Production and decay of the neutral top-pion in high energy e+e−e^{+}e^{-} colliders

We study the production and decay of the neutral top-pion $\pi_{t}^{0}$ predicted by topcolor-assisted technicolor(TC2) theory. Our results show that, except the dominant decay modes $b\bar{b}$, $\bar{t}c$ and $gg$, the $\pi_{t}^{0}$ can also decay into $\gamma\gamma$ and $Z \gamma$ modes. It can be significantly produced at high energy $e^{+}e^{-}$ collider(LC) experiments via the processes $e^{+}e^{-}\to \pi_{t}^{0}\gamma$ and $e^{+}e^{-}\to Z\pi_{t}^{0}$. We further calculate the production cross sections of the processes $e^{+}e^{-}\to\gamma\pi_{t}^{0}\to\gamma\bar{t}c$ and $e^{+}e^{-}\to Z\pi_{t}^{0}\to Z\bar{t}c$. We find that the signatures of the neutral top-pion $\pi_{t}^{0}$ can be detected via these processes.Comment: Latex file, 13 Pages, 6 eps figures. to be published in Phys.Rev.

Signature of same-sign top pair production mediated by a nonuniversal Z′Z^\prime with QCD next-to-leading accuracy at the LHC

We present a detailed study of the same-sign top pair production mediated by a non-universal $Z^\prime$ including production and decay at the Large Hadron Collider (LHC) at the QCD next-to-leading order (NLO) level, using the narrow width approximation and helicity amplitudes method. We find that the QCD NLO corrections can loose the constraint on the model parameters and reduce the dependence of the total cross sections on the factorization scale significantly. We also study the signature and backgrounds of the process at the NLO level. In order to suppress the backgrounds, we further investigate the difference between the production rates of the positively and negatively charged dilepton at the LHC, and find that the same-sign dilepton signal of the new physics could be discovered more easily.Comment: 24 pages, 14 figures, 2 table. final version in PRD. arXiv admin note: text overlap with arXiv:1103.512

Restriction landmark genomic scanning (RLGS) spot identification by second generation virtual RLGS in multiple genomes with multiple enzyme combinations.

BackgroundRestriction landmark genomic scanning (RLGS) is one of the most successfully applied methods for the identification of aberrant CpG island hypermethylation in cancer, as well as the identification of tissue specific methylation of CpG islands. However, a limitation to the utility of this method has been the ability to assign specific genomic sequences to RLGS spots, a process commonly referred to as "RLGS spot cloning."ResultsWe report the development of a virtual RLGS method (vRLGS) that allows for RLGS spot identification in any sequenced genome and with any enzyme combination. We report significant improvements in predicting DNA fragment migration patterns by incorporating sequence information into the migration models, and demonstrate a median Euclidian distance between actual and predicted spot migration of 0.18 centimeters for the most complex human RLGS pattern. We report the confirmed identification of 795 human and 530 mouse RLGS spots for the most commonly used enzyme combinations. We also developed a method to filter the virtual spots to reduce the number of extra spots seen on a virtual profile for both the mouse and human genomes. We demonstrate use of this filter to simplify spot cloning and to assist in the identification of spots exhibiting tissue-specific methylation.ConclusionThe new vRLGS system reported here is highly robust for the identification of novel RLGS spots. The migration models developed are not specific to the genome being studied or the enzyme combination being used, making this tool broadly applicable. The identification of hundreds of mouse and human RLGS spot loci confirms the strong bias of RLGS studies to focus on CpG islands and provides a valuable resource to rapidly study their methylation

Sialic acid profiles in the respiratory tracts of selected species of raptors: evidence for potential binding sites for human and avian influenza A viruses

