Triaxial Components Research Articles

The GOGREEN Survey: Evidence of an Excess of Quiescent Disks in Clusters at 1.0 < z < 1.4

Abstract We present the results of the measured shapes of 832 galaxies in 11 galaxy clusters at 1.0 < z < 1.4 from the GOGREEN survey. We measure the axis ratio (q), the ratio of the minor to the major axis, of the cluster galaxies from near-infrared Hubble Space Telescope imaging using Sérsic profile fitting and compare them with a field sample. We find that the median q of both star-forming and quiescent galaxies in clusters increases with stellar mass, similar to the field. Comparing the axis ratio distributions between clusters and the field in four mass bins, the distributions for star-forming galaxies in clusters are consistent with those in the field. Conversely, the distributions for quiescent galaxies in the two environments are distinct, most remarkably in 10.1 ≤ log ( M / M ⊙ ) < 10.5 where clusters show a flatter distribution, with an excess at low q. Modelling the distribution with oblate and triaxial components, we find that the cluster and field sample difference is consistent with an excess of flattened oblate quiescent galaxies in clusters. The oblate population contribution drops at high masses, resulting in a narrower q distribution in the massive population than at lower masses. Using a simple accretion model, we show that the observed q distributions and quenched fractions are consistent with a scenario where no morphological transformation occurs for the environmentally quenched population in the two intermediate-mass bins. Our results suggest that environmental quenching mechanism(s) likely produce a population that has a different morphological mix than those resulting from the dominant quenching mechanism in the field.

Triaxiality in selenium-76

Background: Selenium and germanium nuclei are associated with both triaxiality and shape coexistence. The relative influence of these deformation effects on the low-lying nuclear structure remains the subject of much discussion with additional attention drawn to $^{76}\mathrm{Se}$ and $^{76}\mathrm{Ge}$ due to the potential for the observation of neutrinoless double-$\ensuremath{\beta}$ decay.Purpose: Experimental observables related to the deformation of $^{76}\mathrm{Se}$ are lacking in precision. The purpose of the present paper is to provide electric quadrupole matrix elements with improved precision in order to determine the deformation of low-lying states in a model-independent manner.Methods: Sub-barrier Coulomb excitation was employed at the reaccelerated beam facility of the National Superconducting Cyclotron Laboratory using the JANUS setup. Using this method nineteen $E2$ matrix elements were extracted.Results: Extracted matrix elements agree within uncertainties with those in the literature but with improved precision. Through both a comparison with geometric models and a model-independent evaluation of $E2$ matrix elements using rotational invariants, the ground state of $^{76}\mathrm{Se}$ is best described as having a significant triaxial component, but is not maximally triaxially deformed.Conclusions: Selenium-76 exhibits a significant degree of triaxiality in its ground state. A detailed comparison with configuration-interaction calculations indicates that this can be well reproduced theoretically.

A fast algorithm for estimating actions in triaxial potentials

We present an approach to approximating rapidly the actions in a general triaxial potential. The method is an extension of the axisymmetric approach presented by Binney, and operates by assuming that the true potential is locally sufficiently close to some Stäckel potential. The choice of Stäckel potential and associated ellipsoidal coordinates is tailored to each individual input phase-space point. We investigate the accuracy of the method when computing actions in a triaxial Navarro–Frenk–White potential. The speed of the algorithm comes at the expense of large errors in the actions, particularly for the box orbits. However, we show that the method can be used to recover the observables of triaxial systems from given distribution functions to sufficient accuracy for the Jeans equations to be satisfied. Consequently, such models could be used to build models of external galaxies as well as triaxial components of our own Galaxy. When more accurate actions are required, this procedure can be combined with torus mapping to produce a fast convergent scheme for action estimation.

Actions, angles and frequencies for numerically integrated orbits

We present a method for extracting actions, angles and frequencies from an orbit's time series. The method recovers the generating function that maps an analytic phase-space torus to the torus to which the orbit is confined by simultaneously solving the constraints provided by each time step. We test the method by recovering the actions and frequencies of a triaxial St\"ackel potential, and use it to investigate the structure of orbits in a triaxial potential that has been fitted to our Galaxy's Sagittarius stream. The method promises to be useful for analysing N-body simulations. It also takes a step towards constructing distribution functions for the triaxial components of our Galaxy, such as the bar and dark halo.

Band structure of neutron rich Se and Ge isotopes

The band structure of the neutron-rich Se and Ge isotopes has been studied in terms of the full-fledged shell model. The monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. The model reproduces well the energy levels of high-spin states as well as the low-lying states. In order to investigate the structure of the high-spin states and low-lying collective states, the energy spectra in the shell model are compared with those in the quantum-number-projected generator coordinate method. It is shown that the triaxial components play essential roles in describing the γ bands.

