666 research outputs found
Asymptotics and Dimensional Dependence of the Number of Critical Points of Random Holomorphic Sections
We prove two conjectures from [M. R. Douglas, B. Shiffman and S. Zelditch,
Critical points and supersymmetric vacua, II: Asymptotics and extremal metrics.
J. Differential Geom. 72 (2006), no. 3, 381-427] concerning the expected number
of critical points of random holomorphic sections of a positive line bundle. We
show that, on average, the critical points of minimal Morse index are the most
plentiful for holomorphic sections of {\mathcal O}(N) \to \CP^m and, in an
asymptotic sense, for those of line bundles over general K\"ahler manifolds. We
calculate the expected number of these critical points for the respective cases
and use these to obtain growth rates and asymptotic bounds for the total
expected number of critical points in these cases. This line of research was
motivated by landscape problems in string theory and spin glasses.Comment: 14 pages, corrected typo
The future for global water assessment
The global water cycle is a fundamental component of our climate and Earth system. Many, if not the
majority, of the impacts of climate change are water related. We have an imperfect description and
understanding of components of the water cycle. This arises from an incomplete observation of some
of the stores and fluxes in the water cycle (in particular: precipitation, evaporation, soil moisture and
groundwater), problems with the simulation of precipitation by global climate models and the wide
diversity of global hydrological models currently in use. This paper discusses these sources of errors
and, in particular, explores the errors and advantages of bias correcting climate model outputs for hydrological
models using a single large catchment as an example (the Rhine). One conclusion from this analysis
is that bias correction is necessary and has an impact on the mean flows and their seasonal cycle.
However choice of hydrological model has an equal, if not larger effect on the quality of the simulation.
The paper highlights the importance of improving hydrological models, which run at a continental and
global scale, and the importance of quantifying uncertainties in impact studies
Real-time PCR based on SYBR-Green I fluorescence: An alternative to the TaqMan assay for a relative quantification of gene rearrangements, gene amplifications and micro gene deletions
BACKGROUND:
Real-time PCR is increasingly being adopted for RNA quantification and genetic analysis. At present the most popular real-time PCR assay is based on the hybridisation of a dual-labelled probe to the PCR product, and the development of a signal by loss of fluorescence quenching as PCR degrades the probe. Though this so-called 'TaqMan' approach has proved easy to optimise in practice, the dual-labelled probes are relatively expensive.
RESULTS:
We have designed a new assay based on SYBR-Green I binding that is quick, reliable, easily optimised and compares well with the published assay. Here we demonstrate its general applicability by measuring copy number in three different genetic contexts; the quantification of a gene rearrangement (T-cell receptor excision circles (TREC) in peripheral blood mononuclear cells); the detection and quantification of GLI, MYC-C and MYC-N gene amplification in cell lines and cancer biopsies; and detection of deletions in the OPA1 gene in dominant optic atrophy.
CONCLUSION:
Our assay has important clinical applications, providing accurate diagnostic results in less time, from less biopsy material and at less cost than assays currently employed such as FISH or Southern blotting
Giant Alcohol: A Worthy Opponent for the Children of the Band of Hope
From its foundation in 1847, the temperance organisation the Band of Hope addressed its young members as consumers, victims, and agents. In the first two roles they encountered the effects of drink of necessity, but in the third role they were encouraged to seek it out, attempting to influence individuals and wider society against 'Giant Alcohol'.
