Magnetohydrodynamic Model of Equatorial Plasma Torus in Planetary Nebulae

Some basic structures in planetary nebulae are modeled as self-organized magnetohydrodynamic (MHD) plasma configurations with radial flow. These configurations are described by time self-similar dynamics, where space and time dependences of each physical variable are in separable form. Axisymmetric toroidal MHD plasma configuration is solved under the gravitational field of a central star of mass $M$. With an azimuthal magnetic field, this self-similar MHD model provides an equatorial structure in the form of an axisymmetric torus with nested and closed toroidal magnetic field lines. In the absence of an azimuthal magnetic field, this formulation models the basic features of bipolar planetary nebulae. The evolution function, which accounts for the time evolution of the system, has a bounded and an unbounded evolution track governed respectively by a negative and positive energy density constant $H$.Comment: 14 figure

SMDS measurements and modeling to predict performance

The authors describe a performance study of a trial switched multimegabit data service (SMDS) link (intended for inter-LAN connection) from the perspective of customers evaluating the feasibility of the link for some target applications. The goals were to take all measurements on the customer premises and to develop a methodology general enough to be used by customers to evaluate the link. The authors measured a lightly loaded system and developed a model of the SMDS connection suitable for evaluating applications via analysis or simulation. They document their methodology and present the SMDS connection delay values as well as a likely breakdown of the constituents of that delay. They used these data to create a simulation model and to simulate a simple application. In the trial configuration, where geographical distances were small, SMDS network delay was one of the notable components of end-to-end delay in the SMDS connection. However, for most packets, throughput is limited by the T1 capacity for transmitting SMDS cells, not by the SMDS network capacity

COMPLETE SOLUTION OF THE XXZ-MODEL ON FINITE RINGS. DYNAMICAL STRUCTURE FACTORS AT ZERO TEMPERATURE.

The finite size effects of the dynamical structure factors in the XXZ-model are studied in the euclidean time $(\tau)$-representation. Away from the critical momentum $p=\pi$ finite size effects turn out to be small except for the large $\tau$ limit. The large finite size effects at the critical momentum $p=\pi$ signal the emergence of infrared singularities in the spectral $(\omega)$-representation of the dynamical structure factors.Comment: PostScript file with 12 pages + 11 figures uuencoded compresse

Real space first-principles derived semiempirical pseudopotentials applied to tunneling magnetoresistance

In this letter we present a real space density functional theory (DFT) localized basis set semi-empirical pseudopotential (SEP) approach. The method is applied to iron and magnesium oxide, where bulk SEP and local spin density approximation (LSDA) band structure calculations are shown to agree within approximately 0.1 eV. Subsequently we investigate the qualitative transferability of bulk derived SEPs to Fe/MgO/Fe tunnel junctions. We find that the SEP method is particularly well suited to address the tight binding transferability problem because the transferability error at the interface can be characterized not only in orbital space (via the interface local density of states) but also in real space (via the system potential). To achieve a quantitative parameterization, we introduce the notion of ghost semi-empirical pseudopotentials extracted from the first-principles calculated Fe/MgO bonding interface. Such interface corrections are shown to be particularly necessary for barrier widths in the range of 1 nm, where interface states on opposite sides of the barrier couple effectively and play a important role in the transmission characteristics. In general the results underscore the need for separate tight binding interface and bulk parameter sets when modeling conduction through thin heterojunctions on the nanoscale.Comment: Submitted to Journal of Applied Physic

Establishment and characterization of single and triple‐agent resistant osteosarcoma cell lines

