Search results for "Lee"
showing 10 items of 1847 documents
Improved SOM Learning using Simulated Annealing
2007
Self-Organizing Map (SOM) algorithm has been extensively used for analysis and classification problems. For this kind of problems, datasets become more and more large and it is necessary to speed up the SOM learning. In this paper we present an application of the Simulated Annealing (SA) procedure to the SOM learning algorithm. The goal of the algorithm is to obtain fast learning and better performance in terms of matching of input data and regularity of the obtained map. An advantage of the proposed technique is that it preserves the simplicity of the basic algorithm. Several tests, carried out on different large datasets, demonstrate the effectiveness of the proposed algorithm in comparis…
Separatrix reconstruction to identify tipping points in an eco-epidemiological model
2018
Many ecological systems exhibit tipping points such that they suddenly shift from one state to another. These shifts can be devastating from an ecological point of view, and additionally have severe implications for the socio-economic system. They can be caused by overcritical perturbations of the state variables such as external shocks, disease emergence, or species removal. It is therefore important to be able to quantify the tipping points. Here we present a study of the tipping points by considering the basins of attraction of the stable equilibrium points. We address the question of finding the tipping points that lie on the separatrix surface, which partitions the space of system traj…
Estimating the decomposition of predictive information in multivariate systems
2015
In the study of complex systems from observed multivariate time series, insight into the evolution of one system may be under investigation, which can be explained by the information storage of the system and the information transfer from other interacting systems. We present a framework for the model-free estimation of information storage and information transfer computed as the terms composing the predictive information about the target of a multivariate dynamical process. The approach tackles the curse of dimensionality employing a nonuniform embedding scheme that selects progressively, among the past components of the multivariate process, only those that contribute most, in terms of co…
Temporal evolution of some mortality indicators: Application to Spanish data
2012
[EN] In Spain, as in other developed countries, significant changes in mortality patterns have occurred during the 20th and 21st centuries. One reflection of these changes is life expectancy, which has improved in this period, although the robustness of this indicator prevents these changes from being of the same order as those for the probability of death. If, moreover, we bear in mind that life expectancy offers no information as to whether this improvement is the same for different age groups, it is important and necessary to turn to other mortality indicators whose past and future evolution in Spain we are going to study. These indicators are applied to Spanish mortality data for the pe…
Modelling residuals dependence in dynamic life tables: A geostatistical approach
2008
The problem of modelling dynamic mortality tables is considered. In this context, the influence of age on data graduation needs to be properly assessed through a dynamic model, as mortality progresses over the years. After detrending the raw data, the residuals dependence structure is analysed, by considering them as a realisation of a homogeneous Gaussian random field defined on R × R. This setting allows for the implementation of geostatistical techniques for the estimation of the dependence and further interpolation in the domain of interest. In particular, a complex form of interaction between age and time is considered, by taking into account a zonally anisotropic component embedded in…
Flexible strategic planning of transport systems
2012
Abstract This paper presents a decision support methodology for long-range planning of transport systems that exhibits strategic flexibility and stochastic system parameters. Unlike one-off strategic decisions, flexible decisions should be dynamically reformulated with time. The proposed methodology is based on the construction of a tree structure of multiple interlinked tactical planning problems, each associated with a scenario in the tree, where problems under scenarios at intermediate dates incorporate in their formulation the solution of the corresponding problems associated with past (future) connected scenarios. The resulting tree structure of interconnected planning decisions become…
Cognitive Deficits in Chronic Stroke Patients: Neuropsychological Assessment, Depression, and Self-Reports
2017
<b><i>Background:</i></b> Following stroke, clinicians are challenged to detect and untangle symptoms of cognitive dysfunction and mood disorders. Additionally, they need to evaluate the informative value of self-reports to identify patients in need of further attendance. <b><i>Aims:</i></b> To examine the association between neuropsychological measures, symptoms of depression, and self-reported cognitive function. <b><i>Methods:</i></b> One-hundred and five chronic stroke patients underwent assessment covering 6 cognitive domains and answered the Hospital Anxiety and Depression Scale and the Memory and Thinking Scale f…
Boosting working memory with accelerated clocks
2021
Our perception of time varies with the degree of cognitive engagement in tasks. The perceived passage of time accelerates while working on demanding tasks, whereas time appears to drag during boring situations. Our experiment aimed at investigating whether this relationship is mutual: Can manipulated announcements of elapsed time systematically affect the attentional resources applied to a cognitive task? We measured behavioral performance and the EEG in a whole report working memory paradigm with six items of different colors that each had to be reported after a short delay period. The 32 participants were informed about the current time after each 20 trials, while the clock was running at…
The success of communication in the Adventures of Joe Fin campaign : self-evaluated effects on health behaviour
2010
Yli puolet suomalaisista liikkuu terveytensä kannalta riittämättömästi. Keski-ikäiset miehet ovat yksi vähiten liikkuvista väestöryhmistä. Kunnossa kaiken ikää -ohjelman SuomiMies seikkailee -kampanja alkoi vuonna 2007, ja sen tavoitteena oli kannustaa keski-ikäisiä miehiä liikkuman enemmän ja syömään terveellisemmin. Kampanja sisälsi liikunta- ja kokkauskursseja, informaatiopitoisen nettisivun, esitteitä sekä 18 Suomen kaupungissa kiertäneen rekkakiertueen. Kiertue sisälsi päivän mittaisia tapahtumia ympäri maata, joiden aikana ihmiset suorittivat terveystestejä, kuuntelivat maalaislääkärin ohjeita ja näkivät humoristista ohjelmaa. Noin 7000 ihmistä testattiin kiertueen aikana. Tämän tutki…
Filamiinin ja pernan tyrosiinikinaasin sitoutuminen sekä vuorovaikutuksen merkitys verihiutaleiden signaloinnissa
2013
Hyytymän muodostuminen tapahtuu verisuoneen kohdistuneen vaurion seurauksena verenvuodon tyrehdyttämiseksi. Hyytymä voi muodostua myös verisuonen pinnalle silloinkin kun verenvuotoa ei esiinny. Irrotessaan verenvuodon mukaan hyytymä voi olla hengenvaarallinen. Erilaiset hyytymän muodostamat veritulpat ovat merkittävä kuolinsyy vuosittain. Verihiutaleet ovat keskeinen tekijä tässä tapahtumassa. Niiden aktivaatio tapahtuu kalvoreseptoreiden ja solun sisäisen signaloinnin monimutkaisesta vuorovaikutuksesta. Tämän tutkimuksen kohteina ovat pernan tyrosiinikinaasi ja filamiini A, joiden välinen vuorovaikutus on tärkeää verihiutaleiden toiminnalle. Verihiutaleet, joissa tämä vuorovaikutus on häir…