Relative Phase Research Articles

Lumbopelvic movement coordination during walking improves with transfemoral bone anchored limbs: Implications for low back pain

BackgroundLow back pain (LBP) is more prevalent in patients with transfemoral amputation using socket prostheses than able-bodied individuals, in part due to altered spinal loading caused by aberrant lumbopelvic movement patterns. Early evidence surrounding bone-anchored limb functional outcomes is promising, yet it remains unknown if this novel prosthesis influences LBP or movement patterns known to increase its risk. Research questionHow are self-reported measures of LBP and lumbopelvic movement coordination patterns altered when using a unilateral transfemoral bone-anchored limb compared to a socket prosthesis? MethodsFourteen patients with unilateral transfemoral amputation scheduled to undergo intramedullary hardware implantation for bone-anchored limbs due to failed socket use were enrolled in this longitudinal observational cohort study (7 F/7 M, Age: 50.2±12.0 years). The modified Oswestry Disability Index (mODI) (self-reported questionnaire) and whole-body motion capture during overground walking were collected before (with socket prosthesis) and 12-months following bone-anchored limb implantation. Lumbopelvic total range of motion (ROM) and continuous relative phase (CRP) segment angles were calculated during 10 bilateral gait cycles. mODI, total ROM, CRP and CRP variabilities were compared between time points. ResultsmODI scores were significantly reduced 12-months after intramedullary hardware implantation for the bone-anchored limb (P = 0.013). Sagittal plane trunk and pelvis total ROM during gait were reduced after implantation (P = 0.001 and P < 0.001, respectively). CRP values were increased (more anti-phase) in the sagittal plane during single limb stance and reduced (more in-phase) in the transverse plane during pre-swing of the amputated limb gait cycle (P << 0.001 and P = 0.029, respectively). No differences in CRP values were found in the frontal plane. SignificanceDecreases in mODI scores and lumbopelvic ROM, paired with the changes in lumbopelvic coordination, indicate that bone-anchored limbs may reduce LBP symptoms and reduce compensatory movement patterns for people with unilateral transfemoral amputation.

Asbestos Bodies in Human Lung: Localization of Iron and Carbon in the Coating

Asbestos is a term that includes six fibrous mineral phases related to different lung diseases, including asbestosis, lung cancer, and Malignant Pleural Mesothelioma (MPM). Since the last century, these minerals have been widely studied under their mineralogical/chemical and physical aspects with in vivo and in vitro studies to understand the mechanisms of their carcinogenicity. There are several techniques described in the literature, as optical and electron microscopies, for the identification of coated (asbestos bodies, ABs) and uncoated fibers, but only micro-Raman spectroscopy permits a sure characterization of these minerals—and of the related phases—directly in the histological sections of pulmonary parenchyma without any manipulation. In this case, the risk of the loss of associated inorganic phases from asbestos bodies (ABs) and fibers (e.g.: iron or carbonaceous micro-particles) is avoided. Asbestos bodies are produced by the activity of alveolar macrophages with degradation/inactivation of asbestos fibers. Inside the alveolar macrophages, organic and inorganic material settles on the foreign fibers forming an iron-rich proteic and carbonaceous coating. In this study, Variable Pressure Scanning Electron Microscopy with annexed Electron Dispersive Spectroscopy (VP-SEM/EDS) and micro-Raman spectroscopy were applied to the characterization of the phases in the ABs. Characterization of carbonaceous materials (CMs), observed in pristine asbestos phases in previous works, was therefore performed, addressing the micro-Raman laser beam on different points of the asbestos bodies, and Raman mappings on ABs were carried out for the first time. Coupling the data obtained by VP-SEM/EDS and micro-Raman spectroscopy, it was possible to collect information about the iron and carbonaceous phases adhered to the fibers, probably lost during the classical tissue digestion procedures. Information about both mineral and carbonaceous components might be useful to understand the whole structure of “asbestos bodies” and the inflammogenic and carcinogenic effects of the asbestos phases coupled to CMs, that might derive from cigarette smoke or from environmental pollution; this study might be useful to deepen also the possible detrimental role of ABs in the tissues.

