Biomedical subjects

Guangzhi Wang

Publications and source records attributed to Guangzhi Wang.

7 recordsLinked to original sources

PubMed2005

[A study of gait recognition based on kinematics and kinetics parameters].

In order to recognize people by their gait, we propose a pattern recognizing method based on kinematics and kinetics parameters. The feature extraction methods of joint angle and vertical ground reaction force (VGRF) were given. 14 healthy male subjects participated in this experiment. The experimental results showed that the correct classification rates (CCR) was 87.1% at k = 1 and 90% at k = 3 (k-nearest neighbor) based on joint angle recognition; the CCR was 85.7% at k = 1 and 80% at k = 3 based on VGRF recognition. The multivariate analysis of the experimental data proved the feasibility of gait recognition. The principal component analysis and curves of VGRF also showed that the instant of foot strike plays an important role in gait recognition.

Adult↗

PubMed2005

[The frequency features and application of edge detection differential operators in medical image].

Edge detection is an absolutely necessary step in medical image processing, and the use of differential operators to detect edge is one of the most common and effective methods. In this paper are analyzed the frequency features of the Roberts operator, Prewitt operator, Sobel operator and Laplacian operator from the viewpoint of frequency domain, and it is proposed that the frequency features of the differential operators should be considered when differential operator is being used and/or constructed. Because edge detection operator is sensitive to the edge type, the appropriate operator should be adopted in different edge type detection. Finally, the importance and necessity of selecting edge detection operator are validated in the MRI image edge processing.

Algorithms↗

PubMed2005

[Algorithm for recognizing the markers in human motion detection].

An algorithm for recognizing the markers in human motion detection is proposed in this paper. It includes three parts as follows: (1) an improved template matching method is used to acuminate the peak of the matching result. (2) The weighted average of the cross correlation between target image and template is given in order to make the resolution increase to sub-pixel level. (3) Forecasting the motion of marker and overcoming the hiding of marker are realized basing on the continuity of human motion. The result of experiments shows that the algorithm can recognize the positions of the markers at a relatively higher accuracy and speed. A gait analysis system based on this algorithm has come into use.

Algorithms↗

PubMed2004

Assessment of the hypoxic-ischemic encephalopathy in neonates using non-invasive near-infrared spectroscopy.

This paper introduces a method of monitoring cerebral oxygenation for healthy neonates and neonates with hypoxic-ischemic encephalopathy (HIE) using near-infrared spectroscopy. The object of this study was to investigate whether or not there were differences between the HIE group and the healthy group in terms of NIRS parameters. The subjects were all term neonates, their age ranging from 2 to 18 days. The healthy group included 25 subjects while the HIE group consisted of 16 patients. A prototype NIRS instrument, which provides the data of tissue oxygenation including regional oxygen saturation (rSO2), the increment of oxyhemoglobin concentration and hemoglobin (deltaHbO2 and deltaHb) was used, and the data of rSO2 was compared with the data from the blood gas analyzer. The result shows that: (1) the mean+/-SD of rSO2 for the healthy group was 62 +/- 4% in the frontal region under the quiet sleep condition, but the mean+/-SD of rSO2 for the HIE group was 53 +/- 3%. (2) As all subjects inhaled pure oxygen in 21 min(-1) for a period of 60 s, rSO2 for the healthy group increased rapidly, with the increase in rSO2 (deltarSO2) being 7 +/- 2.3%, but the increase in rSO2 for the HIE neonates was 3 +/- 1.5%. After inhaling oxygen, deltaHbO2 and deltaHb between the two groups were also significantly different. (3) During all the experiments SpO2 was monitored, the value of SpO2 was not significantly different between the two groups. The above observations suggest that the rSO2 in quiet condition and the values of change of rSO2, HbO2 and Hb during the inhalation of oxygen may be used as the parameters to discover and assess the HIE infants.

Algorithms↗

PubMed2004

In vivo and noninvasive three-dimensional patellar tracking induced by individual heads of quadriceps.

PURPOSE: Unbalanced actions of the quadriceps components are closely linked to patellar mal-tracking and patellofemoral pain syndrome. However, it is not clear how individual quadriceps components pull and rotate the patella three dimensionally. The purpose of this study was to investigate in vivo and noninvasively patellar tracking induced by individual quadriceps components. METHODS: Individual quadriceps component was activated selectively through electrical stimulation at the muscle motor point, and the resulting patellar tracking was measured in vivo and noninvasively in 18 knees of 12 subjects. The in vivo and noninvasively patellar tracking was corroborated with in vivo fluoroscopy and in vitro cadaver measurements. RESULTS: Vastus medialis (VM) mainly pulled the patella first in the medial and second in the proximal directions and vastus lateralis (VL) pulled first in the proximal and second in the lateral directions. The oblique portion (VMO) of the VM pulled the patella mainly medially and the longus portion (VML) more proximally. Medial tilt was the major patellar rotation induced by VMO contraction at full knee extension. With the knee at the more flexed positions, the amplitude of patellar movement induced by comparable quadriceps contractions was reduced significantly compared to that at full knee extension, and VMO changed its main action from extending to flexing the patella. CONCLUSIONS: The medial and lateral quadriceps components moved the patella in rather different directions, and rotated the patella differently about the mediolateral tilt and mediolateral rotation axes but similarly in extension. The approach can be used to investigate patellar tracking in vivo and noninvasively in both healthy subjects and patients with patellofemoral disorder and patellar malalignment.

Adult↗

PubMed2003

In vivo load sharing among the quadriceps components.

Knee extension is always performed with coordinated contractions of multiple quadriceps muscle components; however, how the load is shared among them under normal and pathological conditions is unclear. We hypothesized that: the absolute moment generated by each quadriceps component increases with the total knee extension moment; the relative contribution and its dependence on the total knee extension moment are different for different quadriceps components; and the centrally located large vastus intermedius (VI) is favored by the central nervous system at low levels of activation. Electrical stimulation was used to activate each quadriceps component selectively in six human subjects. The relationship between the knee extension moment generated by an individual quadriceps component and the corresponding compound muscular action potential (M-wave) over various contraction levels was established for each quadriceps component. This relationship was used to calibrate the corresponding EMG signal and determine load sharing among quadriceps components during submaximal isometric voluntary knee extension. The VI contributed the most (51.8-39.6%) and vastus medialis the least (9.5-12.2%) to knee extension moment (P<0.05). As the knee extension moment increased, the relative contribution of the VI decreased (P=0.017) while the relation contribution of the vastus lateralis and medialis increased (P</=0.012). The absolute moment generated by each quadriceps component always increased with the total knee extension moment (P<0.002). Our in vivo approach determined subject- and condition-specific load sharing among individual muscles and showed that the central nervous system utilized the centrally located, uniarticular VI in submaximal isometric knee extension.

Adult↗

PubMed2003

[Antidepressant effect of ethanol extracts from three species of sect. Hypericum medicinal plants in mice].

OBJECTIVE: To explore the antidepressant actions of ethanol extracts from three species of sect. Hypericum medicinal plants. METHODS: The forced swimming test and mouse tail suspensions in mice were used. RESULT: Ethanol extracts of sect. Hypericum medicinal plants significantly shortened motionless time of mice forced swimming and despair time of mouse tail suspension in the two behavior despair animal models of depression. The effect of H. faberi was weaker than that of H. perforatum. CONCLUSION: These findings demonstrated that the extracts from three species of sect. Hypericum medicinal plants possessed obvious antidepressant activity.

Animals↗