Global Rotation Research Articles

Energy transfer in compressible magnetohydrodynamic turbulence for isothermal self-gravitating fluids.

Three-dimensional, compressible, magnetohydrodynamic turbulence of an isothermal, self-gravitating fluid is analyzed using two-point statistics in the asymptotic limit of large Reynolds numbers (both kinetic and magnetic). Following an alternative formulation proposed by Banerjee and Galtier [Phys. Rev. E 93, 033120 (2016)2470-004510.1103/PhysRevE.93.033120; J. Phys. A: Math. Theor. 50, 015501 (2017)1751-811310.1088/1751-8113/50/1/015501], an exact relation has been derived for the total energy transfer. This approach results in a simpler relation expressed entirely in terms of mixed second-order structure functions. The kinetic, thermodynamic, magnetic, and gravitational contributions to the energy transfer rate can be easily separated in the present form. By construction, the new formalism includes such additional effects as global rotation, the Hall term in the induction equation, etc. The analysis shows that solid-body rotation cannot alter the energy flux rate of compressible turbulence. However, the contribution of a uniform background magnetic field to the flux is shown to be nontrivial unlike in the incompressible case. Finally, the compressible, turbulent energy flux rate does not vanish completely due to simple alignments, which leads to a zero turbulent energy flux rate in the incompressible case.

Nematic topological defects positionally controlled by geometry and external fields.

Using a Landau–de Gennes approach, we study the impact of confinement topology, geometry and external fields on the spatial positioning of nematic topological defects (TDs). In quasi two-dimensional systems we demonstrate that a confinement-enforced total topological charge of m > 1/2 decays into elementary TDs bearing a charge of m = 1/2. These assemble close to the bounding substrate to enable essentially bulk-like uniform nematic ordering in the central part of a system. This effect is reminiscent of the Faraday cavity phenomenon in electrostatics. We observe that in certain confinement geometries, varying the correlation length size of the order parameter could trigger a global rotation of an assembly of TDs. Finally, we show that an external electric field could be used to drag the boojum fingertip towards the interior of the confinement cell. Assemblies of TDs could be exploited as traps for appropriate nanoparticles, opening several opportunities for the development of functional nanodevices.

The complex kinematics of rotating star clusters in a tidal field

Abstract We broaden the investigation of the dynamical properties of tidally perturbed, rotating star clusters by relaxing the traditional assumptions of coplanarity, alignment, and synchronicity between the internal and orbital angular velocity vector of their initial conditions. We show that the interplay between the internal evolution of these systems and their interaction with the external tidal field naturally leads to the development of a number of evolutionary features in their three-dimensional velocity space, including a precession and nutation of the global rotation axis and a variation of its orientation with the distance from the cluster centre. In some cases, such a radial variation may manifest itself as a counter-rotation of the outermost regions relative to the inner ones. The projected morphology of these systems is characterized by a non-monotonic ellipticity profile and, depending on the initial inclination of the rotation axis, it may also show a twisting of the projected isodensity contours. These results provide guidance in the identification of non-trivial features which may emerge in upcoming investigations of star cluster kinematics and a dynamical framework to understand some of the complexities already hinted by recent observational studies.

Deep CNN With Multi-Scale Rotation Invariance Features for Ship Classification

With the rapid development of target tracking technology, how to efficiently take advantage of useful information from optical images for ship classification becomes a challenging problem. In this paper, a novel deep learning framework fused with low-level features is proposed. Deep convolutional neural network (CNN) has been popularly used to capture structural information and semantic context because of the ability of learning high-level features; however, lacking of capability to deal with global rotation in large-scale image and losing some important information in bottom layers of the CNN limit its performance in extracting multi-scales rotation invariance features. Comparatively, some classic algorithms, such as Gabor filter or multiple scales completed local binary patterns, can effectively capture low-level texture information. In the proposed framework, low-level features are combined with high-level features obtained by deep CNN. The fused features are further fed into a typical support vector machine classifier. The proposed strategy achieves average accuracy of 98.33% on the BCCT200-RESIZE data and 88.00% on the challenging VAIS data, which demonstrates its superior classification performance when compared with some state-of-the-art methods.

