Phenomenon Of Alignment Research Articles

The phenomenon of alignment in cosmic rays and analyzing azimuthal anisotropy on the large hadron collider

The phenomenon of alignment discovered in experiments with emulsion chambers is a consequence of the coplanar scatter of secondary particles in nuclear interaction at very high energies (>1016 eV). The possibility of a correlation between the alignment effect and the generation of QCD jets is considered. Criteria and methods for analyzing the correlation between the alignment phenomenon and events with unusual topology on the LHC are proposed

DYNAMIC ALIGNMENT AND EXACT SCALING LAWS IN MAGNETOHYDRODYNAMIC TURBULENCE

Magnetohydrodynamic (MHD) turbulence is pervasive in astrophysical systems. Recent high-resolution numerical simulations suggest that the energy spectrum of strong incompressible MHD turbulence is E(k ⊥) ∝ k –3/2 ⊥. So far, there has been no phenomenological theory that simultaneously explains this spectrum and satisfies the exact analytic relations for MHD turbulence due to Politano & Pouquet. Indeed, the Politano-Pouquet relations are often invoked to suggest that the spectrum of MHD turbulence instead has the Kolmogorov scaling –5/3. Using geometrical arguments and numerical tests, here we analyze this seeming contradiction and demonstrate that the –3/2 scaling and the Politano-Pouquet relations are reconciled by the phenomenon of scale-dependent dynamic alignment that was recently discovered in MHD turbulence.

Prosodic alignment in human–computer interaction

Androids that replicate humans in form also need to replicate them in behaviour to achieve a high level of believability or lifelikeness. We explore the minimal social cues that can induce in people the human tendency for social acceptance, or ethopoeia, toward artifacts, including androids. It has been observed that people exhibit a strong tendency to adjust to each other, through a number of speech and language features in human–human conversational interactions, to obtain communication efficiency and emotional engagement. We investigate in this paper the phenomena related to prosodic alignment in human–computer interactions, with particular focus on human–computer alignment of speech characteristics. We found that people exhibit unidirectional and spontaneous short-term alignment of loudness and response latency in their speech in response to computer-generated speech. We believe this phenomenon of prosodic alignment provides one of the key components for building social acceptance of androids.

Mechanism of Shear-Induced Alignment in Bilayer Thin Films of Spherical Particles

The phenomenon of shear-induced alignment in polycrystalline bilayer systems is analyzed using Brownian dynamics simulations. We show that the alignment process can be explained in terms of a local grain boundary migration mechanism. Both microscopic and continuum models are constructed that predict the boundary migration velocity as a function of local structure and shear stress. In the continuum picture, shear-induced potential energy gradients act as the driving force for migration, and the grain boundary mobility is sensitive to the degree of misorientation between the grains.

Alignment effects and the nuclear composition of primary particles

The phenomenon of alignment of the highest energy secondary particles into a line, which was revealed in experiments with X-ray emulsion chambers, has not found satisfactory interpretation. In this context, study of the dependence of this effect on the nature of primary particles forming γ families must be of great interest. In is shown that families with aligned γ-ray photons are generally produced by primary protons.

Spatial distribution of aligned muons in groups

The phenomenon of alignment along one line for the highest energy secondary particles in the γ-ray-hadron families was observed for the first time in the “Pamir” experiment using the x-ray emulsion chambers and was related to coplanar production of secondary particles at energy E0 > 1016 eV. The distributions of distances between the muon pairs in the muon groups are obtained using the Baksan underground scintillation telescope of the Institute for Nuclear Research (Russian Academy of Sciences) for the threshold energies of 0.85–3.2 TeV for the period of 7.7 years. A difference between spatial distributions of all groups and aligned groups was not detected.