Two human osteosarcoma cell lines (MG-63 and HOS-143B) are developed into drug-resistant models using a short-term drug exposure and recovery in drug-free media. Cisplatin, doxorubicin, and methotrexate are used as single agents and in triple combination. The highest level of resistance to cisplatin is observed in MG-63/CISR8, doxorubicin in HOS-143B/DOXR8, and methotrexate in HOS-143B/MTXR8. The MG-63/TRIR8 and HOS-143B/TRIR8 tripleresistance models show lower levels of resistance to combination treatment and are not resistant to the drugs individually. Apoptosis assays suggest that the resistance in MG-63/TRIR8 isfrom cisplatin and methotrexate and not doxorubicin. In contrast, the resistance in HOS-143B/TRIR8 is from doxorubicin and methotrexate instead of cisplatin. Upregulation of P-glycoprotein is seen in all resistant models except those developed with single-agent methotrexate. However, P-glycoprotein is not causing resistance in all cell lines as the inhibitor elacridar only reverses the resistance of doxorubicin on MG-63/ DOXR8 and HOS-143B/TRIR8. The migration of the MG-63 resistant models is significantly increased, their invasion rate tends to increase, and RT-PCR shows a switch from epithelial to mesenchymal gene signaling. In contrast, a significant decrease in migration is seen in HOS-143B resistant models with their invasion rate tending to decrease and a switch from mesenchymal to epithelial gene signaling

The Accumulation of Heavy Metals in Hydrostemma Motleyi Hook. f. Mabberlay and Hydrilla verticillata Casp.

The uptake of heavy metals (copper, zinc, nickel, cadmium and chromium) by Hydrostemma motleyi (Hook.f') Mobberlay and Hydrilla Verticillata Gasp. was studied. The uptake generally increased with increasing metal concentrations. The enrichment factor which relates the metal content in plants to the metal content in cultivation media generally decreased with increasing metal concentrations. Antagonistic action was observed when Hydrostemma motleyi was cultivated in mixed solutions of copper, zinc and nickel. For Hydrilla verticillata, synergistic effect was observed at low concentration of the mixed solution, but at higher concentrations, the effect was reversed. Metal accumulation appears to be species specific. Hydrilla verticillata exhibited a higher tolerance and accumulation capacity for heavy metals than Hydrostemma motleyi. It has the potential of being an indicator species for metal pollution in water

Ballistic-Ohmic quantum Hall plateau transition in graphene pn junction

Recent quantum Hall experiments conducted on disordered graphene pn junction provide evidence that the junction resistance could be described by a simple Ohmic sum of the n and p mediums' resistances. However in the ballistic limit, theory predicts the existence of chirality-dependent quantum Hall plateaus in a pn junction. We show that two distinctively separate processes are required for this ballistic-Ohmic plateau transition, namely (i) hole/electron Landau states equilibration and (ii) valley iso-spin dilution of the incident Landau edge state. These conclusions are obtained by a simple scattering theory argument, and confirmed numerically by performing ensembles of quantum magneto-transport calculations on a 0.1um-wide disordered graphene pn junction within the tight-binding model. The former process is achieved by pn interface roughness, where a pn interface disorder with a root-mean-square roughness of 10nm was found to suffice under typical experimental conditions. The latter process is mediated by extrinsic edge roughness for an armchair edge ribbon and by intrinsic localized intervalley scattering centers at the edge of the pn interface for a zigzag ribbon. In light of these results, we also examine why higher Ohmic type plateaus are less likely to be observable in experiments.Comment: 9 pages, 6 figure

Relationship between leadership style and performance of Perak SUKMA athletes and coaches

The purpose of this study was to examine the relationship between leadership style and performance of athletes and coaches in Malaysia. One hundred and thirty seven athletes and 47 coaches from 12 sports participated in the study. Leadership Scale for Sport (LSS) questionnaire was utilized to assessed athletes’ preference, perceived and coaches’ perception of their own leadership style. Result showed athletes most preferred coaching styles were training and instruction followed by democratic, positive feedback and social support. Autocratic behaviour was the least preferred. However coaches’ self-evaluation showed majority were keen on autocratic leadership style. Overall, the results of the study proposed that coaches should emphasis on training and instruction and less autocratic leadership style. Coaches also need to practise more positive feedback which proven can enhance athletes performance.Key word: Leadership style, sports performance, coach, athletes