Invasive species management in two-patch environments: Agricultural damage control in the raccoon (procyon lotor) problem, Hokkaido, Japan

We develop discrete-time models for analyzing the long run equilibrium outcomes on invasive species management in two-patch environments with migration. In particular, the focus is upon a situation where removal operations for invasive species are implemented only in one patch (controlled patch). The new features of the model are that (i) asymmetry in density dependent migration is considered, which may originate from impact of harvesting as well as heterogeneous habitat conditions, and (ii) the effect of density-dependent catchability is well-taken to account for the nature that required effort level to remove one individual may rise as the existing population decreases. The model is applied for agricultural damage control in the raccoon problem that has occurred in Hokkaido, Japan. Numerical illustration demonstrates that the long run equilibrium outcomes highly depend on the degree of asymmetry in migration as well as the sensitivity of catchability in response to a change in the population size of invasive species. Furthermore, we characterize the conditions under which the economically optimal effort levels are qualitatively affected by the above two factors and aiming at local extermination of invasive species in controlled patch is justified.catchability, meta-population, local extermination, removal effort, density dependent migration

Commuting difference operators arising from the elliptic C_2^{(1)}-face model

We study a pair of commuting difference operators arising from the elliptic C_2^{(1)}-face model. The operators, whose coefficients are expressed in terms of the Jacobi's elliptic theta function, act on the space of meromorphic functions on the weight space of the C_2 type simple Lie algebra. We show that the space of functions spanned by the level one characters of the affine Lie algebra sp(4,C) is invariant under the action of the difference operators.Comment: latex2e file, 19 pages, no figures; added reference

Study on surface degradation of LCFA-GGBF geopolymers by partial water absorption and silane impregnation techniques

When the pore solution becomes supersaturated in Portland cement hardened bodies due to evaporation of moisture, temperature change and so on, salts dissolved in the pore solution precipitate and the surface whitening (efflorescence) and surface roughening may occur. Similar phenomena also occur in hardened geopolymer (GP) (Fig.1). Formation process and resultant minerals are different from those of Portland cement and there are a few studies on GP so far on these events. In this paper, efflorescence and surface roughening were studied using low calcium coal fly ash (LCFA) / ground granulated blast furnace-slag (GGBS) type GP. Primarily, these phenomena were studied by partial water immersion technique (Fig.2). Subsequently, surface impregnation technique by a silane was performed and effective results were obtained as follows: (1) Since efflorescence and surface roughening were promoted in the refrigerator rather than in the constant temperature room (20°C, 60%RH), deterioration of the surface layer of GP is more likely to proceed as the temperature and humidity are lower. In addition, repetition of temperature change promotes deterioration of the surface layer. (2) Efflorescence and surface roughening of GP impairs not only aesthetic appearance of the structure but also sometimes lowers proof stress, so certain measures are necessary. (3) Efflorescence and surface roughening of GP can be suppressed by increasing the GGBS substitution rate (Fig.3). (4) Adjustment of the concentration of alkaline solution may suppress efflorescence and surface roughening. (5) The silane-based surface impregnating material for OPC concrete has the effect of reducing the rate of efflorescence and surface roughening of GP. Please click Additional Files below to see the full abstract