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Objectives: Aim of this work was to characterize possible central anatomical configurations in which a future artificial lung (AL) could be connected, in terms of oxygenation performance.Methods: Pulmonary and systemic circulations were simulated using a numerical and an in vitro approach. The in vitro simulation was carried out in a mock loop in three phases: (1) normal lung, (2) pulmonary shunt (50% and 100%), and (3) oxygenator support in three anatomical configurations: right atrium-pulmonary artery (RA-PA), pulmonary artery-left atrium (PA-LA), and aorta-left atrium (Ao-LA). The numerical simulation was performed for the oxygenator support phase. The oxygen saturation (SO2) of the arterial blood was plotted over time for two percentages of pulmonary shunt and three blood flow rates through the oxygenator.Results: During the pulmonary shunt phase, SO2reached a steady state value (of 68% for a 50% shunt and of nearly 0% for a 100% shunt) 20 min after the shunt was set. During the oxygenator support phase, physiological values of SO2were reached for RA-PA and PA-LA, in case of a 50% pulmonary shunt. For the same conditions, Ao-LA could reach a maximum SO2of nearly 60%. Numerical results were congruous to the in vitro simulation ones.Conclusions: Both in vitro and numerical simulations were able to properly characterize oxygenation properties of a future AL depending on its placement. Different anatomical configurations perform differently in terms of oxygenation. Right to right and right to left connections perform better than left to left ones.

The authors discuss the use of quantum technology in the field of cyber security. They mention the current state of quantum computing including various myths, how it can be used in cryptographic attacks and how to protect against such attacks, and the need to protect quantum computers.

•LightGBDT application for travel mode choice prediction is proposed.•Predictive performance of LightGBDT is compared with four traditional machine learning models.•Prediction results showed LightGBDT model achieved better performance.•Feature sensitivity and SHAP summary analysis are conducted to explore the significant factors influencing the travelers’ mode preferences.•Study could provide analysts with key insights for effective transportation planning.

Purpose: To reduce financial and human losses, managing risks associated with earthquakes is essential in practice. However, in using common risk management methods, experts are often faced with ambiguities that can create profound challenges for risk management. Therefore, it is necessary to develop a logical and straightforward risk assessment model to provide scientific and accurate answers to complex problems. This study aims to recommend an innovative combined method based on the probability-impact (P-I) approach and intuitionistic fuzzy set theory to identify and prioritize the essential earthquake risks associated with worn-out urban fabrics in the context of Iran. Design/methodology/approach: The opinions of 15 experts in the fields of civil engineering and urban construction were gathered during brainstorming sessions. These brainstorming sessions were conducted to determine the probability of risks and the effect of identified risks. After calculating the severity of risks using the P-I approach and converting them to intuitionistic fuzzy sets, the risks were measured and prioritized based on their individual scores. Findings: The study results indicated that risk of damage due to buildings’ age and flooding risk had the highest and lowest priorities in causes of financial damage, respectively. Furthermore, the risk of damage due to building quality (demolition) and building age was the most important. The risk of flooding and damage to communication networks has the lowest importance among causes of fatalities in worn-out urban fabrics. Originality/value: The study findings and recommendations can be served as a policy and consultative instrument for the relevant stakeholders in the area of urban management.

In 1951, NSF International, then the National Sanitation Foundation, was approached by the Thermoplastics Division of the Society of the Plastics Industry to initiate a research study related to the [...]

Coarse grid projection (CGP) is a multiresolution technique for accelerating numerical calculations associated with a set of nonlinear evolutionary equations along with stiff Poisson’s equations. In this article, we use CGP for the first time to speed up incompressible magnetohydrodynamics (MHD) flow simulations. Accordingly, we solve the nonlinear advection–diffusion equation on a fine mesh, while we execute the electric potential Poisson equation on the corresponding coarsened mesh. Mapping operators connect two grids together. A pressure correction scheme is used to enforce the incompressibility constrain. The study of incompressible flow past a circular cylinder in the presence of Lorentz force is selected as a benchmark problem with a fixed Reynolds number but various Stuart numbers. We consider two different situations. First, we only apply CGP to the electric potential Poisson equation. Second, we apply CGP to the pressure Poisson equation as well. The maximum speed-up factors achieved here are approximately 3 and 23, respectively, for the first and second situations. For the both situations, we examine the accuracy of velocity and vorticity fields as well as the lift and drag coefficients. In general, the results obtained by CGP are in an excellent to reasonable range of accuracy. The CGP results are significantly more accurate compared to the numerical simulations of the advection–diffusion and electric potential Poisson equations on pure coarse scale grids.