Refinement of the uranium dispersion corrections from anomalous diffraction

The evolution of the uranium chemical state in uranium compounds, principally in the oxides, is of concern in the context of nuclear fuel degradation under storage and repository conditions, and in accident scenarios. The U–O system shows complicated phase relations between single-valence uranium dioxide (UO2) and different mixed-valence compounds (e.g. U4O9, U3O7 and U3O8). To try resolving the electronic structure associated with unique atomic positions, a combined application of diffraction and spectroscopic techniques, such as diffraction anomalous fine structure (DAFS), can be considered. Reported here is the application of two newly developed routines for assessing a DAFS data set, with the aim of refining the uranium X-ray dispersion corrections. High-resolution anomalous diffraction data were acquired from polycrystalline powder samples of UO2 (containing tetravalent uranium) and potassium uranate (KUO3, containing pentavalent uranium) using synchrotron radiation in the vicinity of the U L 3 edge (17.17 keV). Both routines are based on an iterative refinement of the dispersion corrections, but they differ in either using the intensity of a selection of reflections or doing a full-pattern (Rietveld method) refinement. The uranium dispersion corrections obtained using either method are in excellent agreement with each other, and they show in great detail the chemical shifts and differences in fine structure expected for tetravalent and pentavalent uranium. This approach may open new possibilities for the assessment of other, more complicated, materials such as mixed-valence compounds. Additionally, the DAFS methodology can offer a significant resource optimization because each data set contains both structural (diffraction) and chemical (spectroscopy) information, which can avoid the requirement to use multiple experimental stations at synchrotron sources.

Determination of the Σ^{+} Timelike Electromagnetic Form Factors.

Based on data samples collected with the BESIII detector at the BEPCII collider, the process e^{+}e^{-}→Σ^{+}Σ[over ¯]^{-} is studied at center-of-mass energies sqrt[s]=2.3960, 2.6454, and 2.9000GeV. Using a fully differential angular description of the final state particles, both the relative magnitude and phase information of the Σ^{+} electromagnetic form factors in the timelike region are extracted. The relative phase between the electric and magnetic form factors is determined to be sinΔΦ=-0.67±0.29(stat)±0.18(syst) at sqrt[s]=2.3960 GeV, ΔΦ=55°±19°(stat)±14°(syst) at sqrt[s]=2.6454 GeV, and 78°±22°(stat)±9°(syst) at sqrt[s]=2.9000 GeV. For the first time, the phase of the hyperon electromagnetic form factors is explored in a wide range of four-momentum transfer. The evolution of the phase along with four-momentum transfer is an important input for understanding its asymptotic behavior and the dynamics of baryons.

Coherent control of photonic band gaps through the relative phase using modified superradiance lattice.

We report photonic band gaps based on a modified superradiance lattice having reflectivity close to 100% for both the low and high-frequency ranges. We observe that tuning the relative phase between the coupling fields provides additional control over photonic band gaps. We notice that the relative phase can control three input channels of the probe field simultaneously and efficiently. This feature of relative phase over photonic band gaps provides potential in the field of quantum optics. Further, this scheme is experimentally more viable. Rubidium atoms 87Rb can obtain low-frequency (infrared) photonic band gaps. On the other hand, rubidium atoms 85Rb and beryllium ions Be2+ can form high-frequency ultraviolet and soft X-ray photonic band gaps, achieving reflectivities of 80% and 96%, respectively. This scheme holds promise for constructing highly efficient optical switches and beam splitters.

Effects of running skill and speed on limb coordination during submaximal and maximal sprinting

In locomotion, the relative phasing of the limbs changes with speed and provides valuable insight to neuromuscular control of gait. At present, it is unknown if individuals trained in sprinting coordinate their limbs differently than runners from other athletic backgrounds. Therefore, we aimed to characterize the effects of speed and skill on lower limb coordination. Twenty-five physically active (PA) and fifteen track and field (TF) athletes performed 40 m running trials at self-selected speeds, from jogging to maximal sprinting. We measured lower limb kinematics during steady-speed running, and quantified coordination using continuous relative phase (CRP) methods for interlimb pairs (Thigh-Thigh, Shank-Shank) and intralimb pairs (Shank-Thigh). Regression techniques showed between-group differences in scaling of coordination with speed during the stance phase, such that coordination was significantly more antiphase during jogging and running speeds in TF. During flight the scaling between groups was similar, but there were persistent and significant differences in coordination across all speeds. Comparing only the maximal speed trials, we found interlimb coordination was significantly more antiphase for TF in both stance and flight. In all cases, Shank-Shank coordination showed the largest between-group differences. Our results demonstrate the importance of interlimb coordination at maximal sprint speed, particularly during the flight phase and between shank segments. Between-group differences in coordination at slower speeds suggest a selective tuning of coordination in trained runners. We speculate differences in limb coordination are due to acquired motor patterns from optimizing forward velocity and its mechanical determinants, which differ particularly during flight/swing and between shank segments.