With an estimated membership of half the school-age population by the early twentieth century, well over three million, the Band of Hope also acted more directly to influence policy, and encouraged young people to consider issues of policy and politics. With its wide range of activities and material to educate, entertain and empower millions of children, and its radical view of the place of the child, the Band of Hope not only mobilised its child members to lobby for legal change, including prohibition, but took an active part in pointing out the cost of alcohol to society, particularly during the 14-18 war. The organisation began to decline post 1918, and this paper focuses on the address made to children by the Band of Hope in the late nineteenth and early twentieth centuries, at a time when its innovative view of children as able to understand and influence policy decisions reflected developments in the construction of childhood. This article draws on the archive of the British National Temperance League, over 50,000 items located in the Livesey Collection, University of Central Lancashire
entropy of M5 branes from dielectric effect
We observe that the entropy behavior of near-extermal M5 branes can be
reproduced from SYM side with the role of Myers' terms. We start by
generalizing the Klebanov-Tseytlin (KT) supergravity solution that displays the
entropy behavior. The new feature of the general solution is visibility
of the "internal" degrees of the M5 branes, i.e., the M0 branes and the M2
branes. With the rationale provided by the supergravity analysis, we consider a
D0 brane quantum mechanical setup with Myers' terms. Using localization
technique, we show that the leading behavior of the free energy comes
from the "classical contribution" with the rest sub-leading.Comment: latex, 21 pages, missing figure adde
Constrained Dynamics of an Anomalous Relativistic Spinning Particle in Electromagnetic Background
In this paper we have considered the dynamics of an anomalous ()
charged relativistic spinning particle in the presence of an external
electromagnetic field. The constraint analysis is done and the complete set of
Dirac brackets are provided that generate the canonical Lorentz algebra and
dynamics through Hamiltonian equations of motion. The spin-induced effective
curvature of spacetime and its possible connection with Analogue Gravity models
are commented upon.Comment: 10 pages Latex, minor corrections and changes in ref., slightly
enlarged version, to appear in EPJ
The Three-Dimensional Noncommutative Nonlinear Sigma Model in Superspace
We study the superspace formulation of the noncommutative nonlinear
supersymmetric O(N) invariant sigma-model in 2+1 dimensions. We prove that the
model is renormalizable to all orders of 1/N and explicitly verify that the
model is asymptotically free.Comment: 16 pages, 5 figures, Revte
Inhomogeneous chiral symmetry breaking in noncommutative four fermion interactions
The generalization of the Gross-Neveu model for noncommutative 3+1 space-time
has been analyzed. We find indications that the chiral symmetry breaking occurs
for an inhomogeneous background as in the LOFF phase in condensed matter.Comment: 17 pages, 2 figures, published version, minor correction
The outer halos of elliptical galaxies
Recent progress is summarized on the determination of the density
distributions of stars and dark matter, stellar kinematics, and stellar
population properties, in the extended, low surface brightness halo regions of
elliptical galaxies. With integral field absorption spectroscopy and with
planetary nebulae as tracers, velocity dispersion and rotation profiles have
been followed to ~4 and ~5-8 effective radii, respectively, and in M87 to the
outer edge at ~150 kpc. The results are generally consistent with the known
dichotomy of elliptical galaxy types, but some galaxies show more complex
rotation profiles in their halos and there is a higher incidence of
misalignments, indicating triaxiality. Dynamical models have shown a range of
slopes for the total mass profiles, and that the inner dark matter densities in
ellipticals are higher than in spiral galaxies, indicating earlier assembly
redshifts. Analysis of the hot X-ray emitting gas in X-ray bright ellipticals
and comparison with dynamical mass determinations indicates that non-thermal
components to the pressure may be important in the inner ~10 kpc, and that the
properties of these systems are closely related to their group environments.
First results on the outer halo stellar population properties do not yet give a
clear picture. In the halo of one bright galaxy, lower [alpha/Fe] abundances
indicate longer star formation histories pointing towards late accretion of the
halo. This is consistent with independent evidence for on-going accretion, and
suggests a connection to the observed size evolution of elliptical galaxies
with redshift.Comment: 8 pages. Invited review to appear in the proceedings of "Galaxies and
their Masks" eds. Block, D.L., Freeman, K.C. & Puerari, I., 2010, Springer
(New York
An Atom Probe Tomography study of site preference and partitioning in a nickel-based superalloy
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