Theodoros Daglis

The COVID-19 pandemic necessitated the production of mathematical models that could explain and thoroughly study various aspects and features of the pandemic. In this work, we utilize mathematical modeling to model COVID-19 spread, also reflecting changes in growth rates over time. Empirically, we use data from January 2020 to May 2022, and accordi...

In 2015, all United Nations Member States adopted 17 Sustainable Development Goals (SDGs) for the 2030 agenda. Addressing the issue of employing alternative data sources for exploring aspects of utilizing said goals, this paper explores the Circular Economy dimension within the SDG12 score, focusing on responsible production and consumption and the...

The metaverse is perceived by numerous domains as having high potential for enhancing industry performance and serving as a valuable tool for academics, offering significant resources for teaching, experiential learning, and risk-free participation in various activities. Despite its considerable interest and importance, there has been a lack of res...

Background: The rapid development of COVID-19 vaccines may have raised public concerns about their safety and side effects in the United States (US). This study aimed to assess trends in online searches related to the safety and side effects of COVID-19 vaccines in the US from 2021-2022. Methods: Google COVID-19 Vaccination Search Insights was used...

Background and Objectives Substance use disorders (SUD) are a major public health concern in the United States. This study examined racial/ethnic and state‐level disparities in SUD mortality in the United States from 2000 to 2019. Methods Age‐standardized mortality rates for SUD were obtained for 5 racial/ethnic groups (White respondents, Black re...

The COVID-19 pandemic necessitated the production of mathematical models that were able to explain and thoroughly study various aspects and features of the pandemic. In this work, we provide a well-stated mathematical model to explain and simulate the evolution of the COVID-19 pandemic. To test our model’s performance and validity, we utilize actua...

This paper presents a quantitative approach that captures the LinkedIn information that can be derived regarding companies and jobs that operate in a circular economy context. To do so, we perform this analysis for the regions of Spain, providing metrics for the standardization of the companies identified, for measurement reasons, while job posts a...

This work examines the direct impact of solar events on the financial sector of the United States, while also investigating their indirect effects on other sectors of the US economy. The study introduces a cutting-edge methodology based on the Global Vector Autoregressive (GVAR) model, utilizing a comprehensive dataset, to estimate indirect global...

It is not uncommon to encounter overoptimistic views among policy-makers concerning the extent to which the research outcome of a university can have an impact on the innovation and economic performance of a local economy. Policies and expectations are usually influenced by optimal cases of top-ranked universities in highly innovative geographies....

This study investigated the volatility linkages between energy and agricultural futures, including possible causes for these comovements, such as external macroeconomic and financial shocks during low and high volatility regimes. A combination of Markov‐switching regressions and quadrivariate VAR–DCC–GARCH and VAR–BEKK–GARCH modeling revealed that...

In this work, the effect of the COVID-19 pandemic on the major tourism-related cryptocurrencies is investigated. More precisely, the variable lag causality is used, to test whether data related to the pandemic and more precisely, confirmed cases and lockdown stringency index, cause the cryptocurrencies from the field of tourism. Then, a possible lo...

The COVID-19 pandemic necessitated the production of mathematical models that were able to explain and thoroughly study various aspects and features of the pandemic. In this work, we provide a well-stated mathematical model to explain and simulate the evolution of the COVID-19 pandemic. To test our models performance and validity , we utilize actua...

Definition In the 21st century, prior to the outbreak of the COVID-19 pandemic, numerous transformations were already underway in the field of employment. However, this unprecedented global health crisis has had a profound influence on employment worldwide, yielding both positive and negative outcomes across various labor aspects. Consequently, whi...

Based on what we know today, there is a strong linkage between solar activity and the energy sector. In this work, we study the linkage between extreme solar events and the US energy sector, utilizing a sectoral supply chain dataset that spans the period 1998–2014. To do so, we propose a novel methodological approach by linking all the sectors of t...

Circular Economy (CE) is continuously evolving in terms of integrated industries, adoption of new strategies, and recognition levels. The vital elements of the CE have been the RE strategies acting as the guidelines and most important action toward the adoption of more circular production and consumption models. In this work, we examined data from...

In this work, we analyze the high-frequency time series of the deposits collected from the systemic biggest Greek banks during the recent economic crisis in Greece. Our focus has been to reveal hidden fractal and periodic patterns using a hybrid approach, which combines correlation and frequency analysis of the original and difference series in a s...

