Sensitivity Of Rotation Research Articles

Sensitivity of a Point-Source-Interferometry-Based Inertial Measurement Unit Employing Large Momentum Transfer and Launched Atoms

We analyze theoretically the sensitivity of accelerometry and rotation sensing with a point source interferometer employing large momentum transfer (LMT) and present a design of an inertial measurement unit (IMU) that can measure rotation around and acceleration along each of the three axes. In this design, the launching technique is used to realize the LMT process without the need to physically change directions of the Raman pulses, thus significantly simplifying the apparatus. We also describe an explicit scheme for such an IMU.

Spin and valley-polarized Faraday rotation in irradiated buckled Xene materials

This study delves into the theoretical exploration of Faraday rotation and ellipticity in light beams transmitted through buckled Xene materials. These materials undergo topological phase transitions (TPTs), shifting from topologically non-trivial to trivial systems under the influence of an off-resonance irradiated laser field or a staggered electric potential. Specifically, we investigate the manifestation of these phenomena when the buckled Xene material is exposed to an off-resonant laser and staggered sublattice potential. Using the Kubo formula, we derive the optical conductivities of the buckled Xene material to analyze transmission spectra through Fresnel’s transmission coefficients. Additionally, we calculate the spin and valley-dependent Faraday rotation angles and ellipticities of the buckled Xene by selecting suitable parameters for the circularly polarized off-resonant laser field and staggered electric potential across distinct topological quantum phases. Our findings reveal a high sensitivity of Faraday rotation and ellipticity to the topological invariants. In particular, we find that due to the broken time-reversal symmetry (TRS), the amount of the maximum spin and valley polarized Faraday rotation angle and ellipticity in irradiated buckled Xene material without magnetic field are ≊±0.53∘ and ≊±0.2∘, respectively. Our results suggest possible techniques for probing topological numbers and topological phase transitions in buckled Xene materials by Faraday rotation.

Effects of postural threat on perceptions of lower leg somatosensory stimuli during standing.

Height-induced postural threat affects emotional state and standing balance behaviour during static, voluntary, and dynamic tasks. Facing a threat to balance also affects sensory and cortical processes during balance tasks. As sensory and cognitive functions are crucial in forming perceptions of movement, balance-related changes during threatening conditions might be associated with changes in conscious perceptions. Therefore, the purpose of this study was to examine the changes and potential mechanisms underlying conscious perceptions of balance-relevant information during height-induced postural threat. A combination of three experimental procedures utilized height-induced postural threat to manipulate emotional state, balance behavior, and/or conscious perceptions of balance-related stimuli. Experiment 1 assessed conscious perception of foot position during stance. During continuous antero-posterior pseudorandom support surface rotations, perceived foot movement was larger while actual foot movement did not change in the High (3.2 m, at the edge) compared to Low (1.1 m, away from edge) height conditions. Experiment 2 and 3 assessed somatosensory perceptual thresholds during upright stance. Perceptual thresholds for ankle rotations were elevated while foot sole vibrations thresholds remained unchanged in the High compared to Low condition. This study furthers our understanding of the relationship between emotional state, sensory perception, and balance performance. While threat can influence the perceived amplitude of above threshold ankle rotations, there is a reduction in the sensitivity of an ankle rotation without any change to foot sole sensitivity. These results highlight the effect of postural threat on neurophysiological and cognitive components of balance control and provide insight into balance assessment and intervention.

Sensitivity and Specificity Predictive Value of The Hip Internal Rotation with Distraction (THIRD) Test for Hip Labral Tears

This study evaluated the diagnostic test characteristics of Myrick The Hip Internal Rotation with Distraction (THIRD) vs magnetic resonance imaging (MRI) or magnetic resonance arthrogram (MRA) for diagnosing hip labral pathology. A 7-year retrospective medical record review was performed. All medical records that had the chief complaint of hip pain with documentation of THIRD, MRI or MRA, and arthroscopic findings (ie, gold standard) were pulled, and data were extracted for findings of each of the tests. There were 81 records. Compared with MRI/MRA, THIRD had significantly better sensitivity (91% vs 65%, <i>P</i> <.001) and accuracy (89% vs 64%, <i>P</i> < .001). THIRD outperformed MRI/MRA and is a noninvasive, low-cost procedure to diagnosis hip labral pathology.