Confined Assembly in Coaxially Electrospun Block Copolymer Fibers

Electrospinning has received a lot of attention in recent years as a simple process to produce sub-micrometer-scale fibers. The process involves continuous stretching of polymer solution or melt in the presence of a strong electric field, which forms ultrathin fibers. A large amount of research is being carried out to achieve control of the diameter, morphology, and spatial alignment of electrospun nanofibers. Unlike other 1D nanostructures, such as nanowires and nanotubes, nanofibers exhibit a wide range of unique properties, making them far more attractive for many applications, such as filtration, catalysis, sensing, protective clothing, and tissueengineering scaffolds. Being a continuous process, electrospinning can produce extremely long fibers comparable to those formed via conventional mechanical drawing and spinning techniques. Nanofiber mats exhibit extremely high surface-to-mass ratios, greatly improving their efficiency for catalysis and filtration. Another fascinating feature of this process is that it can be applied to a wide variety of nanostructured materials. Bognitzki et al. fabricated sub-micrometerscale fibers by electrospinning ternary solutions of polylactide and poly(vinylpyrrolidone). They found that the fibers displayed an internal phase morphology, and, by selectively removing one phase, they obtained highly porous fibers. However, these morphologies were largely controlled by rapid phase separation and rapid solidification of the polymer jet, and no method for controlling these morphologies was demonstrated. In the present study, we utilize this simple process to fabricate block copolymer (BCP) nanofibers. BCP solutions and melts are known to self-assemble into a variety of nanoscale morphologies including spheres, rods, micelles, lamellae, vesicles, tubules, and cylinders, depending on the volume fraction and interaction parameter between different blocks. We have been able to produce macroscale-length fibers with diameters of a few hundred nanometers that exhibit internal structures of only tens of nanometers in size. Such materials, we believe, can combine the unique properties of continuous nanofibers and BCP self-assembly for use in a variety of applications of nanostructured materials. BCP self-assembly has attracted increasing interest in recent years for applications in nanotechnology. Precise control over the size, shape, and periodicity of these nanoscale microdomains is the key factor needed to realize nanoscale systems. Various methods, including shear and elongational deformation, compressional deformation, electric fields, and temperature gradients, have been utilized to induce orientation of the microdomains. To our knowledge, shear flow has been most extensively studied as a simple means to induce phase transitions and orient self-assembled structures in block copolymers. The phenomenon of flow-induced alignment of lamellar BCPs is very well studied in bulk systems. Three different orientations of lamellar morphology, namely, parallel, perpendicular, and transverse have been obtained as a function of shear rate, shear frequency, and temperature. We refer the reader to a review paper that elaborates on the various methods to control BCP microdomains and the potential applications of these domains as nanometersized membranes, templates for fabrication of a variety of nano-objects, and templates for fabrication of high-density information-storage media. Recently, some research has been carried out in order to obtain novel self-assembled structures, using the effect of confinement of self-assembling materials in 1D nanostructures, such as nanorods and nanowires. Shin et al. and Xiang et al. studied the effect of cylindrical confinement on the morphology of polystyrene-block-polybutadiene (PS-b-PBD) in nanoporous alumina membranes. They found that if the pore diameter is large compared to the equilibrium bulk spacing and one component preferentially segregates to the walls, then a symmetric copolymer forms with a concentric cylindrical morphology and alternating cylinders of PS and PBD. If the pore diameter is small and not an integer multiple of the bulk repeat period, the high degree of curvature imposed in cylindrical confinement causes frustration of chain packing at the interface, forming stacked PS lamellar structures along the axis of the pore. Wu et al. studied the confined assembly of SiO2/copolymer-composite mesostructures in cylinders of varying diameters using alumina nanochannels. They also carried out self-consistent field calculations for comparison with experimentally obtained self-assembled structures. However, potential applications of these distinctive nanostructures are C O M M U N IC A IO N

Template-free preparation of bunches of aligned manganese oxide nanowires

A simple method based on a conventional solid-state process is proposed for synthesis of manganese oxide nanowires. This method provides an opportunity for bunching the nanowires synthesized, since the nanowires form in one direction. Thus, aligned bunches (e.g. >100 µm long and about 50 µm in diameter) consisting of individual nanowires (diameters ranging between 50 and 200 nm) can be prepared simply. The phenomenon of simultaneous alignment of the nanowires in one direction to form ordered bunches is indeed an interesting development in the realm of nanotechnology. It can be considered as an alternative to conventional template-based methods.

