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In the past, a variety of methods have been explored to determine the center of gravity or gravity line, such as the hanging method or force plate analysis. However, these methods possess limitations related to precise location of center of gravity. The aim of this study was to describe a tissue separation method to precisely calculate the center of gravity in upper trunk. Twenty post-operative patients with thoracolumbar kyphosis were retrospectively studied. Center of gravity models were computed: T1–T5 segment, T6–T10 segment and T1–T10 segment. The tissue separation method was used to calculate the center of gravity in each segment. A new center of gravity was composited from T1–T5 segment and T6–T10 segment by composition formula. Similarity and collinearity between center of gravity models was analyzed to verify the reliability of tissue separation method. Correlation between gravity line and theoretic hip axis was compared on pre- and post-operative radiographs to explore their potential application for surgical plan. Composited center of gravity had significant correlation and high similarity with center of gravity in T1–T10 segment. There was high collinearity between center of gravity points. The post-operative included angle between the gravity line and theoretic hip axis significantly decreased to nearly 0°. These findings demonstrate the MIMICS can reliably calculate the center of gravity in the upper trunk by a tissue separation method. The pre-operative included angle between the gravity line and theoretic hip axis was suggested as a parameter to improve surgical design for thoracolumbar kyphosis correction. • The gravity line should be considered as a composited result from many center of gravity points. • The center of gravity in the upper trunk can be reliably calculated by the tissue separation method. • Angle between the gravity line and theoretic hip axis may help thoracolumbar kyphosis correction. [ABSTRACT FROM AUTHOR]

Today, due to massive amount of information, NoSQL databases are used to compute complex data. These databases are used to store semi-structured and unstructured data for big data management. In this paper, fuzzy queries are executed by users on the information stored in the Neo4j graph database, which show results in defuzzy manner. To evaluate the efficiency of the proposed method, we considered a database of manufacturing company. Price and quality fuzzy variables were considered and used to define and execute the fuzzy queries. The results can verify the performance of the proposed method. Additionally, a counselor (who has information about the data) defines fuzzy terms, membership functions, and fuzzy rules table. The most important process in this method is to find the center of gravity in order to defuzzify the final result. So, an algorithm has been implemented for this purpose by C # programming language. The greatest query time is due to find center of gravity. The evaluation results show that the increase in query time by using the proposed approach in comparison to query time by using Cypher language is acceptable due to the complexity of fuzzy concepts. Therefore, the proposed solution will be suitable for using ambiguous and fuzzy queries in large databases. [ABSTRACT FROM AUTHOR]

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We construct the world's centres of gravity for human population, GDP and CO2 emissions by taking the best out of five recognised data sources covering the last two centuries. On the basis of a novel distortion‐free representation of these centres of gravity, we find a radical Western shift of GDP and CO2 emission centres in the nineteenth century, in sharp contrast with the stability of the demographic centre of gravity. Both GDP and emissions trends are reversed in the first half of the twentieth century, after World War I for CO2 emissions, after World War II for GDP. Since then, both centres are moving eastward at an accelerating speed. These patterns are perfectly consistent with the lead of Western countries starting the industrial revolution, the gradual replacement of coal by oil and gas as alternative sources of energy and the progressive catch‐up of Asian countries in the recent past. [ABSTRACT FROM AUTHOR]

Measuring the mass and Center of Gravity (CG) of rigid bodies with a multi-point weighing method is widely used nowadays. Traditional methods usually include two parts with a certain location, i.e., a fixed platform and a mobile platform. In this paper, a novel structure is proposed to adjust the mobile platform for eliminating side forces which may load on the load cells. In addition, closed-form equations are formulated to evaluate the performance of the structure, and transformation matrices are used to estimate the characteristics of the structure. Simulation results demonstrate that repeatability of the proposed structure is higher than the traditional one and there are no side forces. Moreover, the measurement results show that the relative error of mass was within 0.05%, and the error of CG was within ±0.3 mm. The structure presented in this paper provides a foundation for practical applications. [ABSTRACT FROM AUTHOR]

In this paper, we examine the concept of center of gravity and its relationship to the concept of possibilistic mean. We propose new transformations between the center of gravity and the possibilistic mean for triangular and trapezoidal fuzzy numbers. [ABSTRACT FROM AUTHOR]

