bluuebunny/crossref_metadata_2025_split huggingface dataset:
Validation of a Novel Virtual Reality Training Curriculum for Robotic Cardiac Surgery a Randomized Trial
Authors: Valdis Matthew , Chu Michael W. A. , Schlachta Christopher M. , Kiaii Bob 
Published: December 2015

Objective Robotic cardiac surgery training has relied entirely on classical methods of surgical teaching. We sought to evaluate the impact of a virtual reality (VR) simulation curriculum to improve skill acquisition in robotic cardiac surgery. Methods We randomly assigned 20 surgical trainees to undergo a 9-exercise VR curriculum on a robotic surgical simulator or a control group that received no additional training. The trainees were then evaluated in a blinded fashion by assessing their de-identified video recordings of the following: (1) standardized robotic internal thoracic artery harvest and (2) mitral valve annuloplasty performed in porcine models, using a validated time-based scoring system and an objective intraoperative scoring tool. Postintervention assessments were compared to baseline. Results Trainees randomized to the VR group were faster than the control group for both the internal thoracic artery harvest (957.3 ± 98.9 vs. 749.1 ± 171.9; P = 0.004) and mitral annuloplasty (580.4 ± 14.4 vs. 463.8 ± 86.4; P < 0.001) and scored significantly higher with the intraoperative scoring tool (22.8 ± 2.7 vs. 11.0 ± 4.5; P < 0.001). Additionally, the VR group achieved a proficiency level similar to our experts for both time-based scores (P = 0.624 and P = 0.967), and the intraoperative assessment (P = 0.110), whereas the control group was not able to meet this level of proficiency for any of the primary outcomes. The average duration of training to successfully complete all required tasks was 9.3 hours. Conclusions We have demonstrated that a VR simulation curriculum can significantly improve the efficiency and quality of learning in robotic cardiac surgery. Further evaluation of this curriculum is required for its widespread implementation in surgical training (ClinicalTrials.gov, NCT#02357056).
Multi-objective enhanced PSO algorithm for optimizing power losses and voltage deviation in power systems
Authors: Chen Gonggui , Liu Lilan , Guo Yanyan , Huang Shanwai 
Published: December 2015

Purpose
– For one thing, despite the fact that it is popular to research the minimization of the power losses in power systems, the optimization of single objective seems insufficient to fully improve the performance of power systems. Multi-objective VAR Dispatch (MVARD) generally minimizes two objectives simultaneously: power losses and voltage deviation. The purpose of this paper is to propose Multi-Objective Enhanced PSO (MOEPSO) algorithm that achieves a good performance when applied to solve MVARD problem. Thus, the new algorithm is worthwhile to be known by the public.

Design/methodology/approach
– Motivated by differential evolution algorithm, cross-over operator is introduced to increase particle diversity and reinforce global searching capacity in conventional PSO. In addition to that, a constraint-handling approach considering Constrain-prior Pareto-Dominance (CPD) is presented to handle the inequality constraints on dependent variables. Constrain-prior Nondominated Sorting (CNS) and crowding distance methods are considered to maintain well-distributed Pareto optimal solutions. The method combining CPD approach, CNS technique, and cross-over operator is called the MOEPSO method.

Findings
– The IEEE 30 node and IEEE 57 node on power systems have been used to examine and test the presented method. The simulation results show the MOEPSO method can achieve lower power losses, smaller voltage deviation, and better-distributed Pareto optimal solutions comparing with the Multi-Objective PSO approach.

