Neutron Diffusion and Nucleosynthesis in an Inhomogeneous Big Bang Model

This article presents an original code for Big Bang Nucleosynthesis in a baryon inhomogeneous model of the universe. In this code neutron diffusion between high and low baryon density regions is calculated simultaneously with the nuclear reactions and weak decays that compose the nucleosynthesis process. The size of the model determines the time when neutron diffusion becomes significant. This article describes in detail how the time of neutron diffusion relative to the time of nucleosynthesis affects the final abundances of He4, deuterium and Li7. These results will be compared with the most recent observational constraints of He4, deuterium and Li7. This inhomogeneous model has He4 and deuterium constraints in concordance for baryon to photon ratio eta = (4.3 - 12.3) X 10^{-10} Li7 constraints are brought into concordance with the other isotope constraints by including a depletion factor as high as 5.9. These ranges for the baryon to photon ratio and for the depletion factor are larger than the ranges from a Standard Big Bang Nucleosynthesis model.Comment: 7/15, added reference

Culture-based artefacts to inform ICT design: foundations and practice

Cultural aspects frame our perception of the world and direct the many different ways people interact with things in it. For this reason, these aspects should be considered when designing technology with the purpose to positively impact people in a community. In this paper, we revisit the foundations of culture aiming to bring this concept in dialogue with design. To inform design with cultural aspects, we model reality in three levels of formality: informal, formal, and technical, and subscribe to a systemic vision that considers the technical solution as part of a more complex social system in which people live and interact. In this paper, we instantiate this theoretical and methodological view by presenting two case studies of technology design in which culture-based artefacts were employed to inform the design process. We claim that as important as including issues related to culture in the ICT design agenda—from the conception to the development, evaluation, and adoption of a technology—is the need to support the design process with adequate artefacts that help identifying cultural aspects within communities and translating them into sociotechnical requirements. We argue that a culturally informed perspective on design can go beyond an informative analysis, and can be integrated with the theoretical and methodological framework used to support design, throughout the entire design process

Counting interesting elections

We provide an elementary proof of a formula for the number of northeast lattice paths that lie in a certain region of the plane. Equivalently, this formula counts the lattice points inside the Pitman--Stanley polytope of an n-tuple.Comment: 7 pages, 1 figure; published versio

Strategies and Tools to Raise Energy Awareness Collectively

Providing smart meters and technology for feedback on energy consumption have been considered strategic in current energy policies as part of the battle against climate change. However, feedback alone does not always lead to energy savings. Beyond information on their own consumption and generic advices, people usually still need more specific guidance on how to change their behaviour in an effective and sustainable way. This research considers electricity consumption feedback as a learning element for collective knowledge building, and relies mainly on dialogue and collaboration to engage people with energy conservation as a social issue. To this end, a set of artefacts for triggering and mediating discussions on energy consumption within social groups was developed and evaluated with community leaders in the UK. In a series of 3 workshops, participants discussed how this approach and tools could help them in their mission of disseminating the energy conservation message to the community. Our results show that developing knowledge within a social group is an effective approach in raising awareness, and suggest that tangible artefacts can have an important role in engaging people. Also, initiatives aiming at engaging a wide range of the public must consider different degrees of familiarity with technology, as well as the different perceptions people may have relating energy consumption and environmental protection

Zeta-like Multizeta Values for higher genus curves

We prove or conjecture several relations between the multizeta values for positive genus function fields of class number one, focusing on the zeta-like values, namely those whose ratio with the zeta value of the same weight is rational (or conjecturally equivalently algebraic). These are the first known relations between multizetas, which are not with prime field coefficients. We seem to have one universal family. We also find that interestingly the mechanism with which the relations work is quite different from the rational function field case, raising interesting questions about the expected motivic interpretation in higher genus. We provide some data in support of the guesses.Comment: Expository revisions plus appendices containing proofs of more cases of conjecture