A comparison of tests for homoscedasticity using simulation and empirical data

Anastasios Katsileros,Nikolaos Antonetsis,Paschalis Mouzaidis,Eleni Tania,Penelope J. Bebeli,Alex Karagrigoriou 한국통계학회 2024 Communications for statistical applications and me Vol.31 No.1

The assumption of homoscedasticity is one of the most crucial assumptions for many parametric tests used in the biological sciences. The aim of this paper is to compare the empirical probability of type I error and the power of ten parametric and two non-parametric tests for homoscedasticity with simulations under dierent types of distributions, number of groups, number of samples per group, variance ratio and significance levels, as well as through empirical data from an agricultural experiment. According to the findings of the simulation study, when there is no violation of the assumption of normality and the groups have equal variances and equal number of samples, the Bhandary-Dai, Cochran’s C, Hartley’s Fmax, Levene (trimmed mean) and Bartlett tests are considered robust. The Levene (absolute and square deviations) tests show a high probability of type I error in a small number of samples, which increases as the number of groups rises. When data groups display a nonnormal distribution, researchers should utilize the Levene (trimmed mean), O’Brien and Brown-Forsythe tests. On the other hand, if the assumption of normality is not violated but diagnostic plots indicate unequal variances between groups, researchers are advised to use the Bartlett, Z-variance, Bhandary-Dai and Levene (trimmed mean) tests. Assessing the tests being considered, the test that stands out as the most well-rounded choice is the Levene’s test (trimmed mean), which provides satisfactory type I error control and relatively high power. According to the findings of the study and for the scenarios considered, the two non-parametric tests are not recommended. In conclusion, it is suggested to initially check for normality and consider the number of samples per group before choosing the most appropriate test for homoscedasticity.

A Novel Algorithm for Restricting the Complexity of Virus Typing via PCR-RFLP Gel Electrophoresis

Anastasios N. Delopoulos,Christos F. Maramis 대한의용생체공학회 2011 Biomedical Engineering Letters (BMEL) Vol.1 No.4

Purpose PCR-RFLP gel electrophoresis is a popular method for virus typing (i.e., for identifying the types of a virus that have infected a biological sample), which has been automated recently owing to a computerized typing methodology. However, even with the help of this methodology, the PCRRFLP method suffers from low throughput, when compared to other typing methods. In this paper, we tackle this issue by introducing a novel algorithm for conducting the most computationally demanding phase of the aforementioned typing methodology (testing phase). Methods The testing phase requires the execution of an optimization task on a 1d signal (intensity profile) for a number of type combinations. The introduced algorithm first partitions the signal into individually treatable segments. This parcels the optimization task into a set of more lightweight subproblems, thus reducing the computational effort required for testing a single intensity profile. Then, it eliminates any duplicate optimization subproblems among the type combinations. This way, the computational complexity of the testing phase is significantly restricted. Results A dataset of 70 natural samples infected by the human papillomavirus are employed to evaluate the complexity and the accuracy of the proposed algorithm. The obtained results are very promising, indicating that the proposed algorithm is able to octuple or more the speed of virus typing via the PCR-RFLP method, without essentially compromising the accuracy of the employed typing methodology. Conclusions The proposed algorithm can be seamlessly integrated into the state-of-the-art typing methodology to significantly increase the throughput of virus typing via the PCR-RFLP method, without harming the methodology’s accuracy. Moreover, it has the potential to be employed in real-time typing applications - one such application has just been reported.

Testicular microlithiasis in a boy with X-linked adrenal hypoplasia congenita

Anastasios Serbis,Vassiliki Regina Tsinopoulou,Konstantina Mouzaki,Eleni P. Kotanidou,Styliani Giza,Assimina GalliTsinopoulou 대한소아내분비학회 2018 Annals of Pediatirc Endocrinology & Metabolism Vol.23 No.3

X-linked adrenal hypoplasia congenita (AHC) is a rare disorder that usually presents clinically as adrenal insufficiency in early infancy. It is caused by mutations in the NR0B1 gene which is located on the short arm of chromosome X (Xp21). The NR0B1 gene plays an important role in normal development and function of both the adrenal and gonadal axes and some patients with the disease can present in adolescence with hypogonadotropic hypogonadism. Testicular microlithiasis is an ultrasonographic finding of unknown etiology that has been associated with several benign conditions such as cryptorchidism, congenital adrenal hyperplasia, varicoceles, and testicular malignancy. We report the case of an 11-year-old boy who was diagnosed at the age of 8 months with X-linked AHC due to adrenal failure and presented testicular microlithiasis during follow-up. To the best of our knowledge, this is the first case of an X-linked AHC patient diagnosed with testicular microlithiasis in follow-up.