Colored wastewater is the most important problem of textile manufacturing factories, because it contains pollutants with complex structure and toxic, carcinogenic, and mutagenic properties which are non-biodegradable and sustainable in the environment. Reactive Red 198 (RR198) is one of the types of azo dyes which are widely used in the textile industries. Therefore, in this study, the rate of degradation and mineralization of RR198 by UV/US/H2O2/O3hybrid process was investigated. Influencing factors including: initial dye concentration (100, 200, 300, 400, 500 mg/L), contact time (12.5, 30, 47.5, 65, 82.5 min), pH (3, 5, 7, 9, 11), UV (125-W), H2O2(10, 20, 30, 40, 50 mg/L), US (160 KHz) and O3(33 mg/(L·min)) on the removal and mineralization efficiency of RR198 were investigated. Optimization and modeling of the process was done by CCD method. Based on the results of ANOVA analysis, most effective parameters on the RR198 removal efficiency were ozone, US, UV, time, initial dye concentration, pH, and H2O2, respectively, with an impact percentage of 96.86 and less than 1% for ozone and the rest parameters, respectively. Highest removal efficiency of RR198 was obtained by UV/US/H2O2/O3hybrid process. Optimal conditions for dye removal including: initial dye concentration of 200 mg/L, reaction time of 34 min, H2O2concentration of 27 mg/L and pH of seven were determined in the presence of ozone gas, UV, and US waves. In these conditions, the removal efficiency of RR198 and TOC were estimated to be 100 and 40.5, respectively. UV/US/H2O2/O3hybrid process as an advanced oxidation process (AOP) with advantages such as high performance and speed, no sludge production and toxic residues in the treated effluent containing hard biodegradable compounds such as RR198 from aqueous solutions, so can be recommended and used.

This paper deals with the optimal state observer of nonlinear systems based on a new strategy. Despite development in state prediction for linear systems, state prediction for nonlinear systems continues to be difficult. To acquire a future estimate of the system states, this article first accomplished Taylor series expansion of states in their receding horizons to any given order, and then produced an analytic solution for the prediction error issue, resulting in a closed-form for the nonlinear optimal observer. In proposed observer, the observer gain was optimally chosen among gains obtained from the analytic solution of prediction error problem and satisfied stability condition. Finally, the qualitative simulation results showed the effectiveness of proposed method in the state observation.

Q1N samples with different degrees of tempering were produced and changes in MBN energies in non-stressed and stressed samples was investigated. It was observed that while MBN energy decreased with increasing degree of tempering, it increased with applied uniaxial stress and the two opposing effects cannot be easily separated. MBN energy increased with stress along RD and decreased in the transverse direction (TD). Therefore, the ratio of MBN energy in RD to TD was examined. The value of the ratio at 0.3 T was successfully shown to be strongly correlated with applied uniaxial tensile stress level, regardless of the degree of tempering (pinning site density) in Q1N samples.

Purpose: To design, control and evaluate photovoltaic (PV) systems, an accurate model is required. Accuracy of PV models depends on model parameters. This study aims to use a new algorithm called improved social spider algorithm (ISSA) to detect model parameters. Design/methodology/approach: To improve performance of social spider algorithm (SSA), an elimination period is added. In addition, at the beginning of each period, a certain number of the worst solutions are replaced by new solutions in the search space. This allows the particles to find new paths to get the best solution. Findings: In this paper, ISSA is used to estimate parameters of single-diode and double-diode models. In addition, effect of irradiation and temperature on I–V curves of PV modules is studied. For this purpose, two different modules called multi-crystalline (KC200GT) module and polycrystalline (SW255) are used. It should be noted that to challenge the performance of the proposed algorithm, it has been used to identify the parameters of a type of widely used module of fuel cell called proton exchange membrane fuel cell. Finally, comparing and analyzing of ISSA results with other similar methods shows the superiority of the presented method. Originality/value: Changes in the spider's movement process in the SSA toward the desired response have improved the algorithm's performance. Higher accuracy and convergence rate, skipping local minimums, global search ability and search in a limited space can be mentioned as some advantages of this modified method compared to classic SSA. [ABSTRACT FROM AUTHOR]

Background Determine attitude of young people to reproductive health issues can somewhat predict their behavior in this area. This helps us in planning future on reproductive health. The aim of this study was to determine the attitude of reproductive health and related factors among Iranian students in public universities in Iran.Method A cross-sectional study was carried out. The tool was developed based on a literature review to find out about reproductive health attitudes and sociodemographic factors associated. The face and content validity of the questionnaire was performed using expert judgment. Cronbach’s coefficient and test–retest were used to determine the reliability. Data were analyzed using the Statistical Package for Social Sciences software by independent ttest, ANOVA, and multiple linear regression.Results Out of 461 respondents, the majority of students were nonmedical sciences (81.1%). The main sources of information for reproductive health awareness were the media (40%); 54.9% disagreed with having premarital sex in both sexes, while only 36% agreed to postpone sexual activity until marriage in order to prevent sexually transmitted diseases. Moreover, 64% believed that contraception would cause infertility in the future. The majority found the need for reproductive health services and education essential for single youth. Multiple regression showed a poor reproductive health attitude in nonmedical students, families who did not talk about boy–girl relationships, as well as in satellite users and hookah consumers.Conclusion The students’ level of attitude on reproductive health was not satisfactory. Intervention programs related to reproductive health taking into account the cultural aspects of Iranian society can protect young people from risky behaviors and unwanted pregnancies by creating a positive attitude.

