19,761 research outputs found
Phase Diagrams of Three-Component Attractive Ultracold Fermions in One-Dimension
We investigate trions, paired states and quantum phase transitions in
one-dimensional SU(3) attractive fermions in external fields by means of the
Bethe ansatz and the dressed energy formalism. Analytical results for the
ground state energy, critical fields and complete phase diagrams are presented
for weak and strong regimes. Numerical solutions of the dressed energy
equations allow us to examine how the different phase boundaries modify by
varying the inter-component coupling throughout the whole attractive regimes.
The pure trionic phase reduces smoothly by decreasing this coupling until the
weak limit is reached. In this weak regime, a pure BCS-paired phase can be
sustained under certain nonlinear Zeeman splittings. Finally we confirm that
the analytic expressions for the physical quantities and resulting phase
diagrams are highly accurate in the weak and strong coupling regimes.Comment: 12 pages, 3 figures, revised version, accepted in New J. Phy
Micellization in the presence of polyelectrolyte
We present a simple model to study micellization of amphiphiles condensed on
a rodlike polyion. Although the mean field theory leads to a first order
micellization transition for sufficiently strong hydrophobic interactions, the
simulations show that no such thermodynamic phase transition exists. Instead,
the correlations between the condensed amphiphiles can result in a structure
formation very similar to micelles.Comment: 8 pages, 7 figure
Optimum pulse shapes for stimulated Raman adiabatic passage
Stimulated Raman adiabatic passage (STIRAP), driven with pulses of optimum
shape and delay has the potential of reaching fidelities high enough to make it
suitable for fault-tolerant quantum information processing. The optimum pulse
shapes are obtained upon reduction of STIRAP to effective two-state systems. We
use the Dykhne-Davis-Pechukas (DDP) method to minimize nonadiabatic transitions
and to maximize the fidelity of STIRAP. This results in a particular relation
between the pulse shapes of the two fields driving the Raman process. The
DDP-optimized version of STIRAP maintains its robustness against variations in
the pulse intensities and durations, the single-photon detuning and possible
losses from the intermediate state.Comment: 8 pages, 6 figures. submitted to Phys. Rev.
An Unusual Case of Tertiary Syphilis Behaving Like Tongue Squamous Cell Carcinoma.
Syphilis may present with a myriad of oral manifestations in the primary, secondary, and tertiary stages, and may be confused with malignancy. Despite a rise in the incidence of syphilis, tertiary syphilis is exceedingly rare. Tertiary syphilis gummas usually affect the hard palate, while tongue involvement is very rare. A 55-year-old male with extensive smoking and alcohol use was referred for malignancy evaluation with an ulcerative mass creating a tongue cleft, and a positron emission tomography scan suggestive for malignancy. Biopsy results demonstrated no carcinoma but histology demonstrated granulomatous inflammation. Further laboratory results demonstrated elevated rapid plasma reagin titers with Treponema pallidum immunoglobulin G antibodies present. The patient was diagnosed with tertiary syphilis, received appropriate antibiotic therapy, and had healing of the tongue with a persistent cleft. Syphilis may mimic many disease processes. As such, it is important to include this disease in the differential of an unusual tongue lesion. An oral lesion may be the first sign of infection
Modelling of hydrological response to climate change in glacierized Central Asian catchments
The arid lowlands of Central Asia are highly dependent on the water supplied by the Tien Shan mountains. Snow and ice storage make large contributions to current runoff, particularly in summer. Two runoff models with different temporal resolutions, HBV-ETH and OEZ, were applied in three glaciated catchments of the Tien Shan mountains. Scenario runs were produced for a climate change caused by the doubling of atmospheric CO2 as predicted by the GISS global circulation model and assuming a 50% reduction of glaciation extent, as well as a complete loss of glaciation. Agreement of the results was best for runs based on 50% glaciation loss, where both models predict an increase in spring and summer runoff compared to current levels. Scenarios for complete loss of glaciation predict an increase in spring runoff levels, followed by lower runoff levels for July and August. Model predictions differ concerning the degree of reduction of late summer runoff. These scenarios are sensitive to model simulation of basin precipitation, as well as to reduction of glaciation extent
Calculation of compressible turbulent boundary layers with pressure gradients and heat transfer
Calculation of compressible turbulent boundary layers with pressure gradients and heat transfe
Tight local approximation results for max-min linear programs
In a bipartite max-min LP, we are given a bipartite graph \myG = (V \cup I
\cup K, E), where each agent is adjacent to exactly one constraint
and exactly one objective . Each agent controls a
variable . For each we have a nonnegative linear constraint on
the variables of adjacent agents. For each we have a nonnegative
linear objective function of the variables of adjacent agents. The task is to
maximise the minimum of the objective functions. We study local algorithms
where each agent must choose based on input within its
constant-radius neighbourhood in \myG. We show that for every
there exists a local algorithm achieving the approximation ratio . We also show that this result is the best possible
-- no local algorithm can achieve the approximation ratio . Here is the maximum degree of a vertex , and
is the maximum degree of a vertex . As a methodological
contribution, we introduce the technique of graph unfolding for the design of
local approximation algorithms.Comment: 16 page
Dynamics of fast pattern formation in porous silicon by laser interference
Patterns are fabricated on 290 nm thick nanostructured porous silicon layers by phase-mask laser interference using single pulses of an excimer laser (193 nm, 20 ns pulse duration). The dynamics of pattern formation is studied by measuring in real time the intensity of the diffraction orders 0 and 1 at 633 nm. The results show that a transient pattern is formed upon melting at intensity maxima sites within a time 1-µs) upon melting induced by homogeneous beam exposure and related to the different scenario for releasing the heat from hot regions. The diffraction efficiency of the pattern is finally controlled by a combination of laser fluence and initial thickness of the nanostructured porous silicon layer and the present results open perspectives on heat release management upon laser exposure as well as have potential for alternative routes for switching applications.Postprint (published version
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