Fiber alignment and property direction dependency of FRC extrudate

This paper studies the phenomenon of fiber alignment during the extrusion process. The fiber alignment is largely dependent on shapes of dies and the compression as well as the shear force generated in the extruder. The fiber alignment orientation, of course, would lead to direction dependency of the tensile properties of fiber-reinforced cement (FRC) extrudates. Such a dependency has been investigated in present study. It is found that when fiber volume ratio is small, say 1% of the glass fiber, the majority of the fiber can be aligned in the extrusion direction. As a result, the tensile strength of the thin plate along the extrusion direction is much higher than that along the transverse direction. When the total fiber volume ratio is increased to 2% or 4%, the fiber volume along the transverse direction is largely increased although the percentage of the fiber aligned along the extrusion direction is still higher. Thus, the tensile strength at a transverse direction can be significantly enhanced. In fact, the tensile strength of the samples along the transverse direction is almost the same as that along the extrusion direction when the fiber volume ratio reaches 2%. Furthermore, the strength of the sample at the extrusion direction does not increase proportionally to the fiber volume ratio. For the comparison purpose, plain sheets without any fibers have been prepared by both casting and extrusion. Mechanical properties of the sheets have also been tested and the test results show that extrusion process and fiber addition do have effects on enhancing the tensile properties. Polymer coating on the surface of the samples has also been used to improve the tensile properties of the extrudates with low fiber volume ratio, which shows some promising results.

Laser-induced nanoparticle ordering

Nanoparticles were produced on the surface of silicon upon pulsed-laser irradiation in the presence of an inert gas atmosphere at fluences close to the melting threshold. It was observed that nanoparticle formation required redeposition of ablated material. Redeposition took place in the form of a thin film intermixed with extremely small nanoparticles possibly formed in the gas phase. Through the use of nonpolarized laser light, it was shown that nanoparticles, fairly uniform in size, became grouped into curvilinear strings distributed with a short-range ordering. Microstructuring of part of the surface prior to the laser treatment had the remarkable effect of producing nanoparticles lying along straight and fairly long (approximately 1 mm) lines, whose spacing equaled the laser wavelength for normal beam incidence. In this work, it is shown that the use of polarized light eliminated the need of an aiding agent: nanoparticle alignment ensued under similar laser treatment conditions. The phenomenon of nanoparticle alignment bears a striking similarity with the phenomenon of laser-induced periodic surface structures (LIPSS), obeying the same dependence of line spacing upon light wavelength and beam angle of incidence as the grating spacing in LIPSS. The new results strongly support the proposition that the two phenomena, LIPSS and laser-induced nanoparticle alignment, evolve as a result of the same light interference mechanism.

Alignment of individual-particle angular momenta along the deformation axis in light nuclei

High- K rotational bands which are based on deformation-aligned multiparticle configurations of the Nilsson-model are shown to provide levels on or close to the yrast line in the s – d shell nuclei between 23 Na and 29 Si . The evidence is based on experimental data amended by results of shell model calculations which yield level energies and matrix elements of the E2 operator with proven reliability. The phenomenon of deformation alignment is completely contained in the shell model. The low excitation energies of deformation aligned states are traced back to the p – n interaction in the T=0 channel which favours parallel alignment of angular momenta. The proof uses Nilsson-model matrix elements of the residual interaction which are deduced from the experimental properties of low- K bands by a method which is due to Brink and Kerman.

Lanthanide ion assisted magnetic alignment of model membranes and macromolecules

Orientational and structural properties of membrane peptides and membrane proteins are frequently studied using solid state NMR techniques with aligned samples. Depending on the size of the protein under study, one may choose to employ bicelle or lanthanide-doped bilayer systems, which are known to spontaneously align in magnetic fields with the symmetry axes perpendicular or parallel to the magnetic field, respectively. Using an order matrix formalism, a brief description is given of the anisotropic interactions which are utilized to determine orientational and structural properties of membrane associated macromolecules. The phenomenon of magnetic alignment in these systems is reviewed with particular attention to lanthanide ion assisted alignment. Finally, several examples of lanthanide ion assisted magnetic alignment of macromolecules for high-resolution solution NMR applications are discussed. © 2001 John Wiley & Sons, Inc. Concepts Magn Reson 13: 19–31 2001