Resident & Fellow Rounds.

Neurologic care in lower- and middle-income countries is an increasing focus for the field and training of its next generation. The International Issues article features a guide for trainees seeking information on predeparture, funding, and postdeparture advice for global health rotations. The Clinical Reasoning and Teaching Image articles review the workup and management of reversible cerebral vasoconstriction syndrome, ataxia, and new-onset clonus in the setting of fever and confusion.

Wall Painting Reconstruction Using a Genetic Algorithm

Global reconstruction of two-dimensional wall paintings (frescoes) from fragments is an important problem for many archaeological sites. The goal is to find the global position and rotation for each fragment so that all fragments jointly “reconstruct” the original surface (i.e., solve the puzzle). Manual fragment placement is difficult and time-consuming, especially when fragments are irregularly shaped and uncolored. Systems have been proposed to first acquire 3D surface scans of the fragments and then use computer algorithms to solve the reconstruction problem. These systems work well for small test cases and for puzzles with distinctive features, but fail for larger reconstructions of real wall paintings with eroded and missing fragments due to the complexity of the reconstruction search space. We address the search problem with an unsupervised genetic algorithm: we evolve a pool of partial reconstructions that grow through recombination and selection over the course of generations. We introduce a novel algorithm for combining partial reconstructions that is robust to noise and outliers, and we provide a new selection procedure that balances fitness and diversity in the population. In experiments with a benchmark dataset, our algorithm is able to achieve larger and more accurate global reconstructions than previous automatic algorithms.

Spin-orbit interaction driven dimerization in one-dimensional frustrated magnets

We study the effect of spin-orbit interaction on one-dimensional U(1)-invariant frustrated magnets with dominant critical nematic fluctuations. The spin-orbit coupling explicitly breaks the U(1) symmetry of arbitrary global spin rotations about the high-symmetry axis down to $Z_2$ (invariance under a $\pi$-rotation). Given that the nematic order parameter is invariant under a $\pi$-rotation, it is relevant to ask if other discrete symmetries can be spontaneously broken. Here we demonstrate that the spin-orbit coupling induces a bond density wave that spontaneously breaks the translational symmetry and opens a gap in the excitation spectrum.

Phase transition in anisotropic holographic superfluids with arbitrary dynamical critical exponent z and hyperscaling violation factor alpha

Einstein-scalar-U(2) gauge field theory is considered in a spacetime characterized by alpha and z, which are the hyperscaling violation factor and the dynamical critical exponent, respectively. We consider a dual fluid system of such a gravity theory characterized by temperature T and chemical potential mu . It turns out that there is a superfluid phase transition where a vector order parameter appears which breaks SO(3) global rotation symmetry of the dual fluid system when the chemical potential becomes a certain critical value. To study this system for arbitrary z and alpha , we first apply Sturm–Liouville theory and estimate the upper bounds of the critical values of the chemical potential. We also employ a numerical method in the ranges of 1 le z le 4 and 0 le alpha le 4 to check if the Sturm–Liouville method correctly estimates the critical values of the chemical potential. It turns out that the two methods are agreed within 10 percent error ranges. Finally, we compute free energy density of the dual fluid by using its gravity dual and check if the system shows phase transition at the critical values of the chemical potential mu _mathrm{c} for the given parameter region of alpha and z. Interestingly, it is observed that the anisotropic phase is more favored than the isotropic phase for relatively small values of z and alpha . However, for large values of z and alpha , the anisotropic phase is not favored.

