Apparent Position Research Articles

Ascending testis: A congenital predetermined condition

About 0.8% of boys have undescended testes at 1 year of age. However, the overall rate of orchidopexy is 2.5 times that expected. While studies have shown ascending testes accounting for a proportion of such discrepancy, the aetiology of this ascent remains controversial. In this study, intra-operative findings of patients underwent orchidopexy for ascending testes are evaluated to infer aetiology. Patients with confirmed ascending testes from a single paediatric surgery unit over a four-year period from June 2015 till June 2019 were included in this observational study. During orchidopexy procedure, intra-operative findings in terms of gubernacular attachment, and the degree of epididymal attachment to the upper pole of the testicle were primarily evaluated. Secondary findings including the presence and length of patent processus vaginalis (PPV), and the presence of any long looping vas or hydatid of morgangi were also noted. Eighty-three children (median age=79 months [range 38-149]) were included in this study. Two boys had bilateral ascending testes leading to a total of 85 orchidopexy cases performed. All patients were found to have a gubernacular attachment proximal to the junction between the upper lateral wall of scrotum and the medial part of the thigh. PPV was present in all cases, with its length measured from the deep inguinal ring after retracting the conjoint tendon ranging from 4 to 15mm 84 cases (98.8%) demonstrated complete or partial separation between the head of epididymis and the upper pole of the testicle. Hydatid of morgagni was present in 82 cases (96.4%), and none of the operated testicles demonstrated looping vas. The varying degrees of PPV length demonstrated during orchiodpexy for ascending testes in this study casts a doubt on the role of processus vaginalis in such ascent. Also, there is considerably a wide-range of reported incidence (13-78%) in literature for PPV in ascending testes. In this study, intra-operative findings demonstrated an abnormal gubernaculum attachment in all ascending testes in keeping with previous reports, and support the hypothesis that ascending testis has always been undescended, yet acquired more apparent undescended position with child age and growth. Patients with ascending testes seem to share similar intra-operative findings with patients who have true undescended testes. The universal abnormal attachment of the gubernaculum and the omnipresent testicular-epididymal fusion anomalies may indicate that ascending testis is a congenital predetermined condition, and that these testes have always been congenitally undescended, yet obtained a more noticeable position with the child growth.

Subsecond Time Evolution of Type III Solar Radio Burst Sources at Fundamental and Harmonic Frequencies

Abstract Recent developments in astronomical radio telescopes opened new opportunities in imaging and spectroscopy of solar radio bursts at subsecond timescales. Imaging in narrow frequency bands has revealed temporal variations in the positions and source sizes that do not fit into the standard picture of type III solar radio bursts, and require a better understanding of radio-wave transport. In this paper, we utilize 3D Monte Carlo ray-tracing simulations that account for the anisotropic density turbulence in the inhomogeneous solar corona to quantitatively explain the image dynamics at the fundamental (near plasma frequency) and harmonic (double) plasma emissions observed at ∼32 MHz. Comparing the simulations with observations, we find that anisotropic scattering from an instantaneous emission point source can account for the observed time profiles, centroid locations, and source sizes of the fundamental component of type III radio bursts (generated where f pe ≈ 32 MHz). The best agreement with observations is achieved when the ratio of the perpendicular to the parallel component of the wavevector of anisotropic density turbulence is around 0.25. Harmonic emission sources observed at the same frequency (∼32 MHz, but generated where f pe ≈ 16 MHz) have apparent sizes comparable to those produced by the fundamental emission, but demonstrate a much slower temporal evolution. The simulations of radio-wave propagation make it possible to quantitatively explain the variations of apparent source sizes and positions at subsecond timescales both for the fundamental and harmonic emissions, and can be used as a diagnostic tool for the plasma turbulence in the upper corona.