PHASE RELATIONS IN THE Bi2-Bi2Se3-Bi2Te3 SYSTEM AND CHARACTERIZATION OF SOLID SOLUTIONS

Phase relations in the Bi2–Bi2Se3–Bi2Te3 system were determined experimentally using differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Based on the experimental results, a solid-phase equilibria diagram at room temperature, a projection of the liquidus surface, and several polythermal sections of the phase diagram were constructed. The regions of primary crystallization and phase homogeneity, types, and coordinates of non- and monovariant equilibria were determined. Continuous solid solutions along the Bi8Se9–Bi8Te9, BiSe–BiTe, and Bi4Se3–Bi4Te3 sections, as well as wide areas of solid solutions based on other bismuth selenides and tellurides, were found. The established phase diagrams can be used for the synthesis of solid solutions of a given composition and the growth of their single crystals by directional crystallization from solution-melts

Controlling the polarization structure of vector beams synthesized by a fiber laser array

In our earlier paper [Adamov, E. V., Aksenov, V. P., Dudorov, V. V., Kolosov, V. V., & Levitskii, M. E. (2022). Controlling the spatial structure of vector beams synthesized by a fiber laser array. Optics & Laser Technology, 154, 108,351], we presented the method to control the spatial intensity distribution of a beam synthesized as a result of coherent combining of subbeams from an array of phase-controlled fiber radiation sources, each subbeam characterized by its own direction of linear polarization. In this paper, we consider theoretically and experimentally the feasibility of controlling the polarization structure of such synthesized beams by changing the phase relations between individual subbeams. It is shown that for fixed polarization directions of the subbeams, the nonuniform polarization distribution of the synthesized beam, whose character depends on the phase relations and polarization directions of the subbeams, can be controlled via a change of only subbeam phases.

Reversal of heat flow and extraction of work by means of initial correlations within open quantum systems

We explore the impact of initial correlations within an open quantum system on the thermodynamic process. The system of interest consists of two interacting subsystems, each embedded in a thermal reservoir. Our findings reveal that when there are initial correlations between the subsystems, heat can be transferred from the colder body to the hotter one or accelerated to flow from the hotter body to the colder one. This is made possible by selecting the appropriate relative phase of the system's correlated state. Moreover, the correlated system can act as a refrigerator or an accelerator while simultaneously performing work on an external agent. We also extend our study to a multipartite system, where we demonstrate that the accumulation of correlations in the system can enhance the reversed heat, the work, and the reversal duration.

A consistent map in the medial entorhinal cortex supports spatial memory

The medial entorhinal cortex (MEC) is hypothesized to function as a cognitive map for memory-guided navigation. How this map develops during learning and influences memory remains unclear. By imaging MEC calcium dynamics while mice successfully learned a novel virtual environment over ten days, we discovered that the dynamics gradually became more spatially consistent and then stabilized. Additionally, grid cells in the MEC not only exhibited improved spatial tuning consistency, but also maintained stable phase relationships, suggesting a network mechanism involving synaptic plasticity and rigid recurrent connectivity to shape grid cell activity during learning. Increased c-Fos expression in the MEC in novel environments further supports the induction of synaptic plasticity. Unsuccessful learning lacked these activity features, indicating that a consistent map is specific for effective spatial memory. Finally, optogenetically disrupting spatial consistency of the map impaired memory-guided navigation in a well-learned environment. Thus, we demonstrate that the establishment of a spatially consistent MEC map across learning both correlates with, and is necessary for, successful spatial memory.

Fostering teacher agency in school‐based climate change education in England, UK

AbstractDrawing on conceptualisations of teacher agency through the ecological approach, and in the context of recent policy activity, we explored primary and secondary school teachers' experiences of agency in relation to climate change education in England. Data collection occurred over two distinct but related phases. Firstly, we completed a series of interviews with the same three secondary geography teachers at the outset of their careers (15 interviews during 2020–2022) which included 1 year of Initial Teacher Education and 2 years as Early Career Teachers (ECTs). Secondly, we captured the experiences of further 24 in‐service science and geography teachers (with expertise beyond the ECT period) through two online workshops held in November 2022, the first for primary teachers (n = 10) and the second for secondary teachers (n = 10). Interviews were held with four teachers (two primary and two secondary) who could not attend the workshops (n = 4). Our findings underline the importance of structures (e.g. school leadership) and culture (e.g. ideas and values) in fostering teacher agency. Teachers across primary and secondary phases and at different career stages highlighted the value of curricular and extra‐curricular spaces for climate change education. If all children and young people are to access effective climate change education, researchers and policy makers will need to further consider ways to ensure teachers can achieve agency, including through access to transformative professional learning which fosters agency in relation to climate change education.