Multiple rotation symmetry group detection via saliency-based visual attention and Frieze expansion pattern

Global maximum symmetry center probability-based rotation symmetry detection methods are unable to identify small-scale rotation symmetry centers in real-world images and come with a costly computational burden. This paper presents a novel strategy comprised of multiple-local-region searching in the whole image and multiple-model computation to map rotation symmetry strength (RSS) in the local region. The multiple-local-region searching method creates local regions in which the global maximum symmetry center detection method changes to a local maximum symmetry center detection method. In the local region, the multiple-model computation efficiently detects regular, small-scale, and skewed symmetry centers. This strategy improves the detection ability for regular, small-scale, and skewed rotation symmetry centers while minimizing the complexity of the algorithm based on a rotation symmetry strength (RSS) map and symmetry shape density (SSD) map. Experimental results indicate that this strategy not only allows more rotation symmetry centers to be identified successfully, but is simpler than traditional strategies as it only employs RSS maps.

Time course of changes in left ventricular twist in the presence of idiopathic left bundle branch block during exercise testing

To investigate left ventricular (LV) deformation properties, rotation, and twist during a bicycle ergometer exercise test among patients with idiopathic left bundle branch block (LBBB). Thirty-four patients with idiopathic LBBB having a mean QRS duration of 153±24 msec were examined. A control group included 18 apparently healthy volunteers. All the patients and apparently healthy individuals underwent echocardiography to determine LV hemodynamic parameters, deformity, rotation and twist at rest and after exercise test. As compared with the control, the idiopathic LBBB group at rest showed decreases in LV global longitudinal deformity (-15.6±4.7 and -18.4±3.1%, respectively; p=0.037), apical rotation (4.59±4.2° and 8.99±3.68°; p=0.0067) and twist (9.08±4.59° and 13.96±4.61°; p=0.0156), whereas there were no differences in LV ejection fraction and end-systolic and end-diastolic volumes. After exercise testing there were no augmentations in basal and apical rotation and resulting ΔTwist in the idiopathic LBBB group compared with the control (-2.05±8.35 and 4.66±8.49%; p=0.0463). The described changes in LV rotation and twist during exercise testing occurred in the presence of elevated pulmonary artery systolic pressure (PASP) in the LBBB group compared with the control (41.6±3.81 and 32.4±3.81 mm Hg, respectively; p=0.0201). Decreases in LV basal, apical and resulting twist may lead to elevated PASP in patients with idiopathic LBBB during exercise.

Stability of interlinked neutron vortex and proton flux tube arrays in a neutron star: equilibrium configurations

Three-dimensional, Gross-Pitaevskii equation (GPE) simulations are presented of the interaction between neutron superfluid vortices and proton superconductor flux tubes in a rotating, harmonic trap, representing an idealised model of the outer core of a neutron star. Low-energy states of the neutron condensate are calculated by evolving the GPE in imaginary time in the presence of a prescribed, static, rectilinear flux tube array. The calculations are carried out as a function of the angle between the global magnetic and rotation axes, and the amplitude and sign of the current-current and density couplings between the neutron and proton condensates. It is found that the system is frustrated by the competition between vortex-vortex repulsion and vortex-flux-tube attraction (pinning), leading to the formation of vortex tangles and "glassy" behaviour characterized by multiple metastable states spaced closely in energy. The dimensionless parameters in the simulations are ordered as one expects in a neutron star, but the dynamic range is many orders of magnitude smaller than in reality, so caution must be exercised when assessing the astrophysical implications. Nevertheless the results suggest that tangled vorticity may be endemic in neutron star outer cores.

Head and trunk 3D orientation during heading and pointing tasks

Both heading and pointing tasks may affect head and trunk since head rotation contributes to orient the gaze and trunk rotation participates to arm movement. The aim of the present study is to evaluate head and trunk 3D orientation during heading and pointing tasks. Right arm pointing and heading tasks toward eight visual targets placed in a wide frontal workspace were studied in ten healthy, right handed subjects. Three-dimensional orientation of the head and trunk (flexion-extension, lateral bending and axial rotation) and upper arm were measured using an electromagnetic tracking system. For both heading and pointing tasks, the orientation of the head in space was closely related to the target with a coupling between rotation and contralateral bending. The trunk was stable during heading but showed large leftward axial rotation during pointing as a function of target direction, coupled with right head rotation relative to the trunk. Our results suggest that the global rotations within the cervical spine compensated for trunk rotation in order to maintain an adapted orientation of the head toward the visual target. In the future, this should be taken into account for the prevention and the rehabilitation of musculoskeletal disorders.

