A Search for Line Shape and Depth Variations in 51 Pegasi and tau Bootis

Spectroscopic observations of 51 Pegasi and tau Bootis show no periodic changes in the shapes of their line profiles; these results for 51 Peg are in significant conflict with those reported by Gray & Hatzes. Our detection limits are small enough to rule out nonradial pulsations as the cause of the variability in tau Boo, but not in 51 Peg. The absence of line shape changes is consistent with these stars' radial velocity variability arising from planetary mass companions.

Resonance Raman and surface-enhanced resonance Raman studies of polymer-modified electrodes which mimic heme enzymes

Iron-5,10,15,20-tetraphenylporphyrin (FeTPP) has been incorporated into films of a coordinating hydrogel polymer support medium, poly(gamma-ethyl-L-glutamate) (PEG) functionalised with imidazole pendant arms (PEG-Im), and studied in situ on silver electrodes using a combination of both resonance Raman (RR) and surface-enhanced resonance Raman (SERR) spectroscopy. The SERR spectra give information on the portion of the film close to the electrode surface while RR spectra probe the

Hydraulic Subsurface Measurements and Hydrodynamic Modeling as Indicators for Groundwater Flow Systems in the Rotondo Granite, Central Alps (Switzerland)

Regional groundwater flow in high mountainous terrain is governed by a multitude of factors such as geology, topography, recharge conditions, structural elements such as fracturation and regional fault zones as well as man-made underground structures. By means of a numerical groundwater flow model, we consider the impact of deep underground tunnels and of an idealized major fault zone on the groundwater flow systems within the fractured Rotondo granite. The position of the free groundwater table as response to the above subsurface structures and, in particular, with regard to the influence of spatial distributed groundwater recharge rates is addressed. The model results show significant unsaturated zones below the mountain ridges in the study area with a thickness of up to several hundred metres. The subsurface galleries are shown to have a strong effect on the head distribution in the model domain, causing locally a reversal of natural head gradients. With respect to the position of the catchment areas to the tunnel and the corresponding type of recharge source for the tunnel inflows (i.e. glaciers or recent precipitation), as well as water table elevation, the influence of spatial distributed recharge rates is compared to uniform recharge rates. Water table elevations below the well exposed high-relief mountain ridges are observed to be more sensitive to changes in groundwater recharge rates and permeability than below ridges with less topographic relief. In the conceptual framework of the numerical simulations, the model fault zone has less influence on the groundwater table position, but more importantly acts as fast flow path for recharge from glaciated areas towards the subsurface galleries. This is in agreement with a previous study, where the imprint of glacial recharge was observed in the environmental isotope composition of groundwater sampled in the subsurface galleries. Copyright © 2012 John Wiley & Sons, Ltd.

Experimental studies of near-surface temperature cycling and surface wetting of stone and its implications for salt weathering

It has long been accepted that thermal and moisture regimes within stonework exert a major influence upon patterns of salt movement and, subsequently, the type and severity of salt-induced decay. For example, it is suggested that slow drying is more likely to bring dissolved salts to the surface, whereas rapid drying could result in the retention of some salt at or near the frequent wetting depth. In reality however, patterns of heating, cooling and surface wetting regimes that drive them – are complex and inconsistent responses to a wide range of environmental controls. As a first step to understanding the complexity of these relationships, this paper reports a series of experiments within a climatic cabinet designed to replicate the effects of short-term temperature fluctuations on the surface and sub-surface temperature regimes of a porous Jurassic limestone, and how they are influenced by surface wetting, ambient temperature and surface airflow. Preliminary results confirm the significance of very steep temperature/stress gradients within the outer centimetre or less of exposed stone under short-duration cycles of heating and cooling. This is important because this is the zone in which many stone decay processes, particularly salt weathering, operate, these processes invariably respond to temperature and moisture fluctuations, and short-term interruptions to insolation could, for example,
trigger these fluctuations on numerous occasions over a day. The data also indicate that there are complex patterns of temperature reversal with depth that are influenced in their intensity and location by surface wetting and moisture penetration, airflow across the surface and ambient air temperature. The presence of multiple temperature reversals and their variation over the course of heating and cooling phases belies previous assumtions of smooth, exponential increases and decreases in subsurface temperatures in response, for example to diurnal patterns of heating and cooling

