| 1. |
- Gerlee, Philip, 1980, et al.
(författare)
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Scientific Models : Red Atoms, White Lies and Black Boxes in a Yellow Book
- 2016
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- A zebrafish, the hull of a miniature ship, a mathematical equation and a food chain - what do these things have in common? They are examples of models used by scientists to isolate and study particular aspects of the world around us. This book begins by introducing the concept of a scientific model from an intuitive perspective, drawing parallels to mental models and artistic representations. It then recounts the history of modelling from the 16th century up until the present day. The iterative process of model building is described and discussed in the context of complex models with high predictive accuracy versus simpler models that provide more of a conceptual understanding. To illustrate the diversity of opinions within the scientific community, we also present the results of an interview study, in which ten scientists from different disciplines describe their views on modelling and how models feature in their work. Lastly, it includes a number of worked examples that span different modelling approaches and techniques. It provides a comprehensive introduction to scientific models and shows how models are constructed and used in modern science. It also addresses the approach to, and the culture surrounding modelling in different scientific disciplines. It serves as an inspiration for model building and also facilitates interdisciplinary collaborations by showing how models are used in different scientific fields. The book is aimed primarily at students in the sciences and engineering, as well as students at teacher training colleges but will also appeal to interested readers wanting to get an overview of scientific modelling in general and different modelling approaches in particular.
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| 2. |
- Gerlee, Philip, 1980, et al.
(författare)
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Scientific Models
- 2016
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- A zebrafish, the hull of a miniature ship, a mathematical equation and a food chain - what do these things have in common? They are examples of models used by scientists to isolate and study particular aspects of the world around us. This book begins by introducing the concept of a scientific model from an intuitive perspective, drawing parallels to mental models and artistic representations. It then recounts the history of modelling from the 16th century up until the present day. The iterative process of model building is described and discussed in the context of complex models with high predictive accuracy versus simpler models that provide more of a conceptual understanding. To illustrate the diversity of opinions within the scientific community, we also present the results of an interview study, in which ten scientists from different disciplines describe their views on modelling and how models feature in their work. Lastly, it includes a number of worked examples that span different modelling approaches and techniques. It provides a comprehensive introduction to scientific models and shows how models are constructed and used in modern science. It also addresses the approach to, and the culture surrounding modelling in different scientific disciplines. It serves as an inspiration for model building and also facilitates interdisciplinary collaborations by showing how models are used in different scientific fields. The book is aimed primarily at students in the sciences and engineering, as well as students at teacher training colleges but will also appeal to interested readers wanting to get an overview of scientific modelling in general and different modelling approaches in particular.
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| 3. |
- Persson, Mats, 1954-, et al.
(författare)
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Risk stratification by guidelines compared to tisk assessment by risk equations applied to a MONICA sample
- 2003
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Ingår i: Journal of Hypertension. - : Lippincott Williams & Wilkins. - 0263-6352 .- 1473-5598. ; 21:6, s. 1089-1095
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Tidskriftsartikel (refereegranskat)abstract
- Background: The World Health Organization/International Society of Hypertension (WHO/ISH) Hypertension Guidelines from 1999 propose a risk stratification scheme for estimating absolute risk for cardiovascular disease (CVD). Risk equations estimated by statistical methods are another way of predicting cardiovascular risk. Objective: We studied the differences between these two approaches when applied to the same set of individuals with high blood pressure. Design and methods: The two northernmost counties in Sweden (NSW) constitute one of the centres in the WHO MONICA (monitoring trends and determinants in cardiovascular disease) Project. Three population surveys have been carried out in 1986, 1990 and 1994, and were used to estimate a risk equation for predicting the 10-year risk of fatal/non-fatal stroke and myocardial infarction. Another MONICA sample from 1999, a total of 5997 subjects, was classified according to the recent WHO/ISH risk stratification scheme. A risk assessment was also performed, by using the risk equations from the NSW MONICA sample and Framingham risk equations. Results: The agreement between the two methods was good when the values obtained from the risk equation were averaged for each risk group obtained from the risk classification by guidelines. However, if the predicted risk for each individual was considered, the agreement was poor for the medium and high-risk groups. Although the average risk for all individuals is the same, many subjects have a higher risk or a lower risk than predicted by guidelines. Conclusions: Risk classification by the 1999 WHO/ISH Hypertension Guidelines is not accurate and detailed enough for medium- and high-risk patients, which could be of clinical importance in the medium risk group.
