A Study of Vitrified Nuclear Wasteforms by Molecular Dynamics, Electron Microscopy and Raman Spectroscopy

In this study an attempt is made to create molecular dynamics (MD) models of borate glass, alkali borosilicate glasses, and UK vitreous High Level Radioactive Wasteforms. The study also includes experimental studies of vitrified wasteforms by helium pycnometry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray florescence spectroscopy (XRF) and Raman spectroscopy. Molecular dynamics models of alkali borosilicate glasses were created using Buckingham and BHM potentials in the constant pressure and temperature ensemble. The models using BHM potentials showed more realistic boron coordination numbers than those using Buckingham potentials. However structural features such as Si-O, Li-O and Na-O nearest neighbour distances and O Si O and O B O bond angles were considered satisfactory using Buckingham potentials. SEM images showing phase separation in four different vitrified wasteforms are presented. The chemical composition of the phases were determined using SEM EDX. XRF spectroscopy was obtained from the wasteforms in powder form and show qualitative agreement with nominal compositions. Raman spectroscopy also revealed the presence of MoO4 tetrahedra in a glass environment and in phases such as CaMoO4 and Na(Gd,Nd)(MoO4)2. The presence of ruthenium, cerium and zirconium phases were also found in the Raman spectra of wasteforms. MD models of three simplified vitrified wasteforms were created using Buckingham potentials. Two models of each wasteform were created. The first models used only two-body potentials and showed MoO6 octahedra connected to borosilicate network formers. In the second model of each wasteform, an additional O Mo O three-body potential was applied. The results of the second models showed MoO4 tetrahedra detached from the borosilicate network which is a realistic feature in comparison to the experimental observations

Waved albatrosses can navigate with strong magnets attached to their head

The foraging excursions of waved albatrosses Phoebastria irrorata during incubation are ideally suited for navigational studies because they navigate between their Galápagos breeding site and one specific foraging site in the upwelling zone of Peru along highly predictable, straight-line routes. We used satellite telemetry to follow free-flying albatrosses after manipulating magnetic orientation cues by attaching magnets to strategic places on the birds' heads. All experimental, sham-manipulated and control birds, were able to navigate back and forth from Galápagos to their normal foraging sites at the Peruvian coast over 1000 km away. Birds subjected to the three treatments did not differ in the routes flown or in the duration and speed of the trips. The interpretations and implications of this result depend on which of the current suggested magnetic sensory mechanisms is actually being used by the birds

THE lMMUNE RESPONSE OF PLAICE WITH PARTICULAR EMPHASIS ON ANTIGENIC SIMULATION BY TISSUE PARASITES

Antibody responses to soluble and cellular antigens have been demonstrated in juvenile and adult plaice, Pleuronectes platessa L. A relatively strong precipitating antibody was produced to calf serum, but not to bovine serum albumin. The onset, and magnitude of antibody production was temperature dependant and physico-chemical characterisation of plaice precipitins indicated they were of the IgM class. Plaice also produced haemagglutinins, following injection of rabbit erythrocytes, with a suggestion of a heightened response upon secondary stimulation with the antigen. An evaluation was made of the humoral immune.response of the fish to three tissue parasites; Rhipidocotyle johnstonei and Cryptocotyle lingua, the metacercariae of which develop in the musculature and. connective tissue of plaice; and Trypanosoma platessae, a haemoflagellate. Elevated levels of β-globulin were detected in the sera of T. platessae infected plaice, and it is suggested that this may be associated with antibody secretion to the parasite. Further studies were made on the biology of T. platessae, including efforts to maintain the parasite, by passage, in the laboratory. Natural and experimental infections with the metacercariae of C. lingua and R. johnstonei induced a temperature dependant, precipitin response in plaice. Application of the indirect fluorescent antibody technique suggested that the functional antigens of both parasites included somatic elements, however the antigens of R. johnstonei were also clearly associated with secretory tissues. A 'natural' antibody, present in the sera of the majority of test plaice, was found to precipitate in agar gel with an antigenic extract of the nematode, Proleptus obtusus. This was considered of particular interest, as P. obtusus is a parasite specific to the dogfish and is unknown in plaice. The precipitin, first suspected of being non-specific C-reactive protein, was later characterised as 19S IgM. The nature of serological and immunological changes in fish subjected to immunisation and. parasitic infection was reviewed and discussed in relation to the findings of the present project

An Analysis of Project Evaluation Methodologies in Local Government from a Cost-benefit Perspective

The methodology used by local governments to choose among capital development projects is critically important as it affects efficient social resource allocation. This paper examines current evaluation practices in the larger American cities and assesses them in terms of cost-benefit criteria. Data is gathered through survey responses of 123 project evaluators from the various cities.Master of Public AdministrationPublic AdministrationUniversity of Michigan-Flinthttps://deepblue.lib.umich.edu/bitstream/2027.42/143484/1/Barrie.pd

Education and software engineering : Ten years of progress towards a recognised professional discipline

