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result(s) for
"Michail, Georgios"
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High cognitive load enhances the susceptibility to non-speech audiovisual illusions
2018
The role of attentional processes in the integration of input from different sensory modalities is complex and multifaceted. Importantly, little is known about how simple, non-linguistic stimuli are integrated when the resources available for sensory processing are exhausted. We studied this question by examining multisensory integration under conditions of limited endogenous attentional resources. Multisensory integration was assessed through the sound-induced flash illusion (SIFI), in which a flash presented simultaneously with two short auditory beeps is often perceived as two flashes, while cognitive load was manipulated using an n-back task. A one-way repeated measures ANOVA revealed that increased cognitive demands had a significant effect on the perception of the illusion while post-hoc tests showed that participants’ illusion perception was increased when attentional resources were limited. Additional analysis demonstrated that this effect was not related to a response bias. These findings provide evidence that the integration of non-speech, audiovisual stimuli is enhanced under reduced attentional resources and it therefore supports the notion that top-down attentional control plays an essential role in multisensory integration.
Journal Article
Early beta oscillations in multisensory association areas underlie crossmodal performance enhancement
by
Senkowski, Daniel
,
Michail, Georgios
,
Holtkamp, Martin
in
Audiovisual
,
Beta band
,
Clinical trials
2022
The combination of signals from different sensory modalities can enhance perception and facilitate behavioral responses. While previous research described crossmodal influences in a wide range of tasks, it remains unclear how such influences drive performance enhancements. In particular, the neural mechanisms underlying performance-relevant crossmodal influences, as well as the latency and spatial profile of such influences are not well understood. Here, we examined data from high-density electroencephalography (N = 30) recordings to characterize the oscillatory signatures of crossmodal facilitation of response speed, as manifested in the speeding of visual responses by concurrent task-irrelevant auditory information. Using a data-driven analysis approach, we found that individual gains in response speed correlated with larger beta power difference (13–25 Hz) between the audiovisual and the visual condition, starting within 80 ms after stimulus onset in the secondary visual cortex and in multisensory association areas in the parietal cortex. In addition, we examined data from electrocorticography (ECoG) recordings in four epileptic patients in a comparable paradigm. These ECoG data revealed reduced beta power in audiovisual compared with visual trials in the superior temporal gyrus (STG). Collectively, our data suggest that the crossmodal facilitation of response speed is associated with reduced early beta power in multisensory association and secondary visual areas. The reduced early beta power may reflect an auditory-driven feedback signal to improve visual processing through attentional gating. These findings improve our understanding of the neural mechanisms underlying crossmodal response speed facilitation and highlight the critical role of beta oscillations in mediating behaviorally relevant multisensory processing.
Journal Article
HPV-Based Self-Sampling in Cervical Cancer Screening: An Updated Review of the Current Evidence in the Literature
by
Daponte, Athina-Ioanna
,
Garas, Antonios
,
Bogdanos, Dimitrios P.
in
Adaptation
,
Cancer
,
Cancer screening
2023
Identifying and reaching women at higher risk for cervical cancer is all-important for achieving the ambitious endpoints set in 2020 by the WHO for global cervical cancer control by 2030. HPV-based (vaginal) self-sampling (SS) represents a cost-effective screening strategy, which has been successfully implemented during the last decade both in affluent and constrained settings. Among other advantages, SS strategies offer convenience, diminished costs, flexibility to obtain a sample in the office or home, avoiding a pelvic exam and uncomfortable appointment with a healthcare professional, as well as social and cultural acceptability. SS implementation has been globally boosted during the COVID-19 pandemic. In pragmatic terms, social distancing, local lockdowns, discontinuation of clinics and reallocation of human and financial resources challenged established clinician-based screening; self-collection strategies apparently surpassed most obstacles, representing a viable and flexible alternative. With time, sufficient reassuring data has accumulated regarding specially designed SS devices, aspects of sample preparation, transport and storage and, importantly, optimization of validated PCR-based HPV testing platforms for self-collected specimens. Suboptimal rates of clinical follow-up post-SS screening, as well as overtreatment with reliance solely on molecular assays, have both been documented and remain concerning. Therefore, effective strategies are still required to ensure linkage to follow-up testing and management following positive SS results by trained health professionals with knowledge of HPV biology and management algorithms. Because of the prolonged SS screening intervals, implementation data are limited regarding subsequent screening rounds of SS-screened individuals; however, these are accumulating gradually. With further refinement of assays and validation of novel biomarkers in self-collected samples, there is a clear potential for increasing SS accuracy and PPV. The potential differentiation of self-collection protocols for vaccinated versus non-vaccinated individuals also represents an open issue. In conclusion, HPV-based self-collection techniques can effectively address limited uptake alongside other conventional cervical screening drawbacks; however, assays, logistics and infrastructures need further optimization to increase the efficacy, effectiveness and cost-effectiveness of SS approaches.
