Framed Wilson Operators, Fermionic Strings, and Gravitational Anomaly in 4d

We study gapped systems with anomalous time-reversal symmetry and global gravitational anomaly in three and four spacetime dimensions. These systems describe topological order on the boundary of bosonic Symmetry Protected Topological (SPT) Phases. Our description of these phases is via the recent cobordism proposal for their classification. In particular, the behavior of these systems is determined by the geometry of Stiefel-Whitney classes. We discuss electric and magnetic operators defined by these classes, and new types of Wilson lines and surfaces that sit on their boundary. The lines describe fermionic particles, while the surfaces describe a sort of fermionic string. We show that QED with a fermionic monopole exhibits the 4d global gravitational anomaly and has a fermionic $\pi$-flux.Comment: 17 pages, 7 figures, comments encouraged; significantly reworked version, designed to reach a wider audience and with new sections on fermionic monopoles in 4d and Stiefel-Whitney operator

Alternation-Trading Proofs, Linear Programming, and Lower Bounds

A fertile area of recent research has demonstrated concrete polynomial time lower bounds for solving natural hard problems on restricted computational models. Among these problems are Satisfiability, Vertex Cover, Hamilton Path, Mod6-SAT, Majority-of-Majority-SAT, and Tautologies, to name a few. The proofs of these lower bounds follow a certain proof-by-contradiction strategy that we call alternation-trading. An important open problem is to determine how powerful such proofs can possibly be. We propose a methodology for studying these proofs that makes them amenable to both formal analysis and automated theorem proving. We prove that the search for better lower bounds can often be turned into a problem of solving a large series of linear programming instances. Implementing a small-scale theorem prover based on this result, we extract new human-readable time lower bounds for several problems. This framework can also be used to prove concrete limitations on the current techniques.Comment: To appear in STACS 2010, 12 page

A User\u27s Guide to Bringing a Private Nuisance Action

The first element of private nuisance is an “interference substantial in nature.” This leads to the question: what is substantial? Whether interference is substantial depends largely on the facts and circumstances of each individual case. The determination of substantiality is generally a question of fact for a jury as opposed to a question of law for the judge to decide. Substantiality, involves a review of the totality of the circumstances based on a balancing of the rights of the Respondent to use his or her property against the rights of the Petitioner to enjoy their property. The balancing basically amounts to a risk-utility analysis weighing the social value of the conduct involved against the harm to the private interest. Therefore, in order to be successful in your private nuisance action you must prove that the social value of the nuisance is outweighed the harm to you

A Seeded Genetic Algorithm for RNA Secondary Structural Prediction with Pseudoknots

This work explores a new approach in using genetic algorithm to predict RNA secondary structures with pseudoknots. Since only a small portion of most RNA structures is comprised of pseudoknots, the majority of structural elements from an optimal pseudoknot-free structure are likely to be part of the true structure. Thus seeding the genetic algorithm with optimal pseudoknot-free structures will more likely lead it to the true structure than a randomly generated population. The genetic algorithm uses the known energy models with an additional augmentation to allow complex pseudoknots. The nearest-neighbor energy model is used in conjunction with Turner’s thermodynamic parameters for pseudoknot-free structures, and the H-type pseudoknot energy estimation for simple pseudoknots. Testing with known pseudoknot sequences from PseudoBase shows that it out performs some of the current popular algorithms

The Problem of Worker Misclassification

Employee misclassification is a significant problem that continues to plague the labor market. Unscrupulous and unknowing employers alike are costing individual workers and society tremendously. Not only are workers missing out on legal protections, but society is losing contributions from employers that should be paid into different employment systems (payroll taxes, unemployment benefits, workers compensation benefits, etc.)