Magnetic nanocomposites at microwave frequencies

Most conventional magnetic materials used in the electronic devices are ferrites, which are composed of micrometer-size grains. But ferrites have small saturation magnetization, therefore the performance at GHz frequencies is rather poor. That is why functionalized nanocomposites comprising magnetic nanoparticles (e.g. Fe, Co) with dimensions ranging from a few nm to 100 nm, and embedded in dielectric matrices (e.g. silicon oxide, aluminium oxide) have a significant potential for the electronics industry. When the size of the nanoparticles is smaller than the critical size for multidomain formation, these nanocomposites can be regarded as an ensemble of particles in single-domain states and the losses (due for example to eddy currents) are expected to be relatively small. Here we review the theory of magnetism in such materials, and we present a novel measurement method used for the characterization of the electromagnetic properties of composites with nanomagnetic insertions. We also present a few experimental results obtained on composites consisting of iron nanoparticles in a dielectric matrix.Comment: 20 pages, 10 figures, 5 table

Developing LCA-based benchmarks for sustainable consumption - for and with users

This article presents the development process of a consumer-oriented, illustrative benchmarking tool enabling consumers to use the results of environmental life cycle assessment (LCA) to make informed decisions. Active and environmentally conscious consumers and environmental communicators were identified as key target groups for this type of information. A brochure presenting the benchmarking tool was developed as an participatory, iterative process involving consumer focus groups, stakeholder workshops and questionnaire-based feedback. In addition to learning what works and what does not, detailed suggestions on improved wording and figures were obtained, as well as a wealth of ideas for future applications

Scaling Exponents in the Incommensurate Phase of the Sine-Gordon and U(1) Thirring Models

In this paper we study the critical exponents of the quantum sine-Gordon and U(1) Thirring models in the incommensurate phase. This phase appears when the chemical potential $h$ exceeds a critical value and is characterized by a finite density of solitons. The low-energy sector of this phase is critical and is described by the Gaussian model (Tomonaga-Luttinger liquid) with the compactification radius dependent on the soliton density and the sine-Gordon model coupling constant $\beta$. For a fixed value of $\beta$, we find that the Luttinger parameter $K$ is equal to 1/2 at the commensurate-incommensurate transition point and approaches the asymptotic value $\beta^2/8\pi$ away from it. We describe a possible phase diagram of the model consisting of an array of weakly coupled chains. The possible phases are Fermi liquid, Spin Density Wave, Spin-Peierls and Wigner crystal.Comment: 10pages; Improved version; Submitted to Physical Review

Interaction Properties of the Periodic and Step-like Solutions of the Double-Sine-Gordon Equation

The periodic and step-like solutions of the double-Sine-Gordon equation are investigated, with different initial conditions and for various values of the potential parameter $\epsilon$. We plot energy and force diagrams, as functions of the inter-soliton distance for such solutions. This allows us to consider our system as an interacting many-body system in 1+1 dimension. We therefore plot state diagrams (pressure vs. average density) for step-like as well as periodic solutions. Step-like solutions are shown to behave similarly to their counterparts in the Sine-Gordon system. However, periodic solutions show a fundamentally different behavior as the parameter $\epsilon$ is increased. We show that two distinct phases of periodic solutions exist which exhibit manifestly different behavior. Response functions for these phases are shown to behave differently, joining at an apparent phase transition point.Comment: 17pages, 15 figure

The Brothers and Sisters of the Ozu Family: Constructing Family Roles and Social Dynamics in the Post-War Films of Ozu Yasujirô 1947-1962

