Search results

This paper sets out to give an overview about state‐of‐the‐art optical tomographic image reconstruction algorithms that are based on the equation of radiative transfer (ERT).

An objective function, which describes the discrepancy between measured and numerically predicted light intensity data on the tissue surface, is iteratively minimized to find the unknown spatial distribution of the optical parameters or sources. At each iteration step, the predicted partial current is calculated by a forward model for light propagation based on the ERT. The equation of radiative is solved with either finite difference or finite volume methods.

Tomographic reconstruction algorithms based on the ERT accurately recover the spatial distribution of optical tissue properties and light sources in biological tissue. These tissues either can have small geometries/large absorption coefficients, or can contain void‐like inclusions.

These image reconstruction methods can be employed in small animal imaging for monitoring blood oxygenation, in imaging of tumor growth, in molecular imaging of fluorescent and bioluminescent probes, in imaging of human finger joints for early diagnosis of rheumatoid arthritis, and in functional brain imaging.

Cholangiocarcinoma is an adenocarcinoma of the bile ducts which drain bile from the liver into the small intestine. Unfortunately, most patients are diagnosed at an advanced stage of the disease with almost no chances for surgery, the only potentially curative treatment. As nitinol stents can be used to reduce stricture problems of the bile duct, these can be also considered as potential electrodes for hyperthermia treatments. Previous works show that, in fact, these metallic stents might be used as part of a feasible solution for delivering radiofrequency (RF) energy into a tumor located in a hollow organ to destroy the tumor tissue. However, the tissue lesion induced is not completely uniform due to convective heat transfer associated to the blood flow in the nearby vessels. The purpose of this paper is to study the use of saline solution for modifying the electrical conductivity of the tissue in order to obtain a more uniform lesion.

A numerical analysis using finite element method on a simplified model of the porta hepatis is performed. The tumor tissue is divided in three sections and simulations were performed considering a higher electrical conductivity in the middle section of the tumor, imitating the presence of a saline solution in this part of the tissue.

Results show that it is possible to obtain a more regular volume, by the way the tumor tissue is preferentially heated, although there are still some risks on exceeding the dimension of the bile duct.

This study presents the numerical analysis of a saline‐enhanced RF tissue thermoablation of a cholangiocarcinoma considering a stent‐based electrode. Results point to the possibility of obtaining a more regular volume of damaged tissue in order to heat and preferentially destroy the tumor tissue.

Collaboration between a mechatronics engineer and a biologist resulted in an unlikely application of machine vision. To deduce the density of the porous teeth, the volume had to be found. An expedient method was constructed for scanning the teeth before they had to be returned to their source and a simple method was derived for deducing their volume.

This paper aims to develop and describe an improved process for determining the rate of heat generation in living tissue.

Previous work by the authors on solving the bioheat equation has been updated to include a new localized meshless method which will create a more robust and computationally efficient technique. Inclusion of this technique will allow for the solution of more complex and realistic geometries, which are typical of living tissue. Additionally, the unknown heat generation rates are found through genetic algorithm optimization.

The localized technique showed superior accuracy and significant savings in memory and processor time. The computational efficiency of the newly proposed meshless solver allows the optimization process to be carried to a higher level, leading to more accurate solutions for the inverse technique. Several example cases are presented to demonstrate these conclusions.

This work includes only 2D development of the approach, while any realistic modeling for patient‐specific cases would be inherently 3D. The extension to 3D, as well as studies to improve the technique by decreasing the sensitivity to measurement noise and to incorporate non‐invasive measurement positioning, are under way.

As medical imaging continuously improves, such techniques may prove useful in patient diagonosis, as heat generation can be correlated to the presence of tumors, infections, or other conditions.

This paper describes a new application of meshless methods. Such methods are becoming attractive due to their decreased pre‐processing requirements, especially for problems involving complex geometries (such as patient specific tissues), as well as optimization problems, where geometries may be constantly changing.

Electric fields (EFs) are known to influence cell and tissue activity. This influence can be due to thermal or non-thermal effects. While the non-thermal effects are still matter of discussion, thermal effects might be detrimental for cell and tissue viability due to thermal damage, this fact being exploited by applications like hyperthermia and tissue ablation. The paper aims to discuss these issues.

In this work the authors investigate the influence of thermal damage in the consolidation of bone formation during electrostimulation (ES). The authors introduce a mathematical model describing the migration of osteoprogenitor cells, the thermal variation, the thermal damage accumulation and the formation of new bone matrix in an injury (fracture) site.

Numerical results are in agreement with experimental data and show that EFs more intense than 7.5 V/cm are detrimental for the viability of osteoprogenitor cells and the formation of new bone.

The model is suitable to conduct dosimetry studies in support of other different ES techniques aimed at improving bone and soft tissues repair.

Identifies the three key challenges encountered on international assignments; their impact on assignment adjustment performance and satisfaction; the key skills required to deal effectively with the challenges; and issues associated with training in these skills for internationally assigned managers.

Reproducible images of human fingertips' induced glow (Kirlian radiation) were captured despite extremely unstable nature of living systems' emission. The matrix of correlations between fingertips' radiation in the electromagnetic field of high frequency and systemic features of human organism has been studied.

Weak natural emission of biological object is enhanced and transformed into visual images by gas discharge processes, which proceed in the electromagnetic field of high frequency. Such secondary radiation was found to be reproducible only when special polyethylene membrane is placed between the glass surface of the camera screen and target fingertip (or other living object). Resulting images of fingertips' discharge coronas provide comprehencible information on the whole living system.

Present research resulted in the discovery of previously unknown phenomenon, which turned out to be specific for living systems. It is demonstrated that Kirlian radiation of fingertips can display almost exact replicas (holograms) of organism's internal organs and tissues. Each part of the body is able to provide holographic information on any problematic element of dynamic system. Holodiffractional nature of discovered phenomenon has been confirmed experimentally.

The discovery of new natural phenomenon represents a major step forward regarding both theoretical disciplines and practical biomedicine. Secondary holodiffractional radiation of body parts provides previously unavailable information on dynamic organization of the whole living system. Bioholographic information is already widely used for diagnostics of body/mind pathology.

This paper uses the ideas and concepts of Gilles Deleuze and Félix Guattari and aims to to examine how accounting works in the context of international development.

A case study approach within El Salvador is used. Data sources include archival documents, 35 semi‐structured interviews with field participants, and participant observations. The focus is on the activities of the Inter‐American Development Bank (IDB) and the United Nations Development Agency (UNDP) in the country of El Salvador, showing how complex assemblages of people, technologies such as accounting, and discourses such as accountability come to claim or “territorialize” particular physical and discursive spaces.

The analysis highlights how accounting and its associated actors further the development aspirations of loan beneficiaries; yet at the same time contribute to the “over‐organization” of these actors' social space.

The paper illustrates that the concepts of Deleuze and Guattari – assemblage, desire, Bodies without Organs, and lines of flight to name a few – open up for consideration and analysis a series of field‐specific processes that have previously been largely un‐explored within the accounting literature.

This chapter addresses the alienability or inalienability of the bodily self by looking at continuing legal, economic, and cultural issues surrounding three case studies: the growth of cell lines, live organ transfer, and the practices of “forced prostitution” as a contemporary form of slavery. The essay contends that it is, ironically, Locke and Hegel's shared hyperliberal notion of the self as inalienable property that sustains a potential basis, in law and in culture, for troubling cases of self-alienation which persist in the case studies offered.