Angular Alignments Research Articles

Angular and torsional malalignments of the paediatric knee joint

Abnormal angular and torsional alignment of the lower extremities during growth are acommon reason for consultation of apaediatrician or orthopaedist. There is often uncertainty about the pathological value of these abnormalities and the need for treatment, even among specialists. In the course of physiological growth and development processes, the axial and torsional alignment of the legs sometimes change considerably and in characteristic patterns. The ability to assess whether abnormal angular or torsional alignments of the lower limb in the course of growth should still be regarded as normal or already as pathological, depending on age and gender, is essential for the treating physician and requires precise knowledge of the physiological development processes and the tolerable limits in all three spatial dimensions. After careful explanation to the frequently concerned parents, arestrictive approach with observation of the spontaneous course of correction on the basis of regular clinical check-ups makes sense in the majority of cases. Pathological deviations from the physiological conditions are rare overall, can be idiopathic or of secondary origin and should be further clarified diagnostically using imaging procedures. As conservative measures are ineffective, pronounced angular and/or torsional deformities of the legs requiring treatment can only be corrected by surgical intervention, even in children and adolescents. The surgical treatment modalities available are varied and differ in terms of their invasiveness and complication profile, depending on the localization, type and severity of the deformity, as well as the age and possible concomitant diseases of the affected child or adolescent.

Parity-doublet bands in the odd- A isotones U237 and Pu239 investigated by a particle-number-conserving method based on the cranked shell model

Based on the reflection-asymmetric Nilsson potential, the parity-doublet rotational bands in odd-$A$ isotones \element{237}U and \element{239}Pu have been investigated by using the particle-number-conserving (PNC) method in the framework of the cranked shell model (CSM). The experimental kinematic moments of inertia (MOIs) and angular momentum alignments are reproduced very well by the PNC-CSM calculations. The significant differences of rotational properties between \element{237}U and \element{239}Pu are explained with the contribution of nucleons occupying proton octupole-correlation pairs of $\pi ^{2} i_{13/2}f_{7/2}$. The upbendings of moments of inertia of the parity-doublet bands in \element{237}U are due to the interference terms of alignments of protons occupying $\pi f_{7/2}$ (${1/2}$) and the high-$j$ intruder $\pi i_{13/2}$ $(1/2, 3/2)$ orbitals. The splittings between the simplex partner bands of the parity-doublet bands in both \element{237}U and \element{239}Pu result from the contribution of alignment of neutron occupying the $\nu d_{5/2}$ ($1/2$) orbital.

Alternating-parity bands of U236,238 and Pu238,240 in a particle-number-conserving method based on the cranked shell model

The particle-number-conserving (PNC) method in the framework of cranked shell model (CSM) is developed to deal with the reflection-asymmetric nuclear system by applying the ${S}_{x}$ symmetry. Based on an octupole-deformed Nilsson potential, the alternating-parity bands in $^{236,238}\mathrm{U}$ and $^{238,240}\mathrm{Pu}$ are investigated. The experimental kinematic moments of inertia (MoI) and the angular momentum alignments of all studied bands are reproduced well in the PNC-CSM calculations. The striking difference of rotational behaviors between U and Pu isotopes can be linked to the strength of octupole correlations. The upbendings of the alternating-parity bands in $^{236,238}\mathrm{U}$ are due to the alignments of pairs of nucleons occupying $\ensuremath{\nu}{g}_{9/2}, \ensuremath{\pi}{f}_{7/2}$ orbitals and $\ensuremath{\nu}{j}_{15/2}, \ensuremath{\pi}{i}_{13/2}$ high-$j$ intruder orbitals. In particular, the interference terms of nucleon occupying the octupole-correlation pairs of ${\ensuremath{\nu}}^{2}{j}_{15/2}{g}_{9/2}$ and of ${\ensuremath{\pi}}^{2}{i}_{13/2}{f}_{7/2}$ give a very important contribution to the suddenly gained alignments.

