Democritus University of Thrace
  • Komotiní, Thrace, Greece
Recent publications
The problem of solving algebraic Riccati equations (AREs) and certain linear matrix equations which arise from the ARE frequently occur in applied and pure mathematics, science, and engineering applications. In this article, by considering the nonsymmetric ARE (NARE) as a general form of ARE, the time-varying NARE (TV-NARE) problem is proposed and investigated. As a particular case of TV-NARE, the time-invariant NARE (TI-NARE) problem is investigated too. Then, by employing the zeroing (or Zhang) neural dynamics (ZND) design, a ZND TV-NARE (ZNDTV-NARE) model and a ZND TI-NARE (ZNDTI-NARE) model are proposed and investigated. Also, by combining the ZNDTV-NARE model with the frozen-time Riccati equation (FTRE) approach to optimal control of linear time-varying (LTV) systems based on the state-dependent Riccati equation (SDRE) process, a hybrid ZND FTRE control (HZND-FTREC) model is developed and investigated. The effectiveness of the proposed dynamical systems is proven in ten numerical experiments, three of which include applications to LTV and nonlinear systems.
Protecting online privacy using Virtual Private Networks (VPNs) is not as simple as it seems, since many well-known VPNs may not be secure. Despite appearing to be secure on the surface, VPNs can be a complete privacy and security disaster by stealing bandwidth, infecting devices with malware, installing tracking libraries, stealing personal data, and leaving data exposed to third parties. Therefore, Android users must exercise caution when downloading and installing VPN software on their devices. To this end, this paper proposes a neural network combined with a random forest that identifies malicious and malware-infected VPNs based on app permissions, along with a novel dataset of malicious and benign Android VPNs. The experimental results demonstrate that our classifier achieves high accuracy and outperforms other standard classifiers in terms of evaluation metrics such as accuracy, precision, and recall.
This work presents the roadmap for the development of a research impact case study as it evolves with research carried out at the University of the West of England, in the United Kingdom (UK). The focus of the research is using Machine Learning algorithms in supporting decision making in terms of appropriate nutrition and other key factors in treating patients in Critical Care Units (CCUs) of hospitals in the UK. A first stage of the research has sought to improve the accuracy and timeliness of patient referrals to dietitians, upon arrival at the CCU. The results have shown that among various machine learning classifiers using data from various physio-logical measures of CCU patients a Support Vector Machine (SVC) classifier was the best performing model (AUC: 0.78). An electronic dashboard has been developed to support a decision maker at the CCU to process referrals efficiently and support enhanced patient care. The research has been extended to a different area of interest, this time focusing on paediatric CCU patients. The aim here it to use similar research methodologies to attempt to estimate energy expenditure for very young patients. This bears the challenge of having to use limited sized datasets, which the researchers attempt to address with explainable Artificial Intelligence.
Introduction This study aimed to determine whether the introduction of anti-SARS-CoV-2 vaccines and the dominance of the omicron variant had a significant impact on the outcome of COVID-19 in patients with systemic autoimmune rheumatic diseases (SAIRDs). Methods Using data entered to the Greek Rheumatology Society COVID-19 registry, we investigated the incidence of hospitalization and death due to COVID-19, during the successive periods of the pandemic according to the prevalent strain (wild-type, Alpha, Delta, Omicron) in vaccinated and unvaccinated patients. Variables independently associated with hospitalization and death were explored using multivariate regression analyses, while Kaplan–Meier curves were used to depict survival data. Results From August 2020 until June 30, 2022, 456 cases (70.2% females) of COVID-19 with a mean age (± SD) of 51.4 ± 14.0 years were reported. In unvaccinated patients, the proportions of hospitalization and death were 24.5% and 4%, compared to 12.5% and 0.8% in the vaccinated group ( p < 0.001 for both comparisons). The rates of hospitalization for the wild-type, Alpha, Delta, and Omicron periods were 24.7%, 31.3%, 25.9%, and 8.1% respectively ( p < 0.0001), while the case fatality rates were 2.7%, 4%, 7%, and 0%, respectively ( p = 0.001). Using multivariable regression analysis, factors independently associated with hospitalization were infection by a non-Omicron variant, being non-vaccinated, exposure to rituximab, older age, and respiratory and cardiovascular disease. Independent predictors for death were contracting COVID-19 during the Alpha or Delta period, pulmonary disease, and older age, while being vaccinated was protective. Conclusions In this 2-year analysis, the rates of hospitalization and death among patients with SAIRDs have declined significantly. Vaccination and the dominance of the Omicron variant appear to be the major determinants for this shift. Key points • During the late phase of the pandemic, the proportion of severe COVID-19 cases, defined as requiring hospitalization or resulting in death, in patients with systemic autoimmune rheumatic diseases has declined. • Anti-SARS-CoV-2 vaccination and the dominance of the Omicron strain are the key factors that have independently contributed to this shift.