Sensitivity enhancement of micro-optical gyro with photonic crystal* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11804066 and 61773133), Heilongjiang Provincial Natural Science Foundation of China (Grant No. LH2019A005), China Postdoctoral Science Foundation (Grant No. 2018M630337), and Heilongjiang Provincial Postdoctoral Science Foundation (Grant No. LBHZ18062).

We propose a core rotation-sensing element for improving the sensitivity of the micro-optical gyroscope using the large nonreciprocal effect with a photonic crystal. The sharp transmission peak of electromagnetically induced transparency in photonic crystal generated from a periodic distribution of cold atoms is sensitive to the rotation. Our numerical results show that the sensitivity of relative rotation is about 50 times higher and the sensitivity of absolute rotation is more than two orders higher than that of the traditional resonant optical gyroscope. Also, the sensitivity of the gyroscope can be manipulated by varying the atomic density, modulation frequency, probe pulse width, and photonic crystal length, etc.

Design of a calorimeter for near-field heat transfer measurements and thermal scanning probe microscopy.

Multilayer cantilever beams are used in the measurement of near-field radiative heat transfer. The materials and dimensions of the cantilever probe are chosen in order to improve system performance in terms of sensitivity and noise. This is done using an analytical model that describes the thermo-mechanical and mechanical behavior of the cantilever and its influences at the system level. In the design, the optical reflectance and the sensitivity of cantilever rotation to the heat input are maximized under constraints for thermal noise, temperature drift, and a lower bound for the spring constant. The analytical model is verified using finite element analysis, which shows that the effects of radiative losses to the environment are insignificant for design purposes, while the effects of ignoring three-dimensional heat flow introduces larger errors. Moreover, the finite element analysis shows that the designed probes are up to 41 times more sensitive than the often used commercial-of-the-shelf benchmark and have a four times lower thermal noise. Experimental validation of the designed probes shows good agreement with the theoretical values for sensitivity. However, the most sensitive designs were found to be susceptible to damage due to overheating and carbon contamination.

AGE–GENDER DIFFERENCE IN THE PERCEPTION AND MUSCLE RESPONSE THRESHOLDS OF SUPPORT SURFACE ROTATION

Proprioception while standing is important for the balance control, but the proprioception has not been investigated in the unconstrained standing conditions. The purpose of this study was to investigate the effects of age and gender on the thresholds of perception and muscle response in response to the support surface rotation. The experiment was designed so that the thresholds depend mainly on the proprioception, i.e., quasistatic condition (0.2∘/s rotation of the platform) with eyes closed. Fifty-two healthy subjects (half young and half elderly) participated in this study. A platform was developed which can be rotated in four directions. Perception threshold angle was registered from subjects’ pressing a button. Muscle response threshold angle was determined as the earlier onset of EMG in lower limb muscles. Two standing conditions (feet together and natural stance) were tested. Repeated-measures ANOVA showed that both thresholds increased with age. Post hoc tests revealed (1) that the perception threshold was greater for women than men in the elderly and (2) both thresholds of the elderly were greater for the feet-together stance than natural stance. Inferior perception sensitivity of platform rotation in elderly women may be associated with inferior performance in cortical postural control and greater fall ratio compared to elderly men, which suggests the need of proprioception trainings.

