Single-leg airline revenue management with overbooking

Airline revenue management is about identifying the maximum revenue seat allocation policies. Since a major loss in revenue results from cancellations and no-show passengers, over the years overbooking has received a significant attention in the literature. In this study, we propose new models for static and dynamic single-leg overbooking problems. In the static case, we introduce computationally tractable models that give upper and lower bounds for the optimal expected revenue. In the dynamic case, we propose a new dynamic programming model, which is based on two streams of arrivals. The first stream corresponds to the booking requests and the second stream represents the cancellations. We also conduct simulation experiments to illustrate the proposed models and the solution methods

SARS-CoV-2’ye Karşı Doğal Terapötiklerin Potansiyeli: Fenolik Bileşikler ve Terpenler

2019 yılının sonlarında Çin’de ortaya çıkan şiddetli, koronavirüs akut solunum yolu sendromu-koronavirüs-2’nin (SARS-CoV-2) neden olduğu koronavirüs hastalığı-2019, insan yaşamının hemen hemen her sektörünü etkileyen ve dünya ekonomisine büyük zarar veren benzeri görülmemiş bir küresel sağlık krizi meydana getirmiştir. SARS-CoV-2, yalnızca üst solunum yolu enfeksiyonuna neden olmakla kalmayıp aynı zamanda alt solunum yolu mukozası tutulumu da yapabilen ve bu sebeple pnömoniye neden olarak bazı hastalarda ölüme yol açan viral bir solunum yolu virüsüdür. Şu anda SARS-CoV-2 tedavisi için kanıtlanmış bir ilaç olmaması ile birlikte, tedavi için birçok kimyasal ve doğal aktif bileşik araştırmacılar tarafından test edilmiştir. Bu bitkisel bazlı antiviraller, daha az toksik oldukları ve enfeksiyöz mikroorganizmalar tarafından direnç geliştirilmesi daha düşük olasılıklı olduğu için birçok araştırmanın konusu olmuştur. Doğal terapötiklerin viral replikasyonu engellediği de birçok çalışmada bildirilmiştir. Bu derlemede, antiviral aktiviteye sahip olduğu bilinen doğal terapötikler olan fenolik bileşikler ve terpenler, SARS-CoV-2 tedavisinde kullanım potansiyelleri açısından ele alınmıştır

Biofortification and Localization of Zinc in Wheat Grain

Zinc (Zn) deficiency associated with low dietary intake is a well-documented public health problem, resulting in serious health and socioeconomic problems. Field experiments were conducted with wheat to test the role of both soil and foliar application of ZnSO4 in Zn concentration of whole grain and grain fractions (e.g., bran, embryo and endosperm) in 3 locations. Foliar application of ZnSO4 was realized at different growth stages (e.g., stem elongation, boot, milk, dough stages) to study the effect of timing of foliar Zn application on grain Zn concentration. The rate of foliar Zn application at each growth stage was 4 kg of ZnSO4 3 7H2O ha-1. Laser ablation (LA)-ICP-MS was used to follow the localization of Zn within grain. Soil Zn application at a rate of 50 kg of ZnSO4 3 7H2O ha-1 was effective in increasing grain Zn concentration in the Zn-deficient location, but not in the locations without soil Zn deficiency. In all locations, foliar application of Zn significantly increased Zn concentration in whole grain and in each grain fraction, particularly in the case of high soil N fertilization. In Zn-deficient location, grain Zn concentration increased from 11 mg kg-1 to 22 mg kg-1 with foliar Zn application and to 27 mg kg-1 with a combined application of ZnSO4 to soil and foliar. In locations without soil Zn deficiency, combination of high N application with two times foliar Zn application (e.g., at the booting and milk stages) increased grain Zn concentration, on average, from 28 mg kg-1 to 58 mg kg-1. Both ICP-OES and LA-ICP-MS data showed that the increase in Zn concentration of whole grain and grain fractions was pronounced when Zn was sprayed at the late growth stage (e.g., milk and dough). LA-ICP-MS data also indicated that Zn was transported into endosperm through the crease phloem. To our knowledge, this is the first study to show that the timing of foliar Zn application is of great importance in increasing grain Zn in wheat, especially in the endosperm part that is the predominant grain fraction consumed in many countries. Providing a large pool of Zn in vegetative tissues during the grain filling (e.g., via foliar Zn spray) is an important practice to increase grain Zn and contribute to human nutritio

Análisis mediante elíptica de Fourier y multivariante para diferenciar tamaño y forma de cultivos de nogal (Juglans regia L.)

