The acquisition of tense-aspect morphology and the regular-irregular debate

This paper reviews research on English past-tense acquisition to test the validity of the single mechanism model and the dual mechanism model, focusing on regular-irregular dissociation and semantic bias. Based on the review, it is suggested that in L1 acquisition, both regular and irregular verbs are governed by semantics; that is, early use of past tense forms are restricted to achievement verbs—regular or irregular. In contrast, some L2 acquisition studies show stronger semantic bias for regular past tense forms (e.g., Housen, 2002, Rohde, 1996). It is argued that L1 acquisition of the past-tense morphology can be accounted for more adequately by the single-mechanism model

A generalization of monotone comparative statics: Correction

We have made a correction to "A generalization of monotone comparative statics", which is published in Economics Bulletin Vol. 3, No. 39. We correct the following three aspects of the original paper: the first and the second are the name and the definition of some fundamental notions, respectively. The third is the proof of the main proposition [Proposition 2.1, pp.5].

Evaluating the Present State of Japan as An International Financial Center

Japan has various advantages over many other countries in terms of the capacity to further develop the capital, financial, and foreign exchange markets as a more internationally-competitive financial center. The advantages include the 2nd largest economic size (large market size), ample financial assets (large investor base), presence of many internationally-competitive knowledge-intensive manufacturing firms (large issuer base), good infrastructure, the 2nd largest stock market (large market access), role of the Japanese yen as one of key international currencies, etc. Despite these advantages and a series of reforms implemented since 1997 under the slogan of Japanese version of “Financial Big Bang”, Japan has not been able to foster an internationally-competitive international financial center until today. The gaps with the United States and United Kingdom have expanded further over the past decade. This paper gives a detailed analysis over the present state of Japan’s capital, financial, and foreign exchange markets to highlight where Japanese advantages and challenges lie, as compared with the United Kingdom and the United States. It also provides a clear picture of Japan’s position in Asia (Korea, Singapore, Hong Kong, and mainland China). It also reviews recent Government’s vision and actions.Japan, International Financial Center, Financial Big Bang

A generalization of monotone comparative statics

In this paper, we generalize the lattice theoretical comparative statics by Li Calzi and Veinott, and Milgrom and Shannon. While their theorem is constructed on lattices, particularly on partially ordered sets, we do not require the antisymmetry on a binary relation defined on the set. On the basis of this result, we can deal with the comparative statics of constrained optimization problems, including the cases with nonlinear constraints, in a very intuitive, but considerably general fashion. Specifically, we can extend the Âgvalue order methodsÂh proposed by Antoniadou and Mirman and Ruble in the context of consumer problems with linear constraints. It is also worth noting that our results on the value order can be applicable for any comparative criterion as long as it is a complete preorder on the domain of the objective function.

Higgsino Dark Matter in High-Scale Supersymmetry

We study a supersymmetric (SUSY) Standard Model in which a Higgsino is light enough to be dark matter, while the other SUSY particles are much heavier than the weak scale. We carefully treat the effects of heavy SUSY particles to the Higgsino nature, especially taking into account the renormalization effects due to the large hierarchy between the Higgsino and the SUSY breaking scales. Inelastic scattering of the Higgsino dark matter with a nucleus is studied, and the constraints on the scattering by the direct detection experiments are discussed. This gives an upper limit on the new physics scale. Bounds on the dark matter-nucleon elastic scattering, the electric dipole moments, and direct production of Higgsinos, on the other hand, give a lower limit. We show the current status on the limits and discuss the future prospects.Comment: 28 pages, 12 figures. Version accepted for publication in JHE

Electroweakly-Interacting Dirac Dark Matter

We consider a class of fermionic dark matter candidates that are charged under both the SU(2)$_L$ and U(1)$_Y$ gauge interactions. In this case a certain amount of dark matter-Higgs couplings, which can split the dark matter into a pair of Majorana fermions, should be present to evade the constraints from the dark matter direct detection experiments. These effects may be probed by means of the dark matter-nucleus scattering via the Higgs-boson exchange process, as well as the electric dipole moments induced by the dark matter and its SU(2)$_L$ partner fields. In this article, we evaluate them with an effective field approach. It turns out that the constraints coming from the experiments for the quantities have already restricted the dark matter with hypercharge $Y\geq 3/2$. Future experiments have sensitivities to probe this class of dark matter candidates, and may disfavor the $Y\geq 1$ cases if no signal is observed. In this case, only the $Y=0$ and $1/2$ cases may be the remaining possibilities for the SU(2)$_L$ charged fermionic dark matter candidates.Comment: 5 pages, 3 figure