Polarization in Quasirelativistic Graphene Model with Topologically Non-Trivial Charge Carriers

Within the earlier developed high-energy-k→·p→-Hamiltonian approach to describe graphene-like materials, the simulations of band structure, non-Abelian Zak phases and the complex conductivity of graphene have been performed. The quasi-relativistic graphene model with a number of flavors (gauge fields) NF=3 in two approximations (with and without a pseudo-Majorana mass term) has been utilized as a ground for the simulations. It has been shown that Zak-phases set for the non-Abelian Majorana-like excitations (modes) in graphene represent the cyclic Z12 and this group is deformed into a smaller one Z8 at sufficiently high momenta due to a deconfinement of the modes. Simulations of complex longitudinal low-frequency conductivity have been performed with a focus on effects of spatial dispersion. A spatial periodic polarization in the graphene models with the pseudo Majorana charge carriers is offered.

Influence of Spatial Dispersion on the Electromagnetic Properties of Magnetoplasmonic Nanostructures

Magnetoplasmonics based on composite nanostructures is widely used in many biomedical applications. Nanostructures, consisting of a magnetic core and a gold shell, exhibit plasmonic properties, that allow the concentration of electromagnetic energy in ultra-small volumes when used, for example, in imaging and therapy. Magnetoplasmonic nanostructures have become an indispensable tool in nanomedicine. The gold shell protects the core from oxidation and corrosion, providing a biocompatible platform for tumor imaging and cancer treatment. By adjusting the size of the core and the shell thickness, the maximum energy concentration can be shifted from the ultraviolet to the near infrared, where the depth of light penetration is maximum due to low scattering and absorption by tissues. A decrease in the thickness of the gold shell to several nanometers leads to the appearance of the quantum effect of spatial dispersion in the metal. The presence of the quantum effect can cause both a significant decrease in the level of energy concentration by plasmon particles and a shift of the maxima to the short-wavelength region, thereby reducing the expected therapeutic effect. In this study, to describe the influence of the quantum effect of spatial dispersion, we used the discrete sources method, which incorporates the generalized non-local optical response theory. This approach made it possible to account for the influence of the nonlocal effect on the optical properties of composite nanoparticles, including the impact of the asymmetry of the core-shell structure on the energy characteristics. It was found that taking spatial dispersion into account leads to a decrease in the maximum value of the concentration of electromagnetic energy up to 25%, while the blue shift can reach 15 nm.

Safe electrophysiologic profile of dexmedetomidine in different experimental arrhythmia models

Previous studies suggest an impact of dexmedetomidine on cardiac electrophysiology. However, experimental data is sparse. Therefore, purpose of this study was to investigate the influence of dexmedetomidine on different experimental models of proarrhythmia. 50 rabbit hearts were explanted and retrogradely perfused. The first group (n = 12) was treated with dexmedetomidine in ascending concentrations (3, 5 and 10 µM). Dexmedetomidine did not substantially alter action potential duration (APD) but reduced spatial dispersion of repolarization (SDR) and rendered the action potentials rectangular, resulting in no proarrhythmia. In further 12 hearts, erythromycin (300 µM) was administered to simulate long-QT-syndrome-2 (LQT2). Additional treatment with dexmedetomidine reduced SDR, thereby suppressing torsade de pointes. In the third group (n = 14), 0.5 µM veratridine was added to reduce the repolarization reserve. Further administration of dexmedetomidine did not influence APD, SDR or the occurrence of arrhythmias. In the last group (n = 12), a combination of acetylcholine (1 µM) and isoproterenol (1 µM) was used to facilitate atrial fibrillation. Additional treatment with dexmedetomidine prolonged the atrial APD but did not reduce AF episodes. In this study, dexmedetomidine did not significantly alter cardiac repolarization duration and was not proarrhythmic in different models of ventricular and atrial arrhythmias. Of note, dexmedetomidine might be antiarrhythmic in acquired LQT2 by reducing SDR.

