853 research outputs found
Evidence for Unusually Strong Near-field Ground Motion on the Hanging Wall of the San Fernando Fault during the 1971 Earthquake
Reports of unusually intense ground motions in the very near fields of faults that have ruptured during earthquakes are becoming more common, particularly with the markedly increased worldwide strong-motion instrumentation in recent years (e.g., Heaton and Wald, 1994). The reported ground motions are sufficiently strong to have significant potential engineering impact (Hall et al., 1995). In addition to fault proximity, two other factors that have contributed to unusually high strong motions are rupture directivity (e.g., Somerville et al., 1997) and locations on the hanging walls of thrust faults (e.g., Nason, 1973; Abrahamson and Somerville, 1996; Brune, 1996a; Brune, 1996b). Perhaps nowhere has the sharp distinction between damage on the hanging wall and footwall of a thrust fault been more dramatically documented than during the 1945 Mikawa earthquake, Japan (Iida, 1985)
The role of illness scripts in the development of medical diagnostic expertise: Results from an interview study
In this article, we describe a study in which some current ideas about illness scripts are tested. Participants at 4 levels of medical expertise were asked to describe either a prototypical patient or the clinical picture associated with a number of different diseases. It was found that participants at intermediate levels of expertise mentioned, both absolutely and relatively, many enabling conditions (patient contextual factors such as sex, age, medical history, and occupation) when asked to describe a prototypical patient with a disease, whereas the instruction to describe the clinical picture of a disease revealed a monotonic relation with expertise level. The amount of biomedical information in the descriptions decreased with increasing expertise level for both types of instruction. In addition, a positive relation was found between number of actual patients seen with a particular disease and number of enabling conditions mentioned. These results were interpreted as supportive of the present conceptualization of the illness script theory
Random and Correlated Phases of Primordial Gravitaional Waves
The phases of primordial gravity waves is analysed in detail within a quantum
mechanical context following the formalism developed by Grishchuk and Sidorov.
It is found that for physically relevant wavelengths both the phase of each
individual mode and the phase {\it difference} between modes are randomly
distributed. The phase {\it sum} between modes with oppositely directed
wave-vectors, however, is not random and takes on a definite value with no rms
fluctuation. The conventional point of view that primordial gravity waves
appear after inflation as a classical, random stochastic background is also
addressed.Comment: 14 pages, written in REVTE
Effects of tutor-related behaviours on the process of problem-based learning
Tutors in a Problem-Based Learning (PBL) curriculum are thought to play active roles in guiding students to develop frameworks for use in the construction of knowledge. This implies that both subject-matter expertise and the ability of tutors to facilitate the learning process must be important in helping students learn. This study examines the behavioural effects of tutors in terms of subject-matter expertise, social congruence and cognitive congruence on studentsâ learning process and on their final achievement. The extent of studentsâ learning at each PBL phase was estimated by tracking the number of relevant concepts recalled at the end of each learning phase, while student achievement was based on studentsâ ability to describe and elaborate upon the relationship between relevant concepts learned. By using Analysis of Covariance, social congruence of the tutor was found to have a significant influence on learning in each PBL phase while all of the tutor-related behaviours had a significant impact on student achievement. The results suggest that the ability of tutors to communicate informally with students and hence create a less threatening learning environment that promotes a free flow exchange of ideas, has a greater impact on learning at each of the PBL phases as compared to tutorsâ subject-matter expertise and their ability to explain concepts in a way that is easily understood by students. The data presented indicates that these tutor-related behaviours are determinants of learning in a PBL curriculum, with social congruence having a greater influence on learning in the different PBL phases
Problem formulation by medical students: an observation study
<p>Abstract</p> <p>Background</p> <p>Medical problems are often complex and ill-structured. In formulating the problem, one has to discriminate pertinent elements from irrelevant information in order to effectively find a solution. In this observation study, we describe how medical students formulate the problem of a complex case.</p> <p>Methods</p> <p>32 third year medical students were presented with a complex case of endocarditis. They were asked to synthesize the case and give the best formulation of the problem. They were then asked to provide a diagnosis. A subsequent group of 25 students were presented with the problem already formulated and were also asked for the diagnosis. We analyzed the student's problem formulations using the presence or absence of essential elements of the case, the use of higher-order concepts and the use of relations between concepts.