Tourists’ landscape perceptions and preferences in a Scandinavian coastal region

European cultural landscapes have been subject to change since the middle of the twentieth century, and among the most significant alterations are general re-growth, reforestation, and overgrowth. Such changes might lead to landscape loss for locals and deterioration of vistas for sightseeing holidaymakers. This article responds to a lack of academic research on landscape perceptions among tourists. The main objective is to explore international tourists’ landscape perceptions in a coastal area in northern Scandinavia, focusing on three different concepts thought to be important for tourists’ landscape preferences: typicality, vegetation lushness, and degree of human influence. A combination of free and directed sorting procedures was employed. Quantitative and categorical data derived from the multiple sorting methods were subjected to multidimensional scaling analysis. The results indicate that foreign tourists might have an understanding of re-growth in the case area. Preference ratings gave mixed results in relation to vegetation and human influence as important features for landscape preferences, as found in previous studies. The findings emphasise the need for taking into consideration typicality of setting in future landscape research.     

Modeling the electrical activity of the heart: A Bidomain Model of the ventricles embedded in a torso

In this paper a model for the electrical activity of the heart will be presented and an approach to solve the resulting numerical problem will be suggested. The Bidomain Model is used to compute the spatial distribution of the electrical potential. The partial differential equations are discretized with the finite element method and the multigrid method is used to solve the corresponding linear equations. Adaptivity is applied to resolve the steep gradients in the solution. Received: 24 January 2000 / Accepted: 29 June 2002 / Published online: 10 April 2003 Communicated by G. Wittum     

Unstable eigenmodes are possible drivers for cardiac arrhythmias

The well-organized contraction of each heartbeat is enabled by an electrical wave traversing and exciting the myocardium in a regular manner. Perturbations to this wave, referred to as arrhythmias, can lead to lethal fibrillation if not treated within minutes. One manner in which arrhythmias originate is an ill-fated interaction of the regular electrical signal controlling the heartbeat, the sinus wave, with an ectopic stimulus. It is not fully understood how and when ectopic waves are generated. Based on mathematical models, we show that ectopic beats can be characterized in terms of unstable eigenmodes of the resting state.     

Requirements in the medical domain: Experiences and prescriptions

Research shows that information flow in health care systems is inefficient and prone to error. Data is lost, and physicians must repeat tests and examinations because the results are unavailable at the right place and time. Cases of erroneous medication - resulting from misinterpreted, misunderstood, or missing information - are well known and have caused serious health problems and even death. We strongly believe that through effective use of information technology, we can improve both the quality and efficiency of the health sector's work. Introducing a new system might shift power from old to young, from doctor to nurse, or from medical staff to administration. Few people appreciate loss of power, but even fewer will admit that the loss of power is why they resist the new system. Thus, we must work hard to bring this into the open and help people realize that a new system doesn't have to threaten their positions. Again, knowledge and understanding of a hospital's organizational structure, both official and hidden, is necessary if the system's introduction is to be successful.     

Noise, sleep and poor health: Modeling the relationship between road traffic noise and cardiovascular problems

Several adverse effects have been associated with exposure to traffic noise. Studies supporting a noise-stress-health model have suggested links between noise level and increased noradrenalin concentrations in urine, hypertension and myocardial infarction. Among the more commonly documented effects, sleep disturbances have been regarded as being the most serious. Both noise annoyance and sleep disturbance have been proposed as important mediators of the impact of noise on health. The present paper investigates the relationships among long-term noise exposure, annoyance, sleeping problems and subjective health complaints by the use of a structural equation model. Further, it aims at giving insight into how noise sensitivity is related to sleep disturbances from road traffic noise. Finally, it examines whether any effect of noise exposure or response to noise can be detected on prevalence of cardiovascular problems, when information on sleep disturbances is included in a model. Data from a questionnaire survey conducted among a population sample in Oslo (N = 2786) are combined with nighttime noise levels calculated from outside each respondents dwelling, at the bedroom façade. The results of the analysis showed significant relationships between noise annoyance at night and sleeping problems. The model also showed strong links among pseudoneurological complaints, annoyance and sleeping problems, thus pointing to the importance of including information on psychosomatic disorders and mild psychological problems in future studies looking at potential health effects of noise. The analysis showed no relationship between neither noise exposure nor response to noise and cardiovascular problems.     

Computing the size and location of myocardial ischemia using measurements of ST-segment shift

It is well known that the presence of myocardial ischemia can be observed as a shift in the ST segment of an electrocardiogram (ECG) recording. The question we address in this paper is whether or not ST shift can be used to compute approximations of the size and location of the ischemic region. We begin by investigating a cost functional (measuring the difference between synthetic recorded data and simulated values of ST shift) for a parameter identification problem to locate the ischemic region. We then formulate a more flexible representation of the ischemia using a level set framework and solve the associated minimization problem for the size and position of the ischemia. We apply this framework to a set of ECG data generated by the Bidomain model using the cell model of Winslow et al. Based on this data, we show that values of ST shift recorded at the body surface are capable of identifying the position and (roughly) the size of the ischemia.     

Laboratory scale simulation of three-way catalyst engine ageing

In this work, a laboratory ageing cycle simulating the real engine ageing for three-way catalysts was developed. The laboratory cycle was created based on the rapid ageing hot (RAH) cycle used in the engine bench ageings. The simultaneous gas concentration and temperature changes were achieved by adjusting the IR-furnace and the gas flow parameters. The laboratory ageing cycle was verified by testing different samples after different ageings with the laboratory and the engine tests. In addition, some characterization methods: specific surface area (BET-method), dispersion (CO-chemisorption), particle size (CO-chemisorption) and oxygen storage capacity (with CO–O₂ exchange experiments), were used to compare the effect of the different ageings on the catalyst samples.     

A Second-Order Algorithm for Solving Dynamic Cell Membrane Equations

This paper describes an extension of the so-called Rush-Larsen scheme, which is a widely used numerical method for solving dynamic models of cardiac cell electrophysiology. The proposed method applies a local linearization of nonlinear terms in combination with the analytical solution of linear ordinary differential equations to obtain a second-order accurate numerical scheme. We compare the error and computational load of the second-order scheme to the original Rush-Larsen method and a second-order Runge-Kutta (RK) method. The numerical results indicate that the new method outperforms the original Rush-Larsen scheme for all the test cases. The comparison with the RK solver reveals that the new method is more efficient for stiff problems.     

Mathematical models and numerical methods for the forward problem in cardiac electrophysiology

The purpose of this article is to give an overview of the forward problem of cardiac electrophysiology. The relevant models are derived and the mathematical problem formulated. Different solution strategies are discussed. In particular, the error introduced by solving the equations decoupled is demonstrated. Some novel techniques to deal with this problem are presented. Received: 21 December 2000 / Accepted: 29 June 2002 / Published online: 10 April 2003 Communicated by G. Wittum