Masticatory robots have a broad application prospect in the field of denture material tests and mandible rehabilitation. Mechanism type of temporomandibular joint structure is an important factor influencing the performance of the masticatory robot. In view of the wide application of elastic components in the field of the biomimetic robot, an elastic component was adopted to simulate the buffering characteristics of the temporomandibular joint disc and formed the elastic temporomandibular joint structure on the basis of point-contact high pair. Secondly, the influences of the elastic temporomandibular joint structure (on mechanism degree, kinematics, dynamics, etc.) were discussed. The position and velocity of the temporomandibular joint were analyzed based on geometric constraints of the joint surface, and the dynamic analysis based on the Lagrange equation was carried out. Finally, the influence of the preload and stiffness of the elastic component was analyzed by the response surface method. The results showed that the elastic temporomandibular joint structure could effectively guarantee the flexible movement and stable force of the joint. The elastic joint structure proposed in this paper further improves the biomimetic behavior of masticatory robots. It provides new ideas for the biomimetic design of viscoelastic joint discs.
Signal classification is a key of brain-computer interface (BCI). In this paper, we present a new method for classifying the electroencephalogram (EEG) signals of which the features are heterogeneous. This method is called wrapped elastic net feature selection and classification. Firstly, we used the joint application of time-domain statistic, power spectral density (PSD), common spatial pattern (CSP) and autoregressive (AR) model to extract high-dimensional fused features of the preprocessed EEG signals. Then we used the wrapped method for feature selection. We fitted the logistic regression model penalized with elastic net on the training data, and obtained the parameter estimation by coordinate descent method. Then we selected best feature subset by using 10-fold cross-validation. Finally, we classified the test sample using the trained model. Data used in the experiment were the EEG data from international BCI Competition Ⅳ. The results showed that the method proposed was suitable for fused feature selection with high-dimension. For identifying EEG signals, it is more effective and faster, and can single out a more relevant subset to obtain a relatively simple model. The average test accuracy reached 81.78%.
Bl factor is a key system parameter of the resonant blood viscoelastic sensor. In this paper, a dynamic measurement system for the spatial distribution of Bl factor based on velocity amplitude and motional impedance was designed. The system extracted the velocity amplitude and motional impedance of the coil under the dynamic condition of driving the sensor to generate simple harmonic oscillations using laser displacement and impedance analysis combined with in-phase/quadrature demodulation algorithm, and controlled the equilibrium position of the coil by adjusting the direct current component of the excitation current to realize the position scanning. In the position interval of [?240, 240] μm, the maximum coefficient of variation of the measurement results was 0.077 3%, and the maximum relative error to the simulation results was 2.937 9%, with a linear fitting correlation coefficient R2 = 0.996 8. The system can be used to accurately measure the spatial distribution of Bl factor of the resonant blood viscoelastic sensor, which provides a technical support for the verification of the design of the sensor magnetic circuit.
Erythemato-squamous diseases are a general designation of six common skin diseases, of which the differential diagnosis is a difficult problem in dermatology. This paper presents a new method based on virtual coding for qualitative variables and multinomial logistic regression penalized via elastic net. Considering the attributes of variables, a virtual coding is applied and contributes to avoid the irrationality of calculating nominal values directly. Multinomial logistic regression model penalized via elastic net is thence used to fit the correlation between the features and classification of diseases. At last, parameter estimations can be attained through coordinate descent. This method reached accuracy rate of 98.34%±0.0027% using 10-fold cross validation in the experiments. Our method attained equivalent accuracy rate compared to the results of other methods, but steps are simpler and stability is higher.
