1,530 research outputs found
Induced interaction in a spin-polarized Fermi gas
We study the effect of the induced interaction on the superfluidtransition
temperature of a spin-polarized Fermi gas. In the BCS limit, the polarization
is very small in the superfluid state, and the effect of the induced
interaction is almost the same as in the spin-balanced case. The temperature Tt
and the polarization Pt of the tricritical point are both reduced from
mean-field results by a factor about 2.22. This reduction is also significant
beyond the BCS limit. In the unitary limit, we find (Pt,Tt/TF)=(0.42,0.16), in
comparison with mean-field and experimental results.Comment: 6 pages, 2 figure
Collinear antiferromagnetic state in a two-dimensional Hubbard model at half filling
In a half-filled Hubbard model on a square lattice, the next-nearest-neighbor
hopping causes spin frustration, and the collinear antiferromagnetic (CAF)
state appears as the ground state with suitable parameters. We find that there
is a metal-insulator transition in the CAF state at a critical on-site
repulsion. When the repulsion is small, the CAF state is metallic, and a van
Hove singularity can be close to the Fermi surface, resulting in either a kink
or a discontinuity in the magnetic moment. When the on-site repulsion is large,
the CAF state is a Mott insulator. A first-order transition from the CAF phase
to the antiferromagnetic phase and a second-order phase transition from the CAF
phase to the paramagnetic phase are obtained in the phase diagram at zero
temperature.Comment: 5 pages, 5 figures, two column
The induced interaction in a Fermi gas with a BEC-BCS crossover
We study the effect of the induced interaction on the superfluid transition
temperature of a Fermi gas with a BEC-BCS crossover. The
Gorkov-Melik-Barkhudarov theory about the induced interaction is extended from
the BCS side to the entire crossover, and the pairing fluctuation is treated in
the approach by Nozi\`{e}res and Schmitt-Rink. At unitarity, the induced
interaction reduces the transition temperature by about twenty percent. In the
BCS limit, the transition temperature is reduced by a factor about 2.22, as
found by Gorkov and Melik-Barkhudarov. Our result shows that the effect of the
induced interaction is important both on the BCS side and in the unitary
region.Comment: 11 pages, 3 figures, to be published in PR
Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover
The Ginzburg-Landau theory of a trapped Fermi gas with a BEC-BCS crossover is
derived by the path-integral method. In addition to the standard
Ginzburg-Landau equation, a second equation describing the total atom density
is obtained. These two coupled equations are necessary to describe both
homogeneous and inhomogeneous systems. The Ginzburg-Landau theory is valid near
the transition temperature on both sides of the crossover. In the
weakly-interacting BEC region, it is also accurate at zero temperature where
the Ginzburg-Landau equation can be mapped onto the Gross-Pitaevskii (GP)
equation. The applicability of GP equation at finite temperature is discussed.
On the BEC side, the fluctuation of the order parameter is studied and the
renormalization to the molecule coupling constant is obtained.Comment: 16 pages, 2 figures, to be published in PR
Novel Compact Three-Way Filtering Power Divider Using Net-Type Resonators
In this paper, we present a novel compact three-way power divider with bandpass responses. The proposed power divider utilizes folded net-type resonators to realize dual functions of filtering and power splitting as well as compact size. Equal power ratio with low magnitude imbalance is achieved due to the highly symmetric structure. For demonstration, an experimental three way filtering power divider is implemented. Good filtering and power division characteristics are observed in the measured results of the circuit. The area of the circuits is 14.5 mm x 21.9 mm or 0.16 λg x 0.24 λg, where the λg is the guide wavelength of the center frequency at 2.1 GHz
A New Phase Transition Related to the Black Hole's Topological Charge
The topological charge of AdS black hole is introduced in
Ref.[1,2], where a complete thermodynamic first law is obtained. In this paper,
we investigate a new phase transition related to the topological charge in
Einstein-Maxwell theory. Firstly, we derive the explicit solutions
corresponding to the divergence of specific heat and determine
the phase transition critical point. Secondly, the curve and curve
are investigated and they exhibit an interesting van der Waals system's
behavior. Critical physical quantities are also obtained which are consistent
with those derived from the specific heat analysis. Thirdly, a van der Waals
system's swallow tail behavior is observed when in the
graph. What's more, the analytic phase transition coexistence lines are
obtained by using the Maxwell equal area law and free energy analysis, the
results of which are consistent with each other.Comment: 11 pages, 5 figure
Protocol: Adeno-Associated Virus-Mediated Gene Transfer in Ex Vivo Cultured Embryonic Mammary Gland
Branching morphogenesis of the murine mammary gland starts during late embryogenesis. It is regulated by the signals emanating both from the epithelium and the mesenchyme, yet the molecular mechanisms regulating this process remain poorly understood. We have previously developed a unique whole organ culture technique for embryonic mammary glands, which provides a powerful tool to monitor and manipulate branching morphogenesis ex vivo. Nowadays, RNA sequencing and other transcriptional profiling techniques provide robust methods to identify components of gene regulatory networks driving branching morphogenesis. However, validation of the candidate genes still mainly depends on the use of the transgenic mouse models, especially in mammary gland studies. By comparing different serotypes of recombinant adeno-associated virus (rAAVs), we found out that rAAVs provide sufficient efficiency for gene transfer with different tissue preferences depending on the serotypes of the virus. AAV-2 and AAV-8 preferentially target epithelial and mesenchymal compartments, respectively, while AAV-9 infects both tissues. Here, we describe a protocol for AAV-mediated gene transfer in ex vivo cultured murine embryonic mammary gland facilitating gene function studies on mammary gland branching morphogenesis.Peer reviewe
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