Recent advances of rare earth iron garnet magneto-optical single crystals

R3Fe5O12 (RIG) crystals are the most desirable elements for magneto-optical isolators in the near-infrared (NIR) to mid-infrared (MIR) region, with ever-growing demands for optical fiber communication and high-power laser system. Now, this system is the only commercialized Faraday rotator for optical isolators in 5G wireless communications. However, the growth of high-quality bulk RIG single crystals has been a big challenge for a long time, due to the typical incongruent melting characteristic and complex phase relationships. This work comprehensively summarizes the recent advances for the growth of RIG single crystals, including the proper choice of flux and innovative strategies on several growth techniques, like the flux-Bridgman, edge-defined film-fed growth (EFG) and top seeded solution growth (TSSG), etc. Effective modulation on the optical and magneto-optical performance is highlighted. Some ongoing perspectives are also proposed and discussed. It is anticipated that this work will provide deeper insight into the exploration of high-performance magneto-optical crystals for potential applications in NIR-MIR wavelength.

Stabilizing Fabry-Perot optical frequency comb with differential phase detection and bias compensation.

We present a stable optical frequency comb (OFC) that utilizes a Fabry-Perot phase modulator. The environmental-induced state variation of the OFC is accurately detected by measuring the relative phase changes of beat signals from its upper and lower sidebands. We then compensate for this variation by controlling OFC bias voltage through a homodyne phase-locked loop. The differential phase detection eliminates the common-mode detection noise, enabling long-term stability of the OFC without requiring any additional reference signal. The relative phase change is only 0.056° over 3800 s. Even under a drastic temperature change, the OFC remains stable, validating the effectiveness of the proposed stabilization method.

Taxonomy of hybridly polarized Stokes vortex beams.

Structured beams carrying topological defects, namely phase and Stokes singularities, have gained extensive interest in numerous areas of optics. The non-separable spin and orbital angular momentum states of hybridly polarized Stokes singular beams provide additional freedom for manipulating optical fields. However, the characterization of hybridly polarized Stokes vortex beams remains challenging owing to the degeneracy associated with the complex polarization structures of these beams. In addition, experimental noise factors such as relative phase, amplitude, and polarization difference together with beam fluctuations add to the perplexity in the identification process. Here, we present a generalized diffraction-based Stokes polarimetry approach assisted with deep learning for efficient identification of Stokes singular beams. A total of 15 classes of beams are considered based on the type of Stokes singularity and their associated mode indices. The resultant total and polarization component intensities of Stokes singular beams after diffraction through a triangular aperture are exploited by the deep neural network to recognize these beams. Our approach presents a classification accuracy of 98.67% for 15 types of Stokes singular beams that comprise several degenerate cases. The present study illustrates the potential of diffraction of the Stokes singular beam with polarization transformation, modeling of experimental noise factors, and a deep learning framework for characterizing hybridly polarized beams.

Exposure Time Control Method for Higher Intermediate Frequency in Optical Heterodyne Imaging and Its Application to Electric-Field Imaging Based on Electro-Optic Effect.

We propose and demonstrate a method for equivalent time sampling using image sensors to selectively detect only the target frequency. Shortening the exposure time of the image sensor and using equivalent time sampling allows for the detection of frequency components that are higher than the frame rate. However, the imaging system in our previous work was also sensitive to the frequency component at 1/4 of the frame rate. In this study, we control the phase relationship between the exposure time and observed signal by inserting an additional interval once every four frames to detect the target frequency selectively. With this technique, we conducted electric field imaging based on the electro-optic effect under high noise conditions in the low-frequency band to which the conventional method is sensitive. The results demonstrated that the proposed method improved the signal-to-noise ratio.

Spatially varying optical characteristics in quantum-dot molecules through interdot tunneling

In this paper, we investigate the spatially dependent absorption characteristics in structurally asymmetric quantum-dot molecules (QDMs), characterized by four energy levels interacting with position-dependent beams and varying system parameters. We explore the effects of detuning, standing wave intensity, and the relative phase of applied fields on the absorption patterns within the medium. A diverse array of patterns emerges, including cross-like structures, ring-like formations, and localized absorption maxima, illustrating the intricate interplay between these parameters and the spatial distribution of absorption features. The introduction of a vortex-shaped control field adds a new dimension to the study, revealing azimuthal dependence and providing a novel perspective for manipulating absorption and gain properties based on the orbital angular momentum of the control field. This work contributes to a comprehensive understanding of the intricate dynamics governing spatially dependent absorption in QDMs, offering valuable insights for controlled manipulation and practical applications in quantum systems.

