Hub Status Research Articles

The effect of United States commercial airport rate-setting methods on airport bond ratings

PurposeA major source of external funding for US airports comes from issuing municipal bonds. Credit rating agencies evaluate the bonds using multiple factors, but the judgments behind the ratings are not well understood. This paper examines if airport rate-setting methods affect the bond ratings of US airports.Design/methodology/approachUsing a set of unbalanced panel data for 58 hub airports from 2010 to 2019, we examine the effect of the rate-setting methods and other airport characteristics on Fitch’s airport bond rating.FindingsWe find that compensatory airports consistently receive a very high bond rating from Fitch. The probability of getting a very high Fitch rating increases by ∼28 percentage points for a compensatory airport. Additionally, the probability of getting a very high rating is about 33 percentage points higher for a legacy hub.Research limitations/implicationsThe study uses Fitch bond ratings. Future studies could examine if S&P’s and Moody’s ratings are also influenced by airport rate-setting methods and legacy hub status.Practical implicationsThe results uncover the linkage between bond ratings and their determinants for US airports. This information is important for investors when assessing airport creditworthiness and for airport operators as they manage capital project financing.Originality/valueThis is the first study to evaluate the effects of rate-setting methods on airport bond rating and also the first to document a statistically significant relationship between airports’ legacy hub status and bond ratings.

Alterations in the hub structure of whole-brain functional networks in patients with drug-naïve schizophrenia: Insights from electroencephalography-based research.

This study aimed to identify atypical hubs in the whole-brain networks of patients with schizophrenia (SZ) and examine the effects of antipsychotic medications, using electroencephalography (EEG) data. We estimated the functional connectivity across all electrodes by applying the phase lag index to the EEG signals of 21 drug-naïve patients with SZ and 31 age-matched healthy controls. Betweenness centrality (BC), a measure of hub status, was calculated for each electrode and frequency band. Data from 14 patients were re-evaluated after initiating treatment with antipsychotic medications. BC values decreased significantly at the Fz site in the beta band, decreased significantly at Pz in the gamma band, and increased significantly at O1 in the gamma band among patients with SZ. These changes persisted after antipsychotic treatment and were unrelated to clinical symptoms. The abnormal hub topology we observed, especially in the high-frequency band, may reflect the pathophysiology of SZ, and this study highlights the utility of BC analysis of EEG data for detecting alterations in the whole-brain networks of patients with SZ.

Employment Trends in Northern Italy’s Medium-Sized Cities from 2012 to the Shock of the COVID-19 Pandemic: A Group of Cities in Distress?

In a globalised economy, metropolises seem to have an ‘extra gear’ compared to smaller urban centres: they attract the most skilled businesses, drive innovation in many fields and can count on material and immaterial assets that foster greater resilience to adverse events of various kinds. Against the dynamism of metropolises, which evolutionary paths do medium-sized cities (MSCs) follow? This paper focuses on the case of Northern Italy and explores employment trends between 2012 and 2020 in 189 MSCs with a population of between 20,000 and 200,000 inhabitants. The evolutionary trajectories of these cities and their varying specialisations are investigated over a period marked by a moderate recovery of the Italian economy following the Great Recession and by a further setback caused by the COVID-19 pandemic. In general, in terms of employment performance, the 189 cities in question were less dynamic than the metropolises, but it is nevertheless necessary to look at their individual circumstances in detail. Furthermore, this work shows significant differences between the MSCs of the Northwest and Northeast in terms of evolutionary trajectories and specialisation profiles. The most problematic situations also relate to cities with a hub status in the wider context and do not only concentrate where a production structure is present that is linked to industry.

