1,283 research outputs found
Aberdeen's 'Toun College': Marischal College, 1593-1623
While debate has arisen in the past two decades regarding the foundation of Edinburgh University, by contrast the foundation and early development of Marischal College, Aberdeen, has received little attention. This is particularly surprising when one considers it is perhaps the closest Scottish parallel to the Edinburgh foundation. Founded in April 1593 by George Keith, fifth Earl Marischal in the burgh of New Aberdeen ‘to do the utmost good to the Church, the Country and the Commonwealth’,1 like Edinburgh Marischal was a new type of institution that had more in common with the Protestant ‘arts colleges’ springing up across the continent than with the papally sanctioned Scottish universities of St Andrews, Glasgow and King's College in Old Aberdeen.2 James Kirk is the most recent in a long line of historians to argue that the impetus for founding ‘ane college of theologe’ in Edinburgh in 1579 was carried forward by the radical presbyterian James Lawson, which led to the eventual opening on 14 October 1583 of a liberal arts college in the burgh, as part of an educational reform programme devised and rolled out across the Scottish universities by the divine and educational reformer, Andrew Melville.
Zeroing in on more photons and gluons
We discuss radiation zeros that are found in gauge tree amplitudes for
processes involving multi-photon emission. Previous results are clarified by
examples and by further elaboration. The conditions under which such amplitude
zeros occur are identical in form to those for the single-photon zeros, and all
radiated photons must travel parallel to each other. Any other neutral particle
likewise must be massless (e.g. gluon) and travel in that common direction. The
relevance to questions like gluon jet identification and computational checks
is considered. We use examples to show how certain multi-photon amplitudes
evade the zeros, and to demonstrate the connection to a more general result,
the decoupling of an external electromagnetic plane wave in the ``null zone".
Brief comments are made about zeros associated with other gauge-boson emission.Comment: 26 page
A suspected lipofuscin storage disease of sheep associated with ingestion of the plant, Trachyandra divaricata (Jacq.) Kunth
Paresis afflicted 85 out of a flock of 770 young Merino ewes kept on old wheat lands in the western Cape during a period of drought. Many of the paretic ewes died. The vegetation was sparse and was dominated by Trachyandra divaricata. At necropsy, yellowish-brown discoloration of the grey matter throughout the brain and spinal cord and mild brown discoloration of the liver, renal cortex and lymph nodes were consistently seen.
Light microscopical examination revealed abundant, yellowish-brown pigment granules in the cytoplasm of most of the larger neurons. Similar pigment also occurred in some non-nervous tissues. Shrinkage and loss of a few randomly scattered axons were observed in the white matter of the spinal cord in 2 sheep. Histochemical and ultrastructural features of the pigment were consistent with those of lipofuscin.
T. divaricata failed to reproduce the condition when dosed to a sheep, but the paresis and pigmentation shown to be caused by the closely related plant, T. laxa, are strikingly similar. Trachyandra poisoning appears to be the first documented example in farm animals of an acquired lipofuscin storage disease involving nervous and non-nervous tissues for which a specific plant has been causally implicated.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi.
Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format
Exposure to boat noise in the field yields minimal stress response in wild reef fish
Aquatic anthropogenic noise is on the rise, with growing concern about its impact on species that are sensitive to low-frequency sounds (e.g. most fish and invertebrates). We investigated whether the reef fish Halichoeres bivittatus living in both noisy and quiet areas had differing levels of baseline stress (measured as whole-body cortisol) and whether they would exhibit a physiological stress response when exposed to boat noise playbacks. While the playback experiments significantly increased cortisol levels in fish from our experiment compared to baseline levels, there were minimal pairwise differences across treatments and no difference in baseline stress for fish living in noisy vs. quiet areas. These results may be explained by low overall auditory sensitivity, habituation to a fairly noisy environment (due to biological sounds), or that boat noise simply may not represent an immediate threat to survival in this species. These findings contrast recent studies that have shown elevated stress responses in fishes when exposed to boat noise and highlights that inter-specific differences must be considered when evaluating potential impacts of anthropogenic noise on marine life
Anomalous Chromomagnetic Moments of Quarks and Large Transverse Energy Jets
We consider the jet cross sections for gluons coupling to quarks with an
anomalous chromomagnetic moment. We then apply this to the deviation and bounds
from QCD found in the CDF and D0 Fermilab data, respectively, to find a range
of possible values for the anomalous moments. The quadratic and quartic terms
in the anomalous moments can fit to the rise of a deviation with transverse
energy. Since previous analyses have been done on the top quark total cross
section, here we assume the same moment on all quarks except the top and find
the range TeV for the
CDF data. Assuming the anomalous moment is present only on a charm or bottom
quark which is pair produced results in a range TeV. The magnitudes here are compared with anomalous magnetic moments
that could account for and found to be in the same general range, as well
as not inconsistent with LEP and SLD bounds on .Comment: REVTeX, 11 pages, 2 postscript figure
On quantum teleportation with beam-splitter-generated entanglement
Following the lead of Cochrane, Milburn, and Munro [Phys. Rev. A {\bf 62},
062307 (2000)], we investigate theoretically quantum teleportation by means of
the number-sum and phase-difference variables. We study Fock-state entanglement
generated by a beam splitter and show that two-mode Fock-state inputs can be
entangled by a beam splitter into close approximations of maximally entangled
eigenstates of the phase difference and the photon-number sum
(Einstein-Podolsky-Rosen -- EPR -- states). Such states could be experimentally
feasible with on-demand single-photon sources. We show that the teleportation
fidelity can reach near unity when such ``quasi-EPR'' states are used as the
quantum channel.Comment: 7 pages (two-column), 7 figures, submitted to Phys. Rev. A. Text
unmodified, postscript error correcte
Secure quantum key distribution using squeezed states
We prove the security of a quantum key distribution scheme based on
transmission of squeezed quantum states of a harmonic oscillator. Our proof
employs quantum error-correcting codes that encode a finite-dimensional quantum
system in the infinite-dimensional Hilbert space of an oscillator, and protect
against errors that shift the canonical variables p and q. If the noise in the
quantum channel is weak, squeezing signal states by 2.51 dB (a squeeze factor
e^r=1.34) is sufficient in principle to ensure the security of a protocol that
is suitably enhanced by classical error correction and privacy amplification.
Secure key distribution can be achieved over distances comparable to the
attenuation length of the quantum channel.Comment: 19 pages, 3 figures, RevTeX and epsf, new section on channel losse
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