A Study of the Production of Neutrons for Boron Neutron Capture Therapy using a Proton Accelerator

Boron Neutron Capture Therapy (BNCT) is a binary cancer therapy particularly well-suited to treating aggressive tumours that exhibit a high degree of infiltration of the surrounding healthy tissue. Such tumours, for example of the brain and lung, provide some of the most challenging problems in oncology. The first element of the therapy is boron-10 which is preferentially introduced into the cancerous cells using a carrier compound. Boron-10 has a very high capture cross-section with the other element of the therapy, thermal neutrons, resulting in the production of a lithium nucleus and an alpha particle which destroy the cell they are created in. However, a large flux of neutrons is required and until recently the only source used was a nuclear reactor. In Birmingham, studies of an existing BNCT facility using a 2.8 MeV proton beam and a solid lithium target have found a way to increase the beam power to a sufficient level to allow clinical trials, while maintaining the target solid. In this paper, we will introduce BNCT, describe the work in Birmingham and compare with other accelerator-driven BNCT projects around the World

Boomerang returns unexpectedly

Experimental study of the anisotropy in the cosmic microwave background (CMB) is gathering momentum. The eagerly awaited Boomerang results have lived up to expectations. They provide convincing evidence in favor of the standard paradigm: the Universe is close to flat and with primordial fluctuations which are redolent of inflation. Further scrutiny reveals something even more exciting however -- two hints that there may be some unforeseen physical effects. Firstly the primary acoustic peak appears at slightly larger scales than expected. Although this may be explicable through a combination of mundane effects, we suggest it is also prudent to consider the possibility that the Universe might be marginally closed. The other hint is provided by a second peak which appears less prominent than expected. This may indicate one of a number of possibilities, including increased damping length or tilted initial conditions, but also breaking of coherence or features in the initial power spectrum. Further data should test whether the current concordance model needs only to be tweaked, or to be enhanced in some fundamental way.Comment: 11 pages, 3 figures, final version accepted by Ap

What have we already learned from the CMB?

The COBE satellite, and the DMR experiment in particular, was extraordinarily successful. However, the DMR results were announced about 7 years ago, during which time a great deal more has been learned about anisotropies in the Cosmic Microwave Background (CMB). The CMB experiments currently being designed and built, including long-duration balloons, interferometers, and two space missions, promise to address several fundamental cosmological issues. We present our evaluation of what we already know, what we are beginning to learn now, and what the future may bring.Comment: 20 pages, 3 figures. Changes to match version accepted by PAS

An alternative index to ESP to explain dispersion occurring in Australian soils when Na content is low

Re-use of industrial and agricultural wastewater for irrigation can increase the concentration of potassium in soil and affect soil structure. However, investigations of clay dispersion have traditionally focused on soils with high exchangeable sodium, therefore exchangeable sodium percentage (ESP) has been used to assess soil structural stability. Currently, Australian soils have been considered non-sodic or non-dispersive when the soil ESP <6. However, a few studies have demonstrated that potassium (K) ions in the exchange complex of soil can also assist clay dispersion even when the exchangeable sodium (Na) levels are minimal. The dispersion (as turbidity) and ESP were measured on 74 Australian soils. 17 of those soils showed a considerable level of dispersion, despite ESP <4.5. In all of these soils the Na to K ratio was <1. The relationships between ESP and turbidity were poor (R2= 0.23) indicating limitations of using the ESP for identifying potentially dispersive soils when K is present on the soil exchange sites. Therefore, we used exchangeable cation ratio (ECR), as an index alternative to ESP, but which takes into account effects of exchangeable K on clay dispersion. The good correlation obtained between ECR and the parameters like turbidity and zeta potential support its use in assessing soil structural stability when the appreciable amount of K present on exchange sites

Ecology of the invasive New Zealand mud snail, Potamopyrgus antipodarum (Hydrobiidae), in a mediterranean-climate stream system

