GRB 221009A, The BOAT

GRB 221009A has been referred to as the Brightest Of All Time (the BOAT). We investigate the veracity of this statement by comparing it with a half century of prompt gamma-ray burst observations. This burst is the brightest ever detected by the measures of peak flux and fluence. Unexpectedly, GRB 221009A has the highest isotropic-equivalent total energy ever identified, while the peak luminosity is at the $\sim99$th percentile of the known distribution. We explore how such a burst can be powered and discuss potential implications for ultra-long and high-redshift gamma-ray bursts. By geometric extrapolation of the total fluence and peak flux distributions GRB 221009A appears to be a once in 10,000 year event. Thus, while it almost certainly not the BOAT over all of cosmic history, it may be the brightest gamma-ray burst since human civilization began.Comment: Resubmitted to ApJ

BurstCube: A CubeSat for gravitational wave counterparts

BurstCube aims to expand sky coverage in order to detect, localize, and rapidly disseminate information about gamma-ray bursts (GRBs). BurstCube is a\u276U\u27 CubeSat with an instrument comprised of 4 Cesium Iodide (CsI) scintillators coupled to arrays of Silicon photo-multipliers (SiPMs) and will be sensitive to gamma-rays between 50 keV and 1 MeV. BurstCube will assist current observatories, such as Swift and Fermi, in the detection of GRBs as well as provide astronomical context to gravitational wave (GW) events detected by LIGO, Virgo, and KAGRA. BurstCube is currently in its development phase with a launch readiness date in early 2022

Changes in the Surface Texture of Thermoplastic (Monomer-Free) Dental Materials Due to Some Minor Alterations in the Laboratory Protocol—Preliminary Study

Contemporary thermoplastic monomer-free prosthetic materials are widely used nowadays, and there are a great variety available on the market. These materials are of interest in terms of the improvement of the quality features of the removable dentures. The aim of this study is to establish how minimal changes in the laboratory protocol of polyamide prosthetic base materials influence the surface texture. Two polyamide materials intended for the fabrication of removable dentures bases were used—Perflex Biosens (BS) and VertexTM ThermoSens (TS). A total number of 20 coin-shaped samples were prepared. They were injected under two different modes—regular, as provided by the manufacturer, and modified, proposed by the authors of this study. Scanning electronic microscopy (SEM) under four magnifications—×1000, ×3000, ×5000, and ×10,000—was conducted. With minimal alterations to the melting temperature (5 °C) and the pressure (0.5 Bar), in Biosens, no changes in terms of surface improvement were found, whereas in ThermoSens, the surface roughness of the material significantly changed in terms of roughness reduction. By modifying the technological mode during injection molding, a smoother surface was achieved in one of the studied materials

Applications of Coupled Fixed Points for Multivalued Maps in the Equilibrium in Duopoly Markets and in Aquatic Ecosystems

We have obtained a new class of ordered pairs of multivalued maps that have pairs of coupled fixed points. We illustrate the main result with two examples that cover a wide range of models. We apply the main result in models in duopoly markets to get a market equilibrium and in aquatic ecosystems, also to get an equilibrium

Prophylactic Central Neck Lymph Node Dissection Adds No Short-Term Benefit to Total Thyroidectomy for Differentiated Thyroid Cancer

Background and Objectives: To answer the research question: “Is prophylactic central neck lymph node dissection (pCNLD) beneficial among differentiated thyroid carcinoma (DTC) patients?” Materials and Methods: This was a retrospective cohort study enrolling DTC patients treated at the University Hospital Kaspela, Bulgaria, from 30 January 2019 to October 2021. The predictor variable was presence of pCNLD (total thyroidectomy with vs. without pCNLD). The main outcome variables were postoperative complications (i.e., vocal cord paralysis, hypoparathyroidism, postoperative bleeding, and adjacent organ injury) and recurrence parameters. Appropriate statistics were computed with the significant level at p ≤ 0.05. Results: During the study period, 300 DTC patients (59.7% with pCNLD; 79.3% females) with an average age of 52 ± 2.8 years were treated. The mean follow-up period of the entire cohort was 45.8 ± 19.1 months. On bivariate analyses, TT with pCNLD, when compared to TT alone, required longer surgical time (mean difference: 9.4 min), caused nearly similar complications (except transient hypothyroidism: p = 0.04; relative risk, 1.32; 95% confidence interval, 1.0 to 1.73), and no significantly different recurrence events, time to recurrence, and recurrent sites. The benefit–risk analyses using the number needed to treat and to harm (NNT; NNH) also confirmed that TT plus pCNLD was not very beneficial in DTC management. Conclusion: The results of this study refute the benefit of pCNLD in DTC patient care with TT. Further well-designed studies in a larger cohort with a longer follow-up period are required to confirm this conclusion