Originality/value
– The most original parts include: the presented MOEPSO algorithm, the CPD approach that is used to handle constraints on dependent variables, and the CNS method which is considered to maintain a well-distributed Pareto optimal solutions. The performance of the proposed algorithm successfully reflects the value of this paper.
A comprehensive sensorless control of DFIG-based wind turbines
Authors: Abedinzadeh Taher , Tohidi Sajjad 
Published: December 2015

Purpose– The purpose of this paper is to present an improved approach for estimation of the rotor position and speed of doubly fed induction generator, which can be used in vector control and direct torque control (DTC) schemes.Design/methodology/approach– Some novel equations are developed for calculation of the rotor position and rotor speed. Such equations do not need to the value of stator flux linkage and just, measured values of the stator voltage and currents as well as rotor current are required to be known.Findings– The simulation results verify the satisfactory steady-state and dynamic performance of proposed approach with both the vector control and DTC schemes. The results show that the proposed estimation approach benefits from the starting on the fly, robustness against the variations of the most of the stator and rotor parameters and immunity against the noise.Originality/value– The proposed estimation approach is novel and the outcome of the research of authors. It is simple and effective and, no approximation is made in the calculations. The simulation results demonstrate that the proposed scheme can be successfully implemented in various control strategies, e.g. DTC and vector control.
Upward and downward conjugate mixed convection heat transfer in a partially porous cavity
Authors: Bourouis Abderrahim , Omara Abdeslam , Abboudi Said 
Published: December 2015

Purpose
– The purpose of this paper is to provide a numerical study of conjugate heat transfer by mixed convection and conduction in a lid-driven enclosure with thick vertical porous layer. The effect of the relevant parameters: Richardson number (Ri=0.1, 1, 10) and thermal conductivity ratio (Rk=0.1, 1, 10, 100) are investigated.

Design/methodology/approach
– The studied system is a two dimensional lid-driven enclosure with thick vertical porous layer. The left vertical wall of the enclosure is allowed to move in its own plane at a constant velocity. The enclosure is heated from the right vertical wall isothermally. The left and the right vertical walls are isothermal but temperature of the outside of the right vertical wall is higher than that of the left vertical wall. Horizontal walls are insulated. The governing equations are solved by finite volume method and the SIMPLE algorithm.

Findings
– From the finding results, it is observed that: for the two studied cases, heat transfer rate along the hot wall is a decreasing function of thermal conductivity ratio irrespective of Richardson numbers contrary to the heat transfer rate along the fluid-porous layer interface which is an increasing function of thermal conductivity ratio. At forced convection dominant regime, the difference between heat transfer rate for upward and downward moving wall is insensitive to the thermal conductivity ratio. For downward moving wall, average Nusselt number is higher than that of upward moving wall.

Practical implications
– Some applications: building applications, furnace design, nuclear reactors, air solar collectors.

Originality/value
– From the bibliographic work and the authors’ knowledge, the conjugate mixed convection in lid-driven partially porous enclosures has not yet been investigated which motivates the present work that represent a continuation of the preceding investigations.
Influence of incidence angle on the aerodynamic characteristics of square cylinders with rounded corners
Authors: Miran Sajjad , Sohn Chang Hyun 
Published: December 2015

Purpose
– The purpose of this paper is to focus on the variation of wake structures and aerodynamic forces with changes in the cylinder corner radius and orientation.

Design/methodology/approach
– Numerical simulations were performed for flow past a square cylinder with different corner radii placed at an angle to the incoming flow. In the present study, the rounded corner ratio R/D=0 (square cylinder), 0.1, 0.2, 0.3, and 0.4 (where R is the corner radius and D is the characteristic dimension of the body) and the angle of incidence α in the range of 0°-45° were considered.

Findings
– The numerical model was validated by comparing the present results with results in the available literature, and they were found to be in good agreement. The critical incidence angle for the rounded corner cylinder – corresponding to the minimum mean drag coefficient (C

D
), the minimum root mean square value of the lift coefficient C

L,RMS), and the maximum Strouhal number – shifted to a lower incidence angle compared with the sharp corner square cylinder. The minimum drag and lift coefficient at R/D=0 were observed for the critical incidence angle αcri=12°, whereas for R/D=0.1-0.4, the minimum drag and lift coefficient were found to be within the range of 5°-10° for α.