This dissertation deals with the post-war films of Japanese filmmaker Ozu Yasujirô. It focuses on the production and construction of family and gender roles in the fifteen films that Ozu directed between 1947 and 1962. These films serve as the primary source material. The study combines film history and cultural history and adds elements from sociology, gender studies and East-Asian studies. It looks at the post-war period in Japanese history as a time, when the nation undertook a large-scale renegotiation of social roles pertaining to categories such as age, gender, and social status, and highlights the role of cinema during this time of turmoil. It studies, first, the ways in which Ozu constructs the families who serve as the lead characters of his films and second, what kind of values, attitudes and notions are communicated through this depiction. The dissertation consists of nine chapters. The first two analyse Ozu’s career and the cultural framework in which he operated. They look at the director’s development as an artist and track down the elements of his film-making that characterise his personal angle to film narratives and creation of characters. An optimal viewing strategy for Ozu’s work, called ‘comparative individualism’, is also introduced. Furthermore, the chapters consider the effect of outside forces, such as the Japanese studio system and the film censorship of the occupation period. Chapters 3 to 7 cover the various roles and repeated character types of Ozu’s output, as well as the cultural social expectations that are attached to these categories and points in human life. The dissertation discusses the juxtaposition between the custom of arranged marriages, and the alternative that challenges it, unions based on romantic attraction. The study also offers individual chapters to the expected life path for both men and women and what kind of arguments the films contain in the display of this everyday reality. Chapter 6 covers how Ozu depicts childhood in both the immediate post-war, and later in the more comfortable period of economic growth in the 1950s. It is then followed by an assessment of the material aspects and physical reality of domestic life present in these films in chapter 7. The final two chapters steer towards the more abstract subject matters of distance (chapter 8) and change (chapter 9), in order to gain the best possible understanding about the emotional texture woven into Ozu’s character networks. This dissertation argues that cinema has unique abilities to affect the way social roles are viewed in society. It makes the case that Ozu’s films are more argumentative and political than has been previously established. The study looks at gender and family roles as social constructions that can be maintained, questioned, or challenged through film narratives. It argues that Ozu can even take part in these activities simultaneously in his attempt to capture his society and the direction in which it is moving. By focusing on the way the networks of social roles are assembled and how characters are depicted, the dissertation shows both the significance of the post-war era in the societal transformation of Japan, as well as the important role played by cultural products in this process.---- Tämä väitöskirja käsittelee japanilaisen elokuvantekijän Ozu Yasujirôn sodanjälkeisiä elokuvia. Se keskittyy perhe- ja sukupuoliroolien tuottamiseen ja esitystapaan niissä viidessätoista filmissä, jotka Ozu ohjasi vuosien 1947 ja 1962 välillä. Nämä elokuvat toimivat väitöskirjan pääasiallisena lähdemateriaalina. Tämä tutkimus on osa elokuva- ja kulttuurihistoriaa ja sisältää elementtejä sosiologiasta, sukupuolentutkimuksesta ja Itä-Aasian tutkimuksesta. Se tarkastelee sodanjälkeisiä vuosikymmeniä aikana, jolloin japanilainen yhteiskunta todisti laajamittaisen sosiaalisten roolien uudelleenneuvottelun iän, sukupuolen ja sosiaalisen statuksen kaltaisissa kategorioissa. Tutkimus korostaa elokuvan roolia tässä yhteiskunnallisessa myllerryksessä. Väitöskirja tutkailee ensinnäkin tapoja, joilla Ozun elokuvien perheet rakentuvat, ja toiseksi sitä, millaisia arvoja, asenteita ja ajatuksia kuvauksen kautta välitetään. Väitöskirja koostuu yhdeksästä luvusta. Kaksi ensimmäistä analysoivat Ozun uraa ja sitä kulttuurillista viitekehystä, jossa hän työskenteli. Ne pohtivat hänen kehitystään taiteilijana ja tuovat esiin ne elokuvanteon elementit, joissa korostuu hänen persoonallinen tapansa rakentaa elokuvanarratiiveja ja hahmoja. Tutkimus esittelee myös optimaalisen katselustrategian, jonka kautta syventyä tähän tuotantoon, nimeltä ”vertaileva individualismi” (engl. comparative individualism). Lisäksi luvut pohtivat elokuvien ulkopuolisten voimien vaikutusta, kuten japanilaista studiojärjestelmää ja miehitysvuosina voimassa ollutta filmisensuuria. Luvut 3–7 kattavat erilaisten roolien ja elämänvaiheiden kirjon Ozun elokuvissa, sekä ne sosiaaliset odotukset, joita näihin kategorioihin assosioidaan. Väitöskirja pureutuu vastakkainasetteluun järjestettyjen avioliittojen ja romanttisen rakkauden pohjalta solmittujen liittojen välillä. Se myös sisältää omat lukunsa miesten ja naisten oletetuille elämänpoluille ja sille, millaisia argumentteja filmit sisältävät tämän arkitodellisuuden kuvauksessa. Kuudes luku käsittelee tapoja, joilla Ozu kuvaa lapsuutta sekä sodan päättymistä seuranneina vaikeina aikoina että 1950-luvun taloudellisessa nousukaudessa. Seitsemäs luku analysoi materiaalista todellisuutta ja fyysistä toimintaa Ozun kuvaamassa perhearjessa. Viimeiset kaksi lukua syventyvät abstraktimpiin aiheisiin, etäisyyteen (luku 8) ja muutokseen (luku 9) saadakseen täyden ymmärryksen Ozun perheverkostojen emotionaalisesta tekstuurista. Väitöskirja argumentoi, että elokuvalla on ainutlaatuisia kykyjä vaikuttaa tapaan, jolla sosiaaliset roolit koetaan yhteiskunnassa. Se väittää, että Ozun elokuvat ovat argumentoivampia ja poliittisempia kuin mitä on aiemmin esitetty. Teos tutkii perhe- ja sukupuolirooleja sosiaalisina konstruktioina, jota elokuvat voivat kuvastollaan ylläpitää, haastaa tai joille ne voivat esittää vaihtoehtoja. Väitöskirja esittää Ozun kykenevän näihin akteihin jopa samanaikaisesti yrityksessään vangita aikalaisyhteiskunta ja sen suunta. Keskittymällä tapoihin, joilla sosiaalisten roolien verkot luodaan ja kuinka hahmot kuvataan, väitöskirja näyttää sodanjälkeisen aikakauden merkittävyyden Japanin yhteiskunnallisessa murroksessa ja sen tärkeän roolin, jonka kulttuurituotteet näyttelivät tässä prosessissa

