The Holographic Interpretation of Hawking Radiation

Holography gives us a tool to view the Hawking effect from a new, classical perspective. In the context of Randall-Sundrum braneworld models, we show that the basic features of four-dimensional evaporating solutions are nicely translated into classical five-dimensional language. This includes the dual bulk description of particles tunneling through the horizon.Comment: 10 pages, 1 figure, Honorable Mention in the Gravity Research Foundation Essay Competition 200

The three-body recombination of a condensed Bose gas near a Feshbach resonance

In this paper, we study the three-body recombination rate of a homogeneous dilute Bose gas with a Feshbach resonance at zero temperature. The ground state and excitations of this system are obtained. The three-body recombination in the ground state is due to the break-up of an atom pair in the quantum depletion and the formation of a molecule by an atom from the broken pair and an atom from the condensate. The rate of this process is in good agreement with the experiment on $^{23}$Na in a wide range of magnetic fields.Comment: 10 pages, 2 figures, to be published in Phys. Rev.

Managing the mining cycle using GeoVisionary

Managing the mining cycle from exploration through to evaluation, planning, construction, operation and finally mine closure can involve many datasets in different formats. To be able to visualise all of these different datasets in one environment is important to locate mineral/ore deposits, moderate risks, increase mining efficiency, monitor the impact on the surrounding environment and communicate these factors to stakeholders. Typically, GIS – Geographical Information Systems have been used to manage the life cycle of a mine, however the three dimensional (3D) complexity is lost in these two dimensional (2D) systems. Virtalis alongside the British Geological Survey, have developed the GeoVisionary software which provides the means to aid the management of many aspects of the life cycle of a mine using a combination 2D, 3D and 4D data in the same virtual environment

A 20 GHz bright sample for {\delta} > +72{\deg}: I. Catalogue

During 2010-2011, the Medicina 32-m dish hosted the 7-feed 18-26.5 GHz receiver built for the Sardinia Radio Telescope, with the goal to perform its commissioning. This opportunity was exploited to carry out a pilot survey at 20 GHz over the area for {\delta} > + 72.3{\deg}. This paper describes all the phases of the observations, as they were performed using new hardware and software facilities. The map-making and source extraction procedures are illustrated. A customised data reduction tool was used during the follow-up phase, which produced a list of 73 confirmed sources down to a flux density of 115 mJy. The resulting catalogue, here presented, is complete above 200 mJy. Source counts are in agreement with those provided by the AT20G survey. This pilot activity paves the way to a larger project, the K-band Northern Wide Survey (KNoWS), whose final aim is to survey the whole Northern Hemisphere down to a flux limit of 50 mJy (5{\sigma}).Comment: 10 pages, 10 figures. Accepted by MNRA

Two-dimensional Quantum Black Holes, Branes in BTZ and Holography

We solve semiclassical Einstein equations in two dimensions with a massive source and we find a static, thermodynamically stable, quantum black hole solution in the Hartle-Hawking vacuum state. We then study the black hole geometry generated by a boundary mass sitting on a non-zero tension 1-brane embedded in a three-dimensional BTZ black hole. We show that the two geometries coincide and we extract, using holographic relations, information about the CFT living on the 1-brane. Finally, we show that the quantum black hole has the same temperature of the bulk BTZ, as expected from the holographic principle.Comment: 10 pages, 2 figures, RevTex, ``point particle of mass \mu '' changed with ``massive boundary source'' for better clarity. Action in (50) written in Z_2 symmetric form. Appendix clarified. Minor corrections and references added. Version accepted for pubblication in PRD15 (2006

Casimir-like tunneling-induced electronic forces

We study the quantum forces that act between two nearby conductors due to electronic tunneling. We derive an expression for these forces by calculating the flux of momentum arising from the overlap of evanescent electronic fields. Our result is written in terms of the electronic reflection amplitudes of the conductors and it has the same structure as Lifshitz's formula for the electromagnetically mediated Casimir forces. We evaluate the tunneling force between two semiinfinite conductors and between two thin films separated by an insulating gap. We discuss some applications of our results.Comment: 8 pages, 3 figs, submitted to Proc. of QFEXT'05, to be published in J. Phys.

Multiphysics analyses of the effect of package on the performances of PMUT transducers

The paper deals with the multiphysics modeling of piezoelectric micromachined ultrasound transducers (PMUT), that can be used in several practical applications. The model accounts for the multiple couplings between the mechanical fields and the electric and acoustic ones. The numerical solution has been sought by means of the finite element method, for the special case of axial symmetry. The model has been validated with reference to experimental data, that have been obtained by the Authors. The numerical procedure has been applied to carry out a parametric analysis of the effect of package, to extract a set of design guidelines

Uso de leguminosas na fitorremediação de solo contaminado com sulfentrazone.

RESUMO: Resíduos de sulfentrazone podem permanecer no solo por cerca de dois anos, oferecendo risco de contaminação a lençóis freáticos e possibilitando o cultivo de espécies susceptíveis. Diante disto, a fitorremediação pode representar uma opção para a descontaminação de áreas que sofreram com intensas aplicações deste herbicida. O presente trabalho avaliou o potencial remediador das espécies Crotalaria juncea, Canavalia ensiformis, Cajanus cajan e Cajanus cajan (anão), com relação ao herbicida sulfentrazone, utilizando-se o milheto (Pennisetum glaucum) como planta bioindicadora. O experimento foi instalado em casa-de-vegetação e os tratamentos compostos pela combinação entre as quatro espécies citadas, além da testemunha, e quatro doses de sulfentrazone (0 g i.a. ha-1, 200 g i.a. ha-1, 400 g i.a. ha-1 e 800 g i.a. ha-1). Foram avaliadas a altura de plantas, fitotoxicidade ao sulfentrazone e biomassa fresca e seca da parte aérea. Quando P. glaucum foi cultivado após C. juncea, apresentou maior ganho em biomassa e maior altura, e os sintomas de fitotoxicidade foram menos acentuados. C. juncea apresentou a maior capacidade de fitorremediar solos contaminados com sulfentrazone.ABSTRACT: Use of leguminous plants for phytoremediation of soil contaminated with sulfentrazone. Residual sulfentrazone may remain in the soil for around two years, being a source of groundwater contamination and preventing the growth of usceptible plants. So, phytoremediation may represent an option for decontaminating areas which were highly affected by applications of this herbicide. This study aimed at evaluating the potential of Crotalaria juncea, Canavalia ensiformis, Cajanus cajan and Cajanus cajan (dwarf) for remediation of soil contaminated with sulfentrazone, using millet (Pennisetum glaucum) as a bioindicator plant. The experiment was installed in a greenhouse and treatments consisted of the four species already mentioned, plus a control, and four sulfentrazone doses (0 g a.i. ha-1, 200 g a.i. ha-1, 400 g a.i. ha-1 and 800 g a.i. ha-1). Plants height, phytotoxicity to sulfentrazone and fresh and dry matter were evaluated. When P. glaucum was grown after C. juncea, the fresh and dry matter, as well as plant height, were higher, while the phytotoxicity symptoms were less evident. C. juncea showed the best results for phytoremediation of soils contaminated with sulfentrazone