Objective The purpose of the study was to assess the efficacy of local ultrasound-guided methotrexate injection in patients with caesarean section scar pregnancy, to chart the course of beta-human chorionic gonadotropin levels (HCG) after treatment, and to see if HCG levels are correlated with clinical presentation. Methods Between May 2018 and January 2021, data were collected retrospectively from the Early Pregnancy Unit of a tertiary hospital. Results Our clinic assessed 20 patients; one disputed terminating the pregnancy and was not included in the research. The remaining 19 patients, with a median age of 34 years, received intragestational sac methotrexate injection under ultrasound guidance. 7w3d was the median gestational age. These women had one to four previous caesarean sections, with a mean of 1.60±9. Patients with caesarean scar pregnancy most typically presented with spotting (42.1%), whereas 26.3% were asymptomatic. Except in cases of pain, the symptomatic women’s HCG levels were lower than in the non-symptomatic women. The level of HCG in patients with pain was approximately double that of non-pain patients (p=0.2557). In our series, intragestational sac methotrexate injection was effective in 17/19 women, or 89.5% (95%CI: 75.7-100%). HCG levels were undetectable in 97.6±30 days on average (minimum: 42 days, maximum: 147 days). Conclusion Caesarean scar pregnancy is a rare possibly fatal condition with no consensus on the optimal treatment. An experienced Early Pregnancy Unit member performing local methotrexate injections under ultrasound guidance is a feasible and successful strategy in clinically stable patients.
In this paper, a new design approach for the six-port (SP) junction is introduced. The proposed design includes a generalized broadband matching and smooth miniaturization scheme and is extendable for any passive multiport structure. A multilayer technology and a microstrip to slot coupling operation are employed for the designed SP, which comprises power divider and three hybrid couplers. The conducted measurements of the constructed SP junctions validates the design approach. Optimal performance of the SP network in terms of miniaturization, bandwidth, and response accuracy were obtained for the 5G low band.
This narrative mini-review discusses vitamin E levels in subjects with diabetic foot ulcers (DFUs). Vitamin E may be reduced in subjects with DFUs, but this finding is inconsistent. Its administration appears to benefit patients with DM, delaying the onset of complications, including DFU. There is also evidence that it may promote DFU healing. Nonetheless, further studies are required to confirm these promising results and estimate vitamin E administration's cost-effectiveness
Approximately 40%-60% of all amputations are lower limb amputations (LLAs) related to diabetes mellitus (DM). The importance of quality of life (QoL) is increasingly recognized as after amputation. The objective of this cross-sectional study was to compare QoL (evaluated by Berg Balance Scale, BBS) in DM patients with unilateral transtibial amputation (TTA) using prosthesis (group A) with that of patients amputated due to other causes (group B). Overall, 32 patients completed two questionnaires: the 36-Item Health Survey (SF-36) for QoL assessment and the Trinity Amputation and Prosthesis Experience Scale-Revised (TAPES-R). In group A, patients were significantly older (P < .05) with shorter periods of prosthesis use (P < .05) and had significantly lower (P = .008) adjustment to limitation (TAPES-R). Correlations were found between BBS score and SF-36, including physical functioning (P < .001, r = 0.682), energy and fatigue (P < .001, r = 0.643) and emotional well-being (P < .001, r = 0.644). In the TAPES-R, a large negative correlation was found between BBS and activity restriction (P = .001, r =-0.595). Poorer balance ability, greater activity limitation, and worse psychosocial adjustment to the prosthesis were found in patients with unilateral TTA and DM compared to TTA prosthesis users without DM.
