A comparative analysis of the air transport liberalization and global airline alliances on market concentration

As a leading aviation country in the world, the U.S. has open skies agreements with more than 120 countries around the world. In the last twenty years, the three global alliances – Oneworld, Star and Skyteam has grown in parallel with the increased air service liberalization. In 2019, these three global alliances carried about 44% of global passenger traffic, while earning about 66% of global airline revenue. The transatlantic market is highly concentrated among the three global alliances, having 80% of market share on the routes between the U.S. and Europe. Using the three alliances as focal groups, this paper will investigate market concentration on non-stop international routes to and from the U.S. under open-skies and non-open-skies agreements. The key research question addressed will be: whether and to what extent the growth of global alliances may lead open-skies routes to be less competitive as compared to those non-open-skies routes. Policy implications will be drawn and discussed based on the findings of the study

The impact of aircraft leasing strategy on fleet heterogeneity in the global airline industry

This project aims to analyze fleet heterogeneity and its relationship to airlines\u27 use of leasing strategies around the globe. Using data collected from Cirium, we develop Blau\u27s index of fleet heterogeneity for both aircraft frame and engine at the manufacturer, family, and model level, covering the top 200 passenger airlines worldwide. The study covers 18,808 in-service aircraft at an average age of 11 years, including 201 aircraft models and 247 different engine types. The average leasing rate is about 70% among the sample airlines. In this study, we will dive into the fleet composition between different manufacturers and their percentage distribution across regions such as Europe, Africa, Asia-Pacific, North America, and South America. In addition, we will compare the reliance on aircraft leasing by airlines in different regions and in adopting different business models. We will estimate the relationship between fleet heterogeneity and leasing strategy and test our hypothesis about the role played by leasing strategy in helping airlines diversify their fleet and expand their market share rapidly. The trend of low-cost carriers using a more standardized fleet will also be examined. The findings from our study will provide management implications for airlines and shed light on the importance of strategically integrating aircraft financing and fleet composition decisions