Reputational Crisis Management: Co-authors monograph

International audienceКолективната монография „Управление на репутационни кризи” обобщава научните резултати от изследванията в докторската програма по медии и комуникации на Софийския университет в дисциплините „Кризисен мениджмънт – управление на репутационни кризи” и „Кризисен пъблик рилейшънс”, ръководени от проф. д-р Чавдар Христов. Включва следните аспекти: Организационна репутация; Глобализация на репутационните кризи; Алгоритъм за измерване на репутационни кризи; Методологична рамка на изследването на казуси (case studies); Управление на репутация, рискове и кризи; Управление на репутацията чрез жизнения цикъл на риска; Слуховете – външна заплаха за репутационна криза; Троловете и хакерите – външни заплахи за репутационна криза; Компютърните вируси и организационната репутация; Политическата карикатура и глобалните репутационни кризи; Репутационни аспекти на терористичните кризи; Репутационните кризи в туризма – „Брекзит” и гръцката финансова криза; Репутационна криза на държавните институции в България – бежанската криза; Репутационна криза на политическата власт в България – протестите #ДАНСwithme.Table of Contents PREFACE 1. ORGANIZATIONAL REPUTATION: COMMUNICATION AND MANAGEMENT ASPECTS. GLOBALIZATION OF REPUTATIONAL CRISES. Chavdar Hristov 1.1. Defining Organizational Reputation 1.2. Reputation from the Perspective of Mass Perceptions and Behavior 1.3. Reputation in Relation to the Corporate Image and Brand 1.4. Reputation as Added Value 1.5. Reputation as Unity between Presentation, Behavior and Communication 1.6. Managerial Aspects of Organizational Reputation 1.7. Globalization and Reputational Crises: Digitalization and Information Leaks 2. REAL, MEDIA‐REPORTED AND REPUTATIONAL CRISES. CRISIS MEASUREMENT. Chavdar Hristov 2.1. Real, Media‐Reported and Reputational Crises 2.2. Algorithm for Measurement and Analysis of Reputational Crises 2.3. Measuring and Investigating Crisis Situations 2.4. Conclusions and Implications 3. METHODOLOGICAL FRAMEWORK. Chavdar Hristov and Kalin Kalinov 3.1. Why case studies? 3.2. Research Design 3.3. Research Protocol 3.4. Validity Indicators 4. MANAGING REPUTATION, RISKS AND CRISES. THE FOUR CATEGORIES OF REPUTATIONAL RISKS AND GUIDELINES FOR THEIR MANAGEMENT. Petar Kardzhilov 4.1. The Term “Reputation” 4.2. Four Aspects of the Reputation Strategy 4.3. Contemporary Challenges in Reputation Management 4.4. Problem Management and Crisis Management 4.5. Four Categories of Reputational Risks 4.6. Guidelines for Managing Different Categoriesof Reputational Risks 4.7. Interconnected Risks 4.8. The Nuclear Disaster in Fukushima 4.9. Conclusion 5. MANAGING REPUTATION THROUGH THE LIFE CYCLE OF RISK. PREDICTING, PREVENTING AND RESOLVING REPUTATIONAL RISK. Petar Kardzhilov 5.1. Life Cycle of the Reputational Risk 5.2. Predicting Reputational Risks 5.2.1. External Radar for Reputational Risks and Horizon Scanning 5.2.2. Internal Radar for Reputational Risks 5.2.3. Risk Analysis 5.2.4. Evaluating Reputational Risk 5.3. Preventing Reputational Risks 5.3.1. Architecture of Reputational Risk Management – “Hard” Intervention for Reputational Risks Prevention 5.3.2. Reputational Behavior, Leadership and Training – “Soft” Intervention for Reputational Risk Prevention 5.3.3. Organizational Social Responsibility (Corporate Citizenship) 5.4. Solving Reputational Risks 5.5. Conclusion 6. RUMOURS AS AN EXTERNAL THREAT, LEADING TO REPUTATIONAL CRISES. Plamen Atanasov 6.1. Defining Rumor 6.2. Are Fake News a Rumor 6.3. Rumor from the Reputation Building Perspective 6.4. Rumor and Reputational Crises 6.5. Rumor and Intangible Assets 6.6. Rumors in the Cyberspace Extended Communication 6.7. Conclusion 7. TROLLS AND HACKERS‐ EXTERNAL THREATS LEADING TO REPUTATIONAL CRISES. Plamen Atanasov 7.1. Defining Hackers and