3,063 research outputs found
Light-matter interaction in photonic metasurfaces
No full textIn the present work, we discuss the properties of the complex (i.e., including real and
imaginary part of the eigenvalues) eigenmodes in dielectric photonic metasurfaces. These
structures are usually composed of a multi-layered waveguide core with a generic in-
plane periodic patterning. The presence of active materials, i.e. materials sustaining
excitonic resonances, can result in the so-called radiation-matter strong-coupling regime.
This phenomenon manifests itself with the formation of the elementary excitations called
exciton-polaritons, for brevity only polaritons. The study of these elementary excitations is
motivated from either an application point of view, or a fundamental interest. Indeed, these
elementary excitations in solids can serve as a platform for the study of various exotic
states of matter. For example, polaritons can display superfluid behaviour and undergo
Bose-Einstein condensation at relatively high temperature. On the other hand, one of the
final goals of this research field is to replace electrons with photons and polaritons as
information carriers in circuits. In this thesis, we ultimately studied the dispersions, losses,
symmetry and topological properties of either photons or polaritons in the aforementioned
metamaterials. The control over these quantities are essentials for any targeted application.
Throughout the thesis, several algorithms have been used to investigate the physics
of the elementary excitations in metasurfaces, such as the guided mode expansion, the
scattering matrix (or rigorous coupled wave analysis) and the finite-difference time-domain
methods. Most of the theoretical predictions presented in this thesis are validated by
experimental measurements. As the main original contribution, we extended the quantum
theory of light-matter coupling to metasurfaces coupled with an arbitrary number of active
layers. Thanks to the newly introduced theory, it is possible to take into account either
classical active multi quantum well systems, or two dimensional semiconductor materials
and perovskite layers coupled with the photonic modes. We compared the results of the
generalised theory with semi classical results, and experiments. In each case, we obtained
a good agreement for both the real dispersions of the polaritonic modes and the losses.
In addition, we studied the symmetry and topological properties of bound states in the
continuum (BICs). The BIC is a peculiar type of solution of the wave equation, in this
case Maxwell equations, that is perfectly confined despite the fact it lives in a continuum
of radiative solutions. Among its exotic properties, we can identify its singularity in
the far-field emission pattern, resulting in a polarisation of electromagnetic radiation.
We demonstrated that this topological singularity can be transferred to BIC coupled to
excitons, namely polaritonic-BIC (pol-BIC). Finally, we studied a platform where the
non-linear polariton-polariton scattering processes create a trap for the pol-BIC leading to
Bose-Einstein phase transition with extremely low condensation threshold.In the present work, we discuss the properties of the complex (i.e., including real and
imaginary part of the eigenvalues) eigenmodes in dielectric photonic metasurfaces. These
structures are usually composed of a multi-layered waveguide core with a generic in-
plane periodic patterning. The presence of active materials, i.e. materials sustaining
excitonic resonances, can result in the so-called radiation-matter strong-coupling regime.
This phenomenon manifests itself with the formation of the elementary excitations called
exciton-polaritons, for brevity only polaritons. The study of these elementary excitations is
motivated from either an application point of view, or a fundamental interest. Indeed, these
elementary excitations in solids can serve as a platform for the study of various exotic
states of matter. For example, polaritons can display superfluid behaviour and undergo
Bose-Einstein condensation at relatively high temperature. On the other hand, one of the
final goals of this research field is to replace electrons with photons and polaritons as
information carriers in circuits. In this thesis, we ultimately studied the dispersions, losses,
symmetry and topological properties of either photons or polaritons in the aforementioned
metamaterials. The control over these quantities are essentials for any targeted application.
Throughout the thesis, several algorithms have been used to investigate the physics
of the elementary excitations in metasurfaces, such as the guided mode expansion, the
scattering matrix (or rigorous coupled wave analysis) and the finite-difference time-domain
methods. Most of the theoretical predictions presented in this thesis are validated by
experimental measurements. As the main original contribution, we extended the quantum
theory of light-matter coupling to metasurfaces coupled with an arbitrary number of active
layers. Thanks to the newly introduced theory, it is possible to take into account either
classical active multi quantum well systems, or two dimensional semiconductor materials
and perovskite layers coupled with the photonic modes. We compared the results of the
generalised theory with semi classical results, and experiments. In each case, we obtained
a good agreement for both the real dispersions of the polaritonic modes and the losses.