Cross-subsidization and U.S. airports

Airports serve as a two-sided market where aeronautical and non-aeronautical operations are complementary. This interdependence means that an increase in aeronautical operations output results in a corresponding increase in non-aeronautical revenues. To retain existing airlines and attract new airline clients, airports should offer reasonable aeronautical fees, which can be subsidized by lucrative non-aeronautical revenues. This raises questions about whether cross-subsidization pricing strategies are used in the U.S. airport industry. To examine this issue, we analyzed data from 59 large and medium hub airports between 2009 and 2019, focusing on the relationship between marginal costs and fees of aeronautical and non-aeronautical operations. The marginal cost was estimated from a translog variable cost function by utilizing a seemingly unrelated regression model. Our study highlights the importance of considering the complex interplay between aeronautical and non-aeronautical operations at airports and the potential for cross-subsidization. We also examined the factors influencing cross-subsidization at airports. The results reveal that large airports are less likely to engage in cross-subsidization compared to their counterpart airports. On the other hand, given that the FAA's airport classification diverges from that in the hub-spoke system, we incorporated airports that serve as hubs for legacy airlines (American, United, and Delta) into our model to account for the influence of hub status. Our findings indicate that hub status does not influence cross-subsidization decisions. In addition, airports governed by local authorities place less emphasis on cross-subsidization whereas the presence of airport competition often incentivizes a more pronounced adoption of cross-subsidization practices. Airports in densely populated areas have diminished focus on cross-subsidization while there is a positive correlation between local GDP and cross-subsidization. Finally, cross-subsidization practices do not differ between airports dominated by LCCs and those without such dominance. Future research should focus on exploring the implications of these findings for the welfare of passengers and other stakeholders in the aviation industry.

Airborne flight time: A comparative analysis between the U.S. and China

Actual airborne time (AAT) is the time between actual wheels-off and actual wheels-on of a flight. Given the ever-growing demand for air travel and growing flight delays, understanding the behavior of AAT is increasingly important for on time performance and delay propagation. Of particular interest is the comparison on AAT in different countries with varying air route structures, air traffic management systems, weather, and geography. This paper performs the first comparative empirical analysis of AAT behavior, focusing on the U.S. and China. The focus is on how AAT is affected by origin-destination (OD) distance, the possible pressure to reduce AAT from other parts of flight operations, hub status of departure/arrival airports, enroute and terminal traffic conditions, and convective weather. Econometric models are developed to quantify the impacts of factors on AAT behavior in China and the U.S., separately. The estimation results show that in both countries AAT is highly correlated with OD distance. Flight time in China is longer than that in the U.S. given the same OD distance which indicates a low effective speed may be the result of a low aircraft speed, or due to the flight experiencing metering, rerouting, holding or vectoring in Chinese airspace. In addition, we find that a flight has limited capability to make up for pre-departure delay. Sensitivity analysis of AAT to flight length and aircraft utilization is further conducted. Given the more abundant civil airspace, flexible routing networks, and efficient air traffic flow management (ATFM) procedures, we performed a counterfactual analysis to investigate how Chinese AATs would change if they were governed by the U.S. model. We find that this would result in significant efficiency gains for the Chinese air traffic system. On average, 13 min of AAT per flight would be saved. Systemwide fuel saving would amount to 326 million gallons with CO2 emission reduction of 2.7 million tons and direct airline operating cost saving of over $1.3 billion in 2016.

Seasonal Characteristics of Agricultural Product Circulation Network: A Case Study in Beijing, China

Agricultural product circulation is an appropriate way to optimize the distribution of agricultural resources and maintain food safety. The seasonality of agriculture leads to seasonal variations in agricultural product circulation. Previous studies constructed origin–destination networks based on annual statistics to investigate the static structure of agricultural product circulation networks from a single view, failing to capture the seasonal and multi-dimensional characteristics in agricultural product circulation. This study presents a multi-view analytical framework used to investigate the seasonal characteristics of an agricultural product circulation network. First, agricultural product circulation networks in different seasons were constructed with mass freight trajectory data through trajectory mining technology. Then, the seasonal characteristics of agricultural product circulation were, respectively, analyzed from a macro-view (networks), meso-view (edges) and micro-view (nodes). A case study was conducted in Beijing, China. It is argued that: (1) The presented method for extracting agricultural trip chains based on massive freight trajectories is feasible for the construction of agricultural product circulation networks. (2) The agricultural product circulation networks in four seasons exhibit an obvious hierarchical and radial structure. South China has a higher network density in winter and spring, whereas northeast and northwest China are the opposite. (3) A total of 80% of the linkage strength is concentrated, on average, in 35.3% of city-pairs in four seasons, where the agglomeration effect and hub status of the linking cities is more prominent in summer and autumn. (4) A total of 316 cities form Beijing agricultural product circulation networks, 48.1% of which are mainly served by Beijing agricultural product circulation in winter and spring, which is 2.7 times more than cities served in summer and autumn. These findings extend the scientific understanding of the agricultural product supply chain from a dynamic and multi-dimensional view, which provides essential information for optimizing sustainable agri-food systems and ensuring food security.

