Impact of risk aversion and countervailing tax in oligopoly

Kobayashi’s work was partially supported by JSPS KAKENHI Grant Number JP15K03462.The literature recognizes the qualitative effects of risk aversion on oligopolistic market performance, but less is known about their magnitudes. We quantitatively evaluate these effects in Cournot and Bertrand oligopolies where firms maximize mean-variance utilities under linear demand and costs. The impacts are very similar for the two types of oligopoly, but have opposite signs. The impacts of a firm’s risk aversion on outputs, prices, consumer surplus and social welfare can be expressed via potentially observable variables. Since these impacts resemble the effects of firms’ cost changes, a regulator can reduce or eliminate undesirable effects of risk aversion by changing firms’ costs with appropriate countervailing taxes.Publisher PDFPeer reviewe

Monopoly profit lower than oligopoly due to risk aversion

The industry profit is usually maximized under monopoly and falls with the number of firms in a Cournot oligopoly. However, demand uncertainty and risk aversion reduce firms' outputs, thus raising oligopoly profits and reducing monopoly one. Given a liner demand and costs and a mean-variance utility, we obtain the necessary and sufficient condition for a monopoly's profit and utility to be lower than an oligopoly. We also find such a condition for collusion to yield a lower profit. Finally, we provide a sufficient condition for a monopoly profit to be lower than an oligopoly given a general non-linear demand function.Peer reviewe

Equal tax and equal compensation : a fair and efficient way to save climate

We show that “equal tax and equal compensation” (T&C) is fair as justified by the two fairness principles. It differs from any Pigouvian tax with fixed lump-sum payments and can motivate every country to maximize world welfare. It benefits countries with current per capita emissions lower than the world average and would benefit every country when compared with a fair benchmark where emissions are duly penalized and compensated. Subsidizing emission reduction by poll tax is Pareto efficient and Pareto improving over status quo, but unfair. An imperfect T&C with a sub-optimal tax or pyramid taxes can still benefit the world.Peer reviewe

Probiotics for Preventing Cognitive Impairment in Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive and irreversible neurodegenerative disease that results in gradual cognitive impairment and eventually leads to dementia. However, despite AD being one of the most prevalent neurodegenerative diseases in aging societies, no clinically successful therapeutic strategies for its treatment or prevention have been reported to date. Studies have indicated that gut microbial alterations are linked to AD. Probiotics are living microorganisms that are known to confer health benefits to the host when ingested in adequate amounts. Certain strains of probiotics appear to influence the central nervous system (CNS) and behavior via the microbiota-gut-brain axis. Increasing evidence from preclinical and clinical studies has demonstrated that probiotics possess preventive as well as therapeutic potential for AD. It is speculated that probiotics could ameliorate the progression of AD by modulating the inflammatory process, counteracting oxidative stress, and other possible mechanisms, although further studies are needed to understand the details. In this chapter, we will highlight the current understandings of the effects as well as the possible mechanisms of action of probiotics for preventing cognitive impairment in AD

Sw 1644+57/GRB 110328A: the physical origin and the composition of the relativistic outflow

Sw 1644+57/GRB 110328A is a remarkable cosmological X-ray outburst detected by the {\it Swift} satellite. Its early-time ($t\lesssim 0.1$ days since the trigger) X-ray emission resembles some gamma-ray bursts (GRBs), e.g., GRB 090417B. But the late-time flaring X-ray plateau lasting $> 40$ days renders it unique. We examine the possibilities that the outburst is a super-long GRB powered either by the fallback accretion onto a nascent black hole or by a millisecond pulsar, and find out that these two scenarios can address some but not all of the main observational features. We then focus on the model of tidal disruption of a (giant) star by a massive black hole. The mass of the tidal-disrupted star is estimated to be $\gtrsim$ a few solar masses. A simple/straightforward argument for a magnetic origin of the relativistic outflow is presented.Comment: Updated to match the version published in ApJ Letters. 5 pages, 1 figure, 1 tabl

Density Functional Theory of Magnetic Systems Revisited

The Hohenberg-Kohn theorem of density functional theory (DFT) for the case of electrons interacting with an external magnetic field (that couples to spin only) is examined in more detail than previously. A unexpected generalization is obtained: in certain cases (which include half metallic ferromagnets and magnetic insulators) the ground state, and hence the spin density matrix, is invariant for some non-zero range of a shift in uniform magnetic field. In such cases the ground state energy is not a functional of the spin density matrix alone. The energy gap in an insulator or a half metal is shown to be a ground state property of the N-electron system in magnetic DFT.Comment: Four pages, one figure. Submitted for publication, April 13, 2000 Revised, Sept 27, 200