Transient thyroid function abnormalities at birth exhibit intellectual developmental and cognitive disorders in adulthood. Given the well-known effects of physical activity and sex hormones on cognitive functions and brain-derived neurotrophic factor (BDNF), the present study examined the effects of treadmill exercise, sex hormones, and the combined treatment on learning and memory and hippocampal BDNF levels in transient congenital hypothyroid rats. To induce hypothyroidism, 6-propyl-2-thiouracil was added to the drinking water from the 6th day of gestation to the 21st postnatal day (PND). From PNDs 28 to 47, female and male pup rats received 17β-estradiol and testosterone, respectively, and about 30 min later, they were forced to run on the treadmill for 30 min once a day. On PNDs 48–55, spatial learning and memory of all rats tested in the water maze, which followed by measurement of BDNF in the hippocampus. Results showed that developmental hypothyroidism induced significant deficits in spatial learning and memory and hippocampal BDNF in both male and female rats. In both male and female hypothyroid rats, exercise and exercise plus sex hormones, but not sex hormones alone alleviated learning and memory deficits and all treatments (exercise, sex hormones, and the combined treatment) increased hippocampal BDNF. These disconnects in the effects of exercise, sex hormones and the combined treatment on behavioral and neurochemical outcomes suggest that a neurochemical mechanism other than hippocampal BDNF might contribute in the ameliorating effects of exercise on learning and memory deficits induced by developmental thyroid hormone insufficiency.

A novel, high-efficiency, and cost-effective series of sulfonated poly(phthalazinone ether ketone)/sulfonated titanium dioxide@toluene diisocyanate@ethylenediamine (SO3H−TiO2@TDI@EN-SO3H) nanocomposite membranes is designed to enhance the proton conductivity and methanol barrier of the proton exchange membrane (PEM). The nanocomposite membranes were prepared via a facile one-step process of the solution casting method. The presence of organic–inorganic SO3H–TiO2@TDI@EN-SO3H nanoparticles improved the performance of the nanocomposite membranes in terms of mechanical stability, proton conductivity, methanol permeability, and selectivity. We used toluene diisocyanate (TDI) as a linker to exploit the properties of sulfonated TiO2and sulfonated ethylenediamine (EN-SO3H) nanoparticles. These nanoparticles act as Lewis and Brønsted acids simultaneously because of the presence of sulfonamide, TiO2, and SO3H groups, which increase the kinetics of the reaction between the membrane and electrode, improving the performance of the direct methanol fuel cell (DMFC). The DMFC, which is assembled using the nanocomposite membrane with 5 wt % SO3H–TiO2@TDI@EN-SO3H nanoparticle (MSN5) membrane, exhibited a maximum power density of 59.22 mW cm–2during testing because of high proton conductivity and low methanol permeability. The MSN5membrane is a promising PEM for DMFCs.

Coarse-grid projection (CGP) multigrid techniques are applicable to sets of equations that include at least one decoupled linear elliptic equation. In CGP, the linear elliptic equation is solved on a coarsened grid compared to the other equations, leading to savings in computation time and complexity. One of the most important applications of CGP is when a pressure correction scheme is used to obtain a numerical solution to the Navier–Stokes equations. In that case, there is an elliptic pressure Poisson equation. Depending on the pressure correction scheme used, the CGP method and its performance in terms of acceleration rate and accuracy level vary. The CGP framework has been established for non-incremental pressure projection techniques. In this article, we apply CGP methodology for the first time to incremental pressure correction schemes. Both standard and rotational forms of the incremental algorithms are considered. The influence of velocity Dirichlet and natural homogenous boundary conditions in regular and irregular domains with structured and unstructured triangular finite element meshes is investigated. L2norms demonstrate that the level of accuracy of the velocity and the pressure fields is preserved for up to three levels of coarsening. For the test cases investigated, the speedup factors range approximately from 1.2 to 102.7.

