a Review of Instructional Approaches

UIDB/00183/2020 UIDP/00183/2020 DL 57/2016/CP1453/CT0066 PTDC/FER-FIL/28278/2017Over the past 20 years, a broad and diverse research literature has emerged to address how students learn to argue through dialogue in educational contexts. However, the variety of approaches used to study this phenomenon makes it challenging to find coherence in what may otherwise seem to be disparate fields of study. In this integrative review, we propose looking at how learning to argue (LTA) has been operationalized thus far in educational research, focusing on how different scholars have framed and fostered argumentative dialogue, assessed its gains, and applied it in different learning contexts. In total, 143 studies from the broad literature on educational dialogue and argumentation were analysed, including all educational levels (from primary to university). The following patterns for studying how dialogue fosters LTA emerged: whole-class ‘low structure’ framing with a goal of dialogue, small-group ‘high structure’ framing with varied argumentative goals, and studies with one-to-one dialectic framing with a goal of persuasive deliberation. The affordances and limitations of these different instructional approaches to LTA research and practice are discussed. We conclude with a discussion of complementarity of the approaches that emerged from our analysis in terms of the pedagogical methods and conditions that promote productive and/or constructive classroom interactions.publishersversionepub_ahead_of_prin

The Effect of Task Instructions on Students' Use of Repetition in Argumentative Discourse

The reasoning belief of argumentum ad nauseam assumes that when someone repeats something often enough, he or she becomes more convincing. The present paper analyses the use of this strategy by seventh-grade students in an argumentation task. Sixty-five students (mean age: 12.2, SD = 0.4) from a public school in a mid-sized urban environment took part in the study. The students were asked to either argue to convince an opposing partner or argue to reach consensus with an opposing partner on three dilemmas that dealt with energy sources. Data were gathered according to a between-groups design that included one independent variable (argumentative goal: to convince vs. to reach consensus) and one dependent variable (the degree of argumentative repetitions). We predicted that in the condition to convince their partner, the students would use the repetition strategy more often in their attempts to be persuasive. Our findings show that the mean number of argumentative repetitions was significantly higher for the persuasion group for both of the most frequent argumentative structures (claim and claim data). The mean percentage of repeated claims for the persuasion condition was 86.2 vs. 69.0 for the consensus condition. For the claim data, the mean percentage for the persuasion group was 35.2 vs. 24.3 for the consensus group. Also, students in the persuasion group tended to repeat one idea many times rather than repeating many ideas a few times within the same argumentative structure. The results of our study support the hypothesis that the goal of the argumentative task mediates argumentative discourse and, more concretely, the rate of repetitions and the conceptual diversity of the statements. These differences in rates of repetition and conceptual diversity are related to the amount of learning produced by the instructional goal. We apply Mercer's idea that not all classroom argumentation tasks promote learning equally

Groundwater Flow and Elastoplastic Stress-Strain Model for Cohesive Soils with Application to Channel Bank Stability

A saturated-unsaturated groundwater flow and elastoplastic stress-strain finite element model was developed for simulating the mechanical behavior of rill and gully sized channel banks. The model coupled the two-dimensional saturated-unsaturated groundwater flow equation with a plane strain formulation of the virtual work equation. The constitutive relationship used the modified Cam clay yield function. The model included the effects of seepage force and variation in soil cohesive strength due to changes in water content and void ratio. A staggered solution procedure was used in which the groundwater equation was solved first to determine seepage force and soil cohesive force, and then the stress-strain equation was solved. Upon reaching the failure point, the elastoplastic constitutive relationship was replaced with a weak elastic relationship. The model was verified by comparing predictions with (1) one-dimensional analytic solutions for unsaturated flow, saturated flow, and elastic strain; (2) other numerical solutions using the modified Cam clay yield function; (3) triaxial tests; and (4) laboratory experiments. The laboratory experiments employed a specially designed cyclic soil compactor and plexiglass flume to form and compact channel banks. The channel banks were subjected to a rising and falling hydrograph. Model simulation included groundwater movement into the channel bank, strain in the x-direction, and the location of finite elements which reached ultimate strength. Failure surfaces were delineated by zones of high x-strain in conjunction with finite elements which reached ultimate strength. The model provided good insight into the failure mechanism for popout failure and a reasonable prediction of plane failure

