Bayesian Forecast Combination for VAR Models

We consider forecast combination and, indirectly, model selection for VAR models when there is uncertainty about which variables to include in the model in addition to the forecast variables. The key dierence from traditional Bayesian variable selection is that we also allow for uncertainty regarding which endogenous variables to include in the model. That is, all models include the forecast variables, but may otherwise have diering sets of endogenous variables. This is a dicult problem to tackle with a traditional Bayesian approach. Our solution is to focus on the forecasting performance for the variables of interest and we construct model weights from the predictive likelihood of the forecast variables. The procedure is evaluated in a small simulation study and found to perform competitively in applications to real world data.Bayesian model averaging; Predictive likelihood; GDP forecasts

Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the Sgr A complex

We observed OH, H$_2$O, HN$_3$, C$^{18}$O, and C$_I$ towards the +50 km/s cloud (M-0.02-0.07), the CND and the +20 km/s (M-0.13-0.08) cloud in the Sgr A complex with the VLA, Odin and SEST. Strong OH absorption, H$_2$O emission and absorption lines were seen at all three positions. Strong C$^{18}$O emissions were seen towards the +50 and +20 km/s clouds. The CND is rich in H$_2$O and OH, and these abundances are considerably higher than in the surrounding clouds, indicating that shocks, star formation and clump collisions prevail in those objects. A comparison with the literature reveals that it is likely that PDR chemistry including grain surface reactions, and perhaps also the influences of shocks has led to the observed abundances of the observed molecular species studied here. In the redward high-velocity line wings of both the +50 and +20 km/s clouds and the CND, the very high H$_2$O abundances are suggested to be caused by the combined action of shock desorption from icy grain mantles and high-temperature, gas-phase shock chemistry. Only three of the molecules are briefly discussed here. For OH and H$_2$O three of the nine observed positions are shown, while a map of the C$^{18}$O emission is provided. An extensive paper was recently published with Open Access (Karlsson et al. 2013; http://www.aanda.org/articles/aa/pdf/2013/06/aa20471-12.pdf ).Comment: Proc. of a Conf. on IAU Symposium No.303: The Galactic Center: Feeding and Feedback in a Normal Galactic Nucleus 2013, Santa Fe, NM (USA

The Promise of Patent-Backed Finance for Smes and Universities, and Shifting Patent Eligible Subject Matter

This Article reviews and addresses some of the problems concerning adequate capital to develop patented inventions and products, and inhibiting the widespread use of patents to raise financing. The Article divides the IP finance market into three separate, but interrelated markets and analyzes problems, including U.S. patent-eligible subject matter doctrine, within those markets impeding patent backed financing. The Article provides numerous proposals, some of which are in the literature, and calls for additional research for addressing the issues

Aspects of Fatigue Failure Mechanisms in Polymer Fuel Cell Membranes

The swelling-driven fatigue behavior of polymer fuel cell membranes during relative humidity (RH) cycling is investigated. In particular, swelling-induced membrane stresses are obtained from a numerical model simulating fuel cell RH cycle tests, and compared to the lifetimes obtained experimentally from tests conducted in the absence of electrochemical effects. A strong correlation between the lifetimes of the membranes in the actual tests and model results is obtained. In general, higher RH (or swelling) amplitude results in larger stress amplitudes and shorter lifetime, that is, fewer cycles to failure. Tensile stresses are needed for forming local cavities in the membrane, which may eventually lead to craze formation. Cavitation is less likely to occur in compressed membrane at high humidities. The stress–lifetime plots for polymer fuel cell membranes exhibit similar features to those observed for other polymers. The crazing criterion for polymers suggests that craze initiation during RH cycling is more likely to occur in the low compression regions, such as under the channels, which is in agreement with experimental observations. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1506–1517, 201

Structure-Property Relationship in Ionomer Membranes

Perfluorosulfonic acid (PFSA) ionomer membranes are ion-conducting polymers with high water sorption capacity and thermo-mechanical stability. The morphology of PFSA changes during sorption affecting the mechanical and physical properties of the membrane. In this work, we investigate the structure-property relationship in swollen PFSA membranes using three proposed nanostructural descriptions and determine Young\u27s modulus of the membrane at a wide range of temperatures (−20–85°C) and water volume fractions (0–0.5) for these configurations. Comparing the mechanics-based models with experimental data we propose that ion-rich water domains in PFSA membrane are spherical at low water content, spherical with connecting channels at intermediate water content and cylindrical at high water contents. Furthermore, our findings indicate that the scaling behavior for Young\u27s modulus of PFSA ionomers is similar to that of aerogels. This suggests, from a mechanics perspective, that aerogels and ionomers may have a similar interconnected porous nanostructure where some solid regions do not contribute to the mechanical load-bearing capacity