Influence of Spatial Dispersion on Propagation Properties of Waveguides Based on Hyperbolic Metamaterial

In this work, we study the effect of spatial dispersion on propagation properties of planar waveguides with the core layer formed by hyperbolic metamaterial (HMM). In our case, the influence of spatial dispersion was controlled by changing the unit cell’s dimensions. Our analysis revealed a number of new effects arising in the considered waveguides, which cannot be predicted with the help of local approximation, including mode degeneration (existence of additional branch of TE and TM high-β modes), power flow inversion, propagation gap, and plasmonic-like modes characterized with long distance propagation. Additionally, for the first time we reported unusual characteristic points appearing for the high-β TM mode of each order corresponding to a single waveguide width for which power flow tends to zero and mode stopping occurs.

An Investigation of the Factors that Influence User Acceptance of Mobile information Systems in the Workplace

<p>Mobile information systems (IS) such as field force automation and mobile office applications are rapidly being adopted by a large number of organizations. Despite its popularity and widespread adoption, the body of knowledge regarding user acceptance of mobile information systems in the workplace still is largely anecdotal. The purpose of this study was to develop and rigorously test a model of the factors that influence user acceptance of mobile information systems in the workplace. A thorough review of relevant literature in electronic business, mobile business, user acceptance of technology and user acceptance of mobile technology provided the basis for the development of the conceptual model that guided this research. The model hypothesized that temporal, spatial and structural characteristics of the portfolio of tasks performed by users of mobile information systems in the workplace (namely, temporal requirements of job, spatial dispersion of job, spatial dependence of job, job structuredness and job interdependence) would influence their perceived individual need for mobile information systems (PINMIS). It also suggested that the perceived individual need for mobile IS would influence the performance expectancy as well as intention to use mobile IS. In addition, the model posed that system portability would influence effort expectancy and intention to use mobile IS. In order to develop a research instrument, construct domains were specified and an initial set of items was generated. This was followed by an extensive purification process which consisted of card sorting and expert review rounds, survey pre-tests as well as a pilot study with 234 respondents from a large telecommunications company in New Zealand. The results obtained in this stage helped to refine the measurements and provided the foundations for the main study. The main study was based on a survey with 309 respondents from a wide range of organizations in New Zealand. Using Partial-Least-Squares (PLS) the data collected in the main study was used to test the model. The model was successfully validated and statistically significant evidence was provided that temporal requirements of job, spatial dispersion of job, spatial freedom of job and job interdependence positively influenced PINMIS. On the other hand, job structuredness did not significantly influence PINMIS. It was also found that PINMIS significantly influences performance expectancy and that system portability has a positive effect over effort expectancy as well as intentions to use mobile IS.</p>

An Investigation of the Factors that Influence User Acceptance of Mobile information Systems in the Workplace

<p>Mobile information systems (IS) such as field force automation and mobile office applications are rapidly being adopted by a large number of organizations. Despite its popularity and widespread adoption, the body of knowledge regarding user acceptance of mobile information systems in the workplace still is largely anecdotal. The purpose of this study was to develop and rigorously test a model of the factors that influence user acceptance of mobile information systems in the workplace. A thorough review of relevant literature in electronic business, mobile business, user acceptance of technology and user acceptance of mobile technology provided the basis for the development of the conceptual model that guided this research. The model hypothesized that temporal, spatial and structural characteristics of the portfolio of tasks performed by users of mobile information systems in the workplace (namely, temporal requirements of job, spatial dispersion of job, spatial dependence of job, job structuredness and job interdependence) would influence their perceived individual need for mobile information systems (PINMIS). It also suggested that the perceived individual need for mobile IS would influence the performance expectancy as well as intention to use mobile IS. In addition, the model posed that system portability would influence effort expectancy and intention to use mobile IS. In order to develop a research instrument, construct domains were specified and an initial set of items was generated. This was followed by an extensive purification process which consisted of card sorting and expert review rounds, survey pre-tests as well as a pilot study with 234 respondents from a large telecommunications company in New Zealand. The results obtained in this stage helped to refine the measurements and provided the foundations for the main study. The main study was based on a survey with 309 respondents from a wide range of organizations in New Zealand. Using Partial-Least-Squares (PLS) the data collected in the main study was used to test the model. The model was successfully validated and statistically significant evidence was provided that temporal requirements of job, spatial dispersion of job, spatial freedom of job and job interdependence positively influenced PINMIS. On the other hand, job structuredness did not significantly influence PINMIS. It was also found that PINMIS significantly influences performance expectancy and that system portability has a positive effect over effort expectancy as well as intentions to use mobile IS.</p>