Developement of real time diagnostics and feedback algorithms for JET in view of the next step

Real time control of many plasma parameters will be an essential aspect in the development of reliable high performance operation of Next Step Tokamaks. The main prerequisites for any feedback scheme are the precise real-time determination of the quantities to be controlled, requiring top quality and highly reliable diagnostics, and the availability of robust control algorithms. A new set of real time diagnostics was recently implemented on JET to prove the feasibility of determining, with high accuracy and time resolution, the most important plasma quantities. With regard to feedback algorithms, new model–based controllers were developed to allow a more robust control of several plasma parameters. Both diagnostics and algorithms were successfully used in several experiments, ranging from H-mode plasmas to configuration with ITBs. Since elaboration of computationally heavy measurements is often required, significant attention was devoted to non-algorithmic methods like Digital or Cellular Neural/Nonlinear Networks. The real time hardware and software adopted architectures are also described with particular attention to their relevance to ITER.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

Efficiency of Varying Sediment Traps under Experimental Conditions Simulating Tidal Inundations

Accelerated sea-level rise (SLR) is threatening tidal marshes worldwide. An important control of tidal marsh survival under accelerated SLR is sediment deposition. Therefore, factors affecting sediment deposition rates (SDRs) have been studied extensively using various types of sediment traps. The efficiency of various sediment traps has been compared in several studies, but most of these were conducted in shallow lakes or rivers. In contrast, the efficiency of different sediment traps in tidal marshes is unknown. Therefore, the aim of this study was to compare the trapping efficiency of four frequently used sediment traps, namely flat traps constructed of either tiles or floor mat and circular traps with and without a lid, under controlled experimental conditions simulating tidal inundations in a flume. The strong differences between circular sediment traps (high efficiency) and both flat-surface sediment trap methods (low efficiency) found in this study were remarkable. Additionally, further evidence was found for decreases in SDRs with increasing distance to the inflow of the flume (sediment source) and with decreasing suspended sediment concentration. These findings indicate that trap design has a large influence on sedimentation rate and that studies using different types of sediment traps are not directly comparable

Cost Analysis In A Multi-Mission Operations Environment

Spacecraft control centers have evolved from dedicated, single-mission or single missiontype support to multi-mission, service-oriented support for operating a variety of mission types. At the same time, available money for projects is shrinking and competition for new missions is increasing. These factors drive the need for an accurate and flexible model to support estimating service costs for new or extended missions; the cost model in turn drives the need for an accurate and efficient approach to service cost analysis. The National Aeronautics and Space Administration (NASA) Huntsville Operations Support Center (HOSC) at Marshall Space Flight Center (MSFC) provides operations services to a variety of customers around the world. HOSC customers range from launch vehicle test flights; to International Space Station (ISS) payloads; to small, short duration missions; and has included long duration flagship missions. The HOSC recently completed a detailed analysis of service costs as part of the development of a complete service cost model. The cost analysis process required the team to address a number of issues. One of the primary issues involves the difficulty of reverse engineering individual mission costs in a highly efficient multimission environment, along with a related issue of the value of detailed metrics or data to the cost model versus the cost of obtaining accurate data. Another concern is the difficulty of balancing costs between missions of different types and size and extrapolating costs to different mission types. The cost analysis also had to address issues relating to providing shared, cloud-like services in a government environment, and then assigning an uncertainty or risk factor to cost estimates that are based on current technology, but will be executed using future technology. Finally the cost analysis needed to consider how to validate the resulting cost models taking into account the non-homogeneous nature of the available cost data and the decreasing flight rate. This paper presents the issues encountered during the HOSC cost analysis process, and the associated lessons learned. These lessons can be used when planning for a new multi-mission operations center or in the transformation from a dedicated control center to multi-center operations, as an aid in defining processes that support future cost analysis and estimation. The lessons can also be used by mature serviceoriented, multi-mission control centers to streamline or refine their cost analysis process