Surface energy and surface proton order of the ice Ih basal and prism surfaces

Density-functional theory (DFT) is used to examine the basal and prism surfaces of ice Ih. Similar surface energies are obtained for the two surfaces; however, in each case a strong dependence of the surface energy on surface proton order is identified. This dependence, which can be as much as 50% of the absolute surface energy, is significantly larger than the bulk dependence (< 1%) on proton order, suggesting that the thermodynamic ground state of the ice surface will remain proton ordered well above the bulk order-disorder temperature of about 72 K. On the basal surface this suggestion is supported by Monte Carlo simulations with an empirical potential and solution of a 2D Ising model with nearest neighbor interactions taken from DFT. Order parameters that define the surface energy of each surface in terms of nearest neighbor interactions between dangling OH bonds (those which point out of the surface into vacuum) have been identified and are discussed. Overall, these results suggest that proton order-disorder effects have a profound impact on the stability of ice surfaces and will most likely have an effect on ice surface reactivity as well as ice crystal growth and morphology. S Supplementary data are available from stacks.iop.org/JPhysCM/22/074209/mmedia

Surface Energy and Surface Proton Order of Ice Ih

Ice Ih is comprised of orientationally disordered water molecules giving rise to positional disorder of the hydrogen atoms in the hydrogen bonded network of the lattice. Here we arrive at a first principles determination of the surface energy of ice Ih and suggest that the surface of ice is significantly more proton ordered than the bulk. We predict that the proton order-disorder transition, which occurs in the bulk at similar to 72 K, will not occur at the surface at any temperature below surface melting. An order parameter which defines the surface energy of ice Ih surfaces is also identified.

Changing shape and shifting boundaries - the media portrayal of probation in Ireland

Literature on the media representation of probation highlights that probation as a ‘brand’ and concept is poorly understood and lacks public visibility. This has implications for its legitimacy and credibility. In this article we explore probation’s visibility in one country, the Republic of Ireland, through a critical analysis of print media representations of probationover a 12-year period (2001 to 2012). While our study finds that the majority of the coverage of probation was either positive or neutral in tone, we note a recent shift towards a more negative tone that we argue is reflective of the changing shape of the penal-probation boundaries. These changes are linked to resourcing of the criminal justice system and have implications for the public perception of probation.

Influence of surface structures, subsurface carbon and hydrogen, and surface alloying on the activity and selectivity of acetylene hydrogenation on Pd surfaces: A density functional theory study

The selective hydrogenation of acetylene to ethylene on several Pd surfaces (Pd(111), Pd(100), Pd(211), and Pd(211)-defect) and Pd surfaces with subsurface species (carbon and hydrogen) as well as a number of Pd-based alloys (Pd-M/Pd(111) and Pd-M/Pd(211) (M = Cu, Ag and Au)) are investigated using density functional theory calculations to understand both the acetylene hydrogenation activity and the selectivity of ethylene formation. All the hydrogenation barriers are calculated, and the reaction rates on these surfaces are obtained using a two-step model. Pd(211) is found to have the highest activity for acetylene hydrogenation while Pd(100) gives rise to the lowest activity. In addition, more open surfaces result in over-hydrogenation to form ethane, while the close-packed surface (Pd(111)) is the most selective. However, we also find that the presence of subsurface carbon and hydrogen significantly changes the reactivity and selectivity of acetylene toward hydrogenation on Pd surfaces. On forming surface alloys of Pd with Cu, Ag and Au, the selectivity for ethylene is also found to be changed. A new energy decomposition method is used to quantitatively analyze the factors in determining the changes in selectivity. These surface modifiers are found to block low coordination unselective sites, leading to a decreased ethane production. (C) 2013 The Authors. Published by Elsevier Inc. All rights reserved.