Originality/value
– The presented results shows the importance of the incidence angle and rounded corners of the square cylinder for reduction of aerodynamic forces. The two parameters support the shear layer flow reattachment on the lateral surface of the cylinder, have a strong correlation with the reduction of the wake width, and hence reduced the values of C

D
and C

L
.
Nanofluid flow past an impulsively started vertical plate with variable surface temperature
Authors: Vemula Rajesh , Chamkha A J , M. P. Mallesh 
Published: December 2015

Purpose
– The purpose of this paper is to focus on the numerical modelling of transient natural convection flow of an incompressible viscous nanofluid past an impulsively started semi-infinite vertical plate with variable surface temperature.

Design/methodology/approach
– The problem is governed by the coupled non-linear partial differential equations with appropriate boundary conditions. A robust, well-tested, Crank-Nicolson type of implicit finite-difference method, which is unconditionally stable and convergent, is used to solve the governing non-linear set of partial differential equations.

Findings
– The local and average values of the skin-friction coefficient (viscous drag) and the average Nusselt number (the rate of heat transfer) decreased, while the local Nusselt number increased for all nanofluids, namely, aluminium oxide-water, copper-water, titanium oxide-water and silver-water with an increase in the temperature exponent m. Selecting aluminium oxide as the dispersing nanoparticles leads to the maximum average Nusselt number (the rate of heat transfer), while choosing silver as the dispersing nanoparticles leads to the minimum local Nusselt number compared to the other nanofluids for all values of the temperature exponent m. Also, choosing silver as the dispersing nanoparticles leads to the minimum skin-friction coefficient (viscous drag), while selecting aluminium oxide as the dispersing nanoparticles leads to the maximum skin-friction coefficient (viscous drag) for all values of the temperature exponent m.

Research limitations/implications
– The Brinkman model for dynamic viscosity and Maxwell-Garnett model for thermal conductivity are employed. The governing boundary layer equations are written according to The Tiwari-Das nanofluid model. A range of nanofluids containing nanoparticles of aluminium oxide, copper, titanium oxide and silver with nanoparticle volume fraction range less than or equal to 0.04 are considered.

Practical implications
– The present simulations are relevant to nanomaterials thermal flow processing in the chemical engineering and metallurgy industries. This study also provides an important benchmark for further simulations of nanofluid dynamic transport phenomena of relevance to materials processing, with alternative computational algorithms (e.g. finite element methods).

Originality/value
– This paper is relatively original and illustrates the influence of variable surface temperature on transient natural convection flow of a viscous incompressible nanofluid and heat transfer from an impulsively started semi-infinite vertical plate.
An efficient discontinuous Galerkin method for two-phase flow modeling by conservative velocity projection
Authors: Jamei Mehdi , Ghafouri H 
Published: December 2015

Purpose
– The purpose of this paper is to present a novel sequential implicit discontinuous Galerkin (DG) method for two-phase incompressible flow in porous media. It is based on the wetting phase pressure-saturation formulation with Robin boundary condition (Klieber and Riviere, 2006) using H(div) velocity projection.

Design/methodology/approach
– The local mass conservation and continuity of normal component of velocity across elements interfaces are enforced by a simple H(div) velocity projection in lowest order Raviart-Thomas (RT0) space. As further improvements, the authors use the weighted averages and the scaled penalties in spatial DG discretization. Moreover, the Chavent-Jaffre slope limiter, as a consistent non-oscillatory limiter, is used for saturation values to avoid the spurious oscillations.

Findings
– The proposed model is verified by a pseudo 1D Buckley-Leverett problem in homogeneous media. Two homogeneous and heterogeneous quarter five-spot benchmark problems and a random permeable medium are used to show the accuracy of the method at capturing the sharp front and illustrate the impact of proposed improvements.

Research limitations/implications
– The work illustrates incompressible two-phase flow behavior and the capillary pressure heterogeneity between different geological layers is assumed to be negligible.

Practical implications
– The proposed model can efficiently be used for modeling of two-phase flow in secondary recovery of petroleum reservoirs and tracing the immiscible contamination in porous media.

