An ion-trap CID MS/MS spectral database of 505 doubly protonated tryptic peptides was used to investigate the influence of an internal basic residue on preferential fragmentation C-terminal to the acidic amino acid residues, aspartic acid (Asp) and glutamic acid (Glu). Because tryptic peptides, which contain C-terminal Lys or Arg, were selected for analysis, the majority of the peptides contain...

The excitation spectrum of the one-dimensional spin-orbital model in a magnetic field is studied, using a recently developed dynamical density matrix renormalization group technique. The method is employed on chains with up to 80 sites, and examined for test cases such as the spin-1/2 antiferromagnetic Heisenberg chain, where the excitation spectrum is known exactly from the Bethe Ansatz. In th...

Taking the isotropic limit ∆ → 1 in a recent representation theoretic construction of Baxter’s Q-operators for the XXZ model with quasi-periodic boundary conditions we obtain new results for the XXX model. We show that quasi-periodic boundary conditions are needed to ensure convergence of the Q-operator construction and derive a quantum Wronskian relation which implies two different sets of Bet...

We develop the quantum inverse scattering method for the one-dimensional Hubbard model on the infinite interval at zero density. R-matrix and monodromy matrix are obtained as limits from their known counterparts on the finite interval. The R-matrix greatly simplifies in the considered limit. The new R-matrix contains a submatrix which turns into the rational R-matrix of the XXX-chain by an appr...

Quantum phase transitional behavior of a finite periodic XX spin1 2 chain with nearest neighbor interaction in a uniform transverse field is studied based on the simple exact solutions. It is found that there are [N/2] quantum critical points in the ground state, where N is the periodic number of the system and [x] stands for the integer part of x, when the interaction strength and magnitude of...

We introduce a new concept of quasi-Yang-Baxter algebras. The quantum quasiYang-Baxrer algebras being simple but non-trivial deformations of ordinary algebras of monodromy matrices realize a new type of quantum dynamical symmetries and nd an unexpected and remarkable applications in quantum inverse scattering method (QISM). We show that applying to quasi-Yang-Baxter algebras the standard proced...

Email for correspondence: [email protected] A. Balseiro, XXX, A. Oleaga, XXX, Servico Regionel de Investigación y Desarrollo Agroalimentario, Labarotorio de Sanidad Animal, 33299 Jove, Gijón, Asturias, Spain R. Orusa, XXX, S. Robetto, XXX, L. Domenis, XXX, Area Territoriale di Aosta/Cermas (Centro di Referenza Nazionale per le Malattie degli Animali Selvatici) S. Zoppi, XXX, A. Dondo, XXX, A...

Recently there has been much interest in the study of finite one-dimensional quantum spin chains following the discovery of fractional S = —, ' spin states localized at the ends of S = 1 spin chains. ' In a recent paper, we showed numerically that the S = —, ' spin states can be understood within the framework of the Schwinger-boson mean-field theory (SBMFT) for the Heisenberg model. ' In this ...

We prove that in the presence of a maximal giant graviton state in N = 4 SYM, the states dual to open strings attached to the giant graviton give rise to an PSU(2, 2|4) open spin chain model with integrable boundary conditions in the SO(6) sector of the spin chain to one loop order.