}$ with a wavelength $\ensuremath{\lambda}$. For long mean free paths $l$, spin detection probes at distances $L$ $l$ record conductance oscillations with wavelength $\ensuremath{\lambda}$. Two unique experiments that demonstrate these oscillations are discussed.

Phase diagrams for two-component D-wave fermion superfluids with density imbalance

Finite-temperature phase structures for asymmetric two-component D-wave fermion superfluids in the weak coupling BCS regime are investigated. The Fulde–Ferrell–Larkin-Ovchinnikov (FFLO) state becomes non-degenerate with the orientation of Cooper pair momentum due to the anisotropic pairing gap for D-wave pairing. The new parameter θ 0, corresponding to the orientation of Cooper pair momentum, greatly enriches the phase structures. Especially, the phase separation (PS) region in the phase diagram is significantly reduced comparing to that for S-wave pairing. Theoretically, the stability condition of solutions is equivalent to the positive definite Hessian matrix of free energy in the hyperplane defined by the number density constraints in the parameter space spanned by the average chemical potential μ, relative chemical potential h, paring gap Δ, pair momentum q, and θ 0. In addition, the stability condition of the superfluid density is essentially included in the positive definite Hessian matrix. Moreover, the positiveness of imbalance number susceptibility is always equivalent to the positiveness of the smaller eigenvalue λ − of the number susceptibility matrix. While the criteria ∂2Ω/∂Δ2 and against PS in previous studies are equivalent to λ − only under the prerequisite that the solution is a local minimum in the corresponding hyperplane.

Supercurrent-induced long-range triplet correlations and controllable Josephson effect in superconductor/ferromagnet hybrids with extrinsic spin-orbit coupling

We predict that long-range triplet correlations (LRTC) in superconductor/ferromagnet (S/F) hybrids with extrinsic impurity spin-orbit coupling can be generated and manipulated by supercurrent flowing in the superconducting leads along the S/F interfaces. The LRTC appear via two basic mechanisms. The essence of the first one is the generation of triplets by the superconducting spin Hall effect. These pairs are long range in the ferromagnet under the appropriate mutual orientation of the condensate momentum and the ferromagnet magnetization. The second mechanism is based on the singlet-triplet conversion at the S/F interface followed by the rotation of the spin of the obtained short-range opposite-spin pairs via the spin current swapping mechanism. The structure of the supercurrent-induced LRTC is studied both for S/F bilayers and superconductor/ferromagnet/superconductor (S/F/S) Josephson junctions. We demonstrate that in S/F/S junctions, where the Josephson coupling is realized via the supercurrent-induced LRTC, the ground state phase can be switched between 0 and $\ensuremath{\pi}$ in a controllable manner. The switching is performed by reversing the supercurrent in one of the superconducting leads, thus realizing a physical principle of the $\text{0-}\ensuremath{\pi}$ shifter.

Spatiotemporal optical vortices with arbitrary orbital angular momentum orientation by astigmatic mode converters

Abstract We generate a spatiotemporal optical vortex (STOV) with tunable orbital angular momentum (OAM) orientation by a simple lens system. We utilize a cylindrical lens system, which is an astigmatic mode converter, to add longitudinal angular momentum to tilt the purely transverse OAM in an arbitrary direction. The amount of tilt is tunable by adjusting the lens system, and thus the OAM direction is continuously adjustable. STOVs with adjustable OAM directions have been verified theoretically and experimentally. We believe such direction controllable OAMs will enrich future applications.

Dissipation-relaxation dynamics of a spin- 12 particle with a Rashba-type spin-orbit coupling in an ohmic heat bath

