The aim of this study was to produce a simple and inexpensive technique for estimating the obturator foramen area (OFA) from young calves based on the hypothesis that OFA can be extrapolated from simple linear measurements. Three linear measurements - dorsoventral height, craneocaudal width and total perimeter of obturator foramen - were obtained from 55 bovine hemicoxae. Different algorithms for determining OFA were then produced with a regression analysis (curve fitting) and statistical analysis software. The most simple equation was OFA (mm2) = [3,150.538 + (36.111*CW)] - [147,856.033/DH] (where CW = craneocaudal width and DH = dorsoventral height, both in mm), representing a good nonlinear model with a standard deviation of error for the estimate of 232.44 and a coefficient of multiple determination of 0.846. This formula may be helpful as a repeatable and easily performed estimation of the obturator foramen area in young bovines. The area of the obturator foramen magnum can thus be estimated using this regression formula.
Biometry ; Foramen Magnum ; Nonlinear Dynamics ; Osteology

A modelling scheme for the stress analysis taking into account load transfer characteristics of the osseointegrated interfaces between dental implant and surrounding alveolar bone was investigated. Main aim was to develop a more realistic simulation methodology for the load transfer at the interfaces than the prefect bonding assumption at the interfaces which might end up the reduced level in the stress result. In the present study, characteristics of osseointegrated bone/implant interfaces was modelled with material nonlinearity assumption. Bones at the interface were given different stiffness properties as functions of stresses. Six different models, i.e. tens0, tens20, tens40, tens60, tens80, and tens100 of which the tensile moduli of the bones forming the bone/implant interfaces were specified from 0, 20, 40, 60, 80, and 100 percents, respectively, of the compressive modulus were analysed. Comparisons between each model were made to study the effect of the tensile load carrying abilities, i.e. the effectivity of load transfer, of interfacial bones on the stress distribution. Results of the present study showed significant differences in the bone stresses across the interfaces. The peak stresses, however, were virtually the same regardless of the difference in the effectivity of load transfer, indicating the conventional linear modelling scheme which assumes perfect bonding at the bone/implant interface can be used without causing significant errors in the stress levels.
Dental Implants* ; Lifting ; Linear Models ; Nonlinear Dynamics*

The use of non-invasive blood glucose detection techniques can help diabetic patients to alleviate the pain of intrusive detection, reduce the cost of detection, and achieve real-time monitoring and effective control of blood glucose. Given the existing limitations of the minimally invasive or invasive blood glucose detection methods, such as low detection accuracy, high cost and complex operation, and the laser source's wavelength and cost, this paper, based on the non-invasive blood glucose detector developed by the research group, designs a non-invasive blood glucose detection method. It is founded on dual-wavelength near-infrared light diffuse reflection by using the 1 550 nm near-infrared light as measuring light to collect blood glucose information and the 1 310 nm near-infrared light as reference light to remove the effects of water molecules in the blood. Fourteen volunteers were recruited for
Blood Glucose ; Diabetes Mellitus ; Humans ; Nonlinear Dynamics

Edema is a common pathological symptom, but its development mechanism is unknown. Based on the bearings of pressure upon interstitium structure and substantial exchange between plasma and interstitial fluid, a dymamics model describing the development of edema was set up. The model's theoretical results showed that the variations of interstitium pressure and structure due to imbalance of substantial exchange may lead to the development of edema, which is in accordance with recent clinical researches. Discussions on the dynamic mechanism of the development of edema proposed that the best way to prevent edema is instituting treatment before the interstitial structure being destroyed.
Edema ; physiopathology ; Humans ; Models, Biological ; Nonlinear Dynamics

A new mathematical equation characterizing the compression of pharmaceutical materials is presented. This equation presumed that the rate of change of the compressible volume of powder with respect to the pressure is proportional to the compressible volume. The new model provided a good fit to several model substances employing non-linear regression techniques. The validity of the model had been verified with experimental results of various pharmaceutical powders according to the Akaikes informatics criterion (AIC) and the sum of squared deviations (SS). The parameter of the new model might reflect quantitatively the fundamental compression behaviors of the powders. It had demonstrated that the proposed model could well predict the compaction characteristics of solid particles like the Kawakita model.
Compressive Strength ; Nonlinear Dynamics ; Powders ; chemistry ; Pressure

OBJECTIVES: Load carrying tasks are recognized as one of the primary occupational factors leading to slip and fall injuries. Nevertheless, the mechanisms associated with load carrying and walking stability remain illusive. The objective of the current study was to apply local dynamic stability measure in walking while carrying a load, and to investigate the possible adaptive gait stability changes. METHODS: Current study involved 25 young adults in a biomechanics research laboratory. One tri-axial accelerometer was used to measure three-dimensional low back acceleration during continuous treadmill walking. Local dynamic stability was quantified by the maximum Lyapunov exponent (maxLE) from a nonlinear dynamics approach. RESULTS: Long term maxLE was found to be significant higher under load condition than no-load condition in all three reference axes, indicating the declined local dynamic stability associated with load carrying. CONCLUSION: Current study confirmed the sensitivity of local dynamic stability measure in load carrying situation. It was concluded that load carrying tasks were associated with declined local dynamic stability, which may result in increased risk of fall accident. This finding has implications in preventing fall accidents associated with occupational load carrying.
Acceleration ; Biomechanics ; Gait ; Humans ; Lifting ; Nonlinear Dynamics ; Walking ; Young Adult