Traffic accessibility analysis of major cities in the Yangtze River Delta under the integration of regional development

The Yangtze River Delta region is one of the regions with the highest economic development dynamics in China, and the importance of its transportation hub status is self-evident. This paper selects the indicator of traffic accessibility and adopts the weighted time cost method to analyze the traffic accessibility and equilibrium of major cities in the Yangtze River Delta region, and draws the following conclusions: (1) the improvement of traffic accessibility can drive the economic development of the city (2) the highway accessibility of cities in the Yangtze River Delta is high, which proves that the city roads in the region are well paved and the road travel is convenient; (3) the railroad accessibility of the Yangtze River Delta city cluster is low, so the railway paving needs to be accelerated in the regional city development planning, and thus the shortage of road travel needs to be completed. accessibility is low, so in the regional urban development planning, railroad paving needs to accelerate the pace, and then make up for the shortcomings.

ANALYZING THE CRITERIA AFFECTING TRANSITION TO AIRPLANE BY COMPARING DIFFERENT METHODS

This study, using the multi-vehicle approach, discusses the criteria affecting the transition from alternative transportation modes (car, train, bus) to air transportation between city pairs that neither have a hub status nor non-stop flights between them. If these criteria change, the demand for air transportation will increase. For this purpose, a survey was conducted in the provinces of Kayseri and Bursa, which are among the important trade, industry, and tourism centers in Turkey, in the course of three months between January and March, 2018. Logistic regression, the artificial neural network model, and clustering analyses were applied to the data compiled from questionnaires responded to by 501 individuals in Kayseri and 453 individuals in Bursa. According to the empirical findings, it was concluded that the most significant criteria in the transition to air transportation according to all three methods are the cost of travel/ticket price and non-stop flight. Additionally, it was observed that the Artificial Neural Networks (ANN) model made more accurate predictions compared to others. This study is important since it compares three different methods for the purpose of criteria determination concerning the choice of transportation modes.

The local socio-economic impacts of offshore wind farms

The offshore wind farm (OWF) industry is of growing importance, particularly in Europe. However, the local socio-economic impacts of OWF projects have received little attention compared with biophysical impacts. Yet, they have the potential to be significant for the regeneration of declining coastal communities. Drawing on findings from academic and industry literature, from a review of ESs (Environmental Statements) for OWFs and from particular case studies, it highlights some of the differential coverage of social and economic impacts, and the differences between predicted and actual impacts, by stage in project life. For example, the ES predictions substantially overestimate local offshore construction stage economic impacts, but underestimate other elements of the OWF lifecycle, including onshore construction, and especially the 20–25 years of the operation and management stage. The Aberdeen (Scotland) case study shows the importance of the engagement strategy of the developer. The case study of the major Hornsea projects, off the coast of Yorkshire (England), also highlights the positive and cumulative impacts of scale and hub status, where a programme of large OWFs can have important local impacts. The research identifies some factors leading to the identified outcomes, including the changing size and location of OWF projects, the relevant legislative and regulatory context behind the decision-making processes for OWF projects, and the responses and relationships of stakeholders involved in the process. The key role of monitoring impacts is an underpinning issue and a requirement for the more effective assessment of impacts.

Hong Kong, the Virus and Illiberalism: Between Flattening the Curve and an Authoritarian Slide?

Can the pandemic measures be used to advance particular political means? The question of correlation between illiberal legal changes adopted amongst the wave of legislation focused on battling COVID has arisen in a number of countries around the world; as an increasing number of states finds leaving restrictions behind in 2022, however, Hong Kong is still battling the Omicron wave of the pandemic. Ever since its transition to China in 1997, Hong Kong has retained its place on the world stage as an international business hub and, while getting closer to the Mainland, enjoyed the freedoms provided by its SAR status. At the same time, by the end of the second decade of the twenty-first century the tensions between the pro-democratic inclinations of the large part of the city’s population and pro-Mainland disposition of the SAR’s political elite began to rise, with proposals of various legal acts put forward by the local government often perceived as encroaching freedoms. The street-level ‘standoff’ between the authorities and the people was brought to a halt by the COVID-19 pandemic; and, with protesting rendered virtually impossible, a number of controversial legal changes were introduced by the government taking advantage of the situation, which, together with the anti-pandemic measures have continued to negatively impact the city’s financial hub status. The purpose of this paper is to analyse the correlation between Hong Kong’s fight with the pandemic and the local government’s taking advantage of the situation in order to implement illiberal legislation, and its aftermath.