Identifying damage on a bridge using rotation-based Bridge Weigh-In-Motion

Bridge Weigh-in-Motion (B-WIM) systems use the bridge response under a traversing vehicle to estimate its axle weights. The information obtained from B-WIM systems has been used for a wide range of applications such as pre-selection for weight enforcement, traffic management/planning and for bridge and pavement design. However, it is less often used for bridge condition assessment purposes which is the main focus of this study. This paper presents a bridge damage detection concept using information provided by B-WIM systems. However, conventional B-WIM systems use strain measurements which are not sensitive to local damage. In this paper the authors present a B-WIM formulation that uses rotation measurements obtained at the bridge supports. There is a linear relationship between support rotation and axle weight and, unlike strain, rotation is sensitive to damage anywhere in the bridge. Initially, the sensitivity of rotation to damage is investigated using a hypothetical simply supported bridge model. Having seen that rotation is damage-sensitive, the influence of bridge damage on weight predictions is analysed. It is shown that if damage occurs, a rotation-based B-WIM system will continuously overestimate the weight of traversing vehicles. Finally, the statistical repeatability of ambient traffic is studied using real traffic data obtained from a Weigh-in-Motion site in the U.S. under the Federal Highway Administration’s Long-Term Pavement Performance programme and a damage indicator is proposed as the change in the mean weights of ambient traffic data. To test the robustness of the proposed damage detection methodology numerical analysis are carried out on a simply supported bridge model and results are presented within the scope of this study.

Identifying damage in a bridge by analysing rotation response to a moving load

This article proposes a bridge damage detection method using direct rotation measurements. Initially, numerical analyses are carried out on a one-dimensional (1D) simply supported beam model loaded with a single moving point load to investigate the sensitivity of rotation as a main parameter for damage identification. As a result of this study, the difference in rotation measurements due to a single moving point load obtained for healthy and damaged states is proposed as a damage indicator. A relatively simple laboratory experiment is conducted on a 3-m long simply supported beam structure to validate the results obtained from the numerical analysis. The case of multi-axle vehicles is investigated through numerical analyses of a 1D bridge model and a theoretical basis for damage detection is presented. Finally, a sophisticated 3D dynamic finite element model of a 20-m long simply supported bridge structure is developed by an independent team of researchers and used to test the robustness of the proposed damage detection methodology in a series of blind tests. Rotations from an extensive range of damage scenarios were provided to the main team who applied their methods without prior knowledge of the extent or location of the damage. Results from the blind test simulations demonstrate that the proposed methodology provides a reasonable indication of the bridge condition for all test scenarios.

Bridge damage detection using rotation measurements – Experimental validation

• Rotation is a sensitive parameter for identifying damage in a bridge. • Rotation can be accurately measured using a high-grade DC accelerometer. • Difference in rotation influence lines for healthy and damaged states successfully identifies damage in a model bridge. • For simply supported bridges, supports are optimum sensor locations for damage identification. This paper presents a novel bridge condition assessment methodology using direct rotation measurements. Initially, numerical analyses are carried out to develop the theoretical basis of the proposed bridge damage detection methodology. As a result of this study the difference in rotation influence lines obtained for healthy and damaged bridge states is proposed as a damage indicator. The sensitivity of rotation to damage and the effect of sensor locations on sensor sensitivities are investigated. Subsequently, extensive laboratory experiments are conducted on a 5.4 m long simply supported bridge structure in an effort to validate the results from the numerical analyses. The test structure is instrumented with rotation sensors and axle detectors and loaded with a four-axle moving vehicle. In this study, rotations are measured using high grade uniaxial accelerometers. The procedure of measuring rotations using accelerometers is explained within the scope of this study. To test the robustness of the proposed bridge condition assessment methodology, a wide range of single and multiple damage scenarios is investigated and the results from this study show that the proposed methodology can successfully identify damage on a bridge. For the model considered, damage as low as 7% change in stiffness over an extent of 2.5% bridge span is shown to be detectable.

