Some Palaeomagnetic Measurements in Antarctica

... The activity engendered by the International Geophysical Year 1957-8 provided an opportunity to obtain suitable rock specimens from the antarctic continent, and the author was able to visit two localities in Victoria Land. At Cape Hallett (72°S., 171°E.) the prominent Cenozoic volcanics were sampled, but the Palaeozoic sediments of the Robertson Bay group, quite highly metamorphosed in this region, were rejected as unlikely to provide reliable data on the ancient magnetic field. In the Ferrar Glacier region (78°S., 161°E.), samples were collected from the late Palaeozoic / early Mesozoic Beacon sandstone, and from the extensive Mesozoic dolerite sills intrusive within the sandstone series. The remanent magnetizations of the rocks collected were measured at King's College, University of Durham. A sensitive astatic magnetometer was employed to measure the weaker magnetization of the sedimentary rocks and a simpler instrument was used for the more strongly magnetized igneous specimens. Mean directions of magnetization and corresponding pole positions were calculated, and the 95 per cent level of confidence estimated in the usual way. ... Uncertainties in geological age and - for the Cape Hallett lavas - of the sampling procedure, preclude any precise statements. However, some general conclusions may be drawn. Here, as elsewhere, reversed directions of magnetization occur and may be interpreted as representative of reversals of the main magnetic field of the earth. Cenozoic rocks appear to have been magnetized in a mean field not essentially different from that of a geocentric dipole aligned with the present axis. Older rocks are magnetized in a direction significantly different from that of the present mean magnetic field. This may be interpreted as evidence of polar wandering, implying a polar movement of some 30 degrees since the later part of the Mesozoic era. The data are perhaps too sparse to admit of a discussion of continental drift

Episteme and Doxa: Some Reflections on Eleatic and Heraclitean Themes in Plato

I point out some unnoticed features of the interrelationships between episteme and doxa which help to explain some difficult texts and which I take to be archai for their definitive accounts. Much turns on how \u27is\u27 is to be understood, and whether or not it can be said to have different senses

The \u27Third Man Argument\u27 and the Text of the Parmenides

I attempt to show that the \u27Large\u27 argument of Parmenides 132 must be understood as part of the attempt to clarify Socrates\u27 response to Zeno. The threat to that response is to the requirement that each form be one and not many. But it is also a threat to the very idea of having a share of a form. In context, the argument is underbrush clearing, getting an unworkable idea out of the way

Fabrication of free-standing ordered fluorescent polymer nanofibres by electrospinning

The authors are grateful to the Engineering and Physical Sciences Research Council for financial support.We demonstrate a static fabrication approach to make free-standing ordered arrays of fluorescent nanofibres through control of the transverse electrospinning field. The alignment and the density of the nanofibre arrays are optimised by careful design of both the source and collector electrode geometries which can control the transverse electric field over the full path of the jet. In doing so, we fabricate suspended fluorescent nanofibres with an aspect ratio of 10(4), and with a substantially increased density and order parameter (by a factor of similar to 10 compared to random deposition). Electrostatic modelling suggests that the field distribution of the component is the main contribution to the ordering between the plates. This method offers increased efficiency for the creation of ordered fibres collected over a small area and the characterisation of their photoluminescent properties.Publisher PDFPeer reviewe

Signature of nearly icosahedral structures in liquid and supercooled liquid Copper

A growing body of experiments display indirect evidence of icosahedral structures in supercooled liquid metals. Computer simulations provide more direct evidence but generally rely on approximate interatomic potentials of unproven accuracy. We use first-principles molecular dynamics simulations to generate realistic atomic configurations, providing structural detail not directly available from experiment, based on interatomic forces that are more reliable than conventional simulations. We analyze liquid copper, for which recent experimental results are available for comparison, to quantify the degree of local icosahedral and polytetrahedral order

b anti-b Higgs production at the LHC: Yukawa corrections and the leading Landau singularity

At tree-level Higgs production in association with a b-quark pair proceeds through the small Yukawa bottom coupling in the Standard Model. Even in the limit where this coupling vanishes, electroweak one-loop effects, through the top-Higgs Yukawa coupling in particular, can still trigger this reaction. This contribution is small for Higgs masses around 120GeV but it quickly picks up for higher Higgs masses especially because the one-loop amplitude develops a leading Landau singularity and new thresholds open up. These effects can be viewed as the production of a pair of top quarks which rescatter to give rise to Higgs production through WW fusion. We study the leading Landau singularity in detail. Since this singularity is not integrable when the one-loop amplitude is squared, we regulate the cross section by taking into account the width of the internal top and W particles. This requires that we extend the usual box one-loop function to the case of imaginary masses. We show how this can be implemented analytically in our case. We study in some detail the cross section at the LHC as a function of the Higgs mass and show how some distributions can be drastically affected compared to the tree-level result.Comment: 48 pages, 20 figures. Phys.Rev.D accepted version. Conclusions unchanged, minor changes and references adde