Highlights • Using markerless motion capture system, the COG during sit-to-stand motion was measured. • The COG was compared with the measured value of marker-based motion capture system. • There were significant differences in COG displacement between system. • However, there was no difference in velocity and acceleration in the anteroposterior direction. Abstract Purpose In order to evaluate the movement strategy in sit-to-stand (STS) motion, it is necessary to measure the center of gravity (COG). However, there is no established method for enabling this using convenience device in the clinical setting. The purpose of this study was to validate the measurement of the COG during the STS motion using an inexpensive, portable and markerless motion capture system (MLS). Method Eighteen healthy adults participated in our study. The coordinates of the joint centers during the STS motion were collected using the Microsoft Kinect system (as a MLS) and the Vicon system (as a marker-based motion capture system [MBS]). The center of mass of each segment—which was calculated based on the segmental mass and length—were synthesized to calculate the COG. The displacement, velocity, acceleration of the COG during the STS motion were calculated from the data obtained using each system and compared between systems. Results The two systems showed significant difference in their measurements of displacement in both the vertical and anteroposterior directions. However, in the anteroposterior direction, there was no significant difference in the measurements of either velocity or acceleration. Conclusion Our results suggested the validity of the COG in the anteroposterior direction during the STS motion measured using the MLS. The method developed in the present study enables the evaluation of a patient's movement strategy. [ABSTRACT FROM AUTHOR]

Abstract Diffusion MRI-based probabilistic tractography is a powerful tool for non-invasively investigating normal brain architecture and alterations in structural connectivity associated with disease states. Both voxelwise and region-of-interest methods of analysis are capable of integrating population differences in tract amplitude (streamline count or density), given proper alignment of the tracts of interest. However, quantification of tract differences (between groups, or longitudinally within individuals) has been hampered by two related features of white matter. First, it is unknown to what extent healthy individuals differ in the precise location of white matter tracts, and to what extent experimental factors influence perceived tract location. Second, white matter lacks the gross neuroanatomical features (e.g., gyri, histological subtyping) that make parcellation of grey matter plausible – determining where tracts "should" lie within larger white matter structures is difficult. Accurately quantifying tractographic connectivity between individuals is thus inherently linked to the difficulty of identifying and aligning precise tract location. Tractography is often utilized to study neurological diseases in which the precise structural and connectivity abnormalities are unknown, underscoring the importance of accounting for individual differences in tract location when evaluating the strength of structural connectivity. We set out to quantify spatial variance in tracts aligned through a standard, whole-brain registration method, and to assess the impact of location mismatch on groupwise assessments of tract amplitude. We then developed a method for tract alignment that enhances the existing standard whole brain registration, and then tested whether this method improved the reliability of groupwise contrasts. Specifically, we conducted seed-based probabilistic diffusion tractography from primary motor, supplementary motor, and visual cortices, projecting through the corpus callosum. Streamline counts decreased rapidly with movement from the tract center (−35% per millimeter); tract misalignment of a few millimeters caused substantial compromise of amplitude comparisons. Alignment of tracts "peak-to-peak" is essential for accurate amplitude comparisons. However, for all transcallosal tracts registered through the whole-brain method, the mean separation distance between an individual subject's tract and the average tract (3.2 mm) precluded accurate comparison: at this separation, tract amplitudes were reduced by 74% from peak value. In contrast, alignment of subcortical tracts (thalamo-putaminal, pallido-rubral) was substantially better than alignment for cortical tracts; whole-brain registration was sufficient for these subcortical tracts. We demonstrated that location mismatches in cortical tractography were sufficient to produce false positive and false negative amplitude estimates in both groupwise and longitudinal comparisons. We then showed that our new tract alignment method substantially reduced location mismatch and improved both reliability and statistical power of subsequent quantitative comparisons. Highlights • Both location and amplitude are key when quantifying probabilistic tractography. • In callosal tracts, location mismatch reduces streamline density by up to 8.9-fold. • Mismatches in tract location compromise both voxelwise and groupwise comparisons. • Tract-to-tract registration reduces both false positive and false negative results. • Between-subjects variability in tract location explained 55% of tract mismatch. [ABSTRACT FROM AUTHOR]