In addition, we studied the symmetry and topological properties of bound states in the
continuum (BICs). The BIC is a peculiar type of solution of the wave equation, in this
case Maxwell equations, that is perfectly confined despite the fact it lives in a continuum
of radiative solutions. Among its exotic properties, we can identify its singularity in
the far-field emission pattern, resulting in a polarisation of electromagnetic radiation.
We demonstrated that this topological singularity can be transferred to BIC coupled to
excitons, namely polaritonic-BIC (pol-BIC). Finally, we studied a platform where the
non-linear polariton-polariton scattering processes create a trap for the pol-BIC leading to
Bose-Einstein phase transition with extremely low condensation threshold
Rozpor ako východisko, láska ako smer u Simone Weilovej (Contradiction as base, Love as direction in writings of Simone Weil)
No full textArticle is explaining contradiction and love, Simone Weil‘s essential terms of hermeneutics of human Being. It introduces close relation of these terms with her understanding of God as well as with her overall concept of religion. Author also mentions Simone Weil‘s inspirations with philosophical and spiritual concepts of the East
“I beg you to tell me what has become of Djamila”: The Political Mobilization of Simone de Beauvoir’s Readers During the Boupacha Affair
No full textBy Sophia Millman This is a condensed version of a Masters thesis dedicated to the political mobilization of Simone de Beauvoir’s readers. The citations from the letters were translated from French by the author. *** On June 2, 1960, the French government ordered all copies of the daily Algiers edition of Le Monde seized and destroyed to suppress the publication of Simone de Beauvoir’s article “Pour Djamila Boupacha.” Beauvoir, a self-professed “woman of letters”, not “of action[1]”, and one ..
A comparative study of form and theology in the works of Flannery O'Connor and Simone Weil
No full textIn this comparative study of the form and theology of Flannery O'Connor and Simone Weil I interrogate how Weil's philosophical writings and her theology illuminate O'Connor's use of both narrative and non-fictional forms, and her Catholicism. The Introduction analyses how Weil's concept of superposed reading provides a new method of approaching both O'Connor, her writings, and O'Connor
studies, and focuses on how such apparently different women interconnect. Chapter One explores how both Weil and O'Connor attempt to write their theologies on the
souls of their readers yet are each subject to constraints imposed by form. Weil's concept of locating equilibrium between incommensurates is discussed, and her
distinctively philosophical approach to fictions and fictionality is used to investigate O'Connor's notion of prophetic fictions and the writer's role. Chapter Two assesses how both writers revivify Christian paradoxes. Weil's monstrous concept of affiiction, and O'Connor's use of the grotesque genre to jolt secular man into an
awareness of the sacred are scrutinised. Chapter Three studies how both writers consider an encounter between God and man is possible through the action of grace. My Conclusion interrogates how Weil's work can deepen our understanding of O'Connor's writings, and examines how successful O'Connor is at realising a truly
Christian literature. I conclude that despite being a writer of powerful fictions, O'Connor can not be totally successful in her mission as writer-prophet because
ultimately fiction escapes orthodoxy
Microlinices benthovus Simone 2014
No full textbenthovus, Microlinices Simone, 2014 Microlinices benthovus Simone, 2014: 575–578 (figs 6A–J, 7A–H, 11A–C). Gastropoda, Naticidae Paratypes (22 spc): MZSP 105269. Paratypes 1 (15 spc): MZSP 105270. Paratypes 2 (16 spc): MZSP 105271. Paratypes 3 (7 spc): MZSP 105272. Localities: Brazil, Espírito Santo, off Itaúnas, Abrolhos Slope, 18°59' S, 37°50' W, MD55 sta. DC 73, 637 m depth, 27 May 1987; 1) 19°00' S, 37°48' W, MD55 sta. DC72, 950– 1050 m, 27 May 1987; 2) off Regência, 19°40' S, 37°48' W, MD55 sta. CB77, 790– 940 m depth, 27 May 1987; 3) off Itaúnas, Abrolhos Slope, 19°01' S, 37°47' W, MD55 sta. CB79, 1500–1575 m depth, 28 May 1987. Collectors: P. Bouchet, J.H. Leal and B. Métivier. Preservation: Dry. Remarks: Former MNHN, Paris. The catalogue number MZSP 105250 is mentioned twice in Simone’s (2014) paper, among the paratypes of M. ibitingus Simone, 2014 and M. benthovus. This duplicity was a mistake by the author: the latter is an erroneous designation and should be disregarded. The only valid paratype lots for M. benthovus are the ones shown above.Published as part of Cavallari, Daniel C., Dornellas, Ana Paula S. & Simone, Luiz Ricardo L., 2016, Second annotated list of type specimens of molluscs deposited in the Museu de Zoologia da Universidade de São Paulo, Brazil, pp. 1-59 in European Journal of Taxonomy 213 on page 10, DOI: 10.5852/ejt.2016.213, http://zenodo.org/record/384012
