On the Economics of Ramping Rate Restrictions at Hydro Power Plants: Balancing Profitability and Environmental Costs

This paper examines the impact of ramping rate restrictions imposed on hydro operations to protect aquatic ecosystems. A dynamic optimization model of the profit maximizing decisions of a hydro operator is solved for various restrictions on water flow, using data for a representative hydro operation in Ontario. Profits are negatively affected, but for a range of restrictions the impact is not large. Ramping restrictions cause a redistribution of hydro production over a given day, which can result in an increase in total hydro power produced. This affects the need for power from other sources with consequent environmental impacts.

Contrasting two approaches in real options valuation: contingent claims versus dynamic programming

This paper compares two well-known approaches for valuing a risky investment using real options theory: contingent claims (CC) with risk neutral valuation and dynamic programming (DP) using a constant risk adjusted discount rate. Both approaches have been used in valuing forest assets. A proof is presented which shows that, except under certain restrictive assumptions; DP using a constant discount rate and CC will not yield the same answers for investment value. A few special cases are considered for which CC and DP with a constant discount rate are consistent with each other. An optimal tree harvesting example is presented to illustrate that the values obtained using the two approaches can differ whcn we depart from these special cases to a more realistic scenariio. Further, the implied risk adjusted discount rate calculated from CC is found to vary with the stochastic state variable and stand age. We conclude that for real options problems the CC approach should be used.optimal tree harvesting, real options, contingent claims, dynamic programming

Regime switching in stochastic models of commodity prices: An application to an optimal tree harvesting problem

This paper investigates a regime switching model of stochastic lumber prices in the context of an optimal tree harvesting problem. Using lumber derivatives prices, two lumber price models are calibrated: a regime switching model and a single regime model. In the regime switching model, the lumber price can be in one of two regimes in which different mean reverting price processes prevail. An optimal tree harvesting problem is specified in terms of a linear complementarity problem which is solved using a fully implicit finite difference, fully-coupled, numerical approach. The land value and critical harvesting prices are found to be significantly different depending on which price model is used. The regime switching model shows promise as a parsimonious model of timber prices that can be incorporated into forestry investment problems.optimal tree harvesting, regime switching, calibration, lumber derivatives prices, fully implicit finite difference approach

The Impact of Stochastic Convenience Yield on Long-term Forestry Investment Decisions

This paper investigates whether convenience yield is an important factor in determining optimal decisions for a forestry investment. The Kalman filter method is used to estimate three different models of lumber prices: a mean reverting model, a simple geometric Brownian motion and the two-factor price model due to Schwartz (1997). In the latter model there are two correlated stochastic factors: spot price and convenience yield. The two-factor model is shown to provide a reasonable fit of the term structure of lumber futures prices. The impact of convenience yield on a forestry investment decision is examined using the Schwartz (1997) long-term model which transforms the two-factor price model into a single factor model with a composite price. Using the long-term model an optimal harvesting problem is analyzed, which requires the numerical solution of an impulse control problem formulated as a Hamilton-Jacobi-Bellman Variational Inequality. We compare the results for the long-term model to those from single-factor mean reverting and geometric Brownian motion models. The inclusion of convenience yield through the long-term model is found to have a significant impact on land value and optimal harvesting decisions.

A lost Lancashire Place-Name: Lox(h)am

Der verschwundene Lancashire-Ort Lox(h)am lag vermutlich in der Gemeinde (parish) Penwortham. Der Ortsname Lox(h)am, der als Familienname überlebt hat, ist ein Kompositum, das aus einem Fluss- oder Bachnamen Lox < britisch *Losko- ‘der Verbogene’ und der Dativpluralform hūsum ‘bei den Häusern’, die formal sowohl altenglisch wie altskandinavisch sein kann, gebildet wird. Die Bedeutung wäre dann ‘bei den Häusern, die in Verbindung mit dem Flüsschen Lox stehen’. In diesem Beitrag wird vielmehr eine skandinavische Etymologie für hūsum bevorzugt. Die Anwesenheit von Skandinaviern in diesem Teil von Lancashire in der Wikingerzeit wird durch das Vorhandensein von skandinavischen Personennamen in mittelalterlichen Privaturkunden bestätigt

Light Sheet Microscopy and Image Analysis of Neural Development and Programmed Cell Death in C. Elegans Embryos

