Revenue management in airline operations : booking systems and aircraft maintenance services

Although the principles of Revenue Management (RM) have vaguely been used in business for a long time, an increasing number of organizations are implementing well structured RM systems in the last few decades due to the developments in science and technology, especially in economics, statistics, operations research and computer science. The improvements in information and telecommunication technologies, wide use of Internet, rise of e-commerce and successful supply chain management strategies have enabled organizations to model and solve complex RM problems. This dissertation research concentrates on airlines, the earliest and leading user of RM. Today, airlines face serious financial problems due to the increasing costs and competition. They continuously explore new opportunities especially in terms of RM to make profit and survive. In this study, two problems are analyzed within this scope; airline booking process with adapted options approach and aircraft maintenance order control through RM. First; a new approach, financial options approach, is proposed to sell tickets in airline reservation systems. The options are used to overcome the uncertainty in air travel demand and competitors' actions. The seat inventory control problem is formulated with overbooking and embedded options respectively. Then a simulation study is conducted the potential of using options in airlines booking process. Accordingly, empirical results show that they present an opportunity both to utilize capacity more efficiently and to value seats more precisely compared to overbooking approach. Secondly; a peak load pricing concept is applied for aircraft maintenance order control problem. Aircraft maintenance centers face with peak loads in some seasons and the capacity is underutilized in other seasons. A peak load pricing model is proposed to shift some of the price elastic demand from peak seasons to off-peak seasons to balance demand and supply around the year. A dynamic programming algorithm is developed to solve the model and a code is written in C++. Results show that the model improves both annual capacity loading factors and revenues without causing a discomfort from the perspective of the customers. The details of both studies are presented in this dissertation research. [PUBLICATION ABSTRACT

The relation of IgM deposition to clinical parameters and histomorphometry in childhood mesangial proliferative glomerulonephritis

We investigated the question of whether IgM deposition causes any difference in the histomorphometry of children with mesangial proliferative glomerulonephritis (MePGN)

Horseshoe kidney with mesangioproliferative glomerulonephritis and goiter

Horseshoe kidney is a relatively common renal anomaly with which many structural and developmental anomalies have been shown to be associated. However, there are only a few case reports regarding the association of membranous glomerulonephritis and focal sclerosing glomerulonephritis in patients with horseshoe kidneys. We report a girl who was evaluated for hematuria and proteinuria, and found to have horseshoe kidney. Renal biopsy demonstrated mesangioproliferative glomerulonephritis. She also had simple diffuse goiter

The relationship between common geriatric syndromes and potentially inappropriate medication use among older adults

Background/aim Polypharmacy and inappropriate medication use in older adults is a major public health problem associated with morbidity and mortality. Aging is associated with metabolic changes and decreased drug clearance, increased drug-drug interactions, prescribing cascades, and potentially inappropriate medication (PIM) use. The purpose of this study was to evaluate the association between a common geriatric syndromes and PIM use among older adults. Methods Study participants were recruited among patients admitted to Istanbul Medical School Geriatrics outpatient clinic between June 2000 and June 2014 and were evaluated retrospectively by a geriatrician using the patients' records according to Beers 2012 criteria. Results Among the 667 enrolled patients, 421 (63.1%) were women and 246 (36.9%) were men. The use of PIM was not associated with age or sex. Polypharmacy (OR 4.86, 95% CI 3.25-7.27, p < 0.001), malnutrition (OR 2.69, 95% CI 1.52-4.76, p = 0.001), depression (OR 2.61, 95% CI 1.7-3.95, p < 0.001), presence of fall in the previous year (OR 2.24, 95% CI 1.51-3.32, p < 0.001), and dementia (OR 1.69, 95% CI 1.08-2.65, p = 0.021) were independently associated with the use of PIM. Discussion/conclusions The results of our study suggest that PIM use is independently associated with presence of polypharmacy, malnutrition, depression, falls and dementia in older outpatients. Identifying the association of inappropriate medication use with common geriatric syndromes in older people can help to prevent, delay, and reduce PIM use and related adverse health outcomes

Antiphosphlipid Syndrome Presented with Renovascular Hypertension

Renovascular pathologies are one of the treatable causes of hypertension. Antiphospholipid syndrome develops owing to a heterogeneous group of antiphospholipid antibodies which causes various thrombotic problems. This entity may effects very small vessels and sometimes leads to hypertension. We present a 55-year-old female with unilateral renal artery stent implantation because of renovascular hypertension. After application, a re-stenosis developed and in-stent angioplasty was performed, but it was required a nephrectomy because of haemorrhage. Severe ischemic nephropathy was detected in the nephrectomy material. She was diagnosed with antiphospholipid syndrome. Prolonged prothrombin time with hemorrhagic diathesis which coexisting thrombosis responded steroid therapy. But in follow-up, the thrombocytopenia developed, the patient could not recieve anticoagulant therapy and died due to a pulmonary embolism-like syndrome. This case reminds, renovascular hypertension is one of the major reasons of secondary hypertension and antiphospholipid syndrome always should be considered in thrombotic processes.</p

Needs for drone education in Finland. University collaboration network drone survey summary report

In this survey summary report, we have highlighted the key outcomes of the survey conducted by the UCN-DRONE project (Project Number) funded by the Finnish Ministry of Education and Culture. The survey was conducted online in March 2022 and we received 177 respondents from several regions of Finnish territories

Is there a relationship between ACTN3 R577X gene polymorphism and sarcopenia?

Background and aims The alpha-actinin (ACTN) genes are important structural components of the sarcomere. Sarcopenia is a common geriatric syndrome characterized by morbidity and mortality. Our study aimed to examine the relationship between the ACTN3 R577X gene and sarcopenia in community-dwelling Turkish adults. Methods We designed a cross-sectional study among the patients aged >= 65 years admitted to the geriatric outpatient clinic. We recorded the general characteristics of the patients. We used the Jamar hand dynamometer to evaluate handgrip strength. Body composition was estimated using bioimpedance analysis. Sarcopenia was diagnosed according to the European Working Group on Sarcopenia in Older People2 criteria with population-specific cutoffs. We performed analyses of low muscle mass (LMM) with skeletal muscle mass index adjusted for body mass index [SMMI(BMI)]. We further categorized the SMMI(BMI) cutoffs into tenths. The analyzes were performed according to the 90th percentile SMMI(BMI) cutoffs. Peripheral blood samples were collected to determine the ACTN3 genotypes. Results 197 participants were included [mean age: 76.3 +/- 6.1 years, 151 (76.6%) women]. The proportions of the ACTN3 genotypes were as follows: RX (45.1%) > RR (31%) > XX (23.9%). The significant difference between genotypes was found only for low SMMI(BMI) according to the 90th percentile (p = 0.025). In multivariate analysis, only gender (female) was independently associated with LMM. Conclusion We did not find any association between ACTN3 R577X gene polymorphism and probable sarcopenia, confirmed sarcopenia and LMM. Besides, much more research is needed to reveal how ethnicity affects the muscles of older adults with ACTN3 R577X gene polymorphism