Was bringt die Föderalismusreform? Wahrscheinliche Effekte der geänderten Zustimmungspflicht
No full textThe recently enacted reform of German federalism is supposed to make legislation faster, more efficient and better. To what extent are these expectations justified? In order to assess the likely effects of the reform, this study uses a research design that was recently applied by the Research and Reference Services of the German Bundestag (parliament): we estimate the future effects of the reform by analyzing the impact it would have had on the legislation in the 14th and 15th term of the Bundestag if it had already been been in force at that time. In particular we ask: To what extent would the number of laws requiring the consent of the states' chamber, the Bundesrat, have been reduced? Which type of laws would have been affected by this reduction - the more controversial ones, or the less controversial ones? Which policy sectors would have seen the greatest reduction? How much would the reduction have increased the government's capacity to act effectively? Would the legislative process have been accelerated? -- Die verabschiedete Föderalismusreform soll die Gesetzgebung in Deutschland schneller, effizienter und besser machen. Inwiefern sind diese Erwartungen berechtigt? Zur Abschätzung der Reformfolgen auf die Bundesgesetzgebung folgen wir in dem vorliegenden Working Paper einer Vorgehensweise, die der Wissenschaftliche Dienst des Bundestages kürzlich in einer Studie angewandt hat: Die Auswirkungen der Föderalismusreform insbesondere auf die Zustimmungspflicht werden anhand der Gesetzgebung der 14. und 15. Legislaturperiode untersucht. Wir fragen insbesondere: Wie stark hätte sich der Anteil der Zustimmungsgesetze verringert, wenn die neuen Zustimmungsregeln schon in diesen beiden Legislaturperioden gegolten hätten? Wären eher zwischen Regierung strittige oder unstrittige Gesetze von der Zustimmungspflicht befreit worden? Welche Politikbereiche wären betroffen? Wie sehr hätte sich die politische Handlungsfreiheit der Bundesregierung erhöht? Wäre die Gesetzgebung durch die veränderten Zustimmungsregeln beschleunigt worden?
Crystal Structure of the Trigonal Form of Human Plasma Retinol-Binding Protein at 2.5 Å Resolution.
No full textSmallsat mission to Didymos: enhanced GNC design for the LICIA science return maximisation
No full textThe interest in near earth objects (NEOs) has widely spread among space agencies during the past decades, not only due to the valuable scientific data these objects can provide, but also for the potential hazard they represent for our planet. In particular, to date there still isn't a validated technique to deflect NEOs on a collision course with Earth. The DART mission, developed by NASA, aims at filling this gap, by testing the effectiveness of a kinetic impactor on the binary asteroid system”Didymos”. In 2022 the spacecraft will hit the smaller asteroid of the binary system, slowing down the moonlet speed with respect to the larger body, permitting the assessment of the impact effectiveness by ground observation measurements. The impact will also generate a cone of ejected particles, of great interest for current numerical impact models validation, which however will be hardly visible from ground. In this context, a bilateral agreement between NASA and Italian Space Agency (ASI) allowed to embark a 6-units CubeSat on DART, called Light Italian Cubesat for Imaging of Asteroids (LICIA). Deployed before the impact, it will fly by the asteroid at the right distance to observe the ejecta evolution and will also be exploited for observation of the asteroid's side not visible from DART, to help estimating the overall volume. The LICIA spacecraft and mission are being developed by ASI through an italian consortium composed by Istituto Nazionale di Astrofisica (INAF), Università di Bologna (UniBo), Argotec, and Politecnico di Milano (PoliMi), respectively covering the fields of mission science and payload, orbit determination, platform development, and mission analysis. The present paper covers the topic of attitude guidance and control design, to ensure the best performance for target pointing during the flyby. The most up-to-date trajectory is taken as baseline scenario to explore various strategies in terms of slew maneuvers to be performed, and optimization for the parameters of the controller. Uncertainties, for the platform and the environment, are introduced to evaluate such strategies in non-nominal, realistic scenarios, with deviations of the trajectory and changes in the flyby distance from the target. Results are compared and the best guidance and control strategy is selected as preliminary baseline. Next steps in the closed-loop architecture development, and related expected issues to be solved, are discussed
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