Motivation,engagement, and performance across multiple virtual reality sessions and levels of immersion

This study investigated changes in learners' motivation, engagement, performance, and spatial reasoning over time and across different levels of virtual reality (VR) immersion. Undergraduate participants explored a virtual solar system via a moderately immersive or highly immersive VR platform over three sessions. In a third condition, participants initially learned with moderate immersion and transitioned to higher immersion after the second session. Following research on novelty effects, we explored whether subjective experiences and performance would decline over time (e.g., decreasing motivation or performance) as participants became familiar with the virtual environment and tools. However, we hypothesized that transitional immersion (i.e., switching from moderate to higher immersion) might lead to a renewed sense of novelty. Results suggested that both moderate and higher levels of immersion were motivating, engaging, and supportive of learning. In contrast to predictions based on novelty effects, these outcomes did not decline overall as learners gained familiarity with the systems. However, transitional immersion emerged as a promising and testable pedagogical approach for future VR education. All participants also showed gains in spatial reasoning.     

Visual methods for determining ambient illumination conditions when viewing medical images in mobile display devices

Abstract— The quality of the displayed image on mobile devices is affected by the varying ambient illumination conditions. Determining appropriate viewing conditions for particular visual tasks requires time and the appropriate instrumentation. To this end, the usefulness of more practical visual tests for use in clinical environments were explored. Experiments to determine the limitations of mobile displays in terms of the visibility of subtle targets for different background luminance and ambient illumination with two mobile devices were conducted. A noise‐embedded text detection task and a threshold estimation staircase technique for a range of illuminance between 1 and 80,000 lx encompassing conditions found in dark reading rooms, office spaces, and outdoor scenarios has been compared. It was found that the text detection method holds promise as a surrogate for more complicated tests in the framework of a clinically practical implementation.     

Phase Change Materials for Life Science Applications

Phase change materials (PCMs) are a class of thermo-responsive materials that can be utilized to trigger a phase transition which gives them thermal energy storage capacity. Any material with a high heat of fusion is referred to as a PCM that is able to provide cutting-edge thermal storage. PCMs are commercially used in many applications like textile industry, coating, and cold storage typically for heat control. These intriguing substances have recently been rediscovered and employed in a broad range of life science applications, including biological, human body, biomedical, pharmaceutical, food, and agricultural applications. Benefiting from the changes in physicochemical properties during the phase transition makes PCMs also functional for barcoding, detection, and storage. Paraffin wax and polyethylene glycol are the most commonly studied PCMs due to their low toxicity, biocompatibility, high thermal stability, high latent enthalpy, relatively wide transition temperature range, and ease of chemical modification. Current challenges in employing PCMs for life science applications include biosafety and/or engineering difficulties. The focus of this review article is on the life science applications, evaluation, and safety aspects of PCMs. Herein, the advances and the potential of employing PCMs as a versatile platform for various types of life science applications are highlighted.     

Highly-Sensitive Skin-Attachable Eye-Movement Sensor Using Flexible Nonhazardous Piezoelectric Thin Film

Accurate and continuous monitoring of eye movements using compact, low-power-consuming, and easily-wearable sensors is necessary in personal and public health and safety, selected medical diagnosis techniques (point-of-care diagnostics), and personal entertainment systems. In this study, a highly sensitive, noninvasive, and skin-attachable sensor made of a stable flexible piezoelectric thin film that is also free of hazardous elements to overcome the limitations of current computer-vision-based eye-tracking systems and piezoelectric strain sensors is developed. The sensor fabricated from single-crystalline III-N thin film by a layer-transfer technique is highly sensitive and can detect subtle movements of the eye. The flexible eye movement sensor converts the mechanical deformation (skin deflection by eye blinking and eyeball motion) with various frequencies and levels into electrical outputs. The sensor can detect abnormal eye flickering and conditions caused by fatigue and drowsiness, including overlong closure, hasty eye blinking, and half-closed eyes. The abnormal eyeball motions, which may be the sign of several brain-related diseases, can also be measured, as the sensor generates discernable output voltages from the direction of eyeball movements. This study provides a practical solution for continuous sensing of human eye blinking and eyeball motion as a critical part of personal healthcare, safety, and entertainment systems.     

