Are All Particles Identical?

We consider the possibility that all particles in the world are fundamentally identical, i.e., belong to the same species. Different masses, charges, spins, flavors, or colors then merely correspond to different quantum states of the same particle, just as spin-up and spin-down do. The implications of this viewpoint can be best appreciated within Bohmian mechanics, a precise formulation of quantum mechanics with particle trajectories. The implementation of this viewpoint in such a theory leads to trajectories different from those of the usual formulation, and thus to a version of Bohmian mechanics that is inequivalent to, though arguably empirically indistinguishable from, the usual one. The mathematical core of this viewpoint is however rather independent of the detailed dynamical scheme Bohmian mechanics provides, and it amounts to the assertion that the configuration space for N particles, even N ``distinguishable particles,'' is the set of all N-point subsets of physical 3-space.Comment: 12 pages LaTeX, no figure

Towards comparative measures of circulation: Insights from Indigenous Australia

Circulation and other forms of temporary movement are of rising importance in the context of overall population mobility. Despite this, analysis is constrained by a lack of appropriate data and techniques for developing summary measures. Ethnographic methods have afforded useful insights into the complex space-time circuits and lifetime sequences involved, but without quantitative indicators these forms of mobility are effectively invisible to researchers and policy makers. Building on prior work in developing countries we advance methodologies for summarising the temporal dimension of circular mobility. Using illustrative data drawn from a variety of field studies among indigenous peoples in Australia we show how lifelines tracing individual mobility profiles can be used to generate systematic measures of frequency and duration. When plotted graphically these reveal distinctive periodicities that correspond to particular forms of mobility behaviour. Because these metrics are scalable and readily amenable to collection in general surveys they offer a unique bridge between the richness of detail that flows from biographic approaches and the aggregate metrics needed for statistical comparison

Semantic web service architecture for simulation model reuse

COTS simulation packages (CSPs) have proved popular in an industrial setting with a number of software vendors. In contrast, options for re-using existing models seem more limited. Re-use of simulation component models by collaborating organizations is restricted by the same semantic issues however that restrict the inter-organization use of web services. The current representations of web components are predominantly syntactic in nature lacking the fundamental semantic underpinning required to support discovery on the emerging semantic web. Semantic models, in the form of ontology, utilized by web service discovery and deployment architecture provide one approach to support simulation model reuse. Semantic interoperation is achieved through the use of simulation component ontology to identify required components at varying levels of granularity (including both abstract and specialized components). Selected simulation components are loaded into a CSP, modified according to the requirements of the new model and executed. The paper presents the development of ontology, connector software and web service discovery architecture in order to understand how such ontology are created, maintained and subsequently used for simulation model reuse. The ontology is extracted from health service simulation - comprising hospitals and the National Blood Service. The ontology engineering framework and discovery architecture provide a novel approach to inter- organization simulation, uncovering domain semantics and adopting a less intrusive interface between participants. Although specific to CSPs the work has wider implications for the simulation community

A Web Services Component Discovery and Deployment Architecture for Simulation Model Reuse

CSPs are widely used in industry, although have yet to operate across organizational boundaries. Reuse across organizations is restricted by the same semantic issues that restrict the inter-organization use of web services. The current representations of web components are predominantly syntactic in nature lacking the fundamental semantic underpinning required to support discovery on the emerging semantic web. Semantic models, in the form of ontology, utilized by web service discovery and deployment architecture provide one approach to support simulation model reuse. Semantic interoperation is achieved through the use of simulation component ontology to identify required components at varying levels of granularity (including both abstract and specialized components). Selected simulation components are loaded into a CSP, modified according to the requirements of the new model and executed. The paper presents the development carried out within CSPI-PDG and Fluidity Group at Brunel University, of an ontology, connector software and web service discovery architecture. The ontology is extracted from simulation scenarios involving airport, restaurant and kitchen service suppliers. The ontology engineering framework and discovery architecture provide a novel approach to inter-organization simulation, adopting a less intrusive interface between participants. Although specific to CSPs the work has wider implications for the simulation community

Information-theoretic temporal Bell inequality and quantum computation

An information-theoretic temporal Bell inequality is formulated to contrast classical and quantum computations. Any classical algorithm satisfies the inequality, while quantum ones can violate it. Therefore, the violation of the inequality is an immediate consequence of the quantumness in the computation. Furthermore, this approach suggests a notion of temporal nonlocality in quantum computation.Comment: v2: 5 pages, refereces added, discussion slightly revised, main result unchanged. v3: typos correcte

Climate change and Pacific Island food systems

Climate change in Pacific Island countries and territories (PICTs) is projected to have significant impacts, including rising sea-levels, more violent tropical cyclones and droughts. Fish stocks in the tropical regions of the Pacific are expected to be directly affected by any changes that may occur in the ocean’s ecosystem. The four alternative scenarios of the future of the Pacific food systems that are reported in this booklet provide important insights into the different dimensions of the food system, including fisheries and forests, trade, affordability and consumption, and public health. The scenarios offer essential information for policy-makers, in order for them to be able to test and take steps toward developing policies that enhance resilience and strengthen adaptation to climate change among fishers and farmers in the Pacific region

Special Theory of Relativity through the Doppler Effect

We present the special theory of relativity taking the Doppler effect as the starting point, and derive several of its main effects, such as time dilation, length contraction, addition of velocities, and the mass-energy relation, and assuming energy and momentum conservation, we discuss how to introduce the 4-momentum in a natural way. We also use the Doppler effect to explain the "twin paradox", and its version on a cylinder. As a by-product we discuss Bell's spaceship paradox, and the Lorentz transformation for arbitrary velocities in one dimension.Comment: 20 pages, 1 figur