We propose a horizontal-pendulum type thrust stand in which two-point acceleration measurement is applied to the null-balance method. The conventional displacement method was been applied to thrust measurement; thrust is determined by pendulum displacement which is caused by thrust. The null-balance method is also applied to the thrust measurement; a controller adjusts actuator force on the basis of pendulum displacement so as to null the pendulum displacement, and thrust is determined from actuator-driving current or voltage. However, both measurement methods can evaluate thrust variation up to one-third of the natural frequency that is determined by the configuration of the controller and pendulum. Hence, we proposed to apply acceleration measurement to the null-balance method, and showed that thrust variation could be measured up to 80 Hz. However, the proposed methods showed errors beyond 80 Hz; the error was caused by the translational flexibility of the torsional hinges. Then, we propose a new method that uses two-point acceleration measurement and adjustment of the center of gravity position to evaluate thrust variation beyond 80 Hz. The prototype evaluated thrust variation accurately beyond 200 Hz, although at 20-160 Hz, underestimating the amplitudes of reference thrust by 50 %. [ABSTRACT FROM AUTHOR]

Freestanding objects have endured seismic damage during major historical earthquakes, but their seismic performance is not fully understood yet. A steel frame was constructed with steel rods and moveable plates to investigate the effect of the center of gravity (CG) on the seismic response of nonstructural freestanding objects. The location of the CG can be tuned to change the CG in the frame. Two groups of shaking table tests were carried out using instrumented floor motion. To verify the shaking table test results, an analytical model was defined based on Housner's rocking model. The experimental response modes were predicted correctly. The experimental kinetic coefficient of friction obtained in the slow-pull tests agreed with the peak acceleration of the steel frame in the shaking table tests. The displacement amplitude generally decreased with increasing height of CG (h cg); however, this trend was not observed when the CG was fixed. Identical properties were observed for the rotational response of the frame. The experimental and analytical rocking responses were in agreement in terms of amplitude, but not in terms of time history and trajectories. The overturing criteria of overturing velocity, spectral velocity, and vulnerability, were evaluated using the experimental results. The overturning spectral acceleration was not accurately predicted using Housner's equation. The overturning probability and ratio were correctly predicted, and they increased with the increase in h cg. The findings of this work enable seismic risk mitigation of nonstructural freestanding objects. • A steel frame is fabricated which allows to tune the location of CG. • Shaking table tests are carried out using an instrumented floor motion. • The displacement amplitude generally decreases with increasing location of CG, h cg. • The experimental and analytical rocking amplitudes are in agreement. • The overturning probability and ratio increase with the increasing h cg. [ABSTRACT FROM AUTHOR]

In this research, linear programming is the chosen method for optimizing aircraft center of gravity. The method was tested on the Airbus A320 and Boeing 757 aircraft. In order to successfully accommodate the special company requests, certain modifications are applied. Formulation of the proposed method enables the use of real data for the passenger and cabin baggage weight, instead of statistical values which are commonly used. The proposed method is simple to use, modify, upgrade or apply in existing systems.

This paper addresses the center of gravity doctrine; this doctrine is applicable to some wars, at some moments, but not to all of them. Clausewitz predictedthis and stated that “in war the result is never final”. We argue that attacking one party’s center of gravity results in its defeat only when both adversaries apply the same strategy, namely the classic war. Today, finding the center of gravity is an integral part of the planning process.

This article presents a study of measures of center of gravity (COG) in phrase-final fricative epithesis (PFFE) produced by L1 and L2 speakers of Continental French (CF). Participants completed a reading task targeting 98 tokens of /i,y,u/ in phrase-final position. COG measures were taken at the 25%, 50% and 75% marks, normalized and submitted to a mixed linear regression. Results revealed that L2 speakers showed higher COG values than L1 speakers in low PFFE-to-vowel ratios at the 25%, 50%, and 75% marks. COG measures were then categorized into six profile types on the basis of their frequencies at each timepoint: flat–low, flat–high, rising, falling, rising–falling, and falling–rising. Counts of COG profile were then submitted to multinomial logistic regression. Results revealed that although L1 speakers produced predominantly flat–low profile types at lower percent devoicings, L2 speakers preferred multiple strategies involving higher levels of articulatory energy (rising, falling, rise–fall). These results suggest that while L1 speakers realize PFFE differently with respect to phonological context, L2 speakers rely on its most common allophone, strong frication, in most contexts. As such, the findings of this study argue for an additional phonetic dimension in the construct of L2 sociophonetic competence.

The center of mass of a given system is referred to as a position that is the average of all of its components. I am given two cases in which I need to find the center of mass for the problem of flipping over an incline. To solve the problem given, I utilize many equations that are derived to find the center of mass of both cases and then test each system when it is encountered with three different inclines increasing by fifteen degrees increments. The tests prove that the probability that a system will flip on an incline is due to many factors, the main of them being the height of the system, the area of support, as well as the weight of the system. This method of solving is not the most time-efficient one to find the center of mass and flipping probability; however, it does work and gives a viable solution.

