Rotational Character Research Articles

Study of fcc metal tension behaviour by crystal plasticity finite element method

The crystal plasticity finite element method has been adopted to study the plastic deformation behaviour, such as the slip system activation, the number and magnitude of the actived slip system, the rotation character and the macromechanics response of face centred cubic (fcc) single crystal metal during uniaxial tension. Five typical crystalline orientations, including four types of typical fcc texture orientation: Goss orientation, copper orientation, S orientation and brass texture, have been considered, and its effects to plastic deformation have been studied and compared. The results show that the orientation between crystalline and loading direction will influence the slipping character and the macromechanical response: the S crystalline orientation (60, 32 and 65°) has the least number of active slip system (just only 3); the brass texture (35, 45 and 0°) has the smallest magnitude of crystalline lattice rotation; and the brass texture orientation (35, 45 and 0°) has the highest yield stress value.

A Novel All-Optical Frequency-Encoded Method to Develop Arithmetic and Logic Unit (ALU) Using Semiconductor Optical Amplifiers

An all-optical arithmetic and logic unit is the integral part of optical computing and data processing. In this paper, the author proposes a method to develop an all-optical arithmetic and logic unit by means of which so many binary logic operations such as AND, OR, NAND, NOR, EXOR, data comparator etc., as well as some arithmetic operations, such as half-addition, half-subtraction, full-addition, full-subtraction multiplication, etc., can be performed by properly selecting the frequencies of the control signals and using the frequency encoded input data. For this purpose, the author has exploited the frequency conversion scheme of semiconductor optical amplifier (SOA) using nonlinear polarization rotation character of the probe beam in SOA and, cross-gain modulation character of reflecting semiconductor optical amplifier (RSOA). Frequency-dependent optical beam routing to different channels have done using optical add/drop multiplexer made of SOA with multiquantum well structure. Frequency conversion efficiency of SOA and RSOA are very high as well as switching speed of SOA is very fast with very good ON-OFF contrast ratio.

Myostabilized centric relation

Intercuspation position (ICP) constitutes the occlusal reference position of the mandible while centric relation (CR) represents the articular reference position. The concept of CR depicts a key component in routine dental clinical practice due to the need for a mandibular position determined not to be dental. But a consensus on this particular topic has still not been achieved even after nearly a century of discussions with scientific and clinical arguments. A remarkable number of dental schools, restrained in their own certainty are struggling with the concept of a non-dental determined reference position, even now after many generations and decades of scientific stress. Unproductive quarrels dominate the development and consequently, a lack of reciprocal expansion of knowledge can be observed. In addition, misunderstandings bring up walls of virtual disagreements. Without pretending to have a universal knowledge, a reconnecting concept on this particular subject can be formulated, based on elementary logic and simple principles of anatomy, physiology and biomechanics. The objective of this tutorial paper is to compose and present such a concept on the basis of the scientific literature and as a synthesis of research data. The practitioner controls the homogeneity of the simple rotational character by digital perception. The absence of muscle tension (vertical oscillations) and of translation (sagittal oscillations) is an indicator for homogeneity. The patient himself gently activates his own closing movement and by doing so the correct coaptation of the condyle and disc along the articular tubercle is established. The occipital support, the light mandibular stabilization by chin control, the information of the patient before and during the procedure, the repetition of the exercise and the peripheral information through the engrammation of the localization of premature contact are parameters which facilitate the achievement of CR.

Application of Mutative Scale Chaos Search in Detecting the Rotor Orientation of Permanent Magnetic Spherical Motor

The permanent magnetic spherical stepper motor model is introduced in this paper, random encoder is painted on the rotor surface, and outputs of 96 optoelectronic sensors are used to identify rotor orientation. Based on the special structure and rotational character, the paper uses an improved mutative scale chaos search algorithm to mapping the dynamics equation of chaos variable to the orientation space. When the number of either local minima or cycles is equal to the initial value, the search space is dynamically reduced. Simulation shows that the search method is simple and has ability of fast convergence to the goal orientation, thus the search efficiency is improved.