Size and shape data of agricultural crops provide great sources for food processing technologies. The physical attributes of different fruits should be known for the design, developing and innovation of food technologies. In this study, the size and shape distinctions of fifteen national and international walnut cultivars (Midland, Sütyemez-1, Serr, Maraş-18, Maraş-12, Sütyemez-2, Kaman-1, Kaman-5, Pedro, Howard, Chandler, Şebin, Şen-2, Bilecik and KR-1) were determined using elliptic Fourier and multivariate approaches. Firstly, the gravitational features of walnut cultivars were determined, and their dimensional, area and shape attributes were revealed by image processing. Cluster analysis was used to designate the walnut cultivars. Elliptic Fourier descriptors obtained from walnut outlines provided the comparisons among walnut cultivars in shape. The shape index indicated that Serr, Sütyemez-2, Midland and Şen-2 cultivars were oval-shaped, and the others were spherical. The cluster analysis divided the walnut cultivars into four subgroups. Elliptic Fourier descriptors perfectly distinguished the walnut cultivars according to shape.Los datos de tamaño y forma de los cultivos agrícolas proporcionan grandes fuentes para las tecnologías de procesamiento de alimentos. Los atributos físicos de diferentes frutas deben conocerse para el diseño, desarrollo e innovación de tecnologías alimentarias. En este estudio, las diferencias de tamaño y forma de quince cultivares de nueces nacionales e internacionales (Midland, Sütyemez-1, Serr, Maraş-18, Maraş-12, Sütyemez-2, Kaman-1, Kaman-5, Pedro, Howard, Chandler, Şebin, Şen-2, Bilecik y KR-1) se realizaron mediante elípticas de Fourier y multivariantes. En primer lugar, se determinaron las características gravitacionales de los cultivares de nogal, y sus atributos dimensionales de área y de forma se revelaron mediante el procesamiento de imágenes. El análisis de clusters se utilizó para designar los cultivares de nueces. Los descriptores de elípticas de Fourier obtenidos a partir de contornos de nogal proporcionaron las comparaciones de formas entre los cultivares de nueces. El índice de forma indicó que los cultivares Serr, Sütyemez-2, Midland y Şen-2 tenían forma ovalada, y los otros eran esféricos. El análisis de conglomerados dividió los cultivares de nueces en cuatro subgrupos. Los descriptores de elípticas de Fourier distinguían de manera excelente las formas de las variedades de nueces

Returns to Foreign Language Skills in a Developing Country: The Case of Turkey

Foreign language skills represent a form of human capital that can be rewarded in the labor market. Drawing on data from the Adult Education Survey of 2007, this is the first study estimating returns to foreign language skills in Turkey. We contribute to the literature on the economic value of language knowledge, with a special focus on a country characterized by fast economic and social development. Although English is the most widely spoken foreign language in Turkey, we initially consider the economic value of different foreign languages among the employed males aged 25 to 65. We find positive and significant returns to proficiency in English and Russian, which increase with the level of competence. Knowledge of French and German also appears to be positively rewarded in the Turkish labor market, although their economic value seems mostly linked to an increased likelihood to hold specific occupations rather than increased earnings within occupations. Focusing on English, we also explore the heterogeneity in returns to different levels of proficiency by frequency of English use at work, birth-cohort, education, occupation and rural/urban location. The results are also robust to the endogenous specification of English language skills

Geometric control of universal hydrodynamic flow in a two dimensional electron fluid

Fluid dynamics is one of the cornerstones of modern physics and has recently found applications in the transport of electrons in solids. In most solids electron transport is dominated by extrinsic factors, such as sample geometry and scattering from impurities. However in the hydrodynamic regime Coulomb interactions transform the electron motion from independent particles to the collective motion of a viscous `electron fluid'. The fluid viscosity is an intrinsic property of the electron system, determined solely by the electron-electron interactions. Resolving the universal intrinsic viscosity is challenging, as it only affects the resistance through interactions with the sample boundaries, whose roughness is not only unknown but also varies from device to device. Here we eliminate all unknown parameters by fabricating samples with smooth sidewalls to achieve the perfect slip boundary condition, which has been elusive both in molecular fluids and electronic systems. We engineer the device geometry to create viscous dissipation and reveal the true intrinsic hydrodynamic properties of a 2D system. We observe a clear transition from ballistic to hydrodynamic electron motion, driven by both temperature and magnetic field. We directly measure the viscosity and electron-electron scattering lifetime (the Fermi quasiparticle lifetime) over a wide temperature range without fitting parameters, and show they have a strong dependence on electron density that cannot be explained by conventional theories based on the Random Phase Approximation

