944 resultados para textual complexity analysis
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Kulttuuriset ja tekstuaaliset tekijät alluusioiden kääntämisessä ja tulkinnassa. Alluusiot Dorothy L. Sayersin 1940- ja 1980-luvuilla suomennetuissa salapoliisiromaaneissa Väitöskirja käsittelee alluusioiden kääntämistä ja tulkintaa. Alluusio on intertekstuaalinen viittaus, jonka tulkitsemiseen tarvitaan implisiittistä tietoa tutuksi oletetusta viittauskohteesta. Käännösongelma alluusiosta tulee, mikäli kohdekulttuurin lukijat eivät tunne viittauskohdetta eivätkä voi päätellä alluusion merkitystä. Tutkimus pyrkii kuitenkin uuden analyysimenetelmän avulla osoittamaan, että vieraat alluusiot eivät välttämättä johda tulkintaongelmiin. Väitöskirja jakautuu kahteen osaan: analyysimenetelmän kehittämiseen (luvut 1-5) sekä tapaustutkimukseen (luvut 6-7). Kehitetyn menetelmän avulla pystytään analysoimaan aikaisempaa tarkemmin, millaisia tulkintamahdollisuuksia alluusiot tarjoavat eri lukijakunnille ja miten lähdetekstin alluusioiden kulttuuriset ja tekstuaaliset piirteet korreloivat käännösstrategioiden kanssa. Tapaustutkimus selvittää, millaisia tulkintamahdollisuuksia Dorothy L. Sayersin 1940- ja 1980-luvuilla suomennettujen salapoliisiromaanien alluusiot tarjosivat aikansa suomalaisille lukijoille. Tavoitteena on myös hahmottaa, miten suomentajien käännösratkaisut ja alluusioiden tulkintamahdollisuudet liittyvät toisaalta lähdetekstin alluusioiden piirteisiin ja toisaalta kohdekulttuurin kontekstiin. Tapaustutkimus tarjoaa näin uutta tietoa suomennoskirjallisuuden ja salapoliisiromaanien historiasta. Analyysimenetelmä määrittelee aikaisempaa alluusioita ja intertekstuaalisuutta käsitelleen tutkimuksen pohjalta ne kulttuuriset ja tekstuaaliset piirteet, jotka vaikuttavat alluusioiden kääntämiseen ja tulkintaan. Kulttuurisessa mielessä alluusio voi olla tietylle lukijakunnalle tuttu tai tuntematon. Tekstuaalisia tekijöitä ovat alluusion muodon ja tyylin tunnusmerkillisyys sekä alluusion pintamerkityksen koherenttius uudessa tekstikontekstissa, ilman tietoa viittauskohteesta. Alluusioiden tulkinnassa on perinteisesti erotettu toisaalta allusiivinen tulkintamahdollisuus, jossa alluusio on lukijoille tuttu ja yhdistettävissä viittauskohteeseensa, toisaalta kulttuuritöyssy, jonka muodostaa lukijoille tuntematon ja pintamerkitykseltään inkoherentti alluusio. Tutkimuksessa määritellään kulttuuristen ja tekstuaalisten tekijöiden perusteella lisäksi kaksi muuta mahdollisuutta. Pseudo-allusiivisessa tulkinnassa tuntematon alluusio erottuu ympäröivästä tekstikontekstista tyyliltään ja on koherentti ainakin kuvaannollisessa mielessä ilman viittauskohdettaan. Ei-allusiivisessa tulkinnassa taas vieras alluusio sulautuu kontekstiin sekä muodoltaan että merkitykseltään niin, ettei lukija edes huomaa mahdollista alluusiota. Tulkintamahdollisuuksien jakauma antaa yleiskuvan siitä, miten tietty lukijakunta pystyi tulkitsemaan tekstin alluusioita. Lisäksi analyysi tarkastelee lähdetekstin ja käännöksen välillä tulkintamahdollisuuksissa tapahtuneita muutoksia sekä niiden vaikutusta tulkinnan vaatimaan vaivannäköön (effort) ja alluusion funktioihin. Tapaustutkimus perehtyy Sayers-suomennosten kulttuurikonteksteihin tarkastelemalla salapoliisiromaanien asemaa suomalaisessa kirjallisuusjärjestelmässä, suomennoksilta odotettuja piirteitä sekä suomentajien ammattikuvaa, taustoja ja työoloja. Tulosten perusteella alluusioiden kääntäminen oli vaativa tehtävä sekä 1940- että 1980-luvun suomentajille. Lähdetekstien alluusioista 60–70 prosenttia oli todennäköisesti kohdelukijoille vieraita. Molempina aikakausina suomennoksilta odotettiin silti sekä kielellistä sujuvuutta että lähdetekstin merkitysten välittämistä. 