Twenty years of airport efficiency and productivity studies: A machine learning bibliometric analysis

Airport efficiency and productivity analysis has attracted increasing attention over the last two decades. During this period, the number of such studies has grown significantly, with more than 100 articles related to the topic having been published in peer-reviewed journals in broad areas including transportation, economics, management, operations research and mathematics. Our study complements the previous literature surveys by adopting bibliometric analysis to improve the understanding of airport efficiency and productivity studies. Our analysis identifies publication patterns (e.g., the most relevant authors, institutions and countries; collaborative networks; key journals; and the most cited articles) and popular research topics (e.g., keyword analysis). The annual growth rate of publications is found to be 10.96%, with an increasing trend during 1999–2019. In terms of geographical distribution, almost half of the studies evaluate the performance of the airport sector in Europe, while 21.88% focus on Asian airports. Airport ownership form and size, hub status and economic regulations are popular variables used to explain variation in airport efficiency.

An environmental management system in seaports: evidence from Malaysia

ABSTRACT Seaports face significant environmental challenges in their role as hubs for logistics activities, particularly since ships are significant contributors to energy consumption, global warming and air and marine pollution. The environmental pressures facing ports has led to the emergence of the green port concept. Port Klang is the largest port in Malaysia, characterised not only by significant container throughput, but also by significant congestion issues, emissions and pollution. These characteristics led to the selection of Port Klang, the nation’s major seaport, as a case study for this analysis of the variables most relevant in the effective implementation of the green port concept and subsequent research into how this green seaport concept influences a seaport’s future competitiveness. To achieve these aims, the Analytic Hierarchy Process (AHP) has been employed. The findings of the analysis suggest that environmental quality, the use of energy and resources, waste handling and habitat quality and greenery are the critical influential factors required for establishing green port hub status and that then port competitiveness is most significantly affected by green operations, sustainable equipment, resources management and cost efficiency at seaports.

Vessel Deployment and De-Hubbing in Maritime Networks: A Case Study on Colombo Port and Its Feeder Market

Generally, vessels are deployed as hub-and-spoke networks to achieve high slot utilization and cost efficiency for shipping lines in global maritime container shipping networks. At the Port of Colombo, most transhipment containers originate from and are destined for Indian ports, the export/import container volume of which has been rapidly increasing, and Indian ports have been developed to accommodate vessel enlargement. In such circumstances, the partial or complete abandonment of a hub (Colombo port) in this region is expected, which is known as “de-hubbing.” This study aims to clarify the impact of port developments and an increase in container cargo demand from the source country on maritime network selection from the perspective of shipping lines. We develop a mixed integer linear programming model to describe vessel deployment, including transhipment via the Colombo port and direct shipment in Indian ports. As a result of the analysis, the number of direct services to Indian ports is expected to increase when the cargo demand of Indian ports increases and the port development of Indian ports is conducted. The progress of the de-hubbing phenomenon decreases vessel size at Colombo port because the container demand at Indian ports is mostly satisfied by newly deployed trunk lines to Indian ports. This study suggests that if Colombo port expects to maintain its hub status, it is critical to consider various other incentives to attract and retain mainline carriers in addition to expanding its port infrastructure. Similarly, if India expects to receive direct calls from mainlines, it is important not only to develop their port infrastructure but also to increase their cargo demand.

Cross-Sectional Characterization of Local Brain Network Connectivity Pre and Post Breast Cancer Treatment and Distinct Association With Subjective Cognitive and Psychological Function.

Objective: We aimed to characterize local brain network connectivity in long-term breast cancer survivors compared to newly diagnosed patients.Methods: Functional magnetic resonance imaging (fMRI) and subjective cognitive and psychological function data were obtained from a group of 76 newly diagnosed, pre-treatment female patients with breast cancer (mean age 57 ± 7 years) and a separate group of 80, post-treatment, female breast cancer survivors (mean age 58 ± 8; mean time since treatment 44 ± 43 months). The network-based statistic (NBS) was used to compare connectivity of local brain edges between groups. Hubs were defined as nodes with connectivity indices one standard deviation or more above network mean and were further classified as provincial (higher intra-subnetwork connectivity) or connector (higher inter-subnetwork connectivity) using the participation coefficient. We determined the hub status of nodes encompassing significantly different edges and correlated the centralities of edges with behavioral measures.Results: The post-treatment group demonstrated significantly lower subjective cognitive function (W = 3,856, p = 0.004) but there were no group differences in psychological distress (W = 2,866, p = 0.627). NBS indicated significantly altered connectivity (p < 0.042, corrected) in the post-treatment group compared to the pre-treatment group largely in temporal, frontal-temporal and temporal-parietal areas. The majority of the regions projecting these connections (78%) met criteria for hub status and significantly less of these hubs were connectors in the post-treatment group (z = 1.85, p = 0.031). Subjective cognitive function and psychological distress were correlated with largely non-overlapping edges in the post-treatment group (p < 0.05).Conclusion: Widespread functional network alterations are evident in long-term survivors of breast cancer compared to newly diagnosed patients. We also demonstrated that there are both overlapping and unique brain network signatures for subjective cognitive function vs. psychological distress.

