Forecasts for Low Spin Black Hole Spectroscopy in Horndeski Gravity

We investigate the prospect of using black hole spectroscopy to constrain the parameters of Horndeski gravity through observations of gravitational waves from perturbed black holes. We study the gravitational waves emitted during ringdown from black holes without hair in Horndeski gravity, demonstrating the qualitative differences between such emission in General Relativity and Horndeski theory. In particular, Quasi-Normal Mode frequencies associated with the scalar field spectrum can appear in the emitted gravitational radiation. Analytic expressions for error estimates for both the black hole and Horndeski parameters are calculated using a Fisher Matrix approach, with constraints on the `effective mass' of the Horndeski scalar field of order $\sim 10^{-17}$eV$c^{-2}$ or tighter being shown to be achievable in some scenarios. Estimates for the minimum signal-noise-ratio required to observe such a signal are also presented.Comment: Updated to match published versio

Selective removal of organics for water reclamation

Electrolysis has been investigated as a means of purifying waste water. The feasibility of the direct electrochemical oxidation of urea has been demonstrated. Urea levels were reduced from 1200 ppm to 1 ppm forming the basis for a new approach to urine purification where the only consumable is electrical energy. Preliminary estimates of the energy requirements are 270 W/hr per liter of urine. Urea oxidation rates of around 350 mg urea/hr/m2 were observed. It is anticipated that a 1 m2 geometric area of electrode could treat urine for a crew of several persons. The low levels of organic contaminants resulting from this treatment indicate that the approach may have an impact as a post treatment process. Experiments are planned to investigate this later possibility

A covariant approach to parameterised cosmological perturbations

We present a covariant formulation for constructing general quadratic actions for cosmological perturbations, invariant under a given set of gauge symmetries for a given field content. This approach allows us to analyse scalar, vector and tensor perturbations at the same time in a straightforward manner. We apply the procedure to diffeomorphism invariant single-tensor, scalar-tensor and vector-tensor theories and show explicitly the full covariant form of the quadratic actions in such cases, in addition to the actions determining the evolution of vector and tensor perturbations. We also discuss the role of the symmetry of the background in identifying the set of cosmologically relevant free parameters describing these classes of theories, including calculating the relevant free parameters for an axisymmetric Bianchi-I vacuum universe.Comment: Updated to match published versio

Design considerations for a monolithic, GaAs, dual-mode, QPSK/QASK, high-throughput rate transceiver

A monolithic, GaAs, dual mode, quadrature amplitude shift keying and quadrature phase shift keying transceiver with one and two billion bits per second data rate is being considered to achieve a low power, small and ultra high speed communication system for satellite as well as terrestrial purposes. Recent GaAs integrated circuit achievements are surveyed and their constituent device types are evaluated. Design considerations, on an elemental level, of the entire modem are further included for monolithic realization with practical fabrication techniques. Numerous device types, with practical monolithic compatability, are used in the design of functional blocks with sufficient performances for realization of the transceiver

New tests of the pp-wave correspondence.

The pp-wave/SYM correspondence is an equivalence relation, H string = Δ-J , between the hamiltonian H string of string field theory in the pp-wave background and the dilatation operator Δ in = 4 Super Yang-Mills in the double scaling limit. We calculate matrix elements of these operators in string field theory and in gauge theory. In the string theory Hilbert space we use the natural string basis, and in the gauge theory we use the basis which is isomorphic to it. States in this basis are specific linear combinations of the original BMN operators, and were constructed previously for the case of two scalar impurities. We extend this construction to incorporate BMN operators with vector and mixed impurities. This enables us to verify from the gauge theory perspective two key properties of the three-string interaction vertex of Spradlin and Volovich: (1) the vanishing of the three-string amplitude for string states with one vector and one scalar impurity; and (2) the relative minus sign in the string amplitude involving states with two vector impurities compared to that with two scalar impurities. This implies a spontaneous breaking of the 2 symmetry of the string field theory in the pp-wave background. Furthermore, we calculate the gauge theory matrix elements of Δ-J for states with an arbitrary number of scalar impurities. In all cases we find perfect agreement with the corresponding string amplitudes derived from the three-string vertex

Clouds, photolysis and regional tropospheric ozone budgets.

We use a three-dimensional chemical transport model to examine the shortwave radiative effects of clouds on the tropospheric ozone budget. In addition to looking at changes in global concentrations as previous studies have done, we examine changes in ozone chemical production and loss caused by clouds and how these vary in different parts of the troposphere. On a global scale, we find that clouds have a modest effect on ozone chemistry, but on a regional scale their role is much more significant, with the size of the response dependent on the region. The largest averaged changes in chemical budgets (±10–14%) are found in the marine troposphere, where cloud optical depths are high. We demonstrate that cloud effects are small on average in the middle troposphere because this is a transition region between reduction and enhancement in photolysis rates. We show that increases in boundary layer ozone due to clouds are driven by large-scale changes in downward ozone transport from higher in the troposphere rather than by decreases in in-situ ozone chemical loss rates. Increases in upper tropospheric ozone are caused by higher production rates due to backscattering of radiation and consequent increases in photolysis rates, mainly J(NO2). The global radiative effect of clouds on isoprene, through decreases of OH in the lower troposphere, is stronger than on ozone. Tropospheric isoprene lifetime increases by 7% when taking clouds into account. We compare the importance of clouds in contributing to uncertainties in the global ozone budget with the role of other radiatively-important factors. The budget is most sensitive to the overhead ozone column, while surface albedo and clouds have smaller effects. However, uncertainty in representing the spatial distribution of clouds may lead to a large sensitivity of the ozone budget components on regional scales

Ageing makes us dyslexic

Background: The effects of typical ageing on spoken language are well known: word production is disproportionately affected while syntactic processing is relatively well preserved. Little is known, however, about how ageing affects reading.Aims: What effect does ageing have on written language processing? In particular, how does it affect our ability to read words? How does it affect phonological awareness (our ability to manipulate the sounds of our language)?Methods & Procedures: We tested 14 people with Parkinson's disease (PD), 14 typically ageing adults (TAA), and 14 healthy younger adults on a range of background neuropsychological tests and tests of phonological awareness. We then carried out an oral naming experiment where we manipulated consistency, and a nonword repetition task where we manipulated the word-likeness of the nonwords.Outcomes & Results: We find that normal ageing causes individuals to become mildly phonologically dyslexic in that people have difficulty pronouncing nonwords. People with Parkinson's disease perform particularly poorly on language tasks involving oral naming and metalinguistic processing. We also find that ageing causes difficulty in repeating nonwords. We show that these problems are associated with a more general difficulty in processing phonological information, supporting the idea that language difficulties, including poorer reading in older age, can result from a general phonological deficit.Conclusions: We suggest that neurally this age-induced dyslexia is associated with frontal deterioration (and perhaps deterioration in other regions) and cognitively to the loss of executive processes that enable us to manipulate spoken and written language. We discuss implications for therapy and treatment

Selective removal of organics for water reclamation

Electrooxidation is a means of removing organic solutes directly from waste waters without the use of chemical expendables. The feasibility of the concept for oxidation of organic impurities common to urine, shower waters and space habitat humidity condensates was demonstrated. Electrooxidation of urine and waste water ersatz was experimentally demonstrated. The electrooxidation principle, reaction kinetics, efficiency, power, size, experimental test results and water reclamation applications are described. Process operating potentials and the use of anodic oxidation potentials that are sufficiently low to avoid oxygen formation and chloride oxidation are also described. The design of a novel electrochemical system that incorporates a proton exchange membrane (PEM) electrolyte is presented based on parametric test data and current fuel cell technology