Journal Article
Prostate cancer tissue mapping and stratification using DRAQ5 and Eosin fluorescent labels integrated with AI classification and segmentation algorithms
by
Wilson, Anna
,
Evangelou, Ioulia
,
Papachristos, Michail Georgios
in
Algorithms
,
Artificial intelligence
,
Biobanks
2026
Fluorescent microscopy using the DRAQ5 and Eosin probes has been shown in the literature to be capable of producing rapid tissue characterization through synthetic H&E-like pseudoimages, which can be potentially utilized in the clinic. This study focuses on developing deep learning models for classification and segmentation of prostate tissue labeled with DRAQ5&Eosin. The fluorophores provide highly specific features of nuclear and cytoplasmic content that allows for enhanced spatial resolution and multi-parametric analytics. The inter-dependencies of image acquisition and configuration variability on AI predictive accuracy is systematically interrogated. We are thus able to establish limits on experimental and analytical robustness in automated Gleason Grading (1-5) tissue samples of prostate cancer.
A labeling technique based on a far-red DNA probe DRAQ5, and Eosin allowed us to generate a two-channel fluorescent readout of prostatic tissue samples. Deep learning networks were employed to classify and segment DRAQ5 and Eosin fluorescent image regions into healthy and high/low grade cancerous tissue. A subset of images were acquired with variable microscopy configurations (focus, noise, zoom, lens) to evaluate the robustness of the proposed experimental-analytical pipeline and reproducibility of predictions.
Machine Leaning classifiers of High Grade Cancer (Gleason pattern 4 or 5) vs Healthy, Low Grade Cancer (Gleason pattern 3) vs Healthy, and High Grade Cancer vs Low Grade Cancer achieved an area under the curve of 0.9314, 0.8398, and 0.7715 respectively. Pixel wide cancer segmentation attained DICE scores of 0.8436, 0.5138, and 0.705 for background, healthy, and cancerous tissue respectively. The segmentation model also displayed robustness against a broad range of induced acquisition variability.
Overall, DRAQ5 and Eosin labeling in combination with AI tools demonstrate a potential pipeline used in diagnostic clinical application when employing fluorescent imaging. Future research could expand and bring this combined fluorescent biomarker and AI methodology to the clinic.
Journal Article
The ErbB Signaling Network and Its Potential Role in Endometrial Cancer
by
Adonakis, Georgios
,
Zarogianni, Evgenia
,
Styliara, Ioanna
in
Analysis
,
Apoptosis
,
Artificial intelligence
2023
Endometrial cancer (EC) is the second most common malignancy of the female reproductive system worldwide. The updated EC classification emphasizes the significant role of various signaling pathways such as PIK3CA-PIK3R1-PTEN and RTK/RAS/β-catenin in EC pathogenesis. Some of these pathways are part of the EGF system signaling network, which becomes hyperactivated by various mechanisms and participates in cancer pathogenesis. In EC, the expression of ErbB receptors is significantly different, compared with the premenopausal and postmenopausal endometrium, mainly because of the increased transcriptional activity of ErbB encoding genes in EC cells. Moreover, there are some differences in ErbB-2 receptor profile among EC subgroups that could be explained by the alterations in pathophysiology and clinical behavior of various EC histologic subtypes. The fact that ErbB-2 receptor expression is more common in aggressive EC histologic subtypes (papillary serous and clear cell) could indicate a future role of ErbB-targeted therapies in well-defined EC subgroups with overexpression of ErbB receptors.