The positioning of neuronal cell bodies and neurites is critical for intact functioning of the nervous system. Mapping the positions of the soma and neurites in the brains of developing embryos as important central nervous system structures are being created may yield novel insight into the role of distinct cell groups in creating these structures. New developments in microscopy have made this an excellent time to study neural development in the C. elegans embryo. In the past decade, implementations of highly light efficient methods such as single plane illumination microscopy have rendered it possible to follow development of embryonic structures in 3D with excellent temporal resolution (Huisken et al., 2004) and low phototoxicity. Recent work has resulted in quantitative characterization of the outgrowth of a single neurite in the late, rapidly moving three-fold stage of the C. elegans embryo for the first time (Christensen et al., 2015). In this thesis, I first describe the construction and programming of a single plane illumination microscope (SPIM) based on a design from Hari Shroff\u27s lab (Wu et al., 2011). The microscope is developed especially for use with C. elegans embryos and permits fast image acquisition without excessive photodamage, compared to other forms of microscopy. Second, I describe the use of the SPIM microscope to image the development of a subset of sublateral neurons, the earliest known entrants to the nerve ring (Rapti et al, in preparation), into which they grow in the 1.5-fold stage. I describe an algorithm for automatically aligning developing embryos onto one another until the beginning of the rapid embryonic movements known as twitching, which begin at the start of the twofold stage. I employ my algorithm to align a group of identically imaged embryos onto one another and deduce information about the positioning of the nerve ring in an approximately uniform coordinate system. I determine that nerve rings are precisely positioned in the embryo to within about a micrometer while the cell bodies that grow into the nerve ring are positioned over a much wider distance. My work suggests that the nerve ring grows out towards the ALA neuron as an anchor, and that twitching may begin when the developing nerve ring reaches the ALA. I additionally describe observation of new phenotypes related to the cam-1 mutation, which was previously identified as a regulator of anterior-posterior placement of the nerve ring (Kennerdell et al., 2009). Third, I describe an application of the SPIM microscope for imaging the death of the tail spike cell, a complex, multi-compartment differentiated cell which dies over a period of hours during the three-fold stage, when the animal is rapidly moving in its shell, and cannot be imaged otherwise than with a rapid, light efficient microscope such as the one described here. I determined the time course and confirmed the sequence of events of wild type tail spike cell death. Additionally, I report stronger phenotypes for some known tail spike cell death genes when imaged in the embryo, suggesting that eff-1 plays a stronger role than previously known in clearance of the distal part of the tail spike cell process, and additionally that ced-5 has a strong role in clearance of the same compartment (in addition to its known role in soma clearance). In an appendix I describe work beginning on an extension of the microscope, which will hopefully see the microscope used as a tool for selectively inducing fluorescence in individual cells and following the development of those cells in time. My results demonstrate the utility of single plane illumination microscopy for study of C. elegans embryogenesis and establish fundamental facts about the variability of the C. elegans central nervous system by making direct comparisons between animals. This work contributes to our understanding of the C. elegans nervous system by establishing fundamental bounds on the range of nerve ring positioning between individuals

Community college human resource officers\u27 perceptions of false sexual harassment accusation processing

Sexual harassment in America\u27s academic institutions, including two-year colleges, continues to be an important issue for administrators to address. While people may believe that the potential for false accusations exists, as is true for any inappropriate behavior, little has been written, or presumably, studied about false sexual harassment accusation. A theoretical framework taken from Rotter\u27s Expectancy-Reinforcement Theory (a Social Learning theory) was proposed as a basis to explain the possibility that contemporary conventional behavior may be guiding college administrators who process sexual harassment claims, and those who are participants. It states, in part, that individuals behave in a manner that is goal oriented, and in the context of the expectancy of the goals to be achieved; The Cannon Center for Survey Research at the University of Nevada-Las Vegas facilitated instrument construction, data reception, and data processing. A 15-question survey was constructed, approved, and sent to 870 American community college Human Resource Officers. Additionally, there was a final open response item that collected comments that were analyzed qualitatively. Data were collected and analyzed using, primarily, descriptive and correlational methods; The study\u27s response rate may have been limited by the request to respond to a sensitive topic based on a need to recollect policy and procedure. Yet, the study was still considered to have the potential to provide exploratory information addressing the reality of false sexual harassment accusation identification and processing among community college human resource officers; Generally, the study seemed to suggest that there were, within the two-year college respondents, no rigidly followed conventions regarding the identification and processing of false sexual harassment accusations (FSHA). Specifically, the data show that although an overwhelming majority of the HRO\u27s who responded have participated in sexual harassment complaint processing, only 32% reported policies that specify FSHA penalties available to them, and only 7% reported that their institution had taken action against one who has made a false sexual harassment accusation; Further, the results of the study support the need for changes in two-year college administrative policy and procedure to better insure equitable and fair sexual harassment claim processing for all involved parties. It also suggests that a heightened awareness regarding the potential and extent of false sexual harassment accusations may be appropriate