Transport lattice models of heat transport in skin with spatially heterogeneous, temperature-dependent perfusion

BACKGROUND: Investigation of bioheat transfer problems requires the evaluation of temporal and spatial distributions of temperature. This class of problems has been traditionally addressed using the Pennes bioheat equation. Transport of heat by conduction, and by temperature-dependent, spatially heterogeneous blood perfusion is modeled here using a transport lattice approach. METHODS: We represent heat transport processes by using a lattice that represents the Pennes bioheat equation in perfused tissues, and diffusion in nonperfused regions. The three layer skin model has a nonperfused viable epidermis, and deeper regions of dermis and subcutaneous tissue with perfusion that is constant or temperature-dependent. Two cases are considered: (1) surface contact heating and (2) spatially distributed heating. The model is relevant to the prediction of the transient and steady state temperature rise for different methods of power deposition within the skin. Accumulated thermal damage is estimated by using an Arrhenius type rate equation at locations where viable tissue temperature exceeds 42°C. Prediction of spatial temperature distributions is also illustrated with a two-dimensional model of skin created from a histological image. RESULTS: The transport lattice approach was validated by comparison with an analytical solution for a slab with homogeneous thermal properties and spatially distributed uniform sink held at constant temperatures at the ends. For typical transcutaneous blood gas sensing conditions the estimated damage is small, even with prolonged skin contact to a 45°C surface. Spatial heterogeneity in skin thermal properties leads to a non-uniform temperature distribution during a 10 GHz electromagnetic field exposure. A realistic two-dimensional model of the skin shows that tissue heterogeneity does not lead to a significant local temperature increase when heated by a hot wire tip. CONCLUSIONS: The heat transport system model of the skin was solved by exploiting the mathematical analogy between local thermal models and local electrical (charge transport) models, thereby allowing robust, circuit simulation software to obtain solutions to Kirchhoff's laws for the system model. Transport lattices allow systematic introduction of realistic geometry and spatially heterogeneous heat transport mechanisms. Local representations for both simple, passive functions and more complex local models can be easily and intuitively included into the system model of a tissue

Complexity Theory for a New Managerial Paradigm: A Research Framework

In this work, we supply a theoretical framework of how organizations can embed complexity management and sustainable development into their policies and actions. The proposed framework may lead to a new management paradigm, attempting to link the main concepts of complexity theory, change management, knowledge management, sustainable development, and cybernetics. We highlight how the processes of organizational change have occurred as a result of the move to adapt to the changes in the various global and international business environments and how this transformation has led to the shift toward the present innovation economy. We also point how organizational change needs to deal with sustainability, so that the change may be consistent with present needs, without compromising the future

The Imbalance Between Experiment and Theory in Biology: The Need for Theory-Directed Modeling

In biological and biomedical research, the vast majority of resources are focused on conducting experiments. Most of these experiments utilize animals. Only a tiny amount of resources is spent on theory and modeling. It is our contention and the basic theme of this paper that the imbalance between theory and experiment in biology produces very poor science. The implications of which are that many of the experiments conducted have little real scientific meaning or value and, therefore, go hand-in-hand with unnecessary animal use and suffering. Given the finite resources available for research, the redirection of significant resources from an almost entirely experimental approach into one with an emphasis on more theoretical and modeling activity will achieve a much better scientific result while considerably reducing the number of animals used in biological research