Originality/value
– The authors present an efficient sequential DG method for immiscible incompressible two-phase flow in porous media with improved performance for detection of sharp frontal interfaces and discontinuities.
Assessing users satisfaction with web digital library: the case of Universiti Teknologi MARA
Authors: Masrek Mohamad Noorman , Gaskin James Eric 
Published: December 2015

Purpose
– The purpose of this paper is to examine the determinants of user satisfaction in the context of academic web digital library (DL). A model based on the re-specified information system success model was developed and tested using the structural equation modeling (SEM) technique.

Design/methodology/approach
– The study employed survey research methodology with self-administered questionnaire as the research instrument. The questionnaire was developed based on the instruments used by previous researchers. The population of the study was students enrolled for the bachelor’s degree in the Faculty of Information Management, Universiti Teknologi MARA, Malaysia. These students were chosen because of researcher’s easy access to the sampling frame. Descriptive analysis and inferential analysis which include SEM were executed using IBM SPSS and AMOS statistical software.

Findings
– The findings indicate that information quality, systems quality, service quality, perceived usefulness, perceived ease of use and cognitive absorption are significant predictor of users’ satisfaction with the web DL.

Research limitations/implications
– Instead of collecting data from students from various faculties, this study only covered students enrolled in one faculty. In the same light, as the respondents were from one faculty, they only report their experience of using one DL. Given these limitations, the results obtained are narrowed in terms of generalizability. The second limitation of the study is related to the predictor variables which only focussed on six variables only.

Practical implications
– From the practical viewpoint, the instrument that has been developed can be used as a diagnostic tool for continuous improvements of the DL.

Originality/value
– From the theoretical viewpoint, the study has developed an empirical based framework that depicts critical factors influencing DL satisfaction. Researchers specializing on the assessment of DL effectiveness can consider adopting the framework for future studies. Alternatively, the framework can be further extended by integrating other variables such as users’ characteristics or organizational characteristics.
Using webcasts for student presentations: a case study
Authors: Ortaçtepe Deniz 
Published: December 2015

Purpose
– Adopting Davis’ (1989) technology acceptance model (TAM), the purpose of this paper is to investigate the perceived differences between asynchronous presentation tools (webcasts) and in-person presentations in a graduate program designed for the professional development of English as a foreign language (EFL) teachers at a private university in Turkey.

Design/methodology/approach
– Data were collected for the three different types of presentations (i.e. in-person, video, and Prezi webcasts) the students performed in four different courses throughout the 2013-2014 academic year.

Findings
– The analysis of the data coming from a three-part questionnaire revealed that students preferred in class presentations for learning purposes but agreed that webcasts were higher in quality as they included audio-visual materials. This study also concluded that for procedural knowledge that came from hands-on activities, students preferred in-person presentations, while for conceptual knowledge, Prezi webcasts were more preferred as they allocated time for students to reflect, do more research on, and effectively contribute to online discussions.

Research limitations/implications
– The data came from questionnaires; had there been interviews with the students, more insights could have been gained into their perceptions of webcasts as well as how the students actually used them for learning purposes.

Originality/value
– The studies specifically focussing on the use of audio and video podcasts/webcasts integrated these tools as supplementary materials to course content in traditional lectures. Yet, the use of webcasts as a student presentation tool rather than a duplicate of teachers’ lectures or supplementary materials still remains unknown especially in relation to the extent to which individuals’ acceptance of this instructional technology.
HOLDINGS OF NATIONAL AND LOCAL GOVERNMENTS IN COMPANIES IN FINLAND: PERSISTENCE AND CHANGE IN THE LONGER TERM
Authors: AHONEN Pertti 
Published: December 2015

ABSTRACTApplying an approach of neo‐institutional research, this article examines the history of company holdings of the national government and local governments in Finland in the longer term. The article examines the genealogy of the institutional forms of these holdings, the diffusion, adoption and adaptation of these forms, and the political legitimacy of new forms and the political de‐legitimation of earlier forms. For theory, the results indicate that the individual tailoring of institutional forms offers flexibility but increases complexity. For practice, the results suggest that the company form may too easily marginalize alternative institutional forms such as co‐operatives, associations, and foundations.
ON THE EMERGENCE OF NON‐PROFIT FIRMS AS ALTERNATIVES TO THE GOVERNMENT*
Authors: MIKAMI Kazuhiko 
Published: December 2015

