A theoretical model for single molecule incoherent scanning tunneling spectroscopy

Single molecule scanning tunneling spectroscopy (STS), with dephasing due to elastic and inelastic scattering, is of some current interest. Motivated by this, we report an extended Huckel theory (EHT) based mean-field Non-equilibrium Green's function (NEGF) transport model with electron-phonon scattering treated within the self-consistent Born approximation (SCBA). Furthermore, a procedure based on EHT basis set modification is described. We use this model to study the effect of the temperature dependent dephasing, due to low lying modes in far-infrared range for which hw<<kT, on the resonant conduction through highest occupied molecular orbital (HOMO) level of a phenyl dithiol molecule sandwiched between two fcc-Au(111) contacts. Furthermore, we propose to include dephasing in room temperature molecular resonant conduction calculations.Comment: 12 pages, 5 figure

Exploring the Issues of Security, Privacy and Trust in eGovernment: UK Citizens\u27 Perspective

Recognising the potential that Information and Communications Technologies (ICTs)2 offer for competitiveness and the effectiveness of communities, Governments across the globe are striving to provide online products and services3 to all user groups. There are various definitions of e-government within the literature, and the one being applied in this research is: Egovernment is the application of technology to enable, enhance and improve access to the delivery of government services for the benefit of citizens, employees and enterprise (Silcock, 2001) Whilst there are diverse definitions of e-government, there are also variations in the classification of e-government, each dependent upon the relation between the various stakeholders. Bélanger and Hiller (2005) classified e-government into six categories: Government Delivering Services to Individuals (G2IS), Government to Individuals as a Part of the Political Process (G2IP), Government to Business as a Citizen (G2BC), Government to Business in the Marketplace (G2BMKT), Government to Employees (G2E) and Government to Government (G2G). G2IS involves communication and services between government and citizens (G2C); G2IP involves the relationship that the government has with citizens as a part of the democratic process, such as e-voting. G2BC involves organizations paying taxes or filing reports, and G2BMKT focuses on business transactions between government and businesses, such as e-procurement. Electronic interactions between Government and Citizen can also be classified as a ‘Government to Citizen’ (G2C) model of eGovernment (Beynon-Davies: 2007). This is also referred to as the ‘Transactional’ stage of eGovernment, where the interaction can occur with an agency (NAO, 2007). This interaction involves the receipt or dissemination of information, the completion or submission of a form, the sending of payments, the inspection of an account, or more complicated sets of dealings. It is such transactions that can be perceived to be of sensitive nature for citizens and users are reluctant to conduct transactions, with concerns ranging from: payment security, not understanding how to integrate information and customization impacting their privacy (Belanger & Hiller; 2005). This leads onto security and privacy and their possible effects on transactional stage adoption. In this research paper the aim is to explore how UK is dealing with the issues of security, privacy and trust when adopting and using online government products or services. This is pertinent at this time as the government is taking large steps to increase adoption and usage amongst citizens. By undertaking this research, several contributions are made: Governments around the globe, including, UK are increasingly seeking success at e-Government adoption and usage and such research assists policymakers in obtaining a better understanding. For industry, private sector organizations are partners in the provision of the infrastructure and involved in many other implementation and adoption e-Government projects and research such as this allows them to consider these factors in more depth. For academics, security, privacy and trust are issues of immense importance and research such as this allows academics to become more aware of these topics

Glue spin and helicity in proton from lattice QCD

We report the first lattice QCD calculation of the glue spin in the nucleon. The lattice calculation is carried out with valence overlap fermions on 2+1 flavor DWF gauge configurations on four lattice spacings and four volumes including an ensemble with physical values for the quark masses. The glue spin $S_{G}$ in the Coulomb gauge in the $\overline{\text{MS}}$ scheme is obtained with the 1-loop perturbative matching. We find the results fairly insensitive to lattice spacing and quark masses. We also find that the proton momentum dependence of $S_G$ in the range $0\leq |\vec{p}| < 1.5$ GeV is very mild, and we determine it in the large momentum limit to be $S_{G}=0.251(47)(16)$ at the physical pion mass in the $\overline{\text{MS}}$ scheme at $\mu^2=10$ GeV$^2$. If the matching procedure in large momentum effective theory is neglected, $S_G$ is equal to the glue helicity measured in high-energy scattering experiments.Comment: Version accepted for publication in Physical Review Letters, 4 pages, 4 figures, supplemental materials are attached after the conten

Coupled-resonator optical waveguides: Q-factor and disorder influence

Coupled resonator optical waveguides (CROW) can significantly reduce light propagation pulse velocity due to pronounced dispersion properties. A number of interesting applications have been proposed to benefit from such slow-light propagation. Unfortunately, the inevitable presence of disorder, imperfections, and a finite Q value may heavily affect the otherwise attractive properties of CROWs. We show how finite a Q factor limits the maximum attainable group delay time; the group index is limited by Q, but equally important the feasible device length is itself also limited by damping resulting from a finite Q. Adding the additional effects of disorder to this picture, limitations become even more severe due to destructive interference phenomena, eventually in the form of Anderson localization. Simple analytical considerations demonstrate that the maximum attainable delay time in CROWs is limited by the intrinsic photon lifetime of a single resonator.Comment: Accepted for Opt. Quant. Electro

Hydrothermal synthesis of lithium silicate (Li2SiO3) from waste glass: a preliminary study

Current environmental directives to conserve resources and to divert waste streams have generated significant interest in mineral recycling. In this respect, this preliminary study has demonstrated that lithium metasilicate can be prepared by hydrothermal reaction between waste container glass and lithium hydroxide solutions at 100 °C. Minor proportions of calcium hydroxide, calcite, lithium carbonate and tobermorite were also produced during the reaction. Percentage crystallinity and proportion of lithium metasilicate in the reaction product were found to increase as functions of lithium hydroxide concentration (between 1 and 4 M). This research has also shown that the lithium metasilicate phase can take up 6.4 mmol/g of Zn2+ ions after 24 h during batch sorption. Further work to optimise the yield and to appraise the antimicrobial properties of Zn2+-bearing lithium metasilicate is now warranted

Strain and field modulation in bilayer graphene band structure

Using an external electric field, one can modulate the bandgap of Bernal stacked bilayer graphene by breaking A-~B symmetry. We analyze strain effects on the bilayer graphene using the extended Huckel theory and find that reduced interlayer distance results in higher bandgap modulation, as expected. Furthermore, above about 2.5 angstrom interlayer distance, the bandgap is direct, follows a convex relation to electric field and saturates to a value determined by the interlayer distance. However, below about 2.5 angstrom, the bandgap is indirect, the trend becomes concave and a threshold electric field is observed, which also depends on the stacking distance.Comment: 3 pages, 5 figures - v1 and v2 are the same, uploaded twice - v3, some typos fixed and a reference adde