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At least 1,459 records · Page 81Linked to original sources
PubMed1994

Practicing oncology in provincial Mexico: a narrative analysis.

This paper examines the discourse of oncologists treating cancer in a provincial capital of southern Mexico. Based on an analysis of both formal interviews and observations of everyday clinical practice, it examines a set of narrative themes they used to maintain a sense of professionalism and possibility as they endeavored to apply a highly technologically dependent biomedical model in a resource-poor context. They moved between coexisting narrative frameworks as they addressed their formidable problems of translating between theory and practice. In a biomedical narrative frame, they drew on biomedical theory to produce a model of cellular dysfunction and of clinical intervention. However, limited availability of diagnostic and treatment techniques and patients inability or unwillingness to comply, presented serious constraints to the application of this model. They used a practical narrative frame to discuss the socio-economic issues they understood to be underlying these limitations to their clinical practice. They did not experience the incongruity between theory and practice as a continual challenge to their biomedical model, nor to their professional competency. Instead, through a reconciling narrative frame, they mediated this conflict. In this frame, they drew on culturally specific concepts of moral rightness and order to produce accounts that minimized the problem, exculpated themselves and cast blame for failed diagnosis and treatment. By invoking these multiple, coexisting narrative themes, the oncologists sustained an open vision of their work in which deficiencies and impotency were vindicated, and did not stand in the way of clinical practice.

Communication↗
PubMed2006

A comparison of laser-ultrasound detection system sensitivity with a broad-band ultrasonic source for biomedical applications.

BACKGROUND: Laser ultrasound detection systems are used for noninvasive imaging of internal structures and function of soft tissues. The detection systems with a high sensitivity can be used for detecting small tumors located deeply in human tissues, such as the breast. In this study, the sensitivity of existing ultrasonic detection systems has been compared experimentally by using thermoelastic waves as a broadband ultrasonic source. METHODS: For the comparison, an optical stress transducer, a polyvinylidene difluoride (PVDF) sheet and a calibrated PVDF needle hydrophone were used. To ensure that all detection systems were interrogated by the same ultrasonic field, a small optical instrument was constructed to fix the generating laser head. The sensitivity was evaluated by measuring signal-to-noise ratios (SNRs) and noise equivalent pressures (NEPs). RESULTS: The PVDF system, with a 4 kPa NEP, has a 22-dB better performance than the optical stress transducer. The optical stress transducer showed nearly the same sensitivity as the hydrophone for detecting ultrasound waves at a 1-cm distance. CONCLUSIONS: PVDF detection system provides a useful tool for imaging of soft tissues because of its high sensitivity and broadband detection range.

Biomedical Technology↗
PubMed2005

Part-whole representation and reasoning in formal biomedical ontologies.

OBJECTIVE: Biomedical ontologies are typically structured in a biaxial way, reflecting both a taxonomic (is-a) and a partonomic (part-of) hierarchy. Commonly used biomedical terminologies, which incorporate such distinctions excel in terms of broad coverage but lack a rigid formal foundation. The latter, however, is a prerequisite for automated reasoning. For the biomedical domain, it is not only crucial to cope with ontological dependencies between wholes and their parts but also with specific reasoning patterns which underlie the propagation of roles across partonomic hierarchies. METHODS: We scale down part-whole reasoning to subsumption-based taxonomic reasoning within the formal framework of a parsimonious variant of description logics (viz. ALC). RESULTS: We provide a formal basis for ontological engineering in the domain of biomedicine, as far as part-whole relationships are concerned, by addressing typical reasoning patterns encountered in this domain.

Artificial Intelligence↗
PubMed2005

Case-based object recognition for airborne fungi recognition.

OBJECTIVE: Model-based object recognition is a well-known task in Computer Vision. Usually, one object that can be generalized by a model should be detected in an image based on this model. Biomedical applications have the special quality that one object can have a great variation in appearance. Therefore the appearance of this object cannot be generalized by one model. A set of cases of the appearance of this object (sometimes 50 cases or more) is necessary to detect this object in an image. The recognition method is rather case-based object recognition than model-based object recognition. Case-based object recognition is a challenging task. METHODS AND MATERIAL: It puts special requirements to the similarity measure and needs a matching algorithm that can work fast in a large number of cases. It also needs a case acquisition procedure that can capture the great variation in appearance of an object and generalize these data into a case description. In this paper we describe the chosen case representation, the similarity measure and the matching as well as the case acquisition procedure. We evaluate our method based on a large enough set of digital images containing biological objects such as fungi spores. RESULTS: We can show that the similarity measure is superior to detect the objects in the images. The developed method for case acquisition and learning of generalized cases allows us to learn interactively a sufficient number of cases that are further stored into our case base. Finally, we give results on the performance of the system by calculating the recognition rate. CONCLUSION: These result show that we have developed a novel similarity measure for object detection in digital grey-level images and a novel procedure for case acquisition and learning that allows us to learn a sufficiently large enough case base and to generalize over a group of cases.