Enhancing the sensitivity of rotation in a multiatom Sagnac interferometer

We investigate quantum sensing of rotation with a multi-atom Sagnac interferometer and present multi-partite entangled states to enhance the sensitivity of rotation frequency. For studying the sensitivity, we first present a Hermitian generator with respect to the rotation frequency. The generator, which contains the Sagnac phase, is a linear superposition of a z component of the collective spin and a quadrature operator of collective bosons depicting the trapping modes, which enables us to conveniently study the quantum Fisher information (QFI) for any initial states. With the generator, we derive the general QFI which can be of square dependence on the particle number, leading to Heisenberg limit. And we further find that the QFI may be of biquadratic dependence on the radius of the ring which confines atoms, indicating that larger QFI is achieved by enlarging the radius. In order to obtain the square and biquadratic dependence, we propose to use partially and globally entangled states as inputs to enhance the sensitivity of rotation.

Response Sensitivity to Design Parameters of RV Reducer

Dynamic characteristic significantly affects performance of RV reducer. The current researches mainly pay attention to free vibration properties of RV reducer. In order to satisfy the increasing demand on high performance, response sensitivity is analytically studied on the basis of cyclic symmetry structure. Based on the structure characteristics, a dynamic model is developed by taking into account the influence of bearing stiffness, crankshaft bending stiffness and mesh stiffness within planetary and cycloidal stages. For the model, governing equation of motion is derived and solved by Fourier series method. The solution revealed that forced vibrations at primary frequency are well defined structural. There exist three typical forced vibration modes: rotational, translational and planetary component modes. Response sensitivity to basic design parameters is obtained as closed-form expressions by differential method. With the typical vibration modes, response sensitivity is simplified and classified into three types. Calculation of sensitivity implies that vibrations of the output wheel are sensitive to eccentricity. As eccentricity increases, sensitivity of translation decreases first and then increases, but sensitivity of rotation always increases. The proposed method for analyzing response sensitivity provides some principles for selecting parameters for RV reducer from the point of view of forced vibration.

Dynamical heterogeneities of rotational motion in room temperature ionic liquids evidenced by molecular dynamics simulations.

Room temperature ionic liquids (RTILs) have been shown to exhibit spatial heterogeneity or structural heterogeneity in the sense that they form hydrophobic and ionic domains. Yet studies of the relationship between this structural heterogeneity and the ∼picosecond motion of the molecular constituents remain limited. In order to obtain insight into the time scales relevant to this structural heterogeneity, we perform molecular dynamics simulations of a series of RTILs. To investigate the relationship between the structures, i.e., the presence of hydrophobic and ionic domains, and the dynamics, we gradually increase the size of the hydrophobic part of the cation from ethylammonium nitrate (EAN), via propylammonium nitrate (PAN), to butylammonium nitrate (BAN). The two ends of the organic cation, namely, the charged Nhead-H group and the hydrophobic Ctail-H group, exhibit rotational dynamics on different time scales, evidencing dynamical heterogeneity. The dynamics of the Nhead-H group is slower because of the strong coulombic interaction with the nitrate counter-ionic anions, while the dynamics of the Ctail-H group is faster because of the weaker van der Waals interaction with the surrounding atoms. In particular, the rotation of the Nhead-H group slows down with increasing cationic chain length, while the rotation of the Ctail-H group shows little dependence on the cationic chain length, manifesting that the dynamical heterogeneity is enhanced with a longer cationic chain. The slowdown of the Nhead-H group with increasing cationic chain length is associated with a lower number of nitrate anions near the Nhead-H group, which presumably results in the increase of the energy barrier for the rotation. The sensitivity of the Nhead-H rotation to the number of surrounding nitrate anions, in conjunction with the varying number of nitrate anions, gives rise to a broad distribution of Nhead-H reorientation times. Our results suggest that the asymmetry of the cations and the larger excluded volume for longer cationic chain are important for both the structural heterogeneity and the dynamical heterogeneities. The observed dynamical heterogeneities may affect the rates of chemical reactions depending on where the reactants are solvated in ionic liquids and provide an additional guideline for the design of RTILs as solvents.

