1,474 research outputs found
Antisymmetric solitons and their interactions in strongly dispersion-managed fiber-optic systems
By means of the variational approximation (VA), a system of ordinary
differential equations (ODEs) is derived to describe the propagation of
antisymmetric solitons in a multi-channel (WDM) optical fiber link subject to
strong dispersion management. Results are reported for a prototypical model
including two channels. Using the VA technique, conditions for stable
propagation of the antisymmetric dispersion-managed (ASDM) solitons in one
channel are found, and complete and incomplete collisions between the solitons
belonging to the different channels are investigated. In particular, it is
shown that formation of a bound inter-channel state of two ASDM solitons is
possible under certain conditions (but may be easily avoided). The VA
predictions for the single- and two-channel systems are compared with direct
simulations of the underlying partial differential equations. In most cases,
the agreement is very good, but in some cases (very closely spaced channels)
the collision may destroy the ASDM solitons. The timing-jitter suppression
factor (JSF) for the ASDM soliton in one channel, and the crosstalk timing
jitter induced by collision between the solitons belonging to the different
channels are also estimated analytically. In particular, the JSF for the ASDM
soliton may be much larger than for its fundamental-soliton counterpart in the
same system.Comment: 15 pages, 10 figures, accepted for publication in Optics
Communication
Caña Brava : trabajo y organización social entre los cortadores de caña
1 archivo PDF (182 páginas)Se analiza el proceso de trabajo en el que están involucrados los cortadores de caña y se presentan algunas experiencias de organización de esta fracción del proletariado agrÃcol
Long-range electronic reconstruction to a -dominated Fermi surface below the LaAlO/SrTiO interface
Low dimensionality, broken symmetry and easily-modulated carrier
concentrations provoke novel electronic phase emergence at oxide interfaces.
However, the spatial extent of such reconstructions - i.e. the interfacial
"depth" - remains unclear. Examining LaAlO/SrTiO heterostructures at
previously unexplored carrier densities cm,
we observe a Shubnikov-de Haas effect for small in-plane fields, characteristic
of an anisotropic 3D Fermi surface with preferential orbital
occupancy extending over at least 100~nm perpendicular to the interface.
Quantum oscillations from the 3D Fermi surface of bulk doped SrTiO emerge
simultaneously at higher . We distinguish three areas in doped
perovskite heterostructures: narrow ( nm) 2D interfaces housing
superconductivity and/or other emergent phases, electronically isotropic
regions far ( nm) from the interface and new intermediate zones where
interfacial proximity renormalises the electronic structure relative to the
bulk.Comment: Supplementary material available at Scientific Reports websit
An Ultra-High-Vacuum Rotating Sample Manipulator with Cryogenic Cooling
We report a homebuilt ultra-high-vacuum (UHV) rotating sample manipulator
with cryogenic cooling. The sample holder is thermally anchored to a built-in
cryogenic cold head through flexible copper beryllium strips, permitting
continuous sample rotation. A similar contact mechanism is implemented for the
electrical wiring to the sample holder for thermometry. The apparatus thus
enables continuous sample rotation at regulated cryogenic temperatures in a UHV
environment. We discuss the potential applications of this apparatus for
cryogenic sputtering.Comment: Cryogenics, ultra-high vacuum, sample manipulato
F.A.R.O.G. FORUM, Vol. 5 No. 6
https://digitalcommons.library.umaine.edu/francoamericain_forum/1018/thumbnail.jp
Multi-band Superconductivity in the Chevrel Phases SnMo6S8 and PbMo6S8
Sub-Kelvin scanning tunnelling spectroscopy in the Chevrel Phases SnMo6S8 and
PbMo6S8 reveals two distinct superconducting gaps with Delta_1 = 3 meV, Delta_2
~ 1.0 meV and Delta_1 = 3.1 meV, Delta_2 ~ 1.4 meV respectively. The gap
distribution is strongly anisotropic, with Delta_2 predominantly seen when
scanning across unit-cell steps on the (001) sample surface. The spectra are
well-fitted by an anisotropic two-band BCS s-wave gap function. Our
spectroscopic data are confirmed by electronic heat capacity measurements which
also provide evidence for a twin-gap scenario.Comment: 5 pages, 4 figure
Three-dimensional view of ultrafast dynamics in photoexcited bacteriorhodopsin in the multiphoton regime and biological relevance
How does chemistry scale in complexity to unerringly direct biological functions? Nass Kovacs et al. have shown that bacteriorhodopsin undergoes structural changes tantalizingly similar to the expected pathway even under excessive excitation. Is the protein structure so highly evolved that it directs all deposited energy into the designed function
Congenital Midline Upper Lip Sinuses: 3 Rare Cases
Congenital sinuses of the upper lip are rare congenital malformations. There have been only 40 cases described in the literature. We report 3 cases of congenital midline upper lip sinus in Caucasian children. Two of those lesions were associated with other anomalies (complete cleft palate and hemifacial macrosomia or submucous cleft palate with bifid uvula). The pathophysiology remains unexplained yet. Congenital upper lip sinuses can be considered as possible microforms of cleft-lips. Associated anomalies are frequent and must be sought. The treatment is a full excision of the sinus tract and of the skin around the punctum in order to avoid risks of recurrence
Tegaserod for Female Patients Suffering From IBS With Mixed Bowel Habits or Constipation: A Randomized Controlled Trial
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73726/1/j.1572-0241.2008.01808.x.pd
Detection of subthreshold pulses in neurons with channel noise
Neurons are subject to various kinds of noise. In addition to synaptic noise,
the stochastic opening and closing of ion channels represents an intrinsic
source of noise that affects the signal processing properties of the neuron. In
this paper, we studied the response of a stochastic Hodgkin-Huxley neuron to
transient input subthreshold pulses. It was found that the average response
time decreases but variance increases as the amplitude of channel noise
increases. In the case of single pulse detection, we show that channel noise
enables one neuron to detect the subthreshold signals and an optimal membrane
area (or channel noise intensity) exists for a single neuron to achieve optimal
performance. However, the detection ability of a single neuron is limited by
large errors. Here, we test a simple neuronal network that can enhance the
pulse detecting abilities of neurons and find dozens of neurons can perfectly
detect subthreshold pulses. The phenomenon of intrinsic stochastic resonance is
also found both at the level of single neurons and at the level of networks. At
the network level, the detection ability of networks can be optimized for the
number of neurons comprising the network.Comment: 14 pages, 9 figure
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