气象计算网格模式预报系统的建立与优化*

为了在气象部门内跨地域共享使用MM5模式系统,基于建成的气象计算网格平台,成功地接入了MM5模式系统。根据用户预报需求,设计了参数化和业务运行方案,建立了华中区域MM5数值预报应用系统。完成模式系统部署运行后,通过使用网格平台的资源调度和工作流引擎等工具手段,优化了后处理运行流程。运行分析表明网格平台上MM5模式系统的运行效率显著提高。     

实用电动推杆

电动推杆是一种位移执行机构,也是一种位置控制机构.可从结构和原理上介绍了一种新型电动推杆,并进行了试验.     

Single cell trapping in larger microwells capable of supporting cell spreading and proliferation

Conventional cell trapping methods using microwells with small dimensions (10–20 μm) are useful for examining the instantaneous cell response to reagents; however, such wells have insufficient space for longer duration screening tests that require observation of cell attachment and division. Here we describe a flow method that enables single cell trapping in microwells with dimensions of 50 μm, a size sufficient to allow attachment and division of captured cells. Among various geometries tested, triangular microwells were found to be most efficient for single cell trapping while providing ample space for cells to grow and spread. An important trapping mechanism is the formation of fluid streamlines inside, rather than over, the microwells. A strong flow recirculation occurs in the triangular microwell so that it efficiently catches cells. Once a cell is captured, the cell presence in the microwell changes the flow pattern, thereby preventing trapping of other cells. About 62% of microwells were filled with single cells after a 20 min loading procedure. Human prostate cancer cells (PC3) were used for validation of our system.     

Purification of a droplet using negative dielectrophoresis traps in digital microfluidics

The development of techniques for manipulating particles and integrating them into the digital microfluidic (DMF) devices has been the subject of several studies in recent years. This paper presents a dielectrophoretic-based method that uses triangular traps to manipulate particles and purify a droplet in DMF platforms. Numerical and experimental studies are conducted to show the effectiveness of the proposed trap geometry which is also compatible with the other operators in the DMF platform. The triangular trap geometry is used to move the polystyrene particles to one side of the trap using negative dielectrophoresis (nDEP). The droplet is then split into two smaller droplets with very low and high concentrations of particles using the electrowetting on dielectric technique. The average velocity of the particles (as they move along the trap) as a function of the vertex angle of the triangular trap and the gap between the top and bottom plate is examined. It is observed that the vertex angle of the trap plays more important role on the motion of the particles than the gap. Thus, to enhance the motion of the particles and minimize the effect of splitting on the purification process, the vertex angle and the slope of the side arms of the triangular trap are modified based on the results of the numerical model simulating the dielectrophoretic force on the particle. The enhanced geometry is fabricated and tested experimentally to show the effectiveness and ease-of-use of the proposed technique in purifying (or concentrating) a droplet in DMF. The results show that using the proposed nDEP electrode geometry purification (or concentration) can be performed with the efficiency of 90 %.     

Thermal behavior and electrical conductivity of ethylene vinyl acetate copolymer/expanded graphite nanocomposites: Effects of nanofiller size and loading

Nanocomposites based on ethylene‐vinyl acetate (EVA) copolymer and expanded graphite (EG) were prepared using direct and two‐step melt‐mixing processes. The effect of elongational flow on the dispersion of EG nanoparticles in the polymeric matrix was investigated by thermal analysis and electrical conductivity measurements. Two types of EG having different aspect ratio were applied to prepare the nanocomposites. The nanocomposites containing higher aspect ratio nanofiller have shown higher values of transition temperature (Tg) and a stronger reinforcing effect of EG. The evaluation of EVA crystallization behavior has clarified that both the EG loading and particle size have noticeably influenced the crystallization characteristics of EVA. The restrictions imposed by nanoparticles on molecular motion and, correspondingly, the crystal growth stage have been the most notable effect of EG nanopartciles on the EVA crystallization behavior. Moreover, the presence of EG nanofiller has intensified the formation of a second‐type of EVA crystals during long annealing time. Furthermore, chemically crosslinking of EVA chains has led to the formation of smaller crystals with more uniform size. J. VINYL ADDIT. TECHNOL., 22:51–60, 2016. © 2014 Society of Plastics Engineers