The circular economy is an important field of study, as evidenced by the increasing recent interest in academia and business as a result of contemporaneous policy directions. As reported in the literature, the metrics for circular economy lack worldwide applicability. In this work, we extracted data from the LinkedIn platform regarding keywords ass...

Definition Sharing economy is a new type of economic performance with its main characteristic being the sharing among peers. This can be regarded as a new economical approach with the individuals sharing their remainder resources. In this way, there is less need for the possession of resources leading to a decrease in redundant production. However,...

Purpose The COVID-19 pandemic is known to have affected the logistics and supply chains; however, there is no adequate empirical evidence to prove in which way it has affected the relationship between the stocks related to this field with the corresponding cryptocurrencies. This paper aims to test the dynamic relationship of cryptocurrencies with s...

In the Internet age, companies utilize social media platforms to increase their network, visibility, and profits. LinkedIn is one of the most popular such platforms, offering profile hosting and several basic services for free that both companies and customers make good use of. In this study, data-driven and qualitative approaches of assessing the...

Definition The increase in addiction during COVID-19 is a condition that emerged as an aftermath of COVID-19-related events, for instance, fear of the spread of COVID-19, self-abstention from many activities, and restrictions established by the lockdown measures. This condition includes substance addictions such as drugs and alcohol but also behavi...

The scientific community still struggles to understand the magnitude of the worldwide infections and deaths induced by COVID-19, partly ignoring the financial consequences. In this paper, using the autoregressive fractionally integrated moving average (ARFIMA)—general autoregressive conditional heteroskedasticity (GARCH) model, we quantify and show...

The aim of this paper is to conduct a data-driven approach of Circular Economy as an activity and a trend in companies located in 28 European countries. More precisely, we performed data mining from the LinkedIn, extracting the characteristics of each company, such as the number of employees, the date of foundation, the headquarters’ location, and...

Purpose By combining econometrics and multifractal methods, utilizing a financial framework, this paper will examine with objectivity the economic, financial and social impact of coronavirus disease 2019 (COVID-19) on society. Design/methodology/approach Through Granger causality, the authors test the effect of the COVID-19 pandemic on excessive g...

In this paper, we analyse how the Covid‐19 pandemic changed the dynamics of the euro to dollar exchange rate. To do so, we make use of spectral non‐causality tests to uncover the determinants of the euro to dollar exchange rate, using data that cover the pre‐Covid‐19 and the actual Covid‐19 era, by considering the exchange rate movements of other c...

The COVID-19 pandemic has already caused important negative consequences on the tourism industry globally. The lockdown measures suspended the tourism activities, and many tourists preferred to abstain from these activities in fear of the virus infection. As a result, investors have abandoned tourism-related companies’ stocks, impacting, even more,...

The Covid-19 pandemic has changed the dynamics of the overall economy, impacting many fields, including the agricultural sector. In this paper, we examine two important commodities of the agricultural sector, namely oats and wheat, during the Covid-19 spread and the lockdown measures. Using relevant time series specifications, we establish a hypoth...

Purpose This research paper uses a novel methodological approach to investigate the spillover effects among the key sectors of the US economy. Design/methodology/approach The paper links the US sectors via a node theoretic scheme based on a general equilibrium framework, whereas it estimates the general equilibrium equation as a Global Vector Auto...

We examine the impact of solar and space weather events on the Financial Select Sector SPDR Fund (XLF) price index volatility, spanning the period 1998-2018. Comparing MAPE and RMSFE forecasting criteria, for the ARIMA-GARCH model, augmented with exogenous variables, we find that solar and space weather variables contribute statistically significan...

We examine the impact of solar and geomagnetic events on Earth’s economic activity, and more precisely on the French telecommunications’ sector, in the 2000–2014 time span. We find that the sunspot number and the Dst index have predictive and forecasting ability on the evolution of the French telecommunications’ output. These results give credit to...

Although the impact of solar events on economic activity appears to be of great importance, very limited work has been done, so far, on the subject. In this work, we examine the impact of geomagnetic anomalies, caused by solar weather, on Earth's economic activity, and more precisely, on the US telecommunication sector, for the period January 1996–...

An updated catalog is created of 303 well-defined high-speed solar wind streams that occurred in the time period 2009 – 2016. These streams are identified from solar and interplanetary measurements obtained from the OMNIWeb database as well as from the Solar and Heliospheric Observatory (SOHO) database. This time interval covers the deep minimum ob...