Subject-specific finite element modelling of the human hand complex : muscle-driven simulations and experimental validation

This paper aims to develop and validate a subject-specific framework for modelling the human hand. This was achieved by combining medical image-based finite element modelling, individualized muscle force and kinematic measurements. Firstly, a subject-specific human hand finite element (FE) model was developed. The geometries of the phalanges, carpal bones, wrist bones, ligaments, tendons, subcutaneous tissue and skin were all included. The material properties were derived from in-vivo and in-vitro experiment results available in the literature. The boundary and loading conditions were defined based on the kinematic data and muscle forces of a specific subject captured from the in-vivo grasping tests. The predicted contact pressure and contact area were in good agreement with the in-vivo test results of the same subject, with the relative errors for the contact pressures all being below 20%. Finally, sensitivity analysis was performed to investigate the effects of important modelling parameters on the predictions. The results showed that contact pressure and area were sensitive to the material properties and muscle forces. This FE human hand model can be used to make a detailed and quantitative evaluation into biomechanical and neurophysiological aspects of human hand contact during daily perception and manipulation. The findings can be applied to the design of the bionic hands or neuro-prosthetics in the future

Integer quantum Hall effect and topological phase transitions in silicene

We numerically investigate the effects of disorder on the quantum Hall effect (QHE) and the quantum phase transitions in silicene based on a lattice model. It is shown that for a clean sample, silicene exhibits an unconventional QHE near the band center, with plateaus developing at $\nu=0,\pm2,\pm6,\ldots,$ and a conventional QHE near the band edges. In the presence of disorder, the Hall plateaus can be destroyed through the float-up of extended levels toward the band center, in which higher plateaus disappear first. However, the center $\nu=0$ Hall plateau is more sensitive to disorder and disappears at a relatively weak disorder strength. Moreover, the combination of an electric field and the intrinsic spin-orbit interaction (SOI) can lead to quantum phase transitions from a topological insulator to a band insulator at the charge neutrality point (CNP), accompanied by additional quantum Hall conductivity plateaus.Comment: 7 pages, 4 figure

Supercritical super-Brownian motion with a general branching mechanism and travelling waves

We consider the classical problem of existence, uniqueness and asymptotics of monotone solutions to the travelling wave equation associated to the parabolic semi-group equation of a super-Brownian motion with a general branching mechanism. Whilst we are strongly guided by the probabilistic reasoning of Kyprianou (2004) for branching Brownian motion, the current paper offers a number of new insights. Our analysis incorporates the role of Seneta-Heyde norming which, in the current setting, draws on classical work of Grey (1974). We give a pathwise explanation of Evans' immortal particle picture (the spine decomposition) which uses the Dynkin-Kuznetsov N-measure as a key ingredient. Moreover, in the spirit of Neveu's stopping lines we make repeated use of Dynkin's exit measures. Additional complications arise from the general nature of the branching mechanism. As a consequence of the analysis we also offer an exact X(log X)^2 moment dichotomy for the almost sure convergence of the so-called derivative martingale at its critical parameter to a non-trivial limit. This differs to the case of branching Brownian motion and branching random walk where a moment `gap' appears in the necessary and sufficient conditions.Comment: 34 page

Evaluation of headspace Solid Phase Micro-extraction method for analysis of phosphine residues in wheat

This new method utilizes headspace-solid-phase micro extraction (HS-SPME) for pre-concentration of PH3. Phosphine was determined with gas chromatography/pulsed flame photometric detector (PFPD). Spiked samples were used for calculation of phosphine residue in grain. Four types of fibres (100μm-PDMS, 85μm- CAR/PDMS, 75μm-CAR/PDMS and 65μm-PDMS/DVB) were tested. The bipolar fibres (CAR/PDMS and PDMS/DVB) can extract PH3, but the non-polar fibre (PDMS) did not. Larger size fibres extracted PH3 more efficiently than the smaller size fibres (e.g., 85 μm > 75 μm > 65 μm). The 85μm CAR/PDMS fibre was used to optimize the different parameters that affect the SPME extraction efficiency of PH3. In the validation study, 50 grams of wheat in a 250 mL glass flask and capped with an open-top screw cap and PTFE/Silicon septa were spiked at 0.02 ng PH3/g of wheat. The flask was then heated to 45°C in an oil bath for 45 min, after which time the 85 μm CAR/PDMS fibre was exposed for 20 min and then exposed in the heated injection port of a GC/PFPD and desorbed for 2 min. Under conditions of the validation study, the limit of detection (LOD) or level of quantification (LOQ) was in the range of 0.005–0.01 ng PH3/g of wheat. Keywords: Fumigant, Phosphine, Residue, SPME, HS-SPM

