Simplifying collaboration in co-located virtual environments using the active-passive approach

The design and implementation of co-located immersive virtual environments with equal interaction possibilities for all participants is a complex topic. The main problem, on a fundamental technical level, is the difficulty of providing perspective-correct images for each participant. There is consensus that the lack of a correct perspective view will negatively affect interaction fidelity and therefore also collaboration. Several research approaches focus on providing a correct perspective view to all participants to enable co-located work. However, these approaches are usually either based on custom hardware solutions that limit the number of users with a correct perspective view or software solutions striving to eliminate or mitigate restrictions with custom image-generation approaches. In this paper we investigate an often overlooked approach to enable collaboration for multiple users in an immersive virtual environment designed for a single user. The approach provides one (active) user with a perspective-correct view while other (passive) users receive visual cues that are not perspective-correct. We used this active-passive approach to investigate the limitations posed by assigning the viewpoint to only one user. The findings of our study, though inconclusive, revealed two curiosities. First, our results suggest that the location of target geometry is an important factor to consider for designing interaction, expanding on prior work that has studied only the relation between user positions. Secondly, there seems to be only a low cost involved in accepting the limitation of providing perspective-correct images to a single user, when comparing with a baseline, during a coordinated work approach. These findings advance our understanding of collaboration in co-located virtual environments and suggest an approach to simplify co-located collaboration

Spontaneous mass generation and the small dimensions of the Standard Model gauge groups U(1), SU(2) and SU(3)

The gauge symmetry of the Standard Model is SU(3)_c x SU(2)_L x U(1)_Y for unknown reasons. One aspect that can be addressed is the low dimensionality of all its subgroups. Why not much larger groups like SU(7), or for that matter, SP(38) or E7? We observe that fermions charged under large groups acquire much bigger dynamical masses, all things being equal at a high e.g. GUT scale, than ordinary quarks. Should such multicharged fermions exist, they are too heavy to be observed today and have either decayed early on (if they couple to the rest of the Standard Model) or become reliquial dark matter (if they don't). The result follows from strong antiscreening of the running coupling for those larger groups (with an appropriately small number of flavors) together with scaling properties of the Dyson-Schwinger equation for the fermion mass.Comment: 15 pages, 17 plots. This version incorporates community as well as referee comments. Accepted for publication in Nuclear Physics

2008, A Year of Advances and Accomplishments

Since 1990, the Organization of American States’ national demining assistance programs have been working to educate citizens about landmines and eliminate existing minefields in Nicaragua. The OAS Acción Integral contra las Minas Antipersonal program has successfully worked to coordinate with the Ministry of Education, local representatives, community leaders and volunteers to promote awareness about landmines, protect people from further injuries and provide rehabilitation for survivors

Shannon entropy and particle decays

We deploy Shannon's information entropy to the distribution of branching fractions in a particle decay. This serves to quantify how important a given new reported decay channel is, from the point of view of the information that it adds to the already known ones. Because the entropy is additive, one can subdivide the set of channels and discuss, for example, how much information the discovery of a new decay branching would add; or subdivide the decay distribution down to the level of individual quantum states (which can be quickly counted by the phase space). We illustrate the concept with some examples of experimentally known particle decay distributions.Comment: 12 pages, 18 plots; to appear in Nuclear Physics

Identidad, violencia y migración en américa latina: el caso de las maras

La juventud actual tiende, por la importancia que han adquirido los medios decomunicación y los procesos de transnacionalización de la cultura, a construir modeloshíbridos de identidades. Tratamos entonces de ir más allá de una simple descripción, alretomar aquellos aspectos teóricos que permitan dar cuenta de los elementos queconforman el objeto de investigación y lograr explicar la lógica de los jóvenesmiembros de las maras y la interpretación que éstos hacen de su propia vida, laimportancia de los contextos en la definición de identidades, que en conjunto nospermitan comprender cómo se construyen las maras.Las maras representan hoy un problema que ha rebasado las percepciones de los paísesque conviven con tal fenómeno. Agreguémosle una falta de consenso entre losdiferentes discursos que llevan a una visión con ciertos límites, lo que recae en políticas,programas y en un imaginario colectivo construido en gran medida por fines y políticaspúblicas, sustentadas en el discurso de los medios de comunicación, lo que ha dado pasoa la creación de leyes con matices de persecución, represión y exterminio, y donde se hadejado fuera la perspectiva y el carácter de la responsabilidad social