Beyond Biomass: Valuing Genetic Diversity in Natural Resource Management

Strategies for increasing production of goods from working and natural systems have raised concerns that the diversity of species on which these services depend may be eroding. This loss of natural capital threatens to homogenize global food supplies and compromise the stability of human welfare. We assess the trade off between artificial augmentation of biomass and degradation of biodiversity underlying a populations' ability to adapt to shocks. Our application involves the augmentation of wild stocks of salmon. Practices in this system have generated warnings that genetic erosion may lead to a loss of the “portfolio effect” and the value of this loss is not accounted for in decision making. We construct an integrated bioeconomic model of salmon biomass and genetic diversity. Our results show how practices that homogenize natural systems can still generate positive returns. However, the substitution of more physical capital and labor for natural capital must be maintained for gains to persist, weakens the capacity for adaptation should this investment cease, and can cause substantial loss of population wildness. We apply an emerging optimization method—approximate dynamic programming—to solve the model without simplifying restrictions imposed previously

Effects of Support Structure Geometry on SLM Induced Residual Stresses in Overhanging Features

Selective laser melting (SLM) is a new and rapidly developing manufacturing method for producing full-density, geometrically complex metal parts. The SLM process is time and cost effective for small-scale production; however, wide-spread adoption of this technique is severely limited by residual stresses that can cause large deformations and in-process build failures. The issues associated with residual stress accumulation are most apparent in parts with overhanging features. Due to the complexity of the SLM process, the accumulation of residual stresses is difficult to assess a priori. The deformations and in-process failures caused by residual stress accumulation often lead to an expensive and time consuming iterative manufacturing process. To aid in the development of general SLM design guidelines for overhanging features, the effect of varying two support structure design parameters on residual stress accumulation were investigated. A part-scale thermo-mechanical finite element model was implemented using Diablo, a multi-physics finite element code developed by Lawrence Livermore National Laboratory (LLNL), and trends observed in the model were validated experimentally. By comparing the distribution and magnitude of residual stresses, it was determined that reducing cooling rate gradients in overhanging features reduces the resulting residual stresses. Additionally, it was shown that volume effective material properties can be used to reduce computational costs in computational models of the SLM process

Assistant Principals’ Leadership and Perceptions of Their Roles: A Qualitative Case Study

The purpose of this qualitative case study was to understand assistant principals’ (APs) leadership and perceptions of their roles. The study took place in a suburban school system located in the southeastern United States. The central research question asked, “How do assistant principals lead and perceive their role as APs?” The theory guiding this research was situational leadership theory as it demonstrated how leadership styles must be related to the needs of the constituents. Ambiguity and burnout were examined as factors that can impact APs’ leadership and their perceptions of leadership. The data for this case study were collected through interviews, focus groups, and documents. Data analysis was based upon coding and memoing to ascertain common patterns and themes that emerged during data analysis. The study reflected that a significant gap in AP research exists. The findings indicated that APs are essential leaders within schools. APs’ leadership is based upon the needs of the those whom they lead, and they build relationships to ascertain and support these needs. Additionally, APs benefit from working collaboratively with APs in small groups and with mentors

Experimental trials of wildlife food and cover plants

The bulletin reports on Department of Soil research project No. 206, 'Soil survey'--P. [2].Digitized 2007 AES.Includes bibliographical references (page 24)

An Evolving Definition of Business Income

An Evolving Definition Of Business Incom