Accumulation of heavy metals by aquatic bryophytes in streams and rivers in northern England

A Study was made of the ecology of aquatic bryophytes and their accumulation of metals in rivers of northern England. Field surveys and experiments in the field and laboratory examined the effectiveness of bryophytes as monitors of heavy metal pollution. A survey of 105 river sites (10-m reaches) with Rhynchostegium riparioides was carried out, together with a seasonal survey of this species at seven sites, which also included data for two other species. Details of the aquatic bryophytes present, water chemistry and metal concentrations in mosses are given. The ecological ubiquity of Rhynchostegium was described using principal components analysis and discussed in relation to other macrophytes. A biometric study revealed that marked interpopulation differences in gametophytic characters were correlated with water chemistry variables (NH(_4)-N, PO(_4)-P, Cl, Na) indicative of organic pollution. Significant linear regressions were found between accumulation and aqueous concentrations of Zn, Cd, Ba and Pb. A multiple regression of these and other chonical data suggested several factors had significant effects on accumulation. Seasonal effects were largely chemical in nature, rather than a function of the plants themselves. Experiments supported several findings from the surveys. Zinc uptake proceeded more rapidly than loss and was influenced by aqueous Mg, Ca and humic acids, but not PO(_4)-P, NO(_3)-N or Si. Accumulation was greater in tips of Rhynchostegium than Amblystegium riparium or Fontinalis antipyretica. Results indicate that bryophytes are useful as monitors of pollution. Rhynchostegium in particular is recommended for its ecological ubiquity, its presence in a wide range of aqueous metals and greater accumulation. Applications of bryophytes for specific uses are outlined, with recommendations for different situations. A new model, based on slopes of accumulation, is proposed as a predictive tool

Enhancement of Entanglement Percolation in Quantum Networks via Lattice Transformations

We study strategies for establishing long-distance entanglement in quantum networks. Specifically, we consider networks consisting of regular lattices of nodes, in which the nearest neighbors share a pure, but non-maximally entangled pair of qubits. We look for strategies that use local operations and classical communication. We compare the classical entanglement percolation protocol, in which every network connection is converted with a certain probability to a singlet, with protocols in which classical entanglement percolation is preceded by measurements designed to transform the lattice structure in a way that enhances entanglement percolation. We analyze five examples of such comparisons between protocols and point out certain rules and regularities in their performance as a function of degree of entanglement and choice of operations.Comment: 12 pages, 17 figures, revtex4. changes from v3: minor stylistic changes for journal reviewer, minor changes to figures for journal edito

Primary gas thermometry by means of laser-absorption spectroscopy: Determination of the Boltzmann constant

We report on a new optical implementation of primary gas thermometry based on laser absorption spectrometry in the near infrared. The method consists in retrieving the Doppler broadening from highly accurate observations of the line shape of the R(12) $\nu_{1} + 2 \nu_{2}^{\phantom{1}0} + \nu_{3}$ transition in CO$_{2}$ gas at thermodynamic equilibrium. Doppler width measurements as a function of gas temperature, ranging between the triple point of water and the gallium melting point, allowed for a spectroscopic determination of the Boltzmann constant with a relative accuracy of $\sim1.6\times10^{-4}$.Comment: Submitted to Physical Review Letter

Geodesics of Random Riemannian Metrics

We analyze the disordered Riemannian geometry resulting from random perturbations of the Euclidean metric. We focus on geodesics, the paths traced out by a particle traveling in this quenched random environment. By taking the point of the view of the particle, we show that the law of its observed environment is absolutely continuous with respect to the law of the random metric, and we provide an explicit form for its Radon-Nikodym derivative. We use this result to prove a "local Markov property" along an unbounded geodesic, demonstrating that it eventually encounters any type of geometric phenomenon. We also develop in this paper some general results on conditional Gaussian measures. Our Main Theorem states that a geodesic chosen with random initial conditions (chosen independently of the metric) is almost surely not minimizing. To demonstrate this, we show that a minimizing geodesic is guaranteed to eventually pass over a certain "bump surface," which locally has constant positive curvature. By using Jacobi fields, we show that this is sufficient to destabilize the minimizing property.Comment: 55 pages. Supplementary material at arXiv:1206.494

UTS WIL Quality Framework

Work Integrated Learning (WIL) is a key component of the UTS Strategy and strengthens the idea of the civic university evidenced in UTS 2027 with strategic external partnerships, excellence in Indigenous higher education and commitment to social justice as well as personalised learning, lifetime of learning, the UTS Model of Learning and Learning.Futures. WIL is a vehicle to engage in public and private sector and community partnerships, design real-world relevant courses, prepare educated future professionals and strengthen graduate employability

UTS WIL Quality Framework

Work Integrated Learning (WIL) is a key component of the UTS Strategy and strengthens the idea of the civic university evidenced in UTS 2027 with strategic external partnerships, excellence in Indigenous higher education and commitment to social justice as well as personalised learning, lifetime of learning, the UTS Model of Learning and Learning.Futures. WIL is a vehicle to engage in public and private sector and community partnerships, design real-world relevant courses, prepare educated future professionals and strengthen graduate employability

Thermal noise suppression: how much does it cost?

In order to stabilize the behavior of noisy systems, confining it around a desirable state, an effort is required to suppress the intrinsic noise. This noise suppression task entails a cost. For the important case of thermal noise in an overdamped system, we show that the minimum cost is achieved when the system control parameters are held constant: any additional deterministic or random modulation produces an increase of the cost. We discuss the implications of this phenomenon for those overdamped systems whose control parameters are intrinsically noisy, presenting a case study based on the example of a Brownian particle optically trapped in an oscillating potential.Comment: 6 page

On Random Field Induced Ordering in the Classical XY Model

Consider the classical XY model in a weak random external field pointing along the $Y$ axis with strength $\epsilon$. We study the behavior of this model as the range of the interaction is varied. We prove that in any dimension $d \geq 2$ and for all $\epsilon$ sufficiently small, there is a range $L=L(\epsilon)$ so that whenever the inverse temperature $\beta$ is larger than some $\beta(\epsilon)$, there is strong residual ordering along the $X$ direction.Comment: 30 page

Thermophoresis of Brownian particles driven by coloured noise

The Brownian motion of microscopic particles is driven by the collisions with the molecules of the surrounding fluid. The noise associated with these collisions is not white, but coloured due, e.g., to the presence of hydrodynamic memory. The noise characteristic time scale is typically of the same order as the time over which the particle's kinetic energy is lost due to friction (inertial time scale). We demonstrate theoretically that, in the presence of a temperature gradient, the interplay between these two characteristic time scales can have measurable consequences on the particle long-time behaviour. Using homogenization theory, we analyse the infinitesimal generator of the stochastic differential equation describing the system in the limit where the two characteristic times are taken to zero; from this generator, we derive the thermophoretic transport coefficient, which, we find, can vary in both magnitude and sign, as observed in experiments. Furthermore, studying the long-term stationary particle distribution, we show that particles can accumulate towards the colder (positive thermophoresis) or the warmer (negative thermophoresis) regions depending on the dependence of their physical parameters and, in particular, their mobility on the temperature.Comment: 9 pages, 4 figure