Search PubMed⌕ Search

Biomedical subjects

Y Shahar

Publications and source records attributed to Y Shahar.

31 records · Page 2Linked to original sources
PubMed1995

Knowledge-based temporal abstraction in diabetes therapy.

We suggest a general framework for solving the task of creating abstract, interval-based concepts from time-stamped clinical data. We refer to this problem-solving framework as the knowledge-based temporal-abstraction (KBTA) method. The KBTA method emphasizes explicit representation, acquisition, maintenance, reuse, and the sharing of knowledge required for abstraction of time-oriented clinical data. We describe the subtasks into which the KBTA method decomposes its task, the problem-solving mechanisms that solve these subtasks, and the knowledge necessary for instantiating these mechanisms in a particular clinical domain. We have implemented the KBTA method in the RESUME system and have applied it to the task of monitoring the care of insulin-dependent diabetics.

Artificial Intelligence↗
PubMed1994

A temporal-abstraction mediator for protocol-based decision-support systems.

The inability of many clinical decision-support applications to integrate with existing databases limits the wide-scale deployment of such systems. To overcome this obstacle, we have designed a data-interpretation module that can be embedded in a general architecture for protocol-based reasoning and that can support the fundamental task of detecting temporal abstractions. We have developed this software module by coupling two existing systems--RESUME and Chronus--that provide complementary temporal-abstraction techniques at the application and the database levels, respectively. Their encapsulation into a single module thus can resolve the temporal queries of protocol planners with the domain-specific knowledge needed for the temporal-abstraction task and with primary time-stamped data stored in autonomous clinical databases. We show that other computer methods for the detection of temporal abstractions do not scale up to the data- and knowledge-intensive environments of protocol-based decision-support systems.

Artificial Intelligence↗
PubMed1994

Knowledge-based temporal abstraction for diabetic monitoring.

We have developed a general method that solves the task of creating abstract, interval-based concepts from time-stamped clinical data. We refer to this method as knowledge-based temporal-abstraction (KBTA). In this paper, we focus on the knowledge representation, acquisition, maintenance, reuse and sharing aspects of the KBTA method. We describe five problem-solving mechanisms that solve the five subtasks into which the KBTA method decomposes its task, and four types of knowledge necessary for instantiating these mechanisms in a particular domain. We present an example of instantiating the KBTA method in the clinical area of monitoring insulin-dependent-diabetes patients.

Artificial Intelligence↗
PubMed1993

RESUME: a temporal-abstraction system for patient monitoring.

RESUME is a system that performs temporal abstraction of time-stamped data. The temporal-abstraction task is crucial for planning treatment, for executing treatment plans, for identifying clinical problems, and for revising treatment plans. The RESUME system is based on a model of three basic temporal-abstraction mechanisms: point temporal abstraction, a mechanism for abstracting the values of several parameters into a value of another parameter; temporal inference, a mechanism for inferring sound logical conclusions over a single interval or two meeting intervals; and temporal interpolation, a mechanism for bridging nonmeeting temporal intervals. Making explicit the knowledge required for temporal abstraction supports the acquisition and the sharing of that knowledge. We have implemented the RESUME system using the CLIPS knowledge-representation shell. The RESUME system emphasizes the need for explicit representation of temporal-abstraction knowledge, and the advantages of modular, task-specific but domain-independent architectures for building medical knowledge-based systems.

Abstracting and Indexing↗
PubMed1993

Knowledge reuse: temporal-abstraction mechanisms for the assessment of children's growth.

Currently, many workers in the field of medical informatics realize the importance of knowledge reuse. The PROTEGE-II project seeks to develop and implement a domain-independent framework that allows system builders to create custom-tailored role-limiting methods from generic reusable components. These new role-limiting methods are used to create domain- and task-specific knowledge-acquisition tools with which an application expert can generate domain- and task-specific decision-support systems. One required set of reusable components embodies the problem-solving knowledge to generate temporal abstractions. Previously, members of the PROTEGE-II project have used these temporal-abstraction mechanisms to infer the presence of myelotoxicity in patients with AIDS. In this paper, we show that these mechanisms are reusable in the domain of assessment of children's growth.

Artificial Intelligence↗
PubMed1992

A temporal-abstraction system for patient monitoring.

RESUME is a system that performs temporal abstraction of time-stamped data. RESUME is based on a model of three temporal-abstraction mechanisms: point temporal abstraction (a mechanism for abstracting values of several parameters into a value of another parameter); temporal inference (a mechanism for inferring sound logical conclusions over a single interval or two meeting intervals); and temporal interpolation (a mechanism for bridging nonmeeting temporal intervals). Making explicit the knowledge required for temporal abstraction supports the acquisition of that knowledge.

Artificial Intelligence↗
PubMed1991

Temporal-abstraction mechanisms in management of clinical protocols.

We have identified several general temporal-abstraction mechanisms needed for reasoning about time-stamped data, such as are needed in management of patients being treated on clinical protocols: simple temporal abstraction (a mechanism for abstracting several parameter values into one class), temporal inference (a mechanism for inferring sound logical conclusions over a single interval or two meeting intervals), and temporal interpolation (a mechanism for bridging non-meeting temporal intervals). Making explicit the knowledge required for temporal abstractions supports the acquisition of planning knowledge, the identification of clinical problems, and the formulation of clinical-management-plan revisions.