Spin-orbit coupling (SOC), which is inherent to a Dirac particle that moves under the influence of electromagnetic fields, manifests itself in a variety of physical systems including non-relativistic ones. For instance, it plays an essential role in spintronics developed in the past few decades, particularly by controlling spin current generation and relaxation. In the present work, by using an extended Caldeira-Leggett model, we elucidate how the interplay between spin relaxation and momentum dissipation of an open system of a single spin-$1/2$ particle with a Rashba type SOC is induced by the interactions with a spinless, three-dimensional environment. Staring from the path integral formulation for the reduced density matrix of the system, we have derived a set of coupled nonlinear equations that consists of a quasi-classical Langevin equation for the momentum with a frictional term and a spin precession equation. The spin precesses around the effective magnetic field generated by both the SOC and the frictional term. It is found from analytical and numerical solutions to these equations that a spin torque effect included in the effective magnetic field causes a spin relaxation and that the spin and momentum orientations after a long time evolution are largely controlled by the Rashba coupling strength. Such a spin relaxation mechanism is qualitatively different from, e.g., the one encountered in semiconductors where essentially no momentum dissipation occurs due to the Pauli blocking.

Study of Spatial Orientation of Angular Momentum of z-Magnitude SDSS DR-13 Galaxies with Red Shift 0.50 to 0.53

The spatial orientations of 142,929 SDSS DR-13, z- magnitude galaxies having red shift 0.50 to 0.53 have been analyzed. The main goal of this work is to examine the orientation of the angular momentum of galaxies within the given redshift limit in the framework of three different scenarios 'Hierarchy model', 'Pancake model', and the 'Primordial vorticity model'. By using Godlowskian transformation the two-dimensional data were converted into three-dimensional data (polar and azimuthal angles). The expected isotropy distribution curves were obtained by removing the selection effects and performing a random simulation to generate 107 virtual galaxies by using Matlab 2015a. Three statistical tests of Chi-square, autocorrelation, and Fourier were used to compare the expected isotropic data with observed. The data classified into nine subsamples having each of one magnitude size. In general, the results supported the Hierarchy model. The model advocates random orientations of angular. However, a local anisotropy observed in few subsamples suggested a gravitational tidal interaction between neighboring galaxies, an early-merging process in which the angular momentum vector distorts the initial alignment of nearby galaxies.

Controlling rotation in the molecular frame with an optical centrifuge

We computationally demonstrate a new method for coherently controlling the rotation-axis direction in asymmetric top molecules with an optical centrifuge. Appropriately chosen electric-field strengths and the centrifuge's acceleration rate allow to generate a nearly arbitrary rotational wavepacket. For D$_2$S and 2H-imidazole (C$_3$H$_4$N$_2$) we created wavepackets at large values of the rotational quantum number $J$ with the desired projections of the total angular momentum onto two of the molecules' principal axes of inertia. One application of the new method is three-dimensional alignment with a molecular axis aligned along the laser's wave vector, which is important for the three-dimensional imaging of molecules yet not accessible in standard approaches. The simultaneous orientation of the angular momentum in the laboratory frame and in the molecular frame could also be used in robust control of scattering experiments.

Spatial Orientations of Angular Momentum Vectors of Galaxies in Supercluster S [247+040+0029] and Substructures

We present an analysis of spatial orientations of 1331 galaxies in the supercluster S [247+040+0029]. The main goal of this work is to search for a new substructure candidate and examine the orientation of angular momentum in the framework of three different scenarios (hierarchy, pancake, and primordial vorticity models) using “position angle-inclination method”, and to test the dependence on magnitude with the angular momentum orientations and their projections. We identified five substructures studying number density contour map with considerably high concentration of galaxies. Using random simulation method to remove the selection effect on database, we carried out expected isotropic distribution using cosmological principle. We then used three statistical tests: Chi-square, Auto-correlation, and Fourier to identify isotropy between observed and expected isotropic distributions. We varied radius in the range 0.3° to 1.0° to find substructures in supercluster. From this we found five sub-structures when taking radius 0.3° and two substructures for 1.0° radius in the number density counter maps of galaxies. By analyzing the result obtained through statistical tests, we are able to conform that evolution of galaxy in the supercluster and substructures supports “Hierarchy model" giving the angular momentum of galaxies in the large scale structure tends to be oriented random with respect to the reference coordinate system.

