17,740 research outputs found
Nongauge bright soliton of the nonlinear Schrodinger (NLS) equation and a family of generalized NLS equations
We present an approach to the bright soliton solution of the NLS equation
from the standpoint of introducing a constant potential term in the equation.
We discuss a `nongauge' bright soliton for which both the envelope and the
phase depend only on the traveling variable. We also construct a family of
generalized NLS equations with solitonic sech^p solutions in the traveling
variable and find an exact equivalence with other nonlinear equations, such as
the Korteveg-de Vries and Benjamin-Bona-Mahony equations when p=2Comment: ~4 pages, 3 figures, 16 references, published versio
Parallel ion strings in linear multipole traps
Additional radio-frequency (rf) potentials applied to linear multipole traps
create extra field nodes in the radial plane which allow one to confine single
ions, or strings of ions, in totally rf field-free regions. The number of nodes
depends on the order of the applied multipole potentials and their relative
distance can be easily tuned by the amplitude variation of the applied
voltages. Simulations using molecular dynamics show that strings of ions can be
laser cooled down to the Doppler limit in all directions of space. Once cooled,
organized systems can be moved with very limited heating, even if the cooling
process is turned off
Communications Biophysics
Contains reports on two research projects.United States Air Force (Contract AF19(604)-4112
An Inversion Disrupting FAM134B Is Associated with Sensory Neuropathy in the Border Collie Dog Breed
Sensory neuropathy in the Border Collie is a severe neurological disorder caused by the degeneration of sensory and, to a lesser extent, motor nerve cells with clinical signs starting between 2 and 7 months of age. Using a genome-wide association study approach with three cases and 170 breed matched controls, a suggestive locus for sensory neuropathy was identified that was followed up using a genome sequencing approach. An inversion disrupting the candidate gene FAM134B was identified. Genotyping of additional cases and controls and RNAseq analysis provided strong evidence that the inversion is causal. Evidence of cryptic splicing resulting in novel exon transcription for FAM134B was identified by RNAseq experiments. This investigation demonstrates the identification of a novel sensory neuropathy associated mutation, by mapping using a minimal set of cases and subsequent genome sequencing. Through mutation screening, it should be possible to reduce the frequency of or completely eliminate this debilitating condition from the Border Collie breed population
Studies of CMB structure at Dec=40. II: Analysis and cosmological interpretation
We present a detailed analysis of the cosmic microwave background structure
in the Tenerife Dec=+40 degrees data. The effect of local atmospheric
contributions on the derived fluctuation amplitude is considered, resulting in
an improved separation of the intrinsic CMB signal from noise. Our analysis
demonstrates the existence of common structure in independent data scans at 15
and 33 GHz. For the case of fluctuations described by a Gaussian
auto-correlation function, a likelihood analysis of our combined results at 15
and 33 GHz implies an intrinsic rms fluctuation level of 48^{+21}_{-15} uK on a
coherence scale of 4 degrees; the equivalent analysis for a
Harrison-Zel'dovitch model gives a power spectrum normalisation of Q_{rms-ps} =
22^{+10}_{-6} uK. The fluctuation amplitude is seen to be consistent at the 68%
confidence level with that reported for the COBE two-year data for primordial
fluctuations described by a power law model with a spectral index in the range
1.0 \le n \le 1.6. This limit favours the large scale CMB anisotropy being
dominated by scalar fluctuations rather than tensor modes from a gravitational
wave background. The large scale Tenerife and COBE results are considered in
conjunction with observational results from medium scale experiments in order
to place improved limits on the fluctuation spectral index; we find n=1.10 +/-
0.10 assuming standard CDM with H_{0}=50 kms^{-1}Mpc^{-1}.Comment: 10 pages LaTeX, including 8 PostScript figures. Accepted for
publication in MNRA
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