Search

Background & purposeObesity and metabolic disorders were associated with increased risk of MM, a disease characterized by high risk of relapsing and require frequent hospitalizations. In this study, we conducted a retrospective cohort study to explore the association of metabolic obesity phenotypes with the readmission risk of MM.Patients & methodsWe analyzed 34,852 patients diagnosed with MM from the Nationwide Readmissions Database (NRD), a nationally representative database from US. Hospitalization diagnosis of patients were obtained using ICD-10 diagnosis codes. According to obesity and metabolic status, the population was divided into four phenotypes: metabolically healthy non-obese (MHNO), metabolically unhealthy non-obese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO). The patients with different phenotypes were observed for hospital readmission at days 30-day, 60-day, 90-day and 180-day. Multivariate cox regression model was used to estimate the relationship between obesity metabolic phenotypes and readmissions risk.ResultsThere were 5,400 (15.5%), 7,255 (22.4%), 8,025 (27.0%) and 7,839 (35.6%) unplanned readmissions within 30-day, 60-day, 90-day and 180-day follow-up, respectively. For 90-day and 180-day follow-up, compared with patients with the MHNO phenotype, those with metabolic unhealthy phenotypes MUNO (90-day: P = 0.004; 180-day: P = < 0.001) and MUO (90-day: P = 0.049; 180-day: P = 0.004) showed higher risk of readmission, while patients with only obesity phenotypes MHO (90-day: P = 0.170; 180-day: P = 0.090) experienced no higher risk. However, similar associations were not observed for 30-day and 60-day. Further analysis in 90-day follow-up revealed that, readmission risk elevated with the increase of the combined factor numbers, with aHR of 1.068 (CI: 1.002-1.137, P = 0.043, with one metabolic risk factor), 1.109 (CI: 1.038-1.184, P = 0.002, with two metabolic risk factors) and 1.125 (95% CI: 1.04-1.216, P = 0.003, with three metabolic risk factors), respectively.ConclusionMetabolic disorders, rather than obesity, were independently associated with higher readmission risk in patients with MM, whereas the risk elevated with the increase of the number of combined metabolic factors. However, the effect of metabolic disorders on MM readmission seems to be time-dependent. For MM patient combined with metabolic disorders, more attention should be paid to advance directives to reduce readmission rate and hospitalization burden.

Elevation of energy expenditure through an increase of brown adipose tissue (BAT) thermogenesis is regarded as one of the most promising ways to prevent obesity development. The preoptic area (POA) of the hypothalamus is a critical area for control of BAT thermogenesis. However, the intracellular signaling cascades in the POA for regulation of BAT thermogenesis are poorly understood.Phosphorylation proteomics (phosphoproteomics) and bioinformatics approaches were used to disclose numerous hypothalamic signaling pathways involved in the regulation of BAT thermogenesis. Conditional manipulation of the p38α gene in mouse POA was performed by stereotaxic injection of adeno-associated virus 9 vector to explore the role of p38α in BAT thermogenesis.Multiple hypothalamic signaling pathways were triggered by cold exposure, especially the mitogen-activated protein kinase (MAPK) signaling pathway. The p38α activation, but not extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun NH2-terminal kinase (JNK), in the hypothalamus was significantly decreased during cold exposure. p38α deficiency in the POA dramatically elevated energy expenditure owing to a marked increase in BAT thermogenesis, resulting in significantly decreased body weight gain and fat mass. Overexpression of p38α in the POA led to a dramatic increase in weight gain.These results demonstrate that p38α in the POA exacerbates obesity development, at least in part owing to a decrease in BAT thermogenesis.

