Temporal Aspects of Smart Contracts for Financial Derivatives

Implementing smart contracts to automate the performance of high-value over-the-counter (OTC) financial derivatives is a formidable challenge. Due to the regulatory framework and the scale of financial risk if a contract were to go wrong, the performance of these contracts must be enforceable in law and there is an absolute requirement that the smart contract will be faithful to the intentions of the parties as expressed in the original legal documentation. Formal methods provide an attractive route for validation and assurance, and here we present early results from an investigation of the semantics of industry-standard legal documentation for OTC derivatives. We explain the need for a formal representation that combines temporal, deontic and operational aspects, and focus on the requirements for the temporal aspects as derived from the legal text. The relevance of this work extends beyond OTC derivatives and is applicable to understanding the temporal semantics of a wide range of legal documentation

On the validity of nonlinear Alfvén resonance in space plasmas

Aims. In the approximation of linear dissipative magnetohydrodynamics (MHD), it can be shown that driven MHD waves in magnetic plasmas with high Reynolds number exhibit a near resonant behaviour if the frequency of the wave becomes equal to the local Alfvén (or slow) frequency of a magnetic surface. This behaviour is confined to a thin region, known as the dissipative layer, which embraces the resonant magnetic surface. Although driven MHD waves have small dimensionless amplitude far away from the resonant surface, this near-resonant behaviour in the dissipative layer may cause a breakdown of linear theory. Our aim is to study the nonlinear effects in Alfvén dissipative layer Methods. In the present paper, the method of simplified matched asymptotic expansions developed for nonlinear slow resonant waves is used to describe nonlinear effects inside the Alfvén dissipative layer. Results. The nonlinear corrections to resonant waves in the Alfvén dissipative layer are derived, and it is proved that at the Alfvén resonance (with isotropic/anisotropic dissipation) wave dynamics can be described by the linear theory with great accuracy

Enzymes as Feed Additive to Aid in Responses Against Eimeria Species in Coccidia-Vaccinated Broilers Fed Corn-Soybean Meal Diets with Different Protein Levels

This research aimed to evaluate the effects of adding a combination of exogenous enzymes to starter diets varying in protein content and fed to broilers vaccinated at day of hatch with live oocysts and then challenged with mixed Eimeria spp. Five hundred four 1-d-old male Cobb-500 chickens were distributed in 72 cages. The design consisted of 12 treatments. Three anticoccidial control programs [ionophore (IO), coccidian vaccine (COV), and coccidia-vaccine + enzymes (COV + EC)] were evaluated under 3 CP levels (19, 21, and 23%), and 3 unmedicated-uninfected (UU) negative controls were included for each one of the protein levels. All chickens except those in unmedicated-uninfected negative controls were infected at 17 d of age with a mixed oral inoculum of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Live performance, lesion scores, oocyst counts, and samples for gut microflora profiles were evaluated 7 d postinfection. Ileal digestibility of amino acids (IDAA) was determined 8 d postinfection. Microbial communities (MC) were analyzed by G + C%, microbial numbers were counted by flow cytometry, and IgA concentrations were measured by ELISA. The lowest CP diets had poorer (P ≤ 0.001) BW gain and feed conversion ratio in the preinfection period. Coccidia-vaccinated broilers had lower performance than the ones fed ionophore diets during pre- and postchallenge periods. Intestinal lesion scores were affected (P ≤ 0.05) by anticoccidial control programs, but responses changed according to gut section. Feed additives or vaccination had no effect (P ≥ 0.05) on IDAA, and diets with 23% CP had the lowest (P ≤ 0.001) IDAA. Coccidial infection had no effect on MC numbers in the ileum but reduced MC numbers in ceca and suppressed ileal IgA production. The COV + EC treatment modulated MC during mixed coccidiosis infection but did not significantly improve chicken performance. Results indicated that feed enzymes may be used to modulate the gut microflora of cocci-vaccinated broiler chickens

