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71.
In this study, the effectiveness of an oral history assignment was assessed in a traditional gerontology class versus a distance education (DE) gerontology class. Attitudes toward older adults and the aging process were measured before and after students in the traditional (n = 29) and DE (n = 16) setting completed an oral history assignment. Scores were evaluated at posttest for differences between groups. The assignment positively influenced students' attitude toward older adults in both classes. Results indicate that this assignment was as effective in the DE setting as in the traditional setting. Findings suggest that oral history is an effective teaching assignment in a DE gerontology class.  相似文献   
72.
The authors examined whether motivational goals influenced the participation and performance of low-achieving students during collaborative problem solving with a high-achieving partner. Thirty-five pairs of 4th- and 5th-grade students were randomly assigned a set of instructions designed to induce students to adopt a learning goal or a performance goal. The following day, the students were individually given a posttest on problems similar to those worked on collaboratively. The low-achieving students given learning-goal instructions performed better on the posttest problems and perceived their partner's competence as more similar to their own than did the low-achieving students given performance-goal instructions. No differences in overall amount or level of low achievers' participation during collaborative problem solving were observed. Implications of the findings for the use of peer learning in heterogeneous classrooms are discussed.  相似文献   
73.
Zusammenfassung.   Für ein vollst?ndig computergestütztes Planungssystem zum Zwecke der kieferchirurgischen Operationsplanung ist die Bereitstellung von virtuellen Werkzeugen für den Chirurgen eine grundlegende Voraussetzung. Ausgehend von den Volumendaten mit Sch?del- und Kieferknochen des Patienten erm?glicht ein einfaches Interface unter Verwendung einer geeigneten Visualisierung und haptischer Eingabeger?te die interaktive Definition und Manipulation einzelner virtueller Knochensegmente. Wir haben moderne kraftrückgekoppelte Ger?te aus dem Niedrigpreisbereich eingebunden und auf ihre F?higkeit untersucht, das dreidimensionale Verst?ndnis im Planungsproze?durch Anlehnung an die Vorg?nge bei der chirurgischen Prozedur zu erh?hen. Durch diese Eingabeger?te ist es m?glich, die Knochensegmentierung für eine Osteotomie des Unterkiefers intuitiver und schneller durchzuführen. Die definierten Teilvolumina ergeben zusammen mit ihrer r?umlichen Neuanordnung auf Grundlage einer kephalometrischen Analyse einen Operationsplan. Nach erfolgter Planung werden die Planungsergebnisse in den Operationssaal übertragen. Die intraoperativen Techniken beinhalten die Visualisierung der Planungsergebnisse, die Steuerung der Anwendung über Sprache und die Bestimmung der Patientenposition mittels eines elektromagnetischen 3D-Trackingsystems. Eingegangen am 27. April 2000 / Angenommen am 21. Februar 2001  相似文献   
74.
Performing and learning motor skills has been shown to be enhanced if the performer adopts an external relative to internal focus (or no focus) of attention (Wulf 2007). The present study examined the generalizability of this effect to top-level performers (balance acrobats). Participants performed a balance task (standing on an inflated rubber dish) under each of three attentional focus conditions: (a) external focus (i.e., minimize movements of the disk), (b) internal focus (i.e., minimize movements of the feet), and (c) control conditions (no focus instructions). While there were no differences between conditions in the amount of postural sway, the frequency of movement adjustments was higher in the control condition, relative to both external and internal focus conditions. This suggests that movement automaticity and postural stability were greatest when the balance experts were free to adopt their "normal" focus of attention. The finding implies that there may be a limit to the performance-enhancing effects of external focus instructions for top-level performers. The findings are discussed in terms of action control levels and possible changes in the optimal attentional focus with the performer's level of expertise.  相似文献   
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76.