Dynamic Decoupling and Trajectory Tracking for Automated Vehicles Based on the Inverse System

A simultaneous trajectory tracking and stability control method is present for the four-wheel independent drive (4WID) automated vehicles to handle dynamic coupling maneuvers. To conquer the disadvantage that attendant disturbances caused by the dynamic coupling of traditional decentralized control methods degenerate the trajectory tracking accuracy, the proposed method takes advantage of the idea of decoupling to optimize the tracking performance. After establishing the dynamic model of the 4WID automated vehicles, the coupling mechanism of the vehicle dynamic control and its negative effect on trajectory tracking were studied at first. The inverse system model was then determined by machine learning and connected in series with the controlled object to form a pseudo linear system to realize dynamic decoupling. Finally, differing from previous tracking methods following the apparent lateral position and longitudinal velocity references, the pseudo linear system tracks the ideal intermediate targets transferred from the target trajectory, that is, the accelerations of vehicle in longitudinal, lateral and yaw directions, to indirectly achieve trajectory tracking and validly restrain the vehicle motion. The effectiveness of the proposed method, i.e., the high tracking accuracy and the stable driving performance, is verified through three coupling driving scenarios in the CarSim-Simulink co-simulations platform.

The KK principle and rotational symmetry

The KK principle and rotational symmetry

Holocene sea-level change on the central coast of Bohai Bay, China

Abstract. To constrain models on global sea-level change regional proxy data on coastal change are indispensable. Here, we reconstruct the Holocene sea-level history of the northernmost China Sea shelf. This region is of great interest owing to its apparent far-field position during the late Quaternary, its broad shelf and its enormous sediment load supplied by the Yellow River. This study generated 25 sea-level index points for the central Bohai coastal plain through the study of 15 sediment cores and their sedimentary facies, foraminiferal assemblages and radiocarbon dating the basal peat. The observational data were compared with sea-level predictions obtained from global glacio-isostatic adjustment (GIA) models and with published sea-level data from Sunda shelf, Tahiti and Barbados. Our observational data indicate a phase of rapid sea-level rise from c. −17 to −4 m between c. 10 and 5 ka with a peak rise of 6.4 mm a−1 during 8.7 to 7.5 ka and slower rise of 1.9 mm a−1 during 7.5 to 5.3 ka followed by a phase of slow rise from 5 to 2 ka (∼0.4 mm a−1 from −3.58 m at 5.3 ka cal BP to −2.15 m at 2.3 ka cal BP). The comparison with the sea-level predictions for the study area and the published sea-level data is insightful: in the early Holocene, Bohai Bay's sea-level rise is dominated by a combination of the eustatic and the water load components causing the levering of the broad shelf. In the mid to late Holocene the rise is dominated by a combination of tectonic subsidence and fluvial sediment load, which masks the mid-Holocene highstand recorded elsewhere in the region.

Frequency-adjustable magnetic field probes.

Nuclear Magnetic Resonance field probes provide exciting possibilities for enhancing MR image quality by allowing for calibration of k-space trajectories and/or dynamic measurement of local field changes. The purpose of this study is to design and build field probes, which are easier to manufacture and more flexible to use than existing probes. A new manufacturing method is presented based on light-activated resin to encase the coil assembly and the 1H sample. This method allows for realizing field probes with tightly integrated orthogonal coils, whereby the local resonance frequency of protons can be adjusted during the MR experiment, by applying a DC current to the integrated -field modification coil. The apparent field probe position in a gradient echo experiment was shifted within the field of view by changing its Larmor frequency using an integrated micro-coil with 5.5 windings. The measured frequency modulation induced by the -field modification coil was 113Hz/mA. The probe was tested with currents up to 100mA. The DC current in the local field modification coil did not introduce visible artifacts in the MR images. Furthermore selective off-resonant excitation of the new field probes at 2kHz above the main RF frequency was demonstrated. Gradient impulse response functions measured with a traditional and proposed probe show similar gradient imperfections. The presented approach opens up new possibilities for concurrent field monitoring during MR experiments using standard RF capabilities of clinical scanners.