ObjectiveMost evidence comes from studies show that ambient ozone(O3) pollution has become a big issue in China. Few studies have investigated the impact of ozone spatiotemporal patterns on respiratory mortality and cardiovascular mortality in Nanchang city. Thus, this study aimed to explore the health effect of ozone exposure on respiratory mortality and cardiovascular mortality in Nanchang, Jiangxi Province.MethodsUsing the daily mortality data, atmospheric routine monitoring data and meteorological data in Nanchang from 2014 to 2020, we performed a generalized additive model (GAM) based on the poisson distribution in which time-series analysis to calculate the risk correlation between respiratory mortality and cardiovascular mortality and ozone exposure level (8h average ozone concentration, O3-8h). Besides, analyses were also stratified by season, age and sex.ResultsIn the single-pollutant model, for every 10 μg/m3 increase in ozone, respiratory mortality increased 1.04% with 95% confidence interval (CI) between 0.04 and 1.68%, and cardiovascular mortality increased 1.26% (95%CI: 0.68 ~ 1.83%). In the multi-day moving average lag model, the mortality of respiratory diseases and cardiovascular diseases reached a relative risk peak on the cumulative lag5 (1.77%,95%CI: 0.99 ~ 2.57%) and the cumulative lag3 (1.68%,95%CI: 0.93 ~ 2.45%), respectively. The differences were statistically significant (P < 0.05). Results of the stratified analyses showed the effect value of respiratory mortality in people aged ≥65 years was higher than aged P < 0.05).ConclusionsIn the long run, the more extreme the pollution of ozone exposure, the higher the health risk of residents' respiratory mortality and cardiovascular mortality. Therefore, the government should play an important role in the prevention and control ways of decreasing and eliminating the ozone pollution to protect the resident's health. The findings provide valuable data for further scientific research and improving environmental policies in Nanchang city.

In this paper, a vision-based guiding method was proposed to address the issue of autonomous route planning for micro Quadrotor Unmanned Aerial Vehicle (quad-UAV). In the autonomous flight stage, the skeleton line, which represents the main extension of roads, is extracted to get the potential forward direction (FD). Then the current FD is defined as the minimum value of all angles between potential FD with the last FD. In the stage of autonomous landing, the parking apron is detected based on the roundness of a closed region with an appropriate threshold. To tradeoff the stability and speed, the forward destination location is calculated according to the amplitude of change of the FD. Additionally, the PID controller is further applied in the whole route planning. The proposed algorithm is verified on the parrot micro quad-UAV platform. And the results illustrate that the proposed scheme can autonomously control the UAV fly along the road and land on the parking apron, and exhibit good performance.

We investigated the effect of polyphenols extracted from M. angusticepes Peck (PMP) on D-galactosamine/lipopolysaccharide (D-GalN/LPS) induced acute hepatic failure (AHF) in mice. Results indicated that administration of PMP relieved the leakage of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The level of serum ALT was reduced in groups of P-H (800 mg PMP/kg BW) and P-L (400 mg PMP/kg BW) by 44.6% and 31.8%, respectively. RT-PCR and Western blot analyses showed that NF-E2-related factor 2 (Nrf2), PPARα, PPARγ gene and protein were up-regulated after injection D-GalN/LPS. In contrast, PMP pretreatment noticeably prevented D-GalN/LPS-induced hepatocyte apoptosis and steatosis. It suggested that PMP attenuated D-GalN/LPS-induced AHF in mice, which was likely attributed to the co-activation of Nrf2, PPARα, PPARγ and alleviating the oxidative stress reaction, reducing the body inflammatory response and regulating the lipid metabolism.

Background Patients with estrogen receptor negative (ER−) breast cancer have poor prognosis due to high rates of metastasis. However, there is no effective treatment and drugs for ER− breast cancer metastasis. Our purpose of this study was to evaluate the effect of lotus leaf alcohol extract (LAE) on the cell migration and metastasis of ER− breast cancer. Methods The anti-migratory effect of LAE were analyzed in ER− breast cancer cells including SK-BR-3, MDA-MB-231 and HCC1806 cell lines. Cell viability assay, wound-healing assay, RNA-sequence analysis and immunoblotting assay were used to evaluate the cytotoxicity and anti-migratory effect of LAE. To further investigate the inhibitory effect of LAE on metastasis in vivo, subcutaneous xenograft and intravenous injection nude mice models were established. Lung and liver tissues were analyzed by the hematoxylin and eosin staining and immunoblotting assay. Results We found that lotus LAE, not nuciferine, inhibited cell migration significantly in SK-BR-3, MDA-MB-231 and HCC1806 breast cancer cells, and did not affect viability of breast cancer cells. The anti-migratory effect of LAE was dependent on TGF-β1 signaling, while independent of Wnt signaling and autophagy influx. Intracellular H2O2 was involved in the TGF-β1-related inhibition of cell migration. LAE inhibited significantly the breast cancer cells metastasis in mice models. RNA-sequence analysis showed that extracellular matrix signaling pathways are associated with LAE-suppressed cell migration. Conclusions Our findings demonstrated that lotus leaf alcohol extract inhibits the cell migration and metastasis of ER− breast cancer, at least in part, via TGF-β1/Erk1/2 and TGF-β1/SMAD3 signaling pathways, which provides a potential therapeutic strategy for ER− breast cancer.

