An Empirical Study Of Flow Experiences In Social Network Sites

Social network sites (SNS) have simplified and amplified social interaction between online users. The unique hedonic-oriented features provide experiential motives for SNS users. Although SNS is growing popularity, a number of questions remain to be addressed concerning the usage of SNS: What are experiential motives for SNS users? What is the relationship between flow experiences and behavioural intentions within the SNS context? Given the novelty of SNS phenomenon and its unexplored potential in many fields, this study develops a conceptual model derived from reference studies on online services and social psychology. The present study proposes four flow experiences of SNS users such as perceived enjoyment, concentration, escape and social interaction to represent the multidimensional aspect of flow instead of a single dimension. To investigate the research model, this study apply structural equation mode(SEM) analysis with 342 valid replies. As a result, this empirical study indicated that perceived enjoyment was the most important flow experience with SNS, followed by escape and social interaction. Concentration was not a significant predictor of behavioral intentions toward SNS

Understanding Repeat Purchase Intentions And Uncertainty In The Context Of Online Shopping

The distant and impersonal nature of e-commerce (EC) and the unpredictability of the Internet infrastructure generate an implicit uncertainty around online transactions. Moreover, customer repeat purchasing is critical to the e-commerce vendor’s survival and success. However, few studies explain online repeat purchase from an uncertainty perspective. The purpose of this study is to propose a conceptual model to examine the sources of uncertainty and types of uncertainty in an online transaction, which affect online repeat purchase intentions. We drew on uncertainty and online repeat purchase literature to formulate a conceptual model that identifies the sources of uncertainty, and three types of uncertainty (seller uncertainty, product uncertainty and environmental uncertainty) are respectively proposed as formative second-order constructs. The proposed structural model is empirically tested with data from 554 experienced online shoppers, and then analyzed using Structure Equation Model (SEM). The results show that seller uncertainty and environmental uncertainty have a negative effect on repeat purchase intentions. Implications for theory and practice and suggestions for future research are discussed

BIOMECHANICAL EFFECT OF GROUP EXERCISE PROGRAM USING STABILITY BALL ON THE COUNTER MOVEMENT JUMP

The purpose of this study was to evaluate the training effect of three-month group exercise program using stability ball. Ten female subjects were recruited to join this group exercise class for three months. The biomechanical parameters of counter-movement jump were collected before and after class. The average of maximal jumping height and the take-off velocity have significantly increased after three months. The group exercise program accoring American College of Sport Medicine trainig guideline which was designed in this study was helpful to increase the jump height of counter movement jump and to improve the biomechanical parameters of the landing

Report on Provider-Client Interaction From 68 Methadone Maintenance Clinics in China.

Provider-client interaction is an integral of clinical practice and central to the delivery of high-quality medical care. This article examines factors related to the provider-client interaction in the context of methadone maintenance treatment (MMT). Data were collected from 68 MMT clinics in China. In total, 418 service providers participated in the survey. Linear mixed effects regression models were performed to identify factors associated with provider-client interaction. It was observed that negative attitude toward drug users was associated with lower level of provider-client interaction and less time spent with each client. Other factors associated with lower level of interaction included being female, being younger, being a nurse, and fewer years in medical field. Higher provider-client interaction was associated with provider reported job satisfaction. The findings of this study call for a need to address provider negative attitudes that can impact provider-client interaction and the effectiveness of MMT. Future intervention efforts targeting MMT providers should be tailored by gender, provider type, and medical experiences

Antioxidant Properties of Polysaccharide from the Brown Seaweed Sargassum graminifolium (Turn.), and Its Effects on Calcium Oxalate Crystallization

We investigated the effects of polysaccharides from the brown seaweed Sargassum graminifolium (Turn.) (SGP) on calcium oxalate crystallization, and determined its antioxidant activities. To examine the effects of SGP on calcium oxalate crystallization, we monitored nucleation and aggregation of calcium oxalate monohydrate crystals, using trisodium citrate as a positive control. We assessed antioxidant activities of SGP by determining its reducing power, its ability to scavenge superoxide radicals, and its activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The nucleation inhibition ratio of trisodium citrate and SGP was 58.5 and 69.2%, respectively, and crystal aggregation was inhibited by 71.4 and 76.8%, respectively. Increasing concentrations of SGP resulted in increased scavenging of superoxide anions and DPPH radicals (IC50 = 1.9 and 0.6 mg/mL, respectively). These results suggest that SGP could be a candidate for treating urinary stones because of its ability to inhibit calcium oxalate crystallization and its antioxidant properties

Estimation of cotton canopy parameters based on unmanned aerial vehicle (UAV) oblique photography