Journal Article
From Seek-and-Destroy to Split-and-Destroy: Connection Partitioning as an Effective Tool against Low-Rate DoS Attacks
by
Kolias, Constantinos
,
Makrakis, Georgios Michail
,
Kampourakis, Vyron
in
Access control
,
Bandwidths
,
Business metrics
2024
Low-rate Denial of Service (LDoS) attacks are today considered one of the biggest threats against modern data centers and industrial infrastructures. Unlike traditional Distributed Denial of Service (DDoS) attacks that are mainly volumetric, LDoS attacks exhibit a very small network footprint, and therefore can easily elude standard detection and defense mechanisms. This work introduces a defense strategy that may prove particularly effective against attacks that are based on long-lived connections, an inherent trait of LDoS attacks. Our approach is based on iteratively partitioning the active connections of a victim server across a number of replica servers, and then re-evaluating the health status of each replica instance. At its core, this approach relies on live migration and containerization technologies. The main advantage of the proposed approach is that it can discover and isolate malicious connections with virtually no information about the type and characteristics of the performed attack. Additionally, while the defense takes place, there is little to no indication of the fact to the attacker. We assess various rudimentary schemes to quantify the scalability of our approach. The results from the simulations indicate that it is possible to save the vast majority of the benign connections (80%) in less than 5 min.
Journal Article
UNESCO Historic Centre (Chorá) of Patmos Island: Conservation and Reconstruction of a Collapsed Urban House
by
Tzamalis, Georgios
,
Michail, Georgios
,
Skitsas, Georgios
in
Architecture
,
Byzantine civilization
,
Chorá of Patmos
2022
Historic monuments in Greece represent part of the nation’s identity and, as such, they form a crucial part of local communities, not only culturally but also socially and economically. In the current paper, the design process of reconstructing a masonry two-story urban house from the late 19th century located in the historic center (Chorá) of a distant island in the Aegean Sea, Patmos, is discussed through related theories and actual design considerations. Chorá is protected as a UNESCO site; therefore, strict rules for the conservation of any structure enclosed within its boundaries apply. Analysis of the excavation findings and architectural drawings showing the current condition and the conservation proposal, together with the pathology of the building, as well as a structural analysis of the reconstructed structure, are thoroughly discussed in the present paper. These latter can serve as a record for the specific typology of the building and the processes engineers and architects must follow in order to obtain official permission to restore and even reconstruct collapsed parts of such traditional houses, while catering for climate change issues. The maintenance of the originality of the structure is of major importance and is thoroughly discussed, together with the detailed presentation of architectural and structural solutions serving this goal.
Journal Article
The Influence of Sexual Behavior and Demographic Characteristics in the Expression of HPV-Related Biomarkers in a Colposcopy Population of Reproductive Age Greek Women
by
Daponte, Athina-Ioanna
,
Galazios, Georgios
,
Pouliakis, Abraham
in
Artificial intelligence
,
Biomarkers
,
Biopsy
2021
Despite the significant scientific evolution in primary and secondary cervical cancer prevention in the battle started by George Papanicolaou in the previous century, global cervical cancer mortality rates remain disappointing. The widespread implementation of HPV-related molecular markers has paved the way to tremendous developments in cervical cancer screening, with the transition from cytological approach to the more accurate and cost-effective HPV testing modalities. However, the academic audience and different health systems have not yet adopted a universal approach in screening strategies, and even artificial intelligence modalities have been utilized from the multidisciplinary scientific armamentarium. Combination algorithms, scoring systems as well as artificial intelligent models have been so far proposed for cervical screening and management. The impact of sexual lifestyle inherently possesses a key role in the prevalence of HPV-related biomarkers. This study aimed to investigate any possible influence of sexual behavior and demographic characteristics in the expression of HPV-related biomarkers in a colposcopy population from October 2016 to June 2017, and corroborated the determining role of age at fist intercourse; the older the age, the lower the probability for DNA positivity. Multivariate analysis illustrated additionally that a number of sexual partners exceeding 4.2 was crucial, with women with ≤5 partners being approximately four times less likely to harbor a positive HPV DNA test (p < 0.0001). Similarly, a reported partner change during the last year before HPV DNA assessment contributed to 2.5 times higher odds for DNA positivity (p = 0.0006). From this perspective, the further development and validation of scoring systems quantifying lifestyle factors that could reflect cervical precancer risk seems paramount.