The Formation of Supermassive Black Holes at Early Universe

The high-redshift universe is now the frontier of modern astronomy, and is the key object for current and near-future telescopes. The high-redshift quasars put a tight constraint on existing BH growth model, as it is challenging to form a 1010 M⊙ BH at z∼6.In this work, we relax the widely-adopted Salpeter BH growth model, to consider a more realistic path. We consider the variation in the mass and angular momentum orientation of gas supply (i.e. through ∊L and n), as well as the change in accretion mode (hot versus cold). Moreover, the conventionally considered BH spin impact on the radiative efficiency ∊M is also taken into account. Our key results can be summarized as follows. Firstly, sufficient gas supply (larger in ∊L) is obviously a key factor to make the BH grow efficiently. Also, The BH spin (a*), through the radiative efficiency ∊M, has a dominant impact on the BH growth, i.e., those high-redshift quasars with MBH > 1010 M⊙ should be formed in a chaotic gas supply situation, where the angular momentum orientation of the gas is random. Finally, through analyzing the most realistic accretion model, we find that the only existing model of seed BH is through the direct collapse, driven by either dynamical processes or thermodynamics

New Tunable High Gradient Permanent Magnet Quadrupole for Plasma Wake Field Acceleration at SPARC _LAB

Applications such as colliders and plasma wake field acceleration require high gradient quadrupoles, in the range of 400-500 T/m and with a bore of few millimeters in diameter.The design of a tunable high gradient permanent magnet quadrupole (PMQ), based on the QUAPEVA design [1] developed for the SOLEIL synchrotron, is presented. The quadrupole has a fixed part made of a Halbach quadrupole array [3, 4] surrounded by four permanent magnet cylinders with a radial orientation of the magnetic momentum. The gradient is regulated by rotating the cylinders, reaching a tunability greater than the 25%.The quadrupole has been designed for the COMB plasma wake field beam driven experiment for the SPARC_LAB test-facility at INFN-LNF [2], one of the candidates to host the EuPRAXIA project [7, 8]. The present layout foresees two triplets where the focusing strength tuning is performed by moving two quadrupoles of each triplet along the beam axis. The new quadrupoles have bigger gradient and less multipolar content than actual ones, moreover it has a tuning system that does not need any shift of the magnet.

Binary white dwarfs and decihertz gravitational wave observations: From the Hubble constant to supernova astrophysics

Context. Coalescences of binary white dwarfs represent a copious source of information for gravitational wave interferometers operating in the decihertz band. Moreover, according to the double degenerate scenario, they have been suggested to be possible progenitors of supernovae (SNe) Type Ia events. Aims. In this paper we discuss the detectability of gravitational waves emitted by the inspiral of double white dwarfs. We focus on the constraints that can be derived on the source’s luminosity distance, and on other binary’s parameters, such as the angular momentum orientation. Methods. We explore the possibility of coincident detections of gravitational and electromagnetic signals; the latter comes from the observation of the supernova counterpart. Confirmation of the double degenerate scenario would allow one to use distances inferred in the gravitational wave channel to consistently calibrate SNe as standard candles. Results. We find that decihertz gravitational wave interferometers can measure the luminosity distance with relative accuracy better than 1% for binaries at 100 Mpc. We show how multimessenger observations can put strong constraints on the Hubble constant, which are tighter than current bounds at low redshift, and how they can potentially shed new light on the differences with early-universe measurements.

Механизм открытия щели в точке Дирака в электронном спектре Gd-допированного топологического изолятора

The electronic structure of magnetically-doped TI with stoichiometry Bi1.09Gd0.06Sb0.85Te3 in the region of the Dirac point has been studied in detail by angle-resolved photoelectron spectroscopy (ARPES) at various temperatures (above and below the Néel temperature, 1-35 K) and different polarizations of synchrotron radiation. It has shown that the energy gap in photoemission spectra opens at the Dirac point and remains open above the temperature of the long-range magnetic ordering, Tn. Measurements of magnetic properties by the superconducting magnetometry method (SQUID) have shown antiferromagnetic ordering with a transition temperature to the paramagnetic phase equal to 8.3 K. Study of the temperature dependence of the Dirac cone state intensity at the Г point by ARPES has confirmed the magnetic transition and has shown a possibility of its indication directly from photoemission spectra. A more detailed analysis of the splitting between the upper and lower Dirac cone states (i.e. the energy gap) at the Dirac point in the photoelectron spectra has shown the dependence of the measured gap on the synchrotron radiation polarization (about 28-30 meV for p-polarization and 22-25 meV for circularly polarized radiation of opposite chirality). The mechanism of opening the gap at a Dirac point above the Tn was proposed due to the “pairing” of the Dirac fermions with opposite momentum and spin orientation as a result of their interaction with the spin texture generated by photoemission in the region of the photoemission hole on a magnetic impurity atom (Gd). It was shown that the gap at the Dirac point, measured above Tn, is dynamic and is formed directly during photoemission process. At the same time, the origin of the gap remains magnetic (even when the long-range magnetic ordering is destroyed) and is associated with the properties of the magnetic topological insulator that determines a practically unchanged size of the gap above Tn. The dynamic origin of the generated gap is confirmed by the dependence of its magnitude on the polarization of synchrotron radiation.