Markkinointistrategia: Case Kartanon Ratsu

Markkinoinnin suunnitteleminen voi olla haastavaa etenkin pienelle ja uudelle yritykselle, jolla on rajalliset resurssit. Markkinointiin tulisi panostaa, mutta tähän ei aina ole mahdollisuutta. Tämän tutkimuksen tarkoituksena onkin luoda toimeksiantajalle käyttökelpoinen markkinointistrategia, jonka perusteella on annettu markkinointisuunnitelman muodossa toimenpide-ehdotuksia. Markkinointia suunnitellessa on myös hyvä kuunnella asiakasta, jolloin saadaan todennäköisemmin luotua toimintakelpoisempia suunnitelmia. Tämän vuoksi tutkimusta varten on haastateltu toimeksiantajayrityksen kanta-asiakkaita heidän odotuksistaan ja tarpeistaan. Oheinen tutkimus toteutettiin keväällä 2013 toimeksiantona Kartanon Ratsulle, joka on hevos- ja ratsastusvarusteita myyvä yritys. Kartanon Ratsu on toiminut nykyisten omistajien alla vuoden 2012 kesäkuusta lähtien, joten yritys on vielä melko nuori. Hevos- ja etenkin ratsastusharrastus on kuitenkin jatkuvasti kasvussa, joten myös varustemyynnin alalla kasvua odotetaan olevan. Kilpailutilanne on haastava sinänsä, että alalla on pitkäaikaisia vakiintuneita toimijoita, mutta Kartanon Ratsu on onnistunut erikoistumaan etenkin tuotevalikoiman kohdalla. Kanta-asiakkaille kohdistettu asiakastyytyväisyystutkimus toteutettiin empiirisenä tutkimuksena ja analysointiin käytettiin kvantitatiivisia menetelmiä. Kysely toteutettiin Webropol-ohjelman avulla ja tulokset analysoitiin Microsoft Excel 2010 avulla. Tutkimukseen saatiin 17 vastausta muodostaen vastausprosentiksi 17,89 %. Tutkimustulosten perusteella Kartanon Ratsun kanta-asiakkaan ovat keskimäärin tyytyväisiä yritykseen. Etenkin tuotevalikoiman tietyt tuotemerkit saivat kiitosta. Nämä ovat myöskin ne tuotemerkit joiden perusteella yritys on erikoistunut alalla. Muilta osin tuotevalikoimaan toivottiin joitakin muutoksia ja lisäyksiä. Itse kanta-asiakkuudessa olisi tutkimuksen perusteella vielä parannettavaa, ja kehitysehdotuksia saatiin vastaajilta. Näiden tulosten perusteella voitiin muodostaa markkinointisuunnitelma Kartanon Ratsulle.Marketing planning can be seen as challenging - especially for small and new companies with limited resources. Companies should invest in marketing but this is not always possible. Therefore it is the aim of the study to create a marketing strategy for the employing company. Based on the strategy a marketing plan with recommendations for marketing actions will be given. When planning marketing it is also important to listen to the customers, this will make it more likely for the plan to be useful in practice. In order to get this information loyalty customers of the company have been interviewed for their expectations and needs. The following study was executed during spring 2013 for the company Kartanon Ratsu, a retailer for horse and riding equipment. Its current owners have led Kartanon Ratsu since summer 2012 so it is a relevantly young actor in the market. Horses and riding are though a growing hobby in Finland, so there are expectations for the demand to rise. The market is challenging since there are a few companies that have established their presence in the market but Kartanon Ratsu has managed to differentiate especially with its product mix. The customer satisfaction survey was conducted as an empirical research and analyzed with quantitative methods. The Webropol program was used for collecting responses and data was analyzed with help of Microsoft Excel 2010. 17 responses were received making the response rate 17,89 %. Based on the survey the loyalty customers of Kartanon Ratsu are relevantly satisfied with the company. In particular certain brands were appreciated. These brands are also the ones that Kartanon Ratsu has differentiated in the market. Otherwise the product mix received ideas for improvement. According to the survey, the actual customer loyalty program should also be improved. The respondents gave recommendations for improvement. Based on the results a marketing plan for Kartanon Ratsu could be formed

Multi-perspective modelling of complex phenomena

This conceptual paper discusses the limitations of a single-perspective hierarchical approach to modelling and proposes multi-perspective modelling as a way to overcome them. As it turns out, multi-perspective modelling is primarily a new methodology, using existing modelling techniques but extending the modelling hierarchy with a new epistemological level which integrates the different perspectives. The methodology will be presented in some detail, and its use will be demonstrated by analyzing an example taken from a socio-political context.Multi Actor SystemsTechnology, Policy and Managemen