Fermionic decay of a massive scalar in the early Universe

We derive a curved space generalization of a scalar to fermion decay rate with a Yukawa coupling in expanding Friedmann-Robertson-Walker universes. This is done using the full theory of quantum fields in curved spacetime and the added-up transition probability method. It is found that in an expanding universe the usual Minkowskian decay rates are considerably modified for early times. For conformally coupled scalars the decay rate is modified by a positive additive term proportional to the inverse of mass and related to the expansion rate of the Universe. We compare and contrast our results with previous studies on scalar to scalar decay and find that in general the decay channel into fermions is the dominant channel of decay in the very early Universe.Comment: 9 pages, 2 figures. Corrected some minor misprint

Sanoma- ja aikakauslehtimainonta iPadissa

Opinnäytetyön tavoitteena oli selvittää, minkälaisia mainossisältöjä on Applen iPad-laitteessa ilmestyvissä sanoma- ja aikakauslehdissä sekä muodostaa niiden perusteella kattava tyypittely. Tavoitteena oli myös selvittää, miten iPad-lehtien mainokset eroavat paperilehtien mainoksista ja miten iPadin ominaisuuksia on hyödynnetty mainoksissa. Opinnäytetyö oli osa eReading-hanketta, joka on Tivit Oy:n Next Media –ohjelman suurin yrityshanke. Hankkeessa tutkitaan sähköisiä lukulaitteita ja kehitetään niihin sisältövetoisia liiketoimintamalleja. Opinnäytetyön teoreettinen viitekehys koostuu yleisestä markkinointiviestinnän teoriasta, jossa painopisteenä on mainonta sanoma- ja aikakauslehdissä sekä digitaalisen markkinoinnin teoriasta internet- ja mobiilimarkkinointiin keskittyen. Tutkimus tehtiin kvalitatiivista tutkimusmenetelmää käyttäen ja aineistoa analysoitiin sisällönanalyysin ja tyypittelyn keinoin. Aineisto koostui kahdestatoista suomalaisesta ja ulkomaalaisesta sanoma- ja aikakauslehdestä, jotka olivat Blue Wings, Helsingin Sanomat, Ilta-Sanomat, Suomen Kuvalehti, Tekniikan Maailma, Esquire, Financial Times, Newsweek, Project, Time, Wall Street Journal ja Wired. Project-lehti ilmestyy vain iPad-muodossa ja on suunniteltu nimenomaan iPadin ominaisuuksien ehdoilla. Mainossisältöjen tyypittelyn pohjana käytettiin kahta ulottuvuutta: interaktiivisuutta ja koh-distettavuutta. Teoreettisen viitekehyksen perusteella näillä ulottuvuuksilla tarkasteltuna voidaan nähdä iPad-lehtien tarjoamat keskeiset uudistukset ja parannukset mainonnassa perinteiseen sanoma- ja aikakauslehtimainonnan teoriaan verrattuna. Interaktiivisuudella tarkoitetaan multimedian ja iPadin kosketusnäytön sekä liiketunnistimen käyttöä mainonnassa. Kohdistettavuus on lehden mainosten henkilökohtaisuuden ja maantieteellisen alueellisuuden mittari. IPad on luonteeltaan henkilökohtainen kannettava taulutietokone, jossa on sisäänrakennettuna ominaisuutena paikannusmahdollisuus. Aineiston analyysin kautta iPad-lehtien mainossisällöistä pystyttiin luomaan neljä päätyyppiä. Yksinkertaisin tyyppi on staattiset mainokset, jotka ovat lähes suora kopio paperilehden mai-noksista iPad-muotoon muutettuna. Toinen päätyyppi on yksinkertaiset interaktiiviset mainokset, joissa on käytetty jonkin verran multimediaa, mutta mainokset ovat yksinkertaisia ja niitä on vähän. Tutkimuksessa olleet sanomalehtimainokset sijoittuivat tähän ryhmään. Kolmas perustyyppi on monitasoiset interaktiiviset mainokset, joissa on paljon multimediaa ja sitä on käytetty monipuolisesti, mutta iPadin ominaisuuksia ei ole täysin hyödynnetty mainosten suunnittelussa. Suurin osa tutkituista aikakauslehtimainoksista kuului tähän ryhmään. Interaktiivisin ja kohdistetuin päätyyppi on iPad-mainokset. Ne ovat innovatiivisia mainoksia, joiden suunnittelussa on huomioitu iPadin tarjoamat mahdollisuudet ja niitä on käytetty kekseliäästi.The purpose of this thesis was to discover what sort of advertisements there are in magazines and newspapers that are published on the Apple iPad and to formulate an extensive categorisation of the advertisements. Another objective of the research was to establish how the advertisements on the iPad differ from the advertisements in newspapers and magazines and how the features of iPad have been put to use in advertising. The thesis was a part of an eReading project that is the largest project in the Next Media programme of Tivit Oy. This project examines electronic readers and develops content-based business models for them. The theoretical section of this thesis examines general marketing communications theory with a focus on advertising in newspapers and magazines. It also investigates digital marketing theory, addressing internet and mobile marketing. The research was conducted using a qualitative research method. The data was analysed using content analysis and categorisation methods. The data consisted of twelve Finnish and foreign newspapers and magazines, including Blue Wings, Helsingin Sanomat, Ilta-Sanomat, Suomen Kuvalehti, Tekniikan Maailma, Esquire, Financial Times, Newsweek, Project, Time, Wall Street Journal and Wired. Project is a magazine that is published only on the iPad. There were two dimensions that defined the categorisation of the advertisements: interactivity and personalisation/localisation. The major innovations and improvements in the newspaper and magazine advertisements on the iPad compared to the advertisements of the traditional newspapers and magazines can be examined using these two dimensions in the analysis. Interactivity stands for the use of multimedia, the touch screen and the accelerometer of the iPad in the advertisements. Personalisation/localisation signifies the amount of personalisation and geographical localisation in the advertising. IPad is a portable personal tablet pc that has a built-in GPS device. The analysis revealed four main categories of advertisements. The simplest type is “static advertisements”, which are almost direct copies of the advertisements in printed newspapers and magazines converted into iPad format. The second category is “simple interactive advertisements”. Multimedia is used in the advertisements, but the advertisements are simple and scarce. The third category is ”multilevel interactive advertisements”. These magazine advertisements have a considerable number of multimedia that are used extensively, but the various features of the iPad are not entirely utilised. The most interactive and personalised/localised category is “iPad-advertisements”. The advertisements in this fourth category use the special features of the iPad innovatively