Cloudlet capture by transitional disk and FU Orionis stars

After its formation, a young star spends some time traversing the molecular cloud complex in which it was born. It is therefore not unlikely that, well after the initial cloud collapse event which produced the star, it will encounter one or more low mass cloud fragments, which we call “cloudlets” to distinguish them from full-fledged molecular clouds. Some of this cloudlet material may accrete onto the star+disk system, while other material may fly by in a hyperbolic orbit. In contrast to the original cloud collapse event, this process will be a “cloudlet flyby” and/or “cloudlet capture” event: A Bondi–Hoyle–Lyttleton type accretion event, driven by the relative velocity between the star and the cloudlet. As we will show in this paper, if the cloudlet is small enough and has an impact parameter similar or less than GM*/v∞2 (with v∞ being the approach velocity), such a flyby and/or capture event would lead to arc-shaped or tail-shaped reflection nebulosity near the star. Those shapes of reflection nebulosity can be seen around several transitional disks and FU Orionis stars. Although the masses in the those arcs appears to be much less than the disk masses in these sources, we speculate that higher-mass cloudlet capture events may also happen occasionally. If so, they may lead to the tilting of the outer disk, because the newly infalling matter will have an angular momentum orientation entirely unrelated to that of the disk. This may be one possible explanation for the highly warped/tilted inner/outer disk geometries found in several transitional disks. We also speculate that such events, if massive enough, may lead to FU Orionis outbursts.

Combined flow-based imaging assessment of optimal cardiac resynchronization therapy pacing vector: a\xa0case report

BackgroundThere are still many pendent issues about the effective evaluation of cardiac resynchronization therapy impact on functional mitral regurgitation. In order to reduce the intrinsic difficulties of quantification of functional mitral regurgitation itself, an automatic quantification of real-time three-dimensional full-volume color Doppler transthoracic echocardiography was proposed as a new, rapid, and accurate method for the assessment of functional mitral regurgitation severity. Recent studies suggested that images of left ventricle flow by echo-particle imaging velocimetry could be a useful marker of synchrony. Echo-particle imaging velocimetry has shown that regional anomalies of synchrony/synergy of the left ventricle are related to the alteration, reduction, or suppression of the physiological intracavitary pressure gradients.Case summaryWe describe a case in which the two technologies are used in combination during acute echocardiographic optimization of left pacing vector in a 63-year-old man, Caucasian, who showed worsening heart failure symptoms a few days after an implant, and the effect of the device’s optimization at 6-month follow-up.DiscussionThe degree of realignment of hemodynamic forces, with quantitative analysis of the orientation of blood flow momentum (φ), can represent improvement of fluid dynamics synchrony of the left ventricle, and explain, with a new deterministic parameter, the effects of cardiac resynchronization therapy on functional mitral regurgitation. Real-time three-dimensional color flow Doppler quantification is feasible and accurate for measurement of mitral inflow, left ventricular outflow stroke volumes, and functional mitral regurgitation severity.ConclusionThis clinical case offers an innovative and accurate approach for acute echocardiographic optimization of left pacing vector. It shows clinical utility of combined three-dimensional full-volume color Doppler transthoracic echocardiography/echo-particle imaging velocimetry assessment to increase response to cardiac resynchronization therapy, in terms of reduction of functional mitral regurgitation, improving fluid dynamics synchrony of the left ventricle.