Effects of Storage Conditions on the Morphology and Titer of Lentiviral Vectors

Lentiviral vectors are commonly used in laboratory experiments to stably integrate transgenes into host genomes. It has long been observed that storage of virus stocks leads to a decrease in viral titer, but the mechanisms driving this decrease have yet to be identified. To that end, lentiviral vector stocks were generated and stored as follows: room temperature for less than one hour, -80ºC for 24 hours, 4ºC for three days and 4ºC for 7 days. These stocks were subsequently evaluated with regard to their transducing ability and their morphology, specifically particle diameter. The vector that was stored at room temperature served as the control with viral morphology similar to other VSV-G pseudotyped viruses. These stocks were able to transduce ~100% of HEK 293T cells. Particles were unstable under the storage conditions tested, as evidenced by the fact that all stocks stored at -80°C and 4°C required concentration with an ultracentrifuge to generate a preparation suitable for visualization with TEM. The vector stored at -80°C for 24 hours exhibited some morphological changes, but only a slight decrease in titer. The morphology of vectors stored at 4°C for 3 and 7 days was not significantly different from the room temperature control, although titer was reduced to 60% and 30-40%, respectively. Thus, the decrease in titer observed in the lentiviral stocks generated and stored during this investigation appears to be the result of viral particle instability rather than morphological changes to individual particles

Bulk Band Gaps in Divalent Hexaborides

Complementary angle-resolved photoemission and bulk-sensitive k-resolved resonant inelastic x-ray scattering of divalent hexaborides reveal a >1 eV X-point gap between the valence and conduction bands, in contradiction to the band overlap assumed in several models of their novel ferromagnetism. This semiconducting gap implies that carriers detected in transport measurements arise from defects, and the measured location of the bulk Fermi level at the bottom of the conduction band implicates boron vacancies as the origin of the excess electrons. The measured band structure and X-point gap in CaB_6 additionally provide a stringent test case for proper inclusion of many-body effects in quasi-particle band calculations.Comment: 4 pages, 3 figures; new RIXS analysis; accepted for publication in PR

A common graphical form

We present the Common Graphical Form, a low level, abstract machine independent structure which provides a basis for implementing graph reduction on distributed processors. A key feature of the structure is its ability to model disparate abstract machines in a uniform manner; this enables us to experiment with different abstract machines without having to recode major parts of the run-time system for each additional machine. Because we are dealing with a uniform data structure it is possible to build a suite of performance measurement tools to examine interprocessor data-flow and to apply these tools to different abstract machines in order to make relative comparisons between them at run-time. As a bonus to our design brief we exploit the unifying characteristics of the Common Graphical Form by using it as an intermediate language at compile-time

Multiobjective robustness for portfolio optimization in volatile environments

Multiobjective methods are ideal for evolving a set of portfolio optimisation solutions that span a range from high-return/high-risk to low-return/low-risk, and an investor can choose her preferred point on the risk-return frontier. However, there are no guarantees that a low-risk solution will remain low-risk . if the environment changes, the relative positions of previously identified solutions may alter. A low-risk solution may become high-risk and vice versa. The robustness of a Multiobjective Genetic Programming (MOGP) algorithm such as SPEA2 is vitally important in the context of the real-world problem of portfolio optimisation. We explore robustness in this context, providing new definitions and a statistical measure to quantify the robustness of solutions. A new robustness measure is incorporated into a MOGP fitness function to bias evolution towards more robust solutions. This new system ("R-SPEA2") is compared against the original SPEA2 and we present our results

Recursion, lambda abstraction and genetic programming

Module creation and reuse are essential for Genetic Programming (GP) to be effective with larger and more complex problems. This paper presents a particular kind of program structure to serve these purposes: modules are represented as λ abstractions and their reuse is achieved through an implicit recursion. A type system is used to preserve this structure. The structure of λ abstraction and implicit recursion also provides structure abstraction in the program. Since the GP paradigm evolves program structure and contents simultaneously, structure abstraction can reduce the search effort for good program structure. Most evolutionary effort is then focused on the search for correct program contents rather than the structure. Experiments on the Even-N-Parity problem show that, with the structure of λ abstractions and implicit recursion, GP is able to find a general solution which works for any value of N very efficiently

Selective crossover in genetic algorithms

This paper proposes a recombination operator, “selective crossover” for use in genetic algorithm