Psychosocial factors mediating the relationship between childhood emotional trauma and Internet gaming disorder: a pilot study

Internet gaming disorder (IGD) has been related to a wide range of detrimental psychological and health consequences. The purpose of the present pilot study was to test the direct and indirect relationships between IGD and emotional trauma, body image dissatisfaction, social anxiety, loneliness, depression, and self-esteem. A total of 242 online gamers completed a survey comprising a comprehensive battery of psychometric self-report scales concerning aforementioned variables. Results indicated that IGD was significantly correlated with all the variables except for body image dissatisfaction. Path analysis indicated an indirect relationship between childhood emotional trauma and IGD through depressive symptoms, while adjusting for gender, age, and number of hours gaming. The findings of the present study indicate that online gamers with a history of emotional abuse and/or neglect have higher levels of depressive symptoms, and that depressive symptoms are important risk factors of IGD

Turner syndrome and associated problems in turkish children: A multicenter study

Objective: Turner syndrome (TS) is a chromosomal disorder caused by complete or partial X chromosome monosomy that manifests various clinical features depending on the karyotype and on the genetic background of affected girls. This study aimed to systematically investigate the key clinical features of TS in relationship to karyotype in a large pediatric Turkish patient population. Methods: Our retrospective study included 842 karyotype-proven TS patients aged 0-18 years who were evaluated in 35 different centers in Turkey in the years 2013-2014. Results: The most common karyotype was 45,X (50.7%), followed by 45,X/46,XX (10.8%), 46,X,i(Xq) (10.1%) and 45,X/46,X,i(Xq) (9.5%). Mean age at diagnosis was 10.2±4.4 years. The most common presenting complaints were short stature and delayed puberty. Among patients diagnosed before age one year, the ratio of karyotype 45,X was significantly higher than that of other karyotype groups. Cardiac defects (bicuspid aortic valve, coarctation of the aorta and aortic stenosi) were the most common congenital anomalies, occurring in 25% of the TS cases. This was followed by urinary system anomalies (horseshoe kidney, double collector duct system and renal rotation) detected in 16.3%. Hashimoto’s thyroiditis was found in 11.1% of patients, gastrointestinal abnormalities in 8.9%, ear nose and throat problems in 22.6%, dermatologic problems in 21.8% and osteoporosis in 15.3%. Learning difficulties and/or psychosocial problems were encountered in 39.1%. Insulin resistance and impaired fasting glucose were detected in 3.4% and 2.2%, respectively. Dyslipidemia prevalence was 11.4%. Conclusion: This comprehensive study systematically evaluated the largest group of karyotype-proven TS girls to date. The karyotype distribution, congenital anomaly and comorbidity profile closely parallel that from other countries and support the need for close medical surveillance of these complex patients throughout their lifespan. © Journal of Clinical Research in Pediatric Endocrinology

Editorial of Special Issue of National Identities: Alevism as an ethno-religious identity: Contested boundaries

No abstract for editorial but this is the opening paragraph: This special issue on Alevism and trans/national Alevi identity critically engages with the relationship between religion, ethnicity and national identity. The core issues are as follows: • how ethnicity and religion are conceptualised for a relatively invisible ethnic group in different national contexts; • how religion and ethnicity intersect when Alevism is both a faith and an ethnic identity, especially when conceptions of that identity are contested; • how identity is shaped through state policies within different national policy contexts and how etic definitions of minority communities are constructed by the state or other agencies with the power to impose them on the community in contrast to the emic or self-definitions of Aleviness from within the Alevi community; • how despite the fragmented, heterogeneous nature of Alevi communities, there is also a sense of a single, transnational imaginary community, at least for the purposes of political assimilation/integration and activism; • how education and other arenas of political, religious and cultural engagement at local, national and transnational levels create the possibilities, both positively and negatively, for future action/policy to situate minority ethnic communities