An Integrated Approach to Quantifying Groundwater and Surface Water Contributions of Stream Flow

The management of water resources in Ireland prior to the Water Framework Directive (WFD) has focussed on surface water and groundwater as separate entities. A critical element to the successful implementation of the
WFD is to improve our understanding of the interaction between the two and flow mechanisms by which groundwaters discharge to surface waters. An improved understanding of the contribution of groundwater to surface water is required for the classification of groundwater body status and the determination of groundwater quality thresholds. The results of the study will also have a wider application to many areas of the WFD.
A subcommittee of the WFD Groundwater Working Group (GWWG) has been formed to develop a methodology to estimate the groundwater contribution to Irish Rivers. The group has selected a number of analytical techniques to quantify components of stream flow in an Irish context (Master Recession Curve, Unit Hydrograph, Flood Studies Report methodologies and
hydrogeological analytical modelling). The components of stream flow that can be identified include deep groundwater, intermediate and overland. These analyses have been tested on seven pilot catchments that have a variety of hydrogeological settings and have been used to inform and constrain a mathematical model. The mathematical model used was the NAM (NedbØr-AfstrØmnings-Model) rainfall-runoff model which is a module of DHIs MIKE 11 modelling suite. The results from these pilot catchments have been used to develop a decision model based on catchment descriptors from GIS datasets for the selection of NAM parameters. The datasets used include the mapping of aquifers, vulnerability and subsoils, soils, the Digital Terrain Model, CORINE and lakes. The national coverage of the GIS datasets has allowed the extrapolation of the mathematical model to regional catchments across Ireland.

Homologous size-extension of hybrid vanadate capsules – solid state structures, solution stability and surface deposition

The dimensions and cavity sizes of the molecular capsules with the general formula [V₁₀O₁₈L₄]¹⁰⁻ can be controlled modularly through the nature of the bifunctional, rigid organophosphonate ligands L¹ and L² (L¹ = bis(4-phosphonatophenyl)ethyne and L² = bis(4-phosphonatophenyl)butadiyne); the solution stability of the molecular entities as demonstrated by ESI-MS studies permits their assembly on the Au(111) surface on a sub-monolayer scale giving rise to a 2D supramolecular structure that is comparable to the packing arrangements of the capsules in the crystal structures.

Contrasting damage characteristics in direct incidence and surface plasmon mediated single-shot laser ablation of aluminium films

Thin, oxidised Al films grown an one face of fused silica prisms are exposed. tinder ambient conditions, to single shots from an excimer laser operating at wavelength 248 nm. Preliminary characterisation of the films using attenuated total reflection yields optical and thickness data for the Al and Al oxide layers; this step facilitates the subsequent, accurate tuning of the excimer laser pulse to the: surface plasmon resonance at the Al/(oxide)/air interface and the calculation of the fluence actually absorbed by the thin film system. Ablation damage is characterised using scanning electron, and atomic force microscopy. When the laser pulse is incident, through the prism on the sample at less than critical angle, the damage features are molten in nature with small islands of sub-micrometer dimension much in evidence, a mechanism of film melt-through and subsegment blow-off due to the build up of vapour pressure at the substrate/film interface is appropriate. By contrast, when the optical input is surface plasmon mediated, predominately mechanical damage results with the film fragmenting into large flakes of dimensions on the order of 10 mu m. It is suggested that the ability of surface plasmons to transport energy leads to enhanced, preferential absorption of energy at defect sites causing stress throughout the film which exceeds the ultimate tensile stress for the film: this in turn leads to film break-up before melting can onset. (C) 1998 Elsevier Science B.V.