On Turbulence and its Effects on Aerodynamics of Flow through Turbine Stages

In reality, the flows encountered in turbines are highly three‐dimensional, viscous, turbulent, and often transonic. These complex flows will not yield to understanding or prediction of their behavior without the application of contemporary and strong modeling techniques, together with an adequate turbulence model, to reveal effects of turbulence phenomenon and its impact on flow past turbine blades. The discussion primarily targets the turbulence features and their impact on fluid dynamics; streaming of blades, and efficiency performance. Turbulence as a phenomenon, turbulence effects and the transition onset in turbine stages are discussed. Flow parameters distribution past turbine stages, approaches to turbulence modeling, and how turbulent effects change efficiency and require an innovative design, among others are presented. Furthermore, a comparison study regarding the application and availability of various turbulence models is fulfilled, showing that every aerodynamic effect, encountered of flow pass turbine blades can be predicted via different model. This work could be very helpful for researchers and engineers working on prediction of transition onset, turbulence effects, and their impact on the overall turbine performance

The impact of social media on the destination image formation and tourist behavior

Social Media is becoming more important in the daily lives of consumers and can plays a major role in forming impressions about tourism destinations. This is especially true during the current pandemic, when traveling is restricted and people increase the time they spend online. Social media can play a distinguished role in searching for and sharing travel information. Moreover, social media also impacts travel decisions regarding which destination to select. Therefore it is particularly important for the tourism industry, where competition to attract tourists is the biggest concern. The purpose of this study is to find out the influence of social media on the destination image and impact on the visit decision

Factors for development of a wine tourism destination

Based on the concepts of tourism destination and wine tourism, the concept of wine tourism is defined. The system components of the destination for wine tourism are distinguished and characterized - wineries, wine routes, winescapes. The attributes of the destination that influence the visits to the wine region, are displayed. The factors for a successful development of a destination for wine tourism, which contribute to more real and memorable experiences of the wine tourist are systematized

Pregnancy Rates Associated with Oxidative Stress after Estrus Synchronization of Bulgarian Murrah Buffaloes in Breeding and Non-Breeding Season

Background: The current study aims to measure the effect of oxidative stress on the pregnancy rates of Bulgarian Murrah buffaloes during the breeding and non-breeding season. Methods: The study group consisted of 24 mature buffaloes more than 40 days after parturition. The following parameters were measured: Reactive Oxygen Species (ROS) products, Ascorbate radicals, Malondialdehyde (MDA), Nitric Oxide (NO), Super Oxide Dismutase (SOD), Glutathione peroxidase (GSH-Px), Protein Carbonyl Content (PPC), and total Nitric oxide. The Presynch/Ovsynch protocol was used for estrus synchronization. Results: A statistically significant increase in ROS products were measured in blood serum during the breeding season compared with the non-breeding season. The highest levels measured were in non-pregnant buffaloes during the breeding season. High levels of oxidative stress were registered due to low SOD activity in buffaloes during the breeding season compared to SOD activity during the non-breeding season. The highest SOD activity was observed in non-pregnant buffaloes during the summer season. The lowest GSH-Px levels were observed in non-pregnant buffaloes during both study periods. During the breeding season, concentrations of total NO and PPC were elevated. Conclusion: Comparing the obtained results for oxidative stress and antioxidant activity concerning pregnancy rate depending on the season showed that pregnancy in buffaloes during the breeding season was realized at higher values of NO and SOD. Increased oxidative stress was observed, resulting in a statistically significant increase in serum ROS products, as well as decreased SOD activity in buffaloes during the breeding season

IoT System Selection as a Fuzzy Multi-Criteria Problem

This research aims to analyse the applications of IoT in agriculture and to compare the most widely used IoT platforms. The problem of determining the most appropriate IoT system depends on many factors, often expressed by incomplete and uncertain estimates. In order to find a feasible decision, this study develops a multi-criteria framework for IoT solution selection in a fuzzy environment. In the proposed framework, a new modification of the Multi-Attribute Border approximation Area Comparison (MABAC) method with a specific distance measure via intuitionistic fuzzy values has been presented as a decision analysis method. The new technique is more precise than existing crisp and fuzzy analogues, as it includes the three components of intuitionistic numbers (degree of membership, degree of non-membership and hesitancy degree) and the relationships between them. The effectiveness of the new decision-making framework has been verified through an illustrative example of ranking IoT platforms