Additional file 1: Fig. S1. Wnt and autophagy signaling pathways. Fig. S2. Gene expression profiles of cells with LAE supplement by RNA-sequence. Fig. S3. Nuciferine effect on the inhibition of cell migration by LAE.

Background: Patients with estrogen receptor negative (ER-) breast cancer have poor prognosis because of their high rates of metastasis. However, there is no effective treatment and drugs for ER− breast cancer metastasis. Our purpose of this study was to evaluate the effect and mechanism of lotus leaf alcohol extract (LAE) on the cell migration and metastasis of ER- breast cancer.Methods: The anti-migratory effect and mechanism of LAE were analysed in ER- breast cancer cells including SK-BR-3, MDA-MB-231 and HCC1806. Cell viability assay, wound-healing assay, RNA-sequence analysis and immunoblotting assay were applied in examining the cytotoxicity, anti-migratory effect and its possible pathways of LAE. To further investigate the inhibitory effect of LAE on metastasis in vivo, subcutaneous xenograft nude mice model and intravenous injection nude mice model were established. Lung and liver tissues were analysed by the Hematoxylin & eosin staining and immunoblotting assay.Results: We found that lotus leaf alcohol extract (LAE), not nuciferine, inhibited cell migration significantly in SK-BR-3, MDA-MB-231 and HCC1806 breast cancer cells, and did not change viability of breast cancer cells. The anti-migratory effect of LAE was dependent on TGF-β1 signaling, while independent of Wnt signaling and autophagy influx. Intracellular H2O2 participated in the TGF-β1-related inhibition of cell migration. LAE inhibited significantly the breast cancer cells metastasis in mice models. RNA-sequence analysis showed that extracellular matrix signaling pathways are associated with LAE-suppressed cell migration.Conclusions: Our findings demonstrated that lotus leaf alcohol extract inhibits the cell migration and metastasis of ER- breast cancer via TGF-β1/Erk1/2 and TGF-β1/SMAD3 signaling, which provides a potential therapeutic strategy for ER- breast cancer.

Background Patients with estrogen receptor negative (ER−) breast cancer have poor prognosis due to high rates of metastasis. However, there is no effective treatment and drugs for ER− breast cancer metastasis. Our purpose of this study was to evaluate the effect of lotus leaf alcohol extract (LAE) on the cell migration and metastasis of ER− breast cancer. Methods The anti-migratory effect of LAE were analyzed in ER− breast cancer cells including SK-BR-3, MDA-MB-231 and HCC1806 cell lines. Cell viability assay, wound-healing assay, RNA-sequence analysis and immunoblotting assay were used to evaluate the cytotoxicity and anti-migratory effect of LAE. To further investigate the inhibitory effect of LAE on metastasis in vivo, subcutaneous xenograft and intravenous injection nude mice models were established. Lung and liver tissues were analyzed by the hematoxylin and eosin staining and immunoblotting assay. Results We found that lotus LAE, not nuciferine, inhibited cell migration significantly in SK-BR-3, MDA-MB-231 and HCC1806 breast cancer cells, and did not affect viability of breast cancer cells. The anti-migratory effect of LAE was dependent on TGF-β1 signaling, while independent of Wnt signaling and autophagy influx. Intracellular H2O2 was involved in the TGF-β1-related inhibition of cell migration. LAE inhibited significantly the breast cancer cells metastasis in mice models. RNA-sequence analysis showed that extracellular matrix signaling pathways are associated with LAE-suppressed cell migration. Conclusions Our findings demonstrated that lotus leaf alcohol extract inhibits the cell migration and metastasis of ER− breast cancer, at least in part, via TGF-β1/Erk1/2 and TGF-β1/SMAD3 signaling pathways, which provides a potential therapeutic strategy for ER− breast cancer.