Coalition for Global Clinical Surgical Education: The Alliance for Global Clinical Training

Assessment of the effect of the collaborative relationship between the high-income country (HIC) surgical educators of the Alliance for Global Clinical Training (Alliance) and the low-income country surgical educators at the Muhimbili University of Health and Allied Sciences/Muhimbili National Hospital (MUHAS/MNH), Dar Es Salaam, Tanzania, on the clinical global surgery training of the HIC surgical residents participating in the program. A retrospective qualitative analysis of Alliance volunteer HIC faculty and residents' reports, volunteer case lists and the reports of Alliance academic contributions to MUHAS/MNH from 2012 to 2017. In addition, a survey was circulated in late 2016 to all the residents who participated in the program since its inception. Twelve HIC surgical educators provided rotating 1-month teaching coverage at MUHAS/MNH between academic years 2012 and 2017 for a total of 21 months. During the same time period 11 HIC residents accompanied the HIC faculty for 1-month rotations. HIC surgery residents joined the MUHAS/MNH Department of Surgery, made significant teaching contributions, performed a wide spectrum of "open procedures" including hand-sewn intestinal anastomoses. Most had had either no or limited previous exposure to hand-sewn anastomoses. All of the residents commented that this was a maturing and challenging clinical rotation due to the complexity of the cases, the limited resources available and the ethical and emotional challenges of dealing with preventable complications and death in a resource constrained environment. The Alliance provides an effective clinical global surgery rotation at MUHAS/MNH for HIC Surgery Departments wishing to provide such an opportunity for their residents and faculty.

Global rotation of mechanical metamaterials induced by their internal deformation

In this work, we propose the concept that a device based on mechanical metamaterials can be used to induce and control its own rotational motion as a result of internal deformations due to the conversion of translational degrees of freedom into rotational ones. The application of a linear force on the structural units of the system may be fine-tuned in order to obtain a desired type of rotation. In particular, we show, how it is possible to maximise the extent of rotation of the system through the alteration of the geometry of the system. We also show how a device based on this concept can be connected to an external body in order to rotate it which result may potentially prove to be very important in the case of applications such as telescopes employed in space.

On Becoming a Global Citizen: Transformative Learning Through Global Health Experiences

BackgroundGlobalization has increased the demand for international experiences in medical education. International experiences improve medical knowledge, clinical skills, and self-development; influence career objectives; and provide insights on ethical and societal issues. However, global health rotations can end up being no more than tourism if not structured to foster personal transformation and global citizenship. ObjectiveWe conducted a qualitative assessment of trainee-reported critical incidents to more deeply understand the impact of our global health experience on trainees. MethodsA cross-sectional survey was administered to trainees who had participated in a 2-month elective in Kenya from January 1989 to May 2013. We report the results of a qualitative assessment of the critical incident reflections participants (n = 137) entered in response to the prompt, “Write about one of your most memorable experiences and explain why you chose to describe this particular one.” Qualitative analyses were conducted using thematic analysis and crystallization immersion analytic methods based on the principles of grounded theory, employing a constructivists' research paradigm. FindingsFour major themes emerged. These themes were Opening Oneself to a Broader World View; Impact of Suffering and Death; Life-Changing Experiences; and Commitment to Care for the Medically Underserved. ConclusionsCircumstances that learners encounter in the resource-scarce environment in Kenya are eye-opening and life-changing. When exposed to these frame-shifting circumstances, students elaborate on or transform existing points of view. These emotionally disruptive experiences in an international health setting allowed students to enter a transformational learning process with a global mind. Students can see the world as an interdependent society and develop the capacity to advance both their enlightened self-interest and the interest of people elsewhere in the world as they mature as global citizens. Medical schools are encouraged to foster these experiences by finding ways to integrate them into curriculum.

