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[An experimental study of a hypertext as an innovative teaching tool in learning about occupational risks].

Among innovative techniques, computer-assisted instruction methods and hypertexts deserve particular attention due to the increasing availability of educational software. A hypertext is not a specific programme, rather a type of programme: hypertexts provide different combinations of texts, pictures, graphs, tables, so that learners can browse through information according to their wishes. This study was performed with the aim of comparing two teaching techniques (1. browsing a hypertext with the assistance of a computer, and 2. attending traditional lectures) in the field of occupational and environmental risks for human health. The whole second-year course (21 students) of the School of Environmental and Occupational Hygiene, Faculty of Medicine, University of Pavia, participated in the study. The experimental strategy consisted of 14 working sessions. Students were randomly assigned to 2 groups; one browsed the hypertext and the other attended the lectures. At the end of each session, students performed a 16-item multiple-choice test on the topic covered to assess learning levels. Each student was also requested to judge clarity, interest and usefulness on a 5-point scale. The performance of the students, expressed as a percentage of correct answers, showed that learning lectures is slightly more effective than learning from hypertext browsing. However, the chi 2-test revealed no significant differences between the 2 methods regarding performance when students with more than 75% correct answers were compared. Regarding acceptability of the techniques used, the students considered them equivalent as to interest and usefulness, whereas clarity of the lectures was slightly but significantly higher than the hypertext. Acceptability of hypertext browsing as a learning method was greatly appreciated. Most of the students considered their experience as highly positive: hypertext browsing was considered easy and amusing and the use of the computer for learning was judged most satisfying. Most of the students would like to have the possibility of learning at home, to repeat the experience and extend it to other disciplines. The negative characteristic of hypertext browsing was the "lack of human contact", which makes it impossible to widen knowledge.

Computer-Assisted Instruction↗
PubMed2005

Merging multimedia presentations and semistructured temporal data: a graph-based model and its application to clinical information.

OBJECTIVE: In this paper, we focus on the issue of providing physicians with the capability of representing in a seamless way both temporal aspects of multimedia semistructured data and their temporal presentation requirements. BACKGROUND: Semistructured data are data having some structure, that may be irregular or incomplete and does not necessarily conform to a fixed schema. Semistructured data often contain the description of histories of the considered real world. The eXtensible Markup Language (XML) is becoming a cross compatible and standardized means for representing semistructured clinical data. In the field of medical informatics, there are many ongoing activities concerning XML. In the field of multimedia database systems, the topic related to the integration of several media objects (with their temporal aspects) have been considered both for data modeling and querying issues and for modeling multimedia presentations. METHODOLOGY: We first propose the Multimedia Temporal Graphical Model (MTGM), by representing a clinical database for cardiology patients undergoing cardiac angiographies and then describe it in a formal way. We deal with the problem of expressing MTGM data by XML and of managing MTGM clinical data through an XML-based system. We provide both a technique for translating (a part of) an MTGM database into an XML document and some techniques allowing us to obtain presentations defined by means of the Synchronized Multimedia Integration Language (SMIL) from MTGM presentations. RESULTS: MTGM allows one to represent and store clinical information in a semistructured, temporal, and multimedia database. The physician can define multimedia presentations based on the stored data. Multimedia presentations are then stored in the same MTGM database together with temporal clinical information and are thus represented according to the same data model. A prototype based on an XML native database system has been designed and implemented. DISCUSSION AND CONCLUSIONS: In this work we have considered the theoretical and methodological issues concerning the definition of a general data model for describing temporal and multimedia features of semistructured clinical information. Other research and application oriented features, which have not been considered in MTGM, could be investigated for completing MTGM with regard to its applicability to clinical domains: MTGM does not allow one to express times at different levels of granularities, i.e. with different time units, or with indeterminacy; besides the considered valid time, it could be interesting to manage also other temporal dimensions such as the transaction and availability times. Besides being useful for managing multimedia data stored according to widely accepted standards as MPEG and DICOM, nowadays semistructured data, and XML in particular, are becoming the most important way for expressing and exchanging medical knowledge and data: MTGM can be considered as a data model allowing the seamless representation of both (multimedia and temporal) clinical data and knowledge.

Artificial Intelligence↗
PubMed2005

Oligomeric protein structure networks: insights into protein-protein interactions.

BACKGROUND: Protein-protein association is essential for a variety of cellular processes and hence a large number of investigations are being carried out to understand the principles of protein-protein interactions. In this study, oligomeric protein structures are viewed from a network perspective to obtain new insights into protein association. Structure graphs of proteins have been constructed from a non-redundant set of protein oligomer crystal structures by considering amino acid residues as nodes and the edges are based on the strength of the non-covalent interactions between the residues. The analysis of such networks has been carried out in terms of amino acid clusters and hubs (highly connected residues) with special emphasis to protein interfaces. RESULTS: A variety of interactions such as hydrogen bond, salt bridges, aromatic and hydrophobic interactions, which occur at the interfaces are identified in a consolidated manner as amino acid clusters at the interface, from this study. Moreover, the characterization of the highly connected hub-forming residues at the interfaces and their comparison with the hubs from the non-interface regions and the non-hubs in the interface regions show that there is a predominance of charged interactions at the interfaces. Further, strong and weak interfaces are identified on the basis of the interaction strength between amino acid residues and the sizes of the interface clusters, which also show that many protein interfaces are stronger than their monomeric protein cores. The interface strengths evaluated based on the interface clusters and hubs also correlate well with experimentally determined dissociation constants for known complexes. Finally, the interface hubs identified using the present method correlate very well with experimentally determined hotspots in the interfaces of protein complexes obtained from the Alanine Scanning Energetics database (ASEdb). A few predictions of interface hot spots have also been made based on the results obtained from this analysis, which await experimental verification. CONCLUSION: The construction and analysis of oligomeric protein structure networks and their comparison with monomeric protein structure networks provide insights into protein association. Further, the interface hubs identified using the present method can be effective targets for interface de-stabilizing mutations. We believe this analysis will significantly enhance our knowledge of the principles behind protein association and also aid in protein design.

