42 resultados para B3 field site
Resumo:
This is an interim report on research carried out at the intertidal site of Peterstone Great Wharf, located on the Wentlooge Levels, c. 7 km east of Cardiff. The project is the first detailed survey and excavation of a site originally recorded in 1996-7 as part of a larger survey of the intertidal zone from Cardiff to the Second Severn Crossing. The 1997 survey produced important evidence for prehistoric human activity preserved within four palaeochannels. Significant erosion has taken place since then. A new survey of the foreshore has identified additional palaeochannels not seen in 1997 which form part of a more complex system of inter-cutting channels, many containing wood structures including short lines of timbers on the channel edge. Artefacts include a wooden axe handle, antler artefacts, an animal bone assemblage and some pottery of Beaker and Bronze Age date. The finds are thought to derive from a nearby, possibly eroded, settlement. The channels have trapped artefacts and preserved evidence of a range of activities, including what are interpreted as possible boat landings and fishing structures.
Resumo:
In the last decade, a vast number of land surface schemes has been designed for use in global climate models, atmospheric weather prediction, mesoscale numerical models, ecological models, and models of global changes. Since land surface schemes are designed for different purposes they have various levels of complexity in the treatment of bare soil processes, vegetation, and soil water movement. This paper is a contribution to a little group of papers dealing with intercomparison of differently designed and oriented land surface schemes. For that purpose we have chosen three schemes for classification: i) global climate models, BATS (Dickinson et al., 1986; Dickinson et al., 1992); ii) mesoscale and ecological models, LEAF (Lee, 1992) and iii) mesoscale models, LAPS (Mihailović, 1996; Mihailović and Kallos, 1997; Mihailović et al., 1999) according to the Shao et al. (1995) classification. These schemes were compared using surface fluxes and leaf temperature outputs obtained by time integrations of data sets derived from the micrometeorological measurements above a maize field at an experimental site in De Sinderhoeve (The Netherlands) for 18 August, 8 September, and 4 October 1988. Finally, comparison of the schemes was supported applying a simple statistical analysis on the surface flux outputs.
Resumo:
Coronal mass ejections (CMEs) can be continuously tracked through a large portion of the inner heliosphere by direct imaging in visible and radio wavebands. White light (WL) signatures of solar wind transients, such as CMEs, result from Thomson scattering of sunlight by free electrons and therefore depend on both viewing geometry and electron density. The Faraday rotation (FR) of radio waves from extragalactic pulsars and quasars, which arises due to the presence of such solar wind features, depends on the line-of-sight magnetic field component B ∥ and the electron density. To understand coordinated WL and FR observations of CMEs, we perform forward magnetohydrodynamic modeling of an Earth-directed shock and synthesize the signatures that would be remotely sensed at a number of widely distributed vantage points in the inner heliosphere. Removal of the background solar wind contribution reveals the shock-associated enhancements in WL and FR. While the efficiency of Thomson scattering depends on scattering angle, WL radiance I decreases with heliocentric distance r roughly according to the expression Ir –3. The sheath region downstream of the Earth-directed shock is well viewed from the L4 and L5 Lagrangian points, demonstrating the benefits of these points in terms of space weather forecasting. The spatial position of the main scattering site r sheath and the mass of plasma at that position M sheath can be inferred from the polarization of the shock-associated enhancement in WL radiance. From the FR measurements, the local B ∥sheath at r sheath can then be estimated. Simultaneous observations in polarized WL and FR can not only be used to detect CMEs, but also to diagnose their plasma and magnetic field properties.
Resumo:
Of all the various definitions of the polar cap boundary that have been used in the past, the most physically meaningful and significant is the boundary between open and closed field lines. Locating this boundary is very important as it defines which regions and phenomena are on open field lines and which are on closed. This usually has fundamental implications for the mechanisms invoked. Unfortunately, the open-closed boundary is usually very difficult to identify, particularly where it maps to an active reconnection site. This paper looks at the topological reconnection classes that can take place, both at the magnetopause and in the cross-tail current sheet and discusses the implications for identifying the open-closed boundary when reconnection is giving velocity filter dispersion of signatures. On the dayside, it is shown that the dayside boundary plasma sheet and low-latitude boundary layer precipitations are well explained as being on open field lines, energetic ions being present because of reflection of central plasma sheet ions off the two Alfvén waves launched by the reconnection site (the outer one of which is the magnetopause). This also explains otherwise anomalous features of the dayside convection pattern in the cusp region. On the nightside, similar considerations place the open-closed boundary somewhat poleward of the velocity-dispersed ion structures which are a signature of the plasma sheet boundary layer ion flows in the tail.
