Big Cohen-Macaulay Algebras and Seeds

We delve into the properties possessed by algebras, which we have termed seeds, that map to big Cohen-Macaulay algebras. We will show that over a complete local domain of positive characteristic any two big Cohen-Macaulay algebras map to a common big Cohen-Macaulay algebra. We will also strengthen Hochster and Huneke's "weakly functorial" existence result for big Cohen-Macaulay algebras by showing that the seed property is stable under base change between complete local domains of positive characteristic. We also show that every seed over a positive characteristic local ring (R,m) maps to a big Cohen-Macaulay R-algebra that is an absolutely integrally closed, m-adically separated, quasilocal domain.Comment: 31 pages, typos corrected, Journal-ref adde

Dividend and Capital Gains Taxation in a Cross-Section of Firms

I reconsider the effect of capital income taxation on firm size and firm growth by embedding the nucleus theory of firm development of Sinn (1991) into a framework of monopolistic competition with new firm creation. In a turnover of firms, firm destruction is counterbalanced by a permanent creation of new firms. Young firms are set up using an initial capital infusion of new equity and undergo an intermediate stage of internal growth until they finally reach a steady payout stage. The cross-section then contains firms of all ages and development stages. Dividend and capital gains tax have important effects on initial firm size and growth but also on the creation of new firms and thus on diversity in the economy. First, a differential treatment of dividends and capital gains introduces a distortion in the allocation of capital across firms. Second, dividend as well as capital gains tax are anticipated at the start-up stage of firms. While leaving the firm specific capital stock unaffected, the capitalisation is shown to depress firm creation and aggregate capital accumulation.capital income taxation, investment, firm creation, aggregate production.

Axiomatic Closure Operations, Phantom Extensions, and Solidity

In this article, we generalize a previously defined set of axioms for a closure operation that induces balanced big Cohen-Macaulay modules. While the original axioms were only defined in terms of finitely generated modules, these new ones will apply to all modules over a local domain. The new axioms will lead to a notion of phantom extensions for general modules, and we will prove that all modules that are phantom extensions can be modified into balanced big Cohen-Macaulay modules and are also solid modules. As a corollary, if $R$ has characteristic $p>0$ and is $F$-finite, then all solid algebras are phantom extensions. If $R$ also has a big test element (e.g., if $R$ is complete), then solid algebras can be modified into balanced big Cohen-Macaulay modules. (Hochster and Huneke have previously demonstrated that there exist solid algebras that cannot be modified into balanced big Cohen-Macaulay algebras.) We also point out that tight closure over local domains in characteristic $p$ generally satisfies the new axioms and that the existence of a big Cohen-Macaulay module induces a closure operation satisfying the new axioms.Comment: final revision; to appear in J. Algebr

A Growth Oriented Dual Income Tax

This paper proposes a growth-oriented dual-income tax by combining an allowance for corporate equity with a broadly defined flat tax on personal capital income. Revenue losses are compensated by an increase in the value added tax. The paper demonstrates the neutrality properties of the reform with respect to investment, firm financial decisions and organizational choice. Tax rates are chosen to prevent income shifting from labor to capital income. The reform decisively strengthens investment of domestically owned firms as well as home and foreign based multinationals and boosts savings. Simulations with a calibrated growth model for Switzerland indicate that the reform could add between 2 to 3 percent of GDP in the long run, depending on the specific scenario. Given the slow nature of capital accumulation, it also imposes considerable costs in the short run. We also consider a tax smoothing scenario to offset the intergenerationally redistributive effects.tax reform, investment, financial structure, growth

Screening and advising by a venture capitalist with a time constraint

This paper proposes an intertemporal model of venture capital investment with screening and advising where the venture capitalist´s time endowment is the scarce input factor. Screening improves the selection of firms receiving finance, advising allows firms to develop a marketable product, both have a variable intensity. In our setup, optimal linear contracts solves the moral hazard problem. Screening however asks for an entrepreneur wage and does not allow for upfront payments which would cause severe adverse selection. Project characteristics have implications for screening and advising intensity and the distribution of profits. Finally, we develop a formal version of the "venture capital cycle" by extending the basic setup to a simple model of venture capital supply and demand

Threshold effects for two pathogens spreading on a network

Diseases spread through host populations over the networks of contacts between individuals, and a number of results about this process have been derived in recent years by exploiting connections between epidemic processes and bond percolation on networks. Here we investigate the case of two pathogens in a single population, which has been the subject of recent interest among epidemiologists. We demonstrate that two pathogens competing for the same hosts can both spread through a population only for intermediate values of the bond occupation probability that lie above the classic epidemic threshold and below a second higher value, which we call the coexistence threshold, corresponding to a distinct topological phase transition in networked systems.Comment: 5 pages, 2 figure

Reconsidering tax expenditure estimation: challenges and reforms

We examine the measurement of tax expenditures and offer recommendations aimed at improving their value to analysts and policymakers. We use calculations from NBER's TAXSIM to illustrate some of the problems with the current methodology for estimating tax expenditures. Unlike most previous work on the topic, we focus on how features of the current tax system complicate and compromise the value of information provided by the tax expenditure budget. Our recommendations for reform include presenting revenue estimates for major tax expenditures, reporting some negative tax expenditures, grouping expenditures by conceptually-linked categories, and establishing an appendix for tax expenditure estimates of permanent versions of expiring provisions and AMT interaction effects

Higgs- and quark-inspired modifications of the finite-temperature properties of the Polyakov model

(2+1)-dimensional Georgi-Glashow model, else called the Polyakov model, is explored at nonzero temperatures and in the regime when the Higgs boson is not infinitely heavy. The finiteness of the Higgs-boson mass leads to the appearance of the upper bound on the parameter of the weak-coupling approximation, necessary to maintain the stochasticity of the Higgs vacuum. The modification of the finite-temperature behavior of the model emerging due to the introduction of massless quarks is also discussed.Comment: 4 pages, LaTeX2e, no figures, uses espcrc2.sty, submitted to Nucl. Phys. B (Proc. Suppl.

Satellite power system: Concept development and evaluation program. Volume 3: Power transmission and reception. Technical summary and assessment

Efforts in the DOE/NASA concept development and evaluation program are discussed for the solar power satellite power transmission and reception system. A technical summary is provided together with a summary of system assessment activities. System options and system definition drivers are described. Major system assessment activities were in support of the reference system definition, solid state system studies, critical technology supporting investigations, and various system and subsystem tradeoffs. These activities are described together with reference system updates and alternative concepts for each of the subsystem areas. Conclusions reached as a result of the numerous analytical and experimental evaluations are presented. Remaining issues for a possible follow-on program are identified