This study analyzed the cellular antioxidant and antiproliferative activities, as well as the phenolic composition of three Morchella conica Pers. cultures. Results showed that the free phenolic contents of the three Morchella conica Pers. ranged from 4.928 to 6.157 mg GAE/g DW and their bound phenolic contents ranged from 0.188 to 0.250 mg GAE/g DW. Polyphenols in M. conica Pers. were dominated by phenolic acids, particularly for gallic acid. The free phenolic extracts exhibited higher cellular antioxidant activity than the bound phenolic extracts. Free phenolics in M. conica Pers. cultured from Yunnan China showed the highest antiproliferative activity against HepG2 cells, whereas bound phenolics in M. conica cultured from Tibet China showed the highest antiproliferative activity. Results confirmed that Morchella conica Pers. (growing in Yunnan China especially) could be a new source of natural antioxidant and a potential inhibitor for the growth of HepG2 cells.

Phenolics extracted from tartary buckwheat (Fagopyrum tartaricum L. Gaerth) bran were analyzed quantitatively and qualitatively. The bioactivity of the phenolic extracts was evaluated, such as the antioxidant activity, and the inhibition capacity on the growth of cancer cells. The molecular mechanism for the inhibitive effect on cancer cells was explored. Results indicated that tartary buckwheat bran phenolics mainly exist in a free form, and free phenolics were twice as abundant as bound phenolics. Free caffeic acid (119.75 μg per 100 mg DW) and bound rutin (51.66 μg per 100 mg DW) represented the main free and bound phenolic compounds, respectively. The free phenolic extract contributed to the major (>90%) antioxidant activities including the oxygen radical antioxidant capacity (ORAC) and cellular antioxidant activity (CAA). The free phenolic extract exhibited anticancer activity for human breast cancer MDA-MB-231 cells in a dose-dependent manner. This significant inhibition effect was achieved through the p38/MAP kinase pathway by inducing cell apoptosis (up-regulating p-p38 and p-ASK1 expressions and down-regulating TRAF2 and p-p53 expressions), and negatively regulating the progression of the cell cycle from the G1 to S phase (increased expression of p21 and suppressed expressions of PCNA, cyclin D1 and CDK4). All these results indicated that tartary buckwheat bran could be a rich resource of natural antioxidants and inhibitors for the growth of MDA-MB-231 cells.

Tartary buckwheat bran [ Fagopyrum tartaricum (L.) Gaerth, FG], a major by-product of tartary buckwheat flour production, may serve as a natural source of phenolic compounds with potential antioxidant activity. In this study, the total content of free phenolic compounds was approximately 4-fold larger than that of bound phenolic compounds. Rutin represented the main phenolic compound existing in both free and bound forms. However, caffeic acid hexose, chlorogenic acid, protocatechuic acid and catechin-glucoside were only detected in the bound phenolic fraction. The biological activity tests indicated that the phenolic extracts (free fraction especially) of tartary buckwheat bran might serve as functional compounds that exert antioxidant activities in vitro (oxygen radical antioxidant capacity, ORAC) and ex-vivo (cellular antioxidant activities, CAA), as well as antiproliferative activity against human liver cancer cells (HepG2) in vitro .

Thrust Management System is an important part of Flight Management System in larger aircraft. Thrust management technology is used effectively can improve the economics of the aircraft. This paper introduces the system structure and function principle of Thrust System Management technology, including different thrust management ways, as well as working under different flight conditions. A new limit thrust management method to get the maximum allowable EPR is put forward, and thrust control system and auto-throttle system are analyzed and simulated. The simulation results show that the auto-throttle can achieve flight speed mode of Thrust Management System.

Unmanned aerial vehicle (UAV) has been widely used in military and civil fields due to its unique advantages. Aiming at the principle of UAV in reconnaissance field and target recognition field, a method of UAV multi-target recognition based on image processing is proposed, and the validity of the method is verified by building an UAV platform and field experiments. At the same time, the display interface of image processing results is developed, which can get the UAV recognition results in real time. Finally, the experimental results are analyzed, and the factors affecting the accuracy of UAV target recognition are elaborated.