Brain network dynamics in deviance response and auditory perception

Neuronale Reaktionen auf plötzliche Veränderungen des sensorischen Inputs können in vielen Teilen der sensorischen Bahnen auf verschiedenen Organisationsebenen beobachtet werden. So können beispielsweise Abweichungen, die die Regelmäßigkeit auf verschiedenen Abstraktionsebenen verletzen, als einfache Ein-/Aus-Reaktionen einzelner Neuronen oder als kumulative Reaktionen neuronaler Populationen beobachtet werden. Aufgrund des relativ einheitlichen und selbstähnlichen Verdrahtungsmuster im Kortex scheint es unwahrscheinlich, dass die verschiedenen kortikalen Reaktionen, die unterschiedliche Funktionalitäten unterstützen (z.B. Lückenerkennung, Chunking, etc.), jeweils auf spezialisierten kortikalen Verschaltungsmustern beruhen. Darüber hinaus sprechen reziproke Verdrahtungsmuster (mit heterogenen Kombinationen von exzitatorischen und inhibitorischen Verbindungen) im Kortex für ein generisches Prinzip zur Erkennung von Abweichungen. Das vorgeschlagene generische Prinzip der Abweichungserkennung unterteilt die Erzeugung der Abweichungsreaktion in zwei Funktionsschritte: Regularitätsbildung und Änderungserkennung. Das Prinzip legt nahe, dass die im Kortex beobachteten Reaktionen, wie die kortikalen Ein/Aus-Antworten, die kortikale Auslassungsreaktion (OSR) und die Mismatch-Negativität (MMN), als Änderungsreaktionen auf verschiedenen Abstraktionsebenen betrachtet werden können. Das Netzwerkmodell, das auf diesem Prinzip basiert, reproduziert mehrere experimentell beobachtete Befunde, zu denen die unterschiedlichen zeitlichen Profile der Ein/Aus-Antworten, die lineare Beziehung zwischen OSR-Latenz und Input Stimulus Onset Asynchrony (SOA) und die langsamen und schnellen Reaktionen im Sequenz-MMN-Paradigma gehören. In Bezug auf die Erkennung von Veränderungen deuten die Simulationsergebnisse darauf hin, dass für das Auftreten von Veränderungsdetektoren ein Disinhibitionsmechanismus erforderlich ist. Eine Analyse der Verbindungsstärken im Netzwerk deutet weiterhin auf einen unterstützenden Effekt der synaptischen Anpassung und einen destruktiven Effekt von N-Methyl-D-Aspartat-Rezeptor- (NMDA-r)-Antagonisten auf die Änderungserkennung hin. In Bezug auf die Regularitätsbildung deuten die Simulationsergebnisse auf den Notwendigkeit für ein raumcodierenden Schema, eine größere Zeitkonstante der hemmenden Population und kurzfristige Plastizität hin, um eine stetige neuronale Repräsentation der Regularität zu unterstützen. Für die experimentelle Validierung können wir mehrere Vorhersagen aus dem Modell ableiten. Erstens sollten die verschiedenen kortikalen Abweichungsreaktionen ähnliche laminare Profile aufweisen, insbesondere bzgl. der Aktivität der inhibitorischen Neuronen, in denen die Änderungserkennung stattfindet. Zweitens würden die NMDA-r-Antagonisten im Allgemeinen die kortikale Aus-Reaktion, die kortikale OSR und die MMN dämpfen. Drittens könnte es unterschiedliche räumliche Verteilungen der Änderungserkennung und Regularitätsbildung geben, da die beiden Funktionen aus unterschiedlichen Netzwerkeigenschaften wie Zeitkonstanten und Verbindungsmustern entstehen. Diese Arbeit bietet einen neuen Blickwinkel auf die neuronalen Mechanismen, die der Detektion von Abweichungen zugrunde liegen. Zukünftige Forschungsthemen, wie der Aufmerksamkeitsmechanismus in der Wahrnehmung, die funktionelle Rolle verschiedener Arten von hemmenden Neuronen sowie höhere kognitive Funktionen wie Spracherwerb und -verständnis, können auf der aktuellen Implementierung des Modells basieren.Neural responses to sudden changes can be observed in many parts of the sensory pathways at different organizational levels. For example, deviants that violate regularity at various levels of abstraction can be observed as simple On/Off responses of individual neurons or as cumulative responses of neural populations. The cortical deviance-related responses supporting different functionalities (e.g., gap detection, chunking, etc.) seem unlikely to arise from different function-specific neural circuits, given the relatively uniform and self-similar wiring patterns across cortical areas and spatial scales. Additionally, reciprocal wiring patterns (with heterogeneous combinations of excitatory and inhibitory connections) in the cortex naturally speak in favor of a generic deviance detection principle. The proposed generic deviance detection principle separates the generation of deviance response into two functional stages: regularity formation and change detection. The principle suggests that the deviance-related responses observed in the cortex, such as the cortical On/Off responses, the cortical omitted-stimulus response (OSR), and the mismatch negativity (MMN), can be regarded as change responses at different levels of abstraction. The network model based on the principle reproduce several experimentally observed properties of cortical deviance-related responses, which include the diverse temporal profiles of On/Off responses, the linear relationship between OSR latency and input stimulus onset asynchrony (SOA), and the slow and fast responses in the sequence MMN paradigm. Regarding change detection, the simulation results suggest that the emergence of change detectors relies on the involvement of disinhibition. An analysis of network connection settings further suggests a supportive effect of synaptic adaptation and a destructive effect of N-methyl-D-aspartate receptor (NMDA-r) antagonists on change detection. Regarding regularity formation, the simulation results suggest the need for a place coding scheme, a larger time constant of inhibitory population, and short-term plasticity to support a steady neural representation of regularity. Several model predictions are provided for experimental validation. First, the cortical deviance-related responses might show similar laminar profiles, especially the activity of the inhibitory neurons where the change detection takes place. Second, the NMDA-r antagonists would generally dampen the cortical Off response, the cortical OSR, and the MMN. Third, there might be distinct geometric distributions of change detection and regularity formation, since the two functions emerge from different network properties such as the time constants and connection patterns. This thesis provides a new viewpoint on the neural mechanisms underlying the generation of deviance response. Future research topics, such as the attention mechanism in perception, the functional roles of various types of inhibitory neurons, and the process of higher cognitive functions such as language acquisition and comprehension, can be based on the current implementation of simulations

Precipitation Dynamics for the Formation of Nylon-6 Polyamide Membranes by Isothermal Precipitation in Water/Formic Acid Solutions