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| 4. |
- Otani, Hiroki, et al.
(författare)
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Morphometric study on the characteristic external features of normal and abnormal human embryos
- 2008
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Ingår i: Congenit Anom Kyoto. - : Wiley. ; 48:1, s. 18-28
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Tidskriftsartikel (refereegranskat)abstract
- The embryonic period is characterized by organogenesis and accompanying dynamic changes in external features. The measurement of human embryos has been limited to whole body dimensions, such as crown-rump length. More detailed measurements would add quantitative information about these characteristic events and provide a better understanding of normal and abnormal embryonic development. In the present study, we defined axes, landmarks, and measurements for human embryos, and measured 250 externally normal human embryos at Carnegie stages 14-23 (6.5-29.3 mm in crown-rump length, approximately 5-8 weeks of estimated ovulation age) that were fixed in Bouin's solution and preserved in 10% formalin solution. The axes, landmarks, and measurements defined for human embryos are corresponding to those in human and primate fetuses. The whole body, head, face, and extremities were measured using a scale attached to a dissecting microscope. Axial length, head height plus ear-shoulder length plus trunk height, was designated as a new measurement of the whole body, which is comparable with crown-rump length. Approximate standards of these measurements were obtained. The ratios of some measurements to trunk height and between the different parts were also obtained, and several different developmental patterns were recognized. The reproducibility of each measurement was evaluated by measuring 50 specimens three times each at intervals of one or two months. As a pilot study for the application of the proposed measurements, 84 human embryos with external anomalies, including holoprosencephaly, anomalies of extremities, and pharyngeal arch anomalies, were measured using the same method, and a few tendencies characteristic to holoprosencephaly were noticed.
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| 5. |
- Tamagawa, T., et al.
(författare)
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Correlation between musculoskeletal structure of the hand and primate locomotion: Morphometric and mechanical analysis in prehension using the cross- and triple-ratios
- 2020
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 15:5
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Tidskriftsartikel (refereegranskat)abstract
- Biometric ratios of the relative length of the rays in the hand have been analyzed between primate species in the light of their hand function or phylogeny. However, how relative lengths among phalanges are mechanically linked to the grasping function of primates with different locomotor behaviors remains unclear. To clarify this, we calculated cross and triple-ratios, which are related to the torque distribution, and the torque generation mode at different joint angles using the lengths of the phalanges and metacarpal bones in 52 primates belonging to 25 species. The torque exerted on the finger joint and traction force of the flexor tendons necessary for a cylindrical grip and a suspensory hand posture were calculated using the moment arm of flexor tendons measured on magnetic resonance images, and were compared among Hylobates spp., Ateles sp., and Papio hamadryas. Finally, the torques calculated from the model were validated by a mechanical study detecting the force exerted on the phalanx by pulling the digital flexor muscles during suspension in these three species. Canonical discriminant analysis of cross and triple-ratios classified primates almost in accordance with their current classification based on locomotor behavior. The traction force was markedly reduced with flexion of the MCP joint parallel to the torque in brachiating primates; this was notably lower in the terrestrial quadrupedal primates than in the arboreal primates at mild flexion. Our mechanical study supported these features in the torque and traction force generation efficiencies. Our results suggest that suspensory or terrestrial quadrupedal primates have hand structures that can exert more torque at a suspensory posture, or palmigrade and digitigrade locomotion, respectively. Furthermore, our study suggests availability of the cross and triple-ratios as one of the indicators to estimate the hand function from the skeletal structure.