About turn: How object orientation affects categorisation and mental rotation

High-density ERPs evoked by rotated alphanumeric characters were examined to determine how neural processing is affected by stimulus orientation during letter/digit classifications and during mirror/normal discriminations. The former task typically produces response times that are unaffected by stimulus orientation while the latter is thought to require mental rotation. Sensitivity to orientation was first observed around 100–140ms and this effect was attributed to differences in low-level features between vertical and oblique orientations. Subsequently, character misorientation amplified the N170, a neural marker of object classification, between 160 and 220ms. Top-down processing is reflected in the ERPs beginning at 280–320ms and this time range may reflect binding of ventral and dorsal stream information. In the case of mirror-normal discrimination these top-down processes can lead to mental rotation between 340 and 700ms. Therefore, although neural processing reflects object orientation, these effects do not translate into increases in reaction-times or impaired accuracy for categorisation, and precede those that do in the mental-rotation task.

Rotational and translational phonon modes in glasses composed of ellipsoidal particles

The effects of particle shape on the vibrational properties of colloidal glasses are studied experimentally. "Ellipsoidal glasses" are created by stretching polystyrene spheres to different aspect ratios and then suspending the resulting ellipsoidal particles in water at a high packing fraction. By measuring displacement correlations between particles, we extract vibrational properties of the corresponding "shadow" ellipsoidal glass with the same geometric configuration and interactions as the "source" suspension but without damping. Low-frequency modes in glasses composed of ellipsoidal particles with major-to-minor axis aspect ratios of ~1.1 are observed to have predominantly rotational character. In contrast, low-frequency modes in glasses of ellipsoidal particles with larger aspect ratios (~3.0) exhibit a mixed rotational and translational character. All glass samples were characterized by a distribution of particles with different aspect ratios. Interestingly, even within the same sample it was found that small-aspect-ratio particles participate relatively more in rotational modes, while large-aspect-ratio particles tend to participate relatively more in translational modes.

Shell model Monte Carlo approach: the heavy nuclei

The auxiliary-field Monte Carlo (AFMC) method, also known as the shell model Monte Carlo (SMMC), enables us to calculate microscopically statistical and collective properties of nuclei in the presence of strong correlations. These calculations can be carried out in shell model spaces that are many orders of magnitude larger than spaces that can be treated with conventional diagonalization methods. A recent major development has been the extension of the AFMC approach to heavy nuclei. Such applications to heavy nuclei have been a major challenge. On the conceptual level, a crucial question is whether a truncated spherical shell model Hamiltonian can describe the proper collectivity observed in heavy nuclei and, in particular, the rotational character of strongly deformed nuclei. On the technical level, the low excitation energies make it necessary to perform calculations down to much lower temperatures. At such low temperatures the propagator becomes ill-conditioned and requires the introduction of stabilization methods.

Mental Rotation Requires Visual Short-term Memory: Evidence from Human Electric Cortical Activity

The purpose of the present study was to seek evidence that mental rotation is accomplished by transforming a representation held in visual short-term memory (VSTM). In order to accomplish this goal, we utilized the sustained posterior contralateral negativity (SPCN), an electrophysiological index of the maintenance of information in VSTM. We hypothesized that if mental rotation is accomplished by transforming a representation held in VSTM, then the duration that this representation is maintained in VSTM should be related to the degree to which the representation must be rotated to reach the desired orientation. Therefore, the SPCN should offset at progressively longer latencies as the degree of rotation required increases. We tested this prediction in two experiments utilizing rotated alphanumeric characters. Experiment 1 utilized a normal versus mirror discrimination task that is known to require mental rotation. Experiment 2 utilized a letter versus digit discrimination, a task that does not require mental rotation. In Experiment 1, the offset latency of the SPCN wave increased with increases in the angle of rotation of the target. This effect indicates that targets were maintained in VSTM for longer durations as the angle of rotation increased. Experiment 2 revealed that target orientation did not affect SPCN offset latency when subjects did not adopt a mental rotation strategy, confirming that the effects on the SPCN latency effects observed in Experiment 1 were not due to the mere presentation of rotated patterns. Thus, these two experiments provide clear evidence that mental rotation involves representations maintained in VSTM.

Particle- γ spectroscopy of the ( p,d−γ ) Gd155 reaction: Neutron single-quasiparticle states at N=91

