Cooling slope casting to obtain thixotropic feedstock

Thixoforming, and related semi-solid processing routes for metallic alloys, require feedstock with a non-dendritic microstructure in the semi-solid state. The material then behaves in a thixotropic way in that, when it is sheared it flows and can be forced to fill a die and, when it is allowed to stand it thickens again. The New Rheocasting (the NRC process) is a recently developed semi-solid processing route. There are two versions of this route. In one, molten alloy is poured directly into a tilted mould and, through careful temperature control during cooling, a spheroidal semi-solid microstructure is achieved. The material in the mould is then upended into a shot sleeve and hence forced into a die. Alternatively, the molten alloy is poured onto a cooling slope and thence into a mould before processing. The aim of the work described in this paper was to develop understanding of the microstructural development during the initial stages of this process. The results for pouring A356 aluminium alloy via a cooling slope into a mould are presented

Demonstration of immune responses against devil facial tumour disease in wild Tasmanian devils

Devil facial tumour disease (DFTD) is a recently emerged fatal transmissible cancer decimating the wild population of Tasmanian devils (Sarcophilus harrisii). Biting transmits the cancer cells and the tumour develops in the new host as an allograft. The literature reports that immune escape mechanisms employed by DFTD inevitably result in host death. Here we present the first evidence that DFTD regression can occur and that wild devils can mount an immune response against the disease. Of the 52 devils tested, six had serum antibodies against DFTD cells and, in one case, prominent T lymphocyte infiltration in its tumour. Notably, four of the six devils with serum antibody had histories of DFTD regression. The novel demonstration of an immune response against DFTD in wild Tasmanian devils suggests that a proportion of wild devils can produce a protective immune response against naturally acquired DFTD. This has implications for tumour-host coevolution and vaccine development.Ruth Pye, Rodrigo Hamede, Hannah V. Siddle, Alison Caldwell, Graeme W. Knowles, Kate Swift, Alexandre Kreiss, Menna E. Jones, A. Bruce Lyons, Gregory M. Wood

`In pursuit of the Nazi mind?' the deployment of psychoanalysis in the allied struggle against Germany

This paper discusses how psychoanalytic ideas were brought to bear in the Allied struggle against the Third Reich and explores some of the claims that were made about this endeavour. It shows how a variety of studies of Fascist psychopathology, centred on the concept of superego, were mobilized in military intelligence, post-war planning and policy recommendations for ‘denazification’. Freud's ideas were sometimes championed by particular army doctors and government planners; at other times they were combined with, or displaced by, competing, psychiatric and psychological forms of treatment and diverse studies of the Fascist ‘personality’. This is illustrated through a discussion of the treatment and interpretation of the deputy leader of the Nazi Party, Rudolf Hess, after his arrival in Britain in 1941

Electron impact ionization of 1-propanol

Experimental measurements of the cations created in electron impact ionization have been undertaken for the primary isomer of propanol using a Hidden Quadrupole Mass Spectrometer (EPIC 300), with a mass resolution of 1 amu. The mass spectra recorded at an incident electron energy of 70 eV reveals the relative probability of forming 50 different cations, by either direct ionization or dissociative ionization. Individual partial ionization cross sections (PICS) for 31 different cations were measured for the first time in this work, for the incident electron energy range from 10 to 100eV. Also, appearance energies (AEs) and Wannier exponents for the 16 most intense cations formed in electron collisions with 1-propanol are reported. Where possible, those results are compared to those from an earlier investigation. Total Ionization Cross Sections (TICS) were also obtained from the sum of the measured PICS, for nearly all cations measured, and are compared to relevant data reported in the literature. In addition, as a part of this study, theoretical TICS were calculated using the Binary-encounter Bethe (BEB) and independent atom model with screening corrected additivity rule (IAM - SCAR) methods. Good agreement between current measured and calculated TICSs and corresponding earlier results was typically found

Probing the primordial power spectra with inflationary priors

We investigate constraints on power spectra of the primordial curvature and tensor perturbations with priors based on single-field slow-roll inflation models. We stochastically draw the Hubble slow-roll parameters and generate the primordial power spectra using the inflationary flow equations. Using data from recent observations of CMB and several measurements of geometrical distances in the late Universe, Bayesian parameter estimation and model selection are performed for models that have separate priors on the slow-roll parameters. The same analysis is also performed adopting the standard parameterization of the primordial power spectra. We confirmed that the scale-invariant Harrison-Zel'dovich spectrum is disfavored with increased significance from previous studies. While current observations appear to be optimally modeled with some simple models of single-field slow-roll inflation, data is not enough constraining to distinguish these models.Comment: 23 pages, 3 figures, 7 tables, accepted for publication in JCA

