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Results for “Models, Theoretical”

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At least 181 records · Page 10Linked to original sources
PubMed2003

[Sequential bypass grafting with arterial grafts can be functioned? Assessment of evaluation for function of sequential bypass grafting from theoretical model].

As total arterial revascularization in coronary artery bypass grafting (CABG) has been recommended, a sequential bypass technique using arterial grafts has been induced. We evaluate whether a sequential bypass graft can be functioned or not by using a simple simulation model for coronary circulation analogous to the electrical circuit based on Ohm law. The ratio of flow between graft and native coronary artery was determined by the severity of stenosis in the bypassed vessels and the graft diameter. In selection for sequential bypass technique, these factors should be taken into consideration.

Arteries↗
PubMed2006

[A theoretical model for assessing the relationship between "stage migration" and survival of gastric cancer patients after variable lymph node dissection].

Standard histological procedures identify metastatic gastric cancer in approximately 15% of cases of macroscopically unaltered lymph nodes. Such metastases evade detection after surgery due to inadequate lymph node dissection, thus increasing staging error. Consequently, about 15% of patients suffer from tumor which is actually more advanced than one diagnosed originally.

Adult↗
PubMed2006

Theoretical models in dentistry.

For the exchange between science and practice, a language that is as precise as possible is also required in dentisty. This language is necessarily based on our ideas about the relationships in reality. Since standardization is unavoidable, various methods have been developed in informatics as to how these models can be represented and made more precise. On this basis, it is possible to neutrally discuss the situations in which a given form of treatment is expedient or not. A step-by-step approach to standardization of dental language with the aid of meta models is shown by reference to examples. The medrapid.info service is presented as on approach to making medical and dental language more precise.

Computer Systems↗
PubMedDate not supplied

[A theoretical model of DNA packaging in the phage head].

Statistical model of dsDNA packaging to icosahedral bacteriophage capsid is presented. The model describes intraphage DNA as a globule, i.e. intramolecular liquid crystal. We analyse the free energy of DNA, which has a globulized part inside the phage capsid and coil-like tail outside it. Conditions when processes of DNA movement into capsid or back are thermodynamically favorable are investigated. These processes are not accompanied with any thermal effects. It is not "all or none" type process, i.e. intermediate stable states are possible. The role of DNA interaction with the capsid inner wall is considered. The essential model abilities for qualitative explanation of experimental data are exhibited.

Bacteriophages↗
PubMed1990

A testable theoretical model for magnetotherapy potentially applicative to such diverse concerns as oncogenic, CNS trophic factor and viral disorders.

Physiologic magnetic fields of the order 10(-8) gauss have been unified with their propitiators: quantum genetic particles, the gravitational potential of which is about an erg. As these fields are applied to the equation for solenoidal models, B = micro NI/L, currents of about a microampere are derived; in perfect accord with recent clinical data indicating the therapeutic efficacy of weak currents in repair and growth of soft tissue, bone and nerve. The mechanism of reorientation of spin angular momentum of leptons and baryons influencing molecular magnetic domains to bring about 'particle jumps' is presented so that a clinical picture results. The clinical picture is that of an organism placed at right angles to flux lines in the midst of a solenoid immersed in water exposed then to exogenously applied resonant physiologic magnetic fields which convert malalligned atomic lattices of oncogenes and associated particles to homologous normal structures.

Animals↗
PubMed1990

Uptake and metabolism of retinoic acid induces inhibition of cell growth: a study in a rat rhabdomyosarcoma cell line (BA-HAN-1C) using nonlinear theoretical models.

Retinoic acid causes a significant inhibition of cell growth of the tumor cell line BA-HAN-1C. This growth inhibition is the same whether the cells are treated with a pulse dose of retinoic acid (RA) or continuously expand to RA. The determination of RA and its degradation products within the culture medium and in the cells showed that after 24 hours 13-cis-RA was the major retinoid in all cells (96 ng/10(6) cells); all-trans-RA represented 56 ng/10(6) cells. After 48 hours 4-hydroxy-RA and a small amount of 5,6-epoxy-RA was found in the cells and also in the culture medium. 4-hydroxy-RA increased up to 96 hours, whereas 13-cis- and all-trans-RA were not detectable in the cells after 96 hours. We conclude that the BA-HAN-1C cells take up and metabolize RA. Nonlinear fit analysis of the time behavior of the RA concentration in medium demonstrates that the RA uptake unexpectedly follows a mono-exponential time function. Discussion of the experimental results in connection with a proper compartment model shows that uptake and metabolism of RA cannot be described really by a first order kinetics. The mathematical analysis leads to a more complicated kinetic model with certain restrictions for the corresponding rate constants.

Animals↗
PubMed1989

Social justice and health care. A theoretical model.

Individual health care and the health care system are normally assessed in terms of efficiency, efficacy and cost-effectiveness, using empirical data regarding sickness profiles, hospital beds per population, cost per patient, etc. In this paper it is argued that assessment of health care in terms of the concepts of justice and injustice is both possible and necessary. A simple model is proposed to assess whether health care can be considered just or unjust in a specific context. The model uses the same data base as is normally used to assess the effectiveness and efficiency of health care systems.

Delivery of Health Care↗