Relatively little research has been done in recent years to understand what leads to the unceasingly high rates of HIV sensory neuropathy despite successful antiretroviral treatment. In vivo and in vitro studies demonstrate neuronal damage induced by HIV and increasingly identified ART neurotoxicity involving mitochondrial dysfunction and innate immune system activation in peripheral nerves, ultimately all pathways resulting in enhanced pro-inflammatory cytokine secretion. Furthermore, many infectious/autoimmune/malignant diseases are influenced by the production-profile of pro-inflammatory and anti-inflammatory cytokines, due to inter-individual allelic polymorphism within cytokine gene regulatory regions. Associations of cytokine gene polymorphisms are investigated with the aim of identifying potential genetic markers for susceptibility to HIV peripheral neuropathy including ART-dependent toxic neuropathy. One hundred seventy-one people living with HIV in Northern Greece, divided into two sub-groups according to the presence/absence of peripheral neuropathy, were studied over a 5-year period. Diagnosis was based on the Brief Peripheral Neuropathy Screening. Cytokine genotyping was performed by sequence-specific primer-polymerase chain reaction. Present study findings identify age as an important risk factor (p < 0.01) and support the idea that cytokine gene polymorphisms are at least involved in HIV peripheral-neuropathy pathogenesis. Specifically, carriers of IL1a-889/rs1800587 TT genotype and IL4-1098/rs2243250 GG genotype disclosed greater relative risk for developing HIV peripheral neuropathy (OR: 2.9 and 7.7 respectively), while conversely, carriers of IL2+166/rs2069763 TT genotype yielded lower probability (OR: 3.1), all however, with marginal statistical significance. The latter, if confirmed in a larger Greek population cohort, may offer in the future novel genetic markers to identify susceptibility, while it remains significant that further ethnicity-oriented studies continue to be conducted in a similar pursuit.
Introduction Vitamin D plays a vital role as an essential nutrient for human health, but a significant number of people worldwide have a deficiency in this vitamin. Chronic Vitamin D deficiency has been linked to several adverse health outcomes, including musculoskeletal disorders, cardiovascular disease (CVD), cancer, and autoimmune disorders. Methodology We conducted a comprehensive literature search using academic databases, including PubMed, MEDLINE, Scopus, and Google Scholar. The search terms included “Vitamin D deficiency,” “chronic disease,” “musculoskeletal disorders,” “cardiovascular disease,” “cancer,” and “autoimmune disorders.” We focused on articles that examined the link between chronic Vitamin D deficiency and various health outcomes. Results Studies suggest that Vitamin D deficiency may contribute to several chronic diseases, including osteoporosis, osteoarthritis, hypertension, and CVD. Evidence indicates that inadequate levels of Vitamin D can increase the risk of certain types of cancer, such as colorectal and breast cancer. Studies have also found that people with autoimmune disorders, such as type 1 diabetes, multiple sclerosis, and rheumatoid arthritis, have lower levels of Vitamin D compared to healthy individuals. Conclusions The findings of this literature review highlight the importance of identifying and treating chronic Vitamin D deficiency to prevent or manage associated health conditions. Strategies to prevent Vitamin D deficiency include increased sun exposure, dietary changes, and Vitamin D supplementation. Regular screening for Vitamin D deficiency may also be necessary, particularly in high-risk populations. Clinicians should consider Vitamin D status when evaluating patients with chronic diseases and take appropriate steps to address any deficiencies.
This study aimed to: (i) verify the within-subject effect of the dominant and non-dominant upper limb propulsion during consecutive arm-pulls through discrete (average) and continuous analysis (SPM), and; (ii) compare young swimmers' propulsion between both upper limbs through discrete (average) and continuous analysis (Statistical Parametric Mapping-SPM). The sample consisted of 17 young male swimmers (age = 16.02 ± 0.61-years) who regularly participate in national and international level competitions. A set of kinematic and propulsion variables were measured during a 25-m maximal trial in front-crawl. Statistical analysis of propulsion was performed using discrete variables and through SPM. Swimming velocity showed a significant decrease over time. A significant interaction between the "time" (consecutive arm-pulls) and "side" (dominant vs. non-dominant) effects was observed in both statistical analyzes. Only the dominant upper limb demonstrated a significant "time" effect with a significant difference (p < 0.05) between the first and third arm-pulls. SPM indicated that the "time" effect was observed between the ~ 34% and ~ 42% of the arm-pull. The differences between the first and third arm-pull were verified between the ~ 32% and ~ 43% of the arm-pull. A non-significant "side" effect was verified in both analyzes. Therefore, SPM analysis provided more sensitive and accurate outputs than discrete analysis. This will allow coaches to design specific training drills focused on specific moments of the arm-pull.
