Two-photon Rabi model: Analytic solutions and spectral collapse

The two-photon quantum Rabi model with quadratic coupling is studied using extended squeezed states and we derive $G$-functions for Bargmann index $q=1/4$ and $3/4$. The simple singularity structure of the $G$-function allows to draw conclusions about the distribution of eigenvalues along the real axis. The previously found picture of the spectral collapse at critical coupling $g_{\mathrm{c}}$ has to be modified regarding the low lying states, especially the ground state: We obtain a finite gap between ground state and the continuum of excited states at the collapse point. For large qubit splitting, also other low lying states may be separated from the continuum at $g_{\mathrm{c}}$. We have carried out a perturbative analysis allowing for explicit and simple formulae of the eigenstates. Interestingly, a vanishing of the gap between ground state and excited continuum at $g_{\mathrm{c}}$ is obtained in each finite order of approximation. This demonstrates cleary the non-pertubative nature of the excitation gap. We corroborate these findings with a variational calculation for the ground state.Comment: 13 pages, 4 figure

The hidden symmetry of the asymmetric two-photon Rabi model

In this paper, we derive the symmetry operators ($J$'s) in the asymmetric two-photon quantum Rabi models in terms of Bogoliubov operator approaches. $J^2$ can be expressed as a polynomial in terms of the Hamiltonian, which uncovers the $\mathbb{Z}_{2}$ nature of the hidden symmetry in this two-photon model rigorously. The previous symmetry operators in the asymmetric one-photon quantum Rabi models are reproduced readily in terms of Bogoliubov operator approaches, and the obtained operators are expressed much more concisely. It is found that the polynomial degree of $J^2$ in the two-photon model is twice of that in the one-photon model.Comment: 6 pages. arXiv admin note: text overlap with arXiv:2102.0394

The γ-gliadin multigene family in common wheat (Triticum aestivum) and its closely related species

<p>Abstract</p> <p>Background</p> <p>The unique properties of wheat flour primarily depend on gluten, which is the most important source of protein for human being. γ-Gliadins have been considered to be the most ancient of the wheat gluten family. The complex family structure of γ-gliadins complicates the determination of their function. Moreover, γ-gliadins contain several sets of celiac disease epitopes. However, no systematic research has been conducted yet.</p> <p>Results</p> <p>A total of 170 γ-gliadin genes were isolated from common wheat and its closely related species, among which 138 sequences are putatively functional. The ORF lengths of these sequences range from 678 to 1089 bp, and the repetitive region is mainly responsible for the size heterogeneity of γ-gliadins. The repeat motif <b>P</b>(Q/L/S/T/I/V/R/A)<b>F</b>(S/Y/V/Q/I/C/L)<b>P</b>(R/L/S/T/H/C/Y)<b>Q</b>_1–2<b>(P</b>(S/L/T/A/F/H)<b>QQ)</b>_1–2is repeated from 7 to 22 times. Sequence polymorphism and linkage disequilibrium analyses show that γ-gliadins are highly diverse. Phylogenic analyses indicate that there is no obvious discrimination between <it>Sitopsis </it>and <it>Ae. tauschii </it>at the <it>Gli-1 </it>loci, compared with diploid wheat. According to the number and placement of cysteine residues, we defined nine cysteine patterns and 17 subgroups. Alternatively, we classified γ-gliadins into two types based on the length of repetitive domain. Amino acid composition analyses indicate that there is a wide range of essential amino acids in γ-gliadins, and those γ-gliadins from subgroup SG-10 and SG-12 and γ-gliadins with a short repetitive domain are more nutritional. A screening of toxic epitopes shows that γ-gliadins with a pattern of C9 and γ-gliadins with a short repetitive domain almost lack any epitopes.</p> <p>Conclusion</p> <p>γ-Gliadin sequences in wheat and closely related <it>Aegilops </it>species are diverse. Each group/subgroup contributes differently to nutritional quality and epitope content. It is suggested that the genes with a short repetitive domain are more nutritional and valuable. Therefore, it is possible to breed wheat varieties, the γ-gliadins of which are less, even non-toxic and more nutritional.</p

Polymorphisms at the TNF Locus in Chinese Han Population

ABSTRACT: One hundred sixty-four unrelated healthy individuals from Chinese Han population were investigated in order to define the distribution of eight polymorphic loci within the tumor necrosis factor (TNF) gene cluster and determine their relationship between the high polymorphic microsatellite TNFa, b, d, and other elements. The cloning and sequencing for five microsatellites were simultaneously done. In this study, the distribution of TNF alleles apparently vary from other ethnic groups. A new allele was detected and confirmed. It should be emphasized that a very strong association between TNFd8 and TNFe4 is reported and d8e4 haplotype appears to be specific to the population studied. In addition, five extended haplotypes were established in this population: a6b5c1d8e4TNF308-1TNF-␤Nco1-1TNFAspH1-2, a2b1c2d5e1TNF308-1TNF-␤Nco1-2TNFAspH1-2, a11b4c1d4e3TNF308-1TNF-␤Nco1-2TNFAspH1-1, a10b4c1d4e3TNF308-1TNF-␤Nco1-2TNFAspH1-1, and a2b3c1d2e3TNF308-2TNFAspH1-2. Data suggest that important ethnic differences may exist and that it is a necessary initiative for further research. Human Immunology 63, 71-75 (2002)