BACKGROUND: The aim of this study was to investigate the underlying changes in heart rate variability (HRV) of preoperative diabetic patients using five analytical methods; SDNN (standard deviation of normal to normal intervals), SDANN (standard deviation of the mean of normal RR intervals for each 5 min period of the entire electrocardiographic recording), RMSSD (root mean square successive difference, the squre root of the mean of the sum of the squares of differences between adjacent normal RR intervals over the entire electrocardiographic recording), PNN50 (percent of difference between adjacent normal RR intervals that are greater than 50 ms computed over the entire electrocardiographic recording) for linear time domain analysis and approximate entropy for nonlinear complexity analysis. METHODS: HRV values analyzed by five different measures were compared between a control group of ten nondiabetics without any significant systemic disease and a diabetic group of ten patients from the preoperative ambulatory electrocardiographic recordings. RESULTS: Approximate entropy, SDNN and SDANN values were significantly lower in the diabetic group than those of the control group (P< 0.01). CONCLUSIONS: Significantly decreased approximate entropy, SDNN and SDANN could provide information about decreased cardiovascular complexity and sympathetic output, suggesting the nature of dysfunction of the diabetic cardiovascular system.
Cardiovascular System ; Electrocardiography ; Entropy ; Heart Rate* ; Heart* ; Humans ; Nonlinear Dynamics*

OBJECT: It seemed worthwhile to estimate nonlinear measures of the electroencephalogram (EEG) in schizophrenic patients, because nonlinear measures might serve as indicators of the specific brain function in schizophrenia. METHOD: Previous studies which estimated the chaoticity in the brain of schizophrenia with nonlinear methods recorded the EEGs at limited electrodes, so we tried to record EEGs from 16 channels for nonlinear analysis in 19 patients with Schizophrenia and 8 healthy control subjects. We employed a new method to calculate the nonlinear invariant measures. For limited noisy data, this algorithm was strikingly faster and more accurate than previous ones. RESULTS: Our results showed that the schizophrenic patients had lower values of the largest positive Lyapunov exponent at the left inferior frontal and anterior temporal head regions compared with normal controls. CONCLUSIONS: These results suggest that the nonlinear analysis of the EEGs such as the estimation of the largest positive Lyapunov exponent seems to be a useful tool in analyzing EEG data to explore the neurodynamics of the brain of schizophrenic patients.
Brain ; Electrodes ; Electroencephalography* ; Head ; Humans ; Nonlinear Dynamics* ; Schizophrenia*

In recent years, exploring the physiological and pathological mechanisms of brain functional integration from the neural network level has become one of the focuses of neuroscience research. Due to the non-stationary and nonlinear characteristics of neural signals, its linear characteristics are not sufficient to fully explain the potential neurophysiological activity mechanism in the implementation of complex brain functions. In order to overcome the limitation that the linear algorithm cannot effectively analyze the nonlinear characteristics of signals, researchers proposed the transfer entropy (TE) algorithm. In recent years, with the introduction of the concept of brain functional network, TE has been continuously optimized as a powerful tool for nonlinear time series multivariate analysis. This paper first introduces the principle of TE algorithm and the research progress of related improved algorithms, discusses and compares their respective characteristics, and then summarizes the application of TE algorithm in the field of electrophysiological signal analysis. Finally, combined with the research progress in recent years, the existing problems of TE are discussed, and the future development direction is prospected.
Algorithms ; Brain/physiology* ; Entropy ; Neural Networks, Computer ; Nonlinear Dynamics

The changes of electroencephalogram(EEG) in patients with dementia of Alzheimer's type are most commonly studied by analyzing power or magnitude in traditionally defined frequency bands. However because of the absence of an identified metric which quantifies the complex amount of information, there are many limitations in using such a linear method. According to the chaos theory, irregular signals of EEG can be also resulted from low dimensional deterministic chaos. Chaotic nonlinear dynamics in the EEG can be studied by calculating the largest Lyapunov exponent(L1). The authors have analyzed EEG epochs from three patients with dementia of Alzheimer's type and three matched control subjects. The largest L1 is calculated from EEG epochs consisting of 16.384 data points per channel in 15 channels. The results showed that patients with dementia of Alzheimer's type had significantly lower L1 than non-demented controls on 8 channels. Topographic analysis showed that the L1 were significantly lower in patients with Alzheimer's disease on all the frontal, temporal, central, and occipital head regions. These results show that brains of patients with dementia of Alzheimer's type have a decreased chaotic quality of electrophysiological behavior. We conclude that the nonlinear analysis such as calculating the L1 can be a promising tool for detecting relative changes in the complexity of brain dynamics.
Alzheimer Disease ; Brain ; Dementia* ; Electroencephalography* ; Head ; Humans ; Nonlinear Dynamics*