A segmented Si telescope and HPGe array is used to study the $^{156}\mathrm{Gd}$($p,d\ensuremath{-}\ensuremath{\gamma}$)$^{155}\mathrm{Gd}$ direct reaction by $d$-$\ensuremath{\gamma}$ and $d$-$\ensuremath{\gamma}$-$\ensuremath{\gamma}$ coincidence measurements using 25-MeV protons. The present investigation is the first time that this $N=91$ nucleus and the $N=90$ region---which is known for a rapid change from vibrational to rotational character, several low-lying ${0}^{+}$ states in the even-even nuclei, and large Coriolis ($\ensuremath{\Delta}\ensuremath{\Omega}=1$) plus $\ensuremath{\Delta}N=2$ mixing in the even-odd nuclei---have been studied by particle-$\ensuremath{\gamma}$ coincidence following a direct reaction with light ions. Gamma-ray energies and branches, excitation energies, angular distributions, and cross sections are measured for states directly populated in the ($p,d$) reaction. A new low-energy doublet state at 592.46 keV (previously associated with the $K=0\ensuremath{\bigotimes}{\frac{3}{2}}^{\ensuremath{-}}[521]$ bandhead) and several new $\ensuremath{\gamma}$-ray transitions (particularly for states with excitation energies $>1$ MeV) are presented. Most notably, the previous $\ensuremath{\nu} {\frac{7}{2}}^{+}[404]$ systematics at and around the $N=90$ transition region are brought into question and reassigned as $\ensuremath{\nu} {\frac{5}{2}}^{+}[402]$. This reassignment makes the $\ensuremath{\nu} {\frac{1}{2}}^{+}[400]$, $\ensuremath{\nu} {\frac{3}{2}}^{+}[402]$, and $\ensuremath{\nu} {\frac{5}{2}}^{+}[402]$ orbitals, which originate from the $3{s}_{1/2}$, $2{d}_{3/2}$, and $2{d}_{5/2}$ spherical states, respectively, responsible for the three largest cross sections to positive-parity states in the ($p,d$)$^{155}\mathrm{Gd}$ direct reaction. These three steeply upsloping orbitals undergo $\ensuremath{\Delta}N=2$ mixing with their $N=6$ orbital partners, which are oppositely sloped with respect to deformation. The presence of these steeply sloped and crossing orbitals near the Fermi surface could weaken the monopole pairing strength and increase the quadrupole pairing strength of neighboring even-even nuclei, which would bring $\ensuremath{\nu} $2p-2h ${0}^{+}$ states below $2\ensuremath{\Delta}$. Indeed, this could account for a large number of the low-lying ${0}^{+}$ states populated in the ($p,t$)$^{154}\mathrm{Gd}$ direct reaction.

Key Role of Hydrodynamic Interactions in Colloidal Gelation

Colloidal gelation is caused by the formation of a percolated network of colloidal particles suspended in a liquid. Thus far the major transport process leading to gelation has been believed to be the brownian diffusion of particles. Contrary to this common belief, we reveal by numerical simulations that many-body hydrodynamic interactions between colloidal particles also play an essential role in gelation: They significantly promote gelation, or lower the colloid volume fraction threshold for percolation, as compared to their absence. We find that the incompressible nature of a liquid component and the resulting self-organization of hydrodynamic flow with a transverse (rotational) character are responsible for this enhancement of network-forming ability.

A novel method of developing all-optical frequency encoded memory unit exploiting nonlinear switching character of semiconductor optical amplifier

The very fast running optical memory and optical logic gates are the basic building blocks for any optical computing data processing system. Realization of a very fast memory-cell in the optical domain is very challenging. In the last two decades many methods of implementing all-optical flip-flops have been proposed. Most of these suffer from speed limitation because of low switching response of the active devices. In our present communication the authors propose a method of developing a frequency encoded memory unit based on the switching action of semiconductor optical amplifier (SOA). Nonlinear polarization rotation characters of SOA and ‘SOA based Mach-Zehnder Interferometer’ switch, i.e. ‘SOA-MZI’ switch, are exploited for the purpose of some switching action with least switching power (<−3 dB m) and high switching contrast ratio (20 dB). Here two logic states (‘0’ state and ‘1’ state) of the memory is encoded by two different frequencies, which will remain unchanged throughout the data communication irrespective of loss of light energy due to reflection, refraction, attenuation, etc. Though the SOA based switch runs with the operational speed 100 Gb/s, still due to the presence of the other optical components in the memory unit, the overall speed of the proposed system will come down to 10 Gb/s.

A Novel Algorithm for Translation, Rotation and Scale Invariant Character Recognition

This paper presents a novel algorithm, called Radial Sector Coding (RSC), for Translation, Rotation and Scale invariant character recognition. Translation invariance is obtained using Center of Mass (CoM). Scaling invariance is achieved by normalizing the features of characters. To obtain most challenging rotation invariance, RSC searches a rotation invariant Line of Reference (LoR) by exploiting the symmetry property for symmetric characters and Axis of Reference (AoR) for nonsymmetric characters. RSC uses the LoR to generate invariant topological features for different characters. The topological features are then used as inputs for a multilayer feed-forward artificial neural network (ANN). We test the proposed approach on two widely used English fonts Arial and Tahoma and got 98.6% recognition performance on average.