Increased apical rotation in patients with severe aortic stenosis assessed by three-dimensional speckle tracking imaging.

Two-dimensional (2D) speckle tracking imaging (STI) is a non-invasive method used to assess subtle changes in left ventricular (LV) function such as strain and rotational dynamics. However, 2D methodology is complicated by issues such as the out-of-plane problem inherent in short-axis imaging. In addition, circumferential rotation contributes to three-dimensional (3D) wall deformations and affects tracking accuracy. By using 3D-STI technique, we evaluated LV global longitudinal strain (GLS) and apical rotation in severe aortic stenosis (AS) patients with preserved LV ejection fraction (EF). LV GLS and apical rotation were evaluated using 3D-STI in 20 severe AS patients (79±8years old; aortic valve area 0.7±0.2cm2) with preserved LVEF (68±7%). Data were compared with those of 11 hypertensive LV hypertrophy (LVH) patients (75±10years old, EF=66±4%) and 12 controls (healthy individuals: 30±14years old, EF=63±6%). Compared with LVH patients, severe AS patients had significantly decreased values of GLS (-13.0±2.4 vs. -10.4±2.0%, p=0.008). In contrast, LV rotation was significantly higher in AS than LVH patients (13.9 ±3.0° vs. 10.8 ±2.5°, p=0.007). There was no significant difference in stroke volume index among three groups. In these three groups, severe AS patients had significantly decreased values of GLS [analysis of variance (ANOVA), p<0.001] and increased LV rotation (ANOVA, p<0.001). In severe AS patients, impaired GLS existed although LVEF was preserved. However, LV rotation was increased in patients with severe AS probably to maintain the LV stroke volume.

Mean mass transport in an orbitally shaken cylindrical container

A cylindrical container partially filled with a liquid in orbital shaking motion, i.e. in circular translation with fixed orientation with respect to an inertial frame of reference, generates, along with a rotating sloshing wave, a mean flow rotating in the same direction as the wave. Here we investigate experimentally the structure and the scaling of the wave flow and the Lagrangian mean flow in the weakly nonlinear regime, for small forcing amplitude and for forcing frequency far from the resonance, using conventional and stroboscopic particle image velocimetry. The Lagrangian mean flow is composed of a strong global rotation near the center and a non trivial pattern of poloidal recirculation vortices of weaker amplitude, mostly active near the contact line. The global rotation near the center is robust with respect to changes in viscosity and forcing frequency, and its amplitude compares well with the predicted Stokes drift for an inviscid rotating sloshing wave. On the other hand, the spatial structure of the poloidal vortices show strong variation with viscosity and forcing frequency, suggesting that it results from the streaming flow driven by the complex oscillatory boundary layers near the contact line.

Solar cycle variations of rotation and asphericity in the near-surface shear layer

The precise shape of the Sun is sensitive to the influence of gravity, differential rotation, local turbulence and magnetic fields. So its precise measurement is a long-standing astrometric objective. It has been previously shown by different methods that the solar shape exhibits asphericity that evolves with the solar cycle. Thanks to the Michelson Doppler Imager (MDI) on Solar and Heliospheric Observatory (SoHO) and the Helioseismic and Magnetic Imager (HMI) aboard NASA's Solar Dynamics Observatory (SDO), and their capability to observe with an unprecedented accuracy the surface gravity oscillation (f) modes, it is possible to extract information concerning the coefficients of rotational frequency splitting, a1, a3 and a5, that measure the latitudinal differential rotation, together with the a2, a4 and a6 asphericity coefficients. Analysis of these helioseismology data with time for almost two solar cycles, from 1996 to 2017, reveals a close correlation of the a1 and a5 coefficients with the solar activity, whilst a3 exhibits a long-term trend and a weak correlation with the solar activity in the current solar cycle indicating a substantial change of the global solar rotation, potentially associated with a long-term evolution of the solar cycles. Looking in more details, the asphericity coefficients, a2, a4 and a6 are more strongly associated with the solar cycle when applying a time lag of respectively 0.1, 1.6 and −1.6 years. The magnitude of a6-coefficient varies in phase with the sunspot number (SN), but its amplitude is ahead of the SN variation. The latest measurements made in mid 2017 indicate that the magnitude of the a6-coefficient has probably reached its minimum; therefore, the next solar minimum can be expected by the end of 2018 or in the beginning of 2019. The so-called “seismic radius” in the range of f-mode angular degree: ℓ=137−299 exhibits a temporal variability in anti-phase with the solar activity; its relative value decreased by ∼2.3×10−5 in Solar Cycle 23 and ∼1.7×10−5 in Cycle 24. Such results will be useful for better understanding the physical mechanisms which act inside the Sun, and so, better constrain dynamo models for forecasting the solar cycles.