Background:  It has already been demonstrated by previous studies that Baduanjin training can improve the body's balance. However, its biomechanical mechanism remains unknown. Center of gravity (COG) trajectory analysis is an essential biomechanical test to explore the balance ability of the human body. Previous studies have not used the COG trajectory analysis technique to research Baduanjin training. The study utilizes COG trajectory analysis to analyze the trajectory of COG during Baduanjin training and compare it with that of walking, which is a common exercise for improving balance and aerobic ability, to determine if Baduanjin exercises affect the COG more than walking., Materials and Methods:  Eight healthy female college students performed the walking and the eight forms of Baduanjin, a total of nine motions. The lower body kinematics were captured by the Vicon Motion Capture and Analysis System, while the kinetic data were acquired by the Kistler 3D Force Platform. The data were imported into Visual 3D to process the trajectory of the COG displacement amplitude, velocity, and acceleration of each motion. The COG horizontal envelope areas were calculated by Origin 9.0 Software (Origin Lab, Northampton, Massachusetts, USA) ., Results: Specific motions of Baduanjin provided significantly higher COG displacement amplitude, velocities, and acceleration training than walking. The F2 and F5 motions could provide a larger COG horizontal envelope area than walking. On the x-axis, F2 provided a greater COG displacement amplitude than walking, F1, F2, and F5 provided greater velocities, while all the motions provided greater accelerations. On the y-axis, all the motions except F2 provided greater COG displacement velocities and accelerations than walking. On the z-axis, F1-7 provided a greater COG displacement amplitude than walking, all the motions provided greater velocities, while all the motions except F2 provided greater accelerations., Conclusion: Baduanjin training provides a more intense COG perturbation than walking, which may be a more challenging balance training than walking., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Jiang et al.)

Abstract Dirty industries tend to relocate to regions with looser environmental regulations, thus turning those regions into pollution havens. Numerous studies have tested the pollution haven effect of inter-country industrial relocation. However, little attention has been paid to the effect that is hidden in domestic industry relocation. Considering that domestic investment is about 10-fold that of foreign investment, it is vital to examine this issue to ensure the achievability of China's international pledge of mitigating carbon emissions. This research integrated multiregional input-output analysis and a center of gravity model to visualize the dislocation between carbon emissions, value added, and outputs at a sectoral level from 2007 to 2012 in China. Carbon emissions were also decomposed to three segments of final demand. We also investigated the movement of the center of gravity of these segments, and their dislocation with the outputs. Our analysis found that more carbon emissions had relocated from east to west with domestic industry relocation, yet the opposite was found for value added. Specifically, carbon intensive sectors showed clear tendencies of shifting west. Capital formation was the major cause of the pollution haven effects for the economy as a whole. Thus, our results suggest that pollution haven effects exist in the relocation processes of most sectors. In turn, our findings support the idea that mitigation policies should differ by region and by industry. Our recommendations include a negative list for regions in the west, a mitigation policy for industries with high pollution, and differentiated supply chain management for final demands. Graphical abstract Image Highlights • MRIO and center of gravity are used to visualize the pollution haven effect. • Center of gravity is decomposed by final demand categories. • Most industries moving to the north and the west have pollution haven effect. • Capital formation is the major cause of pollution haven effect. [ABSTRACT FROM AUTHOR]

Abstract In this paper we show that for a Berger metric g ˆ on S 3 , the non-positively curved conformally compact Einstein metric on the 4-ball B 1 (0) with (S 3 , [ g ˆ ]) as its conformal infinity is unique up to isometries and it is the metric constructed by Pedersen [21]. In particular, since in [18] , we proved that if the Yamabe constant of the conformal infinity Y (S 3 , [ g ˆ ]) is close to that of the round sphere then any conformally compact Einstein manifold filled in must be negatively curved and simply connected, therefore if g ˆ is a Berger metric on S 3 with Y (S 3 , [ g ˆ ]) close to that of the round metric, the conformally compact Einstein metric filled in is unique up to isometries. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the CoG-FPOM, an adaptation of the Fuzzy Pay-Off Method (FPOM). The FPOM is a scenario-based real option valuation method that uses fuzzy numbers as possibility distributions. The paper shows that there are situations in which the original FPOM calculates the real option value to be negative, what is theoretically incorrect. The cause is related to the method used for obtaining a single representative value out of a fuzzy number. Instead of the possibilistic expected value operation used in the original FPOM, the CoG-FPOM uses the center of gravity (CoG) to accomplish the task – a proof of its general validity is presented. An application to calculate the abandonment real option for petroleum producing fields shows that the proposal can be easily used for project valuation under uncertainty. [ABSTRACT FROM AUTHOR]