Solvent, temperature and concentration effects on the optical rotatory dispersion of (R)-3-methylcyclohexanone

Optical rotatory dispersion (ORD) spectra are reported for isolated and solvated (R)-3-methylcyclohexanone (R-3MCH) in 10 solvents, of wide polarity range, and over the spectral range 350–650 nm. Sample concentration effects on ORD spectra of R-3MCH were also recorded and investigated over widely varying concentrations from 2.5 × 10−3 to 2.5 × 10−1 g/mL where an observed sensitivity of optical rotation (OR) to incident light wavelength at low concentrations is correlated to solvent effects. Temperature effects were also studied by recording ORD spectra over the temperature range 0–65 °C in toluene. Recorded specific OR was plotted against various solvent parameters, namely, dipole moment, polarity, refractive index and polarizability to probe solvent effects. Furthermore, solvent effects were studied by incorporating Kamlet's and Taft's solvent parameters in the multi-parametric linear fitting. Theoretically, ORD spectra and populations of optimized geometries of equatorial and axial conformers of R-3MCH were calculated in the gas and solvated phases. All theoretical calculations were performed employing the polarizable continuum model using density functional theoretical and composite scheme (G4) methods with aug-cc-pVTZ and aug-cc-pVDZ basis sets. Net ORD spectra of R-3MCH were generated by the Boltzmann-weighted sum of the contributions of the dominant conformers. Upon comparing theoretical and experimental ORD spectra, a very good agreement is observed for the ORD spectra in the gas phase and high polarity solvents compared to relatively lesser agreement in low polarity solvents.

Multi-channel transport experiments at Alcator C-Mod and comparison with gyrokinetic simulations

Multi-channel transport experiments have been conducted in auxiliary heated (Ion Cyclotron Range of Frequencies) L-mode plasmas at Alcator C-Mod [Marmar and Alcator C-Mod Group, Fusion Sci. Technol. 51(3), 3261 (2007)]. These plasmas provide good diagnostic coverage for measurements of kinetic profiles, impurity transport, and turbulence (electron temperature and density fluctuations). In the experiments, a steady sawtoothing L-mode plasma with 1.2 MW of on-axis RF heating is established and density is scanned by 20%. Measured rotation profiles change from peaked to hollow in shape as density is increased, but electron density and impurity profiles remain peaked. Ion or electron heat fluxes from the two plasmas are the same. The experimental results are compared directly to nonlinear gyrokinetic theory using synthetic diagnostics and the code GYRO [Candy and Waltz, J. Comput. Phys. 186, 545 (2003)]. We find good agreement with experimental ion heat flux, impurity particle transport, and trends in the fluctuation level ratio (T̃e/Te)/(ñe/ne), but underprediction of electron heat flux. We find that changes in momentum transport (rotation profiles changing from peaked to hollow) do not correlate with changes in particle transport, and also do not correlate with changes in linear mode dominance, e.g., Ion Temperature Gradient versus Trapped Electron Mode. The new C-Mod results suggest that the drives for momentum transport differ from drives for heat and particle transport. The experimental results are inconsistent with present quasilinear models, and the strong sensitivity of core rotation to density remains unexplained.

Phase sensitivity of rotation sensing in coupled resonator waveguides

The dispersion of optical resonator structures can be used to increase the sensitivity of rotation sensing. Using coupled resonator waveguides can realize strong dispersion. In this paper, the transfer matrix method is used to analyze the phase sensitivity of rotation sensing in coupled resonator waveguides, and investigate the influences of resonator arrangement and waveguide parameters on the phase sensitivity. Results show that phase curves and phase sensitivity are dependent on resonator arrangement. The number of resonator and coupling coefficients can influence not only the number and bandwidths of peaks for phase sensitivity of rotation sensing but also the variation of phase sensitivity. However, loss can reduce the phase sensitivity. The results can be used to design the phase sensitivity of coupled resonator waveguides using the resonator arrangement and waveguide parameters, and are beneficial for applications of coupled resonator waveguides in rotation sensing.

Noncompaction cardiomyopathy, a frequently overlooked entity (…but beware of over diagnosis!)