KiVa antibullying program in Spain : how teachers implement KiVa lessons

This study focuses on the implementation of KiVa lessons in Spain. KiVa is a whole-school antibullying program designed for children between 6 and 15 years of age, developed in Finland in 2006. The program’s effectiveness has been shown in several occasions. The program consists of two components, which are the universal and the indicated actions. The universal actions are designated to the whole school and their main part are KiVa lessons, delivered by a class teacher. These aim to increase the students’ socio-emotional skills and to emphasize the importance of the group. The KiVa program focuses mainly on the bystanders, not on the bully or the bullied one. The aim of this study was to find out how Spanish teachers implement KiVa lessons, what are the differences between them, whether they are committed to the program implementation and whether the first-year implementation can be considered successful. A semi-structured thematic interview was conducted for 11 primary school teachers from different regions of Spain. The data was coded, and these codes were gathered below three main themes. The main differences between the teachers were in the number of lessons delivered, which varied from 3 to 10 lessons. Some differences were also found in the ways of lesson planning. The teachers’ commitment to the program implementation was quite high, as their attitudes towards the program were positive, as well as their beliefs in their personal and their students’ capabilities, and on the time management. The first-year implementation can be considered mainly successful, as the schools’ directions’ support was evident. However, the number of lessons delivered varied so much, that some guiding on the lesson planning, on the purpose of the lessons and on the selection of the activities could be appropriated