Green tea polyphenols and Tai Chi for bone health: Designing a placebo-controlled randomized trial

BACKGROUND: Osteoporosis is a major health problem in postmenopausal women. Evidence suggests the importance of oxidative stress in bone metabolism and bone loss. Tea consumption may be beneficial to osteoporosis due to its antioxidant capability. However, lack of objective data characterizing tea consumption has hindered the precise evaluation of the association between tea ingestion and bone mineral density in previous questionnaire-based epidemiological studies. On the other hand, although published studies suggest that Tai Chi (TC) exercise can benefit bone health and may reduce oxidative stress, all studies were conducted using a relatively healthy older population, instead of a high-risk one such as osteopenic postmenopausal women. Therefore, this study was designed to test an intervention including green tea polyphenol (GTP) and TC exercise for feasibility, and to quantitatively assess their individual and interactive effects on postmenopausal women with osteopenia. METHODS/DESIGN: One hundred and forty postmenopausal women with osteopenia (defined as bone mineral density T-score at the spine and/or hip between 1 to 2.5 SD below the reference database) were randomly assigned to 4 treatment arms: (1) placebo group receiving 500 mg medicinal starch daily, (2) GTP group receiving 500 mg of GTP per day, (3) placebo+TC group receiving both placebo treatment and TC training (60-minute group exercise, 3 times per week), and (4) GTP+TC group receiving both GTP and TC training for 24 weeks. The outcome measures were bone formation biomarker (serum bone alkaline phosphatase), bone resorption biomarker (serum tartrate resistant acid phosphatase), and oxidative DNA damage biomarker (urinary 8-hydroxy-2'-deoxyguanosine). All outcome measures were determined at baseline, 4, 12, and 24 weeks. Urinary and serum GTP concentrations were also determined at baseline, 4, 12, and 24 weeks for bioavailability. Liver function was monitored monthly for safety. A model of repeated measurements with random effect error terms was applied. Traditional procedures such as ANCOVA, chi-squared analysis, and regression were used for comparisons. DISCUSSION: We present the rationale, design, and methodology of a placebo-controlled randomized trial to investigate a new complementary and alternative medicine strategy featuring a dietary supplement and a mind-body exercise for alleviating bone loss in osteopenic postmenopausal women. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT0062539

Multi-step self-guided pathways for shape-changing metamaterials

Multi-step pathways, constituted of a sequence of reconfigurations, are central to a wide variety of natural and man-made systems. Such pathways autonomously execute in self-guided processes such as protein folding and self-assembly, but require external control in macroscopic mechanical systems, provided by, e.g., actuators in robotics or manual folding in origami. Here we introduce shape-changing mechanical metamaterials, that exhibit self-guided multi-step pathways in response to global uniform compression. Their design combines strongly nonlinear mechanical elements with a multimodal architecture that allows for a sequence of topological reconfigurations, i.e., modifications of the topology caused by the formation of internal self-contacts. We realized such metamaterials by digital manufacturing, and show that the pathway and final configuration can be controlled by rational design of the nonlinear mechanical elements. We furthermore demonstrate that self-contacts suppress pathway errors. Finally, we demonstrate how hierarchical architectures allow to extend the number of distinct reconfiguration steps. Our work establishes general principles for designing mechanical pathways, opening new avenues for self-folding media, pluripotent materials, and pliable devices in, e.g., stretchable electronics and soft robotics.Comment: 16 pages, 3 main figures, 10 extended data figures. See https://youtu.be/8m1QfkMFL0I for an explanatory vide