The discipline of Software Engineering has a history dating back to 1968. However, it is only during the last ten years that real efforts have been made to address it as a profession with appropriate educational support at university levels. The achievements and failures regarding movements in the US towards professionalism in the latter half of the 1990s are first considered. Then parallel and subsequent activities that have taken place on a broader front under the auspices of the International Federation for Information Processing (IFIP) are reported. The framework that the IFIP work has produced is then used in an evaluation of international progress over a ten-year period. Finally a summary of remaining challenges is given.2nd IFIP Conference on the History of Computing and EducationRed de Universidades con Carreras en Informática (RedUNCI

A novel calibration strategy for laser ablation ICP-MS

Sample introduction by laser ablation has many desirable features: reduction of the time involved in sample pre-analysis processing, avoiding the use of hazardous reagents and reducing the risk of contamination by reagent impurities. It is also possible to produce spatial analytical profiles across small sections of samples. Laser spots of <10 µm diameter are possible With the latest commercial instrumentation. Additionally, for plasma spectrometry, the presence of molecular species derived from the plasma gases and the solvent vapour results in interferences, particularly for elements with an atomic mass of less than 80. Sampling with a laser removes the need for a solvent. The type of laser used for sampling is an important consideration. Ultraviolet lasers give better coupling between the laser and sample with ablation being mainly photochemical in nature. With infrared lasers, coupling with some samples is inefficient and is generally thermal m nature leading to poor crater definition. Calibration is one of the main difficulties associated with quantitative analysis by laser ablation. The majority of papers associated with the use of lasers for solid sampling give reference to the difficulty of reproducible calibration and in particular the lack of matrix matched standards The most commonly used calibration method to date involves the use of the National Institute of Standards and Technology (NIST) standard reference materials, particularly the 600 series glass standards. The disadvantages associated with these standards are: the analyst has no control over the elemental make up of the standard, they are relatively expensive and most importantly the matrix is fixed and cannot be matched to the sample. This thesis describes a calibration technique based on the ablation of aqueous standards. Water is transparent to the commonly used UV laser wavelengths, 193,248 and 266 nm resulting in poor energy coupling between the laser and the aqueous standard. The addition of a photo-stable chromophore results in modification of the standards absorption coefficient and enables them to mimic the behaviour of solid samples. the benefit of such standards is that they are easy to produce in any analytical laboratory. The elemental and matrix composition can be controlled by the analyst. The standards also offer the advantage of a constantly renewable surface. Initial work involved design and set-up of an optical system and laser to couple the laser with an ICP-MS. Poly( sodium 4-styrene-sulphonate) was identified as a suitable chromophore. The main criteria for the additive being that it absorbed at the excimer laser wavelengths and had an acceptable lifetime to allow adequate analytical data to be generated Investigation into the characteristics of the chromophore including effect of concentration, laser energy and laser frequency were investigated. Calibration and validation of the aqueous calibration technique was demonstrated by comparison with NIST standard reference materials. The absorption coefficient of the aqueous standard was matched with that of the NIST reference material. Both samples were then analysed by ICP-MS. The count rates observed were initially found to be similar for both samples, however the signal for the aqueous standard remained stable but the signal for the NIST glass decreased. This was thought to be due to the laser channelling into the solid sample causing loss of focus. The aqueous standard in effect provides a constantly renewable surface and no loss of focus. An internal standard was used to correct for the differing sensitivities obtained. The final part of the work involved application of the calibration method to two biological matrices: Bone samples from patients with osteoporosis and porcine liver samples. Elemental profiles across the samples are presented which are in general agreement with the expected and certified concentrations

The implications of a changing climate on agricultural land classification in England and Wales

The agricultural land classification (ALC) of England and Wales is a formal method of assessing the quality of agricultural land and guiding future land use. It assesses several soil, site and climate criteria and classifies land according to whichever is the most limiting. A common approach is required for calculating the necessary agroclimatic parameters over time in order to determine the effects of changes in the climate on land grading. In the present paper, climatic parameters required by the ALC classification have been re-calculated from a range of primary climate data, available from the Meteorological Office's UKCP09 historical dataset, provided as 5 km rasters for every month from 1914 to 2000. Thirty-year averages of the various agroclimatic properties were created for 1921–50, 1931–60, 1941–70, 1951–80, 1961–90 and 1971–2000. Soil records from the National Soil Inventory on a 5 km grid across England and Wales were used to determine the required soil and site parameters for determining ALC grade. Over the 80-year period it was shown that the overall climate was coolest during 1951–80. However, the area of land estimated in retrospect as ‘best and most versatile (BMV) land’ (Grades 1, 2 and 3a) probably peaked in the 1951–80 period as the cooler climate resulted in fewer droughty soils, more than offsetting the land which was downgraded by the climate being too cold. Overall there has been little change in the proportions of ALC grades among the six periods once all 10 factors (climate, gradient, flooding, texture, depth, stoniness, chemical, soil wetness, droughtiness and erosion) are taken into account. This is because it is rare for changes in climate variables all to point in the same direction in terms of ALC. Thus, a reduction in rainfall could result in higher grades in wetter areas but lead to lower classification in drier areas