Finite element analysis of inviscid subsonic boattail flow

A finite element code for analysis of inviscid subsonic flows over arbitrary nonlifting planar or axisymmetric bodies is described. The code solves a novel primitive variable formulation of the coupled irrotationality and compressible continuity equations. Results for flow over a cylinder, a sphere, and a NACA 0012 airfoil verify the code. Computed subcritical flows over an axisymmetric boattailed afterbody compare well with finite difference results and experimental data. Interative coupling with an integral turbulent boundary layer code shows strong viscous effects on the inviscid flow. Improvements in code efficiency and extensions to transonic flows are discussed

Comparison of several methods for predicting separation in a compressible turbulent boundary layer

Several methods for predicting the separation point for a compressible turbulent boundary layer were applied to the flow over a bump on a wind-tunnel wall. Measured pressure distributions were used as input. Two integral boundary-layer methods, three finite-difference boundary-layer methods, and three simple methods were applied at five free-stream Mach numbers ranging from 0.354 to 0.7325. Each of the boundary-layer methods failed to explicitly predict separation. However, by relaxing the theoretical separation criteria, several boundary-layer methods were made to yield reasonable separation predictions, but none of the methods accurately predicted the important boundary-layer parameters at separation. Only one of the simple methods consistently predicted separation with reasonable accuracy in a manner consistent with the theory. The other methods either indicated several possible separation locations or only sometimes predicted separation

Frictional coupling between sliding and spinning motion

We show that the friction force and torque, acting at a dry contact of two objects moving and rotating relative to each other, are inherently coupled. As a simple test system, a sliding and spinning disk on a horizontal flat surface is considered. We calculate, and also measure, how the disk is slowing down, and find that it always stops its sliding and spinning motion at the same moment. We discuss the impact of this coupling between friction force and torque on the physics of granular materials.Comment: 4 pages, 5 figures; submitte

Appreciative Inquiry as Organizational Change in a Community Mental Health Setting

poster abstractAppreciative Inquiry (AI) is an approach to organizational change that focuses on the strengths of an organization – discovering what is working well, and generating ideas within the organization for building on those strengths. AI has been applied in a variety of contexts including education, social work, health care, and academia. Little to no research, however, has applied AI to mental health contexts. The current study reports themes from staff member interviews conducted in the early phases of AI applied in a community mental health center (CMHC); these themes paint a picture of this CMHC “at its best” and will be fed-back to employees to lay the foundation for change and enhancing morale among staff. Interviews were conducted by 11 staff who volunteered from various departments and were trained by research staff at an all-day training. Appreciative Interviews first involved asking staff to describe a time they were at their best at this organization. Next, participants were asked to share what it was about themselves, others, and the setting that contributed to this experience. Additionally, interviewees were asked to “dream into the future” and to describe what they wish to see for this organization. Interviews were audio recorded, transcribed, and de-identified. Iterative, consensus-based coding was conducted by a multidisciplinary team that included CMHC staff. Several consistent themes emerged among participants’ stories. Staff at their best frequently reported feeling effective and seeing success in working with consumers. Other themes included working as a team, communicating well, and trusting one another. Stories also involved feeling valued and supported by their supervisors and coworkers. A foundational aspect involved believing in and caring about consumers with whom they work. Themes from participants’ interviews reflect perceptions of this community mental health center at its best and are consistent with tenets self-determination theory and future study

Efficient Contextualism

This Article recommends an economic methodology of contract interpretation that enables the court to maximize the benefits of exchange for the parties and thereby enhance the institution of contracting. We recommend a methodology that asks the parties to identify the determinants of a surplus maximizing interpretation so that the court can determine whether the determinants raise issues that need to be tried. We thus avoid the false choice between textualist and contextualist methodologies, while allowing the parties and the court to avoid costly litigation. For textualist courts, our methodology helps the judge determine when the terms the parties used are ambiguous enough to require the court to consider context. For contextualist courts, it streamlines the interpretive inquiry by identifying which contextual facts are important and why, which allows courts to avoid or streamline trials. Our method therefore allows courts to avoid the problems of textualism (which can make easy cases difficult) and anything-goes-contextualism (which can make difficult cases unmanageable).Our methodology reflects a model of bargaining that emphasizes the divergent interests and preferences of the parties. Although both parties seek to minimize the costs of contracting, the parties have divergent views about those costs and about the tradeoffs each must make to minimize those costs. Accordingly, we deny that courts can find the meaning of a disputed term in the intent of the parties. Instead, we believe that courts must identify (a) the set of obligations that, in the context of the parties’ private projects and undisputed terms, increase contractual surplus and (b) the party who is in the best position to avoid the dispute (and thus lower the cost of contracting) by identifying the terms on which the parties disagree ex ante.We present a structured analytical framework that courts and other enforcers should use to determine which interpretation offered by the parties maximizes the surplus, given the undisputed terms of the contract and the bargaining position of the parties. Courts and other enforcers should not try to influence how other contractors act, except by faithfully determining the surplus maximizing interpretation; nor should they seek to determine what obligations other contracting parties might have undertaken, nor on how hypothetical bargainers might have bargained