Trolls or Why the Rumor, Hackers and Trolls are Major Threats for the Reputation in the Modern World 7.2. Correlating Hackers’ and Trolls’ Actions with Reputational Crises 7.3. Conclusion 8. COMPUTER VIRUSES AND WHY THE ORGANISATION REPUTATION SUFFERS. Plamen Atanasov 8.1. Defining Computer Viruses 8.2. Viruses from the Reputation Management Perspective 8.3. Protecting the Organizational Reputation from Virus Damage 8.4. Conclusion 9. THE IMPACT OF THE POLITICAL CARTOON ON GLOBAL REPUTATION CRISIS. Boyan Georgiev 9.1. Theoretical Framework and Methodology 9.2. Presenting the Cases of the Danish Newspaper “Jyllands‐Posten” and the French Weekly “Charlie Hebdo” 9.3. Key Variables Impacting the Development of the Crisis 9.4. Newspaper Characteristics 9.5. Characteristics of the Cartoons in the Cases 9.6. Reputation 9.6.1. National Reputation Before the Crisis 9.6.2. Abrupt Changes in the Organization’s Image 9.7. Crisis Communication 9.7.1. Communication Strategy for Managing the Reputational Crisis 9.7.2. Goals and Analysis of the Undertaken Crisis Communication 9.7.3. Evaluating the Reaction in Terms of National Image Restoration 9.7.4. Post‐Crisis Solutions 9.8. Reputational Ingredients: Presentation, Behavior, Communication 9.9. Implications 9.10. Conclusion 10. REPUTATIONAL ASPECTS OF TERRORIST CRISES. Kalin Kalinov 10.1. Recent Data on Terrorist Attacks Worldwide 10.2. Methodology of the Research of the Cases: Manchester 2017 and Charlie Hebdo 2015 10.3. Crisis Analysis: Manchester 2017 10.4. Crisis Analysis: Charlie Hebdo 2015 10.5. Conclusion 11. REPUTATIONAL CRISES IN TOURISM: SPECIFICS AND FEATURES. Hristina Slavova and Kalin Kalinov 11.1. Stability, Crises and Reputation in Tourism 11.2. Basics of Tourism Crisis Communication 11.3. Methodology and Definition of Reputational Crises in Tourism 11.4. Crisis Analysis: Brexit 11.5. Crisis Analysis: The Greek Debt Crisis 11.6. Comparative Analysis of the Crises in the British and Greek Tourism 11.7. Conclusion 12. REPUTATION CRISIS OF STATE INSTITUTIONS IN THE SECURITY SECTOR IN BULGARIA – THE REFUGEE CRISIS AS A TRIGGERING EVENT. Boyan Georgiev 12.1. The European Refugee Crisis (2011‐2015) as Research Object 12.2. Importance of Refugee Crises 12.2.1. Importance of the Crises for Bulgaria (2013–2015) 12.2.2. Reputational Importance of the Crises 12.2.3. Importance of the Crises for Government Communication in the Field of Security 12.3. Reputational Crises Triggered by the Refugees Issue 12.4. Research Methodology 12.5. Measuring the Crises in Phase A (July – December 2013) and Phase B (March 2014 – March 2015) 12.6. Comparative Analysis of the Two Cases 12.7. Key Variables in Both Cases 12.8. Crisis Communication in Both Cases 12.9. Evaluation of the Organization’s Response 12.10. Communication Strategy for Managing Reputational Crisis 12.11. Reputation Building Prior to the Crisis 12.12. Sudden Changes in the Image of Bulgaria 12.13. Factors Impacting the Reputation of the Researched State 12.14. Reputational Ingredients. Presentation, Behavior, Communication 12.15. Implications from the Research Goals 12.16. Conclusion 13. THE #DANSWITHME PROTESTS AS THE BEGINNING OF THE INSTITUTIONAL REPUTATION CRISIS IN BULGARIA. MODEL OF MEDIA IMPACT IN CRISES. Ina Bacheva 13.1. Introduction 13.2. Methodology and Concepts 13.3. Case Study: Mass Protests of 2013 – “Let’s Set the Monopolies on Fire” and “DANSwithme” 13.4. Protests #DANSwithme in 2013 and the Political Crisis in Bulgaria 13.5. The New Communication Environment and the Place of the Media. Influence Model 13.6. Classification of the Influence of Journalistic Tactics in Crisis Reporting 13.7. Model of Media Influence 13.8. Measuring the Crisis with the Appointment of Delyan Peevski as an Argument for Media Influence 13.9. Implications 13.10. Conclusion CONCLUSION BIBLIOGRAPHY SUMMAR

