Doctor of Philosophy

dissertationNizio l proved a p-adic comparison isomorphism of semistable schemes via K-theory. In this paper, we generalize it to integral setting; to make the classical argument work, we need the Gysin map and Grothendieck-Riemann-Roch in the log crystalline setting, and we generalize the method of Berthelot, and Gillet-Messing, respectively

Transport properties of quantum dot molecules and electronic structure of graphene quantum dot qubits

Coupled Quantum dots systems, or quantum dot molecules (QDMs), have been suggested as good candidates for nanoelectronics, spintronics, thermoelectrics, and quantum computing applications. The knowledge in the transport and electronic properties of QDMs is important in making progress toward practical devices. We use many-body equation of motion method for Hubbard-Anderson model to study non-equilibrium charge and thermal transport properties of QDMs connected to metallic electrodes in the Coulomb blockade regime. An exterior algebra method is developed to construct the equation of motion computationally, taking into account all correlation functions. The quantum interference (QI) effect of triangular quantum dot molecule (TQDM) resulting from electron coherent tunneling between quantum dots is revealed. The spectra of electrical conductance of TQDM with charge filling from one to six electrons clearly depict the many-body and topological effects. The calculated charge stability diagram for conductance and total occupation numbers match well with the recent experimental measurements. We also demonstrate that the destructive QI effect on the tunneling current of TQDM is robust with respect to temperature variation, making the single electron QI transistor feasible at higher temperatures. The thermoelectric properties of QDMs with high figure of merit are also illustrated. Graphene nanoribbon quantum dot qubits have been proposed as promising candidates for quantum computing applications to overcome the spin-decoherence problems associated with GaAs quantum dot qubits. We perform theoretical studies of the electronic structures of graphene nanoribbon quantum dots by solving the Dirac equation with appropriate boundary conditions. We then evaluate the exchange splitting based on an unrestricted Hartree-Fock method for the Dirac particles. The electronic wave function and long-range exchange coupling due to the Klein tunneling and the Coulomb interaction are calculated for various gate configurations. It is found that the exchange coupling between qubits can be significantly enhanced by the Klein tunneling effect. The implications of our results for practical qubit construction and operation are discussed

Effective superior vena cava isolation using a novel C-shaped approach

IntroductionSuperior vena cava (SVC) isolation has been proposed as part of the ablation strategy for atrial fibrillation. However, circumferential isolation of the SVC can lead to late-onset complications, such as SVC stenosis.MethodsWe describe a detailed observation of the SVC conduction pattern and present a newly developed approach for SVC isolation that involves creating a C-shaped non-circumferential ablation line while sparing the lateral segment.ResultsTwelve consecutive patients were included in the study, all of whom achieved bidirectional block during the ablation procedure.DiscussionThis approach to SVC isolation is effective and has the potential to reduce ablation related complications; however, larger studies and long-term follow-up is warranted to confirm these findings

(PS)(2): protein structure prediction server

Protein structure prediction provides valuable insights into function, and comparative modeling is one of the most reliable methods to predict 3D structures directly from amino acid sequences. However, critical problems arise during the selection of the correct templates and the alignment of query sequences therewith. We have developed an automatic protein structure prediction server, (PS)(2), which uses an effective consensus strategy both in template selection, which combines PSI-BLAST and IMPALA, and target–template alignment integrating PSI-BLAST, IMPALA and T-Coffee. (PS)(2) was evaluated for 47 comparative modeling targets in CASP6 (Critical Assessment of Techniques for Protein Structure Prediction). For the benchmark dataset, the predictive performance of (PS)(2), based on the mean GTD_TS score, was superior to 10 other automatic servers. Our method is based solely on the consensus sequence and thus is considerably faster than other methods that rely on the additional structural consensus of templates. Our results show that (PS)(2), coupled with suitable consensus strategies and a new similarity score, can significantly improve structure prediction. Our approach should be useful in structure prediction and modeling. The (PS)(2) is available through the website at