Quantum Chaos and Regularity in Ultracold Fermi Gases

Quantum fluctuation of the energy is studied for an ultracold gas of interacting fermions trapped in a three-dimensional potential. Periodic-orbit theory is explored, and energy fluctuations are studied versus particle number for generic regular and chaotic systems, as well for a system defined by a harmonic confinement potential. Temperature effects on the energy fluctuations are investigated.Comment: 4 pages, 5 figure

Trädgårdsmästarens roll i en rehabiliteringsträdgård

The aim of this essay is to find out how different factors influence the occupational role in a rehabilitation garden. The study is based on two qualitative interviews with and shadowing of the gardeners in the rehabilitation gardens of Alnarp and Gröna Rehab in Gothenburg. The result shows that the main factors that influence the occupational role is the gardener's background, the garden/place, the participants, the team and the possibilities for development. The occupational role appears to consist of several different roles; the team-worker, the activity and project manager, the source of inspiration, the educationalist, the informer, the therapist and the fellow human being. These, combined with the factors that are important for the role, influence each other respectively and to be aware of them is of great importance. Through awareness the gardener can use them in the best possible way. In rehabilitation work with the garden as a tool, it is about developing through the seeking of knowledge by putting together an own unity and science. The goal with the work is the development of the participants. The entire occupational role appears to be very complex. The gardeners' occupational role and the factors that influence him/her can be summarized with the one word: balance.Syftet med uppsatsen är att ta reda på hur olika faktorer påverkar trädgårdsmästarens yrkesroll i en rehabiliteringsträdgård. Studien baseras på två kvalitativa intervjuer med och skuggningar av trädgårdsmästarna i Alnarps rehabiliteringsträdgård samt Gröna Rehab i Göteborg. Resultatet visar att huvudfaktorerna som har betydelse för trädgårdsmästarens yrkesroll är trädgårdsmästarens bakgrund, trädgården/platsen, deltagarna, teamet och utvecklingsmöjligheterna. Yrkesrollen visar sig bestå av flera olika roller; teamarbetaren, aktivitets- projektledaren, inspiratören, pedagogen, informatören, terapeuten och medmänniskan. Dessa, tillsammans med faktorerna som har betydelse för rollen, påverkar varandra sinsemellan och att vara medveten om dem är av stor betydelse. Genom medvetenhet kan trädgårdsmästaren använda sig av dem på bästa sätt. I det rehabiliterande arbetet med trädgården som verktyg handlar det om att utvecklas genom kunskapssökande för att själv sammanställa det till en egen enhet och lära. Målet med arbetet är deltagarnas utveckling. Sammantaget visar sig yrkesrollen vara mycket komplex. Trädgårdsmästarens yrkesroll och de faktorer som påverkar honom/henne kan sammanfattas med ett ord: balans

Can we always get the entanglement entropy from the Kadanoff-Baym equations? The case of the T-matrix approximation

We study the time-dependent transmission of entanglement entropy through an out-of-equilibrium model interacting device in a quantum transport set-up. The dynamics is performed via the Kadanoff-Baym equations within many-body perturbation theory. The double occupancy $< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >$, needed to determine the entanglement entropy, is obtained from the equations of motion of the single-particle Green's function. A remarkable result of our calculations is that $< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >$ can become negative, thus not permitting to evaluate the entanglement entropy. This is a shortcoming of approximate, and yet conserving, many-body self-energies. Among the tested perturbation schemes, the $T$-matrix approximation stands out for two reasons: it compares well to exact results in the low density regime and it always provides a non-negative $< \hat{n}_{R \uparrow} \hat{n}_{R \downarrow} >$. For the second part of this statement, we give an analytical proof. Finally, the transmission of entanglement across the device is diminished by interactions but can be amplified by a current flowing through the system.Comment: 6 pages, 6 figure

Crossover på bokmarknaden

In Sweden and abroad, crossover literature (meaning children's books that are read and appreciated by adults as well) has been one of the more noticeable publishing trends of the new millennium. The aim of this thesis is to examine how Swedish publishing houses are working with crossover fiction, both with the genre as a whole and with individual novels. The method is an analysis of the packaging of a few select crossover books, their publishing houses and interviews with people from the book industry. In order to analyse packaging we have chosen literary theorist Gérard Genette’s ideas about paratext, and Publishing Studies professor Claire Squires use of the concept. Squires examines how marketing, where paratext is a notable part, contributes in defining what genre is in the literary marketplace. The results of our study show that publishers working with crossover literature face many obstacles. Problems include the lack of a generally agreed upon definition of and the unpreparedness of the Swedish book industry when handling books with a dual audience. There is simply no category for works found in between children’s and adult literature, a problem that could be solved by focusing on genre instead of age. Regarding packaging, there is no obvious way to design and market crossover books. But our study shows a frequent emphasis on emotion in copy texts, blurbs, titles and also in the often graphic cover, which seems to be what both teenagers and adults respond to. This also applies to the general view of crossover literature as a genre of feeling as expressed by publishers, readers, critics and authors

Anthropogenic microlitter in wastewater and marine samples from Ny-Ålesund, Barentsburg and Signehamna, Svalbard

