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

Geochemical Study of Thermal Waters in the Tutupaca Geothermal Zone, Tacna, South of Peru

In this study, representative samples from hot springs were chemically analyzed. Geothermometers were used to calculate the deep temperatures of geothermal reservoirs on the basis of fluid mineral equilibrium. In all cases, the chemical components are not in equilibrium with the minerals in the reservoir, due to the fact that most of these waters are acidic. Geothermal manifestations in the Tutupaca zone are evidenced by the presence of hot springs, mud pools and fumaroles with temperatures up to 90°C. The pH values range from 2.90 to 6.9 and conductivity from 800 µS/cm to 2900 µS/cm. Geochemical interpretation according to Cl-SO4-HCO3 ternary diagram shows that thermal waters are classified as sulphate, sulphate-chloride and bicarbonate waters. In B-Cl binary diagram the waters of the Tutupaca area are reacting at deep levels with marine sedimentary rocks, which probably have high porosity and permeability and with abundant fractures. The Na-K-Mg triangular diagram was also used to evaluate equilibrium between water and reservoir rocks, showing a linear trend and pointing to an equilibrium temperature of 200°C (Na/K) in the reservoir and fluid dilution or mixing. The d2H and d18O isotopes diagram also show that the thermal waters originate mainly from meteoric water. According to the geological and geochemical exploration results a conceptual hydro-geochemical model has been proposed for the Tutupaca zone. This model shows a geothermal system associated with magmatic sources from where the geothermal fluids emerge. There is a structural trend which allows the deep circulation of the waters between 2 and 3 km. The chemistry of these thermal waters could be explained by the interaction between the thermal fluid with sedimentary and volcanic rocks

Preliminary Experiment on the Plasma Confinement in the Heliotron Field with Buried Ring Conductors

In order to restore the plasma stability in the Heliotron C magnetic field, the Heliotron-P field, which has buried ring conductors inside the vacuum vessel and thus avoids the cusp losses, has been proposed. As a preliminary experiment on the plasma confinement in this field, the plasma behaviour in a mirror field having a current carrying ring conductor, which corresponds to the one section of the Heliotron-P field, is investigated. The plasma injected from a gun into this field rapidly fills up the region near the separatrix showing the existence of the magnetic well. The plasma ( Tₑ≃20 eV, Tₑ≤11 eV, n?10¹1) is stably confined in this field. The predominant loss is the mirror end loss, and the net radial loss time is inferred to be 1.4 msec. Drift instability is observed only in the region of the steep density gradient at the plasma periphery

Geochemical characterization of thermal waters in the Calientes Geothermal Field, Tacna, South of Peru

The Calientes Geothermal Field is located in the Western Cordillera of the Andes in southern of Peru, in the Tacna Region at an altitude of 4400 m.a.s.l. inside of volcanic systems with presence of several tectonic structures. In Calientes we can distinguish two volcanic chains aligned of N-S, on the extreme west of the valley there is volcanic complex Yucamane-Calientes-Yucamane Chico, whereas to the extreme east there are volcanic centers aligned to NESW that have presented activity possibly does more than 4 Ma. The mean lithology is andesitic lava interlayered with some porphyritic lavas and sequences of pyroclastic flows. The Calientes Field is characterized for present a several quantity of geothermal manifestations as hot springs. In October 2007, we realized the study of thermal waters with geochemical methods for interpretation their chemical and isotopic characteristics. The thermal waters in Calientes have discharge temperatures in the range of 50°C to 87°C, near neutral pH of 6.90 to 8.34 and conductivity between 1160 to 5920 µS/cm. The geochemical interpretation of the results by means of the use of Langelier and Pipper diagrams shows that thermal waters are classified into the alkali-chloride waters field, rich in Na and Cl ions. The Cl-SO4-HCO3 triangular diagram shows that most of the geothermal waters are close to the chloride corner, typical of geothermal deep fluids. In binary diagram B-Cl we have noticed that waters of Calientes Field presents high concentration of B (Boron) and high relation in the proportion B/Cl, which might indicate that to deep levels the reaction of the water is producing with the sedimentary marine rocks. The d18O vs dD diagram shows that thermal waters are product of mixing meteoric waters with magmatic fluids. The chemical geothermometry in liquid phase allowed us to estimate the temperature to depth of the geothermal resource in Calientes Field. According the results, the temperatures values estimated have a range from 240 ºC to 280°C

MITOL assists Parkin in mitochondrial localization

PINK1 (PARK6) and PARKIN (PARK2) are causal genes of recessive familial Parkinson's disease. Parkin is a ubiquitin ligase E3 that conjugates ubiquitin to impaired mitochondrial proteins for organelle degradation. PINK1, a Ser/Thr kinase that accumulates only on impaired mitochondria, phosphorylates two authentic substrates, the ubiquitin-like domain of Parkin and ubiquitin. Our group and others have revealed that both the subcellular localization and ligase activity of Parkin are regulated through interactions with phosphorylated ubiquitin. Once PINK1 localizes on impaired mitochondria, PINK1-catalyzed phosphoubiquitin recruits and activates Parkin. Parkin then supplies a ubiquitin chain to PINK1 for phosphorylation. The amplified ubiquitin functions as a signal for the sequestration and degradation of the damaged mitochondria. Although a bewildering variety of Parkin substrates have been reported, the basis for Parkin substrate specificity remains poorly understood. Moreover, the mechanism underlying initial activation and translocation of Parkin onto mitochondria remains unclear, because the presence of ubiquitin on impaired mitochondria is thought to be a prerequisite for the initial PINK1 phosphorylation process. Here, we show that artificial mitochondria-targeted proteins are ubiquitylated by Parkin, suggesting that substrate specificity of Parkin is not determined by its amino acid sequence. Moreover, recruitment and activation of Parkin are delayed following depletion of the mitochondrial E3, MITOL/March5. We propose a model in which the initial step in Parkin recruitment and activation requires protein ubiquitylation by MITOL/March5 with subsequent PINK1-mediated phosphorylation. Because PINK1 and Parkin amplify the ubiquitin signal via a positive feedback loop, the low substrate specificity of Parkin might facilitate this amplification process