Solar cell radiation response near the interface of different atomic number materials

The response of cobalt 60 irradiated N/P silicon solar cells was measured as a function of the atomic number of the medium adjacent to the cell and the direction of the gamma ray beam. The interpositioning of various thicknesses of aluminum between the adjacent material and the cell had the effect of moving the cell to various locations in an approximate monatomic numbered medium. Using this technique the solar cell response was determined at various distances from the interface for gold and beryllium. The results were compared with predictions based upon ionization chamber measurements of dose perturbations in aluminum and found to agree within five percent. Ionization chamber data was then used to estimate the influence of various base contact materials

Fibrin D-dimer, markers of coagulation activation and the risk of major ischaemic heart disease in the Caerphilly Study

We have previously reported that plasma fibrin D-dimer (a marker of turnover of cross-linked Fibrin) showed a strong and independent association with incident ischaemic heart disease (IHD) in the Caerphilly Study cohort of 1,998 men a-ed 49-65. To establish the specificity of this finding, we assayed plasma samples from this cohort with a more specific assay for fibrin D-dimer: this showed an association with incident IHD which was at least as strong and independent as that for the original assay (odds ratio, OR for top fifth compared to bottom fifth 3.79; 95% CI 1.77-8.10; p lt 0.0001). To establish potential causes of the increased fibrin turnover. we also assayed several potential markers of coagulation activation or thrombotic tendency (prothrombin fragment F1+2, thrombin- antithrombin complexes, factor VIIc, activated partial thromboplastin time [APTT] and activated protein C resistance): none of these variables were associated with incident IHD in this cohort. We suggest that further studies are required to establish the causes of increased cross-linked fibrin turnover, which is associated with incident IHD in the general population when measured by a specific assay

Procedures for estimating the effects of design and operational characteristics of jet aircraft on ground noise

Estimation procedures for effect of design and flight characteristics of jets on ground nois

Introduction to the new usability

This paper introduces the motivation for and concept of the "new usability" and positions it against existing approaches to usability. It is argued that the contexts of emerging products and systems mean that traditional approaches to usability engineering and evaluation are likely to prove inappropriate to the needs of "digital consumers." The paper briefly reviews the contributions to this special issue in terms of their relation to the idea of the "new usability" and their individual approaches to dealing with contemporary usability issues. This helps provide a background to the "new usability" research agenda, and the paper ends by posing what are argued to be the central challenges facing the area and those which lie at the heart of the proposed research agenda

No Lambda oscillations

We examine a recently published calculation which predicts an oscillatory behaviour for the decay of Lambdas produced together with a neutral kaon, and proposes a new expression for the wavelength of kaon strangeness oscillations. We modify the calculation by imposing the requirement that the interference of the K_L and K_S components of the kaon wave function occurs at a specific space-time point. With this requirement, the unusual results predicted vanish, and the conventional results are recovered.Comment: 9 pages Latex, no figures. Added Latex section omitted befor

Stratigraphy and reserves of pumiceous sand deposits in Perry's 'Asparagus Block' at Horotiu

The stratigraphic relationships between the deposits of the Hinuera Formation and the Taupo Pumice Alluvium are described over a 16 ha plot of land known as the 'Asparagus Block' at Horotiu. The Hinuera Formation is exposed at the surface at the southern end of this block, and is overlain by a wedge of Taupo Pumice Alluvium which increases in thickness from 0 to 8 m northwards across the block. Lithofacies in the Hinuera Formation are dominated by trough cross-bedded gravelly sands (lithofacies AI), with common cross-laminated sands (lithofacies B) and massive to horizontally laminated silts (lithofacies D). The pumice content of these deposits is mainly 70%. Lithofacies in the Taupo Pumice Alluvium are dominated by horizontally to inclined (tabular cross-) bedded slightly gravelly sands and sands (lithofacies G 1/2), with common occurrences of horizontally bedded to massive sandy silts (lithofacies D). The pumice content of these Taupo deposits is high, typically >80%. Cross-sections are presented showing an interpreted subsurface distribution of these lithofacies from south to north through the 'Asparagus Block'. The estimated reserve of extractable pumice sand from the block is of the order of about 400,000 to 450,000 m³

