4,190 research outputs found
Complete quantization of a diffeomorphism invariant field theory
In order to test the canonical quantization programme for general relativity
we introduce a reduced model for a real sector of complexified Ashtekar gravity
which captures important properties of the full theory. While it does not
correspond to a subset of Einstein's gravity it has the advantage that the
programme of canonical quantization can be carried out completely and
explicitly, both, via the reduced phase space approach or along the lines of
the algebraic quantization programme. This model stands in close correspondence
to the frequently treated cylindrically symmetric waves. In contrast to other
models that have been looked at up to now in terms of the new variables the
reduced phase space is infinite dimensional while the scalar constraint is
genuinely bilinear in the momenta. The infinite number of Dirac observables can
be expressed in compact and explicit form in terms of the original phase space
variables. They turn out, as expected, to be non-local and form naturally a set
of countable cardinality.Comment: 32p, LATE
Soluble Host Defense Lectins in Innate Immunity to Influenza Virus
Host defenses against viral infections depend on a complex interplay of innate (nonspecific) and adaptive (specific) components. In the early stages of infection, innate mechanisms represent the main line of host defense, acting to limit the spread of virus in host tissues prior to the induction of the adaptive immune response. Serum and lung fluids contain a range of lectins capable of recognizing and destroying influenza A viruses (IAV). Herein, we review the mechanisms by which soluble endogenous lectins mediate anti-IAV activity, including their role in modulating IAV-induced inflammation and disease and their potential as prophylactic and/or therapeutic treatments during severe IAV-induced disease
Celebrity, Death, and Taxes: Michael Jackson\u27s Estate
The untimely death of Michael Jackson this past June presents an opportunity to reassess certain thorny estate tax issues that may arise when a celebrity dies owning valuable intellectual property. Elsewhere we have debated hypothetical, tax-motivated changes to state laws relating to postmortem publicity rights. This article focuses on existing legislation, like California’s, that makes publicity rights both devisable and descendible. Federal transfer taxes are levied on intangible property as well as tangible assets, and therefore apply to intellectual property, including a celebrity’s right of publicity and copyrights retained by an artist in his or her creations. Using Michael Jackson’s estate as an example, and focusing primarily on publicity rights, we examine two questions that any estate planner representing a celebrity client ought to consider. First, how should a personal representative value intellectual property for estate tax purposes? Second, what strategies are available to lessen the estate tax burden associated with certain intellectual property rights
Pressure Induced Hydration Dynamics of Membranes
Pressure-jump initiated time-resolved x-ray diffraction studies of dynamics
of the hydration of the hexagonal phase in biological membranes show that (i)
the relaxation of the unit cell spacing is non-exponential in time; (ii) the
Bragg peaks shift smoothly to their final positions without significant
broadening or loss in crystalline order. This suggests that the hydration is
not diffusion limited but occurs via a rather homogeneous swelling of the whole
lattice, described by power law kinetics with an exponent .Comment: REVTEX 3, 10 pages,3 figures(available on request),#
Arithmetic Spacetime Geometry from String Theory
An arithmetic framework to string compactification is described. The approach
is exemplified by formulating a strategy that allows to construct geometric
compactifications from exactly solvable theories at . It is shown that the
conformal field theoretic characters can be derived from the geometry of
spacetime, and that the geometry is uniquely determined by the two-dimensional
field theory on the world sheet. The modular forms that appear in these
constructions admit complex multiplication, and allow an interpretation as
generalized McKay-Thompson series associated to the Mathieu and Conway groups.
This leads to a string motivated notion of arithmetic moonshine.Comment: 36 page
Conformal blocks and generalized theta functions
Let M(r) be the moduli space of rank r vector bundles with trivial
determinant on a Riemann surface X . This space carries a natural line bundle,
the determinant line bundle L . We describe a canonical isomorphism of the
space of global sections of L^k with a space known in conformal field theory as
the ``space of conformal blocks", which is defined in terms of representations
of the Lie algebra sl(r, C((z))).Comment: 43 pages, Plain Te
Radiative lifetime measurements of rubidium Rydberg states
We have measured the radiative lifetimes of ns, np and nd Rydberg states of
rubidium in the range 28 < n < 45. To enable long-lived states to be measured,
our experiment uses slow-moving Rb atoms in a magneto-optical trap (MOT). Two
experimental techniques have been adopted to reduce random and systematic
errors. First, a narrow-bandwidth pulsed laser is used to excite the target
Rydberg state, resulting in minimal shot-to-shot variation in the initial state
population. Second, we monitor the target state population as a function of
time delay from the laser pulse using a short-duration, millimetre-wave pulse
that is resonant with a one- or two-photon transition. We then selectively
field ionize the monitor state, and detect the resulting electrons with a
micro-channel plate. This signal is an accurate mirror of the target state
population, and is uncontaminated by contributions from other states which are
populated by black body radiation. Our results are generally consistent with
other recent experimental results obtained using a less sensitive method, and
are also in excellent agreement with theory.Comment: 27 pages,6 figure
Loss of a single N-linked glycan from the hemagglutinin of influenza virus is associated with resistance to collectins and increased virulence in mice
BACKGROUND: Glycosylation on the globular head of the hemagglutinin (HA) protein of influenza virus acts as an important target for recognition and destruction of virus by innate immune proteins of the collectin family. This, in turn, modulates the virulence of different viruses for mice. The role of particular oligosaccharide attachments on the HA in determining sensitivity to collectins has yet to be fully elucidated. METHODS: When comparing the virulence of H3N2 subtype viruses for mice we found that viruses isolated after 1980 were highly glycosylated and induced mild disease in mice. During these studies, we were surprised to find a small plaque variant of strain A/Beijing/353/89 (Beij/89) emerged following infection of mice and grew to high titres in mouse lung. In the current study we have characterized the properties of this small plaque mutant both in vitro and in vivo. RESULTS: Small plaque mutants were recovered following plaquing of lung homogenates from mice infected with influenza virus seed Beij/89. Compared to wild-type virus, small plaque mutants showed increased virulence in mice yet did not differ in their ability to infect or replicate in airway epithelial cells in vitro. Instead, small plaque variants were markedly resistant to neutralization by murine collectins, a property that correlated with the acquisition of an amino acid substitution at residue 246 on the viral HA. We present evidence that this substitution was associated with the loss of an oligosaccharide glycan from the globular head of HA. CONCLUSION: A point mutation in the gene encoding the HA of Beij/89 was shown to ablate a glycan attachment site. This was associated with resistance to collectins and increased virulence in mice
The Anatomy of Memory Politics: A Formalist Analysis of Tate Britain’s ‘Artist and Empire’ and the Struggle over Britain’s Imperial Past
In this paper, I propose a new approach for understanding the meaning of memory politics, which draws upon the archetypal literary criticism of Northrop Frye. I suggest that the four archetypes elaborated by Frye—comedy, romance, tragedy, and satire—can be used as a heuristic device for interpreting the contested historical narratives that are associated with the politics of memory. I illustrate this approach through a case-study of Artists and Empire: Facing Britain’s Imperial Past, an exhibition held at Tate Britain in 2016, amidst increasing contestation over the meaning of the British Empire. In sum, I find that the exhibit narrated Britain’s imperial past as a comedy, in which a key theme was the progressive cultural mixing of the British and the people they colonized. To conclude, I discuss the implications of such a narrative for constructing an inclusive, postcolonial British identity. As an alternative, I draw on Aristotle to suggest that a tragic narrative would have been more propitious
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