Richard Perrin - Academia.edu (original) (raw)

Papers by Richard Perrin

This study inquires into the spatial welfare impacts of a grain ethanol plant established in an a... more This study inquires into the spatial welfare impacts of a grain ethanol plant established in an area with a beef feeding industry. Beef feeders, corn farmers, and the ethanol plant interact with each other simultaneously in a dynamic market situation. To date, there are no studies which simultaneously analyze the welfare impacts of an ethanol enterprise on the three major players affected by the existence of a plant. In this market situation, some interesting phenomena have been noted which raise some intriguing questions. Why do plants sell ethanol byproduct feed at prices below corn price, even though studies show the byproduct to be a more valuable feed? Why does a plant, which could ship a non-perishable all over the world, choose instead to produce a perishable product? The answers to these questions are affected by the density of corn production, the density of beef production and the size of an ethanol plant in an area. This paper will shed some light on how these and other factors influence welfare and answers the questions posed above.

American Journal of Agricultural Economics, 1996

Abstract-Tobin and Houthakker's work on consumer behav-ior under quantity rationing has been... more Abstract-Tobin and Houthakker's work on consumer behav-ior under quantity rationing has been extended by many authors, especially through the use of duality theory. This paper uses duality theory to extend the work on demand theory under rationing to the case of producer ...

This paper addresses the role of non-parametric analysis in adjusting agricultural productivity m... more This paper addresses the role of non-parametric analysis in adjusting agricultural productivity measures for environmental impacts. The modified Tornquist-Theil index computed using shadow prices derived from the programming procedures is compared and contrasted with a nonparametric hyperbolic Malmquist index for the case of Nebraska agriculture. 1

Notes on Numerical Fluid Mechanics and Multidisciplinary Design (NNFM), 2006

ABSTRACT The objective of the present study is to provide advanced statistical turbulence modelli... more ABSTRACT The objective of the present study is to provide advanced statistical turbulence modelling closures for aerodynamic flows around bodies at high Reynolds number. This study has been carried out by means of theoretical analysis based on the IMFT’s experimental data-base (see part 2 of the book). The two-equation modelling has been reconsidered in the context of the URANS/Organised Eddy Simulation, OES approach in respect of modifying the turbulence length scale involved in the eddy-diffusion coefficient. This has been done from second-order moment closures considerations in OES, from DNS and from the experimental sspectra for the turbulence fluctuating energy.

Alzheimer's & dementia : the journal of the Alzheimer's Association, 2015

The Alzheimer's Disease Neuroimaging Initiative Neuropathology Core (ADNI-NPC) facilitates br... more The Alzheimer's Disease Neuroimaging Initiative Neuropathology Core (ADNI-NPC) facilitates brain donation, ensures standardized neuropathologic assessments, and maintains a tissue resource for research. The ADNI-NPC coordinates with performance sites to promote autopsy consent, facilitate tissue collection and autopsy administration, and arrange sample delivery to the NPC, for assessment using National Institute on Aging-Alzheimer's Association neuropathologic diagnostic criteria. The ADNI-NPC has obtained 45 participant specimens, and neuropathologic assessments have been completed in 36 to date. Challenges in obtaining consent at some sites have limited the voluntary autopsy rate to 58%. Among assessed cases, clinical diagnostic accuracy for Alzheimer disease (AD) is 97%; however, 58% of cases show neuropathologic comorbidities. Challenges facing autopsy consent and coordination are largely resource related. The neuropathologic assessments indicate that ADNI's clinical...

Archives of Otolaryngology-head & Neck Surgery, 2008

Neuropathology : official journal of the Japanese Society of Neuropathology, Jan 12, 2015

It has been hypothesized that the relatively rare autosomal dominant Alzheimer disease (ADAD) may... more It has been hypothesized that the relatively rare autosomal dominant Alzheimer disease (ADAD) may be a useful model of the more frequent, sporadic, late-onset AD (LOAD). Individuals with ADAD have a predictable age at onset and the biomarker profile of ADAD participants in the preclinical stage may be used to predict disease progression and clinical onset. However, the extent to which the pathogenesis and neuropathology of ADAD overlaps with that of LOAD is equivocal. To address this uncertainty, two multicenter longitudinal observational studies, the Alzheimer Disease Neuroimaging Initiative (ADNI) and the Dominantly Inherited Alzheimer Network (DIAN), leveraged the expertise and resources of the existing Knight Alzheimer Disease Research Center (ADRC) at Washington University School of Medicine, St. Louis, Missouri, USA, to establish a Neuropathology Core (NPC). The ADNI/DIAN-NPC is systematically examining the brains of all participants who come to autopsy at the 59 ADNI sites in...