A phase-shifting anterior-posterior network organizes global phase relations.

Prior research has identified a variety of task-dependent networks that form through inter-regional phase-locking of oscillatory activity that are neural correlates of specific behaviors. Despite ample knowledge of task-specific functional networks, general rules governing global phase relations have not been investigated. To discover such general rules, we focused on phase modularity, measured as the degree to which global phase relations in EEG comprised distinct synchronized clusters interacting with one another at large phase lags. Synchronized clusters were detected with a standard community-detection algorithm, and the degree of phase modularity was quantified by the index q. Notably, we found that the mechanism controlling phase modularity is remarkably simple. A network comprising anterior-posterior long-distance connectivity coherently shifted phase relations from low-angles (|Δθ| < π/4) in low-modularity states (bottom 5% in q) to high-angles (|Δθ| > 3π/4) in high-modularity states (top 5% in q), accounting for fluctuations in phase modularity. This anterior-posterior network may play a fundamental functional role as (1) it controls phase modularity across a broad range of frequencies (3-50 Hz examined) in different behavioral conditions (resting with the eyes closed or watching a silent nature video) and (2) neural interactions (measured as power correlations) in beta-to-gamma bands were consistently elevated in high-modularity states. These results may motivate future investigations into the functional roles of phase modularity as well as the anterior-posterior network that controls it.

Elastic and piezoelectric properties of β-glycine - a quantum crystallography view on intermolecular interactions and a high-pressure phase transition.

The effect of hydrostatic compression on the elastic and electronic properties of β-glycine was studied using a quantum crystallography approach. The interrelations between the changes in the microscopic quantum pressure in the electronic continuum, macroscopic compressibility and piezoelectricity were considered. The geometries and energies of hydrogen bonds in the crystal structure of β-glycine were considered as functions of pressure before and after a phase transition into the β'-phase in relation to the mechanism of this phase transition.

Phase diagram study of Na2O–ThO2–P2O5 system and investigation of thermo physical properties of quaternary compounds

The subsolidus phase relations in Na2O–ThO2–P2O5 pseudo ternary system were determined at 1223 K. Synthesis of all the phases, used for drawing phase diagram, was carried out by solid state route. Formation of ternary and quaternary compounds in Na2O–ThO2, Na2O–P2O5, ThO2–P2O5 and Na2O–ThO2–P2O5 systems was confirmed at 1223 K. With the help of these compounds and phase analysis of number of synthetic mixtures, prepared by reacting different mol fractions of Na2O, ThO2 and P2O5 at 1223 K, phase diagram was drawn and phase boundaries were established. No ternary compound was identified in Na2O–ThO2 system. Formation of three quaternary phosphates, Na2Th(PO4)2, NaTh2(PO4)3 and Na5Th(PO4)3 was confirmed at 1223 K. XRD pattern of monoclinic Na5Th(PO4)3, synthesized for the first time and found iso structural with Na5Th(AsO4)3 and its lattice parameters were obtained by Le Bail method. Thermogravimetric studies of quaternary phosphates were carried out in air to investigate their thermal stability. All the three compounds decompose to ThO2 at 1673 K. Two step weight loss in TG curve of Na2Th(PO4)2 confirmed its decomposition to ThO2 via NaTh2(PO4)3 as an intermediate. To calculate thermal expansion coefficients, high temperature XRD (HT-XRD) data of Na2Th(PO4)2, NaTh2(PO4)3 and Na5Th(PO4)3 was collected in air between the temperature range of 298–1173 K. All these compounds exhibit positive thermal expansion with the average volume expansion coefficient values ranging between 30 and 60 × 10−6 K−1. Heat capacities of these compounds were measured in the temperature range of 308–873 K using Differential Scanning Calorimetry (DSC) technique.

Influence of the Homoatomic and Multicenter Bonding on the Formation of CsCl‐type RhCd

AbstractThe electronic structure and chemical bonding analysis of the recently uncovered CsCl‐type RhCd have been discussed thoroughly in this article. It is observed that a more complex combination of long‐range heteroatomic (Rh−Cd) and homoatomic (Rh−Rh and Cd−Cd) interactions as well as multicenter Rh−Cd−Rh interactions influence the formation of CsCl type‐RhCd. On the other hand, the other two structurally closely related phases (Rh2Cd5 and Rh3Cd5−δ) are mostly dominated by the partially covalent Rh−Cd heteroatomic interactions.