1940-luvun suomentajien tehtävää vaikeutti lisäksi mm. se, että suomentaminen oli enimmäkseen sivutoimista ja englanti oli harvoin parhaiten hallittu vieras kieli. Nämä olosuhteet lienevät vaikuttaneet etenkin vähäarvoisena pidetyn salapoliisikirjallisuuden suomennoksiin. 1980-luvulla suomentajien aikataulut olivat realistisempia, englannin taidot parempia ja päätoiminen suomentaminen mahdollista. Myös salapoliisiromaanien arvostus oli lisääntynyt. Sekä 1940- että 1980-luvun suomennoksissa kohdelukijoille vieraitakin alluusioita oli usein säilytetty, mikäli ne olivat koherentteja ilman viittauskohdettaan. Sen sijaan vieraita ja pintamerkitykseltään epäselviä alluusioita oli muokattu tai poistettu. Kuitenkin 1980-luvun suomentajat säilyttivät lähdetekstin alluusioita useammin ja tarkemmin kuin 1940-luvun suomentajat. Varsinkin poisjättämistä esiintyi 1940-luvun suomennoksissa enemmän. Alluusioiden tulkintamahdollisuudet olivat kaikissa käännöksissä muuttuneet sikäli, että melko harvat suomennetut alluusiot olivat enää kohdelukijoiden tunnistettavissa. Toisaalta myös kulttuuritöyssyt olivat harvinaisia. Erot 1940- ja 1980-luvun suomennosten välillä näkyivätkin pseudo-allusiivisissa ja ei-allusiivisissa tulkintamahdollisuuksissa. 1980-luvun suomennoksissa vieraat alluusiot oli johdonmukaisesti säilytetty niin, että käännetyt alluusiot voitiin tulkita pseudo-alluusioiksi. Sen sijaan 1940-luvun suomennoksissa vieraita alluusioita oli usein muokattu tai jätetty pois tavalla, joka johti ei-allusiiviseen tulkintaan. Kohdelukijoiden kannalta 1980-luvun suomennettujen alluusioiden tulkitseminen lienee vaatinut jonkin verran enemmän vaivaa. Toisaalta pseudo-allusiivisten käännösten pohjalta oli useimmiten mahdollista rakentaa koherentti tulkinta, ja monesti ne jopa välittivät samankaltaisia funktioita kuin lähdetekstin alluusiot. 1940-luvun suomennosten muokkaukset ja poistot periaatteessa helpottivat tulkintaa, mutta mahdollisia kulttuuritöyssyjä esiintyi edelleen, jopa kääntäjän tekemien muutosten seurauksena. 1940-luvun suomennoksissa myös käännettyjen alluusioiden funktiot olivat muuttuneet enemmän lähdetekstin alluusioihin nähden. Kaiken kaikkiaan 1980-luvun suomennokset olivat lähempänä oman aikansa hyvän käännöksen piirteitä. Toisaalta alluusioiden muokkaaminen sai 1940-luvun suomennokset muistuttamaan enemmän perinteistä arvoituksen ratkaisuun keskittyvää salapoliisiromaania, joten tältä osin ne lienevät vastanneet kohdelukijoiden odotuksia. Kulttuurikontekstin vaikutus siis näkyi sekä käännösstrategioissa että käännettyjen alluusioiden tulkintamahdollisuuksissa. Tutkimustuloksissa korostui kuitenkin myös se, että lähdetekstin alluusion pintamerkitys saattaa vaikuttaa käännösratkaisuihin. Lisäksi käännetyt pseudo-alluusiot saattavat välittää samankaltaisia funktioita kuin lähdetekstin alluusiot. Toisin kuin yleensä on esitetty, kohdelukijoille vieraiden alluusioiden säilyttäminen saattaakin siis olla toimiva ratkaisu.
