Phase diagram of an Ising model with long-range frustrating interactions: a theoretical analysis

We present a theoretical study of the phase diagram of a frustrated Ising model with nearest-neighbor ferromagnetic interactions and long-range (Coulombic) antiferromagnetic interactions. For nonzero frustration, long-range ferromagnetic order is forbidden, and the ground-state of the system consists of phases characterized by periodically modulated structures. At finite temperatures, the phase diagram is calculated within the mean-field approximation. Below the transition line that separates the disordered and the ordered phases, the frustration-temperature phase diagram displays an infinite number of ``flowers'', each flower being made by an infinite number of modulated phases generated by structure combination branching processes. The specificities introduced by the long-range nature of the frustrating interaction and the limitation of the mean-field approach are finally discussed.Comment: 32 pages, 7 figure

Heterogeneous space-division multiplexing and joint wavelength switching demonstration

We demonstrate a six spatial-mode, wavelength-routing network interoperable with few-mode, coupled-multi-core, and single-mode fiber spans using a custom 57-port wavelength-selective switch configured for joint-switching of spatial-superchannels

New Faces and New Masks of Today's Consumer

In 1995, we proposed that consumption and contemporary consumerism could not be studied or understood separately from the world of work and production. We proposed that contemporary consumerism was built on the back of what we referred to as `the Fordist Deal'. This deal, pioneered by Henry Ford for his employees, was the promise of ever increasing standards of living in exchange for a quiescent labour force accepting alienating work. Since that deal was struck, consumerism came to signify a general pre-occupation with consumption standards and choice as well as a willingness to read meanings in material commodities and to equate happiness and success with material possessions. In this sense, Ford may be seen as the father both of mass production and mass consumption. Since the Fordist high noon of consumerism in the West, mass consumption is widely seen as having fragmented into a proliferation of highly individualized niche products. For its part, a considerable part of mass production has migrated to countries with lower wages and looser environmental and social controls, fueling their own variants of consumerism. In this article, we examine the gradual erosion of the Fordist Deal in the light of developments in the last 10 years or so, seeking to assess the future of consumerism at a global level. We also seek to identify and discuss some emerging conceptualizations of the consumer, some of the new faces and masks assumed by the archetypal character of our types. We analyse some of the tensions and contradictions lurking behind these conceptualizations and try to envisage some of the real choices facing consumers today and some of the processes of social change that hinge on the outcomes of these choices. The article identifies a fundamental paradox between the ubiquity of the consumer in contemporary discourses and the virtual impossibility of generalizing about consumers. We suggest, then, that the consumer may be viewed as one of those `essentially contested concepts' proposed by Gallie that defy domestication. The consumer, we argue, is unmanageable, both as a concept, since no-one can pin it down to one specific conceptualization at the expense of all others, and as an entity, since attempts to control and manage the consumer lead to the consumer mutating from one impersonation to another. It is precisely this paradox that we seek to capture in our article's title. The article concludes with a consideration of three basic challenges that are liable to lead to fundamental reorientation of consumption and production, as well as of our conceptualizations and theorizing about them. These challenges are the outcomes of environmental, demographic and social factors that, we argue, make the current situation unsustainable and will bring about its dissolution

Phonon driven transport in amorphous semiconductors: Transition probabilities

Inspired by Holstein's work on small polaron hopping, the evolution equations of localized states and extended states in presence of atomic vibrations are derived for an amorphous semiconductor. The transition probabilities are obtained for four types of transitions: from one localized state to another localized state, from a localized state to an extended state, from an extended state to a localized state, and from one extended state to another extended state. At a temperature not too low, any process involving localized state is activated. The computed mobility of the transitions between localized states agrees with the observed `hopping mobility'. We suggest that the observed `drift mobility' originates from the transitions from localized states to extended states. Analysis of the transition probability from an extended state to a localized state suggests that there exists a short-lifetime belt of extended states inside conduction band or valence band. It agrees with the fact that photoluminescence lifetime decreases with frequency in a-Si/SiO$_{2}$ quantum well while photoluminescence lifetime is not sensitive to frequency in c-Si/SiO$_{2}$ structure.Comment: 41 pages, 3 figures, submitted to Phys. Rev.

Nanoparticles for Applications in Cellular Imaging

In the following review we discuss several types of nanoparticles (such as TiO2, quantum dots, and gold nanoparticles) and their impact on the ability to image biological components in fixed cells. The review also discusses factors influencing nanoparticle imaging and uptake in live cells in vitro. Due to their unique size-dependent properties nanoparticles offer numerous advantages over traditional dyes and proteins. For example, the photostability, narrow emission peak, and ability to rationally modify both the size and surface chemistry of Quantum Dots allow for simultaneous analyses of multiple targets within the same cell. On the other hand, the surface characteristics of nanometer sized TiO2allow efficient conjugation to nucleic acids which enables their retention in specific subcellular compartments. We discuss cellular uptake mechanisms for the internalization of nanoparticles and studies showing the influence of nanoparticle size and charge and the cell type targeted on nanoparticle uptake. The predominant nanoparticle uptake mechanisms include clathrin-dependent mechanisms, macropinocytosis, and phagocytosis

Gendering the careers of young professionals: some early findings from a longitudinal study. in Organizing/theorizing: developments in organization theory and practice

Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce – not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales