2,038 research outputs found
Moving Toward Blended Learning: A Multiple Case Design Based Research Study In Higher Education
The purpose of this multiple case design-based research study was to determine what elements were needed to assist two higher education instructors inexperienced in designing and teaching a blended learning course to successfully create and implement it, to document the instructors’ perceptions about their first experience of teaching a blended learning course, and to reveal how this blended learning course influenced student satisfaction. The goal of the study was to iteratively design, develop, implement, evaluate and redesign a desired blended learning course based on constructivist design theory, cognitive learning theory, and ARCS motivational design theory over the three iterative phases.
This design-based research approach used a mixed study of quantitative and qualitative research methods including student surveys, instructor interviews, learning environment and observations. Quantitative data in terms of determining any change in the level of students’ motivation between the beginning of the semester and the end of the semester, and students’ motivational attitude toward the use of instructional activities and tools at the fifth and tenth week of the semester was collected. Multiple choice comprehensive pretest and posttest surveys were given to students to detect changes in their motivation level, and a multiple choice comprehensive survey was given to students to detect their motivational attitude. Qualitative data in terms of identifying the need of appropriate technological processes and resources to create a desired blended learning course, enhancing the effectiveness and efficiency of the blended learning course, and revealing instructor perceptions about teaching a blended learning course was collected over the three iterative designed intervention phases. Instructor perceptions were captured through in-depth interviews, and the strengths and weaknesses of the blended learning environment were ascertained through observations.
The results of this study demonstrated Blackboard Learn (Learning Management System) and Google Documents were two beneficial learning resources to create a desired blended learning environment. The design and implementation of these learning resources enabled the instructors to shift from a passive teaching style to an active teaching style. Students became active and interactive learners through the adoption of active learning approaches and transactional collaborative learning approaches in the designed blended learning environments. Through the process of three iterative design cycles, the blended learning environments were modified to optimize the efficiency and effectiveness of learning activities and maximize the quality of learning and teaching experiences. The results also revealed that the instructors’ overall perception was positive toward taking part in combining online and face-to-face learning and they were satisfied with teaching a blended learning course. Lastly, findings from the paired t-test completed in SPSS which compared the students’ motivation level in the beginning of the semester and the end of the semester were not statistically significant in both cases
Experimental Evaluation of Mechanical Properties and Fracture Behavior of Carbon Fiber Reinforced High Strength Concrete
Concrete without reinforcement is brittle which is intensified in high strength concrete. Fibers have been utilized to improve the tensile and bending performance of concrete. Fibers primarily control the propagation of cracks and limit the crack width. Carbon fiber reinforced concretes are reliable structural materials with superior performance characteristics compared to conventional concrete. The addition of carbon fiber in concrete has been found to improve several properties, primarily cracking resistance, ductility and fatigue life. This paper reports a study on the mechanical and fracture properties of high strength concrete reinforced with different volume fractions of carbon fiber. Four different volume fractions between the range of 0.25% and 1.00% were chosen. Carbon fiber improved the compressive strength, load bearing capacity, fracture energy and toughness of concrete. Fiber volume fraction was more prominent factor in this regard. Fracture parameters showed better performance beyond 0.50% fiber inclusion
Cylindrically Symmetric Vacuum Solutions in Higher Dimensional Brans-Dicke Theory
Higher dimensional, static, cylindrically symmetric vacuum solutions with and
without a cosmological constant in the Brans-Dicke theory are presented. We
show that, for a negative cosmological constant and for specific values of the
parameters, a particular subclass of these solutions include higher dimensional
topological black hole-type solutions with a flat horizon topology. We briefly
extend our discussion to stationary vacuum and vacuum solutions.Comment: V3: Published Versio
The dynamical mass and evolutionary status of the type-II Cepheid in the eclipsing binary system OGLE-LMC-T2CEP-211 with a double-ring disk
We present the analysis of a peculiar W~Virginis (pWVir) type-II Cepheid,
OGLE-LMC-T2CEP-211 (), in a double-lined binary system
(), which shed light on virtually unknown evolutionary status
and structure of pWVir stars. The dynamical mass of the Cepheid (first ever for
a type-II Cepheid) is and the radius
. The companion is a massive ()
main-sequence star obscured by a disk. Such configuration suggests a mass
transfer in the system history. We found that originally the system
() was composed of and stars, with
the current Cepheid being more massive. The system age is now 200 My,
and the Cepheid is almost completely stripped of hydrogen, with helium mass of
of the total mass. It finished transferring the mass 2.5 My ago
and is evolving towards lower temperatures passing through the instability
strip. Comparison with observations indicate a reasonable
mass loss from the Cepheid. The companion is
most probably a Be main-sequence star with and .