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Class exercise to analyse qualitative data mediated on use of a set of transcripts, augmented by videos from web site. Discussion is around not only how the data is codes, interview bias, dimensions of analysis. Designed as an introduction.
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Complexity in time series is an intriguing feature of living dynamical systems, with potential use for identification of system state. Although various methods have been proposed for measuring physiologic complexity, uncorrelated time series are often assigned high values of complexity, errouneously classifying them as a complex physiological signals. Here, we propose and discuss a method for complex system analysis based on generalized statistical formalism and surrogate time series. Sample entropy (SampEn) was rewritten inspired in Tsallis generalized entropy, as function of q parameter (qSampEn). qSDiff curves were calculated, which consist of differences between original and surrogate series qSampEn. We evaluated qSDiff for 125 real heart rate variability (HRV) dynamics, divided into groups of 70 healthy, 44 congestive heart failure (CHF), and 11 atrial fibrillation (AF) subjects, and for simulated series of stochastic and chaotic process. The evaluations showed that, for nonperiodic signals, qSDiff curves have a maximum point (qSDiff(max)) for q not equal 1. Values of q where the maximum point occurs and where qSDiff is zero were also evaluated. Only qSDiff(max) values were capable of distinguish HRV groups (p-values 5.10 x 10(-3); 1.11 x 10(-7), and 5.50 x 10(-7) for healthy vs. CHF, healthy vs. AF, and CHF vs. AF, respectively), consistently with the concept of physiologic complexity, and suggests a potential use for chaotic system analysis. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4758815]
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Background: In normal aging, the decrease in the syntactic complexity of written production is usually associated with cognitive deficits. This study was aimed to analyze the quality of older adults' textual production indicated by verbal fluency (number of words) and grammatical complexity (number of ideas) in relation to gender, age, schooling, and cognitive status. Methods: From a probabilistic sample of community-dwelling people aged 65 years and above (n = 900), 577 were selected on basis of their responses to the Mini-Mental State Examination (MMSE) sentence writing, which were submitted to content analysis; 323 were excluded as they left the item blank or performed illegible or not meaningful responses. Education adjusted cut-off scores for the MMSE were used to classify the participants as cognitively impaired or unimpaired. Total and subdomain MMSE scores were computed. Results: 40.56% of participants whose answers to the MMSE sentence were excluded from the analyses had cognitive impairment compared to 13.86% among those whose answers were included. The excluded participants were older and less educated. Women and those older than 80 years had the lowest scores in the MMSE. There was no statistically significant relationship between gender, age, schooling, and textual performance. There was a modest but significant correlation between number of words written and the scores in the Language subdomain. Conclusions: Results suggest the strong influence of schooling and age over MMSE sentence performance. Failing to write a sentence may suggest cognitive impairment, yet, instructions for the MMSE sentence, i.e. to produce a simple sentence, may limit its clinical interpretation.
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This Doctoral Thesis unfolds into a collection of three distinct papers that share an interest in institutional theory and technology transfer. Taking into account that organizations are increasingly exposed to a multiplicity of demands and pressures, we aim to analyze what renders this situation of institutional complexity more or less difficult to manage for organizations, and what makes organizations more or less successful in responding to it. The three studies offer a novel contribution both theoretically and empirically. In particular, the first paper “The dimensions of organizational fields for understanding institutional complexity: A theoretical framework” is a theoretical contribution that tries to better understand the relationship between institutional complexity and fields by providing a framework. The second article “Beyond institutional complexity: The case of different organizational successes in confronting multiple institutional logics” is an empirical study which aims to explore the strategies that allow organizations facing multiple logics to respond more successfully to them. The third work “ How external support may mitigate the barriers to university-industry collaboration” is oriented towards practitioners and presents a case study about technology transfer in Italy.
