A timeline algorithm for astronomy missions

An algorithm is presented for generating viewing timelines for orbital astronomy missions of the pointing (nonsurvey/scan) type. The algorithm establishes a target sequence from a list of candidate targets in a way which maximizes total viewing time. Two special cases are treated. One concerns dim targets which, due to lighting constraints, are scheduled only during the antipolar portion of each orbit. They normally require long observation times extending over several revolutions. A minimum slew heuristic is employed to select the sequence of dim targets. The other case deals with bright, or short duration, targets, which have less restrictive lighting constraints and are scheduled during the portion of each orbit when dim targets cannot be viewed. Since this process moves much more rapidly than the dim path, an enumeration algorithm is used to select the sequence that maximizes total viewing time

Non-compact Mirror Bundles and (0,2) Liouville Theories

We study (0,2) deformations of N=2 Liouville field theory and its mirror duality. A gauged linear sigma model construction of the ultraviolet theory connects (0,2) deformations of Liouville field theory and (0,2) deformations of N=2 SL(2,R)/U(1) coset model as a mirror duality. Our duality proposal from the gauged linear sigma model completely agrees with the exact CFT analysis. In the context of heterotic string compactifications, the deformation corresponds to the introduction of a non-trivial gauge bundle. This non-compact Landau-Ginzburg construction yields a novel way to study the gauge bundle moduli for non-compact Calabi-Yau manifolds.Comment: 34 page

Half-Twisted Correlators from the Coulomb Branch

We compute correlators of chiral operators in half-twisted (0,2) supersymmetric gauged linear sigma models. Our results give simple algebraic formulas for a (0,2) generalization of genus zero Gromov-Witten invariants of compact toric varieties. We derive compact expressions for deformed quantum cohomology relations and apply our general method to several examples.Comment: 21 pages, LaTex; typos corrected; some discussion adde

Digital Court Records Access: Social Justice and Judicial Balancing

With its transition from paper to electronic records, the state court system in Maine is entering new, uncharted territory. In drafting rules regarding public access to electronic court records, a critical issue facing the court system is how to go about balancing the privacy interests of the individual and the state’s interest in providing transparency about the court’s operations. Both interests are important in our democracy, and it is critical that we take measures to preserve both. The purpose of writing this essay is to show that Judge Coffin’s judicial philosophy and rights-sensitive balancing process, although the product of a different era, is enduring and, if embraced today by the Maine Supreme Judicial Court, would significantly improve the quality and effectiveness of its decision-making process in determining court rules that appropriately balance the rights of the individual against the interests of the state, thus engendering increased public trust and confidence in its decision. Part One, “Framing the Issue,” sets the stage, identifying the key issue to be decided as well as the significant interests at stake. Part Two, “Why Judge Coffin?,” addresses the question as to why Judge Coffin, if he were alive today, would be concerned about the subject of digital court records access. Part Three, “Judicial Balancing,” provides an overview of Judge Coffin’s rights-sensitive judicial balancing approach to decision-making in the “hard cases” involving human rights and civil liberties. Finally, Part Four, “Bringing Judge Coffin into the Conversation,” imagines embracing Judge Coffin’s judicial philosophy and using his rights-sensitive balancing process as a guide in managing the transition to electronic records. It offers a glimpse into how Judge Coffin, if asked, might go about the task of balancing privacy and transparency in the digital era, with a focus on social justice and access to justice issues

Deformed Quantum Cohomology and (0,2) Mirror Symmetry

We compute instanton corrections to correlators in the genus-zero topological subsector of a (0,2) supersymmetric gauged linear sigma model with target space P1xP1, whose left-moving fermions couple to a deformation of the tangent bundle. We then deduce the theory's chiral ring from these correlators, which reduces in the limit of zero deformation to the (2,2) ring. Finally, we compare our results with the computations carried out by Adams et al.[ABS04] and Katz and Sharpe[KS06]. We find immediate agreement with the latter and an interesting puzzle in completely matching the chiral ring of the former.Comment: AMSLatex, 30 pages, one eps figure. V4: typos corrected, final version appearing in JHE