The application of electrical fields in emulsion separation in the biodiesel production process was investigated. Two sets of experiments were performed; first, electrostatic demulsification on water-in-biodiesel model emulsions was carried out. These emulsions were prepared using biodiesel derived from soybean oil and castor oil and with a water content of 10% w/w. The electrostatic separation of model emulsions showed an acceptable efficiency with the final water contents of less than 1% w/w in most cases. The second phase of the study was carried out by producing castor oil biodiesel via transesterification in the laboratory. The separation process, after reaction and product (biodiesel) washing, was performed by electrostatic destabilization at various electrical fields. The results of the electrostatic demulsification were compared with centrifugation and decanting as conventional separation techniques. Promising results were obtained in the separation of biodiesel from water and glycerol by the application of electrostatic treatment.

We discuss coarse grid projection (CGP) methodology as a guide for partial mesh refinement of incompressible flow computations for the first time. Based on it, if for a given spatial resolution the numerical simulation diverges or the velocity outputs are not accurate enough, instead of refining both the advection–diffusion and the Poisson grids, the CGP mesh refinement suggests to only refine the advection–diffusion grid and keep the Poisson grid resolution unchanged. The application of the novel mesh refinement tool is shown in the cases of flow over a backward-facing step and flow past a cylinder. For the backward-facing step flow, a three-level partial mesh refinement makes a previously diverging computation numerically stable. For the flow past a cylinder, the error of the viscous lift force is reduced from 31.501 to 7.191% (with reference to the standard mesh refinement results) by the one-level partial mesh refinement technique.

Objectives: Contemporary therapies for chronic kidney disease patients encompass a wide range of hemodialysis treatments, most of which rely greatly on dialyzers and hemofilters. The filtration process taking place in these devices with respect to the hemodynamic characteristics of the flow, has not yet been fully investigated. This study aims at improving the understanding of hemodynamics in a dialyzer by employing experimental methods and mathematical models.Methods: A semiempirical model has been formulated based on the principles of hemodynamics, considering the dominant phenomena of filtration-backfiltration and the corresponding driving forces. An in vitro hemodialysis circuit was accordingly assembled for experimental data acquisition, and subsequently for model validation. The circuit consisted of two dialyzers arranged in sequential order, in pursuance of increasing the number of sampling points. Fresh, heparinized porcine blood was used throughout the course of this study. Pressure and flow data obtained from in vitro investigations with the hemodialysis circuit were used as an input for the semiempirical model.Findings: The model predicted a substantial divergence in the course of hematocrit value along the length of the hollow fibers, which is corroborated by the experimental data. Particularly in certain operational conditions, hematocrit rose from 25% at the inlet to 65% halfway along the dialyzers’ length, to end at 30% at the outlet.Conclusion: Validation of the model’s predictions with experimental data demonstrated a very good agreement, confirming the model’s accuracy. Potential implementation of the model in clinical practice in the future might contribute greatly to an improved hemodialysis experience.

Blinded randomized controlled trial.

In recent years, consumer interest in radiant floor heating has increased significantly, sparking a wide variety of radiant floor heating products on the market. Plumbing and mechanical codes require these [...]

In this paper, the electrical conductivity measurements of four types of crude oils at reservoir conditions were carried out using an in-house-developed pressurized cell. The newly introduced apparatus has the capability of performing electrical conductivity measurements of various reservoir fluids at high-pressure, high-temperature (HPHT) conditions. The cell can be pressurized with an inert gas to be far enough above the bubble points (Pb) of crude oils. The alternate voltage (AV) cycle methodology was applied to perform the experiments. In this method, the subtraction of electrical currents when the voltage alternated between two specified values (0 and 2 V in this work) was used to calculate the conductivity. The reliability of the methodology and equipment in making conductivity tests has been verified by comparing the conductivity results to the “rest conductivity” values measured via a standard method. Variation of crude oil electrical conductivity showed a strong relation to the physical and chemical properties of the reservoir fluids, including the electrical nature of compounds in oils and viscosity of fluids. The experimental data were fitted well to the Arrhenius model with a clear break point at a certain temperature for each oil, which can be linked to the structural change of the fluids at the mentioned temperatures.

The deteriorating competitive edge of U.S. corporations is attributable to outdated management theories still employed by American companies that promote a feeling of insecurity among employees, confuse short-term achievements with real success, and tend to create confrontations with labor committees and trade-unions. Of these faults, perhaps the emphasis on short-term goals has had the most detrimental effects on U.S. business behavior; among these effects are: a failure to innovate, a lack of research and development, and an inability to effectively plan long-range corporate goals or investment policies. Suggestions for improving the management of U.S. companies include: emphasizing job creation, dissolving formal (and artificial) barriers to employee promotion, and concentrating on long-term planning and development.