Noncompaction cardiomyopathy, a frequently overlooked entity (…but beware of over diagnosis!)

Influence of the measurement method of features in ultrasound images of the thyroid in the diagnosis of Hashimoto’s disease

IntroductionThis paper shows the influence of a measurement method of features in the diagnosis of Hashimoto’s disease. Sensitivity of the algorithm to changes in the parameters of the ROI, namely shift, resizing and rotation, has been presented. The obtained results were also compared to the methods known from the literature in which decision trees or average gray level thresholding are used.MaterialIn the study, 288 images obtained from patients with Hashimoto’s disease and 236 images from healthy subjects have been analyzed. For each person, an ultrasound examination of the left and right thyroid lobe in transverse and longitudinal sections has been performed.MethodWith the use of the developed algorithm, a discriminant analysis has been conducted for the following five options: linear, diaglinear, quadratic, diagquadratic and mahalanobis. The left and right thyroid lobes have been analyzed both together and separately in transverse and longitudinal sections. In addition, the algorithm enabled to analyze specificity and sensitivity as well as the impact of sensitivity of ROI shift, repositioning and rotation on the measured features.Results and summaryThe analysis has shown that the highest accuracy was obtained for the longitudinal section (LD) with the method of linear, yielding sensitivity = 76%, specificity = 95% and accuracy ACC = 84%. The conducted sensitivity assessment confirms that changes in the position and size of the ROI have little effect on sensitivity and specificity. The analysis of all cases, that is, images of the left and right thyroid lobes in transverse and longitudinal sections, has shown specificity ranging from 60% to 95% and sensitivity from 62% to 89%. Additionally, it was shown that the value of ACC for the method using decision trees as a classifier is equal to 84% for the analyzed data. Thresholding of average brightness of the ROI gave ACC equal to 76%.

Ultrahigh sensitivity of rotation sensing beyond the trade-off between sensitivity and linewidth by the storage of light in a dynamic slow-light resonator

We propose to employ the storage of light in a dynamically tuned add-drop resonator to realize an optical gyroscope of ultrahigh sensitivity and compact size. Taking the impact of the linewidth of incident light on the sensitivity into account, we investigate the effect of rotation on the propagation of a partially coherent light field in this dynamically tuned slow-light structure. It is demonstrated that the fundamental trade-off between the rotation-detection sensitivity and the linewidth will be overcome and the sensitivity-linewidth product will be enhanced by two orders of magnitude in comparison to that of the corresponding static slow-light structure. Furthermore, the optical gyroscope employing the storage of light in the dynamically tuned add-drop resonator can acquire ultrahigh sensitivity by extremely short fiber length without a high-performance laser source of narrow linewidth and a complex laser frequency stabilization system. Thus the proposal in this paper provides a promising and feasible scheme to realize highly sensitive and compact integrated optical gyroscopes by slow-light structures.

A gigahertz-bandwidth atomic probe based on the slow-light Faraday effect

The ability to probe quantum systems on short timescales is central to the advancement of quantum technology. Here we show that this is possible using an off-resonant dispersive probe. By applying a magnetic field to an atomic vapour the spectra of the group index for left and right circularly polarized light become displaced, leading to a slow-light Faraday effect that results in large dispersion and high transmission over tens of gigahertz. This large frequency range opens up the possibility of probing dynamics on a nanosecond timescale. In addition, we show that the group index enhances the spectral sensitivity of the polarization rotation, giving large rotations of up to 15π rad for continuous-wave light. Finally, we demonstrate dynamic broadband pulse switching by rotating a linearly polarized nanosecond pulse by π/2 rad with negligible distortion and transmission close to unity. By applying a magnetic field to an atomic vapour, it is shown that the large bandwidth of off-resonance slow-light media can be combined with the Faraday effect to realize a high-bandwidth dispersive probe for atomic systems. This will open up the possibility of probing atomic dynamics on a nanosecond timescale.