Resumo:
We analyze of ion populations observed by the NOAA-12 satellite within dayside auroral transients. The data are matched with an open magnetopause model which allows for the transmission of magnetosheath ions across one or both of the two Alfvén waves which emanate from the magnetopause reconnection site. It also allows for reflection and acceleration of ions of magnetospheric origin by these waves. From the good agreement found between the model and the observations, we propose that the events and the low-latitude boundary precipitation are both on open field lines.
Resumo:
We present evidence for the acceleration of magnetospheric ions by reflection off two Alfvén waves, launched by the reconnection site into the inflow regions on both sides of the reconnecting magnetopause. The “exterior” wave stands in the inflow from the magnetosheath and is the magnetopause, in the sense that the majority of the field rotation occurs there. The other, “interior” wave stands in the inflow region on the magnetospheric side of the boundary. The population reflected by the interior wave is the more highly energized of the two and appears at low altitudes on open field lines, immediately equatorward of the cusp precipitation. In addition, we identify the population of magnetosheath ions transmitted across the exterior Alfvén wave, as well as a population of magnetospheric ions which are accelerated, after transmission through the interior wave, by reflection off the exterior wave. The ion populations near the X line are modeled and, with allowance for time-of-flight effects, are also derived from observations in the dayside auroral ionosphere. Agreement between observed and theoretical spectra is very good and the theory also explains the observed total fluxes and average energies of the precipitations poleward of the open/closed field line boundary. The results offer a physical interpretation of all the various classifications of precipitation into the dayside ionosphere (central plasma sheet, dayside boundary plasma sheet, void, low-latitude boundary layer, cusp, and mantle) and allow the conditions in both the magnetosphere and the magnetosheath adjacent to the X line to be studied.
Resumo:
Longitudinal flow bursts observed by the European Incoherent Scatter (EISCAT) radar, in association with dayside auroral transients observed from Svalbard, have been interpreted as resulting from pulses of enhanced reconnection at the dayside magnetopause. However, an alternative model has recently been proposed for a steady rate of magnetopause reconnection, in which the bursts of longitudinal flow are due to increases in the field line curvature force, associated with the By component of the magnetosheath field. We here evaluate these two models, using observations on January 20, 1990, by EISCAT and a 630-nm all-sky camera at Ny Ålesund. For both models, we predict the behavior of both the dayside flows and the 630-nm emissions on newly opened field lines. It is shown that the signatures of steady reconnection and magnetosheath By changes could possibly resemble the observed 630-nm auroral events, but only for certain locations of the observing site, relative to the ionospheric projection of the reconnection X line: however, in such cases, the flow bursts would be seen between the 630-nm transients and not within them. On the other hand, the model of reconnection rate pulses predicts that the flows will be enhanced within each 630-nm transient auroral event. The observations on January 20, 1990, are shown to be consistent with the model of enhanced reconnection rate pulses over a background level and inconsistent with the effects of periodic enhancements of the magnitude of the magnetosheath By component. We estimate that the reconnection rate within the pulses would have to be at least an order of magnitude larger than the background level between the pulses.
Resumo:
The large pine weevil, Hylobius abietis, is a serious pest of reforestation in northern Europe. However, weevils developing in stumps of felled trees can be killed by entomopathogenic nematodes applied to soil around the stumps and this method of control has been used at an operational level in the UK and Ireland. We investigated the factors affecting the efficacy of entomopathogenic nematodes in the control of the large pine weevil spanning 10 years of field experiments, by means of a meta-analysis of published studies and previously unpublished data. We investigated two species with different foraging strategies, the ‘ambusher’ Steinernema carpocapsae, the species most often used at an operational level, and the ‘cruiser’ Heterorhabditis downesi. Efficacy was measured both by percentage reduction in numbers of adults emerging relative to untreated controls and by percentage parasitism of developing weevils in the stump. Both measures were significantly higher with H. downesi compared to S. carpocapsae. General linear models were constructed for each nematode species separately, using substrate type (peat versus mineral soil) and tree species (pine versus spruce) as fixed factors, weevil abundance (from the mean of untreated stumps) as a covariate and percentage reduction or percentage parasitism as the response variable. For both nematode species, the most significant and parsimonious models showed that substrate type was consistently, but not always, the most significant variable, whether replicates were at a site or stump level, and that peaty soils significantly promote the efficacy of both species. Efficacy, in terms of percentage parasitism, was not density dependent.