The Spine Journal, 2005

BACKGROUND CONTEXT: Lumbar interbody fusion from a posterior approach affords the advantage of ad... more BACKGROUND CONTEXT: Lumbar interbody fusion from a posterior approach affords the advantage of adding interbody fusion to a posterolateral fusion while avoiding the added morbidity of an anterior spinal approach. Transforaminal lumbar interbody fusion (TLIF) provides anterior column support through a single posterolateral approach to the disc space with minimal neural retraction and disruption of only one facet joint. TLIF has been shown to be safe with relatively few complications. While the cross-sectional area of bone required to obtain an adequate arthrodesis remains unclear, case series consistently report high fusion rates for TLIF. However, prior studies have demonstrated difficulty in removing sufficient disc material through a unilateral approach. PURPOSE: The purpose of this study was to quantitatively and qualitatively analyze the cross-sectional area of vertebral end plate prepared for fusion using a unilateral TLIF approach. STUDY DESIGN/SETTING: A human cadaveric in vitro analysis of vertebral end plate preparation in a TLIF model. PATIENT SAMPLE: 10 human cadaver torsos. OUTCOME MEASURES: Mean percentage of end plate cross-sectional area exposed for fusion.

Journal of neuro-oncology, 1998

We present a case of probable tumor seeding along the needle tract following computer tomography-... more We present a case of probable tumor seeding along the needle tract following computer tomography-guided stereotactic biopsy of an anaplastic astrocytoma in a 23 year old male. Six months after the initial biopsy and 3 months following a second stereotactic procedure for cyst aspiration, a second lesion appeared directly along the biopsy trajectory at a distance from the primary tumor. This lesion is presumed to be recurrent tumor and appears to have been spread iatrogenically following the biopsy of the initial tumor and the subsequent cyst aspiration along the same tract.

Neurosurgery Clinics of North America, 2004

Spinal metastasis is the most commonly en-countered tumor of the spine and represents an ominous ... more Spinal metastasis is the most commonly en-countered tumor of the spine and represents an ominous extension of neoplastic disease. Symptomatic spinal metastases produce a characteristic clinical syndrome beginning with local back or neck pain. All too often, the significance of presenting pain is not appreciated and correct diagnosis is delayed until more blatant manifestations of spinal cord or nerve root dysfunction are manifest. Pain is followed by weakness,numbness, and sphincter dysfunction. The natural history is one of relentless progression to complete and irreversible paralysis unless timely treatment is undertaken. Plain radiographs provide a simple and useful screening test. MRI is, however, the imaging method of choice, providing information concern-ing the level, location, and geometry of the spinal tumor as well as details concerning the bony integrity of the spine, particularly adjacent to a culpable tumor, all of which is essential to determine the management options and treatment strategies. Percutaneous image-guided biopsy is a useful test to establish a tissue diagnosis.

This paper examines changes in agricultural productivity in 18 developing countries over the peri... more This paper examines changes in agricultural productivity in 18 developing countries over the period 1961 to 1985. Because input price series are not available, we use the concept of distance function and the nonparametric, quantity-based Malmquist index approach, and contrast the results with our previous Cobb-Douglas production function approach. The objective is to present an analysis of technological change that is less dependent on the parametric specification of the model. In average terms, the Malmquist constant-returns-to-scale approach indicates that half of these countries have experienced productivity declines. The partitioning of productivity into technical change and technical efficiency components indicates that negative technical change has been responsible for these declines, while most countries have experienced improvements in Farrell efficiency. In addition, countries that tax agriculture most heavily had the most negative rates of productivity change.

Recent studies have revealed that less developed countries (LDCs) have been taxing their agricult... more Recent studies have revealed that less developed countries (LDCs) have been taxing their agricultural sectors at rates of 40-50%. This study uses quantity-based general equilibrium measures of deadweight loss to evaluate the cost of these distortions in 18 of these countries. The Allais-Debreu loss measures indicate that from 7-16% of either output or of the agricultural resource base has been wasted due to the associated misallocation of agricultural inputs across these countries.

ABSTRACT Abstract not available

Recent studies have revealed that LDCs have been taxing their agricultural sectors at rates of 40... more Recent studies have revealed that LDCs have been taxing their agricultural sectors at rates of 40 to 50 percent. While it is widely acknowledged that this taxation might have significant allocative effects, this paper examines a cross-country aggregated agricultural production function. The results estimate that the elasticity of productivity with respect to output prices is about 0.1, indicating that the taxation levels have had very significant productivity impacts. Allais-Debreu measures of deadweight loss indicate that from 7 to 16 percent of output or of the agricultural resource base has been wasted due to the associated misallocation of agricultural inputs across these countries.