Influence of the Galactic Gravitational Field on the Positional Accuracy of Extragalactic Sources. II. Observational Appearances and Detectability

Abstract We consider the possibility of detecting the jitter effect of apparent celestial positions of distant sources due to local fluctuations of the Galaxy gravitational field. The observation of two samples of extragalactic sources (target and control) in different sky directions using the high-precision radio interferometry is proposed. It is shown that on a scale of ∼2 yr, it is possible to detect a systematic increase in the standard deviation of measured arc lengths of pairs of target sources compared to the control ones at the 3σ level if the accuracy of differential astrometric observations is around 10 μas. For the current state-of-the-art accuracy of 30 μas achieved at the KVN or VERA interferometers, which have shorter baselines in comparison with very long baseline interferometry, the target and control samples will differ only at the 2σ level on the scale of 10 yr. To achieve the 3σ level on this time interval, it is necessary to improve the accuracy up to ∼20 μas. Other possible effects that can also affect the arc length measurements between two sources are discussed, and an observational strategy to minimize them is suggested.

Pelvic rotation after total hip arthroplasty is dynamic and variable.

The aims of this study were to determine the change in the sagittal alignment of the pelvis and the associated impact on acetabular component position at one-year follow-up after total hip arthroplasty (THA). This study represents the one-year follow-up of a previous short-term study at our institution. Using the patient population from our prior study, the radiological pelvic ratio was assessed in 91 patients undergoing THA, of whom 50 were available for follow-up of at least one year (median 1.5; interquartile range (IQR) 1.1 to 2.0). Anteroposterior radiographs of the pelvis were obtained in the standing position preoperatively and at one year postoperatively. Pelvic ratio was defined as the ratio between the vertical distance from the inferior sacroiliac (SI) joints to the superior pubic symphysis and the horizontal distance between the inferior SI joints. Apparent acetabular component position changes were determined from the change in pelvic ratio. A change of at least 5° was considered clinically meaningful. Pelvic ratio decreased (posterior tilt) in 54.0% (27) of cases, did not change significantly in 34.0% (17) of cases, and increased (anterior tilt) in 12.0% (6) of cases when comparing preoperative to one-year postoperative radiographs. This would correspond with 5° to 10° of abduction error in 22.0% of cases and > 10° of error in 6.0%. Likewise, this would correspond with 5° to 10° of version error in 22.0% of cases and > 10° of error in 44.0%. Pelvic sagittal alignment is dynamic and variable after THA, and these changes persist to the one-year postoperative period, altering the orientation of the acetabular component. Surgeons who individualize the acetabular component placement based on preoperative functional radiographs should consider that the rotation of the pelvis (and thus the component version and inclination) changes one year postoperatively. Cite this article: Bone Joint J 2020;102-B(7 Supple B):47-51.

A Cloud Top-Height Retrieval Algorithm Using Simultaneous Observations from the Himawari-8 and FY-2E Satellites

In this paper, we introduce a cloud top-height (CTH) retrieval algorithm using simultaneous observations from the Himawari-8 and FengYun (FY)-2E geostationary (GEO) satellites (hereafter, dual-GEO CTH algorithm). The dual-GEO CTH algorithm estimates CTH based on the parallax, which is the difference in the apparent position of clouds observed from two GEO satellites simultaneously. The dual-GEO CTH algorithm consists of four major procedures: (1) image remapping, (2) image matching, (3) CTH calculation, and (4) quality control. The retrieved CTHs were compared with other satellite CTHs from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and the Cloud-Profiling Radar (CPR), on three occasions. Considering the geometric configuration and footprint sizes of the two GEO satellites, the theoretical accuracy of the dual-GEO CTH algorithm is estimated as ±0.93 km. The comparisons show that the retrieval accuracy generally tends to fall within the theoretical accuracy range. As the dual-GEO CTH algorithm is based on parallax, it could be easily applied for the estimation of the height of any elevated feature in various fields.

Virtual image of a hand displaced in space influences action performance of the real hand

The rubber hand illusion (RHI) demonstrates that under some circumstances a fake hand can be regarded as part of one’s body; the RHI and related phenomena have been used to explore the flexibility of the body schema. Recent work has shown that a sense of embodiment may be generated by virtual reality (VR). In a series of experiments, we used VR to assess the effects of the displacement of the virtual image of subjects’ hands on action. Specifically, we tested whether spatial and temporal parameters of action change when participants perform a reaching movement towards the location of their virtual hand, the position of which was distorted on some trials. In different experiments, participants were sometimes provided with incorrect visual feedback regarding the position of the to-be-touched hand (Experiment 1), were deprived of visual feedback regarding the position of the reaching hand when acting (Experiment 2) or reached with the hand, the apparent position of which had been manipulated (Experiment 3). The effect was greatest when participants reached towards (Experiment 1) or with (Experiment 3) the displaced hand when the hand was visible during the reaching, but not when the vision of the hand was removed during the action (Experiment 2). Taken together, these data suggest that visual images of one’s hand presented in VR influence the body schema and action performance.

