AirTicket Sales as Bids from Airline Alliances

Motivated by the higher price sensitivity and service homogenisation in the airline industry in recent years, we propose a new methodology to deal with transaction prices and to estimate the effect of alliances in the US domestic market. The assumption that airlines compete on price allows us to take advantage of the observational equivalence between Bertrand competition and the reverse English auction. We then apply an MLE method, developed by Paarsch (1997) for esti- mating auctions, to recover the distributional characteristics of air fares using a sample of airline tickets from the US domestic market. This procedure allows us to benefit from the heterogeneity of individual prices while most studies have used average prices, which would have involved a loss of information and a potential bias. We find that an alliance operating in a market is associated with prices on average 18.9 percent higher. Additionally, we find the standard deviation of ticket prices to be 4.3 percent higher, which is likely related to more efficient revenue management practice by alliance partners operating together in the same market

Ядливи насекоми - новa алтернативa на месото: обзор

Nowadays, the challenge of finding food capable of meeting the needs of the population in terms of availability, nutritional value and sustainability is not only a necessity, but also an aspiration for a healthier lifestyle. The replacement of vertebrate animal products with new protein sources in human nutrition is a topic of increasing interest. Many studies have shown that insects, as a possible food source, have great potential to be called the "food of the future" because they are rich in high-quality proteins, fiber and fatty acids, mineral elements, vitamins.В днешно време предизвикателството за търсене на храна, способна да задоволи нуждите на населението по отношение на наличност, хранителна стойност и устойчивост, е не само необходимост, но и стремеж към по-здравословен начин на живот. Замяната на животински продукти с нови източници на протеини в храненето на човека е тема с нарастващ интерес. Много изследвания показват, че насекомите, като възможен хранителен източник, имат голям потенциал да бъдат наречени „храна на бъдещето“, тъй като те са богати на висококачествени протеини, фибри и мастни киселини, минерални елементи, витамини

Essays in Empirical Industrial Organization

Le résumé en français n'a pas été communiqué par l'auteur.In the past couple of decades, digitization has affected the strategy of economic players and the structure of markets across the board by lowering the cost of storing, sharing and analyzing data. This has given rise to a new field of economics, the economics of digitization, which touches upon the fields of industrial organization, market design, information economics, and labor economics. For industrial economists, these new questions and challenges coupled with new types of data, have led to vigorous research on the topics of reputation, search, rankings, matching, and online auctions. Following this line of research, the first two of the chapters in my thesis are on the topics information frictions and reputation systems in online service markets, and the third chapter proposes a novel methodology for modeling transaction prices motivated by competition on online distribution channels

PHOTOSYNTHESIS OF VEGETABLES AND FIELD PLANTS IN RESPONSE TO BIOCHAR TREATMENT

The requirements of modern agriculture include besides obtaining maximum yields of crops also maintaining and improving soil fertility and environmental protection. In recent years, interest of usage solid phase (charcoal or biochar) obtained by pyrolysis as soil improver, increases. Biochar is a solid material obtained from the thermo chemical conversion of biomass in anoxygen-limited environment. Additions of biochar to soil have generally been shown to be beneficial for growing crops. From an agronomic perspective it is suggested that biochar could improve soil health by increasing nutrient retention. The present pot experiment was conducted to investigate the effect of biochar application on the plants photosynthetic activity. The experiment was carrying out on two soil types, treated with different BC ratio. The plants grown on cinnamic pseudopozolic soil show a high content of plastid pigments in comparison with these on alluvial meadow soil. The aim of study is to evaluate the biochar agronomic impact on the plants growth, development and quality indicators

Essays in Empirical Industrial Organization

Le résumé en français n'a pas été communiqué par l'auteur.In the past couple of decades, digitization has affected the strategy of economic players and the structure of markets across the board by lowering the cost of storing, sharing and analyzing data. This has given rise to a new field of economics, the economics of digitization, which touches upon the fields of industrial organization, market design, information economics, and labor economics. For industrial economists, these new questions and challenges coupled with new types of data, have led to vigorous research on the topics of reputation, search, rankings, matching, and online auctions. Following this line of research, the first two of the chapters in my thesis are on the topics information frictions and reputation systems in online service markets, and the third chapter proposes a novel methodology for modeling transaction prices motivated by competition on online distribution channels

Thromboembolism in Renal Diseases

Patients with renal diseases are prone to both thrombosis and bleeding, as they have profound changes in all three classic components of coagulation, defined approximately 150 years ago by Virchow: blood flow, vessel wall (endothelial injury), and coagulation properties of the blood (e.g., coagulation and fibrinolytic systems and platelets). The prothrombotic state in chronic kidney disease (CKD), glomerular diseases (including systemic lupus and vasculitis), and some less frequent conditions (idiopathic retroperitoneal fibrosis, antiphospholipid syndrome, hemolytic‐uremic syndrome, etc.) is associated with vascular endothelial damage, increase in certain coagulation and antifibrinolytic factors, decrease in anticoagulation proteins, dyslipidemia, hypoalbuminemia, changes in platelet membranes, hemo‐ and peritoneal dialysis and heparin treatment, increased microRNAs and circulating microparticles, antiphospholipid antibodies, nephrotic syndrome, anemia with high platelet count, and so on. Nevertheless, the same patients have substantially increased risk of bleeding due to platelet dysfunction and intake of certain medications (antiaggregants, heparin and low‐molecular weight heparins, and anemia). The aim of this review is to present the main thrombo‐embolic risk factors in a wide variety of patients with renal diseases, including chronic glomerulonephritis (primary and secondary), chronic renal disease, and idiopathic retroperitoneal fibrosis. We have evaluated the risk factors for arterial and venous thromboses in a wide variety of renal patients with both glomerular and non‐glomerular diseases, including the presence of nephrotic syndrome, inborn and acquired coagulation defects (i.e., factor V Leiden, MTHFR gene mutation, 20210 prothrombin gene mutation, and antiphospholipid antibodies), corticosteroid treatment, and dyslipidemia. We are describing the results of these investigations and suggesting prophylactic anticoagulant strategies in such patients. Multiple risk factors influence the coagulation system in renal disease leading to both hypercoagulation and hemorrhagic diathesis. Therefore, renal patients should be thoroughly investigated for coagulation abnormalities, especially if pathogenic (i.e., corticosteroid and immunosuppressive) and anticoagulation treatment is to be initiated. Moreover, the doses of anticoagulant/antiaggregant and hemostatic medications should be considered carefully, having in mind the underlying diseases and risk factors, renal function, and concomitant treatment