REDEFINING LUXURY ADVERTISING: MOTIVATION IN ADVERTISED VALUE, ATTITUDES AND SUSCEPTIBILITY

Anastasios Panopoulos,Eirini Koronaki Eirini,Antigone Kyrousi,Athina Zotou 글로벌지식마케팅경영학회 2020 Global Marketing Conference Vol.2020 No.11

A scientometric, bibliometric, and thematic map analysis of hydraulic calcium silicate root canal sealers

Katakidis Anastasios,Kodonas Konstantinos,Fardi Anastasia,Gogos Christos 대한치과보존학회 2023 Restorative Dentistry & Endodontics Vol.48 No.4

Objectives: This scientometric and bibliometric analysis explored scientific publications related to hydraulic calcium silicate-based (HCSB) sealers used in endodontology, aiming to describe basic bibliometric indicators and analyze current research trends. Materials and Methods: A comprehensive search was conducted in Web of Science and Scopus using specific HCSB sealer and general endodontic-related terms. Basic research parameters were collected, including publication year, authorship, countries, institutions, journals, level of evidence, study design and topic of interest, title terms, author keywords, citation counts, and density. Results: In total, 498 articles published in 136 journals were retrieved for the period 2008– 2023. Brazil was the leading country, and the universities of Bologna in Italy and Sao Paolo in Brazil were represented equally as leading institutions. The most frequently occurring keywords were “calcium silicate,” “root canal sealer MTA-Fillapex,” and “biocompatibility,” while title terms such as “calcium,” “sealers,” “root,” “canal,” “silicate based,” and “endodontic” occurred most often. According to the thematic map analysis, “solubility” appeared as a basic theme of concentrated research interest, and “single-cone technique” was identified as an emerging, inadequately developed theme. The co-occurrence analysis revealed 4 major clusters centered on sealers’ biological and physicochemical properties, obturation techniques, retreatability, and adhesion. Conclusions: This analysis presents bibliographic features and outlines changing trends in HCSB sealer research. The research output is dominated by basic science articles scrutinizing the biological and specific physicochemical properties of commonly used HCSB sealers. Future research needs to be guided by studies with a high level of evidence that utilize innovative, sophisticated technologies.

Flow characteristics and alkalinity of novel bioceramic root canal sealers

Katakidis Anastasios,Sidiropoulos Konstantinos,Koulaouzidou Elisabeth,Gogos Christos,Economides Nikolaos 대한치과보존학회 2020 Restorative Dentistry & Endodontics Vol.45 No.4

Objective: This study aimed to examine the physical properties (pH and flow) of 2 novel bioceramic sealers. Materials: and Methods The tested sealers were a calcium hydroxide sealer (Sealapex) and 2 bioceramic sealers (BioRoot RCS and TotalFill BC Sealer). Flow measurements were conducted according to ISO 6876/2012, with a press method of 0.05 mL of sealer. The pH of fresh samples was tested immediately after manipulation, while set samples were stored for 3 times the recommended setting time. The predetermined time intervals ranged from 3 minutes to 24 hours for fresh samples and from 10 minutes to 7 days and 4 weeks for the set samples. Analysis of variance was performed, with p = 0.05 considered indicating significance. Results: The mean flow values were 26.99 mm for BioRoot, 28.19 for Sealapex, and 30.8 mm for TotalFill BC Sealer, satisfying the ISO standard. In the set samples, BioRoot RCS had higher pH values at 24 hours to 1 week after immersion in distilled water. At 2 weeks, both bioceramic sealers had similar pH values, greater than that of Sealapex. In the fresh samples, the bioceramic sealers had significantly higher initial pH values than Sealapex (p < 0.05). At 24 hours post-immersion, all sealers showed an alkaline pH, with the highest pH observed for TotalFill. Conclusions: The TotalFill BC Sealer demonstrated the highest flow. The bioceramic sealers initially presented higher alkaline activity than the polymeric calcium hydroxide sealer. However, at 3 and 4 weeks post-immersion, all sealers had similar pH values.

