Sonia Malefaki

Dr. Sonia Malefaki

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Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 January 2025 in Aerospace
Verified
Journal Article
Open access
PDF file
SMSonia Malefaki
Sonia Malefaki
DMDionysios Markatos
Dionysios Markatos
Angelos FilippatosAngelos Filippatos
Angelos Filippatos
Spiros PantelakisSpiros Pantelakis
Spiros Pantelakis
The sustainability evaluation of engineering processes and structures is a multifaceted challenge requiring the integration of diverse and often conflicting criteria. To address this challenge, Multi-Criteria Decision-Making (MCDM) methods have emerged as effective tools. However, the selection of the most suitable MCDM approach for problems involving multiple criteria is critical to ensuring robust, reliable, and actionable outcomes. Equally significant is the choice of a proper normalization technique, which plays a pivotal role in determining the robustness and reliability of the results. This study investigates the impact of common MCDM tools on the decision-making process concerning diverse aspects of sustainability. It also examines how different normalization methods influence the final outcomes. Sustainability in this context is understood as a trade-off among five key dimensions: performance, environmental impact, economic impact, social impact, and circularity. The outcome of the MCDM process is represented by an aggregated metric, referred to as the Sustainability Index (SI). This index offers a comprehensive and robust framework for evaluating sustainability and facilitating decision-making when conflicting criteria are present. To assess the effects of implementing different MCDM and normalization choices on the sustainability assessment, a dataset from the aviation sector is employed. Specifically, a typical aircraft component is analyzed as a case study for holistic sustainability assessment, utilizing data that represent the various dimensions of sustainability mentioned above, for this component. Additionally, the study investigates the influence of initial data variations and weight variations within the MCDM process on the results. The results indicate that, overall, the different MCDM and normalization methods lead to similar outcomes when applied to the design alternatives. However, a deeper dive into the results reveals that the weighted sum method, when paired with min-max normalization, appears to be more appropriate, based on the use case involved for the present investigation, due to its robustness regarding small variations in the initial data and its sensitivity to large ones. This research underscores the critical importance of selecting appropriate MCDM tools and normalization methods to enhance transparency, robustness, reliability, and consistency of sustainability assessments within a holistic framework.

1 August 2007 in Archives of Clinical Neuropsychology
Verified
Journal Article
Open access
LML Messinis
L Messinis
ITI Tsakona
I Tsakona
SMSonia Malefaki
Sonia Malefaki
PPP Papathanasopoulos
P Papathanasopoulos
The present study sought to establish normative and discriminant validity data for Rey's Auditory Verbal Learning Test [Rey, A. (1964). L 'examen clinique en psychologie [Clinical tests in psychology]. Paris: Presses Universitaires de France; Schmidt, M. (1996). Rey auditory verbal learning test: A handbook. Los Angeles, CA: Western Psychological Services] using newly adapted learning lists for the Greek adult population. Applying the procedure suggested by Geffen et al. [Geffen, G., Moar, K. J., O'Hanlon, A. P., Clark, C. R., & Geffen, L. N. (1990). Performance measures of 16-86-year-old males and females on the auditory verbal learning test. The Clinical Neuropsychologist, 4, 45-63] we administered the test to 205 healthy participants, aged 18-78 years and two adult patient groups (long-term cannabis users and HIV symptomatic patients). Stepwise linear regression analyses showed that the variables age, education and gender contributed significantly to most trials of the RAVLT. Performance decreased in an age-dependent manner from young adulthood. Women, young adults and higher educated participants outperformed men, older adults and less educated individuals. The test appears to discriminate adequately between the performance of long-term heavy cannabis users and HIV seropositive symptomatic patients and matched healthy controls, as both patient groups performed more poorly than their respective control group. Normative data stratified by age, gender and education for the Greek adult population is presented for use in research and clinical settings.

14 March 2006 in Neurology
Verified
Journal Article
Closed access
LMLambros Messinis
Lambros Messinis
AKAnthoula Kyprianidou
Anthoula Kyprianidou
SMSonia Malefaki
Sonia Malefaki
PPPanagiotis Papathanasopoulos
Panagiotis Papathanasopoulos
The authors examined neuropsychological functioning in 20 long-term (LT), 20 shorter term (ST) heavy frequent cannabis users, and 24 controls after abstinence for > or =24 hours prior to testing. LT users performed significantly worse on verbal memory and psychomotor speed. LT and ST users had a higher proportion of deficits on verbal fluency, verbal memory, attention, and psychomotor speed. Specific cognitive domains appear to deteriorate with increasing years of heavy frequent cannabis use.

20 January 2011 in IEEE Transactions on Reliability
Verified
Journal Article
Closed access
OCOurania Chryssaphinou
Ourania Chryssaphinou
NLNikolaos Limnios
Nikolaos Limnios
SMSonia Malefaki
Sonia Malefaki
We consider repairable Multi-state reliability systems with components, the lifetimes and the repair times of which are -independent. The -th component can be either in the complete failure state 0, in the perfect state , or in one of the degradation states . The sojourn time in any of these states is a random variable following a discrete distribution. Thus, the time behavior of each component is described by a discrete-time semi-Markov chain, and the time behavior of the whole system is described by the vector of paired processes of the semi-Markov chain and the corresponding backward recurrence time process. Using recently obtained results concerning the discrete-time semi-Markov chains, we derive basic reliability measures. Finally, we present some numerical results of our proposed approach in specific reliability systems, namely series, parallel, k-out-of-n:F, and consecutive-k-out-of-n:F systems.

31 December 2017 in Behavioural Neurology
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Journal Article
Open access
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Lambros MessinisLambros Messinis
Lambros Messinis
Grigorios NasiosGrigorios Nasios
Grigorios Nasios
MKMary Kosmidis
Mary Kosmidis
PZPetros Zampakis
Petros Zampakis
SMSonia Malefaki
Sonia Malefaki
PPPanagiotis Papathanasopoulos
Panagiotis Papathanasopoulos
Cognitive impairment is frequently encountered in multiple sclerosis (MS) affecting between 40–65% of individuals, irrespective of disease duration and severity of physical disability. In the present multicenter randomized controlled trial, fifty-eight clinically stable RRMS patients with mild to moderate cognitive impairment and relatively low disability status were randomized to receive either computer-assisted (RehaCom) functional cognitive training with an emphasis on episodic memory, information processing speed/attention, and executive functions for 10 weeks (IG; n=32) or standard clinical care (CG; n=26). Outcome measures included a flexible comprehensive neuropsychological battery of tests sensitive to MS patient deficits and feedback regarding personal benefit gained from the intervention on four verbal questions. Only the IG group showed significant improvements in verbal and visuospatial episodic memory, processing speed/attention, and executive functioning from pre - to postassessment. Moreover, the improvement obtained on attention was retained over 6 months providing evidence on the long-term benefits of this intervention. Group by time interactions revealed significant improvements in composite cognitive domain scores in the IG relative to the demographically and clinically matched CG for verbal episodic memory, processing speed, verbal fluency, and attention. Treated patients rated the intervention positively and were more confident about their cognitive abilities following treatment.

1 April 2020 in Multiple Sclerosis and Related Disorders
Verified
Journal Article
Closed access
Lambros MessinisLambros Messinis
Lambros Messinis
MKMary Kosmidis
Mary Kosmidis
GNGrigorios Nasios
Grigorios Nasios
SKSpyridon Konitsiotis
Spyridon Konitsiotis
ANAikaterini Ntoskou
Aikaterini Ntoskou
PPPanagiotis Papathanasopoulos
Panagiotis Papathanasopoulos