Basin-scale internal waves in the bottom boundary layer of ice-covered Lake Müggelsee, Germany

We performed high-resolution temperature measurements under ice cover in Lake Muggelsee, Germany, during the winter of 2005–2006. Intense seiche-like temperature oscillations developing after the ice-on have been encountered in a thin water layer above the sediments. The oscillations were initiated immediately after lake freezing by the release of the potential energy of the thermocline slope and existed for several weeks without appreciable external forcing. The oscillations were associated with a basin-scale internal waves existing in the lower stratified part of the water column. The weakness of the density stratification under ice ensured the long wave periods, exceeding the period of geostrophic inertial oscillations at the lake’s latitude. As a result, two frequency peaks were present in the oscillations corresponding to two rotational waves, one of Kelvin-wave type and another of Poincare type wave. The rotational character provided long dissipation times of the waves and allowed the oscillations to persist in lake several weeks. Temperature measurements in the upper several centimeters of the sediment demonstrated that oscillations of the near-bottom temperature produced vertical density instability and pore-water convection in the upper sediments.

Method of implementing frequency encoded multiplexer and demultiplexer systems using nonlinear semiconductor optical amplifiers

Multiplexing and demultiplexing are the essential parts of any communication network. In case of optical multiplexing and demultiplexing the coding of the data as well as the coding of control signals are most important issues. Many encoding/decoding mechanisms have already been developed in optical communication technology. Recently frequency encoding technique has drawn some special interest to the scientific communities. The advantage of frequency encoding technique over any other techniques is that as the frequency is fundamental character of any signal so it remains unaltered in reflection, refraction, absorption, etc. during transmission of the signal and therefore the system will execute the operation with reliability. On the other hand, the switching speed of semiconductor optical amplifiers (SOA) is sufficiently high with property of best on/off contrast ratio. In our present communication we propose a method of implementing a ‘4-to-1’ multiplexer (MUX) and a ‘1-to-4’ demultiplexer (DEMUX) exploiting the switching character of nonlinear SOA with the use of frequency encoded control signals. To implement the ‘4-to-1’ MUX and ‘1-to-4’ DEMUX system, the frequency selection by multiquantum well (MQW)-grating filter-based SOA has been used for frequency routing purpose. At the same time, the polarization rotation character of SOA has also been exploited to get the desired purpose. Here the fast switching action of SOA with reliable frequency encoded control input signals, it is possible to achieve a faithful MUX/DEMUX service at tera-Hz operational speed.

Two types of differential rotation of the solar corona

The differential rotation of the solar corona has been analyzed using as the input data the brightness of the coronal green line Fe xiv 530.3nm for more than five activity cycles. It is found that the character of rotation of the solar corona changes during the activity cycle. Approximately at the middle of the descending branch the differential rotation is weakly pronounced, while the greatest differential gradient is observed at the ascending branch and, occasionally, at the maximum of the cycle. An explanation of this difference has been suggested. The total rotation rate of the corona can be represented as a superposition of two rotation modes (components) – the fast and slow ones. The synodic period of the fast mode near the equator is about 27 days, increasing slightly with latitude. The synodic period of the slow mode exceeds 30 days. The changing relative fraction of these two modes results in variation of the latitude dependence of the observed rotation rate during the activity cycle. The characteristics of two principal types of differential rotation of the solar corona have been determined. The first type consists of the fast mode alone and is established approximately at the middle of the descending branch of the cycle. The second type is the sum of both modes with the fast mode dominating at low latitudes and the slow mode at high latitudes. The results obtained can be used for in-depth study of interaction of the velocity field and dynamo mechanism in the Sun and stars.

Heavy Deformed Nuclei in the Shell Model Monte Carlo Method

We extend the shell model Monte Carlo approach to heavy deformed nuclei using a new proton-neutron formalism. The low excitation energies of such nuclei necessitate low-temperature calculations, for which a stabilization method is implemented in the canonical ensemble. We apply the method to study a well-deformed rare-earth nucleus, 162Dy. The single-particle model space includes the 50-82 shell plus 1f_{7/2} orbital for protons and the 82-126 shell plus 0h_{11/2}, 1g_{9/2} orbitals for neutrons. We show that the spherical shell model reproduces well the rotational character of 162Dy within this model space. We also calculate the level density of 162Dy and find it to be in excellent agreement with the experimental level density, which we extract from several experiments.