Background: The technology of cotton defoliation is essential for mechanical cotton harvesting. Agricultural unmanned aerial vehicle (UAV) spraying has the advantages of low cost, high efficiency and no mechanical damage to cotton and has been favored and widely used by cotton planters in China. However, there are also some problems of low cotton defoliation rates and high impurity rates caused by unclear spraying amounts of cotton defoliants. The chemical rate recommendation and application should be based upon crop canopy volume rather than on land area. Plant height and leaf area index (LAI) is directly connected to plant canopy structure. Accurate dynamic monitoring of plant height and LAI provides important information for evaluating cotton growth and production. The traditional method to obtain plant height and LAI was s a time-consuming and labor-intensive task. It is very difficult and unrealistic to use the traditional measurement method to make the temporal and spatial variation map of plant height and LAI of large cotton fields. With the application of UAV in agriculture, remote sensing by UAV is currently regarded as an effective technology for monitoring and estimating plant height and LAI. Results: In this paper, we used UAV RGB photos to build dense point clouds to estimate cotton plant height and LAI following cotton defoliant spraying. The results indicate that the proposed method was able to dynamically monitor the changes in the LAI of cotton at different times. At 3 days after defoliant spraying, the correlation between the plant height estimated based on the constructed dense point cloud and the measured plant height was strong, with R2 and RMSE values of 0.962 and 0.913, respectively. At 10 days after defoliant spraying, the correlation became weaker over time, with R2 and RMSE values of 0.018 and 0.027, respectively. Comparing the actual manually measured LAI with the estimated LAI based on the dense point cloud, the R2 and RMSE were 0.872 and 0.814 and 0.132 and 0.173 at 3 and 10 days after defoliant spraying, respectively. Conclusions: Dense point cloud construction based on UAV remote sensing is a potential alternative to plant height and LAI estimation. The accuracy of LAI estimation can be improved by considering both plant height and planting density

Timeframe for return to driving for patients with minimally invasive knee arthroplasty is associated with knee performance on functional tests

BACKGROUND: This study hopes to establish the timeframe for a safe return to driving under different speed conditions for patients after minimally invasive total knee arthroplasty and further explores how well various kinds of functional tests on knee performance can predict the patients’ braking ability. METHODS: 14 patients with right knee osteoarthritis were included in the present study and instructed to perform three simulated driving tasks at preoperative, 2 weeks postoperative and 4 weeks postoperative. RESULTS: The results showed that the total braking time at 4 week postoperative has attained the preoperative level at the driving speed 50 and 70 km/hr but not at the driving speed 90 km/hr. It had significantly improving in knee reaction time and maximum isometric force at 4 weeks postoperative. Besides, there was a moderate to high correlation between the scores of the step counts and the total braking time. CONCLUSIONS: Summary, it is recommended that driving may be resumed 4 weeks after a right knee replacement but had to drive at low or moderate speed and the best predictor of safety driving is step counts

THE EFFECT OF MACH DRILLS TRAINING ON THE START MOVEMENT OF IN-LINE SPEED SKATING

The purpose of this study was to analyze the relative muscle activation of the start movement and the Mach Drills training program. 5 in-line skating players participated in the study and 9 Wireless EMG sensors were placed over the rectus femoris, biceps femoris, semitendinosus, tibialis anterior, gastrocnemius, peroneus longus, adductor magnus, tensor fascia lata, and gluteus maximus. Results showed that significantly lower gastrocnemius IEMG value in skating. However, it also showed that RF, TA, and PL had higher IEMG value in skating and significant difference was found for TA. Another muscle activation didn’t have significantly difference. It suggested that athletes had to increase more specific training program for rectus femoris muscle and peroneus longus muscle which play an important roles for start movement in skating

3β-Acet­oxy-8β,10β-dihy­droxy-6β-meth­oxy­eremophil-7(11)-en-8,12-olide

The title compound, C18H26O7, is an eremophilenolide which has been isolated from the plant Ligularia duciformis for the first time. The present study confirms the atomic connectivity assigned on the basis of 1H and 13C NMR spectroscopy. The mol­ecule contains three fused rings, two six-membered rings in chair confomations and a five-membered ring in a flattened envelope conformation. Two hy­droxy groups are involved in formation of intra- and inter­molecular O—H⋯O hydrogen bonds. The latter ones link mol­ecules into chains propagating in [010]

Parallel Acceleration and Improvement of Gravitational Field Optimization Algorithm

The Gravitational Field Algorithm, a modern optimization algorithm, mainly simulates celestial mechanics and is derived from the Solar Nebular Disk Model (SNDM). It simulates the process of planetary formation to search for the optimal solution. Although this optimization algorithm has more advantages than other optimization algorithms in multi-peak optimization problems, it still has the shortcoming of long computation time when dealing with large-scale datasets or solving complex problems. Therefore, it is necessary to improve the efficiency of the Gravitational Field Algorithm (GFA). In this paper, an optimization method based on multi-population parallel is proposed to accelerate the Gravitational Field Algorithm. With the help of the parallel mechanism in MATLAB, the algorithm execution speed will be improved by using the parallel computing mode of multi-core CPU. In addition, this paper also improves the absorption operation strategy. By comparing the experimental results of eight classical unconstrained optimization problems, it is shown that the computational efficiency of this method is improved compared with the original Gravitational Field Algorithm, and the algorithm accuracy has also been slightly improved