Geodesic Diagrams, Gravitational Interactions & OPE Structures

We give a systematic procedure to evaluate conformal partial waves involving symmetric tensors for an arbitrary CFT$_d$ using geodesic Witten diagrams in AdS$_{d+1}$. Using this procedure we discuss how to draw a line between the tensor structures in the CFT and cubic interactions in AdS. We contrast this map to known results using three-point Witten diagrams: the maps obtained via volume versus geodesic integrals differ. Despite these differences, we show how to decompose four-point exchange Witten diagrams in terms of geodesic diagrams, and we discuss the product expansion of local bulk fields in AdS.Comment: typos corrected, references adde

La técnica compositiva en las cantinelas de Santa Eulalia en latín y francés : estudio comparativo

This essay presents a new view of the two poems by Saint Eulalia found in the famous Saint Amand manuscript, today in the collections of the Valenciennes Library. Both poems are of unusual interest: the first, written in French, constitutes the first vernacular poem conserved; the second, composed in Latin, raises questions about literary genre. The comparative study to follow emphasizes a similarity in the two poems' technique and determines their authorship. Assuming that the poems date from the last third of the ninth century, the essay establishes, in addition, a relationship between Saint Eulalia's writing and the larger poetical and musical revolution then taking place in the region of the old French kingdom delimited by the Jumiéges, Réomé, and Saint Amand abbeys.Este ensayo presenta una nueva perspectiva sobre los dos poemas de Santa Eulalia en el famoso manuscrito de San Amand, que se encuentra actualmente en la colección de la Biblioteca de Valenciennes. Ambos poemas son inusuales: el primero, escrito en francés, es el primer poema vernáculo que se conserva. El segundo, escrito en latín, provoca preguntas acerca del género literario. El estudio comparativo que sigue enfatiza en la similitud en la técnica empleada en ambos poemas, determinando su autoría. Asumiendo que los poemas datan del último tercio del siglo noveno, este ensayo establece, además, una relación entre la escritura de Santa Eulalia y la gran revolución poética y musical que tomó lugar en la región del antiguo Reino de Francia colindante con Jumiéges, Réomé, y las abadías de Santa Amand abbeys

Evolution of corporate credit rating standards from 2002 to 2016

Alp (2013) studies how corporate credit ratings’ standards change from 1985 to 2007. The author analyzes a structural break in criteria employed by credit rating agencies (CRAs) around the 2002 financial scandals. I draw a pararell to the Great Recession. In 2008, CRAs take the fall as some financial instruments are not subject to a proper credit assessment. I analyze whether corporate credit ratings are affected after the most recent crises: the DotCom Bubble and the 2008 Financial Crisis. I regress corporate credit ratings on firm fundamentals and year indicators to evaluate how they change from 2002 to 2016. I observe a trend of stringent standards for the entire sample, when compared to 2002. During the Great Recession, corporations are assigned credit ratings that are 0.75 notches lower than in 2002, suggesting an average one­notch downgrade, controlling for firm’s characteristics. I find that, overall, CRAs become less strict after 2009. It should be noted that, in 2016, the standards employed are still less lenient than in 2002, indicating a conservative approach. I split the sample into investment­ and speculative­ grade observations. Standards for investment­grade ratings remain stringent even after the Great Recession, in comparison to 2002, although to a lesser degree. Following the DotCom Bubble, speculative­grade firms experience a steep decline in ratings. After 2009, these companies quickly rebound and are subject to looser standards. Overall, the years of the Great Recession are marked by lower credit ratings, which is confirmed by structural break tests.Alp (2013) estuda como os critérios de classificação do risco de crédito evoluem de 1985 a 2007. O autor analisa uma mudança estrutural nos critérios das agências de crédito na altura dos escândalos financeiros de 2002. Eu traço um paralelo com a Grande Recessão de 2008. As agências de crédito são consideradas parcialmente culpadas pois vários instrumentos financeiros não foram sujeitos a uma avaliação de risco adequada. Eu analiso se as classificações são afetadas após as crises mais recentes: a de 2002 e a de 2008. Regresso classificações do risco de crédito como função de características da empresa e indicadores de ano para avaliar como mudam de 2002 a 2016. Observo uma tendência de padrões mais rigorosos para a amostra total, comparando a 2002. Durante a Grande Recessão, são atribuídas classificações inferiores em 0.75 às de 2002, sugerindo uma descida média de uma classificação com as mesmas características. Os critérios tornam­se menos rigorosos após 2009. Os padrões em 2016 ainda são mais apertados que em 2002, indicando uma abordagem conservadora. Divido a amostra em observações de grau de investimento e especulativo. As normas de grau de investimento permanecem rigorosas mesmo após a Grande Recessão, em comparação a 2002, embora em menor escala. Após 2002, as empresas de grau especulativo sofrem um declínio acentuado nas classificações. Depois de 2009, estes negócios recuperam rapidamente e são sujeitos a critérios mais relaxados. No geral, os anos da Grande Recessão são marcados por classificações de crédito mais baixas, confirmado por testes de mudança estrutural