In order to understand how the biomechanical properties of rabbit cornea change over time after corneal ablation, 21 healthy adult rabbits were used in this study, with the left eye as experimental side and the right eye as the control side. Firstly, a lamellar knife was used to remove a portion of the anterior corneal surface tissue (30%~50% of the original corneal thickness) from the left eye of each rabbit, as an animal model simulating corneal refractive surgery. Secondly, postoperative experimental rabbits were kept for one, three, or six months until being euthanized. Strip specimens were produced using their corneas in vitro to perform a uniaxial tensile test with an average loading-unloading rate of approximately 0.16 mm/s. Finally, the visco-hyperelastic material constitutive model was used to fit the data. The results showed that there was a significant difference in the viscoelastic parameters of the corneas between the experimental and the control eyes at the first and third postoperative months. There was a difference in tangential modulus between the experimental and the control eyes at strain levels of 0.02 and 0.05 at the third postoperative month. There was no significant difference in biomechanical parameters between the experimental and the control eyes at the sixth postoperative month. These results indicate that compared with the control eyes, the biomechanical properties of the experimental eyes vary over postoperative time. At the third postoperative month, the ratio of corneal tangential modulus between the experimental and the control eyes significantly increased, and then decreased. This work lays a preliminary foundation for understanding the biomechanical properties of the cornea after corneal refractive surgery based on rapid testing data obtained clinically.
Objective To re-estimate price elasticity of different income groups’ demand for cigarette in terms of the lastest national tobacco consumption data and provide policy-makers with evidence to make decision on public policy of tobacco control. Methods A total of 16 056 adults of different income were surveyed in 27 provinces in 2002 and the data analyzed by using two-part model (logistic and log-linear model). Results We found that the demand elasticities were -0.589, -0.234, -0.017 and 0.247 for the poor group, low income group, middle income group and high income group, respectively. Conclusions Increasing tobacco tax will result in decreasing more cigarette consumption of lower income groups than higher groups, bearing more taxation of higher income groups than lower income groups, therefore tobacco taxation is not regressive.
Objective
To compare the effectiveness of titanium elastic nail (TEN) and locking compression plate fixation in treating femoral subtrochanteric fracture in older children.
Methods
Between April 2015 and September 2016, 35 older children (aged 7-13 years) with femoral subtrochanteric fractures were treated, the clinical data were retrospectively reviewed. TEN fixation was used in 19 cases (group A) and locking compression plate fixation in 16 cases (group B). There was no significant difference in age, gender, sides, fracture causes, type of fracture, and time from injury to operation between 2 groups (P>0.05). The fluoroscopy times, operation time, intraoperative blood loss, fracture healing time were recorded and compared between 2 groups. The limb function was evaluated according to the Sanders scores and Flynnet al. outcome score.
Results
All the patients were followed up 6-24 months (mean, 11.46 months). The operation time, intraoperative blood loss, and fracture healing time of group A were significantly less than those of group B, but the fluoroscopy times of group A was significantly more than that of group B (P<0.05). All the fractures were healed, no breakage of screw, infection of deep tissue, nerve injury, osteonecrosis of the femoral head, or other complication occurred. At last follow-up, according to the Sanders scores, the results were excellent in 14 cases, good in 4 cases, and fair in 1 case in group A with an excellent and good rate of 94.74%; the results were excellent in 12 cases, good in 3 cases, and fair in 1 case in group B with an excellent and good rate of 93.75%; showing no significant difference between 2 groups (χ2=0.400, P=0.980). According to the Flynn et al. outcome score, the results were excellent in 13 cases, good in 5 cases, and fair in 1 case in group A with an excellent and good rate of 94.74%; the results were excellent in 11 cases, good in 3 cases, and fair in 2 cases in group B with an excellent and good rate of 87.50%; showing no significant difference between 2 groups (χ2=0.748, P=0.688).
Conclusion
Both TEN and locking compression plate have satisfactory outcomes for treating pediatric femoral subtrochanteric fractures. TEN method has minimally trauma, security, and faster fracture healing when compared with locking compression plate.
Objective
To investigate the elasticity of demand for health care services in China, and to provide suggestions for further studies.