This research shows different hard Ti-based coatings deposited over steel substrates using the physical vapor deposition (PVD) method. The graded coating of the three produced Ti, TiN and TiCN were assessed using phase composition analysis and spectroscopy study. The microstructure characterization was studied by X-ray Photoelectron spectroscopy (XPS), Scanning Electron Microscopy (SEM), and transmission electron microscopy (TEM). The results show that integrating Ti interlayer with subsequent TiN/TICN layers can be considered a suitable way to yield hard Ti-based coating with enhanced mechanical and tribological behavior due to nitride and carbonitride phases formed from the breakdown of carbon and nitrogen atoms. The elastic modulus and hardness of all layers were identified by nanoindentation and utilized to achieve yield strength. Later, the curvature of the unloading step and elastic properties are used for finding flow behavior parameters in terms of work hardening factors (n and K). The attained findings extracted from the load–displacement curve of both nanoindentation and nano scratch were analyzed to examine the microscopic performance of all three Ti, TiN, and TiCN coatings. Scratch mechanisms analysis in all coatings shows that the main failures in samples are caused by tensile stress stemming from Hertzian cracks. However, as the force increases, the coating surface undergoes an incremental deformation, and failure mode varies to interfacial spallation.

Background: The inhibitory activities of vitamins K2against clinical isolates of quinolone-resistant and methicillin-resistant Staphylococcus aureus(QR-MRSA) are unclear. The main aim is to better understand of inhibitory activities of vitamins K2,multi-locus sequence typing (MLST), SCCmec,and spatyping in clinical isolates of QR-MRSA on those mutation and gene expressions. Materials and methods: After collecting S. aureusclinical isolates and detecting QR-MRSA, the genes encoding norA, grlA, grlB, gyrA, and gyrBwere sequenced. After treating isolates by vitamin K2, isolates were prepared to measure norA, grlA, grlB, gyrA, and gyrBgene expression. The quantitative-real-time PCR was used to measure the expression of efflux pump genes. Results: QR-MRSA, MDR, and XDR strains were reported in 59.4%, 73.9%, and 37.6% of isolates, respectability. SCCmecIV (36.5%) and SCCmecV (26.8%) had the highest frequency. Thirty-nine spatypes were identified, t021, t044, and t267 types most prevalent in QR-MRSA isolates. ST22 and ST30 dominated the invasive, drug-resistant isolates and QR-MRSA. In 24 h incubated isolates, the most noticeable change of gene expression with vitamin K2was that the norA, gyrA, and grlBgenes were highly repressed. However, the down-regulation of grlAat 24 h after being treated by vitamin K2was more than another gene. Further, a significant decrease was observed in QR-MRSA-treated isolates compared to un-treated isolates. In other words, norA, grlA, grlB, gyrA, and gyrBgenes were less suppressed by QR-MRSA (p≤ 0.01, p≤ 0.05). Conclusion: Vitamin K2has significant inhibitory effects on the genes responsible for resistance to fluoroquinolone antibiotics. However, a subminimum inhibitory concentration (sub-MIC) level of vitamin K2was delayed but did not completely inhibit norA, grlA, grlB, gyrA, and gyrBgenes in MRSA strains.

Since 1981, the number of US burn centers has decreased by 29%, resulting in more long distance referrals to remaining facilities. Air transport is often the only feasible method for remote patients to reach few remaining burn centers. A significant proportion of flown-in patients have minor burns and are discharged within 24 hours, representing potential over-utilization of resources with increased cost to the healthcare system for no perceptible benefit. We explored factors associated with air transport of burns and opportunities for system improvement. Retrospective review of burn patients transferred by air to regional burn center between January 2003 and June 2013. Demographic, injury and clinical outcome data were acquired from the institutional Burn Registry. Minor burns constituted 17.7% of all flown admits (236/1331). Children were more likely to be included in this cohort at 32% vs 21.6% of adults (P= .0004). The overtriaged cohort had significantly lower % total BSA than accurately triaged cohort (3.3% vs 15%; P= .0001). Subjects with electrical burn injury were twice as likely to be overtriaged than accurately triaged (10.6% vs 5%; P= .002). The average % total BSA in the overtriaged group was 3.3%; the face was most common area burned (47.7%). The average estimate of charges for transfer was between $25,000 and 30,000/patient. The incidence of overtriage among flown-in burn patients, approximately 20%, represents substantial unnecessary healthcare expenditure. Improved burn care education, incentives to increase use of telemedicine, and modification of American Burn Association guidelines to include consultation with a burn center rather than automatic transfer are needed to reduce this cost to the healthcare system.

