Exotic radiation from a photonic crystal excited by an ultra-relativistic electron beam

We report the observation of an exotic radiation (unconventional Smith-Purcell radiation) from a one-dimensional photonic crystal. The physical origin of the exotic radiation is direct excitation of the photonic bands by an ultra-relativistic electron beam. The spectrum of the exotic radiation follows photonic bands of a certain parity, in striking contrast to the conventional Smith-Purcell radiation, which shows solely a linear dispersion. Key ingredients for the observation are the facts that the electron beam is in an ultra-relativistic region and that the photonic crystal is finite. The origin of the radiation was identified by comparison of experimental and theoretical results.Comment: 4 pages, 5 figure

Gravitational diffraction radiation

We show that if the visible universe is a membrane embedded in a higher-dimensional space, particles in uniform motion radiate gravitational waves because of spacetime lumpiness. This phenomenon is analogous to the electromagnetic diffraction radiation of a charge moving near to a metallic grating. In the gravitational case, the role of the metallic grating is played by the inhomogeneities of the extra-dimensional space, such as a hidden brane. We derive a general formula for gravitational diffraction radiation and apply it to a higher-dimensional scenario with flat compact extra dimensions. Gravitational diffraction radiation may carry away a significant portion of the particle's initial energy. This allows to set stringent limits on the scale of brane perturbations. Physical effects of gravitational diffraction radiation are briefly discussed.Comment: 5 pages, 2 figures, RevTeX4. v2: References added. Version to appear in Phys. Rev.

Shannon dimensionality of quantum channels and its application to photon entanglement

We introduce the concept of Shannon dimensionality D as a new way to quantify bipartite entanglement as measured in an experiment. This is applied to orbital-angular-momentum entanglement of two photons, using two state analyzers composed of a rotatable angular-sector phase plate that is lens-coupled to a single-mode fiber. We can deduce the value of D directly from the observed two-photon coincidence fringe. In our experiment, D varies between 2 and 6, depending on the experimental conditions. We predict how the Shannon dimensionality evolves when the number of angular sectors imprinted in the phase plate is increased and anticipate that D = 50 is experimentally within reach.Comment: 4 pages, 3 figures, accepted for Physical Review Letter

Festival and Organization Studies

The present essay examines the festival as a form of organizing and as a metaphor for contemporary organizations. Drawing upon classical and contemporary perspectives on festival, we focus on social ambivalences and how these are enacted and mediated through festivals. Specifically, we argue that festivals mark a tension between linear and cyclical dimensions of social time. Next, we argue that formal institutional and communitarian principles are mediated through festival. Finally, we argue that festivals mark a tension between reflexivity and social critique on the one hand and mass spectacle on the other, and problematize the notion of bodily enjoyment as a form of social consciousness. We discuss the implications of these three ambivalences \u2013 in the notion of time, the notion of community and the notion of reflexivity \u2013 for contributing to contemporary organizational discussions

Temporary Acceleration of Electrons While Inside an Intense Electromagnetic Pulse

A free electron can temporarily gain a very significant amount of energy if it is overrun by an intense electromagnetic wave. In principle, this process would permit large enhancements in the center-of-mass energy of electron-electron, electron-positron and electron-photon interactions if these take place in the presence of an intense laser beam. Practical considerations severely limit the utility of this concept for contemporary lasers incident on relativistic electrons. A more accessible laboratory phenomenon is electron-positron production via an intense laser beam incident on a gas. Intense electromagnetic pulses of astrophysical origin can lead to very energetic photons via bremsstrahlung of temporarily accelerated electrons

Tensor variational inequalities: Theoretical results, numerical methods and applications to an economic equilibrium model

The paper deals with the study of tensor variational inequalities. and some projection methods to solve them. In particular, some properties on the solutions to such an inequality are established and a fixed point theorem is proved. Moreover, some numerical methods are introduced and the convergence analysis of them is investigated. All the theoretical results are applied to analyze a general oligopolistic market equilibrium problem in which each firm produces several commodities and has some production excesses since the equilibrium condition is characterized by means of a tensor variational inequality. A numerical example is also discussed

The great denial of the monstrous in organization theory

When we began this review of The monstrous organization, we encountered an uncommon reading of organizational theory and life, populated by monsters, fantastical creatures and deviant bodies. The novel account of Thanem\u2019s Monstrous organizational theory caused us to reflect as we approached this text. The according of relevance to monstrosity has not aroused the same curiosity in Western authors, with certain fields of studies allocating greater prominence to monsters and Monstrous aspects of life than others. The guiding question for our analysis was inspired by this disparity: why, within Western culture, do images of monstrosity abound in literature, paintings, architecture, and cinema, whilst scant interest has been directed towards Monstrous bodies and creatures in organizational theory and management studies

Mathematical modelling and numerical bifurcation analysis of inbreeding and interdisciplinarity dynamics in academia

We address a mathematical model to approximate in a coarse qualitative the interaction between inbreeding-lobbying and interdisciplinarity in academia and perform a one and two-parameter numerical bifurcation analysis to analyse its dynamics. Disciplinary diversity is a necessary condition for the development of interdisciplinarity, which is being recognized today as the key to establish a vibrant academic environment with bigger potential for breakthroughs/innovation in research and technology. However, the interaction of several factors including institutional policies, and behavioural attitudes put significant barriers on advancing interdisciplinarity. A “cognitive rigidity” may rise due to reactive academic lobby behaviours favouring inbreeding. The proposed model consists of four coupled non-linear Ordinary Differential Equations simulating the interaction between certain types of academic behaviour and the rate of knowledge advancement which is related to the level of disciplinary diversity. The effect of a control policy that inhibits inbreeding-lobbying is also investigated. The numerical bifurcation analysis reveals a rich nonlinear behaviour including multistability, sustained oscillations, limit points of limit cycles, homoclinic bifurcations as well as codimension-two bifurcations and in particular Bogdanov–Takens and Bautin bifurcations

Crafting social memory for international recognition: the role of place and tradition in an Italian silk-tie maker

This chapter focuses on the role of place and local history in building the brand identities of craft organizations. Recent research on craft organizations has focused on the local context as an important factor for identity recognition and distinctiveness. However, an important but understudied aspect of this relates to the organizational use of both the sense of place and history and how visions of the past are used to support and legitimate organizational operations. In this context, local history is not simply regarded as a timeline along which events come to pass, but as a symbolic and cultural artefact that organizational actors deliberately manage and construct

Produzioni di eccellenza: un caso di successo

In questo capitolo si presenta il caso di un produttore di cravatte artigianali che è stato in grado di valo-rizzare la storia e il background di partenza, e se ne evidenziano le implicazioni principali, sottolineando l’importanza della memoria come asset strategico per la formazione di un’identità organizzativa. Questo capitolo si concentra dunque su un produttore artigianale di cravatte localizzato nella città di Napoli: E. Marinella. Il caso è stato scelto in quanto rappresenta ai nostri occhi un esempio virtuoso di valorizzazione della tradizione locale e della propria storia aziendale. Grazie alla valorizzazione della propria tradizione E. Marinella è riuscita infatti a posizionarsi come un marchio di lusso, apprezzato per la manifattura artigianale e l’unicità della propria collezione