Three Generations on the Quintic Quotient

A three-generation SU(5) GUT, that is 3x(10+5bar) and a single 5-5bar pair, is constructed by compactification of the E_8 heterotic string. The base manifold is the Z_5 x Z_5-quotient of the quintic, and the vector bundle is the quotient of a positive monad. The group action on the monad and its bundle-valued cohomology is discussed in detail, including topological restrictions on the existence of equivariant structures. This model and a single Z_5 quotient are the complete list of three generation quotients of positive monads on the quintic.Comment: 19 pages, LaTeX. v2: section on anomaly cancellation adde

(0,2) Deformations of Linear Sigma Models

We study (0,2) deformations of a (2,2) supersymmetric gauged linear sigma model for a Calabi-Yau hypersurface in a Fano toric variety. In the non-linear sigma model these correspond to some of the holomorphic deformations of the tangent bundle on the hypersurface. Combinatorial formulas are given for the number of these deformations, and we show that these numbers are exchanged by mirror symmetry in a subclass of the models.Comment: 35 pages; uses xy-fig; typos fixed, acknowledgments adde

Physical aspects of quantum sheaf cohomology for deformations of tangent bundles of toric varieties

In this paper, we will outline computations of quantum sheaf cohomology for deformations of tangent bundles of toric varieties, for those deformations describable as deformations of toric Euler sequences. Quantum sheaf cohomology is a heterotic analogue of quantum cohomology, a quantum deformation of the classical product on sheaf cohomology groups, that computes nonperturbative corrections to analogues of (27*)^3 couplings in heterotic string computations. Previous computations have relied on either physics-based GLSM techniques or computation-intensive brute-force Cech cohomology techniques. This paper describes methods for greatly simplifying mathematical computations, and derives more general results than previously obtainable with GLSM techniques. We will outline recent results (rigorous proofs will appear elsewhere).Comment: LaTeX, 39 pages; v2: references adde

Generic mission planning concepts for space astronomy missions

The past two decades have seen the rapid development of space astronomy, both manned and unmanned, and the concurrent proliferation of the operational concepts and software that have been produced to support each individual project. Having been involved in four of these missions since the '70's and three yet to fly in the present decade, the authors believe it is time to step back and evaluate this body of experience from a macro-systems point of view to determine the potential for generic mission planning concepts that could be applied to future missions. This paper presents an organized evaluation of astronomy mission planning functions, functional flows, iteration cycles, replanning activities, and the requirements that drive individual concepts to specific solutions. The conclusions drawn from this exercise are then used to propose a generic concept that could support multiple missions

Foreword

In their seminal 1890 article, The Right to Privacy, Samuel Warren and Louis Brandeis observed: Recent inventions and business methods call attention to the next step which must be taken for the protection of the person, and for securing to the individual what Judge Cooley calls the right “to be left alone.” Instantaneous photographs and newspaper enterprise have invaded the sacred precincts of private and domestic life; and numerous mechanical devices threaten to make good the prediction that “what is whispered in the closet shall be proclaimed from the housetops.” What is remarkable about this comment is that it could be applied with equal force to today’s world. Although the technologies are different—instant photographs and sensational tabloids have been replaced by Google Glass and tracking technologies—the impulse to “to be let alone” and the fear that “what is whispered in the closet shall be proclaimed from the housetops” remains relevant to today’s privacy concerns. In fact, perhaps the only constant in the modern era has been almost breathless sense of change, a sense that new and unpredictable developments are just around the corner, and that today’s way of dealing with things may not be up to tomorrow’s task. Nowhere is this more evidence than in the area of information and privacy, where technological changes have facilitated an exponential increase in our ability to communicate and to know. According to Eric Schmidt, the former CEO of Google, approximately five exabytes of information were created between the dawn of civilization and the year 2003. Today, the same amount of information is created in less that two days. Most of this data, according to Schmidt, is user generated—Facebook pages, text messages, blogs, etc. As our social relations are increasingly recorded and collected, the risk that information that we think we are “whispering in the closet” is in fact being “proclaimed from the rooftops” have only increased