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| 6. |
- Berbyuk, Viktor, 1953
(författare)
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Dynamics and optimal control of biotechnical systems "Man-Prosthesis"
- 1997
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Ingår i: IUTAM Symposium on Interaction Between Dynamics and Control in Advanced Mechanical Systems, Ed. D. van Campen, Kluwer Academic Publishers, 1997. - Dordrecht : Springer Netherlands. ; , s. 35-42
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Konferensbidrag (refereegranskat)abstract
- In the paper, a mathematical model is proposed for investigating the controlled motion of human locomotion system (HLS) with an above-knee prosthesis. To provide insight into the interaction between dynamics and control in biotechnical system Man-Prosthesis the energy optimal control problem of the HLS wearing a lower limb prosthesis has been considered. The algorithm is based on special conversion of the optimal control problem for a nonlinear dynamical system which models HLS into a standard nonlinear programming problem. A number of energy-optimal control problems of human locomotion with an artificial leg, and optimization problems for the constructive parameters of the prostheses under different boundary conditions and constraints have been solved. The numerical results obtained were compared with experimental data for normal human locomotion. The energy-optimal elastic and viscoelastic characteristics of the ankle and knee joints of the prostheses have been determined.
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| 7. |
- Mamontov, Eugen, 1955
(författare)
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Modelling homeorhesis by ordinary differential equations
- 2007
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Ingår i: Mathl Comput. Modelling. - : Elsevier BV. - 0895-7177. ; 45:5-6, s. 694-707
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Tidskriftsartikel (refereegranskat)abstract
- Homeorhesis is a necessary feature of any living system. If a system does not perform homeorhesis, it is nonliving. The present work develops the sufficient conditions for the ODE model to describe homeorhesis and suggests the structure of the model. The proposed homeorhesis model is fairly general. It treats homeorhesis as piecewise homeostasis. The model can be specified in different ways depending on the specific system and specific purposes of this analysis. An example of the specification is the PhasTraM model, the homeorhesis-aware nonlinear reaction–diffusion model for hyperplastic oncogeny in the previous works of the author. The qualitative agreement of the developed homeorhesis model with the living-system experimental results is noted. The work also shows that the basic mathematical models (such as the active-particle generalized kinetic theory) are substantially more important for the living-matter studies than in the case of nonliving matter. A few directions for future research are suggested as well.
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| 8. |
- Almqvist, Joachim E, 1980, et al.
(författare)
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A Kinetic Model of the Monocarboxylate Transporter MCT1 and its Interaction with Carbonic Anhydrase II
- 2010
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Ingår i: Journal of Computer Science and Systems Biology. - : OMICS Publishing Group. - 0974-7230. ; 3:5, s. 107-116
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Tidskriftsartikel (refereegranskat)abstract
- The enzyme carbonic anhydrase isoform II (CAII), catalyzing the hydration and dehy-dration of CO2, enhances transport activity of the monocarboxylate transporter isoform I (MCT1, SLC16A1) expressed in Xenopus oocytes by a mechanism that does not require CAII catalytic activity. In the present study, we have investigated the mechanism of the CAII induced increase in transport activity by using electrophysiological techniques and mathematical modeling of the MCT1 transport cycle. The model consists of six states arranged in cyclic fashion and features an ordered, mirrorsymmetric, binding mechanism, where binding and unbinding of the proton to the transport protein is considered to be the rate limiting step under physiological conditions. An explicit rate expression for the substrate flux is derived using model reduction techniques. By treating the pools of intra-and extracellular MCT1 substrates as dynamic states, the time dependent kinetics are obtained by integration, using the derived expression for the substrate flux. The simulations were compared with experimental data obtained from MCT1-expressing oocytes injected with different amounts of CAII. The model suggests that CAII increases the effective rate constants of the proton reactions, possibly by working as a proton antenna.
