1,363 research outputs found
Quantum phase transitions in attractive extended Bose-Hubbard Model with three-body constraint
The effect of nearest-neighbor repulsion on the ground-state phase diagrams
of three-body constrained attractive Bose lattice gases is explored
numerically. When the repulsion is turned on, in addition to the uniform Mott
insulating state and two superfluid phases (the atomic and the dimer
superfluids), a dimer checkerboard solid state appears at unit filling, where
boson pairs form a solid with checkerboard structure. We find also that the
first-order transitions between the uniform Mott insulating state and the
atomic superfluid state can be turned into the continuous ones as the repulsion
is increased. Moreover, the stability regions of the dimer superfluid phase can
be extended to modest values of the hopping parameter by tuning the strength of
the repulsion. Our conclusions hence shed light on the search of the dimer
superfluid phase in real ultracold Bose gases in optical lattices.Comment: 4 + epsilon pages, 5 figures. Rewritten to emphasize the effect of
nonzero nearest-neighbor repulsion. Conclusions unchanged. Accepted for
publication in Phys. Rev.
Supersolid phases in the extended boson hubbard model
We present a comprehensive numerical study on the ground state phase diagram
of the two-dimensional hardcore boson extended Hubbard model with nearest
() and next nearest neighbor () repulsions. In addition to the
quantum solid and superfluid phases, we report the existence of striped
supersolid and three-quarter (quarter) filled supersolid at commensurate
density (0.25) due to the interplay of and
interactions. The nature of three-quarter filled supersolid and the associated
quantum solid will be discussed. Quantum phase transition between the two
supersolids of different symmetries is observed and is clearly of first order.Comment: 4 pages, 6 figure
Bronchioloalveolar carcinoma
AbstractBronchioloalveolar carcinoma is a subtype of adenocarcinoma of the lung with a relatively better prognosis. We reviewed the cases of 50 consecutive patients with bronchioloalveolar carcinoma treated during a 10-year period and attempted to analyze factors related to prognosis. During the 10-year study period, the prevalence of bronchioloalveolar carcinoma relative to adenocarcinoma of the lung remained steady. The subjects included 32 male and 18 female patients with mean ages of 64.7 years and 55.1 years, respectively (p = 0.0030). The preoperative radiographic findings included 40 cases of localized and 10 cases of diffuse bronchioloalveolar carcinoma. The clinicopathologic TNM staging included 20 patients with stage I cancer, 4 with stage II cancer, 11 with stage IIIa cancer, 3 with stage IIIb cancer, and 12 with stage IV cancer. Forty patients with clinical stage I, II, or III disease underwent operation (operability 80%). The resectability rate was 90% (36 of 40). Thirty-four procedures were considered as curative. The overall cumulative survival at 5 years was 22.2% (46.4% for stage I). Different TNM stages showed significant differences in survival time (p = 0.0001). The median survival times were 64.6 months for stage I, 48.0 months for stage II, 24.7 months for stage IIIa, 9.0 months for stage IIIb, and 4.5 months for stage IV disease. The median survival time for localized bronchioloalveolar carcinoma was 27.5 months, and the median survival time for diffuse bronchioloalveolar carcinoma was 4.3 months (p = 0.0002). The median survival time for the curative resection group was 30.6 months, and the median survival time for the noncurative resection or nonresection group was 5.8 months (p = 0.0001). On the basis of this study we conclude that (1) the prevalence of bronchioloalveolar carcinoma is quite steady, (2) bronchioloalveolar carcinoma presents at an earlier age in women, (3) bronchioloalveolar carcinoma frequently presents with lymphatic spread or systemic metastasis at diagnosis, (4) most localized bronchioloalveolar carcinomas are resectable and the prognosis with this type is better than that of the diffuse type, and (5) long-term survival correlates closely with initial roentgenographic appearance, TNM stage, and completeness of surgical resection. (J THORAC CARDIOVASC SURG 1995;110:374-81
Enhanced MRI and MRI-Guided Interventional Procedures in Women with Asymptomatic Silicone-Injected Breasts
Asymptomatic women who have received silicone injection for breast
augmentation have a risk of underestimating breast cancer by
palpation, mammography, or breast sonography. Enhanced breast MRI
is sensitive to display certain nonspecific enhanced lesions or
suspicious lesions. Such nonspecific MRI-detected lesions could be
managed by American College Radiology BI-RADS lexicon and
selectively with MRI-guided techniques biopsy to prevent
unnecessary surgery
Search for quantum dimer phases and transitions in a frustrated spin ladder
A two-leg spin-1/2 ladder with diagonal interactions is investigated
numerically. We focus our attention on the possibility of columnar dimer phase,
which was recently predicted based on a reformulated bosonization theory. By
using density matrix renormalization group technique and exact diagonalization
method, we calculate columnar dimer order parameter, spin correlation on a
rung, string order parameters, and scaled excitation gaps. Carefully using
various finite-size scaling techniques, our results show no support for the
existence of columnar dimer phase in the spin ladder under consideration.Comment: 5 pages, 4 figures. To be published in Phys. Rev.
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