Gamow’s cyclist: a new look at relativistic measurements for a binocular observer

The visualization of objects moving at relativistic speeds has been a popular topic of study since Special Relativity's inception. While the standard exposition of the theory describes certain shape-changing effects, such as the Lorentz-contraction, it makes no mention of how an extended object would appear in a snapshot or how apparent distortions could be used for measurement. Previous work on the subject has derived the apparent form of an object, often making mention of George Gamow's relativistic cyclist thought experiment. Here, a rigorous re-analysis of the cyclist, this time in three dimensions, is undertaken for a binocular observer, accounting for both the distortion in apparent position and the relativistic colour and intensity shifts undergone by a fast-moving object. A methodology for analysing binocular relativistic data is then introduced, allowing the fitting of experimental readings of an object's apparent position to determine the distance to the object and its velocity. This method is then applied to the simulation of Gamow's cyclist, producing self-consistent results.

Universal algorithm for water depth refraction correction in through-water stereo remote sensing

In through-water stereo remote sensing, the correction of the effect of light refraction on water depth determination is an unsolved problem. The challenge is that no solution exists for apparent positions when the conjugate image rays are non-intersecting. This paper proposes a new water depth refraction correction algorithm for through-water stereo remote sensing. The midpoint of the shortest line segment between two non-intersecting conjugate image rays is used as the apparent position, so that the mathematical relationship between the apparent and actual depths is established under the “no solution condition”. The new algorithm is reasonable and applicable whether or not conjugate image rays are intersecting. Compared with the existing algorithms, the new algorithm can improve bathymetric accuracy in different degrees. The improvement becomes more significant as the off-nadir view angle difference and the depth increase. Results for Area 1 showed that, compared with the three existing algorithms, the new algorithm improved RMSE accuracy by about 22%, 29% and 24% respectively. The new algorithm enables reasonable water depth refraction correction to be implemented in any case (whether conjugate image rays are intersecting or not).

Eclipses of continuous gravitational waves as a probe of stellar structure

Although gravitational waves only interact weakly with matter, their propagation is affected by a gravitational potential. If a gravitational wave source is eclipsed by a star, measuring these perturbations provides a way to directly measure the distribution of mass throughout the stellar interior. We compute the expected Shapiro time delay, amplification and deflection during an eclipse, and show how this can be used to infer the mass distribution of the eclipsing body. We identify continuous gravitational waves from neutron stars as the best candidates to detect this effect. When the Sun eclipses a far-away source, depending on the depth of the eclipse the time-delay can change by up to $\sim 0.034$ ms, the gravitational-wave strain amplitude can increase by $\sim 4$%, and the apparent position of the source in the sky can vary by $4''$. Accreting neutron stars with Roche-lobe filling companion stars have a high probability of exhibiting eclipses, producing similar time delays but undetectable changes in amplitude and sky location. Even for the most rapidly rotating neutron stars, this time delay only corresponds to a few percent of the phase of the gravitational wave, making it an extremely challenging measurement. However, if sources of continuous gravitational waves exist just below the limit of detection of current observatories, next-generation instruments will be able to observe them with enough precision to measure the signal of an eclipsing star. Detecting this effect would provide a new direct probe to the interior of stars, complementing asteroseismology and the detection of solar neutrinos.

Astrometric effects of gravitational wave backgrounds with nonluminal propagation speeds

A passing gravitational wave causes a deflection in the apparent astrometric positions of distant stars. The effect of the speed of the gravitational wave on this astrometric shift is discussed. A stochastic background of gravitational waves would result in a pattern of astrometric deflections which are correlated on large angular scales. These correlations are quantified and investigated for backgrounds of gravitational waves with sub- and super-luminal group velocities. The statistical properties of the correlations are depicted in two equivalent and related ways: as correlation curves and as angular power spectra. Sub-(super-)luminal gravitational wave backgrounds have the effect of enhancing (suppressing) the power in low-order angular modes. Analytical representations of the redshift-redshift and redshift-astrometry correlations are also derived. The potential for using this effect for constraining the speed of gravity is discussed.