Spatial orientation of the angular vestibulo-ocular reflex

During vestibular nystagmus, optokinetic nystagmus (OKN), and optokinetic afternystagmus (OKAN), the axis of eye rotation tends to align with the vector sum of linear accelerations acting on the head. This includes gravitational acceleration and the linear accelerations generated by translation and centrifugation. We define the summed vector of gravitational and linear accelerations as gravito-inertial acceleration (GIA) and designate the phenomenon of alignment as spatial orientation of the angular vestibuloocular reflex (aVOR). On the basis of studies in the monkey, we postulated that the spatial orientation of the aVOR is dependent on the slow (velocity storage) component of the aVOR, not on the short latency, compensatory aVOR component, which is in head-fixed coordinates. Experiments in which velocity storage was abolished by midline medullary section support this postulate. The velocity storage component of the aVOR is likely to be generated in the vestibular nuclei, and its spatial orientation was shown to be controlled through the nodulus and uvula of the vestibulocerebellum. Separate regions of the nodulus/uvula appear to affect the horizontal and vertical/torsional components of the response differently. Velocity storage is weaker in humans than in monkeys, but responds in a similar fashion in both species. We postulate that spatial orientation of the aVOR plays an important role in aligning gaze with the GIA and in maintaining balance during angular locomotion.

Reply to the Comment on “Rotational Alignment in Supersonic Seeded Beams of Molecular Oxygen” (by Charles D. Pibel, Joshua B. Halpern)

Reply to the Comment on “Rotational Alignment in Supersonic Seeded Beams of Molecular Oxygen” (by Charles D. Pibel, Joshua B. Halpern)

Tutorial/Article didactique: Angular momenta dynamics in magnetic and electric field: Classical and quantum approach

A standard description of the angular momentum in atomic or molecular physics is based on quantum mechanics. However, especially at large angular-momentum limit in molecules, sometimes a classical approach greatly simplifies problems that are extremely complicated from a quantum-mechanical viewpoint. The aim of this paper is to examine the relationship between the classical and quantum descriptions of the angular-momentum distribution in an ensemble of particles. At first glance, quantum and classical approaches appear to be absolutely different and have very little in common. In this paper this relationship is analyzed. It is shown that similarities can be found between the precession of angular momentum in the external field and the influence of this field upon the wave-function phase of a microparticle. The importance of wave function phases is stressed even for stationary conditions, and some examples of coherent superposition of quantum states are presented. The general method of how to pass from the quantum approach to a classical one is formulated. Results are visualized in the form of 3D distribution functions. This approach allows a graphical interpretation and thus results in a better understanding, sometimes at first glance, of counterintuitive quantum results. As an example the phenomenon of alignment- orientation transition is considered. Rather than presenting only formal derivations, the emphasis is on the instructional aspects, and on illustrating the general approach.

Near-Atomic Resolution Imaging of Ferroelectric Liquid Crystal Molecules on Graphite by STM

Near-atomic resolution images of a two-dimensional heteroepitaxial crystal composed of the relatively "functionally rich" chiral liquid crystal mesogen MDW 74 on graphite have been obtained by scanning tunneling microscopy (STM). This work is aimed at developing an improved understanding of the commercially crucial phenomenon of liquid crystal alignment by studying well-characterized surfaces. Herein is reported molecular-level characterization of the surface underlying a ferroelectric liquid crystal in situ, a requisite starting point for understanding the liquid crystal-solid interface at the molecular level. The results are also important in the context of developing a model for the molecular. origins of the contrast observed in STM images of organic monolayers on conductor surfaces. The data and analysis provide strong evidence that neither frontier orbital alone (highest occupied or lowest unoccupied molecular orbital) is sufficient to describe the observed tunneling efficiency.

Mathematical models of wound healing in embryonic and adult epidermis.

Epidermal wound healing occurs by quite different mechanisms in embryos and adults. In the latter case, it has long been known that cells crawl inwards via lamellipodia to close the defect. In the embryonic system, recent evidence suggests that healing may be caused by a quite different mechanism, namely the contraction of a cable of filamentous actin at the wound edge. The authors use mathematical modelling to investigate both systems. A mechanical model for the initial formation of the actin cable in embryonic epidermal wounds is presented, which incorporates the important phenomenon of stress-induced microfilament alignment. Also discussed is a reaction-diffusion model for the healing of adult wounds subject to autoregulation of cell division. In both cases, the results suggest possible biological mechanisms for key aspects of the healing process.