Comparative study of in vitro, ex vitro and in vivo grown plants of Arnica montana – polyphenols and free radical scavenging activity

Arnica montana L. is an endangered species rich in sesquiterpene lactones, phenolic acids and flavonoids with high pharmaceutical value. The polyphenolic content and free radical scavenging activity of plants that had passed all stages of cultivation: micropropagation and rooting (in vitro), adaptation in greenhouse (ex vitro) and mountain conditions (in vivo) were evaluated. Four surface flavonoid aglycones [scutellarein 6-methyl ether (hispidulin), scutellarein 6,4’-dimethyl ether (pectolinarigenin), 6-OH luteolin 6-methyl ether and kempferol-6-methyl ether] were detected in the acetone exudates of the studied samples by means of thin layer chromatography.No differences in the accumulation of surface flavonoids were found among the tested leaf extracts of in vitro, ex vitro and in vivo samples. However, the extracts from the flowers were richer in surface flavonoids than extracts from the leaves. The methanol extracts of the samples from ex vitro and in vivo grown A. montana plants had significantly higher radical scavenging activity and polyphenolic content than the extracts of in vitro samples. The observed differences in the contents of these biologically active compounds were related to different growth conditions and stages of plant development. The biotechnological method of A. montana established holds promise for the future production of antioxidants

ESTABLISHING PHYSICAL ACTIVITY OF 3RD – 4TH – GRADERS WITH ACCELEROMETERS

Adolescents’ physical activity is and must be an essential part of their daily routine for proper and balanced growth and development. The use of accelerometry, a method that records the motor activity time spent in a lying or sitting position over twenty-four hours, is well-known. The actual data about a person’s movements enables us to be accurate and even to analyze the quantity and quality of those movements. We examined 135 children (mean age 129 months) with accelerometers Axivity model AX3, positioned around the wrist around the non-dominant arm. Based on consults, we established average values per twenty-four hours, namely – an average of 38.32% of the time children spent in a sitting position, 6.41% (92 min) they were engaged in a low activity, 15.42% (222 min - in a moderate activity, 1.79% (26 min) – in a high activity; and 38.06% of the time they spent sleeping. We found a weak correlation dependence r = -.263 (95%) between the body fat and the duration of the time spent in high activity

Influence of Kinesitherapy on Functional Independence in Patients with Supratentorial Unilateral Stroke in Chronic Period

Aim: The aim of the study is to evaluate the effect of the specialized kinesitherapeutic (KT) methodology (SKTM) on functional independence in patients with supratentorial unilateral stroke in the chronic period (SUSChP). Material and Methods: The study was conducted with 67 patients with SUSChP (56 patients included in the experimental group - 32 men and 24 women, with duration of the disease 7.8 ± 2.0 months, and 11 patients in the control group - 9 men and 2 women, with duration of the disease 7.3 ± 1.5 months). To evaluate the changes in functional independence, test for Functional Independence Measure (FIM) was used. Patients in the experimental group were treated with a specialized 10-day KT, which later continued to be performed as an adapted exercise program at home for a period of one month. Control patients perform a regular 10-day KT. This was done using SKTM principles of modern neurorehabilitation and motor learning as opposed to usual kinesitherapy. Results: After applying SKTM, the highest trend towards the improvement of functional independence was established after the 1st month with a level of significance during treatment p<0.001. Conclusion: In conclusion, the enclosed SKTM in the experimental group continued later as an adapted exercise program at home. It significantly improves the functional independence in patients with supratentorial unilateral stroke in the chronic period (SUSChP) compared  with the usual kinesitherapeutic methodology applied in the control group

Airline cooperation effects on airfare distribution: an auction-model-based approach

Airline alliances have a long history yet there is no academic consensus on how they affect price levels and their impact on price dispersion has not yet been studied. We address this question using a novel methodology motivated by the service homogenization and increased price competiton in this industry in the recent years. Establishing an equivalence between the online sales process and a reverse English auction, we use methods from auction econometrics to work in a new way with the standard industry data set: using individual ticket sales where only aggregated prices have been used in the past. Applicable to other industries where sellers compete in prices, this approach allows us to reconsider the effect of airline alliances on the distribution of airfares in the US domestic market. We find lower price mean and dispersion in markets where airlines belong to an alliance as a result of the lower variability of costs. The methodology we apply here can be used to study any distribution of individualized prices, which are now prevalent since the advent of the digital economy