Dortmunder U and Union Quarter - The Role of Meanwhile Uses in Urban Regeneration

This report is part of the T-Factor project Advanced Case Studies Portfolio. It introduces the case of the urban regeneration of "Rheinische Staße" in Dortmund as well as the revitalisation of Dortmunder U with the purpose of investigating the role of meanwhile/temporary uses in urban planning. The report presents a comprehensive overview of the context, chronology, stakeholders, results, impacts, and critical elements pertaining to each of the meanwhile uses that occurred during the urban regeneration in the Union Quarter (Rheinische Straße and Dortmunder U)

Accurate measurement of the specific absorption rate using a suitable adiabatic magnetothermal setup

3 pages, 3 figures.Accurate measurements of the specific absorption rate (SAR) of solids and fluids were obtained by a calorimetric method, using a special-purpose setup working under adiabatic conditions. Unlike in current nonadiabatic setups, the weak heat exchange with the surroundings allowed a straightforward determination of temperature increments, avoiding the usual initial-time approximations. The measurements performed on a commercial magnetite aqueous ferrofluid revealed a good reproducibility (4%). Also, the measurements on a copper sample allowed comparison between experimental and theoretical values: adiabatic conditions gave SAR values only 3% higher than the theoretical ones, while the typical nonadiabatic method underestimated SAR by 21%.Financial support from the Spanish MEC (Project No. MAT2004-03395-C02-02) is acknowledged. Eva Natividad thanks the Spanish CSIC for her I3P Contract (European Social Fund).Peer reviewe

Accurate measurement of the specific absorption rate using a suitable adiabatic magnetothermal setup

3 pages, 3 figures.Accurate measurements of the specific absorption rate (SAR) of solids and fluids were obtained by a calorimetric method, using a special-purpose setup working under adiabatic conditions. Unlike in current nonadiabatic setups, the weak heat exchange with the surroundings allowed a straightforward determination of temperature increments, avoiding the usual initial-time approximations. The measurements performed on a commercial magnetite aqueous ferrofluid revealed a good reproducibility (4%). Also, the measurements on a copper sample allowed comparison between experimental and theoretical values: adiabatic conditions gave SAR values only 3% higher than the theoretical ones, while the typical nonadiabatic method underestimated SAR by 21%.Financial support from the Spanish MEC (Project No. MAT2004-03395-C02-02) is acknowledged. Eva Natividad thanks the Spanish CSIC for her I3P Contract (European Social Fund).Peer reviewe

Adiabatic magnetothermia makes possible the study of the temperature dependence of the heat dissipated by magnetic nanoparticles under alternating magnetic fields

3 páginas, 5 figuras.Determining the low-temperature dependence of the specific absorption rate (SAR) of magnetic nanoparticles under alternating magnetic fields with amplitudes and frequencies similar to those used in applications such as magnetic fluid hyperthermia, becomes essential when theoretical expressions fail to extrapolate the behavior of nanoparticle arrangements. We prove that adiabatic magnetothermia is capable of providing SAR(T) data displaying an excellent continuity with those obtained from magnetic measurements at lower ac-field amplitudes and frequencies.This work has been funded by the Spanish MICINN and FEDER, projects, Grant No. MAT2007-61621 and CONSOLIDER-INGENIO in Molecular Nanoscience, Grant No. CSD 2007-00010.Peer reviewe

Roughness indices and estimation of temporal depressional storage in a cropped land

[Abstract] Soil surface roughness is considered an important parameter which affects hydraulic properties of the soil surface. The evaluation of maximum water depressional storage (MDS), i.e. the absolute volume of water which can be stored at a rough surface before water runoff starts, will improve the results of overland flow modelling at a catchment scale. An amount of 25 roughness measurements in a cropped land were measured from December 1998 to May 1999 after mouldboard plough. A pinmeter was used for elevation measurements using a 2 cm x 2 cm grid on ca. 1.80 m 2 plots. Four roughness indices: random roughness, limiting elevation, limiting slope and tortuosity were calculated. Subsequently the temporary water retention was estimated. MDS showed a great variability ranging from 1.76 l/m2 to 20.36 l/m2