Classical model for the spin alignment of 'odd nucleons'

A classical treatment of the 'rotor+particle' model is suggested. The classical equations of motion for this model are obtained and their general solution is given. The stationary rotations are studied in detail. Application of the model to the phenomenon of alignment of the angular momentum of 'odd nucleons' along the vector of nuclear velocity is discussed. Comparison with experiment shows good agreement with the theoretical results.

2.2 micron image of 3C 368 at Z = 1.13, a galaxy with aligned radio and stellar axes

view Abstract Citations (97) References (29) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS 2.2 Micron Image of 3C 368 at z=1.13, a Galaxy with Aligned Radio and Stellar Axes Chambers, K. C. ; Miley, G. K. ; Joyce, R. R. Abstract We present a K-band infrared image of the z = 1.13 radio galaxy 3C 368. This galaxy is one of the brightest examples of the recently discovered phenomenon of alignment between the optical and radio axes of powerful distant radio galaxies. Our observations show that the infrared morphology is also elongated and aligned along the optical and radio axes. However, it is not coincident with the radio emission. We discuss various mechanisms for producing the infrared and optical flux, and the resultant constraints on the origin of the alignment effect in high-redshift radio galaxies. The most likely explanation is that the emission is produced mainly by young stars formed by interaction of the radio source with the interstellar medium. The infrared flux is then interpreted as dominated by a population of red supergiants. Independent of the origin of the emission, the observed alignment implies that powerful radio galaxies at high redshifts are distinct from giant ellipticals, even in the infrared. Hence, attempts to derive a cosmological "standard candle" using studies which combine these two types of galaxies are likely to be invalid. Publication: The Astrophysical Journal Pub Date: June 1988 DOI: 10.1086/185180 Bibcode: 1988ApJ...329L..75C Keywords: Cosmology; Galactic Evolution; Infrared Imagery; Interstellar Matter; Radio Galaxies; Red Shift; Morphology; Radio Emission; Radio Sources (Astronomy); Star Formation; Astrophysics; COSMOLOGY; GALAXIES: EVOLUTION; GALAXIES: REDSHIFTS; GALAXIES: STELLAR CONTENT; INFRARED: GENERAL; RADIO SOURCES: GALAXIES full text sources ADS | data products SIMBAD (5) NED (3)

4C 40.36 - A radio galaxy at a redshift of 2.3

view Abstract Citations (66) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS 4C 40.36: A Radio Galaxy at a Redshift of 2.3 Chambers, K. C. ; Miley, G. K. ; van Breugel, W. J. M. Abstract We present long-slit spectroscopy of a faint extended optical object which we have identified with the radio source 4C 40.36. Three emission lines are detected. Their wavelengths match those of C IV λ1549, He II λ1640, and C III] λ1909 to within 0.5% for a redshift of z = 2.269. The extended continuum emission (~20 kpc) together with the large equivalent widths (~100 A) and narrow profiles (~1500 km s^-1^) of the emission lines, all show that 4C 40.36 is a galaxy with properties similar to those of other distant radio galaxies. The redshift of 4C 40.36, however, considerably exceeds that of the most distant radio galaxy (3C 326.1 at z = 1.825) known to date. 4C 40.36 is of additional interest as an excellent example of the recently discovered phenomenon of alignment between the optical and radio axes of powerful distant radio galaxies. The object was investigated as part of our survey of ultra-steep spectrum radio sources, and we show that the selection criteria used to discover 4C 40.36 result in a sample of objects having a relatively low dispersion of monochromatic radio luminosities. Publication: The Astrophysical Journal Pub Date: April 1988 DOI: 10.1086/185137 Bibcode: 1988ApJ...327L..47C Keywords: Cosmology; Emission Spectra; Line Spectra; Radio Galaxies; Radio Sources (Astronomy); Red Shift; Radio Emission; Stellar Luminosity; Very Large Array (Vla); Astrophysics; COSMOLOGY; GALAXIES: REDSHIFTS; RADIO SOURCES: GALAXIES full text sources ADS | data products SIMBAD (5) NED (5)