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L'applicazione di misure, derivanti dalla teoria dell'informazione, fornisce un valido strumento per quantificare alcune delle proprietà dei sistemi complessi. Le stesse misure possono essere utilizzate in robotica per favorire l'analisi e la sintesi di sistemi di controllo per robot. In questa tesi si è analizzata la correlazione tra alcune misure di complessità e la capacità dei robot di portare a termine, con successo, tre differenti task. I risultati ottenuti suggeriscono che tali misure di complessità rappresentano uno strumento promettente anche nel campo della robotica, ma che il loro utilizzo può diventare difficoltoso quando applicate a task compositi.
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Research and professional practices have the joint aim of re-structuring the preconceived notions of reality. They both want to gain the understanding about social reality. Social workers use their professional competence in order to grasp the reality of their clients, while researchers’ pursuit is to open the secrecies of the research material. Development and research are now so intertwined and inherent in almost all professional practices that making distinctions between practising, developing and researching has become difficult and in many aspects irrelevant. Moving towards research-based practices is possible and it is easily applied within the framework of the qualitative research approach (Dominelli 2005, 235; Humphries 2005, 280). Social work can be understood as acts and speech acts crisscrossing between social workers and clients. When trying to catch the verbal and non-verbal hints of each others’ behaviour, the actors have to do a lot of interpretations in a more or less uncertain mental landscape. Our point of departure is the idea that the study of social work practices requires tools which effectively reveal the internal complexity of social work (see, for example, Adams & Dominelli & Payne 2005, 294 – 295). The boom of qualitative research methodologies in recent decades is associated with much profound the rupture in humanities, which is called the linguistic turn (Rorty 1967). The idea that language is not transparently mediating our perceptions and thoughts about reality, but on the contrary it constitutes it was new and even confusing to many social scientists. Nowadays we have got used to read research reports which have applied different branches of discursive analyses or narratologic or semiotic approaches. Although differences are sophisticated between those orientations they share the idea of the predominance of language. Despite the lively research work of today’s social work and the research-minded atmosphere of social work practice, semiotics has rarely applied in social work research. However, social work as a communicative practice concerns symbols, metaphors and all kinds of the representative structures of language. Those items are at the core of semiotics, the science of signs, and the science which examines people using signs in their mutual interaction and their endeavours to make the sense of the world they live in, their semiosis. When thinking of the practice of social work and doing the research of it, a number of interpretational levels ought to be passed before reaching the research phase in social work. First of all, social workers have to interpret their clients’ situations, which will be recorded in the files. In some very rare cases those past situations will be reflected in discussions or perhaps interviews or put under the scrutiny of some researcher in the future. Each and every new observation adds its own flavour to the mixture of meanings. Social workers have combined their observations with previous experience and professional knowledge, furthermore, the situation on hand also influences the reactions. In addition, the interpretations made by social workers over the course of their daily working routines are never limited to being part of the personal process of the social worker, but are also always inherently cultural. The work aiming at social change is defined by the presence of an initial situation, a specific goal, and the means and ways of achieving it, which are – or which should be – agreed upon by the social worker and the client in situation which is unique and at the same time socially-driven. Because of the inherent plot-based nature of social work, the practices related to it can be analysed as stories (see Dominelli 2005, 234), given, of course, that they are signifying and