A Simple and Efficient Image Stabilization Method for Coastal Monitoring Video Systems

Fixed video camera systems are consistently prone to importune motions over time due to either thermal effects or mechanical factors. Even subtle displacements are mostly overlooked or ignored, although they can lead to large geo-rectification errors. This paper describes a simple and efficient method to stabilize an either continuous or sub-sampled image sequence based on feature matching and sub-pixel cross-correlation techniques. The method requires the presence and identification of different land-sub-image regions containing static recognizable features, such as corners or salient points, referred to as keypoints. A Canny edge detector ( C E D ) is used to locate and extract the boundaries of the features. Keypoints are matched against themselves after computing their two-dimensional displacement with respect to a reference frame. Pairs of keypoints are subsequently used as control points to fit a geometric transformation in order to align the whole frame with the reference image. The stabilization method is applied to five years of daily images collected from a three-camera permanent video system located at Anglet Beach in southwestern France. Azimuth, tilt, and roll deviations are computed for each camera. The three cameras showed motions on a wide range of time scales, with a prominent annual signal in azimuth and tilt deviation. Camera movement amplitude reached up to 10 pixels in azimuth, 30 pixels in tilt, and 0.4° in roll, together with a quasi-steady counter-clockwise trend over the five-year time series. Moreover, camera viewing angle deviations were found to induce large rectification errors of up to 400 m at a distance of 2.5 km from the camera. The mean shoreline apparent position was also affected by an approximately 10–20 m bias during the 2013/2014 outstanding winter period. The stabilization semi-automatic method successfully corrects camera geometry for fixed video monitoring systems and is able to process at least 90% of the frames without user assistance. The use of the C E D greatly improves the performance of the cross-correlation algorithm by making it more robust against contrast and brightness variations between frames. The method appears as a promising tool for other coastal imaging applications such as removal of undesired high-frequency movements of cameras equipped in unmanned aerial vehicles (UAVs).

Apparent beacon position estimation for accuracy improvement in lateration positioning system

Lateration based systems with stationary beacons are commonly used in position estimation. Although the idea of lateration is simple in principle, in practice it is influenced by multiple sources of errors, such as: imprecise beacon position calibration, obstacles, reflections, variable effective signal propagation speed, and other environmental disturbances. These errors can be attenuated by employment of a correction method. In the following paper we present the application of the Apparent Beacon Position Estimation (ABPE) method to improve the accuracy of an indoor lateration based positioning system. The idea of the method is to estimate the beacons’ positions as perceived by the receiver, and then to apply these apparent beacons’ positions in the localization algorithm. The proposed method was verified in an experimental setup. We show that ABPE offers a better accuracy improvement and requires fewer calibration reference points than other commonly utilized methods based on the bias and scale factor, and second-order polynomial transformation.

MANAGERIAL CAPITAL AS A SPECIAL FACTOR OF THE MODERN ORGANIZATION'S COMPETITIVENESS

In the modern economic state and capitalistic society, a certain tendency can be seen due to expanding markets, stip rise of IT-technologies and innovations. In order to thrive, companies shall obtain a specific kit of tools in order to reach a desirable level of their competitive advantage. This is the crucial success factor one should always pay attention to. However, it should be noted that gaining and acquiring, evolving, and sustaining the raw material base is a smooth process while mastering knowledge, skills, ideas – here is a shaky ground to walk on. That is the moment when we refer to the term 'managerial capital' which, unfortunately, does not get fully recognized among scientists due to its newness, leading to the fact of falsely compared and included into intellectual capital. The goal, therefore, is to show the independence and sufficiency of the 'managerial capital'. Give the modern explanation of it how we understand it. Compare it to other forms of capital, such as intellectual capital and physical capital. Build connections and stress the uniqueness of managerial capital through other capital's functions. To follow our goal, we have decided to analyze the existing base of knowledge regarding this topic. In this analysis complex of the general scientific and specific research methods were used to achieve the goal of the study. The method of historical and logical analysis of the literature was used. Method of comparative analysis was used to study the common and different between managerial, intellectual and physical capitals. Method of summarization was used to conclude. Scientific works of national scientists and international legal documents were used as the informational basis for the conducted research. According to the research made, we may conclude to the eligibility of equaling managerial capital to so-called 'meta-form' that stands above other capitals and possesses such feature as a “gluing effect” becoming a significant factor in forming competitive advantage. Conduction of justified measures of development is an essential step to becoming a company with an apparent position on the market.

