Theory of interfacial charge-transfer complex photophysics in π\pi-conjugated polymer-fullerene blends

We present a theory of the electronic structure and photophysics of 1:1 blends of derivatives of polyparaphenylenevinylene and fullerenes. Within the same Coulomb-correlated Hamiltonian applied previously to interacting chains of single-component $\pi$-conjugated polymers, we find an exciplex state that occurs below the polymer's optical exciton. Weak absorption from the ground state occurs to the exciplex. We explain transient photoinduced absorptions in the blend, observed for both above-gap and below-gap photoexcitations, within our theory. Photoinduced absorptions for above-gap photoexcitation are from the optical exciton as well as the exciplex, while for below-gap photoexcitation induced absorptions are from the exciplex alone. In neither case are free polarons generated in the time scale of the experiment. Importantly, the photophysics of films of single-component $\pi$-conjugated polymers and blends can both be understood by extending Mulliken's theory of ground-state charge transfer to the case of excited-state charge transfer.Comment: 9 pages, 8 figure

Correlated-electron description of the photophysics of thin films of π\pi-conjugated polymers

We extend Mulliken's theory of ground state charge transfer in a donor-acceptor complex to excited state charge transfer between pairs of identical $\pi$-conjugated oligomers, one of which is in the optically excited state and the other in the ground state, leading to the formation of a charge-transfer exciton. Within our theory, optical absorptions from the charge-transfer exciton should include a low energy intermolecular charge-transfer excitation, as well as distinct intramolecular excitations from both the neutral delocalized exciton component and the Coulombically bound polaron-pair component of the charge-transfer exciton. We report high order configuration-interaction calculations for pairs of oligomers of poly-paraphenylenevinylene (PPV) that go beyond our previous single configuration-interaction calculation and find all five excited state absorptions predicted using heuristic arguments based on the Mulliken concept. Our calculated excited state absorption spectrum exhibits strong qualitative agreement with the complete wavelength-dependent ultrafast photoinduced absorption in films of PPV derivatives, suggesting that a significant fraction of the photoinduced absorption here is from the charge-transfer exciton. We make detailed comparisons to experiments, and a testable experimental prediction

Entre l’extrême et l’ordinaire : le réalisme traumatique chez Ruth Klüger et Charlotte Delbo

Cet article entend montrer comment s’exprime, dans l’écriture du témoignage, une forme de « réalisme traumatique ». À la lumière d’une étude précise de certains passages des Mémoires de Ruth Klüger, Weiter leben [Refus de témoigner] et de la trilogie de Charlotte Delbo, Auschwitz et après, nous verrons comment chaque auteur tisse des liens entre l’extrême et l’ordinaire afin de représenter l’« univers concentrationnaire » nazi. Au surplus, les textes de Klüger et de Delbo offrent des matériaux à une entreprise critique s’inscrivant dans la mouvance des théories récentes du trauma, dont l’influence est considérable dans le champ des études culturelles ou littéraires. Alors que certains théoriciens envisagent la catégorie du trauma d’un point de vue totalisant et homogénéisant, les textes examinés ici nous invitent à penser la violence traumatique sous un angle différent. Ils permettent également de saisir la portée politique du témoignage et d’approfondir notre connaissance de la violence extrême tout en favorisant une meilleure reconnaissance sociale du contexte social post-traumatique.This essay develops an account of testimony as a form of “traumatic realism.” Based on close analysis of passages in Ruth Klüger’s memoir Weiter leben [Landscapes of memory] and Charlotte Delbo’s trilogy Auschwitz et après [Auschwitz and after] the essay reveals how each author interweaves the extreme and the everyday in order to portray the “concentrationary universe” of the Nazi camps. In addition, the texts of Klüger and Delbo provide resources for a critical engagement with influential recent theories of trauma in literary and cultural studies. While some theorists risk absolutizing and homogenizing the category of trauma, the texts discussed here help us to develop a differentiated account of traumatic violence. They also help us to reflect on the political impact of testimony. Traumatic realist texts, such as those by Klüger and Delbo, simultaneously produce knowledge of extreme violence and prompt public recognition of a post-traumatic social context

MOND rotation curves for spiral galaxies with Cepheid-based distances

Rotation curves for four spiral galaxies with recently determined Cepheid-based distances are reconsidered in terms of modified Newtonian dynamics (MOND). For two of the objects, NGC 2403 and NGC 7331, the rotation curves predicted by MOND are compatible with the observed curves when these galaxies are taken to be at the Cepheid distance. For NGC 3198, the largest distance for which reasonable agreement is obtained is 10% smaller than the Cepheid-based distance; i.e., MOND clearly prefers a smaller distance. This conclusion is unaltered when new near-infrared photometry of NGC 3198 is taken as the tracer of the stellar mass distribution. For the large Sc spiral, NGC 2841, MOND requires a distance which is at least 20% larger than the Cepheid-based distance. However, the discrepancy of the Tully-Fisher and SNIa distances with the Cepheid determination casts some doubt upon the Cepheid method in this case.Comment: Accepted for publication in astronomy and astrophysics 9 pages, 9 figure

Nyhetast på Åland : en studie i lokal mediekonkurrens och lokal nyhetsrapportering

