148,038 research outputs found

    An Additive Basis for the Chow Ring of \bar{M}_{0,2}(P^r,2)

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    We begin a study of the intersection theory of the moduli spaces of degree two stable maps from two-pointed rational curves to arbitrary-dimensional projective space. First we compute the Betti numbers of these spaces using Serre polynomial and equivariant Serre polynomial methods developed by E. Getzler and R. Pandharipande. Then, via the excision sequence, we compute an additive basis for their Chow rings in terms of Chow rings of nonlinear Grassmannians, which have been described by Pandharipande. The ring structure of one of these Chow rings is addressed in a sequel to this paper.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

    The Status of Supersymmetry

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    Supersymmetry searches are about to enter an important new era. With LEP 200 and the Main Injector, they will, for the first time, begin to probe significant regions of the supersymmetric parameter space. There is a real chance that supersymmetry might indeed be found before the advent of the LHC.Comment: Invited talk given at PbarP95, May 9-13, 1995, Fermilab. This summary is intended for experimentalist

    On Farber's invariants for simple 2q2q-knots

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    Let KK be a simple 2q2q-knot with exterior XX. We show directly how the Farber quintuple (A,Π,α,,ψ)(A,\Pi,\alpha,\ell,\psi) determines the homotopy type of XX if the torsion subgroup of A=πq(X)A=\pi_q(X) has odd order. We comment briefly on the possible role of the EHP sequence in recovering the boundary inclusion from the duality pairings \ell and ψ\psi. Finally we reformulate the Farber quintuple as an hermitian self-duality of an object in an additive category with involution.Comment: v2. Minor reorganization and corrections to final sectio

    Nitrogen retention in the riparian zone of watersheds underlain by discontinuous permafrost

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    Thesis (M.S.) University of Alaska Fairbanks, 2005Riparian zones function as important ecotones for reducing nitrate concentration in groundwater and inputs into streams. In the boreal forest of interior Alaska, permafrost confines subsurface flow through the riparian zone to shallow organic horizons, where plant uptake of nitrate and denitrification are typically high. Two research questions were addressed in this study: 1) how does riparian zone nitrogen retention vary in watersheds underlain by discontinuous permafrost, and 2) what is the contribution of denitrification to riparian zone nitrogen retention? To estimate the contribution of the riparian zone to watershed nitrogen retention, I analyzed groundwater chemistry using an end-member mixing model. To assess the importance of denitrification as a mechanism of nitrogen retention, I conducted field denitrification assays using the acetylene block technique. Over the summer, nitrogen retention averaged 0.75 and 0.22 mmol N m⁻² d⁻¹ in low and high permafrost watersheds, respectively. Compared with the fluvial export of nitrogen, the retention rate of nitrogen in the riparian zone is 10 - 15% of the loss rate in stream flow. Denitrification accounted for a small proportion (3%) of total nitrogen retention in the riparian zone. Variation in nitrogen retention between watersheds did not account for differences in stream nitrate concentration between watersheds.Introduction -- Factors controlling denitrification -- Riparian zones as nutrient filters -- Models of riparian zone function -- Permafrost and hydrology -- Caribou Poker Creeks Research Watershed (CPCRW) -- References -- Nitrogen retention in the riparian zone of watersheds underlain by discontinuous permafrost -- Conclusions -- References

    Cyber Warfare and the Crime of Aggression: The Need for Individual Accountability on Tomorrow’s Battlefield

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    As cyberspace matures, the international system faces a new challenge in confronting the use of force. Non-State actors continue to grow in importance, gaining the skill and the expertise necessary to wage asymmetric warfare using non-traditional weaponry that can create devastating real-world consequences. The international legal system must adapt to this battleground and provide workable mechanisms to hold aggressive actors accountable for their actions. The International Criminal Court--the only criminal tribunal in the world with global reach--holds significant promise in addressing this threat. The Assembly of State Parties should construct the definition of aggression to include these emerging challenges. By structuring the definition to confront the challenges of cyberspace--specifically non-State actors, the disaggregation of warfare, and new conceptions of territoriality--the International Criminal Court can become a viable framework of accountability for the wars of the twenty-first century
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