told by someone. The research of the practices is concentrating on impressions, perceptions, judgements, accounts, documents etc. All these multifarious elements can be scrutinized as textual corpora, but not whatever textual material. In semiotic analysis, the material studied is characterised as verbal or textual and loaded with meanings. We present a contribution of research methodology, semiotic analysis, which has to our mind at least implicitly references to the social work practices. Our examples of semiotic interpretation have been picked up from our dissertations (Laine 2005; Saurama 2002). The data are official documents from the archives of a child welfare agency and transcriptions of the interviews of shelter employees. These data can be defined as stories told by the social workers of what they have seen and felt. The official documents present only fragmentations and they are often written in passive form. (Saurama 2002, 70.) The interviews carried out in the shelters can be described as stories where the narrators are more familiar and known. The material is characterised by the interaction between the interviewer and interviewee. The levels of the story and the telling of the story become apparent when interviews or documents are examined with the use of semiotic tools. The roots of semiotic interpretation can be found in three different branches; the American pragmatism, Saussurean linguistics in Paris and the so called formalism in Moscow and Tartu; however in this paper we are engaged with the so called Parisian School of semiology which prominent figure was A. J. Greimas. The Finnish sociologists Pekka Sulkunen and Jukka Törrönen (1997a; 1997b) have further developed the ideas of Greimas in their studies on socio-semiotics, and we lean on their ideas. In semiotics social reality is conceived as a relationship between subjects, observations, and interpretations and it is seen mediated by natural language which is the most common sign system among human beings (Mounin 1985; de Saussure 2006; Sebeok 1986). Signification is an act of associating an abstract context (signified) to some physical instrument (signifier). These two elements together form the basic concept, the “sign”, which never constitutes any kind of meaning alone. The meaning will be comprised in a distinction process where signs are being related to other signs. In this chain of signs, the meaning becomes diverged from reality. (Greimas 1980, 28; Potter 1996, 70; de Saussure 2006, 46-48.) One interpretative tool is to think of speech as a surface under which deep structures – i.e. values and norms – exist (Greimas & Courtes 1982; Greimas 1987). To our mind semiotics is very much about playing with two different levels of text: the syntagmatic surface which is more or less faithful to the grammar, and the paradigmatic, semantic structure of values and norms hidden in the deeper meanings of interpretations. Semiotic analysis deals precisely with the level of meaning which exists under the surface, but the only way to reach those meanings is through the textual level, the written or spoken text. That is why the tools are needed. In our studies, we have used the semiotic square and the actant analysis. The former is based on the distinctions and the categorisations of meanings, and the latter on opening the plotting of narratives in order to reach the value structures.
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CONTEXT The necessity of specific intervention components for the successful treatment of patients with posttraumatic stress disorder is the subject of controversy. OBJECTIVE To investigate the complexity of clinical problems as a moderator of relative effects between specific and nonspecific psychological interventions. METHODS We included 18 randomized controlled trials, directly comparing specific and nonspecific psychological interventions. We conducted moderator analyses, including the complexity of clinical problems as predictor. RESULTS Our results have confirmed the moderate superiority of specific over nonspecific psychological interventions; however, the superiority was small in studies with complex clinical problems and large in studies with noncomplex clinical problems. CONCLUSIONS For patients with complex clinical problems, our results suggest that particular nonspecific psychological interventions may be offered as an alternative to specific psychological interventions. In contrast, for patients with noncomplex clinical problems, specific psychological interventions are the best treatment option.
