3,244 research outputs found
Alexander representation of tangles
A tangle is an oriented 1-submanifold of the cylinder whose endpoints lie on
the two disks in the boundary of the cylinder. Using an algebraic tool
developed by Lescop, we extend the Burau representation of braids to a functor
from the category of oriented tangles to the category of Z[t,t^{-1}]-modules.
For (1,1)-tangles (i.e., tangles with one endpoint on each disk) this invariant
coincides with the Alexander polynomial of the link obtained by taking the
closure of the tangle. We use the notion of plat position of a tangle to give a
constructive proof of invariance in this case.Comment: 13 pages, 5 figure
Coupled waveguide modes in hexagonal photonic crystals
We investigate the modes of coupled waveguides in a hexagonal photonic crystal. We find that for a substantial parameter range the coupled waveguide modes have dispersion relations exhibiting multiple intersections, which we explain both intuitively and using a rigorous tight-binding argument. © 2010 Optical Society of America
Molecular Theory of Hydrophobic Effects: ``She is too mean to have her name repeated.''
This paper reviews the molecular theory of hydrophobic effects relevant to
biomolecular structure and assembly in aqueous solution. Recent progress has
resulted in simple, validated molecular statistical thermodynamic theories and
clarification of confusing theories of decades ago. Current work is resolving
effects of wider variations of thermodynamic state, e.g. pressure denaturation
of soluble proteins, and more exotic questions such as effects of surface
chemistry in treating stability of macromolecular structures in aqueous
solutionComment: submitted to Ann. Rev. Phys. Chem., 31 pages, 245 references, 2
figure
Coupled photonic crystal waveguides in hexagonal lattices
We investigate the dispersion curves of coupled waveguides in hexagonal lattices. We show that hexagonal PCW lattices have coupling coefficients that change magnitude and sign along the BZ. It is also shown that the modes of these structures no longer form odd and even modes but are superposed in a more general sense. © 2010 OSA /FiO/LS 2010
Longitudinal study of the effect of sporidesmin toxicity on lamb production and serum biochemistry in a flock of 46 Romney ewes using a standardised measure of liver damage
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In vitro susceptibility of recent Chlamydia trachomatis clinical isolates to the CtHtrA inhibitor JO146
© 2015 Institut Pasteur. The present study aimed to establish if a previously identified Chlamydia trachomatis HtrA (CtHtrA) inhibitor, JO146, is effective against currently circulating clinical isolates to validate if CtHtrA is a clinically relevant target for future therapeutic development. Inhibition of CtHtrA during the middle of the chlamydial replicative cycle until the completion of the cycle resulted in loss of infectious progeny for six unique clinical isolates representing different serovars. This supports the potential for CtHtrA to be a clinically relevant target for development of new therapeutics and suggests the importance of further investigation of JO146 as a lead compound
Invasive aspergillosis complicating treatment with tyrosine kinase inhibitors
We describe three cases of pulmonary aspergillosis (PA) in three patients without traditional risk factors
for invasive aspergillosis infection, such as prolonged neutropenia or high dose systemic corticosteroid
therapy. All three patients developed PA whilst taking tyrosine kinase inhibitors (TKI) and sustained
greater clinical improvement once TKI were withdrawn. Our case series supports the theory TKI
treatment can increase susceptibility to PA without causing neutropenia. Recognition that TKI treatment
may predispose to invasive aspergillosis will allow for rapid recognition of patients of affected patients
and more effective management of future cases
A direct image of the obscuring disk surrounding an active galactic nucleus
Active galactic nuclei (AGN) are generally accepted to be powered by the
release of gravitational energy in a compact accretion disk surrounding a
massive black hole. Such disks are also necessary to collimate powerful radio
jets seen in some AGN. The unifying classification schemes for AGN further
propose that differences in their appearance can be attributed to the opacity
of the accreting material, which may obstruct our view of the central region of
some systems. The popular model for the obscuring medium is a parsec-scale disk
of dense molecular gas, although evidence for such disks has been mostly
indirect, as their angular size is much smaller than the resolution of
conventional telescopes. Here we report the first direct images of a pc-scale
disk of ionised gas within the nucleus of NGC 1068, the archetype of obscured
AGN. The disk is viewed nearly edge-on, and individual clouds within the
ionised disk are opaque to high-energy radiation, consistent with the unifying
classification scheme. In projection, the disk and AGN axes align, from which
we infer that the ionised gas disk traces the outer regions of the long-sought
inner accretion disk.Comment: 14 pages, LaTeX, PSfig, to appear in Nature. also available at
http://hethp.mpe-garching.mpg.de/Preprint
On Semiclassical Limits of String States
We explore the relation between classical and quantum states in both open and
closed (super)strings discussing the relevance of coherent states as a
semiclassical approximation. For the closed string sector a gauge-fixing of the
residual world-sheet rigid translation symmetry of the light-cone gauge is
needed for the construction to be possible. The circular target-space loop
example is worked out explicitly.Comment: 12 page
The prevalence of axial spondyloarthritis in the UK: a cross-sectional cohort study
Background: Accurate prevalence data are important when interpreting diagnostic tests and planning for the health needs of a population, yet no such data exist for axial spondyloarthritis (axSpA) in the UK. In this cross-sectional cohort study we aimed to estimate the prevalence of axSpA in a UK primary care population. Methods: A validated self-completed questionnaire was used to screen primary care patients with low back pain for inflammatory back pain (IBP). Patients with a verifiable pre-existing diagnosis of axSpA were included as positive cases. All other patients meeting the Assessment of SpondyloArthritis international Society (ASAS) IBP criteria were invited to undergo further assessment including MRI scanning, allowing classification according to the European Spondyloarthropathy Study Group (ESSG) and ASAS axSpA criteria, and the modified New York (mNY) criteria for ankylosing spondylitis (AS). Results: Of 978 questionnaires sent to potential participants 505 were returned (response rate 51.6 %). Six subjects had a prior diagnosis of axSpA, 4 of whom met mNY criteria. Thirty eight of 75 subjects meeting ASAS IBP criteria attended review (mean age 53.5 years, 37 % male). The number of subjects satisfying classification criteria was 23 for ESSG, 3 for ASAS (2 clinical, 1 radiological) and 1 for mNY criteria. This equates to a prevalence of 5.3 % (95 % CI 4.0, 6.8) using ESSG, 1.3 % (95 % CI 0.8, 2.3) using ASAS, 0.66 % (95 % CI 0.28, 1.3) using mNY criteria in chronic back pain patients, and 1.2 % (95 % CI 0.9, 1.4) using ESSG, 0.3 % (95 % CI 0.13, 0.48) using ASAS, 0.15 % (95 % CI 0.02, 0.27) using mNY criteria in the general adult primary care population. Conclusions: These are the first prevalence estimates for axSpA in the UK, and will be of importance in planning for the future healthcare needs of this population. Trial registration: Current Controlled Trials ISRCTN7687321
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