14 research outputs found

    Impacts Of Credit Rating Announcements On Share Price In The NASDAQ Market And The Role Of The Credit Rating Agencies

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    The purpose of this paper is to investigate the response of the stock prices of firms based on NASDAQ Select Market, during the Credit Rating Announcements made by one of the major rating agencies, Standard and Poor’s, before and after the Great Financial Crisis of 2007-2008. The test procedure is the application of the event study by which we are going to investigate whether or how much the markets respond to Credit Rating Announcements. Furthermore, some important added implications would be if the results suggest the existence of an asymmetric response according to the differences between upgrading, stable grading and downgrading, or between firms with different size of capitalization, as well as whether the strength of the response has changed after the 2008.Our empirical research showed that the firms that were assigned negative rating before the financial crisis, experienced a strong negative impact on their stock price. On the contrary, stable grading or up grading have no strong effect. However, it is shown that after the 2008 no Credit Rating Announcement has strong effect on the firms’ stock price. An analysis behind this intuition is provided

    TECHNICAL AND TACTICAL ANALYSIS OF GOAL SCORING PATTERNS IN THE 2018 FIFA WORLD CUP IN RUSSIA

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    The aims of this research are to record and analyze the goals scored during the 64 matches in the 21st World Cup in Russia in 2018, to highlight those factors that are directly related to the teams’ effectiveness in scoring, to record the goals approved after the use of the new technologies, video assistant referee and goal line technology, as well as their effect on the outcome of the game. Chi-square and univariate general linear methods were used for the data analysis. Statistical difference is observed in the number of goals scored between the two halves (X²=8.699, p<0.005). A comparable percentage of scoring in most of the periods with exceptions of the periods in over time, the period 16th to 30th min, the addition time of the first and second half and the period 76th to 90th min of the game is determined (p<0.01). The teams that scored first won 71.4% matches, lost 9.5% and had a tie 19% of the matches (X²=42.000, p<0.001). Most of the goals were scored following a corner kick (24), penalty (22) and free kick scored non-directly (16), which were significantly different from free kick scored directly (6) and throw in (2) (X²=26.857, p<0.001). 19 goals were scored from cross, 19 from a long-range shot (8 of them with the “inner foot”), 18 from a forward pass and 12 from cutback. Statistical differences between the first four groups and all of the others are determined (X²=27.818, p<0.01). Significant differences were found between the goals that “began” from the offensive third, the middle and the defensive third (X²=73.645, p<0.001). 58.9% of the goals are scored following positional play, which is significantly different compared to counter attack (29.5%) and direct play (11.6%) (X²=32.611, p<0.001). Over 59 goals were scored from “the inner part of the foot” or “place”, and 31 from header, which were significantly different from the other types of shot (X²=89.254, p<0.001)

    Validation of the TROPOMI/S5P aerosol layer height using EARLINET lidars

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    The purpose of this study is to investigate the ability of the Sentinel-5P TROPOspheric Monitoring Instrument (TROPOMI) to derive accurate geometrical features of lofted aerosol layers, selecting the Mediterranean Basin as the study area. Comparisons with ground-based correlative measurements constitute a key component in the validation of passive and active satellite aerosol products. For this purpose, we use ground-based observations from quality-controlled lidar stations reporting to the European Aerosol Research Lidar Network (EARLINET). An optimal methodology for validation purposes has been developed and applied using the EARLINET optical profiles and TROPOMI aerosol products, aiming at the in-depth evaluation of the TROPOMI aerosol layer height (ALH) product for the period 2018 to 2022 over the Mediterranean Basin. Seven EARLINET stations were chosen, taking into consideration their proximity to the sea, which provided 63 coincident aerosol cases for the satellite retrievals. In the following, we present the first validation results for the TROPOMI/S5P ALH using the optimized EARLINET lidar products employing the automated validation chain designed for this purpose. The quantitative validation at pixels over the selected EARLINET stations illustrates that the TROPOMI ALH product is consistent with the EARLINET lidar products, with a high correlation coefficient R=0.82 (R=0.51) and a mean bias of -0.51±0.77 km and -2.27±1.17 km over ocean and land, respectively. Overall, it appears that aerosol layer altitudes retrieved from TROPOMI are systematically lower than altitudes from the lidar retrievals. High-albedo scenes, as well as low-aerosol-load scenes, are the most challenging for the TROPOMI retrieval algorithm, and these results testify to the need to further investigate the underlying cause. This work provides a clear indication that the TROPOMI ALH product can under certain conditions achieve the required threshold accuracy and precision requirements of 1 km, especially when only ocean pixels are included in the comparison analysis. Furthermore, we describe and analyse three case studies in detail, one dust and two smoke episodes, in order to illustrate the strengths and limitations of the TROPOMI ALH product and demonstrate the presented validation methodology. The present analysis provides important additions to the existing validation studies that have been performed so far for the TROPOMI S5P ALH product, which were based only on satellite-to-satellite comparisons.</p

    Το δεύτερο κονσέρτο για πιάνο του Προκόφιεφ Op.16 σε Σολ-Ελάσσονα (Ιστορικό πλαίσιο και Ερμηνευτική ανάλυση)

