Optical absorption spectra in fullerenes C60 and C70: Effects of Coulomb interactions, lattice fluctuations, and anisotropy

Effects of Coulomb interactions and lattice fluctuations in the optical absorption spectra of C60 and C70 are theoretically investigated by using a tight binding model with long-range Coulomb interaction and bond disorder. Anisotropy effects in C70 are also considered. Optical spectra are calculated by using the Hartree-Fock approximation followed by the configuration interaction method. The main conclusions are as follows: (1) The broad peaks at excitation energies, 3.7eV, 4.7eV, and 5.7eV, observed in experiments of C60 molecules in a solution are reasonably described by the present theory. Peak positions and relative oscillator strengths are in overall agreement with the experiments. The broadening of peaks by lattice fluctuations is well simulated by the bond disorder model. (2) The optical gap of C70 is larger when the electric field of light is parallel to the long axis of the molecule. The shape of the frequency dispersion also depends on the orientation of the molecule. These properties are common in the free electron model and the model with Coulomb interactions. (3) The spectrum of C70 averaged over bond disorder and random orientations is compared with experiments in a solution. There is an overall agreement about the spectral shape. Differences in the spectra of C60 and C70 are discussed in connection with the symmetry reduction from a soccerball to a rugbyball.Comment: PACS numbers: 78.66.Qn, 78.20.Dj, 71.35.+z, 31.20.Tz; LaTeX, 15 pages, 5 figures (Physical Review B); Note: Please request figures to Authors. They will be sent via snail mai

Stabilization of the Plate Current in Vacuum Tube Power Amplifier Using Cathode Resistor

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Optical absorption spectra of A6C60 and A6C70: Reduction of effective Coulomb interactions in Frenkel excitons

We theoretically investigate optical absorption spectra of \soc^{6-} and \rug^{6-}, and discuss relations with the optical properties of alkali metal doped fullerides A_6\soc and A_6\rug. This is a valid approach for systems where Frenkel exciton effects are dominant. We use a tight binding model with long ranged Coulomb interactions and bond disorder. Optical spectra are obtained by the Hartree-Fock approximation and the configuration interaction method. We find that the Coulomb interaction parameters, which are relevant to the optical spectra of A_6\soc (A_6\rug) in order to explain the excitation energies and relative oscillator strengths of absorption peaks, are almost the half of those of the neutral \soc (\rug). The reduction of the effective Coulomb interactions is concluded for the heavily doped case of \soc and \rug. This finding is closely related with the experimental fact that dielectric constants of fullerides which are maximumly doped with alkali metals become about twice as large as those of the neutral systems.Comment: Note: A full preprint with figures should be requested to the author. It will be sent by air-mail.; E-mail: [email protected]

Inferring tumor progression from genomic heterogeneity

Cancer progression in humans is difficult to infer because we do not routinely sample patients at multiple stages of their disease. However, heterogeneous breast tumors provide a unique opportunity to study human tumor progression because they still contain evidence of early and intermediate subpopulations in the form of the phylogenetic relationships. We have developed a method we call Sector-Ploidy-Profiling (SPP) to study the clonal composition of breast tumors. SPP involves macro-dissecting tumors, flow-sorting genomic subpopulations by DNA content, and profiling genomes using comparative genomic hybridization (CGH). Breast carcinomas display two classes of genomic structural variation: (1) monogenomic and (2) polygenomic. Monogenomic tumors appear to contain a single major clonal subpopulation with a highly stable chromosome structure. Polygenomic tumors contain multiple clonal tumor subpopulations, which may occupy the same sectors, or separate anatomic locations. In polygenomic tumors, we show that heterogeneity can be ascribed to a few clonal subpopulations, rather than a series of gradual intermediates. By comparing multiple subpopulations from different anatomic locations, we have inferred pathways of cancer progression and the organization of tumor growth. © 2010 by Cold Spring Harbor Laboratory Press

The Asylum-Seeker and Refugee Experience - An Interpretative Phenomenological Analysis of Interview Data Elicited Through the Use of Artefacts

Theme 3: Protection of the ‘most vulnerable’ - children, young people growing up in ‘austerity’ older people, migrants Background: There is a pressing need to understand the experiences of those who undertake forced migration. The UNHCR (2016) has reported that “one in every 113 people globally is now either an asylum-seeker, internally displaced or a refugee” - this is at its highest level since the Second World War. Aims: This study sought to explore the lived experiences of asylum-seekers and refugees based in the United Kingdom in an effort to understand the psycho-social challenges and support systems in place for them. Methods: This was a qualitative study. 11 participants were interviewed on two separate occasions. In the first interview, each participant was asked to bring an artefact of something that was personal to them and best represented their life experiences. The second interview allowed for further exploration of issues that arose from the first interview and also enabled rapport to be developed in an effort to elicit a deeper level understanding of the lived experience of being an asylum-seeker or refugee from conversations in the second interview. Findings: Findings to be reported in this presentation will show themes related to: meaning-making, offering and receiving collective support, and the potential for growth via connections with spiritual communities. Conclusions: A detailed analysis of these personal accounts from this sample of asylum-seekers and refugees could help inform an understanding and appropriate intervention planning on a local, national, and global level when aiming to address the psycho-social and spiritual needs of this target group. Mainstreaming community psychology interventions: reflections on workin

Poverty and 'Second Economy' in South Africa: An Attempt to Clarify Applicable Concepts and Quantify Extent of Relevant Challenges

In brief, the paper firstly summarises old and new theoretical and technical issues on measuring poverty, secondly analyses poverty from different perspectives and highlights various research findings on poverty trends in South Africa and thirdly clarifies the notion of "second economy" and attempts to "measure" it

Cloud computing and RESERVOIR project

The support for complex services delivery is becoming a key point in current internet technology. Current trends in internet applications are characterized by on demand delivery of ever growing amounts of content. The future internet of services will have to deliver content intensive applications to users with quality of service and security guarantees. This paper describes the RESERVOIR project and the challenge of a reliable and effective delivery of services as utilities in a commercial scenario. It starts by analyzing the needs of a future infrastructure provider and introducing the key concept of a service oriented architecture that combines virtualisation-aware grid with grid-aware virtualisation, while being driven by business service management. This article will then focus on the benefits and the innovations derived from the RESERVOIR approach. Eventually, a high level view of RESERVOIR general architecture is illustrated

Performing the repentant lover in the courtroom: An analysis of Oscar Pistorius’ recreation of hegemonic masculinity

Michel Foucault (1980) presented social theorists with a consideration of power as existing everywhere. Furthermore, Jonathan Heaney (J Polit Power 6:355–362, 2013) recently asserted that emotions and power should be considered conceptual counterparts. I propose that what Foucault referred in terms of the omnipresence of power refers to its deeply social connection to emotions. One emotion, in particular, romantic love, has captured the sociological imagination not only at the level of personal relationships but also in connection with capitalism, as an ideology spurring consumption and influencing the construction of discourses and places. This chapter presents an analysis of the trial of Oscar Pistorius and the analysis plays on two levels: (a) firstly, through his courtroom interactions with members of the defence, and (b) through my eyes as a viewer, witnessing the trial on television. The televised South African courtroom becomes a space for the portrayal of a power-suffused masculine identity, which is emotionally constituted through emotional control and emotional release