OSGAR: a scene graph with uncertain transformations

An important problem for augmented reality is registration error. No system can be perfectly tracked, calibrated or modeled. As a result, the overlaid graphics are not aligned perfectly with objects in the physical world. This can be distracting, annoying or confusing. In this paper, we propose a method for mitigating the effects of registration errors that enables application developers to build dynamically adaptive AR displays. Our solution is implemented in a programming toolkit called OSGAR. Built upon OpenSceneGraph (OSG), OSGAR statistically characterizes registration errors, monitors those errors and, when a set of criteria are met, dynamically adapts the display to mitigate the effects of the errors. Because the architecture is based on a scene graph, it provides a simple, familiar and intuitive environment for application developers. We describe the components of OSGAR, discuss how several proposed methods for error registration can be implemented, and illustrate its use through a set of examples

Database Analysis to Support Nutrient Criteria Development (Phase II)

The intent of this publication of the Arkansas Water Resources Center is to provide a location whereby a final report on water research to a funding agency can be archived. The Texas Commission on Environmental Quality (TCEQ) contracted with University of Arkansas researchers for a multiple year project titled “Database Analysis to Support Nutrient Criteria Development”. This publication covers the second of three phases of that project and has maintained the original format of the report as submitted to TCEQ. This report can be cited either as an AWRC publication (see below) or directly as the final report to TCEQ

An assessment of the mantle and slab components in the magmas of an oceanic arc volcano: Raoul Volcano, Kermadec arc

Raoul Volcano occupies a simple oceanic subduction setting in the northern part of the Kermadec arc on the Pacific–Australian convergent plate boundary. The primary inputs to the magmatic system that feeds the volcano are a subduction component derived from the subducting old Pacific oceanic lithosphere and its veneer of pelagic sediment, and the overlying peridotitic mantle wedge. Conservative trace elements that are very incompatible during mantle melting are relatively depleted in Raoul lavas indicating a source that has been depleted during an earlier melting event. Major element co-variations indicate magma genesis by 25% near fractional melting of a mantle source that is weakly depleted (2% melt extraction) relative to a fertile MORB source. An important influence on the composition of the mantle component is progressive melt extraction coupled with minimal advection of fresh material into the sub-arc zone followed by melt extraction from a melting column beneath the spreading centre of an adjacent back arc basin. High field strength element and rare earth element systematics indicate involvement of a subduction-related component of constant composition. Two fluid components can be distinguished, one enriched in large ion lithophile elements inferred to be an aqueous fluid that is continuously added to the ascending melt column and the other a less mobile fluid that transfers Th. A homogeneous subduction-related component of constant composition and magnitude arises if the slab-derived flux migrates from the slab–mantle interface to the sub-arc melting column by repeated episodes of amphibole formation and decomposition its composition is then governed by the distribution coefficients of pyroxene and its magnitude by the degree of amphibole saturation of mantle peridotite. The results from Raoul Volcano are comparable to those from other oceanic subduction-related arcs such as South Sandwich and Marianas suggesting that this is a general model for oceanic arcs

Carbon isotope ratioss of coccolith-associated polysaccharides of Emiliania huxleyi as a function of growth rate and CO2 concentration

The calcite plates, or coccoliths, of haptophyte algae including Emiliania huxleyi are formed in intracellular vesicles in association with water–soluble acidic polysaccharides. These coccolith–associated polysaccharides (CAPs) are involved in regulating coccolith formation and have been recovered from sediment samples dating back to ∼180 Ma. Paired measurements of the carbon isotopic compositions of CAPs and coccolith calcite have been proposed as a novel paleo–pCO2 barometer, but additional proxy validation and development are still required. Here we present culture results quantifying carbon isotopic offsets between CAPs and other cellular components: bulk organic biomass, alkenones, and calcite. E. huxleyi was grown in nitrate–limited chemostat experiments at growth rates (µ) of 0.20–0.62/d and carbon dioxide concentrations of 10.7–17.6 µmol/kg. We find that CAPs are isotopically enriched by 4.5–10.1‰ relative to bulk organic carbon, exhibiting smaller isotopic offsets at faster growth rates and lower CO2 concentrations. This variability suggests that CAPs record a complementary signature of past growth conditions with different sensitivity than alkenones or coccolith calcite. By measuring the isotopic compositions of all three molecules and minerals of self-consistent origin, the ratio µ/[CO2(aq)] may be reconstructed with fewer assumptions than current approaches

Quantum-classical transition of the escape rate of uniaxial antiferromagnetic particles in an arbitrarily directed field

Quantum-classical escape rate transition has been studied for uniaxial antiferromagnetic particles with an arbitrarily directed magnetic field. In the case that the transverse and longitudinal fileds coexist, we calculate the phase boundary line between first- and second-order transitions, from which phase diagrams can be obtained. It is shown that the effects of the applied longitudinal magnetic field on quantum-classical transition vary greatly for different relative magnitudes of the non-compensation.Comment: to be appeared in Phys. Rev.

Decoherence of a Superposition of Macroscopic Current States in a SQUID

We show that fundamental conservation laws mandate parameter-free mechanisms of decoherence of quantum oscillations of the superconducting current between opposite directions in a SQUID -- emission of phonons and photons at the oscillation frequency. The corresponding rates are computed and compared with experimental findings. The decohering effects of external mechanical and magnetic noise are investigated

Massale sterfte onder Aziatische korfmosselen in de Maas

In de zomers van 2003 en 2006 kwam in de Maas massale sterfte voor van de Aziatische korfmossel Corbicula fluminea. Op basis van beschikbare gegevens van de waterkwaliteit in de Maas in 2006 lijkt de oorzaak te liggen in een combinatie van ongunstige factoren, zoals een hoge watertemperatuur in combinatie met lage zuurstofgehalten en/of een laag voedselaanbod, die het sterkst lokaal tot uiting komen tijdens een (zomer)periode met lage waterafvoer. Duidelijk werd dat de standaardgegevens van de vaste meetstations onvoldoende informatie leveren om de oorzaak van de lokale mosselsterfte met zekerheid vast te stellen. Hiervoor is het noodzakelijk om zo snel mogelijk na een melding van sterfte op locatie metingen te verrichten. Rijkswaterstaat Limburg heeft hiertoe inmiddels praktische en organisatorische maatregelen genome

Creation and Growth of Components in a Random Hypergraph Process

Denote by an $\ell$-component a connected $b$-uniform hypergraph with $k$ edges and $k(b-1) - \ell$ vertices. We prove that the expected number of creations of $\ell$-component during a random hypergraph process tends to 1 as $\ell$ and $b$ tend to $\infty$ with the total number of vertices $n$ such that $\ell = o(\sqrt[3]{\frac{n}{b}})$. Under the same conditions, we also show that the expected number of vertices that ever belong to an $\ell$-component is approximately $12^{1/3} (b-1)^{1/3} \ell^{1/3} n^{2/3}$. As an immediate consequence, it follows that with high probability the largest $\ell$-component during the process is of size $O((b-1)^{1/3} \ell^{1/3} n^{2/3})$. Our results give insight about the size of giant components inside the phase transition of random hypergraphs.Comment: R\'{e}sum\'{e} \'{e}tend