Does the high‐speed rail network improve economic growth?

AbstractThis paper discusses whether high‐speed rail (HSR) construction in China promotes urban economic growth, and it uses social network analysis (SNA) and a panel threshold model. We provide robust evidence that HSR networks have non‐linear effects on the urban economy. Urban location and transportation hub status change as the density of HSR networks increases, and from 2008 to 2017, the national average annual growth rate of the weighted degree centrality (WDC) was 44.93%. We find the WDC and betweenness centrality (BC) have positive influences on urban economic growth. However, HSR network expansion reduces the economic benefits of HSR because the marginal contribution of new HSR lines to economic productivity decreases and there is a crowding out effect caused by excessive agglomeration. HSR networks can promote the economy of Western China to a greater extent and can promote the economy more in small cities than in large and medium‐sized cities. These findings can help the government rationalize its strategy for designing HSR lines in various regions.

Comment on “Geographic Diversification of the Supply Chains of Japanese Firms”

Supply chains have evolved into ever more complex networks of buyers and sellers over time. A key property of these networks is the interconnectedness of firms. This property is a double-edged sword – while firms benefit from participating in such networks, their very interconnectedness to other firms also exposes them to additional risks. These risks include exogenous shocks brought about by natural disasters and pandemics. Todo and Inoue (2021) provide a review of the empirical evidence of how supply chain participation and diversification affect firms when they experience such shocks (directly or indirectly). The lessons drawn from the literature make sense – reducing the degree of supply chain concentration – whether through increasing substitutability and diversification – can improve the robustness and resilience of supply chain firms. An intriguing finding highlighted by Todo and Inoue (2021) is the impact of geographical diversification of supply chains on the robustness and resilience of firms in the short term and medium/long term. That locally concentrated supply chains are superior to more diffused ones in the medium/longer term seems to suggest that agglomeration economies could be an important element. There are hints in the paper, but the relationship between agglomeration economies and supply chain networks is not fully fleshed out. It is an essential point as agglomeration economies are not just a high concentration of local supply chains. This leads to the question of the micro-foundations of supply chain networks. Todo and Inoue (2021) have been pioneers in using agent-based models to simulate the propagation of shocks from natural disasters through supply chain networks in Japan (Inoue & Todo, 2019a, 2019b, 2020). The one-off impacts of these shocks have been studied using models in which firms are embedded in networks (calibrated with real data) and follow fixed rules on production, inventory as well as sale. These are essentially percolation models which are very useful in estimating the immediate damage from natural disasters. Modeling and simulating longer term effects of shocks will require more malleable firm behavior. Otherwise, the impact of natural disasters might be overestimated. An even more ambitious approach will require the modeling of entry, exit, growth (including through merger) of firms within a network framework. Without more dynamic micro-foundations, it will be difficult for the theoretical literature to catch up to the empirical literature on how firms embedded in supply chains adjust after experiencing shocks. Another point worth highlighting is the conceptualization of risks associated with exogenous shocks such as natural disasters and pandemics. Natural disasters are multidimensional – some aspects can be predicted generally (location – earthquake fault lines, general timing – seasonal typhoon) but not others (frequency and intensity). In terms of micro-foundation, how will/should firms optimize their supply chains given the difficulties involved in assessing these risks? Is there firm-level heterogeneity in these matters? If yes, in what sense? Todo and Inoue's (2021) policy recommendations follow directly from their analyses – greater geographical diversification (away from greater Tokyo and China but more toward developed countries) and state support for Japanese firms abroad in terms of subsidizing the fixed cost of relocation and information provision. These recommendations are likely to be debated in terms of the appropriate boundaries between the market and the state. A salient and critical policy decision during this period has been how to strike a balance between human cost and economic cost. The study by Inoue et al. (2020) is a good start but needs to incorporate the spread of Covid-19 that accompanies the lifting of lockdowns. Both have spatial dimensions embedded in networks that can be simulated. Finally, another important type of Covid-19 policy is state support for firms in the form of wage subsidies, low-interest loans or loan repayment deferment. How should such support be targeted? Given that large firms tend to have greater access to financial resources (internal and external) and small firms account for a larger share of total employment, it would seem sensible to channel more aid to smaller firms. However, the heavy-tailed distribution of supply chain network connections may point to a counterintuitive approach that pays more attention to larger firms with hub status.

