2,416 research outputs found

    Interface of the polarizable continuum model of solvation with semi-empirical methods in the GAMESS program

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    An interface between semi-empirical methods and the polarized continuum model (PCM) of solvation successfully implemented into GAMESS following the approach by Chudinov et al (Chem. Phys. 1992, 160, 41). The interface includes energy gradients and is parallelized. For large molecules such as ubiquitin a reasonable speedup (up to a factor of six) is observed for up to 16 cores. The SCF convergence is greatly improved by PCM for proteins compared to the gas phase

    Mapping Enzymatic Catalysis using the Effective Fragment Molecular Orbital Method: Towards all ab initio Biochemistry

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    We extend the Effective Fragment Molecular Orbital (EFMO) method to the frozen domain approach where only the geometry of an active part is optimized, while the many-body polarization effects are considered for the whole system. The new approach efficiently mapped out the entire reaction path of chorismate mutase in less than four days using 80 cores on 20 nodes, where the whole system containing 2398 atoms is treated in the ab initio fashion without using any force fields. The reaction path is constructed automatically with the only assumption of defining the reaction coordinate a priori. We determine the reaction barrier of chorismate mutase to be 18.3±3.518.3\pm 3.5 kcal mol1^{-1} for MP2/cc-pVDZ and 19.3±3.619.3\pm 3.6 for MP2/cc-pVTZ in an ONIOM approach using EFMO-RHF/6-31G(d) for the high and low layers, respectively.Comment: SI not attache

    Hybrid RHF/MP2 geometry optimizations with the Effective Fragment Molecular Orbital Method

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    The frozen domain effective fragment molecular orbital method is extended to allow for the treatment of a single fragment at the MP2 level of theory. The approach is applied to the conversion of chorismate to prephenate by chorismate mutase, where the substrate is treated at the MP2 level of theory while the rest of the system is treated at the RHF level. MP2 geometry optimization is found to lower the barrier by up to 3.5 kcal/mol compared to RHF optimzations and ONIOM energy refinement and leads to a smoother convergence with respect to the basis set for the reaction profile. For double zeta basis sets the increase in CPU time relative to RHF is roughly a factor of two.Comment: 11 pages, 3 figure

    Infrared cutoffs and the adiabatic limit in noncommutative spacetime

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    We discuss appropriate infrared cutoffs and their adiabatic limit for field theories on the noncommutative Minkowski space in the Yang-Feldman formalism. In order to do this, we consider a mass term as interaction term. We show that an infrared cutoff can be defined quite analogously to the commutative case and that the adiabatic limit of the two-point function exists and coincides with the expectation, to all orders.Comment: 19 page

    Perturbative Quantum Field Theory at Positive Temperatures: An Axiomatic Approach

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    It is shown that the perturbative expansions of the correlation functions of a relativistic quantum field theory at finite temperature are uniquely determined by the equations of motion and standard axiomatic requirements, including the KMS condition. An explicit expression as a sum over generalized Feynman graphs is derived. The canonical formalism is not used, and the derivation proceeds from the beginning in the thermodynamic limit. No doubling of fields is invoked. An unsolved problem concerning existence of these perturbative expressions is pointed out.Comment: 17pages Late

    RHABDOMYOLYSIS INDUCED BY ANAESTHESIA WITH INTRAOPERATIVE CARDIAC ARREST

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    A 9-year-old boy undergoing anaesthesia including suxamethonium and halothane suffered cardiac arrest on two occasions. Clinical and laboratory examination subsequently showed that the patient had suffered from acute rhabdomyolysis. The eventual recovery was satisfactor

    Heterologous vaccine regimen: stakeholder acceptance and implementation considerations

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    Heterologous vaccine regimens deliver antigens through different vaccine components or vector types at sequential time points. Clinical development shows promising results and several candidates may be progressing to licensure in the coming years. This study aimed at exploring future acceptance and uptake of such regimens (also called heterologous prime-boost) and to identify implementation-associated benefits and challenges. Survey tools were developed based on findings from a previous literature search shared with the study team, and exploratory interviews with global stakeholders. An online survey and key informant interviews in six countries were conducted with stakeholders at national and sub-national level, including policy-makers, regulators and implementers. The interview guide and the online survey covered: (a) awareness of, and knowledge about, heterologous vaccine regimens; (b) rating of regimenassociated perceived benefits and challenges; (c) anticipation of possible challenges in relation to four hypothetical introduction scenarios; (d) potential acceptance benefits and challenges at the policy, health facility and recipient level. Sixty-two interviews were conducted at national level. The online survey was completed by 50 participants. Across the four introduction scenarios, respondents considered the highest potential for the introduction of heterologous regimens for immunoprophylaxis was among adolescents/ adults for diseases against which no vaccines are currently available. Most reservations were related to logistics, record keeping, and recipient compliance. Adding a new heterologous vaccine regimen to the routine immunization calendar for children was considered feasible if it could generate an increased and longer-term immune response. Introduction in preparation of or following a disease outbreak was considered less favourably, with respondents stressing the difficulty of logistics in emergency situations, and the potential lag in the onset of protection. The recent approval of the first heterologous vaccine regimen for the prevention of Ebola Virus Disease will soon bring new light to the topic
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