Origin of Second Harmonic Generation from individual Silicon Nanowires

We investigate Second Harmonic Generation from individual silicon nanowires and study the influence of resonant optical modes on the far-field nonlinear emission. We find that the polarization of the Second Harmonic has a size-dependent behavior and explain this phenomenon by a combination of different surface and bulk nonlinear susceptibility contributions. We show that the Second Harmonic Generation has an entirely different origin, depending on whether the incident illumination is polarized parallel or perpendicularly to the nanowire axis. The results open perspectives for further geometry-based studies on the origin of Second Harmonic Generation in nanostructures of high-index centrosymmetric semiconductors.Comment: 7 Pages, 4 Figures + 3 Pages, 6 Figures in Appendi

Analysis of supermarket CO2 refrigeration cycles equipped with multi-ejectors

This thesis presents an analysis of operating conditions in a refrigeration system located in supermarket Rema 1000 Prinsensgata, Trondheim (Norway). The main emphasis is put on a problem with oversized gas cooler, which occurs during low ambient temperatures (in winter), and is a root of unstable operation of the whole system. Furthermore, possible solutions to this problem are depicted, among them are: division and cut-down of gas cooler s surface, application of bypassing valve to the gas cooler, triggering fresh air inside supermarket s airhandling-unit (AHU), and utilization of air shutters to the gas cooler. Subsequently, a simulation in a heat exchanger modelling computer program hXSIM (the Heat Exchanger Simulator) of the gas cooler split and increased subcooling is depicted. Lastly, the thesis portrays practical changes which were implemented in the system: exploitation of heat recovery system by snowmelting- unit (street-heating-unit), use of a shut-off valve to decrease the capacity of the gas cooler, implementation of a new controller for the ejectors, reprogramming fans, and also connection of the data acquisition system with energy meters mounted in supermarket s machine room

The perceived effects of faculty presence vs. absence on small-group learning and group dynamics: a quasi-experimental study

BACKGROUND: Medical education increasingly relies on small-group learning. Small group learning provides more active learning, better retention, higher satisfaction, and facilitates development of problem-solving and team-working abilities. However, less is known about student experience and preference for different small groups teaching models. We evaluated group educational dynamics and group learning process in medical school clerkship small group case-based settings, with a faculty member present versus absent. METHODS: Students completed surveys after cases when the faculty was present (“in”) or absent (“out”) for the bulk of the discussion. 228 paired surveys (114 pairs) were available for paired analysis, assessing group dynamics, group learning process, student preference, and participation through self-report and self-rating of group behaviors tied to learning and discussion quality. RESULTS: Ratings of group dynamics and group learning process were significantly higher with the faculty absent vs. present (p range <0.001 to 0.015). Students also reported higher levels of participation when the faculty member was absent (p = 0.03). Students were more likely to express a preference for having the faculty member present after “in” case vs. “out” case discussions. (p < 0.001). There was no difference in reported success of the case discussion after “in” vs. “out” cases (p = 0.67). CONCLUSIONS: Student groups without faculty present reported better group dynamics, group learning processes, and participation with faculty absent. Students reported that they feel somewhat dependent on faculty, especially when the faculty is present, though there was no significant difference in students reporting that they obtained the most they could from the discussion of the case after both “in” and “out” cases

Communicative competence of a child with cerebral palsy and mild intellectual disability

In the article, the communicative competence of a 12 year old girl with cerebral palsy and mild intellectual disability was characterised. These developmental disorders exert a significant impact on child’s skills in the field of speech expression and perception. Moreover, they lead to speech disorders: oligophasia and dysarthria. The case study method was used to conduct the research. In the first part of this article the authors described two issues: cerebral palsy and intellectual disability. They indicated the causes, as well as the most common symptoms of these developmental disorders. In the next part the authors provided an extensive description of various diagnostic tests. They enabled the researchers to explore, among others, speech expression and perception, as well as phonematic hearing. The results of these different tests were thoroughly analysed. Consequently, it has been proved that the level of child’s linguistic and communication skills corresponds to the results achieved by children with similar deficits and disorders

AN EMPIRICAL STUDY OF STRATEGIES FOR UNDERSTANDING QUANTITATIVE DECISION MODELS

Demos is a modeling environment designed to help a co-operating team design, analyze, critique and refine quantitative models for policy research. Earlier research found that readers of Demos models tended to become disoriented while exploring models online. In response we have designed and implemented a graphical interface to Demos named Demaps. Demaps displays diagrams of the model structure, both dependence networks and abstraction hierarchies, to provide graphic context and direct manipulation style of interaction. We describe a study of the use of Demaps to understand and compare multiple versions of models. The study employs verbal protocol analysis to evaluate the design of Demaps and to discover expert strategies for model understanding and criticism. Subjects were able to learn to use Demaps effectively in about an hour to review and compare policy models and perform sensitivity analyses. The study describes two strategies used in reading models and suggests the desirability of additional facilities for recording model critiques and accessing detailed background information on models. *We gratefully acknowledge the contributions of many people, including Jill Larkin, Jim Morris, Granger Morgan, Andrew Appel. and our subjects. This work was supported by the Information Technology Center and the National Science Foundation under grant IST-8316890

Evaluation of a web-based asthma self-management system: a randomised controlled pilot trial

Background Asthma is the most common chronic condition of childhood and disproportionately affects inner-city minority children. Low rates of asthma preventer medication adherence is a major contributor to poor asthma control in these patients. Web-based methods have potential to improve patient knowledge and medication adherence by providing interactive patient education, monitoring of symptoms and medication use, and by facilitation of communication and teamwork among patients and health care providers. Few studies have evaluated web-based asthma support environments using all of these potentially beneficial interventions. The multidimensional website created for this study, BostonBreathes, was designed to intervene on multiple levels, and was evaluated in a pilot trial. Methods An interactive, engaging website for children with asthma was developed to promote adherence to asthma medications, provide a platform for teamwork between caregivers and patients, and to provide primary care providers with up-to-date symptom information and data on medication use. Fifty-eight (58) children primarily from inner city Boston with persistent-level asthma were randomised to either usual care or use of BostonBreathes. Subjects completed asthma education activities, and reported their symptoms and medication use. Primary care providers used a separate interface to monitor their patients’ website use, their reported symptoms and medication use, and were able to communicate online via a discussion board with their patients and with an asthma specialist. Results After 6-months, reported wheezing improved significantly in both intervention and control groups, and there were significant improvements in the intervention group only in night-time awakening and parental loss of sleep, but there were no significant differences between intervention and control groups in these measures. Emergency room or acute visits to a physician for asthma did not significantly change in either group. Among the subgroup of subjects with low controller medication adherence at baseline, adherence improved significantly only in the intervention group. Knowledge of the purpose of controller medicine increased significantly in the intervention group, a statistically significant improvement over the control group. Conclusions This pilot study suggests that a multidimensional web-based educational, monitoring, and communication platform may have positive influences on pediatric patients’ asthma-related knowledge and use of asthma preventer medications