Ising Model on a random network with annealed or quenched disorder

We study the equilibrium properties of an Ising model on a disordered random network where the disorder can be quenched or annealed. The network consists of four-fold coordinated sites connected via variable length one-dimensional chains. Our emphasis is on nonuniversal properties and we consider the transition temperature and other equilibrium thermodynamic properties, including those associated with one dimensional fluctuations arising from the chains. We use analytic methods in the annealed case, and a Monte Carlo simulation for the quenched disorder. Our objective is to study the difference between quenched and annealed results with a broad random distribution of interaction parameters. The former represents a situation where the time scale associated with the randomness is very long and the corresponding degrees of freedom can be viewed as frozen, while the annealed case models the situation where this is not so. We find that the transition temperature and the entropy associated with one dimensional fluctuations are always higher for quenched disorder than in the annealed case. These differences increase with the strength of the disorder up to a saturating value. We discuss our results in connection to physical systems where a broad distribution of interaction strengths is present.Comment: 11 pages including 9 figures. To appear in Phys. Rev.

Hydrodynamics of compressible superfluids in confined geometries

We present a study of the hydrodynamics of compressible superfluids in confined geometries. We use a perturbative procedure in terms of the dimensionless expansion parameter $(v/v_s)^2$ where $v$ is the typical speed of the flow and $v_s$ the speed of sound. A zero value of this parameter corresponds to the incompressible limit. We apply the procedure to two specific problems: the case of a trapped superfluid with a gaussian profile of the local density, and that of a superfluid confined in a rotating obstructed cylinder. We find that the corrections due to finite compressibility which are, as expected, negligible for liquid He, are important but amenable to the perturbative treatment for typical ultracold atomic systems.Comment: 17 pages, including 7 figures. To appear in Journ. Phys.

Superfluid Field response to Edge dislocation motion

We study the dynamic response of a superfluid field to a moving edge dislocation line to which the field is minimally coupled. We use a dissipative Gross-Pitaevskii equation, and determine the initial conditions by solving the equilibrium version of the model. We consider the subsequent time evolution of the field for both glide and climb dislocation motion and analyze the results for a range of values of the constant speed $V_D$ of the moving dislocation. We find that the type of motion of the dislocation line is very important in determining the time evolution of the superfluid field distribution associated with it. Climb motion of the dislocation line induces increasing asymmetry, as function of time, in the field profile, with part of the probability being, as it were, left behind. On the other hand, glide motion has no effect on the symmetry properties of the superfluid field distribution. Damping of the superfluid field due to excitations associated with the moving dislocation line occurs in both cases.Comment: 10 pages 7 figures. To appear in Phys. Rev

Dislocation Mobility and Anomalous Shear Modulus Effect in 4^4He Crystals

We calculate the dislocation glide mobility in solid $^4$He within a model that assumes the existence of a superfluid field associated with dislocation lines. Prompted by the results of this mobility calculation, we study within this model the role that such a superfluid field may play in the motion of the dislocation line when a stress is applied to the crystal. To do this, we relate the damping of dislocation motion, calculated in the presence of the assumed superfluid field, to the shear modulus of the crystal. As the temperature increases, we find that a sharp drop in the shear modulus will occur at the temperature where the superfluid field disappears. We compare the drop in shear modulus of the crystal arising from the temperature dependence of the damping contribution due to the superfluid field, to the experimental observation of the same phenomena in solid $^4$He and find quantitative agreement. Our results indicate that such a superfluid field plays an important role in dislocation pinning in a clean solid $^4$He at low temperatures and in this regime may provide an alternative source for the unusual elastic phenomena observed in solid $^4$He.Comment: 17 pages, 2 figures. To appear in JLT