Algorithms↗
PubMed2004

Fatigue characteristics of bioactive glass-ceramic-coated Ti-29Nb-13Ta-4.6Zr for biomedical application.

A new surface-coating method by which CaP invert glass is used to improve the bioactivity of titanium alloys has been developed recently. In this method, the powder of CaP invert glass (CaO-P2O5-TiO2-Na2O) is coated on the surface of titanium alloy samples and heated between 1073 and 1123 K. With this treatment, a calcium phosphate layer mainly containing beta-Ca3(PO4)2 phase can be coated easily on titanium alloy samples. In the present study, the effect of this coating process on the fatigue properties of Ti-29Nb-13Ta-4.6Zr, a new metastable beta alloy for biomedical applications, has been investigated. The fatigue endurance limit of the coated alloy was found to be about 15% higher than that of uncoated alloy, as a result of the formation of a hard (alpha + beta) layer and a small amount of the omega phase during the coating process. The coating exhibits excellent adhesion to the substrate during the tensile and fatigue tests. Subsequent ageing at 673 K for 259.2 ks greatly improves the fatigue resistance of the coated alloy due to isothermal omega phase precipitation, and does not have obvious detrimental effect on the coating properties.

Adhesiveness↗
PubMed2006

Context awareness in health care: a review.

BACKGROUND: Health care systems will integrate new computing paradigms in the coming years. Context-awareness computing is a research field which often refers to health care as an interesting and rich area of application. AIM: Through a survey of the research literature, we intended to derive an objective view of the actual dynamism of context awareness in health care, and to identify strengths and weaknesses in this field. METHODS: After discussing definitions of context, we proposed a simple framework to analyse and characterize the use of context through three main axes. We then focused on context-awareness computing and reported on the main teams working in this area. We described some of the context-awareness projects in health care. A deeper analysis of the hospital-based projects demonstrated the gap between recommendations expressed for modelling context awareness and the actual use in a prototype. Finally, we identified pitfalls encountered in this area of research. RESULTS: A number of opportunities remain for this evolving field of research. We found relatively few groups with such a specific focus. As yet there is no consensus as to the most appropriate models or attributes to include in context awareness. We conclude that a greater understanding of which aspects of context are important in a health care setting is required; the inherent sociotechnical nature of context-aware applications in health care; and the need to draw on a number of disciplines to conduct this research.

Biomedical Technology↗
PubMed2004

Pseudo-thermosetting chitosan hydrogels for biomedical application.

To prepare transparent chitosan/beta-glycerophosphate (betaGP) pseudo-thermosetting hydrogels, the deacetylation degree (DD) of chitosan has been modified by reacetylation with acetic anhydride. Two methods (I and II) of reacetylation have been compared and have shown that the use of previously filtered chitosan, dilution of acetic anhydride and reduction of temperature in method II improves efficiency and reproducibility. Chitosans with DD ranging from 35.0 to 83.2% have been prepared according to method II under homogeneous and non-homogeneous reacetylation conditions and the turbidity of chitosan/betaGP hydrogels containing homogeneously or non-homogeneously reacetylated chitosan has been investigated. Turbidity is shown to be modulated by the DD of chitosan and by the homogeneity of the medium during reacetylation, which influences the distribution mode of the chitosan monomers. The preparation of transparent chitosan/betaGP hydrogels requires a homogeneously reacetylated chitosan with a DD between 35 and 50%.

Biomedical Technology↗
PubMed2004

Pseudo-thermosetting chitosan hydrogels for biomedical application.

To prepare transparent chitosan/beta-glycerophosphate (betaGP) pseudo-thermosetting hydrogels, the deacetylation degree (DD) of chitosan has been modified by reacetylation with acetic anhydride. Two methods (I and II) of reacetylation have been compared and have shown that the use of previously filtered chitosan, dilution of acetic anhydride and reduction of temperature in method II improves efficiency and reproducibility. Chitosans with DD ranging from 35.0 to 83.2% have been prepared according to method II under homogeneous and non-homogeneous reacetylation conditions and the turbidity of chitosan/betaGP hydrogels containing homogeneously or non-homogeneously reacetylated chitosan has been investigated. Turbidity is shown to be modulated by the DD of chitosan and by the homogeneity of the medium during reacetylation, which influences the distribution mode of the chitosan monomers. The preparation of transparent chitosan/betaGP hydrogels requires a homogeneously reacetylated chitosan with a DD between 35 and 50%.

Biomedical Technology↗