Decoherence in quantum dots due to real and virtual transitions: a non-perturbative calculation

We investigate theoretically acoustic phonon induced decoherence in quantum dots. We calculate the dephasing of fundamental (interband or intraband) optical transitions due to real and virtual transitions with higher energy levels. Up to two acoustic phonon processes (absorption and/or emission) are taken into account simultaneously in a non-perturbative manner. An analytic expression of acoustic phonon induced broadening is given as a function of the electron-phonon matrix elements and is physically interpreted. The theory is applied to the dephasing of intersublevel transitions in self-assembled quantum dots.Comment: 8 pages, 4 figure

Revisiting the Naturalness Problem -- Who is afraid of quadratic divergences? --

It is widely believed that quadratic divergences severely restrict natural constructions of particle physics models beyond the standard model (SM). Supersymmetry provides a beautiful solution, but the recent LHC experiments have excluded large parameter regions of supersymmetric extensions of the SM. It will now be important to reconsider whether we have been misinterpreting the quadratic divergences in field theories. In this paper, we revisit the problem from the viewpoint of the Wilsonian renormalization group and argue that quadratic divergences, which can always be absorbed into a position of the critical surface, should be simply subtracted in model constructions. Such a picture gives another justification to the argument that the scale invariance of the SM, except for the soft-breaking terms, is an alternative solution to the naturalness problem. It also largely broadens possibilities of model constructions beyond the SM since we just need to take care of logarithmic divergences, which cause mixings of various physical scales and runnings of couplings.Comment: 22 pages, 6 figures, version published in Phys. Rev.

Growth Mechanism of Helicoidal Nickel Whiskers

NICKEL whiskers obtained by reduction of the iodide of the metal can be classified into two categories : (i) rectilinear whiskers (ii) helicoidal whiskers In general, these whiskers are formed by a stacking of small idiomorphic crystals. The law governing such stackings was determined theoretically in a previous investigation .1,2 It was shown that they were formed from nickel iodide in fusion and that the theory of dendritic growth was quite true for rectilinear whiskers ; the axes of growth are of low indices ( , ---100> ) and the conditions required for dendritic growth as described by Papapetrou3 are fulfilled. Rectilinear whiskers without branches are obtained, because one of the directions of dendritic growth is favoured and the development takes place only in that direction. This paper presents a study of the growth mechanisms of helicoidal whiskers

Growth Mechanism of Helicoidal Nickel Whiskers

Nickel whiskers obtained by reduction of the iodide of the metal can be classified into two categories:- - Rectilinear whiskers - Spiral whiskers Rectilinear whiskers without branches are obtained because one of the directions of dendritic growth is favoured and the development takes place only in that direction

Think Piece. Learning of Environment(s) and Environment(s) of Learning

As we reflect on the 30 years that have passed since the first intergovernmental conference on environmental education that was held in Tbilisi, Georgia, it might be useful to review how learning of environment(s) has changed over time and also how environment(s) of learning have changed. And also, what challenges these changes present for contemporary societies. The Tbilisi conference took place at a crucial time in human history, following sharpened awareness in the 1960s of human activity impacting negatively on natural systems. But, also a time when humans were still optimistic that environmental destruction could be reversed and that education might play a role in achieving it. What transpired at the conference might therefore be understood as a meeting where representatives of governments proactively defined objectives, goals and principles for guiding environmental education activities, in view of an impending socio-ecological crisis (at the time) (UNESCO-UNEP, 1978). The focus of this short essay is on learning, therefore we first draw attention to some of the Tbilisi Principles pertinent to learning of environments and environments of learning. The first Tbilisi Principle suggests that environmental education should consider the environment in its totality, implying that learning about/in/for environments should involve all dimensions of environments and how these  dimensions interact with one another. This Principle is linked to Principle 4 which states that the approach to learning should be interdisciplinary. Furthermore, Principle 2 states that learning should be a continuous lifelong process and Principle 8 states that learners should be active participants in planning their own learning experiences, and that they should make their own decisions as well as take responsibility for their decisions

Efficacy of using life design-based counselling for an emerging adult who had suffered parental neglect

This article reports on the value of life design-based counselling for an emerging adult who had experienced parental (emotional) neglect and was now ready to embark on a career. Purposive sampling was used to select an emerging adult who had experienced parental neglect and had entered the workplace stage. Such research in South African education contexts is limited. A QUAL + quan design was used to gather and analyse the data. An intrinsic, descriptive, exploratory intervention case study involving a single individual was the basis of the research. Thematic data analysis (in combination with ATLAS.ti) was conducted to analyse the data, that is, look for themes and subthemes in the data. The intervention enhanced the participant’s career resilience and career adaptability. Exploring her life story for themes and patterns helped her gain new insight into the meaning of her experiences. The intervention enabled her to enter a new chapter in her life from a position of strength and an improved sense of self. Longitudinal studies on the long-term effects of life design-based interventions on groups of emerging adults who had experienced different kinds of parental neglect are needed to determine the longer-term value of the kind of intervention described in this article

A Web/Grid Services Approach for Integration of Virtual Clinical & Research Environments

Clinicans have responsibilities for audit and research, often participating in projects with basic scientist colleagues. Our work in a regional teaching hospital setting involves collaboration with the medical school computer services and builds upon work developed in computer science department as part of the Collaborative Orthopaedic Research Environment (CORE) project[1]. This has established a pilot study for proof of concept work. Users are mapped to a personal profile implemented using XML and a service oriented architecture (SOA)[2,3]. This bridges the e-Health and e-Science domains, addressing some of the basic questions of security and uptake