Introduction: Recent advances in Artificial Intelligence (AI) and Computer Vision (CV) have led to automated pose estimation algorithms using simple 2D videos. This has created the potential to perform kinematic measurements without the need for specialized, and often expensive, equipment. Even though there’s a growing body of literature on the development and validation of such algorithms for practical use, they haven’t been adopted by health professionals. As a result, manual video annotation tools remain pretty common. Part of the reason is that the pose estimation modules can be erratic, producing errors that are difficult to rectify. Because of that, health professionals prefer the use of tried and true methods despite the time and cost savings pose estimation can offer. Methods: In this work, the gait cycle of a sample of the elderly population on a split-belt treadmill is examined. The Openpose (OP) and Mediapipe (MP) AI pose estimation algorithms are compared to joint kinematics from a marker-based 3D motion capture system (Vicon), as well as from a video annotation tool designed for biomechanics (Kinovea). Bland-Altman (B-A) graphs and Statistical Parametric Mapping (SPM) are used to identify regions of statistically significant difference. Results: Results showed that pose estimation can achieve motion tracking comparable to marker-based systems but struggle to identify joints that exhibit small, but crucial motion. Discussion: Joints such as the ankle, can suffer from misidentification of their anatomical landmarks. Manual tools don’t have that problem, but the user will introduce a static offset across the measurements. It is proposed that an AI powered video annotation tool that allows the user to correct errors would bring the benefits of pose estimation to professionals at a low cost.
This study explores the physiological evolution of entrepreneurship in the Robola PDO wine sector in Cephalonia, Greece, utilizing the Stra.Tech.Man Scorecard as a diagnostic tool. Focusing on micro-firms producing and marketing the Robola PDO wine variety, the research provides insights into the executives’ self-assessments of their strategic, technological, and management adaptation efforts from 2017 to 2021. The findings indicate that these firms exhibit a strong strategic ambition to improve their competitiveness, but encounter obstacles in technology and networking operations, as well as limitations in developing their human resources and their overall management methodologies. Furthermore, the study reveals that the companies’ innovation potential was enhanced during the COVID-19 pandemic. The study highlights the potential for developing a sophisticated regional wine brand and underscores the role of innovative entrepreneurs and government support in fostering a competitive and sustainable entrepreneurial ecosystem.
Unlabelled: Postpartum depression, with a prevalence ranging between 14% and 25% worldwide, has been considered an urgent health concern that negatively affects both mothers' and their infants' health. Postpartum depression may negatively affect maternal sociodemographic and anthropometric parameters and lifestyle factors. Nutrition has recently been identified as a crucial factor for the management and co-treatment of postpartum depression. This survey aims to determine the possible association of postpartum depression with mothers' socio-demographic and anthropometric characteristics, perinatal outcomes, breastfeeding practices, and Mediterranean diet (MD) adherence. Methods: This is a cross-sectional survey, which was performed on 3941 women during the postpartum period. Postpartum depression was assessed by the Edinburgh Postnatal Depression Scale (EPDS). Anthropometric parameters and perinatal outcomes were retrieved from mothers' medical records. Sociodemographic data and breastfeeding practices were recorded by face-to-face interviews between enrolled mothers and trained personnel. Mediterranean diet adherence was assessed by MedDietScore. Both univariate and multivariate binary logistic regression were applied for analyzing our data. Results: Postpartum depression was significantly associated with lower educational level, Greek nationality, higher prevalence of multiparity and overweight/obesity postpartum, higher incidence of caesarean section and not breastfeeding, and lower levels of MD adherence. In multivariate analysis, postpartum depression was independently associated with mothers' educational level, postpartum BMI status, type of delivery, breastfeeding practices, and MD adherence after adjusting for multiple confounding factors. Conclusions: This study has provided evidence that elevated MD compliance was related to a decreased risk of postpartum depression. Additionally, postpartum depression was associated with multiple sociodemographic and anthropometric parameters, perinatal outcomes, and breastfeeding practices. Future well-designed, prospective studies with high-quality methodology should be performed to obtain conclusive results.