Possibility of Unconventional Pairing Due to Coulomb Interaction in Fe-Based Pnictide Superconductors: Perturbative Analysis of Multi-Band Hubbard Models

Possibility of unconventional pairing due to Coulomb interaction in iron-pnictide superconductors is studied by applying a perturbative approach to realistic 2- and 5-band Hubbard models. The linearized Eliashberg equation is solved by expanding the effective pairing interaction perturbatively up to third order in the on-site Coulomb integrals. The numerical results for the 5-band model suggest that the eigenvalues of the Eliashberg equation are sufficiently large to explain the actual high Tc for realistic values of Coulomb interaction and the most probable pairing state is spin-singlet s-wave without any nodes just on the Fermi surfaces, although the superconducting order parameter changes its sign between the small Fermi pockets. On the other hand the 2-band model is quite insufficient to explain the actual high Tc.Comment: 2 pages, 3 figures. Proceedings of the Intl. Symposium on Fe-Oxypnictide Superconductors (Tokyo, 28-29th June 2008

Evaluation of headspace Solid Phase Micro-extraction method for analysis of phosphine residues in wheat

This new method utilizes headspace-solid-phase micro extraction (HS-SPME) for pre-concentration of PH3. Phosphine was determined with gas chromatography/pulsed flame photometric detector (PFPD). Spiked samples were used for calculation of phosphine residue in grain. Four types of fibres (100μm-PDMS, 85μm- CAR/PDMS, 75μm-CAR/PDMS and 65μm-PDMS/DVB) were tested. The bipolar fibres (CAR/PDMS and PDMS/DVB) can extract PH3, but the non-polar fibre (PDMS) did not. Larger size fibres extracted PH3 more efficiently than the smaller size fibres (e.g., 85 μm > 75 μm > 65 μm). The 85μm CAR/PDMS fibre was used to optimize the different parameters that affect the SPME extraction efficiency of PH3. In the validation study, 50 grams of wheat in a 250 mL glass flask and capped with an open-top screw cap and PTFE/Silicon septa were spiked at 0.02 ng PH3/g of wheat. The flask was then heated to 45°C in an oil bath for 45 min, after which time the 85 μm CAR/PDMS fibre was exposed for 20 min and then exposed in the heated injection port of a GC/PFPD and desorbed for 2 min. Under conditions of the validation study, the limit of detection (LOD) or level of quantification (LOQ) was in the range of 0.005–0.01 ng PH3/g of wheat. Keywords: Fumigant, Phosphine, Residue, SPME, HS-SPM

Resource Management for Intelligent Reflecting Surface Assisted THz-MIMO Network

As the preferred frequency band for future high frequency communication, the terahertz (THz) band has at-tracted wide attention. In this paper, an energy efficient resource optimization problem in THz band is studied. The massive Multiple-Input Multiple-Output (MIMO) technology and intelligent reflecting surface (IRS) are adopted to improve the capacity and energy efficiency (EE) of proposed network. An IRS assisted THz-MIMO downlink wireless network system is established. The original EE problem is decomposed into phase-shift matrix optimization and power allocation. On this basis, a distributed EE optimization algorithm is designed, which transforms the original nonlinear problem into a convex optimization problem. The simulation results reveal that the proposed distributed optimization method converges rapidly and abtains the maximum EE. This also proves that it is feasible and effective to apply both the IRS and the massive MIMO technology into THz communication network