Effects of COVID-19 Pandemic on University Students’ Learning

The risk of COVID-19 in higher education has affected all its degrees and forms of training. To assess the impact of the pandemic on the learning of university students, a new reference framework for educational data processing was proposed. The framework unifies the steps of analysis of COVID-19 effects on the higher education institutions in different countries and periods of the pandemic. It comprises both classical statistical methods and modern intelligent methods: machine learning, multi-criteria decision making and big data with symmetric and asymmetric information. The new framework has been tested to analyse a dataset collected from a university students’ survey, which was conducted during the second wave of COVID-19 at the end of 2020. The main tasks of this research are as follows: (1) evaluate the attitude and the readiness of students in regard to distance learning during the lockdown; (2) clarify the difficulties, the possible changes and the future expectations from distance learning in the next few months; (3) propose recommendations and measures for improving the higher education environment. After data analysis, the conclusions are drawn and recommendations are made for enhancement of the quality of distance learning of university students

Clinical end results of patients with locally advanced esophageal carcinoma

Einleitung: Die Prognose der Patienten mit einem lokal fortgeschrittenen Ösophaguskarzinom ist nach wie vor sehr schlecht. Zielsetzung: Die primären Endpunkte dieser Arbeit waren das Überleben und das progressionsfreie Überleben im Gesamtkollektiv, das in zwei Therapie-Subgruppen analysiert wurde. Das progressionsfreie Überleben wurde zusätzlich in rezidivfreies und metastasenfreies Überleben unterteilt. Der sekundäre Endpunkt war der histomorphologische Regressionsgrad nach präoperativer Radiochemotherapie. Methodik: Retrospektiv analysiert wurden die Daten von 139 Patienten mit Ösophaguskarzinom, die an der Klinik für Strahlentherapie und Radioonkologie Charité Mitte und Virchow zwischen Januar 2002 und Dezember 2013 mit kurativem Therapieansatz behandelt wurden. Die Nachsorgedaten wurden bis zum Stichtag 30.11.2014 aktualisiert. Die mediane Beobachtungszeit betrug 14,13 Monate (1,5-120,07 Monate). Ergebnisse: Das mediane Alter betrug 65,57 Jahre, fast 80 % der Patienten waren Männer. Plattenepithelkarzinom bestand in 82,7 %, Adenokarzinom in 17,3 % der Fälle. 74,8 % der Tumoren waren im Stadium T3, 74,8 % der Patienten hatten zur Diagnosestellung positive Lymphknoten, 73,4 % der Tumoren waren im UICC-Stadium III A, B und C. Die Mortalität zum 30.11.2014 betrug 64,7 %. Eine komplette pathologische Remission nach präoperativer Radiochemotherapie bestand in 39,28 % der Fälle. Der histomorphologische Regressionsgrad war signifikant für das Überleben (p=0,021) und für das progressionsfreie Überleben (p=0,014). Das mediane Überleben im Gesamtkollektiv betrug 19,96 Monate. Das mediane Überleben in der Radiochemotherapie und Resektions-Gruppe (RCT+R-Gruppe) betrug 25,43 Monate und 11,13 Monate in der definitiven Radiochemotherapie-Gruppe (RCT-Gruppe) und unterschied sich signifikant (p=0,010). Die 1-,2-,3- und 5-Jahresüberlebensraten betrugen in der RCT+R-Gruppe 77,77 %, 56,94 %, 52,77% und 44,44 %, in der RCT-Gruppe 49,25 %, 35,82 %, 29,85 % und 25,37 %. Das progressionsfreie Überleben betrug 25,6 Monate im Gesamtkollektiv, 26,10 Monate in der RCT+R-Gruppe und 19,7 Monate in der RCT-Gruppe und unterschied sich nicht