The superfamily of human aldehyde dehydrogenases (hALDHs) consists of 19 isoenzymes which are critical for several physiological and biosynthetic processes and play a major role in the organism’s detoxification via the NAD(P) dependent oxidation of numerous endogenous and exogenous aldehyde substrates to their corresponding carboxylic acids. Over the last decades, ALDHs have been the subject of several studies as it was revealed that their differential expression patterns in various cancer types are associated either with carcinogenesis or promotion of cell survival. Here, we attempt to provide a thorough review of hALDHs’ diverse functions and 3D structures with particular emphasis on their role in cancer pathology and resistance to chemotherapy. We are especially interested in findings regarding the association of structural features and their changes with effects on enzymes’ functionalities. Moreover, we provide an updated outline of the hALDHs inhibitors utilized in experimental or clinical settings for cancer therapy. Overall, this review aims to provide a better understanding of the impact of ALDHs in cancer pathology and therapy from a structural perspective.
Antiphospholipid syndrome is an autoimmune disorder which is characterized by the presence of heterogeneous antiphospholipid antibodies. There is an evidence on antiphospholipid (aPL) antibodies related to thromboembolic events in cancer patients. In fact, the thrombotic complications in patients with malignancy occur at a rather high frequency, compared to other risk factors. In parallel with standard therapies available, there is need of case-by-case monitoring of each patient and the introduction of new therapies and need for more clinical trials which will address many questions for the optimal management of patients. This paper presents a basic review of the literature on the aPL antibodies associated with cardiovascular disease and cancer, as well as its complications, which are reported so far in the bibliography.
BACKGROUND: Carbohydrates as starch are a staple part of human diet. Upon starch digestion, glucose is absorbed, eliciting an insulin response. Glucose absorption kinetics (rapid or slow) depend on starch structure. Products made from wholemeal/wholegrain flour cause moderate glycemic and insulinemic responses and support a healthy lifestyle. OBJECTIVE: To review the nutritional value in terms of the in vivo glycemic and insulinemic index and the in vitro digestibility characteristics of six wholemeal/wholegrain commercial bakery products. METHODS: We analyzed in vitro the rapidly- and slowly- available glucose (RAG and SAG), the rapidly- and slowly- digestible starch (RDS and SDS), and the resistant starch (RS) fraction of the six wholemeal/wholegrain products against one white type of bread. The glycemic (GI) and the insulinemic index (II) were estimated in vivo in a group of eleven healthy individuals. RESULTS: The glycemic indices of the wholemeal/wholegrain flour biscuits and breads were low, (range 28 ± 3.2 to 41 ± 3.9, Mean+SEM) correlating with the insulinemic indices. RAG positively correlated with both GI and II, with fiber having a marginal correlation. CONCLUSIONS: Our findings indicate that both conventional and non-conventional wholemeal/wholegrain bakery products have low GI and moderate II, correlating to in vitro starch digestibility and type of processing.
The intermittent and volatile nature of renewable energy sources (RESs) has introduced new technical challenges that affect the secure and reliable grid operation. These challenges can be tackled at the RES level by reducing power fluctuations with the use of power smoothing (PS) techniques. Several PS methods have been proposed in the literature to smooth RES output exploiting battery energy storage systems (BESSs). However, a comprehensive comparative evaluation of PS methods is missing. Moreover, the effect of the long-term PS operation on the BESS life is usually ignored in such analyses. This article proposes a methodology for the systematic evaluation of well-established PS techniques, comparing their effectiveness on the PS of photovoltaic output based on various signal metrics. In addition, an accurate aging model for lithium-ion batteries is employed to investigate the impact of PS on the BESS lifetime, highlighting the main parameters that influence capacity degradation.
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Anastasios Zoupidis
  • Department of Primary Level Education
Achilleas Samaras
  • Department of Civil Engineering
Theofilos A Papadopoulos
  • Department of Electrical and Computer Engineering
University campus, 69100, Komotiní, Thrace, Greece
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