Real options valuation of US federal renewable energy research, development, demonstration, and deployment
ENERGY POLICY
Authors: Siddiqui, Afzal S.; Marnay, Chris; Wiser, Ryan H.
Abstract
Benefits analysis of US Federal government research, development, demonstration, and deployment (RD3) programmes for renewable energy (RE) technology improvement typically employs a deterministic forecast of the cost and performance of renewable and nonrenewable fuels. The benefits estimate for the programme derives from the difference between two forecasts, with and without the RD3 programme in place. Three deficiencies of this approach are that it ignores: (1) uncertainty in the cost of non-renewable energy (NRE);(2) the possibility of adjustment to the RD3 effort commensurate with the evolving state of the world; and (3) the underlying technical risk associated with RD. In this paper, an intuitive approach to determining the option value of RE RD is developed. This approach seeks to tackle the first two deficiencies noted above by providing an estimate via a compound real option of an RE RD3 programme in a future with uncertain NRE costs. A binomial lattice reveals the economic intuition underlying the decision-making process, while a numerical example illustrates the option components embedded in a simplified representation of current US Federal RE RD3. (c) 2005 Elsevier Ltd. All rights reserved.
Selective Deposition of 4-Repeat Tau in Cerebral Infarcts
JOURNAL OF NEUROPATHOLOGY AND EXPERIMENTAL NEUROLOGY
Authors: Ichihara, Kazuaki; Uchihara, Toshiki; Nakamura, Ayako; Suzuki, Yoshio; Mizutani, Tomohiko
Abstract
The tau deposits found in neurodegenerative diseases are classified based on their isoforms, that is, 3-repeat (3R) tau and 4-repeat (4R) tau. These isoforms are distinguishable using the antibodies RD3 and RD4, respectively, and Gallyas (Gal) and Campbell-Switzer (CS) silver staining methods, respectively. Tau is also deposited in cerebral infarcts. To characterize the tau profile in these lesions, 21 brains from autopsied patients with cerebral infarcts were analyzed using immunohistochemistry with RD3, RD4, and the anti-paired helical filament antibody AT8 and with Gal and CS staining; all of these techniques identity Alzheimer disease-type neurofibrillary tangles. Fluorescence labeling followed by silver staining in mirror-section pairs was also used to compare the staining patterns. Neurons in and around ischemic foci exhibited the 4R-tau epitope until 34 days postinfarction; argyrophilia with Gal staining persisted longer. The 4R-tau/Gal-positive neurons were negative for 3R-tau and AT8 epitopes and lacked fibrillary structures and argyrophilia by CS staining; they are, therefore, distinct from neurons with neurofibrillary tangles. Positivity for 4R tau/Gal and negativity for 3R tau/CS were also seen in astrocytes and microglia around infarcts. Although this staining profile is characteristic of degenerative processes with 4R-tau deposition, lack of AT8 immunoreactivity and of fibrillary structures in neurons, astrocytes, and microglia indicates that selective 4R-tau deposition represents a stage without tau phosphorylation or fibril formation in cerebral infarcts.