Ground state, quasi-hole, a pair of quasihole wavefunctions and instability in bilayer quantum Hall systems

Bilayer quantum Hall system (BLQH) differ from its single layer counterparts (SLQH) by its symmetry breaking ground state and associated neutral gapless mode in the pseudo-spin sector. Due to the gapless mode, qualitatively good groundstate and low energy excited state wavefunctions at any finite distance is still unknown. We investigate this important open problem by the Composite Boson (CB) theory developed by one of the authors to study BLQH systematically. We derive the ground state, quasi-hole and a pair of quasihole wavefunctions from the CB theory and its dual action. We find that the ground state wavefunction differs from the well known $(111)$ wavefunction at any finite $d$. In addition to commonly known multiplicative factors, the quasi-hole and a pair of quasi-holes wavefunctions also contain non-trivial normalization factors multiplying the correct ground state wavefunction. All the distance dependencies in all the wavefunctions are encoded in the spin part of the ground state wavefunction. The instability encoded in the spin part of the groundstate wavefunction leads to the pseudo-spin density wave formation proposed by one of the authors previously. Some subtleties related to the Lowest Landau Level (LLL) projection of the wavefunctions are briefly discussed.Comment: 9 pages, 1 figure, REVTEX, Final version to appear in Phys. Rev.

Lattice structures of Larkin-Ovchinnikov-Fulde - Ferrell (LOFF) state

Starting from the Ginzburg-Landau free energy describing the normal state to Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) state transition, we evaluate the free energy of seven most common lattice structures such as stripe, square, triangular,Simple Cubic (SC), Face centered Cubic (FCC),Body centered Cubic (BCC) and Quasi-crystal (QC). We find that the stripe phase which is the original LO state, is the most stable phase. This result maybe relevant to the detection of LOFF state in some heavy fermion compounds and the pairing lattice structure of fermions with unequal populations in the BCS side of Feshbach resonance in ultra-cold atoms.Comment: 8 pages, 10 figure

Excitonic Superfluid to pseudo-spin density wave transition in bilayer quantum Hall systems

We construct a quantum Ginsburg-Landau theory to study the quantum phase transition from the excitonic superfluid (ESF) to a possible pseudo-spin density wave (PSDW) at some intermediate distances driven by the magneto-roton minimum collapsing at a finite wavevector. We analyze the properties of the PSDW and explicitly show that a square lattice is the favorite lattice. We suggest that correlated hopping of vacancies in the active and passive layers in the PSDW state leads to very large and temperature dependent drag consistent with the experimental data. Comparisons with previous microscopic numerical calculations are made. Further experimental implications are given.Comment: 4+ pages, 2 figures. Final version to appear in Phys. Rev. Let

Development of a sensitive nested-polymerase chain reaction (PCR) assay for the detection of Ustilago scitaminea

A species-specific polymerase chain reaction (PCR) assay was developed for rapid and accurate detection of Ustilago scitaminea, the causal agent of sugarcane smut disease. Based on nucleotide differences in the internal transcribed spacer (ITS) sequences of U. scitaminea, a pair of species-specific primers, SL1 (5`-CAGTGCACGAAAGTACCTGTGG-3`) and SR2 (5`-CTAGGGCGGTGTTCAGAAGCAC-3`) was designed by using a panel of fungal and bacterial species as controls. The primers SL1/SR2 specifically amplified a unique PCR product about 530 bp in length from U. scitaminea strains with a detecting sensitivity at 200 fg of the fungal genomic DNA in a 25 μl reaction solution. To increase sensitivity, a nested-PCR protocol was further established, which used ITS4/ITS5 as the first-round primers followed by the primer pair SL1/SR2. This protocol increased the detection sensitivity by 10,000-fold compared to the PCR method and could detect the fungal DNA as low as 20 ag. The nested-PCR detected U. scitaminea from young sugarcane leaves with no visible smut disease symptoms. The findings from this study provide a sensitive and reliable technique for the early detection of U. scitaminea, which would be useful for sugarcane quarantine and production of germ-free seedcanes.Keywords: Sugarcane, Ustilago scitaminea, nested-polymerase chain reaction (PCR), molecular detectio

Genetic diversity of Ustilago scitaminea Syd. in Southern China revealed by combined ISSR and RAPD analysis

The polymorphism and similarity relationships among 35 mating-type isolates of Ustilago scitaminea collected from Southern China were determined with random amplified polymorphic DNA (RAPD) and inter-simple  sequence repeat (ISSR) analyses. These fungal isolates were collected from 16 sugarcane cultivars including F134 that is resistant to the physiological race 1 but susceptible to the race 2 of U. scitaminea, and N: Co376  that is immune to both races 1 and 2. Unweighted pair group method with arithmetic mean (UPGMA) cluster  analysis revealed that the U. scitaminea isolates could be divided into 2 groups with a coefficient of 0.74. The  first group comprises two isolates collected from the sugarcane cultivar F134, while the remaining 33 isolates were clustered into the second group. The second group was further divided into two subgroups with most of  the isolates from Guangdong Province which clustered in the same subgroup, and all the isolates from Guangxi  and Yunnan Provinces were clustered in another subgroup. Given that the member of the second group could  infect the cultivar N:Co376, which is immune to the races 1 and 2, our results suggest that majority of U.  scitaminea in sugarcane-producing regions of Southern China may belong to or genetically similar to race 3.Key words: Ustilago scitaminea, sugarcane, inter-simple sequence repeat (ISSR), random amplified  polymorphic deoxyribonucleic acid (DNA) (RAPD), genetic diversity

Death effector domain-containing protein induces vulnerability to cell cycle inhibition in triple-negative breast cancer

Lacking targetable molecular drivers, triple-negative breast cancer (TNBC) is the most clinically challenging subtype of breast cancer. In this study, we reveal that Death Effector Domain-containing DNA-binding protein (DEDD), which is overexpressed in > 60% of TNBCs, drives a mitogen-independent G1/S cell cycle transition through cytoplasm localization. The gain of cytosolic DEDD enhances cyclin D1 expression by interacting with heat shock 71 kDa protein 8 (HSC70). Concurrently, DEDD interacts with Rb family proteins and promotes their proteasome-mediated degradation. DEDD overexpression renders TNBCs vulnerable to cell cycle inhibition. Patients with TNBC have been excluded from CDK 4/6 inhibitor clinical trials due to the perceived high frequency of Rb-loss in TNBCs. Interestingly, our study demonstrated that, irrespective of Rb status, TNBCs with DEDD overexpression exhibit a DEDD-dependent vulnerability to combinatorial treatment with CDK4/6 inhibitor and EGFR inhibitor in vitro and in vivo. Thus, our study provided a rationale for the clinical application of CDK4/6 inhibitor combinatorial regimens for patients with TNBC