119 research outputs found
Relationship between nucleic acid sequence, structure and function in terms of stabilizing interactions
The relationship between nucleic acid (NA) sequence, structure and function is intricately connected to the stabilizing interactions (primarily hydrogen bonding and 1t-stacking) that occur between the monomeric subunits that constitute NAs. Therefore, detailed insights into the. nature of the stabilizing interactions would permit the full exploitation of the structure-function relationship in NAs. A complete understanding of the role of the stabilizing interactions in NAs involves the fulfillment of two requirements: 1) The ability to determine the electronic structure of the monomeric units (in terms of the electron density distribution as an observable) that make up the fundamental structure of NAs, which is possible through the use of quantum chemical calculations, and 2) The ability to characterize the electronic structure of these monomeric units in the context of realistic NA structures. Ideally, such molecular structures are determined experimentally. These two ideas are combined into a methodology that has been designed, tested and validated in the work presented here. The proof of concept culminates in the ability of the methodology to exploit the structure-function relationship in NAs through procurement of full stabilization profiles of host NA and guest (small molecule inhibitors to the function of the NA) complexes, where the potential inhibitors were designed on the basis of the stabilization profiles of the host and natural ligand complexe
New concept of relativistic invariance in NC space-time: twisted Poincar\'e symmetry and its implications
We present a systematic framework for noncommutative (NC) QFT within the new
concept of relativistic invariance based on the notion of twisted Poincar\'e
symmetry (with all 10 generators), as proposed in ref. [7]. This allows to
formulate and investigate all fundamental issues of relativistic QFT and offers
a firm frame for the classification of particles according to the
representation theory of the twisted Poincar\'e symmetry and as a result for
the NC versions of CPT and spin-statistics theorems, among others, discussed
earlier in the literature. As a further application of this new concept of
relativism we prove the NC analog of Haag's theorem.Comment: 15 page
Empowered but not Equal: Challenging the Traditional Gender Roles as Seen by University Students in Saudi Arabia
This study examines perspectives of Saudi university students regarding changing gender roles as affected by women’s rights, education, employment, and activity in the public sphere. Results from a questionnaire distributed among 4,455 male and female students indicate students are confident and optimistic about improving gender equity, however resistance from those holding traditional views still exist. Female respondents are more optimistic than male respondents,seeing changes in gender roles as advantageous to their personal and professional lives. Representing a group of allies, a majority of male students regard changing gender roles positively. Men and women reported personal courage to address these challenges, which is an asset moving forward. While approval will never reach consensus,changes may be forthcoming. By surveying the Saudi university population, this study seeks to inform strategy and policy. Gender equity is only possible through increased societal acceptance of women’s freedom in their everyday lives
Research in technology education: Looking back to move forward
This paper attempts to summarize the focus of the research that has recently taken place in Technology Education, and from that basis suggest a trajectory for future research trends. Some research that is considered particularly seminal to the profession is summarised, and the paper is concluded with some reflections about personal research agendas
Deterministic constant-temperature dynamics for dissipative quantum systems
A novel method is introduced in order to treat the dissipative dynamics of
quantum systems interacting with a bath of classical degrees of freedom. The
method is based upon an extension of the Nos\`e-Hoover chain (constant
temperature) dynamics to quantum-classical systems. Both adiabatic and
nonadiabatic numerical calculations on the relaxation dynamics of the
spin-boson model show that the quantum-classical Nos\`e-Hoover chain dynamics
represents the thermal noise of the bath in an accurate and simple way.
Numerical comparisons, both with the constant energy calculation and with the
quantum-classical Brownian motion treatment of the bath, show that the
quantum-classical Nos\`e-Hoover Chain dynamics can be used to introduce
dissipation in the evolution of a quantum subsystem even with just one degree
of freedom for the bath. The algorithm can be computationally advantageous in
modeling, within computer simulation, the dynamics of a quantum subsystem
interacting with complex molecular environments.Comment: Revised versio
Transport Equations from Liouville Equations for Fractional Systems
We consider dynamical systems that are described by fractional power of
coordinates and momenta. The fractional powers can be considered as a
convenient way to describe systems in the fractional dimension space. For the
usual space the fractional systems are non-Hamiltonian. Generalized transport
equation is derived from Liouville and Bogoliubov equations for fractional
systems. Fractional generalization of average values and reduced distribution
functions are defined. Hydrodynamic equations for fractional systems are
derived from the generalized transport equation.Comment: 11 pages, LaTe
On "full" twisted Poincare' symmetry and QFT on Moyal-Weyl spaces
We explore some general consequences of a proper, full enforcement of the
"twisted Poincare'" covariance of Chaichian et al. [14], Wess [50], Koch et al.
[34], Oeckl [41] upon many-particle quantum mechanics and field quantization on
a Moyal-Weyl noncommutative space(time). This entails the associated braided
tensor product with an involutive braiding (or -tensor product in the
parlance of Aschieri et al. [3,4]) prescription for any coordinates pair of
generating two different copies of the space(time); the associated
nontrivial commutation relations between them imply that is central and
its Poincar\'e transformation properties remain undeformed. As a consequence,
in QFT (even with space-time noncommutativity) one can reproduce notions (like
space-like separation, time- and normal-ordering, Wightman or Green's
functions, etc), impose constraints (Wightman axioms), and construct free or
interacting theories which essentially coincide with the undeformed ones, since
the only observable quantities involve coordinate differences. In other words,
one may thus well realize QM and QFT's where the effect of space(time)
noncommutativity amounts to a practically unobservable common noncommutative
translation of all reference frames.Comment: Latex file, 24 pages. Final version to appear in PR
Quantum Kinetic Evolution of Marginal Observables
We develop a rigorous formalism for the description of the evolution of
observables of quantum systems of particles in the mean-field scaling limit.
The corresponding asymptotics of a solution of the initial-value problem of the
dual quantum BBGKY hierarchy is constructed. Moreover, links of the evolution
of marginal observables and the evolution of quantum states described in terms
of a one-particle marginal density operator are established. Such approach
gives the alternative description of the kinetic evolution of quantum
many-particle systems to generally accepted approach on basis of kinetic
equations.Comment: 18 page
The von Neumann Hierarchy for Correlation Operators of Quantum Many-Particle Systems
The Cauchy problem for the von Neumann hierarchy of nonlinear equations is
investigated. One describes the evolution of all possible states of quantum
many-particle systems by the correlation operators. A solution of such
nonlinear equations is constructed in the form of an expansion over particle
clusters whose evolution is described by the corresponding order cumulant
(semi-invariant) of evolution operators for the von Neumann equations. For the
initial data from the space of sequences of trace class operators the existence
of a strong and a weak solution of the Cauchy problem is proved. We discuss the
relationships of this solution both with the -particle statistical
operators, which are solutions of the BBGKY hierarchy, and with the
-particle correlation operators of quantum systems.Comment: 26 page
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