Our results yield a good agreement with a pulsation theory model for a
hydrogen-deficient pulsator, confirming the described evolutionary scenario. We
detected a two-ring disk () and a shell
() around the companion, that is probably a
combination of the matter from the past mass transfer, the mass being lost by
the Cepheid due to wind and pulsations, and a decretion disk around a rapidly
rotating secondary. Our study together with observational properties of pWVir
stars suggests that their majority are products of a similar binary evolution
interaction.Comment: 21 pages, 14 figures, 6 tables, accepted for publication in Ap
Traction force microscopy with optimized regularization and automated Bayesian parameter selection for comparing cells
Adherent cells exert traction forces on to their environment, which allows
them to migrate, to maintain tissue integrity, and to form complex
multicellular structures. This traction can be measured in a perturbation-free
manner with traction force microscopy (TFM). In TFM, traction is usually
calculated via the solution of a linear system, which is complicated by
undersampled input data, acquisition noise, and large condition numbers for
some methods. Therefore, standard TFM algorithms either employ data filtering
or regularization. However, these approaches require a manual selection of
filter- or regularization parameters and consequently exhibit a substantial
degree of subjectiveness. This shortcoming is particularly serious when cells
in different conditions are to be compared because optimal noise suppression
needs to be adapted for every situation, which invariably results in systematic
errors. Here, we systematically test the performance of new methods from
computer vision and Bayesian inference for solving the inverse problem in TFM.
We compare two classical schemes, L1- and L2-regularization, with three
previously untested schemes, namely Elastic Net regularization, Proximal
Gradient Lasso, and Proximal Gradient Elastic Net. Overall, we find that
Elastic Net regularization, which combines L1 and L2 regularization,
outperforms all other methods with regard to accuracy of traction
reconstruction. Next, we develop two methods, Bayesian L2 regularization and
Advanced Bayesian L2 regularization, for automatic, optimal L2 regularization.
Using artificial data and experimental data, we show that these methods enable
robust reconstruction of traction without requiring a difficult selection of
regularization parameters specifically for each data set. Thus, Bayesian
methods can mitigate the considerable uncertainty inherent in comparing
cellular traction forces
Care levels for fetal therapy centers
Fetal therapies undertaken to improve fetal outcome or to optimize transition to neonate life often entail some level of maternal, fetal, or neonatal risk. A fetal therapy center needs access to resources to carry out such therapies and to manage maternal, fetal, and neonatal complications that might arise, either related to the therapy per se or as part of the underlying fetal or maternal condition. Accordingly, a fetal therapy center requires a dedicated operational infrastructure and necessary resources to allow for appropriate oversight and monitoring of clinical performance and to facilitate multidisciplinary collaboration between the relevant specialties. Three care levels for fetal therapy centers are proposed to match the anticipated care complexity, with appropriate resources to achieve an optimal outcome at an institutional and regional level. A level I fetal therapy center should be capable of offering fetal interventions that may be associated with obstetric risks of preterm birth or membrane rupture but that would be very unlikely to require maternal medical subspecialty or intensive care, with neonatal risks not exceeding those of moderate prematurity. A level II center should have the incremental capacity to provide maternal intensive care and to manage extreme neonatal prematurity. A level III therapy center should offer the full range of fetal interventions (including open fetal surgery) and be able manage any of the associated maternal complications and comorbidities, as well as have access to neonatal and pediatric surgical intervention including indicated surgery for neonates with congenital anomalies
Effect of Prewetted Pumice Aggregate Addition on Concrete Properties under Different Curing Conditions
This study researches the effects of different curing conditions on the properties of high strength concrete containing presoaked pumice aggregate (PA). Fine normal weight aggregate is substituted by an equal volume of 1h and 24h presoaked PA at 50% and 100% fractions and a total of five concrete mixtures were prepared. After kept in water, air and hot weather, the performance of concretes were evaluated by determining their physical and mechanical properties at 28 days. Hot weather was found to be the most detrimental condition where the highest strength drops were observed. Frost resistance of concretes was improved with the use of presoaked PA at 50% replacement ratio. The use of presoaked PA also decreased the shrinkage values of concrete specimens. The results showed that the use of presoaked PA in high strength concrete at 50% replacement ratio could contribute to concrete properties when exposed to inadequate curing conditions
Low/Zero-Carbon Buildings for a Sustainable Future
Fossil fuel-based energy consumption is still dominant in the world today, and there is a consensus on the limited reserves of these energy resources. Therefore, there is a strong stimulation into clean energy technologies to narrow the gap between fossil fuels and renewables. In this respect, several commitments and codes are proposed and adopted for a low energy-consuming world and for desirable environmental conditions. Sectoral energy consumption analyses clearly indicate that buildings are of vital importance in terms of energy consumption figures. From this point of view, buildings have a great potential for decisive and urgent reduction of energy consumption levels and thus greenhouse gas (GHG) emissions. Among the available retrofit solutions, greenery systems (GSs) stand for a reliable, cost-effective and eco-friendly method for remarkablemitigation of energy consumed in buildings. Through the works comparing the thermal regulation performance of uninsulated and green roofs, it is observed that the GS provides 20°C lower surface temperature in operation. Similar to green roofs, vertical greenery systems (VGSs) also reduce energy demand to approximately 25% as a consequence of wind blockage effects in winter. Therefore, within the scope of this chapter, GSs are evaluated for a reliable and effective retrofit solution toward low/zero carbon buildings (L/ZCBs)
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