49,191 research outputs found
Spin 1 inversion: a Majorana tensor force for deuteron alpha scattering
We demonstrate, for the first time, successful S-matrix to potential
inversion for spin one projectiles with non-diagonal yielding a
interaction. The method is a generalization of the
iterative-perturbative, IP, method. We present a test case indicating the
degree of uniqueness of the potential. The method is adapted, using established
procedures, into direct observable to potential inversion, fitting ,
, , and for d + alpha scattering over
a range of energies near 10 MeV. The interaction which we find is
very different from that proposed elsewhere, both real and imaginary parts
being very different for odd and even parity channels.Comment: 7 pages Revtex, 4 ps figure
Dynamics of broken symmetry lambda phi^4 field theory
We study the domain of validity of a Schwinger-Dyson (SD) approach to
non-equilibrium dynamics when there is broken symmetry. We perform exact
numerical simulations of the one- and two-point functions of lambda phi^4 field
theory in 1+1 dimensions in the classical domain for initial conditions where <
phi(x) > not equal to 0. We compare these results to two self-consistent
truncations of the SD equations which ignore three-point vertex function
corrections. The first approximation, which sets the three-point function to
one (the bare vertex approximation (BVA)) gives an excellent description for <
phi(x) > = phi(t). The second approximation which ignores higher in 1/N
corrections to the 2-PI generating functional (2PI -1/N expansion) is not as
accurate for phi(t). Both approximations have serious deficiencies in
describing the two-point function when phi(0) > .4.Comment: 10 pages, 6 figure
Coordination and synergism between visual and vocal display in the brown-headed cowbirds
Journal ArticleSexually selected acoustic signaling is accompanied by visual displays in many birds. The motor integration of visual and vocal displays has not been extensively studied. Brown-headed cowbirds (Molothrus ater) "puff up" prior to song, move their wings during the song and conclude with a bow. The Society for Neuroscience 33rd Annual Meeting Selected Abstracts Coordination and synergism between visual and vocal display in brown - headed cowbirds. B. G. Cooper; F. Goller Dept. Biol, Univ. Utah, Salt Lake City, UT, USA Program Number: 294.13 Presentation Time: Sunday, Nov. 9, 1: 00 PM - 2: 00 P
Respiratory motor correlates of song plasticity in young adult zebra finches
Journal ArticleYoung adult zebra finches (Taeniopygia guttata, 90150 phd) sing a stereotyped song, but can show rapid changes in song structure if sensory feedback is disrupted. The vocal motor correlates accompanying induced song plasticity have not yet been examined. To investigate motor changes underlying song plasticity, air sac pressure and vocal output were recorded in zebra finches (N=4, 90-120 phd) prior to, during, and after removal (reversal) of a clamp placed in each bronchus. The clamp restricted movement of the lateral labia and reduced, or completely eliminated, sound production during song
Study of a signal processor employing a synthetic phase isolator
Evaluation of signal data processor employing synthetic phase isolator techniqu
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Exploring mutualistic interactions between microalgae and bacteria in the omics age.
Microalgae undertake a wide range of mutualistic interactions with bacteria. Here we consider how transcriptomic, metagenomic and metabolomic approaches have been combined with microbiological and biochemical analyses to expand our understanding of algal-bacterial interactions. Identification of the major bacterial species associated with algae indicates that specific bacterial groups, particularly the alpha-Proteobacteria, are found more frequently, suggesting that these may have the means to initiate and maintain symbiotic relationships. Nutrient exchange is frequently the basis of algal-bacterial mutualism, and as the compounds involved are characterised, evidence is accumulating that these are complex and specific molecules, offering opportunities for signalling processes and regulation rather than merely passive diffusion. At the same time, it is clear that the interactions are not static, but can be initiated and broken in response to environmental and developmental cues.We thank the Biotechnology and Biological Sciences Research Council (BBSRC) of the UK, and PML Applications Ltd., Plymouth UK, for the CASE studentship for MBC.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.pbi.2015.07.00
Exact and approximate dynamics of the quantum mechanical O(N) model
We study a quantum dynamical system of N, O(N) symmetric, nonlinear
oscillators as a toy model to investigate the systematics of a 1/N expansion.
The closed time path (CTP) formalism melded with an expansion in 1/N is used to
derive time evolution equations valid to order 1/N (next-to-leading order). The
effective potential is also obtained to this order and its properties
areelucidated. In order to compare theoretical predictions against numerical
solutions of the time-dependent Schrodinger equation, we consider two initial
conditions consistent with O(N) symmetry, one of them a quantum roll, the other
a wave packet initially to one side of the potential minimum, whose center has
all coordinates equal. For the case of the quantum roll we map out the domain
of validity of the large-N expansion. We discuss unitarity violation in the 1/N
expansion; a well-known problem faced by moment truncation techniques. The 1/N
results, both static and dynamic, are also compared to those given by the
Hartree variational ansatz at given values of N. We conclude that late-time
behavior, where nonlinear effects are significant, is not well-described by
either approximation.Comment: 16 pages, 12 figrures, revte
Twisting moduli for GL(2)
We prove various converse theorems for automorphic forms on \Gamma_0(N), each assuming fewer twisted functional equations than the last. We show that no twisting at all is needed for holomorphic modular forms in the case that N\in{18,20,24} - these integers are the smallest multiples of 4 or 9 not covered by earlier work of Conrey–Farmer. This development is a consequence of finding generating sets for \Gamma_0(N) such that each generator can be written as a product of special matrices. As for real-analytic Maass forms of even (resp. odd) weight we prove the analogous statement for 1\leq N\leq 12, 14\leq N\leq18 and N\in{16,18} (resp. 1\leq N\leq 12, 14\leq N\leq 18 and N\in{20,23,24})
Protein-mediated dethreading of a biotin-functionalised pseudorotaxane
In this article, we describe the synthesis of new biotin-functionalised naphthalene derivatives 3 and 4 and their complexation behaviour with avidin and neutravidin using a range of analytical techniques. We have shown using 2-(4prime or minute-hydroxyazobenzene)benzoic acid displacement and ITC experiments{,} that compounds 3 and 4 have the propensity to form reasonably high-affinity bioconjugates with avidin and neutravidin. We have also demonstrated using 1H NMR{,} UV-vis and fluorescence spectroscopy that the naphthalene moiety of 3 and 4 facilitates the formation of pseudorotaxane-like structures with 1 in water. We have then investigated the ability of avidin and neutravidin to modulate the complexation between 1 and 3 or 4. UV-vis and fluorescence spectroscopy has shown that in both cases the addition of the protein disrupts complexation between the naphthalene moieties of 3 and 4 with 1
Derivative relation for thermopower in the quantum Hall regime
Recently, Tieke et al (to be published in PRL) have observed the relation
S_{yx} = alpha B dS_{xx}/dB for the components of the thermopower tensor in the
quantum Hall regime, where alpha is a constant and B is the magnetic field.
Simon and Halperin (PRL 73, 3278 (1994)) have suggested that an analogous
relation observed for the resistivity tensor R_{xx} = \alpha B dR_{xy}/dB can
be explained with a model of classical transport in an inhomogeneous medium
where the local Hall resistivity is a function of position and the local
dissipative resistivity is a small constant. In the present paper, we show that
this new thermopower relation can be explained with a similar model.Comment: This paper supercedes cond-mat/9705001 which was withdrawn. 4 pages,
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