Operational results on the fully automatic LHC collimator alignment

The Large Hadron Collider has a complex collimation system installed to protect its sensitive equipment from normal and abnormal beam losses. The collimators are set around the beam following a multistage transverse setting hierarchy. The insertion position of each collimator is established using beam-based alignment techniques to determine the local beam position and rms beam size at each collimator. During previous years, collimator alignments were performed semiautomatically, with collimation experts present to oversee and control the alignment. During run II, a new fully automatic alignment tool was developed and used for collimator alignments throughout 2018. This paper discusses the improvements on the alignment software to automate it using machine learning, whilst focusing on the operational results obtained when testing the new software in the LHC. The alignment tests were conducted with both proton and ion beams, and angular alignments were performed with proton beams. This upgraded software successfully decreased the alignment time by a factor of 3 and made the results more reproducible, which is particularly important when performing angular alignments.

Systematic investigation of the high- K isomers and the high-spin rotational bands in the neutron-rich Nd and Sm isotopes by a particle-number conserving method

The rotational properties of the neutron rich Nd and Sm isotopes with mass number $A\approx150$ are systematically investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the Pauli blocking effects are taken into account exactly. The 2-quasiparticle states in even-even Nd and Sm isotopes with excitation energies lower than 2.5~MeV are systematically calculated. The available data can be well reproduced and some possible 2 and 4-quasiparticle isomers are also suggested for future experiments. The experimentally observed rotational frequency variations of moments of inertia for the even-even and odd-$A$ nuclei are reproduced very well by the calculations. The effects of high-order deformation $\varepsilon_6$ on the 2-quasiparticle excitation energies and moments of inertia of the ground state bands in even-even Nd and Sm isotopes are analyzed in detail. By analyzing the occupation probability $n_\mu$ of each cranked Nilsson orbitals near the Fermi surface and the contribution of each major shell to the angular momentum alignments, the alignment mechanism in these nuclei is understood clearly.

Band crossings in 168Ta: A particle-number conserving analysis

The structures of two observed high-spin rotational bands in the doubly-odd nucleus 168Ta are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments are reproduced very well by the calculations, which confirms the configuration assignments for these two bands in previous works. The backbending and upbending mechanisms in these two bands are analyzed in detail by calculating the occupation probabilities of each orbital close to the Fermi surface and the contributions of each orbital to the total angular momentum alignments. The investigation shows that the level crossings in the first backbending is the neutron i13/2 crossing and the in second upbending is the proton h11/2 crossing.

A Millimeter-Wave Broadband <italic>in situ</italic> Alignment and Monitor System Based on Interferometric Direction-Finding Antenna

Based on the modified apertures coupling theory, this paper demonstrates a millimeter-wave broadband interferometric in situ alignment and monitor system. The numerically calculated results for the directional coupler have been validated by a comparison with the simulated ones, and the results show that the directional coupler can be applied in the interferometric systems. By nulling the difference of the power signals as well as the mixing signals from each coupler pair, spatial and angular alignments of a beam oblique incidence on the mirror can be performed, meanwhile, the power and the incident angle can be detected. Finally, the adjustment precision of the interferometric system completely meets the requirements and it is expected to be used in the active denial system and the high-power radar system.

Investigation of the high-spin rotational properties of the proton emitter 113Cs using a particle-number conserving method**Supported by National Natural Science Foundation of China (11275098, 11275248, 11505058) and Fundamental Research Funds for the Central Universities (2015QN21)

The recently observed two high-spin rotational bands in the proton emitter 113Cs are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the Pauli blocking effects are taken into account exactly. By using the configuration assignments of band 1 [π3/2+[422](g7/2), α = −1/2] and band 2 [π1/2+[420](d5/2), α = 1/2], the experimental moments of inertia and quasiparticle alignments can be reproduced much better by the present calculations than those using the configuration assginment of π1/2−[550] (h11/2), which in turn may support these configuration assignments. Furthermore, by analyzing the occupation probability nμ of each cranked Nilsson level near the Fermi surface and the contribution of each orbital to the angular momentum alignments, the backbending mechanism of these two bands is also investigated.