Generative modelling has become a promising use case for near-term quantum computers. Due to the fundamentally probabilistic nature of quantum mechanics, quantum computers naturally model and learn probability distributions, perhaps more efficiently than can be achieved classically. The quantum circuit Born machine is an example of such a model, easily implemented on near-term quantum computers. However, the Born machine was originally defined to naturally represent discretedistributions. Since probability distributions of a continuous nature are commonplace in the world, it is essential to have a model which can efficiently represent them. Some proposals have been made in the literature to supplement the discrete Born machine with extra features to more easily learn continuous distributions; however, all invariably increase the resources required. In this work, we discuss the continuous variableBorn machine, built on the alternative architecture of continuous variable quantum computing, which is much more suitable for modelling such distributions in a resource-minimal way. We provide numerical results indicating the model’s ability to learn both quantum and classical continuous distributions, including in the presence of noise.

Observation, communication, team working, judgment, and decision making skills are important reflective thinking skills for teachers. The main purpose of the present paper is to identify the ways of improving teachers’ reflective thinking skills. To achieve this goal reflective thinking skills between experienced and inexperienced teachers are compared in different levels of reflective thinking. The Profile of Reflective Thinking Attributes (PRTA) Instrument and Reflective Thinking Attributes (RTA) Instrument are introduced to identify teachers’ reflective thinking levels.

Observation, communication, team working, judgment, and decision making are important teaches reflective thinking skills that are required for teachers if they want to be reflective thinker. This paper proposes two instruments which are Reflective Thinking Open-Ended Questionnaire and Interview Questionnaire to measure teachers’ reflective thinking skills. The Reflective Thinking Open-Ended Questionnaire allows teachers to answer the questions in their own words in explaining the meaning of reflective thinking and understanding the gaps if there are between teachers’ reflective thinking skills and the reflective thinking skills that they need in their teaching. The Interview Questionnaire is used to support depth understanding the skills that teachers use in their teaching. Measuring teachers’ reflective thinking skills by these instrument help to identify teachers’ reflective thinking weakness and strength and find the ways for improving their reflecting thinking.

Derivation is one of the fundamental concepts in the learning of university mathematics. It is a prerequisite for other concepts in undergraduate level and its traces are visible in the majority of mathematical courses at university level. Students have difficulties in the learning of this concept which mostly come back to lack of conceptual understanding. The purpose of this study is to investigate the reasons of difficulties, which faced students in conceptual understanding of derivation. The design of this study is qualitative analysis of open-ended questions, and its subjects consisted of 63 undergraduate students. The findings showed students have serious difficulties in understanding conceptually of derivation. The students’ responds indicated that main reasons of difficulties in conceptual understanding of derivation come back to focusing on symbolic aspect more than embodied aspect, lack of making logical connection between these aspects, and weakness of dealing with generalized question. Findings of this study provide information to undergraduate instructors and students to overcome learning difficulties of derivation.

Machinability of grey cast iron parts can greatly suffer from the formation of carbide at the surface, resulting in a decrease in cutting tool life and higher production costs. Therefore, detection of the hardened layer and its hardness are the key factors in quality control and inspection processes. In the present paper, a number of metallurgical parameters (surface carbide, surface hardness and hardened depth) have been investigated using the non-destructive differential eddy current technique. The results show the high potential of the proposed method as a fast and accurate technique in inspecting and in consequent separation of undesirable parts.

The preeminent limitation of silicone membrane oxygenators is the poor gas permeability compared with microporous hollow fiber oxygenators (MHFO). However, the imponderability of plasma leakage, foam formation, and brittleness are all hazards that result in blood trauma formation, hereby limiting the application of MHFO during long-term oxygenation therapies. Here, we introduce a novel type of pure diffusive capillary-form silicone membrane called silicone hollow sphere. Silicone hollow sphere walls embed hollow microspheres into the core. The lodging of such microspheres promotes a higher gas exchange performance (as a result of the reduction of dense material) without altering the total thickness of capillary walls; thereby the demanded mechanical strength for handling is nevertheless conserved. Out of the same silicone material, seven SiHSp fibers with six different design specifications and a control were constructed to define experimentally the appropriate configuration for subsequent production. Each fiber was used in a miniaturized module oxygenator of a constant effective membrane surface area (Aeffmem= 0.02 m2) and length (L =183 mm) for a fair evaluation. Modules were investigated in vitrowith porcine blood. O2and CO2transfer rates weighed 12.6 mlO2min and 10.4 mlCO2min, respectively, for one type of SiHSp, comparable with microporous polypropylene (OXYPHAN) exhibiting 14.1 mlO2min and 13.2 mlCO2min, respectively, at a maximum blood flow rate (Qmax= 200 mlmin). Silicone hollow sphere fibers show a promising competency to MHFs. They also show an evident dominancy over the conventional silicone fibers, evaluated by the control module, which emphasizes the advantage of this design.

