"Macroeconomic Market Incentive Plans: History and Theoretical Rationale"

This paper explores the contemporary debate among economists on the means to move the economy toward high employment without inflation-beyond the traditional instruments of monetary and fiscal policy. The authors pay particular attention to the Market Anti-Inflation Plan (MAP), submitted by Lerner and Colander in 1980. The reasons economists have searched for alternative measures relate to the problems associated with wage and price controls. MAP is an anti-inflation plan that allows relative prices to adjust: The scheme increases costs to firms that raise prices, and contains an added incentive to lower prices. Since MAP is designed to fight macroeconomic inflation by changing the incentives of individual price setters, the relationship between microeconomic behavior and macroeconomic outcomes must be addressed. The theoretical justification for MAP is that there is a macroeconomic externality, and MAP can mitigate the ramifications of the externality. However, efforts to more clearly define the nature of this externality require a better understanding of transaction costs. Consequently, there will be the need for a mechanism to integrate such costs into microeconomic and macroeconomic models.

Analysis of Linsker's simulations of Hebbian rules

Linsker has reported the development of center-surround receptive fields and oriented receptive fields in simulations of a Hebb-type equation in a linear network. The dynamics of the learning rule are analyzed in terms of the eigenvectors of the covariance matrix of cell activities. Analytic and computational results for Linsker's covariance matrices, and some general theorems, lead to an explanation of the emergence of center-surround and certain oriented structures. We estimate criteria for the parameter regime in which center-surround structures emerge

The Role of Constraints in Hebbian Learning

Models of unsupervised, correlation-based (Hebbian) synaptic plasticity are typically unstable: either all synapses grow until each reaches the maximum allowed strength, or all synapses decay to zero strength. A common method of avoiding these outcomes is to use a constraint that conserves or limits the total synaptic strength over a cell. We study the dynamic effects of such constraints. Two methods of enforcing a constraint are distinguished, multiplicative and subtractive. For otherwise linear learning rules, multiplicative enforcement of a constraint results in dynamics that converge to the principal eigenvector of the operator determining unconstrained synaptic development. Subtractive enforcement, in contrast, typically leads to a final state in which almost all synaptic strengths reach either the maximum or minimum allowed value. This final state is often dominated by weight configurations other than the principal eigenvector of the unconstrained operator. Multiplicative enforcement yields a “graded” receptive field in which most mutually correlated inputs are represented, whereas subtractive enforcement yields a receptive field that is “sharpened” to a subset of maximally correlated inputs. If two equivalent input populations (e.g., two eyes) innervate a common target, multiplicative enforcement prevents their segregation (ocular dominance segregation) when the two populations are weakly correlated; whereas subtractive enforcement allows segregation under these circumstances. These results may be used to understand constraints both over output cells and over input cells. A variety of rules that can implement constrained dynamics are discussed

An Overview of Climate & Sea-level Changes Over the Past 100 Million Years

Sea-level history reflects the thermal and cryospheric evolution of the Earth, providing a history of ice- sheet behavior and operation of the climate systems under ice-free and glaciated conditions. I compare ice-volume and sea-level estimates obtained from deep Pacific δ18O and Mg/Ca records with those from the mid-Atlantic U.S. obtained by “backstripping”, progressively accounting for the effects of compaction, loading, and thermal subsidence. Peak warmth, sea levels, high CO2 (\u3e1000 ppm), and mostly ice-free condition occurred in the Hothouse Late Cretaceous (ca. 100-66 Ma) and Early Eocene (55-47.9 Ma). During the cool greenhouse (Paleocene, Middle-Late Eocene) sea level was driven by ice growth and decay of small ice sheets. The Earth became a unipolar Icehouse world in the Oligocene-Pliocene (35-2.55 Ma) punctuated by the ice-free Miocene Climate Optimum (~17-15 Ma) and warmth of the Pliocene Climate Optimum, with partial loss of the East Antarctic ice sheet. Very large sea-level changes (60-130 m) were restricted to the past 2.7 Myr northern hemisphere “ice ages”. Following the last glacial sea-level lowering (~130 m), rates of sea-level exceeded 50 mm/yr, slowing to a Common Era “stillstand”, 20th century rise of 1-2 mm/yr, and a modern rise of 3 mm/yr. Projected sea-level rise in the 21st century is ~1 m under high emissions scenarios, with possible upper limit of over 2 m and rates exceeding 10 mm/yr

Complementary transcriptomic, lipidomic, and targeted functional genetic analyses in cultured Drosophila cells highlight the role of glycerophospholipid metabolism in Flock House virus RNA replication

Abstract Background Cellular membranes are crucial host components utilized by positive-strand RNA viruses for replication of their genomes. Published studies have suggested that the synthesis and distribution of membrane lipids are particularly important for the assembly and function of positive-strand RNA virus replication complexes. However, the impact of specific lipid metabolism pathways in this process have not been well defined, nor have potential changes in lipid expression associated with positive-strand RNA virus replication been examined in detail. Results In this study we used parallel and complementary global and targeted approaches to examine the impact of lipid metabolism on the replication of the well-studied model alphanodavirus Flock House virus (FHV). We found that FHV RNA replication in cultured Drosophila S2 cells stimulated the transcriptional upregulation of several lipid metabolism genes, and was also associated with increased phosphatidylcholine accumulation with preferential increases in lipid molecules with longer and unsaturated acyl chains. Furthermore, targeted RNA interference-mediated downregulation of candidate glycerophospholipid metabolism genes revealed a functional role of several genes in virus replication. In particular, we found that downregulation of Cct1 or Cct2, which encode essential enzymes for phosphatidylcholine biosynthesis, suppressed FHV RNA replication. Conclusion These results indicate that glycerophospholipid metabolism, and in particular phosphatidylcholine biosynthesis, plays an important role in FHV RNA replication. Furthermore, they provide a framework in which to further explore the impact of specific steps in lipid metabolism on FHV replication, and potentially identify novel cellular targets for the development of drugs to inhibit positive-strand RNA viruses.http://deepblue.lib.umich.edu/bitstream/2027.42/78268/1/1471-2164-11-183.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/2/1471-2164-11-183-S3.XLShttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/3/1471-2164-11-183-S2.XLShttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/4/1471-2164-11-183.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/5/1471-2164-11-183-S4.XLShttp://deepblue.lib.umich.edu/bitstream/2027.42/78268/6/1471-2164-11-183-S1.XLSPeer Reviewe

A system for advanced facial animation

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 35-36).by Kenneth D. Miller, III.M.Eng