Redshift and luminosity evolution of the intrinsic alignments of galaxies in Horizon-AGN

Intrinsic galaxy shape and angular momentum alignments can arise in cosmological large-scale structure due to tidal interactions or galaxy formation processes. Cosmological hydrodynamical simulations have recently come of age as a tool to study these alignments and their contamination to weak gravitational lensing. We probe the redshift and luminosity evolution of intrinsic alignments in Horizon-AGN between z=0 and z=3 for galaxies with an r-band absolute magnitude of <-20. Alignments transition from being radial at low redshifts and high luminosities, dominated by the contribution of ellipticals, to being tangential at high redshift and low luminosities, where discs dominate the signal. This cannot be explained by the evolution of the fraction of ellipticals and discs alone: intrinsic evolution in the amplitude of alignments is necessary. The alignment amplitude of elliptical galaxies alone is smaller in amplitude by a factor of ~2, but has similar luminosity and redshift evolution as in current observations and in the nonlinear tidal alignment model at projected separations of > 1 Mpc. Alignments of discs are null in projection and consistent with current low redshift observations. The combination of the two populations yields an overall amplitude a factor of ~4 lower than observed alignments of luminous red galaxies with a steeper luminosity dependence. The restriction on accurate galaxy shapes implies that the galaxy population in the simulation is complete only to an r-band absolute magnitude of <-20. Higher resolution simulations will be necessary to avoid extrapolation of the intrinsic alignment predictions to the range of luminosities probed by future surveys.

Investigation of the two-quasiparticle bands in the doubly-odd nucleus 166Ta using a particle-number conserving cranked shell model

The high-spin rotational properties of two-quasiparticle bands in the doubly-odd ${}^{166}$Ta are analyzed using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency $\hbar\omega$ are reproduced very well by the particle-number conserving calculations, which provides a reliable support to the configuration assignments in previous works for these bands. The backbendings in these two-quasiparticle bands are analyzed by the calculated occupation probabilities and the contributions of each orbital to the total angular momentum alignments. The moments of inertia and alignments for the Gallagher-Moszkowski partners of these observed two-quasiparticle rotational bands are also predicted.

Is Cervical Sagittal Imbalance a Risk Factor for Adjacent Segment Pathomechanics After Multilevel Fusion?

A biomechanical study using human spine specimens. The aim of this study was to assess whether the presence of cervical sagittal imbalance is an independent risk factor for increasing the mechanical burden on discs adjacent to cervical multilevel fusions. The horizontal offset distance between the C2 plumbline and C7 vertebral body (C2-C7 Sagittal Vertical Axis (SVA)) or the angle made with vertical by a line connecting the C2 and C7 vertebral bodies (C2-C7 tilt angle) are used as radiographic measures to assess cervical sagittal balance. There is level III clinical evidence that sagittal imbalance caused by kyphotic fusions or global spinal sagittal malalignment may increase the risk of adjacent segment pathology. Thirteen human cadaveric cervical spines (Occiput-T1; age: 50.6 years; range: 21-67) were tested first in the native intact state and then after instrumentation across C4-C6 to simulate in situ two-level fusion. Specimens were tested using a previously validated experimental model that allowed measurement of spinal response to prescribed imbalance. The effects of fusion on segmental angular alignments and intradiscal pressures in the C3-C4 and C6-C7 discs, above and below the fusion, were evaluated at different magnitudes of C2-C7 tilt angle (or C2-C7 SVA). When compared with the pre-fusion state, in situ fusion across C4-C6 segments required increased flexion angulation and resulted in increased intradiscal pressure at the C6-C7 disc below the fusion in order to accommodate the same increase in C2-C7 tilt angle or C2-C7 SVA (P < 0.05). The adjacent segment mechanical burden due to fusion became greater with increasing C2-C7 tilt angle or SVA. Cervical sagittal imbalance arising from regional and/or global spinal sagittal malalignment may play a role in exacerbating adjacent segment pathomechanics after multilevel fusion and should be considered during surgical planning. N/A.