Comparison of peak shoulder and elbow mechanical loads during weight-relief lifts and sitting pivot transfers among manual wheelchair users with spinal cord injury

This study compared shoulder and elbow joint forces and moments between weight-relief lifts (WRLs) and sitting pivot transfers (SPTs) among manual wheelchair users with spinal cord injury (SCI) (N = 13) during biomechanical laboratory assessment. Minimum and maximum values were reported for each triaxial component of the joint force at the dominant shoulder and elbow during SPTs (leading and trailing roles) and WRLs. Peak shoulder flexor and adductor moments, along with elbow flexor and extensor moments, observed during the same period were also analyzed. The SPTs predominantly exposed (p < 0.001) the shoulder joints to substantial posteriorly directed forces (leading = -2.6 N/kg; trailing = -3.1 N/kg) compared with WRLs (-2.2 N/kg), whereas superiorly directed forces (2.9 N/kg) were principally sustained ( p < 0.001) during WRLs compared with SPTs (leading = 1.5 N/kg; trailing = 1.5 N/kg). High superiorly directed forces (3.6 to 3.9 N/kg) were observed at the elbow, which were comparable (p = 0.33) between the two tasks. The peak shoulder flexor (leading = 1.36 N m/kg; trailing = 1.45 N m/kg) and adductor moments (leading only = -0.46 N m/kg), along with the peak elbow flexor moments (leading = 0.24 N m/kg; trailing = 0.15 N m/kg), were significantly more elevated (p < 0.021) during SPTs than during WRLs. Peak shoulder adductor (-0.46 vs -0.24 N m/kg) and elbow flexor moments were also more elevated ( p = 0.03) at the leading upper limb compared with the trailing one. The peak elbow extensor moments did not differ ( p = 0.167) between the two tasks (-0.17 to -0.25 N m/kg). SPTs exposed the shoulder and elbow joints to greater mechanical loads than WRLs among individuals with SCI.

Tri-Axial Sensors and Actuators Made of a Single Piezoelectric Cylindrical Shell

Electromechanical transducers for sensing and actuating disturbances or vibrations have been used in many fields of applications. There have been transducers of different configuration developed for the unidirectional transduction. This paper demonstrates a single element transducer for tri-axial components made of a piezoelectric cylindrical shell. The separation of the tri-axial transductions is achieved by devising a proper electrode arrangement. The structure and the fundamental idea are first presented, and then the numerical analysis by means of the finite element modeling follows, and their characteristics and behaviors are then experimentally verified.

Determining Angular Velocity and Angular Acceleration of Projectiles Using Triaxial Acceleration Measurements

Estimation of body frame components of angular velocity and angular acceleration of a projectile undergoing general three-dimensional motion using linear acceleration measurements is considered. For the case where triaxial components of linear acceleration are known at three noncolinear points, the kinematic equations must in general be transformed to a computational plane before a useful solution is obtained. However, when more than three point measurements are utilized, a solution is obtained without the need to transform the kinematic equations to a computational plane. The sensitivity of angular rates to measurement errors is a nonlinear function of angular rates and sensor geometry. For a body that nutates and precesses as it rolls, large errors can be induced for some combinations of angular rates and sensor configurations. However, utilization of acceleration measurements at many points on the skin of an atmospheric rocket can effectively estimate the angular rates and accelerations with noisy, quantized acceleration measurements.

Long-time creep fracture data on 1/2 CrMoV Steel and their application to design

AbstractThe results of 46 tensile creep tests at seven temperature levels are reported along with a single solid torsion test at each temperature over the range 450-600°C, with a longest time to fracture of 132000 h. The torsion tests show the multiaxial stress criterion for creep fracture to be the octahedral shear stress. Analysis of the data leads to a constitutive equation which can be applied to the prediction ofcreep fracture of components using the skeletal point technique. Experimental and predicted behaviour ofsimple biaxial and triaxial components are examined.

Structural and Magnetic Properties of Epitaxial Permalloy Films

AbstractA study is made of the structural and magnetic properties of (111) films of permalloy (80% Ni, 20% Fe), produced epitaxially (111) Ag on mica. The orientation of the NiFe is parallel to that of the Ag. The anisotropy field is about 2 Oe, and the coercive force is slightly less than this value. The dispersion, α90, is of the order of a degree. The films are largely uniaxial, with a superimposed triaxial component. The presence of a triaxial component is demonstrated by the slow switching properties of the permalloy films, and by their domain structures. It seems that the reversal process, away from the easy axis, is a partial rotation.