Prophylactic Central Neck Lymph Node Dissection Adds No Short-Term Benefit to Total Thyroidectomy for Differentiated Thyroid Cancer

Background and Objectives: To answer the research question: “Is prophylactic central neck lymph node dissection (pCNLD) beneficial among differentiated thyroid carcinoma (DTC) patients?” Materials and Methods: This was a retrospective cohort study enrolling DTC patients treated at the University Hospital Kaspela, Bulgaria, from 30 January 2019 to October 2021. The predictor variable was presence of pCNLD (total thyroidectomy with vs. without pCNLD). The main outcome variables were postoperative complications (i.e., vocal cord paralysis, hypoparathyroidism, postoperative bleeding, and adjacent organ injury) and recurrence parameters. Appropriate statistics were computed with the significant level at p ≤ 0.05. Results: During the study period, 300 DTC patients (59.7% with pCNLD; 79.3% females) with an average age of 52 ± 2.8 years were treated. The mean follow-up period of the entire cohort was 45.8 ± 19.1 months. On bivariate analyses, TT with pCNLD, when compared to TT alone, required longer surgical time (mean difference: 9.4 min), caused nearly similar complications (except transient hypothyroidism: p = 0.04; relative risk, 1.32; 95% confidence interval, 1.0 to 1.73), and no significantly different recurrence events, time to recurrence, and recurrent sites. The benefit–risk analyses using the number needed to treat and to harm (NNT; NNH) also confirmed that TT plus pCNLD was not very beneficial in DTC management. Conclusion: The results of this study refute the benefit of pCNLD in DTC patient care with TT. Further well-designed studies in a larger cohort with a longer follow-up period are required to confirm this conclusion