Tropical cyclones (TC) prediction and intensity detection is one of the most emerging fields of research. Starting from Dvorak technique many approaches are used by meteorologist towards the TC intensity prediction and estimation. In this paper we have proposed an image processing based approach to categorise the cyclone intensity by using feature vector. The feature vector of a TC constructed using mean, variance, density and decentricity. Further, this vector converges to a distinct weight value by random weight genetic algorithm. Finally weight values under each intensity scale are used to find the intensity of a test image. This approach can be used in cyclone intensity detection technique. This paper focuses on estimate the intensity of tropical cyclones from satellite images over the Bay of Bengal. [ABSTRACT FROM AUTHOR]

Abstract We examines the movement trajectory of gravity centers of China's CO 2 emissions on a regional level based on a gravity model, and then investigate the impact of urbanization on CO 2 emissions by utilizing an extended Stochastic Impacts by Regression on Population, Affluence and Technology (STIRPAT) model under the change of gravity center. We measure the urbanization in different dimensions including both population and land urbanization. Besides, a panel data between 2005 and 2014 is used for our empirical estimation, and the Spatial Durbin Panel model is used for estimation. The results show that the movement trajectory of gravity centers as a whole moved towards the northwest over the period. With CO 2 emissions distribution presenting the characteristics of spatial agglomeration, we utilize the spatial econometric model to capture spatiality. The results show that the effect of population urbanization is insignificant; however, population urbanization has a positive and significant spatial spillover effect. Meanwhile, we find that the impact of land urbanization is significantly positive, while its spatial spillover effect is insignificant. Regarding other socioeconomic factors, it is proved that population scale, energy intensity and GDP per capita have a significantly positive impact, while industrialization level has a negative influence. These novel methodology and findings reveal that policy makers should carefully consider the characteristics of the rapid urbanization growth in China through the establishment of low-carbon urbanization policy standards, and strategies should emphasize China's land-use conditions and promote coordinate development between population urbanization and land urbanization to achieve the sustainable development of urbanization and a low-carbon economy. [ABSTRACT FROM AUTHOR]

Aim: To evaluate whether there is any developmental course of the shifting of the center of gravity (COG) in healthy preterm infants.Methods: Eleven healthy preterm infants were assessed on a computerized pedoscope from early preterm to term age. Data from the pedoscope and the videorecorder were analyzed with a special software for the assessment of the COG shifting. Infants were placed on the pedoscope in supine position for 5 min. We scored the positions of the COG during its shifting, the body parts most frequently involved in its shifting and the shifting' amplitude at each epoch. We scored the frequency of the COG shifting in head, trunk and bottom, its direction and amplitude using a semi-quantitative scale.Results: A developmental course of the COG shifting from preterm throughout post-term ages was demonstrated, with COG position displaced from head to bottom. The shifting amplitude decreased with increasing age. Lateral shifting were never observed.Interpretation: The developmental course of the COG shifting suggests the maturation of postural behaviour in healthy preterm infants. The displacement of the COG from head to bottom and the reduced amplitude of the COG shifting from preterm to post-term age indicates a more stable body position. [ABSTRACT FROM AUTHOR]

Background Patients with diabetes often develop diabetic peripheral neuropathy, which is a distal symmetric polyneuropathy, so foot function on the non-amputated side is expected to affect gait in vascular trans-tibial amputees. However, there is little information on the kinematics and kinetics of gait or the effects of diabetic peripheral neuropathy in vascular trans-tibial amputees. This study aimed to clarify these effects, including the biomechanics of the ankle on the non-amputated side. Methods Participants were 10 vascular trans-tibial amputees with diabetic peripheral neuropathy (group V) and 8 traumatic trans-tibial amputees (group T). Each subject's gait was analyzed at a self-selected speed using a three-dimensional motion analyzer and force plates. Findings Ankle plantarflexion angle, heel elevation angle, and peak and impulse of anterior ground reaction force were smaller on the non-amputated side during pre-swing in group V than in group T. Center of gravity during pre-swing on the non-amputated side was lower in group V than in group T. Hip extension torque during loading response on the prosthetic side was greater in group V than in group T. Interpretation These findings suggest that the biomechanical function of the ankle on the non-amputated side during pre-swing is poorer in vascular trans-tibial amputees with DPN than in traumatic trans-tibial amputees; the height of the center of gravity could not be maintained during this phase in vascular trans-tibial amputees with diabetic peripheral neuropathy. The hip joint on the prosthetic side compensated for this diminished function at the ankle during loading response. [ABSTRACT FROM AUTHOR]