A theoretical estimate of intrinsic ellipticity bispectra induced by angular momenta alignments

Intrinsically aligned galaxy shapes are one of the most important systematics in cosmic shear measurements. So far theoretical studies of intrinsic alignments almost exclusively focus on their statistics at the two-point level. Results from numerical simulations, however, suggest that third-order measures might be even stronger affected. We therefore investigate the (angular) bispectrum of intrinsic alignments. In our fully analytical study we describe intrinsic galaxy ellipticities by a physical alignment model, which makes use of tidal torque theory. We derive expressions for the various combinations of intrinsic and gravitationally induced ellipticities, i.e. III-, GII- and GGI-alignments, and compare our results to the shear bispectrum, the GGG-term. The latter is computed using hyper-extended perturbation theory. Considering equilateral and squeezed configurations we find that for a Euclid-like survey intrinsic alignments (III-alignments) start to dominate on angular scales smaller than 20 arcmin and 13 arcmin, respectively. This sensitivity to the configuration-space geometry may allow to exploit the cosmological information contained in both the intrinsic and gravitationally induced ellipticity field. On smallest scales (l ~ 3000) III-alignments exceed the lensing signal by at least one order of magnitude. The amplitude of the GGI-alignments is the weakest. It stays below that of the shear field on all angular scales irrespective of the wave-vector configuration.

Rotational properties of the superheavy nucleus256Rf and its neighboring even-even nuclei in a particle-number-conserving cranked shell model

The ground state band was recently observed in the superheavy nucleus ${}^{256}$Rf. We study the rotational properties of ${}^{256}$Rf and its neighboring even-even nuclei by using a cranked shell model (CSM) with the pairing correlations treated by a particle-number conserving (PNC) method in which the blocking effects are taken into account exactly. The kinematic and dynamic moments of inertia of the ground state bands in these nuclei are well reproduced by the theory. The spin of the lowest observed state in ${}^{256}$Rf is determined by comparing the experimental kinematic moments of inertia with the PNC-CSM calculations and agrees with previous spin assignment. The effects of the high order deformation ${\ensuremath{\varepsilon}}_{6}$ on the angular momentum alignments and dynamic moments of inertia in these nuclei are discussed.

A study of management of fracture shaft femur in children in a rural population

Background: Femoral shaft fractures account for 1.6% of all bony injuries in children, and the mode of treatment for children between 6 and 16 years of age is still debatable. Objectives: To compare the merits and demerits of operative and conservative managements of fracture shaft femur in children in a rural population in a developing country. Materials and Methods: Forty patients in the age group of 6-14 years with transverse fractures of shaft of the femur and two different treatment protocols were selected. The patients treated in skeletal traction or fixed traction in Thomas' splint were included in one group and patients who were treated operatively with titanium elastic nails comprised the other group. Data was analyzed using Chi-square test. Results: The commonest cause of injury was motor vehicle accident, accounting for 70% of the cases, with left femur (60%) more commonly injured. All fractures in the operative group united clinically by 8 weeks and radiologically by 10 weeks, and, in the conservative group, by 9 weeks clinically and 12 weeks radiologically. The difference was statistically significant. Shortening and angular mal alignments were found more commonly in the conservative group, and the difference was significant. The follow-up for 1 year of all cases were uneventful. Conclusion: Internal fixation with titanium elastic nails provides better results than conservative treatment in traction.

Magnetic field alignment of template released ferromagnetic nanowires

A detailed investigation of magnetic field alignment of template released ferromagnetic nanowires has been undertaken. The distributions of magnetic field induced angular alignments of Ni0.8Fe0.2, Co, and Ni nanowires grown by electro-deposition and deposited onto substrates from a dilute suspension have been investigated as a function of magnetic field strengths up to ∼1 kOe. The nominal diameter of the nanowires investigated is either ∼200 nm (Ni0.8Fe0.2) or ∼300 nm (Co and Ni). The percentage of nanowires aligned within 0°–10° and 0°–20° of the applied field axis is observed to increase rapidly with increasing field strength up to ∼200 Oe, followed by a slower increase in alignment for the Ni0.8Fe0.2 and Ni wires and little improvement in alignment for the Co wires at higher fields. The proportion of aligned wires within 0°–20° is found to reach ∼82% for Ni0.8Fe0.2, ∼71% for Ni and only 53% for the Co nanowires using a magnetic field of 1 kOe. The influence of wire length upon the efficacy of magnetic alignment is investigated using Ni0.8Fe0.2 and Ni nanowires; this showed that the fractional alignment improved for longer nanowires.