Animals↗
PubMed1983

[Mechanical strain in the forearm bones].

Knowledge of the physiologic distribution of strain in bone is essential for a successful osteosynthesis by means of compression plate. This method guarantees optimum stability if the plate acts as a tension band. If the side of tensile stresses varies within the bone, strain may not only occur on the side of the plate but also on the opposite cortex. In such cases the distribution of pressure in the fracture gap is of special importance. For determining the distribution of strain on the radius, it is necessary to examine the forces caused by the flexor- and extensor muscles of the wrist and fingers. Additional forces come also from flexor- and extensor muscles of the elbow. The frame formed by the bow-shaped radius and the ulna is of further importance for the distribution of strain. Kind and amount of tension is fundamentally influenced by forearm rotation. Anatomic studies on post-mortem specimens showed how the direction of muscle action to wrist and fingers changed in relation to the position of a plate fixed to the proximal shaft of the radius. This already demonstrates possible variations in the bending forces caused by forearm rotation. An analysis of the distribution of strain in the forearm bones was carried out on a biomechanical model using strain gauges. This method allows the simulation of strain to the skeleton caused by muscle force and the influence of load. The distribution of strain can be studied on the same model in various different positions of elbow and forearm. Six muscles and two muscle groups were simulated by means of wire pulls with calibrated strain gauges; these muscles and muscle groups act, on account of the physiological cross section and their position, as bending forces to the forearm bones in a dorsovolar plane. The tensile force on radius and ulna were each controlled by three strain gauges in four sections. The characteristic quantities of these sections were determined by evaluation of the appropriate computertomograms. With the aid of three strain gauges per section it was possible to assess the strain at any one desired point. Distribution of strain was determined by pull to each "muscle" in the extreme position of forearm rotation and three different positions of flexion to the elbow. The tensile force was expressed on graphs as muscle tension of 2 kp/cm2 per cross section (ill. 6 to 12).(ABSTRACT TRUNCATED AT 400 WORDS)

Biomechanical Phenomena↗
PubMed1995

A classification manager for compositional concept systems exemplarily shown by the AO/ASIF classification of fractures of long bones.

Conventional classification and coding systems represent concept systems by strict hierarchical enumeration and are supported by meaningful codes. Compositional classification is a means for representing concept systems by semantic descriptions. Classification is based on the structure of concept descriptions and explicit hierarchical relationships between their constituents. A classification manager will be presented which is based on the BERNWARD model [1]. BERNWARD is a conceptual graphs formalism and allows the constrained composition of concept descriptions by primitive concepts and roles. It stresses the distinction between generic and partitive relations. Concept descriptions can be classified on the basis of structural criteria for subsumption and part-whole relation. The capabilities of the model, compared to the principles of conventional classification and coding systems, will be exemplified by the AO/ASIF classification of fractures of long bones [2]. This classification is based on 2 axes: topography (long bone and segment) and morphology (type, group, subgroup and quality). It consists of the enumeration of all relevant fractures of long bones which are represented by a compositional meaningful code and by a line drawing. In the demonstrated system, the composition of fracture descriptions is supported by lists of terms and by graphics. The interactive selection of concepts from the space of concepts defined by the implemented classifications is supported by combining the following strategies: entering terms, selecting graphics, adding relevant characteristics to a concept selected before, and navigating through various hierarchies e.g.,generic or partitive hierarchies. These strategies are controlled by different types of compositional restrictions which are: role restrictions, hierarchical restrictions, and coordination restrictions. Role restrictions constrain the addition of specializing characteristics to elements of concept descriptions e.g., the possible complexities of fractures are simple, wedge, and multifragmented. Hierarchical restrictions constrain the generic or partitive refinement of concept elements. For example, every long bone can have the segment "proximal metaphyseal," but only tibia/fibula can have the region "malleolar." Coordination restrictions constrain the coordination of concepts e.g., a frontal fracture of the capitellum can affect the trochlea. Therefore, it is allowed to define a frontal fracture of capitellum and trochlea. Medical observations can be documented by association of selected concepts e.g., a fracture of radius and ulna can be associated to the patient Mr. X. The tools implemented for interactive selection of concepts can be used to rescan documented cases. In contrast to common classification systems, a case can be selected by combining different criteria in BERNWARD. It is possible to look for all female patients with a complex fracture of a long bone of the left upper extremity or to look for all bifocal fractures of the forearm with a wedge fracture of the radius. There is no problem to add new knowledge to the classification manager in the form of another classification. A new classification can be built by using elements of old ones e.g., the classification of the human skeleton is also useful for the AO/ASIF classification. Therefore, parts of classifications can be stored on and loaded from the disk by the demonstrated system. he user environment does not have to be changed to document a different area of medicine because of the conceptual representation of medical knowledge in BERNWARD. The user front-end can be used for all classifications e.g., a relational DBMS for Apple Macintosh systems. Some recursive functions are implemented in a linked Prolog system for effective computation of formal relations between concepts.

Computer Graphics↗