Permeability of Three-Dimensional Random Fiber Webs

We report the results of essentially ab initio simulations of creeping flow through large three-dimensional random fiber webs that closely resemble fibrous sheets such as paper and nonwoven fabrics. The computational scheme used in this Letter is that of the lattice-Boltzmann method and contains no free parameters concerning the properties of the porous medium or the dynamics of the flow. The computed permeability of the web is found to be in good agreement with experimental data, and confirms that permeability depends exponentially on porosity over a large range of porosity.Peer reviewe

Thinking about Later Life: Insights from the Capability Approach

A major criticism of mainstream gerontological frameworks is the inability of such frameworks to appreciate and incorporate issues of diversity and difference in engaging with experiences of aging. Given the prevailing socially structured nature of inequalities, such differences matter greatly in shaping experiences, as well as social constructions, of aging. I argue that Amartya Sen’s capability approach (2009) potentially offers gerontological scholars a broad conceptual framework that places at its core consideration of human beings (their values) and centrality of human diversity. As well as identifying these key features of the capability approach, I discuss and demonstrate their relevance to thinking about old age and aging. I maintain that in the context of complex and emerging identities in later life that shape and are shaped by shifting people-place and people-people relationships, Sen’s capability approach offers significant possibilities for gerontological research

An algebraic approach to the Tavis-Cummings problem

An algebraic method is introduced for an analytical solution of the eigenvalue problem of the Tavis-Cummings (TC) Hamiltonian, based on polynomially deformed su(2), i.e. su_n(2), algebras. In this method the eigenvalue problem is solved in terms of a specific perturbation theory, developed here up to third order. Generalization to the N-atom case of the Rabi frequency and dressed states is also provided. A remarkable enhancement of spontaneous emission of N atoms in a resonator is found to result from collective effects.Comment: 13 pages, 7 figure

Tree height strongly affects estimates of water-use efficiency responses to climate and CO2 using isotopes

Various studies report substantial increases in intrinsic water-use efficiency (Wi), estimated using carbon isotopes in tree rings, suggesting trees are gaining increasingly more carbon per unit water lost due to increases in atmospheric CO2. Usually, reconstructions do not, however, correct for the effect of intrinsic developmental changes in Wi as trees grow larger. Here we show, by comparingWi across varying tree sizes at one CO2 level, that ignoring such developmental effects can severely affect inferences of trees' Wi. Wi doubled or even tripled over a trees' lifespan in three broadleaf species due to changes in tree height and light availability alone, and there are also weak trends for Pine trees. Developmental trends in broadleaf species are as large as the trends previously assigned to CO2 and climate. Credible future tree ring isotope studies require explicit accounting for species-specific developmental effects before CO2 and climate effects are inferred.Peer reviewe