Clinical Protocols↗
PubMed1991

Changes in smoking patterns in young military recruits in relationship to psychosocial characteristics.

We followed 295 young infantry recruits during their first 14 weeks of basic training. The prevalence of smoking increased by 50%. About half of this increase was accounted for by ex-smokers, 57% of whom had resumed the habit. Average education and military psychometric measures of both the baseline smokers and the new smokers were significantly lower than those of the abstaining never-smokers. Asian and North African origin and a lower peer group evaluation score were also risk factors. These relationships were not demonstrated among resuming ex-smokers. The rise in the smoking rate accounts for most of the known rise during full military service. We suggest early preventive measures, especially for the two groups at risk.

Adolescent↗
PubMedDate not supplied

The Asgaard project: a task-specific framework for the application and critiquing of time-oriented clinical guidelines.

Clinical guidelines can be viewed as generic skeletal-plan schemata that represent clinical procedural knowledge and that are instantiated and refined dynamically by care providers over significant time periods. In the Asgaard project, we are investigating a set of tasks that support the application of clinical guidelines by a care provider other than the guideline's designer. We are focusing on the application of the guideline, recognition of care providers' intentions from their actions, and critique of care providers' actions given the guideline and the patient's medical record. We are developing methods that perform these tasks in multiple clinical domains, given an instance of a properly represented clinical guideline and an electronic medical patient record. In this paper, we point out the precise domain-specific knowledge required by each method, such as the explicit intentions of the guideline designer (represented as temporal patterns to be achieved or avoided). We present a machine-readable language, called Asbru, to represent and to annotate guidelines based on the task-specific ontology. We also introduce an automated tool for the acquisition of clinical guidelines based on the same ontology, developed using the PROTEGE-II framework.

Artificial Intelligence↗
PubMedDate not supplied

EON: a component-based approach to automation of protocol-directed therapy.

Provision of automated support for planning protocol-directed therapy requires a computer program to take as input clinical data stored in an electronic patient-record system and to generate as output recommendations for therapeutic interventions and laboratory testing that are defined by applicable protocols. This paper presents a synthesis of research carried out at Stanford University to model the therapy-planning task and to demonstrate a component-based architecture for building protocol-based decision-support systems. We have constructed general-purpose software components that (1) interpret abstract protocol specifications to construct appropriate patient-specific treatment plans; (2) infer from time-stamped patient data higher-level, interval-based, abstract concepts; (3) perform time-oriented queries on a time-oriented patient database; and (4) allow acquisition and maintenance of protocol knowledge in a manner that facilitates efficient processing both by humans and by computers. We have implemented these components in a computer system known as EON. Each of the components has been developed, evaluated, and reported independently. We have evaluated the integration of the components as a composite architecture by implementing T-HELPER, a computer-based patient-record system that uses EON to offer advice regarding the management of patients who are following clinical trial protocols for AIDS or HIV infection. A test of the reuse of the software components in a different clinical domain demonstrated rapid development of a prototype application to support protocol-based care of patients who have breast cancer.

Algorithms↗
PubMedDate not supplied

Semi-automated entry of clinical temporal-abstraction knowledge.

OBJECTIVES: The authors discuss the usability of an automated tool that supports entry, by clinical experts, of the knowledge necessary for forming high-level concepts and patterns from raw time-oriented clinical data. DESIGN: Based on their previous work on the RESUME system for forming high-level concepts from raw time-oriented clinical data, the authors designed a graphical knowledge acquisition (KA) tool that acquires the knowledge required by RESUME. This tool was designed using Protégé, a general framework and set of tools for the construction of knowledge-based systems. The usability of the KA tool was evaluated by three expert physicians and three knowledge engineers in three domains-the monitoring of children's growth, the care of patients with diabetes, and protocol-based care in oncology and in experimental therapy for AIDS. The study evaluated the usability of the KA tool for the entry of previously elicited knowledge. MEASUREMENTS: The authors recorded the time required to understand the methodology and the KA tool and to enter the knowledge; they examined the subjects' qualitative comments; and they compared the output abstractions with benchmark abstractions computed from the same data and a version of the same knowledge entered manually by RESUME experts. RESULTS: Understanding RESUME required 6 to 20 hours (median, 15 to 20 hours); learning to use the KA tool required 2 to 6 hours (median, 3 to 4 hours). Entry times for physicians varied by domain-2 to 20 hours for growth monitoring (median, 3 hours), 6 and 12 hours for diabetes care, and 5 to 60 hours for protocol-based care (median, 10 hours). An increase in speed of up to 25 times (median, 3 times) was demonstrated for all participants when the KA process was repeated. On their first attempt at using the tool to enter the knowledge, the knowledge engineers recorded entry times similar to those of the expert physicians' second attempt at entering the same knowledge. In all cases RESUME, using knowledge entered by means of the KA tool, generated abstractions that were almost identical to those generated using the same knowledge entered manually. CONCLUSION: The authors demonstrate that the KA tool is usable and effective for expert physicians and knowledge engineers to enter clinical temporal-abstraction knowledge and that the resulting knowledge bases are as valid as those produced by manual entry.

Acquired Immunodeficiency Syndrome↗