Rational combinations of Betti diagrams of complete intersections

We investigate decompositions of Betti diagrams over a polynomial ring within the framework of Boij-S\"oderberg theory. That is, given a Betti diagram, we determine if it is possible to decompose it into the Betti diagrams of complete intersections. To do so, we determine the extremal rays of the cone generated by the diagrams of complete intersections and provide a rudimentary algorithm for decomposition.Comment: This research was conducted at the Willamette Mathematics Consortium RE

Firms In Markets Under Uncertainty

We analyze a rational-expectations model of price formation in an intermediate-good market under uncertainty. There is a continuum of dyads, each consisting of an upstream party and a downstream party. Both parties can make specific investments at private cost. As in property-rights models, different governance structures induce different investments. As in rational-expectations models, some parties may invest in acquiring (common-value) information, which is then incorporated into the market-clearing price by the parties' trading behaviors. The informativeness of the price mechanism affects the returns to specific investments and hence the optimal governance structure for individual dyads; meanwhile, the governance-structure choices by individual dyads affect the informativeness of the price mechanism. In equilibrium, firms and the market coexist and shape each other. In particular, the informativeness of the price mechanism can induce ex ante homogeneous dyads to choose heterogeneous governance structures.We thank MIT's Program on Innovation in Markets and Organizations for financial support. Powell thanks the NSF for financial support

Connecting Contemporary Trauma Care to Florence Nightingale\u27s Visionary Work

The impact of Florence Nightingale\u27s visionary work continues to influence the delivery of nursing care in the contemporary emergency department (ED). Her foundational work in the Crimean War resulted in data-based recommendations for using the environment to promote healing and wellness among sick and wounded British soldiers. She advocated for attention to environmental details, including ventilation, air, warmth, drainage, cleanliness, natural light, and low noise levels. These important environmental concepts play a significant role in the nursing management of trauma patients in today\u27s ED. This article features an application of Nightingale\u27s environmental concepts to a trauma patient case exemplar and demonstrates the enduring impact of her work for trauma patients who receive care in the ED

Calculation of steady and unsteady pressures at supersonic speeds with CAP-TSD

A finite difference technique is used to solve the transonic small disturbance flow equation making use of shock capturing to treat wave discontinuities. Thus the nonlinear effects of thickness and angle of attack are considered. Such an approach is made feasible by the development of a new code called CAP-TSD (Computational Aeroelasticity Program - Transonic Small Disturbance), and is based on a fully implicit approximate factorization (AF) finite difference method to solve the time dependent transonic small disturbance equation. The application of the CAP-TSD code to the calculation of low to moderate supersonic steady and unsteady flows is presented. In particular, comparisons with exact linear theory solutions are made for steady and unsteady cases to evaluate shock capturing and other features of the current method. In addition, steady solutions obtained from an Euler code are used to evaluate the small disturbance aspects of the code. Steady and unsteady pressure comparisons are made with measurements for an F-15 wing model and for the RAE tailplane model

Rational-Expectations Equilibrium in Intermediate Good Markets

We analyze a rational-expectations model of information acquisition and price formation in an intermediate- good market: prices and net supply are non-negative, there are no noise traders, and the intermediate good has multiple potential uses. Several of our results differ from the classic Grossman-Stiglitz approach. For example, the price mechanism is more informative at high and low prices and potentially uninformative at middle prices. Also, an informed trade by a producer of one final good amounts to a noise trade from the perspective of a producer of another final good, so (a) as the price mechanism becomes more informative for producers of one final good, it becomes less informative for producers of others, who therefore have a stronger incentive to acquire information, so information acquisition has the strategic-complements property between groups, and (b) having more producers (in multiple groups) become informed need not increase the informativeness of the price mechanism.

Effects of D-instantons

Scattering of fundamental states of type IIB supergravity and superstring theory is discussed at low orders in perturbation theory in the background of a D-instanton. The integration over fermionic zero modes in both the low energy supergravity and in the string theory leads to explicit nonperturbative terms in the effective action. These include a single instanton correction to the known tree-level and one-loop $R^4$ interactions. The `spectrum' of multiply-charged D-instantons is deduced by T-duality in nine dimensions from multiply-wound world-lines of marginally-bound D-particles. This, and other clues, lead to a conjectured SL(2,Z) completion of the $R^4$ terms which suggests that they are not renormalized by perturbative corrections in the zero-instanton sector beyond one loop. The string theory unit-charged D-instanton gives rise to point-like effects in fixed-angle scattering, raising unresolved issues concerning distance scales in superstring theory.Comment: 31 pages, 6 figures, Latex, Reference added, corrected coefficients in expansion of generalized Eisenstein series in equation 66 now agree with hep-th/970414

Six-Dimensional Yang Black Holes in Dilaton Gravity

We study the six-dimensional dilaton gravity Yang black holes of hep-th/0607193, which carry (1,-1) charge in SU(2)xSU(2) gauge group. We find what values of the asymptotic parameters (mass and scalar charge) lead to a regular horizon, and show that there are no regular solutions with an extremal horizon.Comment: 10 pages, 8 EPS graph

Monitoring herpetofauna in a managed forest landscape: effects of habitat types and census techniques

We surveyed the herpetofaunal (amphibian and reptile) communities inhabiting five types of habitat on a managed landscape. We conducted monthly surveys during 1997 in four replicate plots of each habitat type using several different methods of collection. Communities of the two wetland habitats (bottomland wetlands and isolated upland wetlands) were clearly dissimilar from the three terrestrial communities (recent clearcut, pine plantation, and mixed pine–hardwood forest). Among the three terrestrial habitats, the total herpetofaunal communities were dissimilar (P\u3c0.10), although neither faunal constituent group alone (amphibians and squamate reptiles) varied significantly with regard to habitat. Three survey techniques used in the terrestrial habitats were not equally effective in that they resulted in the collection of different subsets of the total herpetofauna. The drift fence technique revealed the presence of more species and individuals in every habitat and was the only one to detect species dissimilarity among habitats. Nonetheless, coverboards contributed to measures of abundance and revealed species not detected by other techniques. We suggest that a combination of census techniques be used when surveying and monitoring herpetofaunal communities in order to maximize the detection of species