Reputational Crisis Management: Co-authors monograph

International audienceКолективната монография „Управление на репутационни кризи” обобщава научните резултати от изследванията в докторската програма по медии и комуникации на Софийския университет в дисциплините „Кризисен мениджмънт – управление на репутационни кризи” и „Кризисен пъблик рилейшънс”, ръководени от проф. д-р Чавдар Христов. Включва следните аспекти: Организационна репутация; Глобализация на репутационните кризи; Алгоритъм за измерване на репутационни кризи; Методологична рамка на изследването на казуси (case studies); Управление на репутация, рискове и кризи; Управление на репутацията чрез жизнения цикъл на риска; Слуховете – външна заплаха за репутационна криза; Троловете и хакерите – външни заплахи за репутационна криза; Компютърните вируси и организационната репутация; Политическата карикатура и глобалните репутационни кризи; Репутационни аспекти на терористичните кризи; Репутационните кризи в туризма – „Брекзит” и гръцката финансова криза; Репутационна криза на държавните институции в България – бежанската криза; Репутационна криза на политическата власт в България – протестите #ДАНСwithme.Table of Contents PREFACE 1. ORGANIZATIONAL REPUTATION: COMMUNICATION AND MANAGEMENT ASPECTS. GLOBALIZATION OF REPUTATIONAL CRISES. Chavdar Hristov 1.1. Defining Organizational Reputation 1.2. Reputation from the Perspective of Mass Perceptions and Behavior 1.3. Reputation in Relation to the Corporate Image and Brand 1.4. Reputation as Added Value 1.5. Reputation as Unity between Presentation, Behavior and Communication 1.6. Managerial Aspects of Organizational Reputation 1.7. Globalization and Reputational Crises: Digitalization and Information Leaks 2. REAL, MEDIA‐REPORTED AND REPUTATIONAL CRISES. CRISIS MEASUREMENT. Chavdar Hristov 2.1. Real, Media‐Reported and Reputational Crises 2.2. Algorithm for Measurement and Analysis of Reputational Crises 2.3. Measuring and Investigating Crisis Situations 2.4. Conclusions and Implications 3. METHODOLOGICAL FRAMEWORK. Chavdar Hristov and Kalin Kalinov 3.1. Why case studies? 3.2. Research Design 3.3. Research Protocol 3.4. Validity Indicators 4. MANAGING REPUTATION, RISKS AND CRISES. THE FOUR CATEGORIES OF REPUTATIONAL RISKS AND GUIDELINES FOR THEIR MANAGEMENT. Petar Kardzhilov 4.1. The Term “Reputation” 4.2. Four Aspects of the Reputation Strategy 4.3. Contemporary Challenges in Reputation Management 4.4. Problem Management and Crisis Management 4.5. Four Categories of Reputational Risks 4.6. Guidelines for Managing Different Categoriesof Reputational Risks 4.7. Interconnected Risks 4.8. The Nuclear Disaster in Fukushima 4.9. Conclusion 5. MANAGING REPUTATION THROUGH THE LIFE CYCLE OF RISK. PREDICTING, PREVENTING AND RESOLVING REPUTATIONAL RISK. Petar Kardzhilov 5.1. Life Cycle of the Reputational Risk 5.2. Predicting Reputational Risks 5.2.1. External Radar for Reputational Risks and Horizon Scanning 5.2.2. Internal Radar for Reputational Risks 5.2.3. Risk Analysis 5.2.4. Evaluating Reputational Risk 5.3. Preventing Reputational Risks 5.3.1. Architecture of Reputational Risk Management – “Hard” Intervention for Reputational Risks Prevention 5.3.2. Reputational Behavior, Leadership and Training – “Soft” Intervention for Reputational Risk Prevention 5.3.3. Organizational Social Responsibility (Corporate Citizenship) 5.4. Solving Reputational Risks 5.5. Conclusion 6. RUMOURS AS AN EXTERNAL THREAT, LEADING TO REPUTATIONAL CRISES. Plamen Atanasov 6.1. Defining Rumor 6.2. Are Fake News a Rumor 6.3. Rumor from the Reputation Building Perspective 6.4. Rumor and Reputational Crises 6.5. Rumor and Intangible Assets 6.6. Rumors in the Cyberspace Extended Communication 6.7. Conclusion 7. TROLLS AND HACKERS‐ EXTERNAL THREATS LEADING TO REPUTATIONAL CRISES. Plamen Atanasov 7.1. Defining Hackers and Trolls or Why the Rumor, Hackers and Trolls are Major Threats for the Reputation in the Modern World 7.2. Correlating Hackers’ and Trolls’ Actions with Reputational Crises 7.3. Conclusion 8. COMPUTER VIRUSES AND WHY THE ORGANISATION REPUTATION SUFFERS. Plamen Atanasov 8.1. Defining Computer Viruses 8.2. Viruses from the Reputation Management