An archaeological excavation has been carried out at Pisa (Italy), unearthing an ancient metallurgical workshop. Since archaeological burnt materials provide important records of direction and intensity of the Earth's magnetic field in the past and they can be used to better improve geomagnetic secular variation curves (SVCs), an archaeomagnetic study has been performed. This small copper-alloy furnace presents a circular concave shape covered with a thin layer of mortar, with some traces of heated clay surrounding the feature that confirms the high temperature reached inside it. Archaeological context dating points to the last firing of the furnace between the last quarter of the 13th century and the first quarter of 14th century AD, when then the metallurgical workshop was transformed in a warehouse. Archaeomagnetic sampling has been performed using the modified Thellier method, by collecting several, large and independently oriented aliquots of heated clay, forming the bottom part of the circular wall of the structure. Laboratory treatments have been conducted at the IGG-CNR ARCHEO_LAB (Pisa, Italy) and at St. Maur Palaeomagnetic laboratory (Paris, France). Analytical measurements of the thermo-remanent magnetization index acquired from the samples have been performed using a large cell induction magnetometer for large samples, and the characteristic remanent magnetization (ChRM) has been successfully isolated after an alternate field demagnetization cleaning procedure for each sample. The final mean archaeomagnetic direction has been calculated at sampling site (D = 6.9°; I = 52.8°; N = 9; k = 305; α95 = 2.6°) following the Fisher Statistics, and it exhibits a perfect agreement with some coeval already published directions obtained from Mt. Arso lava flows, these latter being an important anchor point in the preliminary Italian secular variation curve. Comparison with the preliminary Italian SVC, the French SVC and the SCHA.DIF.3K archaeomagnetic regional model have permitted to define an archaeomagnetic absolute age confirming the conventional archaeological age, underlining the importance of this result into the Italian archaeomagnetic data set.  相似文献   
77.
78.
In this paper, two methodological perspectives are used to elaborate on the value of cognitive load theory (CLT) as a scientific theory. According to the more traditional critical rationalism of Karl Popper, CLT cannot be considered a scientific theory because some of its fundamental assumptions cannot be tested empirically and are thus not falsifiable. According to the structuralist view of theories introduced by Joseph D. Sneed, a theory may be considered scientific even if it comprises nontestable fundamental assumptions. Rather, the scientific value of a theory results from the holistic empirical content of the overall theory net built around fundamental assumptions and from the successful applications of this theory net to explain and predict empirical findings. This latter view is helpful to explicate some implicit methodological assumptions of CLT research and to avoid the potential circularity of CLT’s fundamental assumptions. Additionally, the structuralist view of theories can be directly used to derive a research agenda for the future development of CLT.  相似文献   
79.
The problem of position tracking of a mini drone subject to wind perturbations is investigated. The solution is based on a detailed unmanned aerial vehicle (UAV) model, with aerodynamic coefficients and external disturbance components, which is introduced in order to better represent the impact of the wind field. Then, upper bounds of wind-induced disturbances are characterized, which allow a sliding mode control (SMC) technique to be applied with guaranteed convergence properties. The peculiarity of the considered case is that the disturbance upper bounds depend on the control amplitude itself (i.e. the system is nonlinear in control), which leads to a new procedure for the control tuning presented in the paper. The last part of the paper is dedicated to the analysis and reduction of chattering effects, as well as investigation of rotor dynamics issues. Conventional SMC with constant gains, proposed first order SMC, and proposed quasi-continuous SMC are compared. Nonlinear UAV simulator, validated through in-door experiments, is used to demonstrate the effectiveness of the proposed controls.  相似文献   
80.
Combination of multiple evidences (multiple query formulations, multiple retrieval schemes or systems) has been shown (mostly experimentally) to be effective in data fusion in information retrieval. However, the question of why and how combination should be done still remains largely unanswered. In this paper, we provide a model for simulation and a framework for analysis in the study of data fusion in the information retrieval domain. A rank/score function is defined and the concept of a Cayley graph is used in the design and analysis of our framework. The model and framework have led us to better understanding of the data fusion phenomena in information retrieval. In particular, by exploiting the graphical properties of the rank/score function, we have shown analytically and by simulation that combination using rank performs better than combination using score under certain conditions. Moreover, we demonstrated that the rank/score function might be used as a predictive variable for the effectiveness of combination of multiple evidences.Authors wish to dedicate this paper to the memory of our friend and colleague Professor Jacob Shapiro, who passed away September 2003.Supported in part by the DIMACS NSF grant STC-91-19999 and by NJ Commission.Supported in part by a grant from The City University of New York PSC-CUNY Research Award.  相似文献   
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