Comparative studies on the seasonal occurrence, nymphal development and food menu in two giant water bugs,Diplonychus japonicus vuillefroy andDiplonychus major esaki (Hemiptera: Belostomatidae)

Summary We compared the seasonal changes in population density and nymphal development at different water temperatures and under different food conditions between two giant water bugs,Diplonychus japonicus andD. major, in Okayama, Japan. D. japonicus produced 1–2 generations a year, whileD. major was strictly inivoltine. The developmental velocity was higher inD. japonicus than inD. major. The thermal constant ofD. japonicus was less than that ofD. major. These results suggest thatD. japonicus is adapted, to higher water temperature thanD. major. In the field,D. japonicus preyed predominately on Lymnaeidae and Physidae snails, whileD. major preyed on aquatic insects such as dragonfly nymphs.     

You Thought That This Would Be Easy? Seeking an Understanding of Episodic Volunteering

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - This article is intended as the leading article in a Special Issue of Voluntas devoted to episodic volunteering from a...     

Episodic Volunteering in Sport Events: A Seven-Country Analysis

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - Given its ubiquitous nature, sport events are one of the most popular venues for episodic volunteering around the world....     

COLLATERAL CONSTRAINTS AND THE CURRENT ACCOUNT: THEORY AND EVIDENCE

We investigate the impact of domestic financial frictions on the current account dynamics in Asian countries before and after the Asian financial crisis in 1997–1998 by introducing collateral constraints into the intertemporal current account approach. We examine six Asian countries. Before the crisis, collateral constraints significantly impact the current account in Korea, Malaysia, the Philippines, and Thailand, but after the crisis, they do not. Our study shows that the impact of domestic financial frictions on the current account changes before and after a financial crisis. (JEL F32, F41)     

The dynamic transformation of political systems through social contract: a game theoretic approach

 We consider how the political system of the state evolves in the process of economic development. We present a dynamic public goods economy with non-overlapping generations, which confronts the free-rider problem without the state. In each generation, individuals enter under the unanimous rule a social contract of the political system, either monarchy or democracy, and then attempt to establish the state under the contracted political system. If the state is established, it provides public goods by enforcing tax on its members. Our game theoretic analysis shows: (i) the state can be established if and only if social productivity in terms of the capital stock of public goods is lower than a critical level; (ii) individuals choose democracy if social productivity is sufficiently high, while monarchy may be chosen if it is not; (iii) social productivity stochastically converges to the critical level over generations; and (iv) a simulation result shows several transformation patterns of political systems. Received: 21 June 1994/Accepted: 7 November 1995     

Effects of interspecific competition on development and reproduction in two giant water bugs,Diplonychus japonicus vuillefroy andDiplonychus major esaki (Hemiptera: Belostomatidae)

Summary We studied the interpecific competition between 2 species of predatory aquatic bugs,Diplonychus japonicus andD. major by conducting a field experiment. We set up 3 types of experimental plots in the paddy fields whereD. major predominated. The two plots contained single species of eitherD. japonicus orD. major, respectively, and one plot had both species in equal number. We compared the development and the reproductive performance between plots in each species. InD. japonicus, the number of eggs and early instar nymphs were significantly smaller in the plots containing both species than in the monospecific plots. However, the numbers of late instar nymphs and newly emerged adults were not significantly different between plots. The proportions of starved nymphs in both plots were larger than those in theD. japonicus's natural habitats. The final densities of adults in both plots were lower than those in the natural habitats. These results suggest that lower density ofD. japonicus in these paddy fields is due to the lack of available food for nymphs rather than the effects of interspecific competition withD. major. InD. major, significant differences were not found in the number of eggs, each instar nymphs and adults. These results suggest that the effects of interspecific competition did not affect the reproductive performance ofD. major.     

A Non-cooperative Axiomatization of the Core

We treat a class of multi-person bargaining mechanisms based on games in coalitional form. For this class of games we identify properties of non-cooperative solution concepts, which are necessary and sufficient for the equilibrium outcomes to coincide with the core of the underlying coalitional form game. We view this result as a non-cooperative axiomatization of the core. In contrast to most of the literature on multi-person bargaining we avoid a precise specification of the rules of the game. Alternatively, we impose properties of such games, which give rise to a large class of mechanisms, all of which are relevant for our axiomatization.     

Current Implementation of and Opinions and Concerns Regarding Suicide Education for Social Work Undergraduate Students in Japan: A Cross-Sectional Study

This study explored the current implementation status of and opinions and concerns regarding suicide education at schools of social work in Japan. We conducted a survey of faculty members who taught at least one of the social work subjects. About half the respondents had given a lecture of some kind on suicide, and more than 80% agreed that suicide is an important topic to include in social work program curricula. However, more than half indicated they did not have enough knowledge or skills to teach students about suicide, and more than 60% were concerned about adverse psychological effects of suicide education on students. Our findings highlight the importance of providing faculty members with guidelines for teaching students about suicide.     

How I wonder what you are: Children's songs as a source of mental and internal state information

This study investigated (1) whether children's songs could be potential sources of internal state information and (2) cross-cultural/linguistic differences in the availability of such information. We coded for expressions of mental states and other internal states in 255 English songs, likely accessed by children in the United States, and 255 Japanese songs, likely accessed by Japanese children. The majority of the songs in both samples contained at least one internal state expression, with songs containing four to five tokens and two types of internal state expressions on average. Japanese songs had more types of internal state expressions than English songs when comparing the two samples in proportion scores that controlled for the length of songs. However, differences between English and Japanese songs were negligible in the absolute frequency of tokens and types of internal state expressions, with the exception that Japanese songs were richer in ambiguous internal state expressions.