A mesoscale vortex in a small stratified lake

A mesoscale vortex structure in the small stratified Lake Stechlin has been revealed by field experiments with satellite-tracked quasi-lagrangian drifters. The vortex with a radius of about 200 m drifted at 300 m/day along the western bight of the lake with nearly constant rotation speed of 3 cpd. Analysis of kinematical properties of the vortex motion demonstrates solid body character of rotation. Extrapolation of the vortex drift trajectory over the period preceding the observations combined with data on local winds and seiche dynamics has allowed tracing the vortex fate from its generation point. The normal modes analysis of the internal seiching in the lake reveals the vortex generation mechanism to be the interaction of certain seiche modes with local bottom topography and suggests generation of the mesoscale vortices to be the a regular feature of the lake circulation. Analysis of vorticity suggests additional energy supply to rotational flow, possibly from inverse cascading of small-scale turbulent motions—a feature typical for quasi-2D turbulence. The vortices can play an important role in the energy transport from basin-scale motions to small-scale boundary mixing. They can also contribute significantly to the horizontal heterogeneity of phyto- and zooplankton distribution as well as to the transport of dissolved matter such as nutrients between littoral and profundal areas. The topographically generated traveling vortices represent an analog of the synoptic eddies in the Ocean and in the Atmosphere, whereas their role in the lake hydrodynamics is practically unknown.

Solvent and lipid dynamics of hydrated lipid bilayers by incoherent quasielastic neutron scattering

The microscopic dynamics of the planar, multilamellar lipid bilayer system 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) has been investigated using quasielastic neutron scattering. The DMPC was hydrated to a level corresponding to approximately nine water molecules per lipid molecule. Selective deuteration has been used to separately extract the dynamics of the water, the acyl chains, and the polar head groups from the strong incoherent scattering of the remaining hydrogen atoms. Furthermore, the motions parallel and perpendicular to the bilayers were probed by using two different sample orientations relative to the incident neutron beam. For both sample orientations, the results showed an onset of water motions at 260 K on the experimental time scale of about 100 ps. From lack of wave-vector dependence of the onset temperature for water motions, it is evident that the observed water dynamics is of mainly rotational character at such low temperatures. At 290 K, i.e., slightly below the gel-to-liquid transition around 295 K, the nature of the water dynamics had changed to a more translational character, well described by a jump-diffusion model. On the limited experimental time and length (about 10 A) scales, this jump-diffusion process was isotropic, despite the very anisotropic system. The acyl chains exhibited a weak onset of anharmonic motions already at 120 K, probably due to conformational changes (trans-gauche and/or syn-anti) in the plane of the lipid bilayers. Other anharmonic motions were not observed on the experimental time scale until temperature had been reached above the gel-to-liquid transition around 295 K, where the acyl chains start to show more substantial motions.

Transient growth and coupling of vortex and wave modes in self-gravitating gaseous discs

Linear transient phenomena induced by flow non-normality in thin self-gravitating astrophysical discs are studied using the shearing sheet approximation. The considered system includes two modes of perturbations: vortex and (spiral density) wave. It is shown that self-gravity considerably alters the vortex mode dynamics; its transient (swing) growth may be several orders of magnitude stronger than in the non-self-gravitating case and two to three times larger than the transient growth of the wave mode. Based on this finding, we comment on the role of vortex mode perturbations in a gravitoturbulent state. We also describe the linear coupling of the perturbation modes, caused by the differential character of disc rotation. The coupling is asymmetric: vortex mode perturbations are able to excite wave mode perturbations, but not vice versa. This asymmetric coupling lends additional significance to the vortex mode as a participant in spiral density waves and shock manifestations in astrophysical discs.

Cis/trans configurations of the peptide CN bonds: isomerization and photoswitching

AbstractCis/trans isomerization of peptide CN bonds is involved in the configurational changes and are definitive for the bioactivity of peptides and proteins. The basic molecular character and origin of the restricted rotation of the peptide CN bonds are briefly introduced, as well as the methods used for study of the cis/trans isomerization, such as the chymotrypsin‐coupled assay, pH‐mediated solvent jump, and UV‐resonance Raman spectroscopy, etc. The control of the peptide bond configuration with photoresponsive (photochromic) groups such as azobenzene or thioamide bonds is also reviewed. Copyright © 2007 John Wiley &amp; Sons, Ltd.