Perspective 8.3. Protecting the Organizational Reputation from Virus Damage 8.4. Conclusion 9. THE IMPACT OF THE POLITICAL CARTOON ON GLOBAL REPUTATION CRISIS. Boyan Georgiev 9.1. Theoretical Framework and Methodology 9.2. Presenting the Cases of the Danish Newspaper “Jyllands‐Posten” and the French Weekly “Charlie Hebdo” 9.3. Key Variables Impacting the Development of the Crisis 9.4. Newspaper Characteristics 9.5. Characteristics of the Cartoons in the Cases 9.6. Reputation 9.6.1. National Reputation Before the Crisis 9.6.2. Abrupt Changes in the Organization’s Image 9.7. Crisis Communication 9.7.1. Communication Strategy for Managing the Reputational Crisis 9.7.2. Goals and Analysis of the Undertaken Crisis Communication 9.7.3. Evaluating the Reaction in Terms of National Image Restoration 9.7.4. Post‐Crisis Solutions 9.8. Reputational Ingredients: Presentation, Behavior, Communication 9.9. Implications 9.10. Conclusion 10. REPUTATIONAL ASPECTS OF TERRORIST CRISES. Kalin Kalinov 10.1. Recent Data on Terrorist Attacks Worldwide 10.2. Methodology of the Research of the Cases: Manchester 2017 and Charlie Hebdo 2015 10.3. Crisis Analysis: Manchester 2017 10.4. Crisis Analysis: Charlie Hebdo 2015 10.5. Conclusion 11. REPUTATIONAL CRISES IN TOURISM: SPECIFICS AND FEATURES. Hristina Slavova and Kalin Kalinov 11.1. Stability, Crises and Reputation in Tourism 11.2. Basics of Tourism Crisis Communication 11.3. Methodology and Definition of Reputational Crises in Tourism 11.4. Crisis Analysis: Brexit 11.5. Crisis Analysis: The Greek Debt Crisis 11.6. Comparative Analysis of the Crises in the British and Greek Tourism 11.7. Conclusion 12. REPUTATION CRISIS OF STATE INSTITUTIONS IN THE SECURITY SECTOR IN BULGARIA – THE REFUGEE CRISIS AS A TRIGGERING EVENT. Boyan Georgiev 12.1. The European Refugee Crisis (2011‐2015) as Research Object 12.2. Importance of Refugee Crises 12.2.1. Importance of the Crises for Bulgaria (2013–2015) 12.2.2. Reputational Importance of the Crises 12.2.3. Importance of the Crises for Government Communication in the Field of Security 12.3. Reputational Crises Triggered by the Refugees Issue 12.4. Research Methodology 12.5. Measuring the Crises in Phase A (July – December 2013) and Phase B (March 2014 – March 2015) 12.6. Comparative Analysis of the Two Cases 12.7. Key Variables in Both Cases 12.8. Crisis Communication in Both Cases 12.9. Evaluation of the Organization’s Response 12.10. Communication Strategy for Managing Reputational Crisis 12.11. Reputation Building Prior to the Crisis 12.12. Sudden Changes in the Image of Bulgaria 12.13. Factors Impacting the Reputation of the Researched State 12.14. Reputational Ingredients. Presentation, Behavior, Communication 12.15. Implications from the Research Goals 12.16. Conclusion 13. THE #DANSWITHME PROTESTS AS THE BEGINNING OF THE INSTITUTIONAL REPUTATION CRISIS IN BULGARIA. MODEL OF MEDIA IMPACT IN CRISES. Ina Bacheva 13.1. Introduction 13.2. Methodology and Concepts 13.3. Case Study: Mass Protests of 2013 – “Let’s Set the Monopolies on Fire” and “DANSwithme” 13.4. Protests #DANSwithme in 2013 and the Political Crisis in Bulgaria 13.5. The New Communication Environment and the Place of the Media. Influence Model 13.6. Classification of the Influence of Journalistic Tactics in Crisis Reporting 13.7. Model of Media Influence 13.8. Measuring the Crisis with the Appointment of Delyan Peevski as an Argument for Media Influence 13.9. Implications 13.10. Conclusion CONCLUSION BIBLIOGRAPHY SUMMAR

Diagnosis and treatment of liver abscesses

Pyogenic abscesses are rare and difficult problem for modern surgery because of the high mortality rate. After the 70s of the last century the introduction of new image methods as ultrasound diagnostics, percutaneous and direct cholangiography and biliary drainage, guided aspiration, and percutaneous drainage of the abscess cavity dramatically changed both the diagnosis and treatment of these patients. The routine diagnostic methods are ultrasound and CT scan. Percutaneous aspiration and drainage under ultrasound or CT control is applied as first-line treatment of hepatic abscesses.Scripta Scientifica Medica 2008; 40(2): 137-139