This study investigated histopathologic changes in dental pulp after treatment with low-intensity pulsed ultrasound (LIPUS). Fifty rats were randomly divided into an experimental group (n = 25) and a blank control group (n = 25). In the experimental group, a cavity was prepared in the bilateral maxillary first molars. The upper right first molars were stimulated with LIPUS (30 mW/cm2, 1.5 MHz) for 20 min/d. The cavities prepared in the left teeth were used as experimental controls (i.e., no LIPUS). Five rats in each group were sacrificed at days 1, 3, 5, 7 and 14. Inflammatory response was visible at different time points after cavity preparation, peaking at day 3, after which it gradually weakened. More reparative dentin was found on the LIPUS treatment side. transforming growth factor-β1 expression increased after treatment, peaking at day 5 and returning to normal at day 14 on both sides, but was stronger with LIPUS treatment. SMAD2 and SMAD3 expressions in the dental pulp gradually increased after cavity preparation, especially in the experimental group. LIPUS promoted the repair of dentin–pulp complex injury, to a certain extent and should be investigated further as a potential therapy.

This paper focuses on multiplayer cooperative interaction in a shared haptic environment based on a local area network. Decoupled motion control, which allows one user to manipulate a haptic interface to control only one-dimensional movement of an avatar, is presented as a new type haptic-based cooperation among multiple users. Users respectively move an avatar along one coordinate axis so that the motion of the avatar is the synthesis of movements along all axes. It is different from previous haptic cooperation where all users can apply forces on an avatar along any direction to move it, the motion of which completely depends on the resultant force. A novel concept of movement feedback is put forward where one user can sense other users’ hand motions through his or her own haptic interface. The concept can also be explained wherein one person who is required to move a virtual object along only one axis can also feel the motions of the virtual object along other axes. Movement feedback, which is a feeling of motion, differs from force feedback, such as gravity, collision force and resistance. A spring-damper force model is proposed for the computation of motion feedback to implement movement transmission among users through haptic devices. Experimental results validate that movement feedback is beneficial for performance enhancement of such kind of haptic-based cooperation, and the effect of movement feedback in performance improvement is also evaluated by all subjects.Copyright © 2012 John Wiley & Sons, Ltd.

Haptic-based paradigms for human motor skill training which include virtual fixture, record-play method, shared control scheme and haptic disturbance have been proposed and widely used for applications like surgery, assembly, rehabilitation, motor skill and so on. However, no haptic-based training scheme applies to all types of human motor skills that new ideas and new approaches should be explored for some special training tasks. For example, tank gunners have to be rigorously trained to be able to complete the most accurate manipulation in the shortest possible time. Accuracy and operating speed are both critical for them to grasp the skill; therefore, tank gunnery is defined as a type of high precision and high speed human motor skill. In this paper, a hybrid spring-damper model which fuses haptic fixture and record-play is presented to simultaneously train accuracy and operating speed. The training approach is suitable for novices at all levels since force feedback is decomposed into two components: one for training accuracy, the other for training speed. The virtual envelope depicting is chosen as the training task for novices to validate the effectiveness of the proposed haptic-based scheme in high precision and high speed skill training. Experimental results indicate that force feedback generated based on the hybrid model can benefit novices in fast improving performances on tank gunnery.

For training human motor skills, haptic guidance has proven more effective than traditional visual-feedback-only approaches. However, novices might become dependent on the feedback force provided during training and become unable to adapt to real operating environments. To overcome haptic-based training's limitations, a proposed approach uses decoupled motion control, which divides a motion into individual coordinate axis movements controlled by multiple operators. Using a networked haptic interaction system, the trainee cooperates with an expert to complete a training task. Unlike previous approaches, the force or torque exerted by the trainee's device doesn't directly correct the trainee's hand action. Instead, the trainee regulates his or her manipulation to cooperate with the expert by feeling motion feedback from the expert. The Web extra at http://youtu.be/qYBsR6AOjzQ is a video that shows a test subject operating a training simulator for tank gunnery that uses haptics.

A study on collaborative game in shared virtual environment with haptic feedback over computer networks is introduced in this paper. A collaborative task was used where the players located at remote sites and played the game together. The player can feel visual and haptic feedback in virtual environment compared to traditional networked multiplayer games. The experiment was desired in two conditions: visual feedback only and visual-haptic feedback. The goal of the experiment is to assess the impact of force feedback on collaborative task performance. Results indicate that haptic feedback is beneficial for performance enhancement for collaborative game in shared virtual environment. The outcomes of this research can have a powerful impact on the networked computer games.