Left ventricular longitudinal function assessment in rabbits after acute occlusion of left anterior descending coronary artery by two-dimensional speckle tracking imaging

AbstactBackgroundTo evaluate the left ventricular (LV) longitudinal function changes in rabbits after acute occlusion of the left anterior descending artery (LAD) by two-dimensional speckle tracking imaging (2D–STI).MethodsForty-eight New Zealand white rabbits underwent echocardiography examination. EchoPAC was used to measure LV peak systolic longitudinal strain (LS) of the endocardium, middle myocardium, and epicardium, peak longitudinal strain rate (LSr), segmental and global longitudinal rotation (LR) degrees. Ligated the LAD and repeated all measurements after 10 min.ResultsPeak LS and LSr were significantly different between the preoperative and postoperative rabbits among most LV walls (P < 0.05). In apical four-chamber view, there was significant difference in the degrees of rotation of the LV lateral wall in preoperative and postoperative rabbits (P < 0.05). In apical three-chamber view, the rotation degrees of the posterior wall and the LR were significantly lower in the postoperative than in the preoperative (P < 0.001). In apical two-chamber view, the rotation degrees of the inferior wall and the LR were significantly lower in the postoperative (P < 0.05).ConclusionsLeft ventricular function was impaired after acute occlusion of LAD. Segmental rotational degrees and changes in LR could be useful indicators of cardiac function during the early phases of acute myocardial ischemia.

Longitudinal rotation: a new way to detect the cardiotoxicity of anthracycline-based chemotherapy in breast cancer patients

Background and aimsThe study was to compare cardiac parameters before and after anthracycline-based chemotherapy and identify a parameter for detecting cardiotoxicity in breast cancer patients.MethodsCardiac function in 43 female breast cancer patients was evaluated at three time points: baseline, 1-3 days before the initiation of anthracycline-based chemotherapy; 3 weeks and 6 months after the final cycle of chemotherapy. At each visit, the peak longitudinal velocity; strain rate; peak systolic strain; peak systolic longitudinal displacement, and segmental and global longitudinal rotation degrees of the left ventricular were measured.ResultsThe peak early-diastole left ventricular wall velocity at baseline was significantly higher than the values at 3 weeks and 6 months after the final cycle of chemotherapy. The absolute value of the lateral wall peak systolic longitudinal rotation degrees was significantly higher at baseline than at 3 weeks and 6 months after the final cycle of chemotherapy, whereas the absolute value of the global peak systolic longitudinal rotation degrees at baseline was significantly lower than the values at 3 weeks and 6 months after the final cycle of chemotherapy. None of the measured parameters differed significantly between the 3 weeks and 6 months after the final cycle of chemotherapy.ConclusionsCardiac diastolic and systolic dysfunction was found after anthracycline-based chemotherapy in this study, and the peak systolic longitudinal rotation degrees can be used to detect dysfunction after chemotherapy. The cardiotoxicity of epirubicin-based chemotherapy is stronger than that of therarubicin-based chemotherapy.