American Journal of Biomedical Engineering最新文献

{"title":"A New Interactive 3-D Numerical Model of the Human Mandible for Peri-Implant Analysis in-Vivo Compared With Cone Beam Computed Tomography 3-D Quality","authors":"R. Moustafa, T. M. Nassef, M. Alkhodary, M. Marei, Magdy A. Awadalla","doi":"10.5923/J.AJBE.20120201.02","DOIUrl":"https://doi.org/10.5923/J.AJBE.20120201.02","url":null,"abstract":"Dental implants have been widely and increasingly used in the past few decades to support and retain partial and complete dental prosthesis. The fear of failure due to mechanical overloading increased the need for stress-strain analysis along bone-implant interface of the ever growing designs of dental implants. Finite element analysis (FEA) was used by many authors to evaluate stresses around dental implants and to predict their survivability, where to extract a robust FEA model a realistic information system must be used. In this study an interactive 3-D model was retrieved from Computed Tomography (CT) images utilizing, a proposed software are used to obtain high image quality of the jaw bones scanned by 3-D CT compared with Cone Beam Computed tomography (CBCT) output. Identification of different anatomical regions set for mandible cortical and spongy bones with soft tissues by generated 3-D models and validated with real measurements from solid model.","PeriodicalId":7620,"journal":{"name":"American Journal of Biomedical Engineering","volume":"79 1","pages":"9-16"},"PeriodicalIF":0.0,"publicationDate":"2012-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89838298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulation of Action Potential Propagation in Cardiac Ventricular Tissue Using an Efficient PDE Model","authors":"S. Sabzpoushan, A. Ghodrat","doi":"10.5923/J.AJBE.20120201.03","DOIUrl":"https://doi.org/10.5923/J.AJBE.20120201.03","url":null,"abstract":"Signal transmission in the form of propagating waves of electrical excitation is a fast type of communication and coordination between cells that is known in cardiac tissue as the action potential.In this article we used an efficient model of cardiac ventricular cell that is based on partial differential equations(PDE).After that a computational algorithm for action potential propagation was represented that according to this algorithm and proposed efficient model, We demonstrated action potential propagation in one-dimensional (1D) and two-dimensional (2D) space lattices using the central finite-difference method.In addition we investigated the effect of obstacles on the propagation of normal action potential using represented 2D excitable medium.Our results show that proposed efficient model, represented algorithm and excitable media are suitable for simulation of action potential propagation in cardiac tissue. Traveling waves transmit information through space and always an excitable medium serves to promote propagation. an excitable medium is typically comprised of a continuous set of locally excitable regions,which can be both inde- pendently stimulated and inhibited.these media exhibit a sensitivity threshold blow which the media persist undis- turbed at a stable resting state.while subthreshold perturba- tions are rapidly diminished, greater than threshold signals induce an abrupt local transformation within a portion of the medium. shortly after this change occurs, the region becomes transiently refractory to further perturbation, after which it relaxes to the resting state. The bioelectric activity of cardiac cells results from the transport processes of ionic species across the membrane through voltage-gated ion channels. The ion channels act as gates that regulate the permeabilities of sodium, potassium and calcium ions. At rest, the cell maintains a constant, negative transmembrane voltage, called the resting potential. However, if a strong enough depolarizing current is passed through the membrane, the cell departs from equilibrium and responds with a sharp change in the transmembrane voltage followed by a return to the resting state. This rapid course of the transmembrane voltage is called action poten- tial (AP) that is the fastest form of communications in the cardiac excitable tissue. Conduction of AP in the heart occurs by electrotonic mechanisms, in which the local","PeriodicalId":7620,"journal":{"name":"American Journal of Biomedical Engineering","volume":"32 1","pages":"17-23"},"PeriodicalIF":0.0,"publicationDate":"2012-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82026188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Transforming Growth Factor-β1 in Biological Regulation of Primary Chondrocyte","authors":"S. A. Khaghani, M. Denyer, M. Youseffi","doi":"10.5923/J.AJBE.20120201.01","DOIUrl":"https://doi.org/10.5923/J.AJBE.20120201.01","url":null,"abstract":"The effect of transforming growth factors-β (TGF-βs) in the regulation and control of cell growth is widely studied, but the capability of these cytokines to regulate chondrocyte cell functions such as migration, cell death, prolifera- tion, differentiation and wound repair is not clearly understood. In this work the effect of TGF-β1 on the biological regula- tion of chondrocyte was evaluated using a model wound closure assay. The experiments were carried out on primary chon- drocyte cells with fibroblast like and chondrocytic phenotypes. The cells were isolated from knee articular cartilage of five day old Sprague-Dawley neonate rats and seeded at low density to obtain a fibroblast like morphology. Chondrocytes with chondrocytic phenotype were derived by seeding at high density.The results revealed that TGF-β1 slowed down prolifera- tion and migration of cells into a model wound. It was also found that cell attachment, as determined by the detachment time during trypsinization, was greater for cells with a fibroblast like morphology when compared with cells exhibiting chondrocytic morphology. Treatment with TGF-β1 was found to increase the detachment times of fibroblast like chondro- cytes, indicating that TGF-β1enhanced cell attachment of this cell type, whilst treatment with TGF-β1 decreased detach- ment time for the chondrocytic type chondrocyte cells indicating that TGF-β1 decreased cell attachment in these cells.","PeriodicalId":7620,"journal":{"name":"American Journal of Biomedical Engineering","volume":"437 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2012-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77815742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Study on the Effect of the Inter-Sources Distance on the Performance of the SSVEP-Based BCI Systems","authors":"S. N. Resalat, S. Setarehdan","doi":"10.5923/J.AJBE.20120201.04","DOIUrl":"https://doi.org/10.5923/J.AJBE.20120201.04","url":null,"abstract":"Brain Computer Interfacing (BCI) systems, which are a new communicating channel between humans and the computers are growing rapidly. One such a method is based on the Steady State Visual Evoked Potentials (SSVEP), which can be recorded during visual stimulating of the subject by a twinkling light source with a fixed frequency. An important parameter to be considered is the effect of the inter-sources distance on the accuracy of such BCI systems. In particular inter-sources (LEDs) distances of 4, 14, 24, 44 and 64 cm when the sources plane is located 60 cm away from the subject's eyes (producing inter-sources visual angles of 3.8°, 13.4°, 22.6°, 40.2° and 56° respectively) were examined. In addition, four different sweep lengths of 0.5, 1, 2 and 3 seconds are considered. In addition, due to the usage of the AR models for feature extraction from the SSVEP signals, selection of the best AR model together with the best classifier among the LDA, the SVM and the Naive Bayes are studied. It is showed that the BCI system with D=44 cm, AR order of 13 and either the LDA or the SVM classifiers could produce the best results compared to the other cases.","PeriodicalId":7620,"journal":{"name":"American Journal of Biomedical Engineering","volume":"10 1","pages":"24-31"},"PeriodicalIF":0.0,"publicationDate":"2012-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86705970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}