Zheng-yan Yang,1,2 Fei Wang,1,2 Keke Lu,1,2 Yue-heng Li,1,2 Zhi Zhou1,2 1Department of Preventive Dentistry, The College of Stomatology, 2Department of Preventive Dentistry, The Affiliated Hospital of Stomatology, Chongqing Medical University, Chongqing, People's Republic of China Objective: To estimate the effect of arginine-containing desensitizing toothpaste on dentin hypersensitivity (DH). Methods: Databases including China National Knowledge Infrastructure, VIP Database for Chinese Technical Periodicals, China Biology Medicine disc, Wangfang Data, PubMed, Web of Science, and Cochrane Trials Register were searched, and Google was used as a supplementary tool to search for information through February 2014. Randomized controlled trials (RCTs) of the treatment of DH with arginine-containing toothpaste were included. Relevant information was extracted, and a quality evaluation was performed. Meta-analyses were performed using RevMan 5.2 software. Results: Eighteen RCTs with 1,423 patients were included. The results of the meta-analyses demonstrated that at days 0 and 3; weeks 2, 4, and 8; and more than 12 weeks, arginine-containing toothpaste led to significantly improved results on the tactile sensitivity test (standardized mean difference [SMD] =1.95, 95% confidence interval [CI] [1.14, 2.76]) and the air-blast test (SMD =-1.60, 95% CI [-2.14, -1.05]) at 4 weeks and the tactile sensitivity test (SMD =2.01, 95% CI [1.41, 2.61]) and the air-blast test (SMD =-1.41, 95% CI [-1.83, -0.98]) at 8 weeks compared to toothpastes containing other desensitizing components, thus indicating a superior therapeutic effect of arginine-containing desensitizing toothpaste. However, no significant differences between arginine-containing toothpaste and toothpastes containing other desensitizing components were observed in the air-blast test at days 0 and 3 and week 2 and in the tactile sensitivity and air-blast tests at more than 12 weeks. Conclusion: The current evidence indicates that arginine-containing toothpaste is effective for DH. However, further high-quality, large-sample RCTs are needed. Keywords: arginine-containing toothpastes, dentin hypersensitivity, meta-analysis, randomized controlled trial&nbsp

When building an Integrated circuit (IC) manufacturing system simulation model, the practices normally simplify some complex features to ensure build ability and run ability. However, this brings the consequence of model imprecision; parameters disable to represent actual situation, etc. This paper proposes parameter optimizing approaches in IC manufacturing system simulation model based on the offline weighted average method and Kolmogorov–Smirnov (K–S) test method. They are on the basis of the processing time’s feature, for the parameter reflects the overall character of the sample’s former performance and at the same time, the system has a great amount of historical data. The approaches are to optimize the whole model by optimizing the significant processing time parameter. It turns out that both the weighted average method and the K–S test based method can improve the precision of model.

This paper introduces networked tank gunnery skill training based on haptic interaction. “Hand in hand” training mode is implemented by constructing a networked haptic display system. A teacher and a trainee can respectively manipulate his own haptic device to realize skill transferring. In this process, the trainee can experience the teacher's motor skill and can be corrected by the teacher. A local network is built to connect two haptic devices and computers. Two modes for tank gunnery skill training are designed in this system: haptic guidance and realtime correction. A prototype system is established to testify the effectiveness of such a new type “Hand in hand” training system.

In this paper we study on haptic collaboration in a maze game over computer network. Two players located at separated places operate each haptic device to collaboratively finish the game task. Herein, a new collaboration mode of manipulation - separate DOF control is proposed for the first time. Separate DOF control here means each player controls one DOF of an object or a task independently in collaborative virtual environment. Mutual guidance is also proposed which provides guidance force to each player. We setup an experiment to evaluate its efforts on cooperation performance and co-presence. Twelve participants did the experiment. The results revealed that this collaboration mode is effective. Ten of the twelve participants believed that they performed well in the experiment and thought the collaboration way was very interesting. The presented results motivated a new haptic collaboration mode in the fields of game design, education and cooperative assembly.

A study on tank gunnery motor skill training is introduced in this paper. We developed a two-mode system used for teaching and training. In the haptic guidance mode, the trainee is passive and experiences position playback of the expert's motion with a proportional-derivation (PD) controller. In the path constraining mode, the trainee operates the haptic device actively, and the aiming point in the virtual environment is constrained on the desired path. A new haptic rendering algorithm is introduced in this mode. An experiment for record-play motion of drawing a virtual sine path and path constraining with drawing an envelope path is designed. Results indicate that the haptic rendering algorithm in the two-mode training system is stable.