Changes in biomass allocation buffer low CO2 effects on tree growth during the last glaciation

Isotopic measurements on junipers growing in southern California during the last glacial, when the ambient atmospheric [CO2] (ca) was ~180 ppm, show the leaf-internal [CO2] (ci) was approaching the modern CO2 compensation point for C3 plants. Despite this, stem growth rates were similar to today. Using a coupled light-use efficiency and tree growth model, we show that it is possible to maintain a stable ci/ca ratio because both vapor pressure deficit and temperature were decreased under glacial conditions at La Brea, and these have compensating effects on the ci/ca ratio. Reduced photorespiration at lower temperatures would partly mitigate the effect of low ci on gross primary production, but maintenance of present-day radial growth also requires a ~27% reduction in the ratio of fine root mass to leaf area. Such a shift was possible due to reduced drought stress under glacial conditions at La Brea. The necessity for changes in allocation in response to changes in [CO2] is consistent with increased below-ground allocation, and the apparent homoeostasis of radial growth, as ca increases today

Myo/Nog Cells: Targets for Preventing the Accumulation of Skeletal Muscle-Like Cells in the Human Lens

Posterior capsule opacification (PCO) is a vision impairing condition that arises in some patients following cataract surgery. The fibrotic form of PCO is caused by myofibroblasts that may emerge in the lens years after surgery. In the chick embryo lens, myofibroblasts are derived from Myo/Nog cells that are identified by their expression of the skeletal muscle specific transcription factor MyoD, the bone morphogenetic protein inhibitor Noggin, and the epitope recognized by the G8 monoclonal antibody. The goal of this study was to test the hypothesis that depletion of Myo/Nog cells will prevent the accumulation of myofibroblasts in human lens tissue. Myo/Nog cells were present in anterior, equatorial and bow regions of the human lens, cornea and ciliary processes. In anterior lens tissue removed by capsulorhexis, Myo/Nog cells had synthesized myofibroblast and skeletal muscle proteins, including vimentin, MyoD and sarcomeric myosin. Alpha smooth muscle actin (a-SMA) was detected in a subpopulation of Myo/Nog cells. Areas of the capsule denuded of epithelial cells were surrounded by Myo/Nog cells. Some of these cell free areas contained a wrinkle in the capsule. Depletion of Myo/Nog cells eliminated cells expressing skeletal muscle proteins in 5-day cultures but did not affect cells immunoreactive for beaded filament proteins that accumulate in differentiating lens epithelial cells. Transforming growth factor-betas 1 and 2 that mediate an epithelial-mesenchymal transition, did not induce the expression of skeletal muscle proteins in lens cells following Myo/Nog cell depletion. This study demonstrates that Myo/Nog cells in anterior lens tissue removed from cataract patients have undergone a partial differentiation to skeletal muscle. Myo/Nog cells appear to be the source of skeletal muscle-like cells in explants of human lens tissue. Targeting Myo/Nog cells with the G8 antibody during cataract surgery may reduce the incidence of PCO

Human Resources and the Resource Based View of the Firm

The resource-based view (RBV) of the firm has influenced the field of strategic human resource management (SHRM) in a number of ways. This paper explores the impact of the RBV on the theoretical and empirical development of SHRM. It explores how the fields of strategy and SHRM are beginning to converge around a number of issues, and proposes a number of implications of this convergence

Centennial-scale reductions in nitrogen availability in temperate forests of the United States

Forests cover 30% of the terrestrial Earth surface and are a major component of the global carbon (C) cycle. Humans have doubled the amount of global reactive nitrogen (N), increasing deposition of N onto forests worldwide. However, other global changes—especially climate change and elevated atmospheric carbon dioxide concentrations—are increasing demand for N, the element limiting primary productivity in temperate forests, which could be reducing N availability. To determine the long-term, integrated effects of global changes on forest N cycling, we measured stable N isotopes in wood, a proxy for N supply relative to demand, on large spatial and temporal scales across the continental U.S.A. Here, we show that forest N availability has generally declined across much of the U.S. since at least 1850 C.E. with cool, wet forests demonstrating the greatest declines. Across sites, recent trajectories of N availability were independent of recent atmospheric N deposition rates, implying a minor role for modern N deposition on the trajectory of N status of North American forests. Our results demonstrate that current trends of global changes are likely to be consistent with forest oligotrophication into theforeseeable future, further constraining forest C fixation and potentially storage