Distal occurrence of mid-Holocene Whakatane Tephra on the Chatham Islands, New Zealand, and potential for cryptotephra studies

The Whakatane Tephra, a rhyolitic tephra erupted ca. 5500 cal. BP from Okataina Volcanic Centre, central North Island, has been identified on the Chatham Islands which lie ˜900 km east of Christchurch, New Zealand. The visible tephra layer, ˜5 mm in thickness and preserved within peat on Pitt Island, was identified using both radiocarbon dating and analysis of glass shards by electron microprobe. Whakatane Tephra is the first Holocene tephra to be identified on the Chatham Islands, and it is the most distal Holocene tephra yet recorded in the New Zealand region, being ˜850 km from source. The Pitt Island occurrence extends the tephra's dispersal area markedly, by an order of magnitude, possibly to ˜300,000 km2. An estimated dispersal index (D) of approximately 105 km2 indicates that the eruption generated a very high plinian column, possibly exceeding ˜30 km in height, with strong winds blowing the ash plume southeastwards. This new discovery of distal Whakatane Tephra as a thin but visible layer strongly implies that cryptotephras are likely to be preserved on the Chatham Islands and within adjacent ocean floor sediments. Therefore the potential exists to develop enhanced cryptotephrostratigraphic records from these distal areas, which in turn would help facilitate precise correlation via tephrochronology of palaeoenvironmental records (such as NZ-INTIMATE) from mainland New Zealand, the southwest Pacific Ocean, and the Chatham Islands

Modelling the Galactic Magnetic Field on the Plane in 2D

We present a method for parametric modelling of the physical components of the Galaxy's magnetised interstellar medium, simulating the observables, and mapping out the likelihood space using a Markov Chain Monte-Carlo analysis. We then demonstrate it using total and polarised synchrotron emission data as well as rotation measures of extragalactic sources. With these three datasets, we define and study three components of the magnetic field: the large-scale coherent field, the small-scale isotropic random field, and the ordered field. In this first paper, we use only data along the Galactic plane and test a simple 2D logarithmic spiral model for the magnetic field that includes a compression and a shearing of the random component giving rise to an ordered component. We demonstrate with simulations that the method can indeed constrain multiple parameters yielding measures of, for example, the ratios of the magnetic field components. Though subject to uncertainties in thermal and cosmic ray electron densities and depending on our particular model parametrisation, our preliminary analysis shows that the coherent component is a small fraction of the total magnetic field and that an ordered component comparable in strength to the isotropic random component is required to explain the polarisation fraction of synchrotron emission. We outline further work to extend this type of analysis to study the magnetic spiral arm structure, the details of the turbulence as well as the 3D structure of the magnetic field.Comment: 18 pages, 11 figures, updated to published MNRAS versio

Some comments on embedding inflation in the AdS/CFT correspondence

The anti-de Sitter space/conformal field theory correspondence (AdS/CFT) can potentially provide a complete formulation of string theory on a landscape of stable and metastable vacua that naturally give rise to eternal inflation. As a model for this process, we consider bubble solutions with de Sitter interiors, obtained by patching together dS and Schwarzschild-AdS solutions along a bubble wall. For an interesting subclass of these solutions the bubble wall reaches spacelike infinity in the black hole interior. Including the effects of perturbations leads to a null singularity emanating from this point. Such solutions are interpreted as states in a single CFT, and are shown to be compatible with holographic entropy bounds. The construction suggests de Sitter entropy be interpreted as the total number of degrees of freedom in effective field theory, with a novel adaptive stepsize cutoff.Comment: 15 pages, 4 figures, revtex