ADHM Construction of (Anti-)Self-dual Instantons in 4n4n Dimensions

The ADHM construction is a very strong scheme to construct the instantons in four dimensions. We study an ADHM construction of instantons in $4n~(n\geq2)$ dimensions by generalizing this scheme. The higher-dimensional ADHM construction generates the $4n$-dimensional (anti-)self-dual instantons which satisfy the (anti-)self-dual equation in $4n$ dimensions: $F(n)=\pm\ast_{4n}F(n)$. Here $F(n)$ is the $n$th wedge products of the gauge field strength 2-form $F$. We also show that our scheme reproduces the known $4n$-dimensional one-instantons and there are multi-instanton solutions of the 't Hooft type in the dilute instanton gas limit. Moreover we discuss a Harrington-Shepard type caloron in $4n$ dimensions and this monopole limit.Comment: 23 pages, published versio

Final Goods Substitutability and Economic Growth

In this paper, I investigate the effect of substitutability among final goods on welfare growth under the environment that productivity growth in each industry is not independent of one another. In such an environment, less substitutability is favorable to the welfare growth rate and the steady state welfare level, contrasting to Baumol (1967) and Lucas (1988).

Elimination of Competitors: Some Economics of Payment Card Associations

This paper analyzes platforms and rejections in two-sided markets with network externalities, using the specific context of a payment card association. We study the cooperative antitrust determination of the interchange fee by member banks. We use a framework in which banks and merchants may have market power and consumers and merchants decide rationally on whether to buy or accept a payment card developed by Rochet and Tirole (2002). After drawing the welfare implications of a cooperative determination of the interchange fee and antitrust conducts, we describe in detail the factors affecting merchant resistance, compare cooperative and for-profit business models, and make a first cut in the analysis of system competition.

Elimination of Competitors: Some Economics of Payment Card Associations

This paper analyzes platforms and rejections in two-sided markets with network externalities, using the specific context of a payment card association. We study the cooperative antitrust determination of the interchange fee by member banks. We use a framework in which banks and merchants may have market power and consumers and merchants decide rationally on whether to buy or accept a payment card developed by Rochet and Tirole (2002). After drawing the welfare implications of a cooperative determination of the interchange fee and antitrust conducts, we describe in detail the factors affecting merchant resistance, compare cooperative and for-profit business models, and make a first cut in the analysis of system competition.

A new model framework for circumgalactic Lyα\alpha radiative transfer constrained by galaxy-Lyα\alpha forest clustering

We present a new perturbative approach to "constrained Ly$\alpha$ radiative transfer'" (RT) through the circum- and inter-galactic medium (CGM and IGM). We constrain the HI content and kinematics of the CGM and IGM in a physically motivated model, using the galaxy-Ly$\alpha$ forest clustering data from spectroscopic galaxy surveys in QSO fields at $z\sim2-3$. This enables us to quantify the impact of the CGM/IGM on Ly$\alpha$ emission in an observationally constrained, realistic cosmological environment. Our model predicts that the CGM and IGM at these redshifts transmit $\approx80~\%$ of Ly$\alpha$ photons after having escaped from galaxies. This implies that while the inter-stellar medium primarily regulates Ly$\alpha$ escape, the CGM has a non-negligible impact on the observed Ly$\alpha$ line properties and the inferred Ly$\alpha$ escape fraction, even at $z\sim 2-3$. Ly$\alpha$ scattering in the CGM and IGM further introduces an environmental dependence in the (apparent) Ly$\alpha$ escape fraction, and the observed population of Ly$\alpha$ emitting galaxies: the CGM/IGM more strongly suppresses direct Ly$\alpha$ emission from galaxies in overdense regions in the Universe, and redistributes this emission into brighter Ly$\alpha$ haloes. The resulting mean surface brightness profile of the Ly$\alpha$ haloes is generally found to be a power-law $\propto r^{-2.4}$. Although our model still contains arbitrariness, our results demonstrate how (integral field) spectroscopic surveys of galaxies in QSO fields constrain circumgalactic Ly$\alpha$ RT, and we discuss the potential of these models for studying CGM physics and cosmology.Comment: 20 pages, 14 figures, the version accepted in MNRA

Event-Driven Network Model for Space Mission Optimization with High-Thrust and Low-Thrust Spacecraft

Numerous high-thrust and low-thrust space propulsion technologies have been developed in the recent years with the goal of expanding space exploration capabilities; however, designing and optimizing a multi-mission campaign with both high-thrust and low-thrust propulsion options are challenging due to the coupling between logistics mission design and trajectory evaluation. Specifically, this computational burden arises because the deliverable mass fraction (i.e., final-to-initial mass ratio) and time of flight for low-thrust trajectories can can vary with the payload mass; thus, these trajectory metrics cannot be evaluated separately from the campaign-level mission design. To tackle this challenge, this paper develops a novel event-driven space logistics network optimization approach using mixed-integer linear programming for space campaign design. An example case of optimally designing a cislunar propellant supply chain to support multiple lunar surface access missions is used to demonstrate this new space logistics framework. The results are compared with an existing stochastic combinatorial formulation developed for incorporating low-thrust propulsion into space logistics design; our new approach provides superior results in terms of cost as well as utilization of the vehicle fleet. The event-driven space logistics network optimization method developed in this paper can trade off cost, time, and technology in an automated manner to optimally design space mission campaigns.Comment: 38 pages; 11 figures; Journal of Spacecraft and Rockets (Accepted); previous version presented at the AAS/AIAA Astrodynamics Specialist Conference, 201