218 research outputs found
Identifying Non-Sustainable Courses of Action: A Prerequisite for Decision-Making in Education for Sustainable Development
No full textStudents are faced with a multitude of decisions as consumers and in societal debates. Because of the scarcity of resources, the destruction of ecosystems and social injustice in a globalized world, it is vital that students are able to identify non-sustainable courses of action when involved in decision-making. The application of decision-making strategies is one approach to enhancing the quality of decisions. Options that do not meet ecological, social or economic standards should be excluded using non-compensatory strategies whereas other tasks may require a complete trade-off of all the evidence, following a compensatory approach. To enhance decision-making competence, a computer-based intervention study was conducted that focused on the use of decision-making strategies. While the results of the summative evaluation are reported by Gresch et al. (International Journal of Science Education, 2011), in-depth analyses of process-related data collected during the information processing are presented in this paper to reveal insights into the mechanisms of the intervention. The quality of high school students' (n = 120) metadecision skills when selecting a decision-making strategy was investigated using qualitative content analyses combined with inferential statistics. The results reveal that the students offered elaborate reflections on the sustainability of options. However, the characteristics that were declared non-sustainable differed among the students because societal norms and personal values were intertwined. One implication for education for sustainable development is that students are capable of reflecting on decision-making tasks and on corresponding favorable decision-making strategies at a metadecision level. From these results, we offer suggestions for improving learning environments and constructing test instruments for decision-making competence
Quantum walks of kicked Bose-Einstein condensates
No full textWe analytically investigate the recently proposed and implemented discrete-time quantum walk based on kicked ultra-cold atoms. We show how the internal level structure of the kicked atoms leads to the emergence of a relative lightshift phase immediately relevant for the experimental realization. Analytical solutions are provided for the momentum distribution for both the case of quantum resonance and the near-resonant quasimomenta
Training in Decision-making Strategies: An approach to enhance students’ competence to deal with socio-scientific issues
No full textDealing with socio-scientific issues in science classes enables students to participate productively in controversial discussions concerning ethical topics, such as sustainable development. In this respect, well-structured decision-making processes are essential for elaborate reasoning. To foster decision-making competence, a computer-based programme was developed that trains secondary school students (grades 11-13) in decision-making strategies. The main research question is: does training students to use these strategies foster decision-making competence? In addition, the influence of meta-decision aids was examined. Students conducted a task analysis to select an appropriate strategy prior to the decision-making process. Hence, the second research question is: does combining decision-making training with a task analysis enhance decision-making competence at a higher rate? To answer these questions, 386 students were tested in a pre-post-follow-up control-group design that included two training groups (decision-making strategies/decision-making strategies combined with a task analysis) and a control group (decision-making with additional ecological information instead of strategic training). An open-ended questionnaire was used to assess decision-making competence in situations related to sustainable development. The decision-making training led to a significant improvement in the post-test and the follow-up, which was administered three months after the training. Long-term effects on the quality of the students' decisions were evident for both training groups. Gains in competence when reflecting upon the decision-making processes of others were found, to a lesser extent, in the training group that received the additional meta-decision training. In conclusion, training in decision-making strategies is a promising approach to deal with socio-scientific issues related to sustainable development
Enhancing Decision-Making in STSE Education by Inducing Reflection and Self-Regulated Learning
No full textThoughtful decision-making to resolve socioscientific issues is central to science, technology, society, and environment (STSE) education. One approach for attaining this goal involves fostering students' decision-making processes. Thus, the present study explores whether the application of decision-making strategies, combined with reflections on the decision-making processes of others, enhances decision-making competence. In addition, this study examines whether this process is supported by elements of self-regulated learning, i.e., self-reflection regarding one's own performance and the setting of goals for subsequent tasks. A computer-based training program which involves the resolution of socioscientific issues related to sustainable development was developed in two versions: with and without elements of self-regulated learning. Its effects on decision-making competence were analyzed using a pre test-post test follow-up control-group design (N = 242 high school students). Decision-making competence was assessed using an open-ended questionnaire that focused on three facets: consideration of advantages and disadvantages, metadecision aspects, and reflection on the decision-making processes of others. The findings suggest that students in both training groups incorporated aspects of metadecision into their statements more often than students in the control group. Furthermore, both training groups were more successful in reflecting on the decision-making processes of others. The students who received additional training in self-regulated learning showed greater benefits in terms of metadecision aspects and reflection, and these effects remained significant two months later. Overall, our findings demonstrate that the application of decision-making strategies, combined with reflections on the decision-making process and elements of self-regulated learning, is a fruitful approach in STSE education.German Research Foundation (Deutsche Forschungsgemeinschaft