Novel design and alignment of wire-grid diffraction gratings on a visible focal plane array

A pixelated, wire-grid diffraction grating is designed, fabricated, aligned, and mounted on an active focal plane array of a camera operating in the visible. The resulting design of the pixelated wire-grid polarizer array eschewed the need for fine translational alignments and drastically reduced cross-talk between pixels detecting differing polarization states. Using common optomechanical elements in conjunction with a novel correlation-based alignment metric, we are able to achieve repeatable angular alignments to better than 0.004 deg between the focal plane array and the pixelated wire-grid polarizer array, both featuring 6.45 μm pixels. An on-chip, four-state, linear snapshot polarimeter is yielded in the detailed processes and raw image data from the instrument are presented.

Perception of socket alignment perturbations in amputees with transtibial prostheses

A person with amputation's subjective perception is the only tool available to describe fit and comfort to a prosthetist. However, few studies have investigated the effect of alignment on this perception. The aim of this article is to determine whether people with amputation could perceive the alignment perturbations of their prostheses and effectively communicate them. A randomized controlled perturbation of angular (3 and 6 degrees) and translational (5 and 10 mm) alignments in the sagittal (flexion, extension, and anterior and posterior translations) and coronal (abduction, adduction, and medial and lateral translations) planes were induced from an aligned condition in 11 subjects with transtibial prostheses. The perception was evaluated when standing (static) and immediately after walking (dynamic) using software that used a visual analog scale under each alignment condition. In the coronal plane, Friedman test demonstrated general statistical differences in static (p < 0.001) and dynamic (p < 0.001) measures of perceptions with angular perturbations. In the sagittal plane, it also demonstrated general statistical differences in late-stance dynamic measures of perceptions (p < 0.001) with angular perturbations, as well as in early-stance dynamic measures of perceptions (p < 0.05) with translational perturbations. Fisher exact test suggested that people with amputation's perceptions were good indicators for coronal angle malalignments but less reliable when defining other alignment conditions.

Transport properties and model-based dynamical properties of Omani crude oils

We have measured the density and viscosity of five crude oil samples, collected from various hydrocarbon reservoirs in Oman, as functions of temperature. The measured quantities are expressed in terms of fitted formulae allowing their easy usage for different computational and simulation works. As an application, these thermo-physical data have been utilized to investigate the flow dynamics of hydrocarbon films under gravity at various temperatures. We have modeled the flow of these crude oils to study the dynamics of falling films in an open-top rectangular pipe set at various angular alignments under the assumption of Newtonian fluid describing a laminar flow. The adopted model of the investigation is not entirely novel, but the calculations aim to apply the model to various Omani crude oil samples with various American Petroleum Institute (API) values; the calculated results shed light on the dynamics of these crude oil films, which might be correlated to crude oil purification mechanism and open-top transportation.

Influence of the pairing interaction at ultrahigh spin

The pairing effect plays a very important role in nuclear phenomena. We analyze the influence of pairing interaction on angular momentum alignments and backbending frequencies near the ultrahigh spin $\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\approx}0.8$ MeV. Although the moment of inertia of rotational bands tends to be the same with or without pairing interaction, their angular momentum alignments and backbending frequencies still have large differences even at the ultrahigh spin region. For the normal orbitals, the alignment difference keeps almost constant from the larger spin region to the ultrahigh spin region. The high-$j$orbitals always cause drastic changes of alignment and lead to changes of backbending frequencies. Therefore, even at the ultrahigh spin region, to understand some nuclear phenomena, the pairing correlations should be included in some theoretical models.

The low-lying rotational bands of the neutron-rich nucleus 172Tm

The microscopic mechanism of four experimentally observed bands in 172Tm is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions. The experimental results, including the moments of inertia and angular momentum alignments of four bands in 172Tm are reproduced well by the particle-number conserving calculations. The ω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are analyzed. Other unobserved low-lying bands of 2-quansiparticles in 172Tm are predicted.