[[abstract]]The ternary mass transfer equations that describe the isothermal immersion process for polyamide membrane preparation were solved. To account for the moving boundary conditions, coordinate transformations were performed both for the membrane and the bath regions. Mutual diffusion coefficients between solvent and polymer were measured and used to derive ternary phenomenological coefficients for mass transfer equations. The calculated precipitation times, concentration profiles, and diffusion trajectories were found to agree with the measured light transmittance data and the membrane morphologies presented previously.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙

Septic Shock after Conservative Management for Placenta Accreta

SummaryObjectiveThe rate of placenta accreta has risen in the last three decades due to the increasing rate of cesarean section. Placenta accreta usually results in severe postpartum hemorrhage requiring massive blood transfusion and postpartum hysterectomy. Conservative treatment is an alternative in selected patients to preserve fertility and decrease postpartum hemorrhage, but the risks of conservative treatment have seldom been described.Case ReportA 39-year-old woman with placenta accreta diagnosed during cesarean section was treated conservatively. Persistent puerperal fever with leukocytosis developed during the postpartum period in spite of long-term antibiotic treatment. Evacuation of the retained placenta resulted in septic shock, which occurred immediately after dilatation and curettage. An uneventful recovery was achieved after use of strong antibiotics and fluid challenge.ConclusionAt present, there is no consensus about the optimal treatment for placenta accreta. Conservative treatment appears to be an alternative in selected patients, but the complications such as sepsis should be carefully identified and appropriately managed

Inhibition of Mitochondria- and Endoplasmic Reticulum Stress-Mediated Autophagy Augments Temozolomide-Induced Apoptosis in Glioma Cells

Autophagy is a crucial process for cells to maintain homeostasis and survival through degradation of cellular proteins and organelles, including mitochondria and endoplasmic reticula (ER). We previously demonstrated that temozolomide (TMZ), an alkylating agent for brain tumor chemotherapy, induced reactive oxygen species (ROS)/extracellular signal-regulated kinase (ERK)-mediated autophagy to protect glioma cells from apoptosis. In this study, we investigated the role of mitochondrial damage and ER stress in TMZ-induced cytotoxicity. Mitochondrial depolarization and mitochondrial permeability transition pore (MPTP) opening were observed as a prelude to TMZ-induced autophagy, and these were followed by the loss of mitochondrial mass. Electron transport chain (ETC) inhibitors, such as rotenone (a complex I inhibitor), sodium azide (a complex IV inhibitor), and oligomycin (a complex V inhibitor), or the MPTP inhibitor, cyclosporine A, decreased mitochondrial damage-mediated autophagy, and therefore increased TMZ-induced apoptosis. TMZ treatment triggered ER stress with increased expression of GADD153 and GRP78 proteins, and deceased pro-caspase 12 protein. ER stress consequently induced autophagy through c-Jun N-terminal kinases (JNK) and Ca2+ signaling pathways. Combination of TMZ with 4-phenylbutyrate (4-PBA), an ER stress inhibitor, augmented TMZ-induced cytotoxicity by inhibiting autophagy. Taken together, our data indicate that TMZ induced autophagy through mitochondrial damage- and ER stress-dependent mechanisms to protect glioma cells. This study provides evidence that agents targeting mitochondria or ER may be potential anticancer strategies

Factors affecting airliners\u27 decision of purchasing airplanes

Purchasing aircraft is one of the most critical actions in the functioning of airline companies. The emergence of more interconnected global economies and the expansion of international business operations have led to a steady increase in travel demand after the COVID-19 pandemic. Each aircraft purchase includes a sizable amount of money and consideration. With a clear plan, airline businesses can buy the ideal range of aircrafts for their size and operating requirements. However, if companies buy their fleet without a solid strategy, these expensive aircrafts will become a financial burden to the firms. In this paper, we compare Boeing and Airbus\u27s aircraft capabilities, technical support, and maintenance costs over the aircraft\u27s service life. Subsequently, we discuss the significant elements influencing airline firms\u27 purchasing practices. We conclude by projecting the global fleet market for the next 30 years and the factors that airlines should consider most when buying aircrafts. This paper can assist airlines and aircraft manufacturers in making effective decisions regarding their purchasing policies