Journal Article
Cervical HPV Infections, Sexually Transmitted Bacterial Pathogens and Cytology Findings—A Molecular Epidemiology Study
by
Margari, Niki
,
Pouliakis, Abraham
,
Ieronimaki, Argyro-Ioanna
in
Bacteria
,
Bacterial diseases
,
Bacterial infections
2023
Prevalent cervical HPV infection and high-risk HPV persistence consequences have been extensively investigated in the literature; nevertheless, any causative interrelations of other sexually transmitted bacterial infections (STIs) with cervical HPV infection have not yet been fully elucidated. This study aimed to investigate the possible association of STIs with cervical cytology aberrations and HPV genotyping results in a representative sample of predominantly young Greek women. Liquid-based cytology and molecular detection for bacterial STIs and HPV as well as extended HPV genotyping were simultaneously assessed in cervical samples from 2256 individuals visiting several urban outpatient Gynecology Departments for well-woman visits or cervical screening throughout a 20-month period. All specimens were centrally processed with validated molecular assays. The mean age of the studied women was 37.0 ± 11.7 years; 722 women (33.30%) tested positive for STI (mean age 34.23 ± 10.87 years). A higher mean age (38.34 ± 11.83 years (p < 0.05)) was associated with negative STI testing. Chlamydia trachomatis was detected in 59 individuals (8.2%), Mycoplasma hominis in 156 (21.6%), Mycoplasma genitalium in 14 (1.9%), and Ureaplasma spp. in 555 (76.9%); infections with two bacterial pathogens were identified in 73 samples (10.1%). Cervical HPV was detected in 357 out of 1385 samples with a valid HPV typing result (25.8%). The mean age of HPV-positive women was 32.0 ± 8.4 years; individuals testing HPV-negative were slightly older (N = 1028): 34.4 ± 9.2 (p < 0.05). Among the 1371 individuals with valid results both for bacterial STIs and cervical HPV detection, women with an HPV-positive sample were more likely to harbor an STI (OR: 2.69, 95% CI 2.10–3.46, p < 0.05). Interestingly, bacterial STI positivity illustrated significant heterogeneity between NILM and LSIL cases, with 28.88% of NILM and 46.33% of LSIL cases harboring an STI, respectively (p < 0.05). In brief, in a population with a high prevalence for STIs, especially Ureaplasma spp., an association was documented between bacterial pathogen detection and cervical HPV infection, as well as abnormal cytology; these findings merit further investigation.
Journal Article
Mount Athos: Restoration of an Almost Extinct Type of 18th–19th C. UNESCO Masonry OX Stable
by
Dimitroulias, Konstantinos
,
Michail, Georgios
,
Flentzouris, Vasilakis
in
Architecture
,
Byzantine civilization
,
Central Archeological Council
2021
The present paper serves the purpose of presenting an extinct type of 18th–19th century masonry building, that of an ox-stable, situated in one of Europe’s most secluded areas: The Holy Monastery of Pantokrator in Mount Athos Peninsula. Architectural drawings and surveying plots of its current state can serve as a record and reference of this UNESCO site for scholars. Adding to that, an elaborated proposal for the reuse of the building is presented together with technical drawings, which were approved by Greece’s Central Archeological Council. The masonry rectangular building is founded on natural rock with masonry pillar footings of different heights. Hence, the elevation irregularity and the different elevations of the footings of the structure present an additional challenge for the structural analysis. Structural analysis with a finite element (FE) model of the restored structure was executed with SAP2000 software. Performing lateral force and response spectrum analyses, stresses and deformations at critical points of the structure were calculated. Comparing a set of simplifying structural checks with the elastic FE analysis performed, it was concluded that the proposed design is effective in improving the earthquake performance of the structure.
Journal Article