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    Η εργασία επικεντρώνεται στην ερμηνευτική προσέγγιση και ανάλυση του δευτέρου κονσέρτου για πιάνο του Σεργκέι Προκόφιεφ op.16, κυρίως από τη σκοπιά του ερμηνευτή σολίστα. Για να επιτευχθεί ο παραπάνω στόχος, τόσο το ίδιο το έργο, όσο και ο συνθέτης, προσδιορίζονται ιστορικά κατά τα πρώτα κεφάλαια, ενώ παράλληλα γίνεται και μια περιεκτική αναφορά σε ότι έχει να κάνει με τη μουσική γλώσσα, τις πιανιστικές καινοτομίες αλλά και τα δομικά χαρακτηριστικά που συναντά κανείς στις συνθέσεις του Προκόφιεφ. Στη συνέχεια η ανάλυση του κονσέρτου απαρτίζεται από την αμιγώς δομική ανάλυση, κατά την οποία αντιλαμβάνεται κανείς τη μορφή κάθε μέρους της σύνθεσης, ενώ στην πορεία το εκτενές κεφάλαιο της ερμηνείας του έργου, αναδεικνύει με όσο γίνεται πιο αντικειμενικό τρόπο, όλες εκείνες τις ανάγκες (τεχνικές, ερμηνευτικές κλπ.) που απαιτείται να καλυφθούν, ώστε να γίνει τελικά λόγος περί μίας επιτυχούς ερμηνείας του έργου.This essay focuses on the interpretive approach and analysis of Sergei Prokofiev’s second piano concerto op.16, mainly from the soloist’s perspective. In order for the above goal to be achieved, the piece, as well as the composer, are historically defined in the first chapters. At the same time, there is a brief mention of the musical language, the pianistic innovations as well as the structural elements one finds in Prokofiev’s compositions. Then, the analysis of the concerto is entirely structural, during which one can understand the form of every part of the composition. Finally, the long chapter discussing the interpretation of the piece, points out as objectively as possible all the requirements needed (technical, interpretive etc.) in order to talk about a successful interpretation of the piece

    Mechanical Properties of AA2024 Aluminum/MWCNTs Nanocomposites Produced Using Different Powder Metallurgy Methods

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    Metal matrix composites are a class of materials with high potential for industrial application due to the multifaceted properties that they possess. In the present research, mechanical alloying via ball milling was used to produce AA2024 powder that was subsequently reinforced with multiwalled carbon nanotubes (MWCNTs). Dispersion of the MWCNTs in the AA2024 matrix was achieved also by ball milling. Two different powder metallurgy sequencies, (i) double pressing double sintering and (ii) hot pressing were used for compaction and consolidation of the AA2024 reinforced by MWCNTs. The produced nanocomposites outperform the pristine AA2024 in terms of compressive strength, elongation to failure, and microhardness. The strengthening mechanism was associated with the homogeneous distribution of MWCNTs in the AA2024 matrix and their efficient interfacial bonding, which was attested also by microstructural characterization. Hot pressing resulted in higher mechanical properties of the nanocomposite material. However, when reinforcement content was above 2 wt.% a dramatic decrease of mechanical properties was observed, attributed to clustering and inhomogeneous dispersion of the MWCNTs. The homogeneous dispersion of MWCNTs in the AA2024 matrix and the retaining of their structural integrity are pivotal in increasing the mechanical properties, which can be directly associated with the efficient interfacial load transfer between MWCNTs and AA2024 matrix

    A Framework for Managing Interest in Technical Debt: An Industrial Validation

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    Technical debt management entails the quantification of principal and interest. In our previous work we had introduced a framework for calculating the Technical Debt Breaking Point (TD-BP), which is a point in time where the accumulated interest becomes larger than the principal; thus the debt of the company is no longer sustainable after this point in time. In this paper, we instantiate this framework and validate its ability to assess the breaking point of source code modules in an industrial setting. The results of the validation suggest that the calculated TD-BP is strongly correlated to experts’ opinion on the sustainability of modules, and that it can accurately rank components, based on their maintenance difficulty

    Residual Forest Biomass in Pinus Stands: Accumulation and Biogas Production Potential

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    Lignocellulosic biomass is an abundant resource that can be valorized for the production of bioenergy. However, studies aiming to quantify the amount of biogas production potential per km forest road are scarce in the literature. In this study, fresh pine needles, pine needle litter, pine branches, and pine bark were digested in batch reactors under mesophilic conditions after a grinding/milling pre-treatment. All samples were collected from a low-altitude Mediterranean Pinus forest (North Greece) adjacent to a category G forest road with a gentle slope. The methane yield of fresh pine needles was between 115 and 164 NmL g−1 volatile solids (VS), depending on the Pinus tree size. Pine needle litter produced a significantly lower methane yield (between 58 and 77 NmL g−1 VS), followed by pine bark (85 NmL g−1 VS) and pine branches (138 NmL g−1 VS). Considering the quantity of pine needle litter accumulated on adjacent forest roads (600 ± 200 g m−2), it was possible to calculate the biomethane production potential per km of forest road (up to 500 Nm3 km−1) if the biomass collected was disposed of at an anaerobic digestion facility. The results of the study demonstrate that residual forest biomass represents an additional resource for bioenergy production. Moreover, harvesting residual forest biomass can decrease the incidence of devastating summer forest fires and their disastrous consequences for the environment, the economy, and the local populations
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