Methods
Databases including PubMed, The Cochrane Library (Issue 10, 2015), EMbase, CNKI, VIP and WanFang Data were searched from inception to December 2015 to collect studies about price elasticity or income elasticity of demand for health care services. Literatures were screened and related information was independently extracted by two reviewers. Then qualitative approaches were applied to describe the elasticity.
Results
A total of 31 studies were included. Estimates of the own-price elasticity of demand for health care services ranged from –2.520 to 2.944 in 25 studies; 2 studies estimated cross-price elasticity between outpatient and inpatient service and one study estimated cross-price elasticity between different levels of inpatient services and all estimates were positive; Estimates of the income elasticity ranged from –0.020 to 2.480 in 28 studies. Demand for inpatient services was more income sensitive than the demand for outpatient services and urban citizens were more sensitive to income than their rural counterparts.
Conclusion
Health service is insensitive to price and belongs to necessity; inpatient service and outpatient service are substitutes for each other and different levels of inpatient services are substitutes for each other; government are supposed to tackle with the unbalanced increase of the demand of outpatient and inpatient services along with the increase of income to guide rational health-seeking behaviors.
This study was aimed to compare the mechanical characteristics under different physiological load conditions with three-dimensional finite element model of rigid fixation and elastic fixation in the lumbar. We observed the stress distribution characteristics of a sample of healthy male volunteer modeling under vertical, flexion and extension torque situation. The outcomes showed that there existed 4-6 times pressure on the connecting rod of rigid fixation compared with the elastic fixations under different loads, and the stress peak and area of force on elastic fixation were much higher than that of the rigid fixations. The elastic fixation has more biomechanical advantages than rigid fixation in promoting interbody lumbar fusion after surgery.
Objective
To evaluate the short-term effectiveness of Kirschner wire (K-wire) elastic fixation in the treatment of Doyle type Ⅰ and Ⅱ mallet finger.
Methods
Between July 2016 and March 2017, 18 patients with Doyle type Ⅰ and Ⅱ mallet finger were treated. There were 12 males and 6 males, with an average age of 45 years (range, 16-61 years). The index finger was involved in 2 cases, the middle finger in 3 cases, the ring finger in 10 cases, and the little finger in 3 cases. The interval from injury to operation ranged from 2 hours to 45 days (median, 5.5 hours). There were 8 patients of closed wound and 10 patients of open wound. Fourteen patients were simply extensor tendon rupture and 4 were extensor tendon rupture complicated with avulsion fracture. The distal interphalangeal joints (DIPJ) of injured fingers were elastically fixed with the K-wire at mild dorsal extend position. The K-wire was removed after 6 weeks, and the functional training started.
Results
The operation time was 34-53 minutes (mean, 38.9 minutes). Patients were followed up 3-8 months (mean, 5 months). All incisions healed primarily and no K-wire loosening or infection happened during the period of fixation. All mallet fingers were corrected. The range of motion (ROM) in terms of active flexion of injured DIPJ was (75.83±11.15)° at 6 weeks after operation, showing significant difference when compared with the normal DIPJ of contralateral finger [(85.28±6.06)°] (t=3.158, P=0.003). The ROM in terms of active flexion was (82.67±6.78)° in 15 patients who were followed up at 8 months after operation, showing no significant difference when compared with the normal DIPJ of contralateral finger [(86.00±5.73)°] (t=1.454, P=0.157). After the removal of K-wire at 6 weeks, visual analogue scale (VAS) score of active flexion and of passive flexion to maximum angle were 1.78±0.88 and 3.06±1.06, respectively. According to the total active motion criteria, the effectiveness was rated as excellent in 10 cases, good in 5 cases, moderate in 2 cases, and poor in 1 case, and the excellent and good rate was 83.33%. The patients’ satisfaction were accessed by Likert scale, which were 3-5 (mean, 4.2).
Conclusion
K-wire elastic fixation in the treatment of Doyle typeⅠand Ⅱ mallet finger can repair the extensor effectively, correct the mallet finger deformity, and also be benefit for the flexion-extension function restoration of DIPJ.