Multivariable calculus is one of the most difficult courses for undergraduate students in many fields of studies. This study used blended learning as a teaching and learning environment to support students’ mathematical thinking and to help students in overcoming their obstacles in the learning of multivariable calculus. The main purpose of this study is to determine the impact of blended learning on the students’ learning of multivariable calculus and in overcoming students’ obstacles. The results revealed that blended learning is an adequate environment since it provides sufficient tools that support students’ mathematical thinking powers to overcome their obstacles in learning multivariable calculus.

This study is part of a project concerned with the students’ obstacles in face-to-face Engineering Mathematics classrooms through mathematical thinking approach. The main data collection for this study was carried out through students’ structured questionnaires of three classes at Universiti Teknologi Malaysia (UTM) in the end of semester. The findings showed that the students’ obstacles from students’ and lecturers’ perspectives are approximately the same and the majority of each group separately believed that two main obstacles in the learning of Engineering Mathematics are imaging and sketching in the 3-dimensions. The analysis showed that for both groups different thinking skills and tools from Creative Problem Solving (CPS) are less important methods that can help students to overcome learning obstacles.

Effective communication and teamwork are two important generic skills requirements for successful engineers. In this study, we used blended learning environment based on mathematical thinking and Creative Problem Solving to support students’ communication and teamwork skills in the learning of multivariable calculus. The main goal of this study is to identify the impact of the blended learning multivariable calculus course on engineering students’ communication and team-working skills. Results indicated that the blended learning multivariable calculus course has positive effects on students’ communication skills. However, the scores of both pre and post-test for students’ teamwork skills remained virtually the same.

Creative Problem Solving as a framework to encourage whole-brain thinking which employs different thinking skills and tools is not sufficiently emphasized in universities. Research findings indicate that for most engineering students, mathematics has always been one of the most difficult courses to study. Previous researches tried to overcome students’ difficulties in the engineering mathematics by using some methods based on supporting mathematical thinking. In this paper, we shall discuss and propose a learning environment for supporting students’ thinking and creative problem solving in engineering mathematics. Blended learning is suggested as an environment to support students’ thinking powers through creative problem solving.

Over the past 20 years, there has been a dramatic increase in the use of autologous fat grafting to treat volume and contour defects in aesthetic and reconstructive surgery. It is generally accepted that fat grafting is safe, with good patient satisfaction. However, there are many procedural variations, and in terms of objective clinical effectiveness, the major disadvantage of this technique remains the unpredictable fat resorption rates and subsequent adverse events. Because of the rapidly evolving nature of this procedure, this review article provides an update on previous reviews by looking at the current evidence base regarding fat graft techniques and their effect on clinical outcome.

In multivariable calculus, the concept of multivariable function is one of the most difficult for undergraduate students to study. The main objective of this study is to establish a model of teaching and learning to support students' mathematical thinking in the learning of two-variable functions through a blended learning environment. The impact of this environment on students' learning of two-variable functions and in overcoming students' obstacles are put forward. Findings revealed that blended learning supports students' mathematical thinking and helps in overcoming additional obstacles in mathematical learning. Poor mathematical knowledge of single-variable functions and poor algebraic manipulations are still the main reasons behind student obstacles in learning two-variable functions.

Many efforts on identifying misconceptions among schools and undergraduate students have been done, but for postgraduates, in particular serviced teachers, are yet to be understood. Researches, thesis writing and publications require substantial level of statistical reasoning for postgraduates. The purpose of this study is to identify and analyze postgraduates' misconceptions in descriptive statistics (central tendency and variability). The instrument was a set of questions design to test statistical reasoning in descriptive statistics. The test was administered to 122 postgraduates who are enrolling in a course on application of statistics in educational research which is a requirement for their master program in education. The misconceptions were analyzed based on the work of various researchers (Lee & Meletiou, 2003; Magina & Cazorla, 2008). This paper describes some similar misconceptions that were found by other researchers; however, some misconceptions on the concept of average were not seen among postgraduates. The overall results show that some postgraduates have poor statistical reasoning skills. This study suggests that statistical reasoning should be taught strategically so as to minimize misconceptions among postgraduate students as well as to empower their statistical reasoning ability.

This paper aims at examining the relationship between achievement goals- mastery and performance goals, metacognition, students' beliefs and academic success of the physics students in University Technology Malaysia (UTM). Regression analysis indicates that metacognition is a full mediator between mastery goals and academic success whilst; students' beliefs are not mediate between mastery goals and academic success. Results of this study can be used to modify the present teaching techniques for physics undergraduate students to meet their learning needs.

Calculus as a prerequisite course to other advanced mathematics courses is one of the important and difficult courses for undergraduate students in many fields of study. Mathematical thinking is an important method to support students in the learning of calculus and specifically multivariable calculus. Researchers endeavour to support student's mathematical thinking in calculus with or without computer-based tools. The main goal of this paper is to illustrate the importance of using computer-based tools for fostering student's mathematical thinking to overcome their obstacles in multivariable calculus.