Formulas for calculating deformation and strain moduli using experimental tensile deformation diagrams of a steel-fiber-reinforced concrete are derived. The block diagram of a nonlinear iterative calculation, which previously have never been shown in the literature, is presented. Results of the calculation are tabulated. The opening of cracks and deflection of a bent element are also calculated, and the results are compared with those found based on limiting states. [ABSTRACT FROM AUTHOR]

Balance changes during pregnancy likely occur because of mass gains and mass distribution changes. However, to date there is no way of tracking balance through center of mass motion because no method is available to identify of the body center of mass throughout pregnancy. We compared methods for determining segment masses and torso center of mass location. The availability of a method for tracking these changes during pregnancy will make determining balance changes through center of mass motion an option for future pregnancy balance research. Thirty pregnant women from eight weeks gestation until birth were recruited for monthly anthropometric measurements, motion capture analysis of body segment locations, and force plate analysis of center of pressure during quiet standing and supine laying. From these measurements, we were able to compare regression, volume measurement, and weighted sum methods to calculate body center of mass throughout pregnancy. We found that mass changes around the trunk were most prevalent as expected, but mass changes throughout the body (especially the thighs) were also seen. Our findings also suggest that a series of anthropometric measurements first suggested by Pavol et al. (2002), in combination with quiet standing on a force plate, can be used to identify the needed components (segment masses and torso center of mass location in three dimensions) to calculate body center of mass changes during pregnancy. The results of this study will make tracking of center of mass motion a possibility for future pregnancy balance research. [ABSTRACT FROM AUTHOR]

Background/Objectives: Balance is the ability to stabilize the body and maintain static and dynamic posture control, and failure to maintain balance increases the risk of falls; therefore, evaluating balance ability has been used to predict the risk of falling. This study aimed to investigate the efficacy of tracking moving target test with center of gravity(COG) as a predictive factor of falls. Methods: This study was conducted at an elderly welfare center in Seoul and the participants were aged 65 years or older. Success rate in tracking moving target was measured by using a newly developed Fall Risk Assessment (FRA) device (InBody Co®) and fall rates for 6 months were evaluated by telephone survey. Results: In the univariate analysis, the proportion of subjects experiencing falls was significantly lower with increasing success rate in tracking moving target in the left-right and diagonal B directions (p=0.0017, p=0.0203, respectively). In the left-right direction, relative to quartile 1 of success rate in tracking moving target, adjusted ORs of falling for the six-months for quartiles 2, 3, and 4 decreased to 0.36, 0.28, and 0.11, respectively (p=0.015). Conclusions: Success rate in tracking moving target in the diagonal B directions was not a significant predictor of falling after controlling the confounding variables of age, sex, current smoking status, alcohol drinking, physical activity, BMI, and histories of falling and chronic diseases, and sleeping disorders. Therefore, success rate in tracking moving target in the left-right direction well predicted a lower six-month fall rate. This demonstrates the potential efficacy of tracking moving target test in the left-right direction as a predictive factor for fall risk. [ABSTRACT FROM AUTHOR]

The purpose of the present work is to construct a reaction board based on fiber Bragg gratings (FBGs) that could be used for estimation of the 2D coordinates of the projection of center of gravity (CG) of an object. The apparatus is consisted of a rigid equilateral triangular board mounted on three supports at the vertices, two of which have cantilevers instrumented with FBGs. When an object of known weight is placed on the board, the bending strain of the cantilevers is measured by a proportional wavelength shift of the FBGs. Applying the equilibrium conditions of a rigid body and proper calibration procedures, the wavelength shift is used to estimate the vertical reaction forces and moments of force at the supports and the coordinates of the object's CG projection on the board. This method can be used on a regular basis to estimate the CG of the human body or objects with complex geometry and density distribution. An example is provided for the estimation of the CG projection coordinates of two orthopaedic femur bone models, one intact, and the other with a hip stem implant encased. The clinical implications of changing the normal CG location by means of a prosthesis have been discussed. [ABSTRACT FROM AUTHOR]