Impacts of Gap Planting on Soil Density and Erosion

By 2016, there were 32.70 million ha of degraded forests in Indonesia. If it is not quickly rehabilitated, there will be land use changes and expansion of industrial forest plantation, which significantly affects its biodiversity and environmental. This research aims to study the impacts of the gap planting technique with red jabon on soil density and erosion. The research used: (1) the gap planting technique of red jabon with a proportion of the total gap area to the total natural forest area of 40%: 60%, planting distance of 4m x 5m, and the number of trees planted of 200 stems/ha, (2) Digital-Humboldt Static Cone Penetrometer to measure soil density, and (3) stick for soil erosion measurement. The results showed that gap planting with red jabon to rehabilitate degraded natural forests increased the soil density, but its value was categorized as a very loose soil class. On the other hand, the soil erosion in gap area was lower than in degraded natural forest area, because the condition of a part of the degraded forest was unvegetated land, and there were the wastes of branches, twigs, and leaves as well as grown grasses on the soil surface that hinder the soil erosion in the gap area. This research concluded, that the impact of the gap planting on soil density can be neglected, and the impact of the gap planting on soil erosion is positive. Further research on social-economic, biodiversity, effective and efficiency aspects of the gap planting technique for forest rehabilitation are needed before its implementation

Martingale Approach to Pricing Perpetual American Options

The method of Esscher transforms is a tool for valuing options on a stock, if the logarithm of the stock price is governed by a stochastic process with stationary and independent increments. The price of a derivative security is calculated as the expectation, with respect to the risk-neutral Esscher measure, of the discounted payoffs. Applying the optional sampling theorem we derive a simple, yet general formula for the price of a perpetual American put option on a stock whose downward movements are skip-free. Similarly, we obtain a formula for the price of a perpetual American call option on a stock whose upward movements are skip-free. Under the classical assumption that the stock price is a geometric Brownian motion, the general perpetual American contingent claim is analysed, and formulas for the perpetual down-and-out call option and Russian option are obtained. The martingale approach avoids the use of differential equations and provides additional insight. We also explain the relationship between Samuelson's high contact condition and the first order condition for optimalit

Maximizing Dividends without Bankruptcy

Consider the classical compound Poisson model of risk theory, in which dividends are paid to the shareholders according to a barrier strategy. Let b* be the level of the barrier that maximizes the expectation of the discounted dividends until ruin. This paper is inspired by Dickson and Waters (2004). They point out that the shareholders should be liable to cover the deficit at ruin. Thus, they consider b0 , the level of the barrier that maximizes the expectation of the difference between the discounted dividends until ruin and the discounted deficit at ruin. In this paper, b* and b0 are compared, when the claim amount distribution is exponential or a combination of exponential

Risk Theory with the Gamma Process

The aggregate claims process is modelled by a process with independent, stationary and nonnegative increments. Such a process is either compound Poisson or else a process with an infinite number of claims in each time interval, for example a gamma process. It is shown how classical risk theory, and in particular ruin theory, can be adapted to this model. A detailed analysis is given for the gamma process, for which tabulated values of the probability of ruin are provide

Controlling Behaviors in Middle School Youth’s Dating Relationships: Reactions and Help-Seeking Behaviors

This exploratory study examined middle school students’ (N = 380) help-seeking behaviors and other reactions to controlling behaviors in their dating relationships. Over three-fourths of the participants perpetrated and were victimized by controlling behaviors in their dating relationships. Youth used emotional/verbal and dominance/isolation forms of controlling behaviors. More youth were victimized by dominance/isolation controlling behaviors than emotional/verbal controlling behaviors. Gender and age differences emerged when evaluating the type of controlling behaviors youth used. The majority of youth were willing to seek help when confronted with various types of controlling behaviors in their dating relationships. Gender and age differences also emerged in youth’s reactions to controlling behaviors. More understanding of youth’s reactions to controlling behaviors in their dating relationships may assist prevention educators in intervening before controlling behaviors in dating relationships turn into actual dating violence

Holographic bulk viscosity: GPR vs EO

Recently Eling and Oz (EO) proposed a formula for the holographic bulk viscosity, in arXiv:1103.1657, derived from the null horizon focusing equation. This formula seems different from that obtained earlier by Gubser, Pufu and Rocha (GPR) in arXiv:0806.0407 calculated from the IR limit of the two-point function of the trace of the stress tensor. The two were shown to agree only for some simple scaling cases. We point out that the two formulae agree in two non-trivial holographic theories describing RG flows. The first is the strongly coupled N=2* gauge theory plasma. The second is the semi-phenomenological model of Improved Holographic QCD.Comment: 21 pages, 2 figure