Only abstract. Paper copies of master’s theses are listed in the Helka database (http://www.helsinki.fi/helka). Electronic copies of master’s theses are either available as open access or only on thesis terminals in the Helsinki University Library.Vain tiivistelmä. Sidottujen gradujen saatavuuden voit tarkistaa Helka-tietokannasta (http://www.helsinki.fi/helka). Digitaaliset gradut voivat olla luettavissa avoimesti verkossa tai rajoitetusti kirjaston opinnäytekioskeilla.Endast sammandrag. Inbundna avhandlingar kan sökas i Helka-databasen (http://www.helsinki.fi/helka). Elektroniska kopior av avhandlingar finns antingen öppet på nätet eller endast tillgängliga i bibliotekets avhandlingsterminaler.Åland är ett medietätt område med två dagstidningar, Nya Åland och tidningen Åland, och en public service-radiokanal, Ålands Radio, och en befolkning på 27 734 invånare. Det lokala medieutbudet är stort, bevakningen är intensiv och medierna har ett starkt fäste i ålänningarnas vardag. I min avhandling pro gradu undersöker jag om den lokala mediekonkurrensen leder till fler olika nyheter eller till en likriktad nyhetsrapportering, där alla medier tar upp samma händelser. År 2007 genomgick Nya Åland och tidningen Åland reformer, båda övergick från fem- till sexdagarsutgivning och samtidigt blev tidningen Åland likt konkurrenten en morgontidning. Jag har undersökt ifall de här reformerna ledde till en mer likriktad nyhetsrapportering. Oumbärliga verk för min avhandling var Gunnar Nygrens Skilda medievärldar, Larsåke Larssons Nyheter i samspel samt Robert G. Picards forskning om mediekonkurrens. Min metod är den kvantitativa innehållsanalysen, genom vilken jag har jämfört innehållet i tidningen Åland, Nya Åland och Ålands Radios Ålandsnytt-sändningar sinsemellan, under en period på totalt fyra veckor, år 2007 och 2008. Enligt min studie tycks det stora medieutbudet och konkurrensen gynna mångfald. Omkring hälften av nyheterna i Nya Åland, tidningen Åland och Ålands Radio var unika år 2008. Endast 45 stycken nyheter var gemensamma för alla tre medier. I de fall där samma nyhetshändelse behandlades av medierna, hade man i mer än hälften av fallen varierat upplägget genom olika intervjuobjekt och olika vinklingar. Men tittar man på vilka ämnen medierna rapporterar om är det däremot mer likriktat. I alla medier utgjorde politik den största kategorin, tätt följd av ekonomi, sysselsättning och brott. Gällande den sistnämnda kategorin fanns det emellertid olikheter medierna emellan. Medan 17 procent av tidningen Ålands nyheter tog sig an brott var motsvarande andel i Ålands Radio bara fem procent. Tidningen Åland hade också överlägset flest unika brottsnyheter, 16 procent, vilket är en stor andel i jämförelse med Nya Åland som bara hade tre procent egna brottsnyheter och med Ålands Radio som inte hade en enda egen brottsnyhet. Reformerna som ägde rum på marknaden mellan 2007 och 2008 påverkade inte nyhetsutbudet dramatiskt. De unika nyheternas andel sjönk en aning medan de gemensamma nyheterna blev fler

Evaluating the Relationship Between Depression, Perceived Stress, Sleep Quality, and Lure Discrimination

Depression, Stress and disordered sleep have been found to negatively affect cognition. However, the specific mechanisms affected are still unclear. These clinical symptoms are all independently associated with the hippocampus, where a memory process called pattern separation is assumed to occur. The current study aimed to further investigate the association between depression and pattern separation by further examining the role that sleep and stress play in this relationship. This study is an expansion from Shelton and Kirwan (2013) where they used the Mnemonic Similarities Task to evaluate lure discrimination and depression. I expanded on this by also evaluating sleep quality and perceived stress. These data were assessed using depression, sleep, and stress as predictors in a regression model to predict lure discrimination. The overall model was not significant. Depression and sleep were both significant main effects and the results in regards to anti-depressant use warrant further investigation. Limitations and future directions are discussed

The Hnau Creatures of C.S. Lewis

Discusses various species in the Space Trilogy considered to be “hnau,” or rational beings: the eldila, sorns, hrossa, and pfifltriggi. Compares this treatment of rationality and self-awareness with the Talking Beasts of Narnia in The Magician’s Nephew and The Last Battle. Concludes that Lewis’s purpose is to show Man’s interconnectedness with, and responsibility for, the rest of creation

Was 49b: An Overmassive AGN in a Merging Dwarf Galaxy?

We present a combined morphological and X-ray analysis of Was 49, an isolated, dual AGN system notable for the presence of a dominant AGN Was 49b in the disk of the primary galaxy Was 49a, at a projected radial distance of 8 kpc from the nucleus. Using X-ray data from Chandra, NuSTAR, and Swift, we find that this AGN has a bolometric luminosity of L_bol ~ 2 x 10^45 erg/s, with a black hole mass of M_BH=1.3^{+2.9}_{-0.9} x 10^8 M_Sol. Despite its large mass, our analysis of optical data from the Discovery Channel Telescope shows that the supermassive black hole is hosted by a stellar counterpart with a mass of only 5.6^{+4.9}_{-2.6} x 10^9 M_Sol, making the SMBH potentially larger than expected from SMBH-galaxy scaling relations, and the stellar counterpart exhibits a morphology that is consistent with dwarf elliptical galaxies. Our analysis of the system in the r and K bands indicates that Was 49 is a minor merger, with a mass ratio of Was 49a to Was 49b between 1:7 and 1:15. This is in contrast with findings that the most luminous merger-triggered AGNs are found in major mergers, and that minor mergers predominantly enhance AGN activity in the primary galaxy.Comment: 11 pages, 6 figures, accepted for publication in Ap