</p> <p>Results</p> <p>12/32 students presented with the case made the correct diagnosis. Diagnostic accuracy was significantly associated with the use of higher-order concepts and relations between concepts. Establishing explicit relations was particularly important. Almost all students who missed the diagnosis could not elicit any relations between concepts but only reported factual observations. When presented with an already formulated problem, 19/25 students made the correct diagnosis. (p < 0.05)</p> <p>Conclusion</p> <p>When faced with a complex new case, students may not have the structured knowledge to recognize the nature of the problem. They have to build new schema or problem representation. Our observations suggest that this process involves using higher-order concepts and establishing new relations between concepts. The fact that students could recognize the disease when presented with a formulated problem but had more difficulty when presented with the original complex case indicates that knowledge of the clinical features may be necessary but not sufficient for problem formulation. Our hypothesis is that problem formulation represents a distinct ability.</p
The influence of medical expertise, case typicality and illness script component on case processing and disease probability estimates
The present study investigated the influence of medical expertise, case typicality, and illness script component (enabling conditions vs. consequences) on the speed of case informati
A population of luminous accreting black holes with hidden mergers
Major galaxy mergers are thought to play an important part in fuelling the
growth of supermassive black holes. However, observational support for this
hypothesis is mixed, with some studies showing a correlation between merging
galaxies and luminous quasars and others showing no such association. Recent
observations have shown that a black hole is likely to become heavily obscured
behind merger-driven gas and dust, even in the early stages of the merger, when
the galaxies are well separated (5 to 40 kiloparsecs). Merger simulations
further suggest that such obscuration and black-hole accretion peaks in the
final merger stage, when the two galactic nuclei are closely separated (less
than 3 kiloparsecs). Resolving this final stage requires a combination of
high-spatial-resolution infrared imaging and high-sensitivity hard-X-ray
observations to detect highly obscured sources. However, large numbers of
obscured luminous accreting supermassive black holes have been recently
detected nearby (distances below 250 megaparsecs) in X-ray observations. Here
we report high-resolution infrared observations of hard-X-ray-selected black
holes and the discovery of obscured nuclear mergers, the parent populations of
supermassive-black-hole mergers. We find that obscured luminous black holes
(bolometric luminosity higher than 2x10^44 ergs per second) show a significant
(P<0.001) excess of late-stage nuclear mergers (17.6 per cent) compared to a
sample of inactive galaxies with matching stellar masses and star formation
rates (1.1 per cent), in agreement with theoretical predictions. Using
hydrodynamic simulations, we confirm that the excess of nuclear mergers is
indeed strongest for gas-rich major-merger hosts of obscured luminous black
holes in this final stage.Comment: To appear in the 8 November 2018 issue of Nature. This is the
authors' version of the wor
Student and tutor perceptions on attributes of effective problems in problem-based learning
This study aimed to identify the attributes that students and tutors associated with effective PBL problems, and assess the extent to which these attributes related to the actual effectiveness of problems. To this end, students and tutors in focus groups were asked to discuss about possible attributes of effective problems. The same participants were then asked to individually and independently judge eight sample problems they had worked with. Text analysis of the focus group discussion transcripts identified eleven problem attributes. Participants' judgments of the sample problems were then frequency-scored on the eleven problem attributes. Relating the participants' judgments with the entire student cohort's grades yielded high and significant correlations, suggesting that the eleven problem attributes reflect aspects of problem effectiveness
Contemporary understanding of riots: classical crowd psychology, ideology and the social identity approach
This article explores the origins and ideology of classical crowd psychology, a body of theory reflected in contemporary popularised understandings such as of the 2011 English âriotsâ. This article argues that during the nineteenth century, the crowd came to symbolise a fear of âmass societyâ and that âclassicalâ crowd psychology was a product of these fears. Classical crowd psychology pathologised, reified and decontextualised the crowd, offering the ruling elites a perceived opportunity to control it. We contend that classical theory misrepresents crowd psychology and survives in contemporary understanding because it is ideological. We conclude by discussing how classical theory has been supplanted in academic contexts by an identity-based crowd psychology that restores the meaning to crowd action, replaces it in its social context and in so doing transforms theoretical understanding of âriotsâ and the nature of the self
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