Effects of disturbance of seawater excited by internal wave on GNSS-acoustic positioning

Traditional Global Navigation Satellite System-Acoustic (GNSS-A) positioning assumes the Layered Model in the sound speed structure, and any of horizontal perturbation of seawater degrades its accuracy. However, the use of the Gradient Model analytically demonstrated that the horizontal gradient of the sound speed structure and displacement can simultaneously be solved using multiple transponders for each of ping. We applied this technique to our observed data and found it unsuitable for real data. We confirmed that a horizontal perturbation with wavelength shorter than the horizontal extent of the transponder array significantly violates the linear approximation in the Gradient Model. Our vertical 2D numerical simulation of internal waves (IWs) forced by tidal oscillation showed that such small-scale IWs could effectively be generated by nonlinear cascade from large-scale IWs of the major tidal constituents. In addition, a small-scale IW in deep water typically has a period of 3–4 h, which degrades positioning accuracy significantly, whereas an IW of much shorter period in shallow water has less effect after removal of the fluctuation by time averaging within a typical observation period. Apparent array position obtained in the synthetic test based on the simulated IW-derived sound speed structure showed features quite similar to that observed in real surveys. To incorporate such deeper perturbation, we proposed a Disturbance Model using dual sea surface platforms, that can solve time-varying perturbation in the vicinity of each transponder.

A Nomenclature for Critical Autoethnography in the Arena of Disciplinary Atomization

This article proposes the nomenclatural shifting of “evocative” autoethnography (EVAT) from its apparent current position as a co-type of autoethnography to a lead or superordinate type of evocative-like autoethnography, with the suggested name of “critically-oriented evocative autoethnography as a methodology without methods and situated within critical qualitative inquiry” (CEAM-CQI). In this lead position, EVAT as CEAM-CQI could maintain a unified and mediated stance alongside its apparent nemesis, “analytical autoethnography” (ANAT), by way of “disciplinary atomization,” which at first seems undesirable but then proves beneficial if mediated by ego-less critique and polyvocality (Gergen), and as a result, EVAT, now CEAM-CQI, perhaps could more fully achieve its social justice agenda.

SIMS of organic layers with unknown matrix parameters: Locating the interface in dual beam argon gas cluster depth profiles

Four simple methods are evaluated to determine their accuracies for establishing the interface location in secondary ion mass spectrometry intensity depth profiles of organic layers where matrix effects have not been measured. Accurate location requires the separate measurement of each ion's matrix factor. This is often not possible, and so estimates using matrix‐less methods are required. Six pure organic material interfaces are measured using many secondary ions to compare their locations from the four methods with those from full evaluation with matrix terms. For different secondary ions, matrix effects cause the apparent interface positions to vary over 20 nm. The shifts in the intensity profiles on going from a layer of P into a layer of Q are in the opposite direction to that for going from Q into P, so doubling layer thickness errors. The four methods are as follows: M1, use of the median interface position in the intensity profiles for the five lightest ions for 15 ≤ m/z ≤ 150; M2, extrapolation of the position for each ion to m/z = 0 for ions with m/z ≤ 150; M3, as M2 but for m/z ≤ 300; and M4, the extreme positions for all m/z ≤ 100. Comparison with the location using matrix terms shows their ranking, from best to worst, to be M4, M3, M1, and M2 with average errors of 10%, 12%, 14%, and 17%, respectively, of the profile interface full widths at half maximum. Use of pseudo‐molecular ions is very much poorer, exceeding 50%, and should be avoided.