Drivers for migration of an intermodal network hub from a port to an inland terminal

This paper explores influences on a migration of hub status in an intermodal network from a port to an inland node by following the life cycle of an inland terminal development. The methodology is a longitudinal case study of the Swedish intermodal system over a period of 20 years, based on documentation, interviews and action research. We observe the changing roles of the Port of Gothenburg and the Falköping terminal at different time periods. These changes are then discussed and influences identified for this migration and new centralisation inland. The longitudinal approach allows a life cycle perspective which reveals the importance of initial public infrastructure development and then the operational importance of integration between shipper and intermodal transport and terminal provision in controlling the network. The integration of the inland terminal in regional logistics strategies was also found to be important in attracting port flows to be transported via the inland hub to be containerised.

Logistics Performance and Its Impact to the Transshipments Operations at Port of Colombo

Transportation services have come to be an increasingly essential part of world trade. Freight shipment movement as a part of the maritime enterprise capabilities very particular traits. For this study, the development of transshipment operations is set in the context of Logistics Indexes of impact. Researches about the outcomes on Port transshipments Operations is particularly untouched. Research will subsidize to the understanding of how Sri Lankan’s Logistics Performance Indexes (LPI) influence the transshipments operations at Colombo Port. Using data gathered from Central Bank Reports, Port Annual Reports, World Bank and Questionnaire survey. There are two-analysis part, (1.) Review of the factors consider building of LPI (2.) Relationship among the transshipment operations. This study will contribute to the issues/challenges, achieving hub status barriers, what are the possible solutions to overcome will discuss, and reviewing too. For this using factor analysis, validity, etc. This research contributes to the understanding of transshipments operations in logistics context. This study will use the data from the year 2007 to 2019, because LPIs also published by World Bank every other in two years. This research will answer the research question on which of Sri Lanka’s LPI has an to the logistics related respondents and Identifying the issues/challenges, logistics association with Colombo Port transshipments operations. Moreover, which LPI have the greatest impact, to what operations enhancements in logistics performance effect on transshipments of Port of Colombo, issues/challenges, and logistics related barriers and possible solutions. The research question is answered using hypotheses, using Pearson’s correlation, regarding Sri Lanka’s Customs, Infrastructure, Logistics quality &amp; Competence, Tracking &amp; Tracing, Timelines and International Shipments. The data analyzed using a linear regression model and the analysis will reveal the influence of the LPIs that are explanatory for Colombo Port transshipments operations. Through the analysis it was found that for transshipments operations, all the hypotheses, except the hypotheses related to Customs and Timelines were excluded from analysis, which means that transshipments operations, there is a linear association with the identified LPIs except for Customs and Timelines. Therefore, the main objective of this research is to identify which LPI and affect the operations at transshipment operations handled at Colombo Port. Other objectives include – Identifying issues in enhancing Transshipment’s operations in port of Colombo, Identifying the LPI indexes related related barriers in order to achieve hub status and possible solutions to overcome these problems.

How does transportation hub status promote the urban economic development? — the mediating effect analysis of innovation

A good traffic hub position has important significance for the development of a city, but it also strengthens the polarization effect, diffusion effect and return effect of the regional central cities for other cities. Does the development of urban hub economy strengthen or weaken these effects? Does hub effect also need other conditions to promote urban economic development? From the perspective of technological innovation, this paper analyses the mediating effect of technology absorption and innovation in the process of urban transportation hub promoting economic development. It is found that the people flow effect in the hub effect can better promote the economic development of cities through the mediating role of knowledge absorptive and innovative ability. In the influence of logistics effect on urban economic development, the mediating role of knowledge absorptive and innovative ability is not significant.

Product specification under a threat of entry: Evidence from Airlines’ departure times

I examine how incumbent airlines adjust their departure times in response to the threat of entry by Southwest Airlines. I find that incumbents space their flights more evenly throughout the day when faced with potential entry. This reaction depends strongly on the level of the incumbent’s market share and hub status at the endpoint airports of a market. The evidence suggests that incumbents’ actions are designed to deter, rather than accommodate, entry. I do not find effects on flight frequency, suggesting that incumbents may rely more on the strategic choice of product attributes than on product proliferation to deter entry.