Experimental realization of a momentum-space quantum walk
No full textWe report on a discrete-time quantum walk that uses the momentum of ultra-cold rubidium-87 atoms as the walk space and two internal atomic states as the coin degree of freedom. Each step of the walk consists of a coin toss (a microwave pulse) followed by a unitary shift operator (a resonant ratchet pulse). We carry out a comprehensive experimental study on the effects of various parameters, including the strength of the shift operation, coin parameters, noise, and initialization of the system on the behavior of the walk. The walk dynamics can be well controlled in our experiment; potential applications include atom interferometry and engineering asymmetric walks
Light-shift-induced behaviors observed in momentum-space quantum walks
No full textOver the last decade there have been many advances in studies of quantum walks (QWs) including a momentum-space QW recently realized in our spinor Bose-Einstein condensate system. This QW possessed behaviors that generally agreed with theoretical predictions; however, it also showed momentum distributions that were not adequately explained by the theory. We present a theoretical model which proves that the coherent dynamics of the spinor condensate is sufficient to explain the experimental data without invoking the presence of a thermal cloud of atoms as in the original theory. Our numerical findings are supported by an analytical prediction for the momentum distributions in the limit of zero-temperature condensates. This current model provides more complete explanations to the momentum-space QWs that can be applied to study quantum search algorithms and topological phases in Floquet-driven systems
Quartz-enhanced photoacoustic spectroscopy employing a Vernier-effect distributed feedback-quantum cascade laser for multiple analytes detection
No full textHere we report on the multi-gas detection of carbon monoxide (CO), nitrous oxide (N2O), carbon dioxide (CO2), and water vapor (H2O) by using a quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor exploiting a Vernier effect-based quantum cascade laser as excitation source. The device emission wavelengths ranged from 2100 cm(-1) to 2250 cm(-1). The achieved minimum detection limits were 6 ppb, 7 ppb, and 71 ppm for CO, N2O, and CO2, respectively, at 100 ms of integration time. Finally, QEPAS sensor performances were tested retrieving the concentrations of the target gases within laboratory air
Influence of InAs, AlAs δ-layers on the optical electronic and thermal characteristics of strain-compensated GaInAs/AlInAs quantum cascade lasers
No full textWe extracted the electronic temperatures, the thermal resistance RL=11.5 K/W, the
cross-plane thermal conductivity k=2.0±0.1 W/ Km, and the thermal boundary resistance
TBR=4.1–9.310−10 K/W m2 in strain-compensated Ga0.609In0.391As/AlIn0.546As0.454
quantum-cascade lasers operating at 4.78 m in continuous wave up to 15 °C and in pulsed mode
up to 40 °C. Submonolayer thick InAs and AlAs layers are included in the active region to
increase the conduction band discontinuity. We found that potential interface broadening caused by
the insertion of these layers allows for a 43% improvement of the thermal conductivity with
respect to conventional lattice-matched GaInAs/AlInAs heterostructures
Quantum Walk in Momentum Space with a Bose-Einstein Condensate
No full textWe present a discrete-time, one-dimensional quantum walk based on the entanglement between the momentum of ultracold rubidium atoms (the walk space) and two internal atomic states (the "coin" degree of freedom). Our scheme is highly flexible and can provide a platform for a wide range of applications such as quantum search algorithms, the observation of topological phases, and the realization of walks with higher dimensionality. Along with the investigation of the quantum-to-classical transition, we demonstrate the distinctive features of a quantum walk and contrast them to those of its classical counterpart. Also, by manipulating either the walk or coin operator, we show how the walk dynamics can be steered or even reversed
Mid infrared quantum cascade laser operating in pure amplitude modulation for background-free trace gas spectroscopy
No full textWe present a single mode multi-section quantum cascade laser source composed of three different sections: Master oscillator, gain and phase section. Non-uniform pumping of the QCL's gain reveals that the various laser sections are strongly coupled. Simulations of the electronic and optical properties of the laser (based on the density matrix and scattering matrix formalisms, respectively) were performed and a good agreement with measurements is obtained. In particular, a pure modulation of the laser output power can be achieved. This capability of the device is applied in tunable-laser spectroscopy of N2O where background-free quartz enhanced photo acoustic spectral scans with nearly perfect Voigt line shapes for the selected absorption line are obtained
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