Plastic pollution is recognized as a serious threat to the marine environment by the UN, the EU through the Marine Strategy Framework Directive, the Arctic council, the Nordic council, and national governments worldwide. Marine litter may reach the Arctic with ocean currents from global and regional sources, but may also originate from local emissions related to shipping and fishing activities, runoff from land based industries, dumping sites and wastewater outlets. Wastewater outlets are identified as important sources of microplastics to the marine environment in temperate areas but have received less attention in the Arctic. Wastewater treatment is generally lacking in the Arctic, and in smaller settlements, handling of wastewater (including sewage water) and garbage is comparable to conditions observed in developing countries. In Svalbard, wastewater treatment is absent aside from a small treatment plant in Hornsund and the recently installed treatment plant in Ny-Ålesund. The aim of this investigation was to quantify and characterize anthropogenic microparticles (AMPs: particles <5 mm of manmade or modified materials, e.g. plastics, paints, rubber and textile fibers) in wastewater from the recently installed treatment plant in Ny-Ålesund (Kongsfjorden), in the marine environment close to the Russian settlement Barentsburg (Grønnfjorden), and in Signehamna (Krossfjorden) far from permanent land-based human impact. Samples of seawater, marine sediments and beach sediments were collected and analyzed for AMPs using optical and spectroscopic techniques. AMPs were found at all sites and in all matrices investigated in this study. AMPs identified in wastewater and seawater were dominated by fibres (both non-synthetic and synthetic) while AMPs identified in sediment samples were dominated by fragments. Higher concentrations of AMPs and higher polymeric diversity was observed closer to human activities; in sediments close to Ny-Ålesund wastewater outlet and in seawater close to both Barentsburg and Ny-Ålesund, as compared to the remote site at Signehamna. Based on this investigation, as much as 99 % of the incoming AMPs may be retained by the wastewater treatment plant in Ny-Ålesund. It is thus clear that installation of appropriate wastewater treatment systems can substantially reduce the release of anthropogenic microlitter and potential associated contaminants to the marine environment. However, this investigation is based on a limited number of samples and a comprehensive investigation should be conducted to determine the true efficiency of the wastewater treatment plant in Ny-Ålesund, covering both temporal and spatial variation. The present report should be used as a first step towards resolving the issue of lacking wastewater treatment in Svalbard and in the Arctic as a whole

Answering Dreyfus's Challenge: Toward a Theory of Concepts without Intellectualism

John McDowell’s debates about concepts with Robert Brandom and Hubert Dreyfus over the past two decades reveal key commitments each philosopher makes. McDowell is committed to giving concepts a role in our embodied coping, extending rational form to human experience. Brandom is committed to defining concepts in a way that helps make rationality distinct. And Dreyfus is committed to explaining how rational understanding develops out of lesser abilities we share with human infants and other animals (I call this “Dreyfus’s challenge”). These commitments appear irreconcilable. I argue to the contrary that they are, in principle, reconcilable, provided we give up their shared “rationalist” commitment to the idea that the rational use of language is necessary for having concepts. First, I exploit Brandom and McDowell’s debate to motivate abandoning the rationalist commitment. Next, I exploit Dreyfus and McDowell’s debate to establish the need for a broader notion of concepts to answer Dreyfus’s challenge. I turn to Elizabeth Camp’s broader notion of concepts as spontaneously, systematically recombinable representations, and establish that it lacks resources for distinguishing human rationality. To resolve that weakness, I integrate Camp’s notion of concepts with John Haugeland’s theory of objectivity, which does make rationality distinct. Finally, drawing my integration of Camp and Haugeland, I propose a way to answer Dreyfus’s challenge, which I call “relaxed holism.” The core of relaxed holism is a cumulative, developmental sequence of three related cognitive abilities: representation, concepts, and metacognition. I argue that relaxed holism also reconciles both McDowell’s commitment to giving normatively governed concepts a role in embodied coping, and Brandom’s commitment to defining concepts in a way that helps make rationality distinct

Some open questions in TDDFT: Clues from Lattice Models and Kadanoff-Baym Dynamics

Two aspects of TDDFT, the linear response approach and the adiabatic local density approximation, are examined from the perspective of lattice models. To this end, we review the DFT formulations on the lattice and give a concise presentation of the time-dependent Kadanoff-Baym equations, used to asses the limitations of the adiabatic approximation in TDDFT. We present results for the density response function of the 3D homogeneous Hubbard model, and point out a drawback of the linear response scheme based on the linearized Sham-Schl\"uter equation. We then suggest a prescription on how to amend it. Finally, we analyze the time evolution of the density in a small cubic cluster, and compare exact, adiabatic-TDDFT and Kadanoff-Baym-Equations densities. Our results show that non-perturbative (in the interaction) adiabatic potentials can perform quite well for slow perturbations but that, for faster external fields, memory effects, as already present in simple many-body approximations, are clearly required.Comment: 15 pages, submitted to Chemical Physic

Valley splitting in strained silicon quantum wells

A theory based on localized-orbital approaches is developed to describe the valley splitting observed in silicon quantum wells. The theory is appropriate in the limit of low electron density and relevant for proposed quantum computing architectures. The valley splitting is computed for realistic devices using the quantitative nanoelectronic modeling tool NEMO. A simple, analytically solvable tight-binding model is developed, it yields much physical insight, and it reproduces the behavior of the splitting in the NEMO results. The splitting is in general nonzero even in the absence of electric field in contrast to previous works. The splitting in a square well oscillates as a function of S, the number of layers in the quantum well, with a period that is determined by the location of the valley minimum in the Brillouin zone. The envelope of the splitting decays as $S^3$. Finally the feasibility of observing such oscillations experimentally in modern Si/SiGe heterostructures is discussed.Comment: 19 pages, including 4 figure