In Malaysia and also elsewhere in the world the demands for graduates who have employability skills such as ability to think critically, solve problems and can communicate are highly sought in the workplace. In the early 2006, the development of such skills was recognized as integral goals of undergraduate education at Universiti Teknologi Malaysia. Since then rigorous efforts have been made to inculcate these skills amongst the undergraduates. In this paper, we will share some of our experiences in coping with the challenges of changing our teaching practices to accommodate this quest though focusing on communication. For mathematics learning to occur, we believed that students should participate actively in the knowledge construction and be able to take charge of their own learning. Taking these aspects into consideration, we had developed a framework of active learning and used it to guide our instruction in engineering mathematics at UTM. Here we will discuss the strategies that we had designed and employed in engaging students with the subject matter as well as to initiate and support student's thinking and communication in the language of mathematics. Some student's responses that gave indications of their struggle, progress and growth encountered in the research implementation will also be presented.

This study investigated various sources of stress among junior and senior midwifery students in Iran. It also explored the effect of stress on the students’ performance and physical and mental health. Ninety junior and senior midwifery students participated in this survey. Data were collected using self-created questionnaires and analysed using the Statistical Package for the Social Sciences (SPSS). The data showed that the most stressful activity for juniors was nursing care practice. Prenatal health care practice was identified as the second most common cause of stress in juniors. For seniors, nursing care practice and prenatal health care practice were equally stressful. The preceptor (mentor) as well as the clinical setting and staff have been identified as two major factors causing stress, somewhat more in juniors than in seniors. The most common physiological and behavioural demonstrations of stress in the students were palpitation, exacerbated asthma, fatigue, unusual behaviour and dizziness. It is evident that efforts need to be made to minimize the negative effect of stress on students by creating and establishing healthy learning environments.

With the ever-increasing infiltration of the internet into everyday affairs of human life, the monitoring and control of social behaviours of users for the purpose of proper management of society has proved prudent. But, most existing approaches to social behaviour analysis are static and fall short of considering the varieties and differences in cultures and localities. We propose a dynamic approach to extract localised users’ favourite websites through logging the URLs that were accessed by users in places such as universities and government institutions; then by categorising the content of logged websites, our categorised users’ favourite websites were created dynamically. We evaluated our approach in a real setting by dynamically building up a database of users’ favourite websites in a six months period operating in the ICT ministry of Iran. Comparison with famous static URL databases showed the superiority of our approach in catching newly published websites, making our approach more durable in performance.

Function of several variables is one of the most important concepts in mathematics and its applications. The lack of its understanding will cause certain obstacles in the learning of next concepts or even subjects. The researchers at Universiti Teknologi Malaysia (UTM) tend to support students to overcome their deficiencies in the learning of two-variable functions by promoting mathematical thinking. The purpose of this study is to demonstrate how this method can help students in the learning of two-variable functions when they encounter non-routine problems in face-to-face Engineering Mathematics (Multivariable Calculus) course through this method. The data collection for this study was collected from a Multivariable Calculus class at UTM during semester II 2009-2010. Data collection for the study was carried out through written assessments and structured questionnaires. The data analysis reveals that students still display difficulties in their learning. Specifically, students’ common difficulties are: students’ met-before (previous experience), selecting appropriate representation of the three worlds of mathematical thinking, the transition from one world to another world of mathematical thinking, lack of understanding two different embodiments, and lack of understanding two different symbolic for a concept. The findings reveal that the sketching the graph of two-variable functions in 3-dimensions is the greatest difficulty for majority of students in this method. Additionally, the quite entrenching of students in their learning behaviour and styles is the most important reason for the lack of using prompts and questions as guides by students and then no enough effectively of this method.

Distributed denial-of-service (DDoS) attacks on public servers after 2000 have became a serious problem. In the DDoS attacks often seen recently, multiple distributed nodes concurrently attack a single server. To assure that essential network services will not be interrupted, faster and more effective defence mechanisms are needed to protect against malicious traffics, especially SYN floods. One of the problems in detecting SYN flood traffics is that server nodes or firewalls cannot distinguish the SYN packets of normal TCP connections from those of a SYN flood attack. Our method, FDFIX, relies on the use of monitoring and measurement techniques to evaluate the impact of denial-of-service (DoS) attacks. It uses flow-based measurements. Capturing flow information is very important for detecting DoS and other kinds of attacks. Flow monitoring allows detecting suspicious traffics, and in the next step can analyse attacking flows and the results can be used for defence methods. Our method provides required information for many mechanisms that use traffic measurement as its input.