Inflation from Warped Space

A long period of inflation can be triggered when the inflaton is held up on the top of a steep potential by the infrared end of a warped space. We first study the field theory description of such a model. We then embed it in the flux stabilized string compactification. Some special effects in the throat reheating process by relativistic branes are discussed. We put all these ingredients into a multi-throat brane inflationary scenario. The resulting cosmic string tension and a multi-throat slow-roll model are also discussed.Comment: 39 pages; v4, added reference, to appear in JHE

An Inflationary Model in String Theory

We construct a model of inflation in string theory after carefully taking into account moduli stabilization. The setting is a warped compactification of Type IIB string theory in the presence of D3 and anti-D3-branes. The inflaton is the position of a D3-brane in the internal space. By suitably adjusting fluxes and the location of symmetrically placed anti-D3-branes, we show that at a point of enhanced symmetry, the inflaton potential V can have a broad maximum, satisfying the condition V''/V << 1 in Planck units. On starting close to the top of this potential the slow-roll conditions can be met. Observational constraints impose significant restrictions. As a first pass we show that these can be satisfied and determine the important scales in the compactification to within an order of magnitude. One robust feature is that the scale of inflation is low, H = O(10^{10}) GeV. Removing the observational constraints makes it much easier to construct a slow-roll inflationary model. Generalizations and consequences including the possibility of eternal inflation are also discussed. A more careful study, including explicit constructions of the model in string theory, is left for the future.Comment: 27 pages, LaTeX, 1 eps figure. v2: references adde

Spontaneous Creation of Inflationary Universes and the Cosmic Landscape

We study some gravitational instanton solutions that offer a natural realization of the spontaneous creation of inflationary universes in the brane world context in string theory. Decoherence due to couplings of higher (perturbative) modes of the metric as well as matter fields modifies the Hartle-Hawking wavefunction for de Sitter space. Generalizing this new wavefunction to be used in string theory, we propose a principle in string theory that hopefully will lead us to the particular vacuum we live in, thus avoiding the anthropic principle. As an illustration of this idea, we give a phenomenological analysis of the probability of quantum tunneling to various stringy vacua. We find that the preferred tunneling is to an inflationary universe (like our early universe), not to a universe with a very small cosmological constant (i.e., like today's universe) and not to a 10-dimensional uncompactified de Sitter universe. Such preferred solutions are interesting as they offer a cosmological mechanism for the stabilization of extra dimensions during the inflationary epoch.Comment: 52 pages, 7 figures, 1 table. Added discussion on supercritical string vacua, added reference

Inflation in Realistic D-Brane Models

We find successful models of D-brane/anti-brane inflation within a string context. We work within the GKP-KKLT class of type IIB string vacua for which many moduli are stabilized through fluxes, as recently modified to include `realistic' orbifold sectors containing standard-model type particles. We allow all moduli to roll when searching for inflationary solutions and find that inflation is not generic inasmuch as special choices must be made for the parameters describing the vacuum. But given these choices inflation can occur for a reasonably wide range of initial conditions for the brane and antibrane. We find that D-terms associated with the orbifold blowing-up modes play an important role in the inflationary dynamics. Since the models contain a standard-model-like sector after inflation, they open up the possibility of addressing reheating issues. We calculate predictions for the CMB temperature fluctuations and find that these can be consistent with observations, but are generically not deep within the scale-invariant regime and so can allow appreciable values for $dn_s/d\ln k$ as well as predicting a potentially observable gravity-wave signal. It is also possible to generate some admixture of isocurvature fluctuations.Comment: 39 pages, 21 figures; added references; identified parameters combining successful inflation with strong warping, as needed for consistency of the approximation

Racetrack Inflation

We develop a model of eternal topological inflation using a racetrack potential within the context of type IIB string theory with KKLT volume stabilization. The inflaton field is the imaginary part of the K\"ahler structure modulus, which is an axion-like field in the 4D effective field theory. This model does not require moving branes, and in this sense it is simpler than other models of string theory inflation. Contrary to single-exponential models, the structure of the potential in this example allows for the existence of saddle points between two degenerate local minima for which the slow-roll conditions can be satisfied in a particular range of parameter space. We conjecture that this type of inflation should be present in more general realizations of the modular landscape. We also consider `irrational' models having a dense set of minima, and discuss their possible relevance for the cosmological constant problem.Comment: 23 pages 7 figures. The final version with minor modifications, to appear in JHE