Resumo:
The Chiado’s fire that affected the city centre of Lisbon (Portugal) occurred on 25th August 1988 and had a significant human and environmental impact. This fire was considered the most significant hazard to have occurred in Lisbon city centre after the major earthquake of 1755. A clear signature of this fire is found in the atmospheric electric field data recorded at Portela meteorological station about 8 km NE from the site where the fire started at Chiado. Measurements were made using a Benndorf electrograph with a probe at 1 m height. The atmospheric electric field reached 510 V/m when the wind direction was coming from SW to NE, favourable to the transport of the smoke plume from Chiado to Portela. Such observations agree with predictions using Hysplit air mass trajectory modelling and have been used to estimate the smoke concentration to be ~0.4 mg/m3. It is demonstrated that atmospheric electric field measurements were therefore extremely sensitive to Chiado’s fire. This result is of particular current interest in using networks of atmospheric electric field sensors to complement existing optical and meteorological observations for fire monitoring.
Resumo:
In England, appraisals of the financial viability of development schemes have become an integral part of planning policy-making, initially in determining the amount of planning obligations that might be obtained via legal agreements (known as Section 106 agreements) and latterly as a basis for establishing charging schedules for the Community Infrastructure Levy (CIL). Local planning authorities set these policies on an area-wide basis but ultimately development proposals require consent on a site-by-site basis. It is at this site-specific level that issues of viability are hotly contested. This paper examines case documents, proofs of evidence and decisions from a sample of planning disputes in order to address major issues within development viability, the application of the models and the distribution of the development gain between the developer, landowner and community. The results have specific application to viability assessment in England and should impact on future policy and practice guidance in this field. They also have relevance to other countries that incorporate assessments of economic viability in their planning systems.
Resumo:
Elucidating the biological and biochemical roles of proteins, and subsequently determining their interacting partners, can be difficult and time consuming using in vitro and/or in vivo methods, and consequently the majority of newly sequenced proteins will have unknown structures and functions. However, in silico methods for predicting protein–ligand binding sites and protein biochemical functions offer an alternative practical solution. The characterisation of protein–ligand binding sites is essential for investigating new functional roles, which can impact the major biological research spheres of health, food, and energy security. In this review we discuss the role in silico methods play in 3D modelling of protein–ligand binding sites, along with their role in predicting biochemical functionality. In addition, we describe in detail some of the key alternative in silico prediction approaches that are available, as well as discussing the Critical Assessment of Techniques for Protein Structure Prediction (CASP) and the Continuous Automated Model EvaluatiOn (CAMEO) projects, and their impact on developments in the field. Furthermore, we discuss the importance of protein function prediction methods for tackling 21st century problems.
Resumo:
BACKGROUND: Succinate dehydrogenase inhibitor fungicides are important in the management of Zymoseptoria tritici in wheat. New active ingredients from this group of fungicides have been introduced recently and are widely used. Because the fungicides act at a single enzyme site, resistance development in Z. tritici is classified as medium-to-high risk. RESULTS: Isolates from Irish experimental plots in 2015 were tested against the SDHI penthiopyrad during routine monitoring. The median of the population was approximately 2 x less sensitive than the median of the baseline population. Two of the 93 isolates were much less sensitive to penthiopyrad than least sensitive of the baseline isolates. These isolates were also insensitive to most of commercially available SDHIs. Analysis of the succinate dehydrogenase coding genes confirmed the presence of the substitutions SdhC-H152R and SdhD-R47W in the very insensitive isolates. CONCLUSION: This is the first report showing that the SdhC-H152R mutation detected in laboratory mutagenesis studies also exists in the field. The function and relevance of this mutation, combined with SdhD-R47W, still needs to be determined.