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OBJECTIVES The purpose of this study was to compare the 2-year safety and effectiveness of new- versus early-generation drug-eluting stents (DES) according to the severity of coronary artery disease (CAD) as assessed by the SYNTAX (Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery) score. BACKGROUND New-generation DES are considered the standard-of-care in patients with CAD undergoing percutaneous coronary intervention. However, there are few data investigating the effects of new- over early-generation DES according to the anatomic complexity of CAD. METHODS Patient-level data from 4 contemporary, all-comers trials were pooled. The primary device-oriented clinical endpoint was the composite of cardiac death, myocardial infarction, or ischemia-driven target-lesion revascularization (TLR). The principal effectiveness and safety endpoints were TLR and definite stent thrombosis (ST), respectively. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated at 2 years for overall comparisons, as well as stratified for patients with lower (SYNTAX score ≤11) and higher complexity (SYNTAX score >11). RESULTS A total of 6,081 patients were included in the study. New-generation DES (n = 4,554) compared with early-generation DES (n = 1,527) reduced the primary endpoint (HR: 0.75 [95% CI: 0.63 to 0.89]; p = 0.001) without interaction (p = 0.219) between patients with lower (HR: 0.86 [95% CI: 0.64 to 1.16]; p = 0.322) versus higher CAD complexity (HR: 0.68 [95% CI: 0.54 to 0.85]; p = 0.001). In patients with SYNTAX score >11, new-generation DES significantly reduced TLR (HR: 0.36 [95% CI: 0.26 to 0.51]; p < 0.001) and definite ST (HR: 0.28 [95% CI: 0.15 to 0.55]; p < 0.001) to a greater extent than in the low-complexity group (TLR pint = 0.059; ST pint = 0.013). New-generation DES decreased the risk of cardiac mortality in patients with SYNTAX score >11 (HR: 0.45 [95% CI: 0.27 to 0.76]; p = 0.003) but not in patients with SYNTAX score ≤11 (pint = 0.042). CONCLUSIONS New-generation DES improve clinical outcomes compared with early-generation DES, with a greater safety and effectiveness in patients with SYNTAX score >11.
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BACKGROUND Diabetes mellitus and angiographic coronary artery disease complexity are intertwined and unfavorably affect prognosis after percutaneous coronary interventions, but their relative impact on long-term outcomes after percutaneous coronary intervention with drug-eluting stents remains controversial. This study determined drug-eluting stents outcomes in relation to diabetic status and coronary artery disease complexity as assessed by the Synergy Between PCI With Taxus and Cardiac Surgery (SYNTAX) score. METHODS AND RESULTS In a patient-level pooled analysis from 4 all-comers trials, 6081 patients were stratified according to diabetic status and according to the median SYNTAX score ≤11 or >11. The primary end point was major adverse cardiac events, a composite of cardiac death, myocardial infarction, and clinically indicated target lesion revascularization within 2 years. Diabetes mellitus was present in 1310 patients (22%), and new-generation drug-eluting stents were used in 4554 patients (75%). Major adverse cardiac events occurred in 173 diabetics (14.5%) and 436 nondiabetic patients (9.9%; P<0.001). In adjusted Cox regression analyses, SYNTAX score and diabetes mellitus were both associated with the primary end point (P<0.001 and P=0.028, respectively; P for interaction, 0.07). In multivariable analyses, diabetic versus nondiabetic patients had higher risks of major adverse cardiac events (hazard ratio, 1.25; 95% confidence interval, 1.03-1.53; P=0.026) and target lesion revascularization (hazard ratio, 1.54; 95% confidence interval, 1.18-2.01; P=0.002) but similar risks of cardiac death (hazard ratio, 1.41; 95% confidence interval, 0.96-2.07; P=0.08) and myocardial infarction (hazard ratio, 0.89; 95% confidence interval, 0.64-1.22; P=0.45), without significant interaction with SYNTAX score ≤11 or >11 for any of the end points. CONCLUSIONS In this population treated with predominantly new-generation drug-eluting stents, diabetic patients were at increased risk for repeat target-lesion revascularization consistently across the spectrum of disease complexity. The SYNTAX score was an independent predictor of 2-year outcomes but did not modify the respective effect of diabetes mellitus. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifiers: NCT00297661, NCT00389220, NCT00617084, and NCT01443104.