Abstract Context. The ability of influenza A viruses to recognise and bind to cell surface receptors such as sialic acid linked to galactose by an a2,3 linkage (SAa2,3-gal) and sialic acid linked to galactose by an a2,6 linkage (SAa2,6-gal) is a major determinant of influenza A virus infection. Although the epidemiological surveys of influenza A virus infection in raptors suggest that some raptor species are susceptible to influenza A viruses under natural conditions, the sialic acid profiles in the respiratory and intestinal tracts of raptors are unknown. Aims. To examine the sialic acid receptor profiles in the respiratory tracts of the selected raptor species and assess the potential susceptibility of raptors to avian and human influenza viruses and the role of raptors in the epidemiology and evolution of influenza A viruses. Methods. The lectin immunohistochemistry staining method was used to examine the sialic acid profiles in the respiratory tracts of eight different species of raptors. Key results. A strong staining with Maackia amurensis agglutinin (MAA), specific for sialic acid linked to galactose by an a2,3 linkage (SAa2,3-gal), was observed in the epithelial cells of the respiratory tract of Accipiter nisus and Falco tinnunculus. However, a positive staining for both MAA and Sambucus nigra agglutinin (SNA), specific for sialic acid linked to galactose by an a2,6 linkage (SAa2,6-gal), was detected in the epithelial cells of the upper respiratory tract of Accipiter gularis, Buteo buteo, Otus sunia, Bubo bubo and Asio otus, and in the epithelial cells of the alveoli of Buteo buteo, Falco peregrinus, Otus sunia and Bubo bubo. Conclusions. Both avian and human influenza A virus receptors are expressed in six species of raptors examined. There are some variations in the type and distribution of sialic acid receptor expression among different raptor species. No correlation between phylogeny of birds and their sialic acid receptor distributions was observed. Implications. Since SAa2,3-gal and SAa2,6-gal are often considered as the primary receptors for avian influenza A viruses and human influenza A viruses, respectively, our data suggest that raptors could be a potential host for avian and human influenza A viruses

Production of the neutral toppion at the e gamma colliders

In the framework of topcolor-assisted technicolor(TC2) model, we study a neutral toppion production process $e^{-}\gamma\to e^{-}\Pi^{0}_{t}$ in this paper. Our results show that the production cross section of $e^{-}\gamma\to e^{-}\Pi^{0}_{t}$ can reach the level of several tens fb, and over $10^{3}$ neutral toppion events can be produced in the planned $e^+e^-$ linear colliders each year. Therefore, such a toppion production process provides us a unique chance to detect toppion events and test the TC2 model. On the other hand, the cross section of $e^{-}\gamma\to e^{-}\Pi^{0}_{t}$ is about one order of magnitude larger than those of some similar processes in SM and MSSM(i.e., $e^{-}\gamma\to e^{-}H$ in SM and $e^{-}\gamma\to e^{-}H^{0}(A^0,h^0)$ in MSSM). So, we can easily distinguish the neutral toppion from other neutral Higgs bosons in SM and MSSM.Comment: 12 pages, 4 figures, The paper has been accepted by Phys.Rev.

The bracteatus pineapple genome and domestication of clonally propagated crops

Domestication of clonally propagated crops such as pineapple from South America was hypothesized to be a 'one-step operation'. We sequenced the genome of Ananas comosus var. bracteatus CB5 and assembled 513 Mb into 25 chromosomes with 29,412 genes. Comparison of the genomes of CB5, F153 and MD2 elucidated the genomic basis of fiber production, color formation, sugar accumulation and fruit maturation. We also resequenced 89 Ananas genomes. Cultivars 'Smooth Cayenne' and 'Queen' exhibited ancient and recent admixture, while 'Singapore Spanish' supported a one-step operation of domestication. We identified 25 selective sweeps, including a strong sweep containing a pair of tandemly duplicated bromelain inhibitors. Four candidate genes for self-incompatibility were linked in F153, but were not functional in self-compatible CB5. Our findings support the coexistence of sexual recombination and a one-step operation in the domestication of clonally propagated crops. This work guides the exploration of sexual and asexual domestication trajectories in other clonally propagated crops