2,456 research outputs found
Texture Synthesis Through Convolutional Neural Networks and Spectrum Constraints
This paper presents a significant improvement for the synthesis of texture
images using convolutional neural networks (CNNs), making use of constraints on
the Fourier spectrum of the results. More precisely, the texture synthesis is
regarded as a constrained optimization problem, with constraints conditioning
both the Fourier spectrum and statistical features learned by CNNs. In contrast
with existing methods, the presented method inherits from previous CNN
approaches the ability to depict local structures and fine scale details, and
at the same time yields coherent large scale structures, even in the case of
quasi-periodic images. This is done at no extra computational cost. Synthesis
experiments on various images show a clear improvement compared to a recent
state-of-the art method relying on CNN constraints only
Validity of single-channel model for a spin-orbit coupled atomic Fermi gas near Feshbach resonances
We theoretically investigate a Rashba spin-orbit coupled Fermi gas near
Feshbach resonances, by using mean-field theory and a two-channel model that
takes into account explicitly Feshbach molecules in the close channel. In the
absence of spin-orbit coupling, when the channel coupling between the
closed and open channels is strong, it is widely accepted that the two-channel
model is equivalent to a single-channel model that excludes Feshbach molecules.
This is the so-called broad resonance limit, which is well-satisfied by
ultracold atomic Fermi gases of Li atoms and K atoms in current
experiments. Here, with Rashba spin-orbit coupling we find that the condition
for equivalence becomes much more stringent. As a result, the single-channel
model may already be insufficient to describe properly an atomic Fermi gas of
K atoms at a moderate spin-orbit coupling. We determine a characteristic
channel coupling strength as a function of the spin-orbit coupling
strength, above which the single-channel and two-channel models are
approximately equivalent. We also find that for narrow resonance with small
channel coupling, the pairing gap and molecular fraction is strongly suppressed
by SO coupling. Our results can be readily tested in K atoms by using
optical molecular spectroscopy.Comment: 6 pages, 6 figure
Superfluid density and Berezinskii-Kosterlitz-Thouless transition of a spin-orbit coupled Fulde-Ferrell superfluid
We theoretically investigate the superfluid density and
Berezinskii-Kosterlitz-Thouless (BKT) transition of a two-dimensional Rashba
spin-orbit coupled atomic Fermi gas with both in-plane and out-of-plane Zeeman
fields. It was recently predicted that, by tuning the two Zeeman fields, the
system may exhibit different exotic Fulde-Ferrell (FF) superfluid phases,
including the gapped FF, gapless FF, gapless topological FF and gapped
topological FF states. Due to the FF paring, we show that the superfluid
density (tensor) of the system becomes anisotropic. When an in-plane Zeeman
field is applied along the \textit{x}-direction, the tensor component along the
\textit{y}-direction is generally larger than in most
parameter space. At zero temperature, there is always a discontinuity jump in
as the system evolves from a gapped FF into a gapless FF state. With
increasing temperature, such a jump is gradually washed out. The critical BKT
temperature has been calculated as functions of the spin-orbit coupling
strength, interatomic interaction strength, in-plane and out-of-plane Zeeman
fields. We predict that the novel FF superfluid phases have a significant
critical BKT temperature, typically at the order of , where
is the Fermi degenerate temperature. Therefore, their observation is within the
reach of current experimental techniques in cold-atom laboratories.Comment: 11 pages, 7 figure
Gapless topological Fulde-Ferrell superfluidity in spin-orbit coupled Fermi gases
Topological superfluids usually refer to a superfluid state which is gapped
in the bulk but metallic at the boundary. Here we report that a gapless,
topologically non-trivial superfluid with inhomogeneous Fulde-Ferrell pairing
order parameter can emerge in a two-dimensional spin-orbit coupled Fermi gas,
in the presence of both in-plane and out-of-plane Zeeman fields. The
Fulde-Ferrell pairing - induced by the spin-orbit coupling and in-plane Zeeman
field - is responsible for this gapless feature. This exotic superfluid has a
significant Berezinskii-Kosterlitz-Thouless (BKT) transition temperature and
has robust Majorana edge modes against disorder owing to its topological
nature.Comment: 5 pages, 5 figures; add the results on the critical BKT temperature
and superfluid density, as well as the discussion on the robustness of the
chiral edge states against disorde
Effect of a poloxamer 407-based thermosensitive gel on minimization of thermal injury to diaphragm during microwave ablation of the liver.
AIM: To assess the insulating effect of a poloxamer 407 (P407)-based gel during microwave ablation of liver adjacent to the diaphragm.
METHODS: We prepared serial dilutions of P407, and 22.5% (w/w) concentration was identified as suitable for ablation procedures. Subsequently, microwave ablations were performed on the livers of 24 rabbits (gel, saline, control groups, n = 8 in each). The P407 solution and 0.9% normal saline were injected into the potential space between the diaphragm and liver in experimental groups. No barriers were applied to the controls. After microwave ablations, the frequency, size and degree of thermal injury were compared histologically among the three groups. Subsequently, another 8 rabbits were injected with the P407 solution and microwave ablation was performed. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN) and creatinine (Cr) in serum were tested at 1 d before microwave ablation and 3 and 7 d after operation.
RESULTS: In vivo ablation thermal injury to the adjacent diaphragm was evaluated in the control, saline and 22.5% P407 gel groups (P = 0.001-0.040). However, there was no significant difference in the volume of ablation zone among the three groups (P \u3e 0.05). Moreover, there were no statistical differences among the preoperative and postoperative gel groups according to the levels of ALT, AST, BUN and Cr in serum (all P \u3e 0.05).
CONCLUSION: Twenty-two point five percent P407 gel could be a more effective choice during microwave ablation of hepatic tumors adjacent to the diaphragm. Further studies for clinical translation are warranted
Axial Force Analysis and Roll Contour Configuration of Four-High CVC Mill
In order to analyze the influence of technical parameters on work roll axial force of four-high continuous variable crown (CVC) mill, the deformation analyzing model with top roll system and strip was established based on influence function method. Then a CVC work roll curve designing scheme was proposed and it was carried out on some cold rolling mill considering the requirement of comprehensive work roll axial force minimization. The status of comprehensive work roll axial force is improved considering the rolling schedule that is beneficial to the roller bearing. Corresponding to the newly designed work roll contour, the backup roll end chamfer was designed considering comprehensive performance of interroll stress concentration, comprehensive work roll axial force, and strip shape control ability. The distribution of roll wear with newly designed backup roll contour is more even according to the field application data. The newly established roll configuration scheme is beneficial to four-high CVC mill
Diethyl [hydroxy(phenyl)methyl]phosphonate
Molecules of the title compound, C11H17O4P, are linked into chiral helical chains along the crystallographic b axis via O—H⋯O hydrogen bonds between the hydroxy group and an O atom of the phosphonate group. One ethyl group is disordered over two positions; the site occupancy factors are ca 0.7 and 0.3
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