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The research in this thesis is related to static cost and termination analysis. Cost analysis aims at estimating the amount of resources that a given program consumes during the execution, and termination analysis aims at proving that the execution of a given program will eventually terminate. These analyses are strongly related, indeed cost analysis techniques heavily rely on techniques developed for termination analysis. Precision, scalability, and applicability are essential in static analysis in general. Precision is related to the quality of the inferred results, scalability to the size of programs that can be analyzed, and applicability to the class of programs that can be handled by the analysis (independently from precision and scalability issues). This thesis addresses these aspects in the context of cost and termination analysis, from both practical and theoretical perspectives. For cost analysis, we concentrate on the problem of solving cost relations (a form of recurrence relations) into closed-form upper and lower bounds, which is the heart of most modern cost analyzers, and also where most of the precision and applicability limitations can be found. We develop tools, and their underlying theoretical foundations, for solving cost relations that overcome the limitations of existing approaches, and demonstrate superiority in both precision and applicability. A unique feature of our techniques is the ability to smoothly handle both lower and upper bounds, by reversing the corresponding notions in the underlying theory. For termination analysis, we study the hardness of the problem of deciding termination for a speci�c form of simple loops that arise in the context of cost analysis. This study gives a better understanding of the (theoretical) limits of scalability and applicability for both termination and cost analysis.
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Alzheimer's disease (AD) is the most common cause of dementia. Over the last few years, a considerable effort has been devoted to exploring new biomarkers. Nevertheless, a better understanding of brain dynamics is still required to optimize therapeutic strategies. In this regard, the characterization of mild cognitive impairment (MCI) is crucial, due to the high conversion rate from MCI to AD. However, only a few studies have focused on the analysis of magnetoencephalographic (MEG) rhythms to characterize AD and MCI. In this study, we assess the ability of several parameters derived from information theory to describe spontaneous MEG activity from 36 AD patients, 18 MCI subjects and 26 controls. Three entropies (Shannon, Tsallis and Rényi entropies), one disequilibrium measure (based on Euclidean distance ED) and three statistical complexities (based on Lopez Ruiz–Mancini–Calbet complexity LMC) were used to estimate the irregularity and statistical complexity of MEG activity. Statistically significant differences between AD patients and controls were obtained with all parameters (p < 0.01). In addition, statistically significant differences between MCI subjects and controls were achieved by ED and LMC (p < 0.05). In order to assess the diagnostic ability of the parameters, a linear discriminant analysis with a leave-one-out cross-validation procedure was applied. The accuracies reached 83.9% and 65.9% to discriminate AD and MCI subjects from controls, respectively. Our findings suggest that MCI subjects exhibit an intermediate pattern of abnormalities between normal aging and AD. Furthermore, the proposed parameters provide a new description of brain dynamics in AD and MCI.
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Nonlinear analysis tools for studying and characterizing the dynamics of physiological signals have gained popularity, mainly because tracking sudden alterations of the inherent complexity of biological processes might be an indicator of altered physiological states. Typically, in order to perform an analysis with such tools, the physiological variables that describe the biological process under study are used to reconstruct the underlying dynamics of the biological processes. For that goal, a procedure called time-delay or uniform embedding is usually employed. Nonetheless, there is evidence of its inability for dealing with non-stationary signals, as those recorded from many physiological processes. To handle with such a drawback, this paper evaluates the utility of non-conventional time series reconstruction procedures based on non uniform embedding, applying them to automatic pattern recognition tasks. The paper compares a state of the art non uniform approach with a novel scheme which fuses embedding and feature selection at once, searching for better reconstructions of the dynamics of the system. Moreover, results are also compared with two classic uniform embedding techniques. Thus, the goal is comparing uniform and non uniform reconstruction techniques, including the one proposed in this work, for pattern recognition in biomedical signal processing tasks. Once the state space is reconstructed, the scheme followed characterizes with three classic nonlinear dynamic features (Largest Lyapunov Exponent, Correlation Dimension and Recurrence Period Density Entropy), while classification is carried out by means of a simple k-nn classifier. In order to test its generalization capabilities, the approach was tested with three different physiological databases (Speech Pathologies, Epilepsy and Heart Murmurs). In terms of the accuracy obtained to automatically detect the presence of pathologies, and for the three types of biosignals analyzed, the non uniform techniques used in this work lightly outperformed the results obtained using the uniform methods, suggesting their usefulness to characterize non-stationary biomedical signals in pattern recognition applications. On the other hand, in view of the results obtained and its low computational load, the proposed technique suggests its applicability for the applications under study.