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| 9. |
- Enam, Amia, et al.
(författare)
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Evidence based evaluation of eHealth interventions: A systematic literature review
- 2018
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Ingår i: Journal of Medical Internet Research. - : JMIR Publications Inc.. - 1438-8871. ; 20:11
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Forskningsöversikt (refereegranskat)abstract
- Background: Until now, the use of technology in health care was driven mostly by the assumptions about the benefits of electronic health (eHealth) rather than its evidence. It is noticeable that the magnitude of evidence of effectiveness and efficiency of eHealth is not proportionate to the number of interventions that are regularly conducted. Reliable evidence generated through comprehensive evaluation of eHealth interventions may accelerate the growth of eHealth for long-term successful implementation and help to experience eHealth benefits in an enhanced way. Objective: This study aimed to understand how the evidence of effectiveness and efficiency of eHealth can be generated through evaluation. Hence, we aim to discern (1) how evaluation is conducted in distinct eHealth intervention phases, (2) the aspects of effectiveness and efficiency that are typically evaluated during eHealth interventions, and (3) how eHealth interventions are evaluated in practice. Methods: A systematic literature review was conducted to explore the evaluation methods for eHealth interventions. Preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed. We searched Google Scholar and Scopus for the published papers that addressed the evaluation of eHealth or described an eHealth intervention study. A qualitative analysis of the selected papers was conducted in several steps. Results: We intended to see how the process of evaluation unfolds in distinct phases of an eHealth intervention. We revealed that in practice and in several conceptual papers, evaluation is performed at the end of the intervention. There are some studies that discuss the importance of conducting evaluation throughout the intervention; however, in practice, we found no case study that followed this. For our second research question, we discovered aspects of efficiency and effectiveness that are proposed to be assessed during interventions. The aspects that were recurrent in the conceptual papers include clinical, human and social, organizational, technological, cost, ethical and legal, and transferability. However, the case studies reviewed only evaluate the clinical and human and social aspects. At the end of the paper, we discussed a novel approach to look into the evaluation. Our intention was to stir up a discussion around this approach with the hope that it might be able to gather evidence in a comprehensive and credible way. Conclusions: The importance of evidence in eHealth has not been discussed as rigorously as have the diverse evaluation approaches and evaluation frameworks. Further research directed toward evidence-based evaluation can not only improve the quality of intervention studies but also facilitate successful long-term implementation of eHealth in general. We conclude that the development of more robust and comprehensive evaluation of eHealth studies or an improved validation of evaluation methods could ease the transferability of results among similar studies. Thus, the resources can be used for supplementary research in eHealth.
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| 10. |
- Gosman-Hedström, Gunilla, 1947, et al.
(författare)
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Parallel reliability of the functional independence measure and the Barthel ADL index.
- 2000
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Ingår i: Disability and rehabilitation. - 0963-8288. ; 22:16, s. 702-15
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of this study was to evaluate the concordance between the assessments of ADL according to the Functional Independence Measure (FIM) and the Barthel ADL index (BI) by means of a rank-invariant statistical method. METHOD: The construct validity, also called parallel reliability, of FIM and BI was assessed on the item level. Two different approaches to condensing the FIM assessments into 2-4 scale steps on the item level in order to calibrate the two ADL instruments were compared. One was determined by the theoretical operational definitions and the other defined by the empirical definitions. The 204 assessments of elderly persons were made three months after stroke by means of interviews. RESULTS: The parallel reliability of the FIM and the BI on the item level was strong, both according to the theoretical cut-off levels defined by the operational definitions and the empirical cut-off levels defined by the marginal distributions. CONCLUSIONS: The concordance between FIM and BI was high. There was a slight difference in favour of the operational definitions. The clinical key elements are to have a critical attitude towards ADL instruments; how they are constructed and operationalized. These are important elements in the quality assurance in the everyday work.
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