ABSTRACTIt is well known that many non‐profit firms coexist with government firms in industries that provide collectively consumed goods and services, such as education, healthcare, social services, and art and culture. This paper explores the specific circumstances under which non‐profit firms can emerge as alternatives to the government. We show that a non‐profit firm emerges only when the residents’ median preference for a collective good is significantly low. This finding implies that, somewhat paradoxically, a non‐profit firm emerges to replace the government and provide a collective good only when the majority of residents consider the good non‐essential.
The Residual-Based Predictiveness Curve: A Visual Tool to Assess the Performance of Prediction Models
Authors: Casalicchio Giuseppe , Bischl Bernd , Boulesteix Anne-Laure , Schmid Matthias 
Published: December 2015

Summary
It is agreed among biostatisticians that prediction models for binary outcomes should satisfy two essential criteria: first, a prediction model should have a high discriminatory power, implying that it is able to clearly separate cases from controls. Second, the model should be well calibrated, meaning that the predicted risks should closely agree with the relative frequencies observed in the data. The focus of this work is on the predictiveness curve, which has been proposed by Huang et al. (Biometrics 63, 2007) as a graphical tool to assess the aforementioned criteria. By conducting a detailed analysis of its properties, we review the role of the predictiveness curve in the performance assessment of biomedical prediction models. In particular, we demonstrate that marker comparisons should not be based solely on the predictiveness curve, as it is not possible to consistently visualize the added predictive value of a new marker by comparing the predictiveness curves obtained from competing models. Based on our analysis, we propose the “residual-based predictiveness curve” (RBP curve), which addresses the aforementioned issue and which extends the original method to settings where the evaluation of a prediction model on independent test data is of particular interest. Similar to the predictiveness curve, the RBP curve reflects both the calibration and the discriminatory power of a prediction model. In addition, the curve can be conveniently used to conduct valid performance checks and marker comparisons.
Possible pharmacotherapy for nifedipine‐induced gingival overgrowth: 18α‐glycyrrhetinic acid inhibits human gingival fibroblast growth
Authors: Takeuchi R , Hiratsuka K , Arikawa K , Ono M , Komiya M , Akimoto Y , Fujii A , Matsumoto H 
Published: December 2015

Background and PurposeThis investigation aimed to establish the basis of a pharmacotherapy for nifedipine‐induced gingival overgrowth. Gingival overgrowth has been attributed to the enhanced growth of gingival fibroblasts. In this study, we investigated the effects of 18‐α‐glycyrrhetinic acid (18α‐GA) on growth, the cell cycle, and apoptosis and on the regulators of these processes in gingival fibroblasts isolated from patients who presented with nifedipine‐induced gingival overgrowth.Experimental ApproachGingival fibroblasts were cultured in medium containing 1% FBS with/without 10 μM 18α‐GA for 24 or 48 h, and the cell number, cell cycle phase distribution, relative DNA content, apoptotic cell number and morphological characteristics of the cells undergoing apoptosis were measured together with the levels of proteins that regulate these processes and the level of caspase activity.Key Results18α‐GA significantly decreased cell numbers and significantly increased the percentage of cells in the sub‐G1 and G0/G1 phases of the cell cycle and the number of apoptotic cells. Nuclear condensation and fragmentation of cells into small apoptotic bodies appeared in the fibroblasts treated with 18α‐GA. In addition, 18α‐GA significantly decreased the protein levels of cyclins A and D1, CDKs 2 and 6, phosphorylated Rb (ser780 and ser807/811), Bcl‐xL and Bcl‐2 and increased the protein levels of p27, cytosolic cytochrome c, pro‐caspase‐3, and cleaved caspase‐3 and the activities of caspases 3 and 9.Conclusions and Implications18α‐GA inhibited gingival fibroblast growth by suppressing the G1/S phase transition and inducing apoptosis. In conclusion, 18α‐GA may be used as a pharmacotherapy for nifedipine‐induced gingival overgrowth.