Metaheuristics as Enablers for VNF Scheduling in the Network Slice Set Up Process

Charismiadis, Stavros-Anastasios,Dimitris Tsolkas,Nikos Passas,Dionysis Xenakis,Lazaros Merakos 한국통신학회 2022 Journal of communications and networks Vol.24 No.6

Network slicing refers to the capability of composingmobile networks by chaining a set of virtualised functions ontop of shared infrastructures. In the research domain, specialattention is paid on the problem of scheduling network slices, i.e.,the challenge of managing efficiently computation resources whenmultiple network slices share the same infrastructure. So far, therich toolset that has emerged from the studies on the spectrumresource management, as well as the rapid development of cloudcomputing, have provided the means for scheduling decisions in5G networks. Capitalizing on the existing studies, we examinethe potential of using metaheuristic algorithms for providingscheduling outputs that minimize the slice set up time. Perfor-mance evaluation results show that evolution-based approaches(e.g., a genetic algorithm) provide better overall performancethan swarm-based ones (e.g., an ant colony optimiser). However,since the slice set-up process is a real-time process, the processingtime that is consumed by the scheduler itself is an importantevaluation factor, for which, the swarm-based approaches havean advantage.

Microalgal Biotechnology: Carotenoid Production by the Green Algae Dunaliella salina

진언선,Anastasios Melis 한국생물공학회 2003 Biotechnology and Bioprocess Engineering Vol.8 No.6

Unicellular green algae of the genus Dunaliella thrive in extreme environmental conditions such as high salinity, low pH, high irradiance and subzero temperatures. Species of Dunaliella are well known in the alga biotechnological industry and are employed widely for the production of valuable biochemicals, such as carotenoids. Some strains of Dunaliella are cultivated commercially in large outdoor ponds and are harvested to produce dry algal meals, such as polyunsaturated fatty acids and oils for the health food industry, and coloring agents for the food and cosmetic industries. During the past decade, the advances in molecular biology and biochemistry of microalgae, along with the advances in biotechnology of microalgal mass cultivation, enabled this microalga to become a staple of commercial exploitation. In particular, the advent of molecular biology and mutagenesis in Dunaliella has permitted enhancements in the carotenoids content of this green alga, making it more attractive for biotechnological applications. Accordingly, the present review summarizes the recent developments and advances in biotechnology of carotenoid production in Dunaliella.

A rare triple skeletal bone variation, including a median cleft of the posterior arch of the atlas, a sternal foramina and a bifid xiphoid process

Gregory Tsoucalas,Anastasios Vasilopoulos,Vasilios Thomaidis,Aliki Fiska 대한해부학회 2020 Anatomy & Cell Biology Vol.53 No.1

Bone variations are usually a result of abnormal ossification during embryonic life. Separately or in combination, sternal foramina and bifid xiphoid process are well documented skeletal alternations, as well as the median cleft of the posterior arch of the atlas. However, their appearance in combination is not yet celebrated in the literature. Our post-mortem examination unearthed such a triple variant of an adult male skeleton, which included no other skeletal variations. The fact that all variants are depicted in the median line of ossification implies a hypothesis of a triggered midline bone defect process. The awareness among clinicians of such variations during interventional and imaging procedures is of great importance.

IMPACT OF FEMVERTSING ON BRAND CREDIBILITY, BRAND AUTHENTCITY AND PURCHASE INTENTION

Athanasios Poulis,Anastasios Panopoulos,Prokopis Theodoridis,Ann-Kathrin Schmitt 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07

This study aims to investigate how attitudes towards femvertising affects brand credibility, brand authenticity, and purchase intention. Further, the mediation of femwashing on these relationships was investigated. And lastly, the impact of brand credibility and authenticity on purchase intention was examined. The results show that a favourable attitude towards femvertising positively affects brand credibility and authenticity but is not significant for purchase intention. Likewise, the mediation of femwashing on these relationships was not significant. In addition, brand credibility and brand authenticity had a positive impact on purchase intention.