Inget Eldorado, men fenomenalt ändå - Internet som journalistiskt hjälpmedel på de finlandssvenska redaktionerna

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.I avhandlingen utreds hurdan betydelse Internet, och då framförallt WWW och e-post, har fått för finlandssvenska journalister, som hjälpmedel i deras arbete. Utgångspunkten har varit att undersöka om Internet har hunnit bli ett lika viktigt verktyg på Svenskfinlands redaktioner, som det enligt forskningen är utomlands. Attityden är i grunden skeptisk – innehållet i media har inte blivit speciellt mycket annorlunda sedan nätets intåg. Vad kan då en finlandssvensk journalist egentligen ha för nytta av nätet, varför är de flesta så intresserade av det? I texten diskuteras olika slag av insamling av journalistiskt material med hjälp av nätet – oftast är det lika med sökning av information på WWW, men också bland annat intervjuer via e-post och sökning efter bild- och ljudmaterial. Källkritik behandlas skilt, eftersom det är en central fråga när man diskuterar information från nätet och speciellt WWW. Som teoretisk bakgrund har använts främst Ari Heinonens Journalism in the Age of the Net – Changing Society, Changing Profession (1999), Don Middlebergs och Steven Ross’ utredningar från 2000 och 2001, samt Timo Lüges Usage Patterns and Information Needs of Journalists on the Internet. An Empirical Study at USUS – the Usually Useful Internet Guide for Journalist (1999). Både kvantitativa och kvalitativa metoder har använts i den egna forskningen. Dels baserar sig resultaten på en traditionell enkät, som gick ut till samtliga finlandssvenska dagstidningar hösten 1999, och dels på tio kompletterande kvalitativa intervjuer med etermediejournalister från våren och hösten 2001. Resultaten visar främst att Internet under några år snabbt har hunnit etablera sig som ett av de mest använda journalistiska hjälpmedlen också i Svenskfinland. Nätet är inte orsak till någon större förändring av innehållet i media, men det är flexibelt och till stor hjälp med mängder av mindre saker – kontaktuppgifter, bakgrundsinformation, i viss mån nya uppslag (i den mån journalistens samvete tillåter det), och mycket annat. Allt det här anses numera vara lättare eller snabbare än tidigare, och det är tillräckligt mycket för att slutsatsen av forskningen skall vara att Internet idag verkligen är ett av mest användbara verktygen som står till en journalists tjänst, tillsammans med telefonen, den bärbara inspelningsutrustningen och ordbehandlaren

A many-body approach to transport in quantum systems : from the transient regime to the stationary state

We review one of the most versatile theoretical approaches to the study of time-dependent correlated quantum transport in nano-systems: the non-equilibrium Green's function (NEGF) formalism. Within this formalism, one can treat, on the same footing, inter-particle interactions, external drives and/or perturbations, and coupling to baths with a (piece-wise) continuum set of degrees of freedom. After a historical overview on the theory of transport in quantum systems, we present a modern introduction of the NEGF approach to quantum transport. We discuss the inclusion of inter-particle interactions using diagrammatic techniques, and the use of the so-called embedding and inbedding techniques which take the bath couplings into account non-perturbatively. In various limits, such as the non-interacting limit and the steady-state limit, we then show how the NEGF formalism elegantly reduces to well-known formulae in quantum transport as special cases. We then discuss non-equilibrium transport in general, for both particle and energy currents. Under the presence of a time-dependent drive-encompassing pump-probe scenarios as well as driven quantum systems-we discuss the transient as well as asymptotic behavior, and also how to use NEGF to infer information on the out-of-equilibrium system. As illustrative examples, we consider model systems general enough to pave the way to realistic systems. These examples encompass one- and two-dimensional electronic systems, systems with electron-phonon couplings, topological superconductors, and optically responsive molecular junctions where electron-photon couplings are relevant.Peer reviewe