The New Zealand mud snail, Potamopyrgus antipodarum, is a widely distributed non-native species of management concern on four continents. In a southern California stream, P. antipodarum abundance, which ranged from ca. &lt;10 to nearly 150,000 snails m−2, was related to discharge and temperature patterns. Laboratory experiments indicated that P. antipodarum (1) survivorship decreased from 13 to 27°C, but its growth rate was higher at 13 and 20°C than 27°C; (2) grazing rates were similar to those of native algivores in short-term trials; (3) grazing impact was greater than that of a native hydrobiid snail in longer-term trials; (4) ingested different diatom sizes than some other grazers; (5) reduced the abundances of medium-sized and large diatoms, and several filamentous cyanobacteria and chlorophytes, while increasing the relative abundances of tough filamentous chlorophytes (e.g., Cladophora); (6) impact on other grazing invertebrates was species specific, ranging from competition to facilitation; (7) reduced the survivorship of Anaxyrus boreas tadpoles; and (8) was consumed by non-native Procambarus clarkii and naiads of Aeshna and Argia. Ecological effects of introduced P.antipodarum are subtle, occurring primarily at transitory high densities, but flow regulation may enhance their effects by eliminating high flows that reduce their population sizes

Soft power, hard news:How journalists at state-funded transnational media legitimize their work

How do journalists working for different state-funded international news organizations legitimize their relationship to the governments which support them? In what circumstances might such journalists resist the diplomatic strategies of their funding states? We address these questions through a comparative study of journalists working for international news organizations funded by the Chinese, US, UK and Qatari governments. Using 52 interviews with journalists covering humanitarian issues, we explain how they minimized tensions between their diplomatic role and dominant norms of journalistic autonomy by drawing on three – broadly shared – legitimizing narratives, involving different kinds of boundary-work. In, the first ‘exclusionary’ narrative, journalists differentiated their ‘truthful’ news reporting from the ‘false’ state ‘propaganda’ of a common Other, the Russian-funded network, RT. In the second ‘fuzzifying’ narrative, journalists deployed the ambiguous notion of ‘soft power’ as an ambivalent ‘boundary concept’, to defuse conflicts between journalistic and diplomatic agendas. In the final ‘inversion’ narrative, journalists argued that, paradoxically, their dependence on funding states gave them greater ‘operational autonomy’. Even when journalists did resist their funding states, this was hidden or partial, and prompted less by journalists’ concerns about the political effects of their work, than by serious threats to their personal cultural capital

Probing Unstable Massive Neutrinos with Current Cosmic Microwave Background Observations

The pattern of anisotropies in the Cosmic Microwave Background depends upon the masses and lifetimes of the three neutrino species. A neutrino species of mass greater than 10 eV with lifetime between 10^{13} sec and 10^{17} sec leaves a very distinct signature (due to the integrated Sachs-Wolfe effect): the anisotropies at large angles are predicted to be comparable to those on degree scales. Present data exclude such a possibility and hence this region of parameter space. For $m_\nu \simeq 30$ eV, $\tau \simeq 10^{13}$ sec, we find an interesting possibility: the Integrated Sachs Wolfe peak produced by the decaying neutrino in low-$\Omega$ models mimics the acoustic peak expected in an $\Omega = 1$ model.Comment: 5 pages, 4 figure

A Remark on the Estimation of Angular Power Spectra in the Presence of Foregrounds

It is common practice to estimate the errors on the angular power spectrum which could be obtained by an experiment with a given angular resolution and noise level. Several authors have also addressed the question of foreground subtraction using multi-frequency observations. In such observations the angular resolution of the different frequency channels is rarely the same. In this report we point out how the ``effective'' beam size and noise level change with ell in this case, and give an expression for the error on the angular power spectrum as a function of ell.Comment: 3 pages, no figures, to appear in Phys Rev

Classical Statistical Mechanics Approach to Multipartite Entanglement

We characterize the multipartite entanglement of a system of n qubits in terms of the distribution function of the bipartite purity over balanced bipartitions. We search for maximally multipartite entangled states, whose average purity is minimal, and recast this optimization problem into a problem of statistical mechanics, by introducing a cost function, a fictitious temperature and a partition function. By investigating the high-temperature expansion, we obtain the first three moments of the distribution. We find that the problem exhibits frustration.Comment: 38 pages, 10 figures, published versio