signifikant (p=0,459). Die progressionsfreien 1-,2-,3-, und 5-Jahresüberlebensraten betrugen 72,22 %, 61,11 %, 54,16 % und 48,61 % in der RCT+R-Gruppe und 71,64 %, 62,68 %, 56,71 % und 55,22 % in der RCT-Gruppe. Rezidivtumoren wurden in RCT+R-Gruppe bei 28 (38,88 %), Metastasen bei 25 Patienten diagnostiziert (34,72 %); in der RCT-Gruppe wurden Rezidivtumoren bei 18 (26,86 %), Metastasen bei 23 Patienten festgestellt (34,32 %). Das mediane rezidivfreie und metastasenfreie Überleben in der RCT+R-Gruppe betrugen 38,56 und 49,87 Monate, und in der RCT-Gruppe 41,63, bzw. 28,23 Monate. Schlussfolgerung: Es wurden signifikante Unterschiede im medianen Überleben beider Therapiegruppen festgestellt. Das progressionsfreie Überleben beider Gruppen war vergleichbar. Diese Ergebnisse stimmen mit dem aktuellen Forschungsstand überein.Introduction: The prognosis of patients with locally advanced esophageal carcinoma remains very poor. Purpose: The primary endpoints of this study were overall survival and progression-free survival in patient collective, divided into two subgroups based on therapy. Progression-free survival was separated into local recurrence- and metastases-free survival. The secondary endpoint was the histomorphological regression grading following preoperative chemoradiotherapy. Methods: Retrospective analysis of 139 patients with esophageal carcinoma, treated with a curative intention between January 2002 and December 2013 in the Clinic for Radiotherapy and Radiooncology Charité Mitte and Charité Virchow. Follow-up data was collected until the end date, 30.11.2014. Median follow-up time was 14,13 months (1,5-120,07 months). Results: Median age was 65,57 years, nearly 80 % patients were men. 82,7 % patients had squamous cell carcinoma, 17,3 % adenocarcinoma. Tumour stage T3 was diagnosed in 74,8 %, 74,8 % of the patients had positive lymph nodes at the time of diagnosis, 73,4 % of the tumours were in UICC stage III A, B and C. The mortality until 30.11.2014 was 64,7 %. Complete pathological remission following preoperative chemoradiotherapy was seen in 39,28 %. Histomorphological regression grading was a significant parameter for overall survival (p=0,021) and progression-free survival (p=0,014). Median overall survival of the entire patients collective was 19,96 months, 25,43 months in the chemoradiotherapy and resection-group (RCT+R-group) and 11,13 months in the definitive chemoradiotherapy-group (RCT-group) and differs significantly (p=0,010). 1-,2-,3-, and 5-years survival rates were 77,77 %, 56,94 %, 52,77 % and 44,44 % in the RCT+R-group, and 49,25 %, 35,82 %, 29,85 % and 25,37 % in the RCT-group respectively. Median progression-free survival was 25,6 months, 26,10 months in the RCT+R-group and 19,7 months in the RCT-group and differs not significantly. 1-,2-,3-, and 5-years progression-free survival rates were 72,22 %, 61,11%, 54,16 % and 48,61 % in the RCT+R-group and 71,64 %, 62,68 %, 56,71 % and 55,22 % in the RCT-group respectively. Local recurrences occured in 28 (38,88 %), metastases in 25 patients (34,72 %) in the RCT+R-group; in the RCT-group local recurrences occured in 18 (26,86 %), metastases in 23 patients (34,32 %). Median recurrence-free and metastases-free survival in the RCT+R-group were 38,56 and 49,87 months, in the RCT-group 41,63 and 28,23 months respectively. Conclusion: Median overall survival between both therapy groups differs significantly. Median progression-free survival in both therapy groups was similar. These results are consistent with the current state of research