Optical properties of charged quantum dots doped with a single magnetic impurity

We present a microscopic theory of the optical properties of self-assembled quantum dots doped with a single magnetic manganese (Mn) impurity and containing a controlled number of electrons. The single-particle electron and heavy-hole electronic shells are described by two-dimensional harmonic oscillators. The electron-electron, electron-hole Coulomb as well as the short-range electron spin-Mn spin and hole spin-Mn spin contact exchange interactions are included. The electronic states of the photo-excited electron-hole-Mn complex and of the final electron-Mn complex are expanded in a finite number of configurations and the full interacting Hamiltonian is diagonalized numerically. The emission spectrum is predicted as a function of photon energy for a given number of electrons and different number of confined electronic quantum dot shells. We show how emission spectra allow to identify the number of electronic shells, the number of electrons populating these shells and, most importantly, their spin. We show that electrons not interacting directly with the spin of Mn ion do so via electron-electron interactions. This indirect interaction is a strong effect even when Mn impurity is away from the quantum dot center.Comment: 12 pages, 10 figure

Towards an RFID microsystem for surgical instrument detection using millimeter waves

Misplacement of surgical instruments inside an operating room is a frequent mistake that can bring unnecessary complications. We propose a system that can prevent these, through wireless communication. In this paper, we investigate the use of the 55-60 GHz band in the implementation of a RFID system that presents very interesting characteristics like improved security and small size. From the measurements already made, it's expected the RFID system operating in the 60 GHz ISM will work at distances, at least, up to 5 meters. Furthermore, it is proposed a solution to obtain a fully integrated system based on an on-chip antenna that could be integrated with an RF CMOS chip based on 65 nm CMOS technology.info:eu-repo/semantics/publishedVersio

Între programul de arhitectură și frumos

Utility and beauty are two architectural design foundation stones. Over time, architecture has developed multiple combinations and interpretations of these two elements. Despite all the contextual and cultural changes, which may differentiate distinct designs, the architectural practice can be delineate as laying at the contextual root, rather than providing a direct response to procedure and standards. The overall practice of architecture embraces a synthesis of a wide range of elements interpreted in different perspectives throughout history. The practice shapes specific responses transforming and adapting places, spaces, techniques and materials to different contexts. The investigation is part of an ongoing process centered on themes and issues related to architectural design. The research guideline focusses on the What and How of architectural design. In the present paper the topics arise from a text of Álvaro Siza: „Beauty, the absolute condition of functionality” (Siza, 2018). From Álvaro Siza statement beauty and function are considered inseparable in building good architecture synthesis. The paper explores the relation between the architectural program and beauty. Frequently these two components are considered incompatible and opposite, although other perspectives ought to be explored.The dialectic overlap and boundaries between the architectural program and beauty will be inquired. The perspective allows identifying operative relations, far from the notion of contradiction or opposition. The investigation context is grounded in the universe of architectural design. On one side it can be found beauty, characterised by an idealistic desire for perfection and truth. We are dealing with an immaterial universe. On the other, the architectural program stands for the architectural practical and useful attributes of use. Through a holistic methodology it is expected an operative input to architectural design practice. In the same direction we hope to contribute for the enlargement of the range of level of self-reflective practice

Arp2/3 complex activity in filopodia of spreading cells

Background Cells use filopodia to explore their environment and to form new adhesion contacts for motility and spreading. The Arp2/3 complex has been implicated in lamellipodial actin assembly as a major nucleator of new actin filaments in branched networks. The interplay between filopodial and lamellipodial protrusions is an area of much interest as it is thought to be a key determinant of how cells make motility choices. Results We find that Arp2/3 complex localises to dynamic puncta in filopodia as well as lamellipodia of spreading cells. Arp2/3 complex spots do not appear to depend on local adhesion or on microtubules for their localisation but their inclusion in filopodia or lamellipodia depends on the activity of the small GTPase Rac1. Arp2/3 complex spots in filopodia are capable of incorporating monomeric actin, suggesting the presence of available filament barbed ends for polymerisation. Arp2/3 complex in filopodia co-localises with lamellipodial proteins such as capping protein and cortactin. The dynamics of Arp2/3 complex puncta suggests that they are moving bi-directionally along the length of filopodia and that they may be regions of lamellipodial activity within the filopodia. Conclusion We suggest that filopodia of spreading cells have regions of lamellipodial activity and that this activity affects the morphology and movement of filopodia. Our work has implications for how we understand the interplay between lamellipodia and filopodia and for how actin networks are generated spatially in cells

Effective action in DSR1 quantum field theory

We present the one-loop effective action of a quantum scalar field with DSR1 space-time symmetry as a sum over field modes. The effective action has real and imaginary parts and manifest charge conjugation asymmetry, which provides an alternative theoretical setting to the study of the particle-antiparticle asymmetry in nature.Comment: 8 page

Performance assessment of wireless power transfer links for implantable microsystems

Wireless power transfer is a hot topic due to the growth of implanted device solutions which, as they get smaller and smarter, demand new solutions to power them up. These solutions need to keep the power level, namely SAR (specific absorption ratio) below a determined safety standard and to allow the device to be as small as possible. Current fabrication techniques allow the creation of ultra-small 3D antennas integrated on silicon wafers, which can lead to the miniaturization of implantable devices due to the possible reduction or even elimination of battery size. To evaluate this possibility, the antenna must be tested in conditions close to real working conditions, requiring the use of human body phantoms. This paper proposes a solution to measure the power received by an ultra-small antenna placed inside a phantom, without the use of coaxial cables attached to the device. Instead, an optoelectronic mechanism is used to route the received power to an optical fiber, and an optical spectrum analyzer is used to measure the received power.This work was supported by Portuguese Foundation for Science and Technology: FCT-PTDC/EEI-TEL/2881/2012, Programa Operacional Temático Fatores de Competitividade (COMPETE) and Fundo Comunitário Europeu FEDER.info:eu-repo/semantics/publishedVersio

“The closed door?” The relationship of the Ciganos with the labour market from the perspective of the employment and training officers

The employability of the Portuguese Roma, or Ciganos, is one of the major challenges that arises in contemporary Portuguese society, being transversal to other European countries, since a part of this population lack the necessary school and professional qualifications for their integration in the labour market. Employment and professional training centres can operate as institutional mediators between the Ciganos and the labour market. However, there are few studies about these public services and this article aims to fill this gap in terms of knowledge on this thematic. This paper is based on the analysis of the results derived from an online survey applied to employment centre directors and officers, aimed at unravelling the motives that justify, in their perspective, the low employability of Ciganos. Despise the results highlighted the greater emphasis on explanations of individual order and lesser reference to factors that are structural or focused on the employers. The contact with Cigano culture appears to be associated with a decrease of the importance of explanations of individual order and a higher weight of the explanations of structural order.info:eu-repo/semantics/publishedVersio

Supersymmetrization of the Radiation Damping

We construct a supersymmetrized version of the model to the radiation damping \cite{03} introduced by the present authors \cite{ACWF}. We dicuss its symmetries and the corresponding conserved Noether charges. It is shown this supersymmetric version provides a supersymmetric generalization of the Galilei algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action can be splited into dynamically independent external and internal sectors.Comment: 9 page