Monads in Double Categories

We extend the basic concepts of Street's formal theory of monads from the setting of 2-categories to that of double categories. In particular, we introduce the double category Mnd(C) of monads in a double category C and define what it means for a double category to admit the construction of free monads. Our main theorem shows that, under some mild conditions, a double category that is a framed bicategory admits the construction of free monads if its horizontal 2-category does. We apply this result to obtain double adjunctions which extend the adjunction between graphs and categories and the adjunction between polynomial endofunctors and polynomial monads.Comment: 30 pages; v2: accepted for publication in the Journal of Pure and Applied Algebra; added hypothesis in Theorem 3.7 that source and target functors preserve equalizers; on page 18, bottom, in the statement concerning the existence of a left adjoint, "if and only if" was replaced by "a sufficient condition"; acknowledgements expande

Double Adjunctions and Free Monads

We characterize double adjunctions in terms of presheaves and universal squares, and then apply these characterizations to free monads and Eilenberg--Moore objects in double categories. We improve upon our earlier result in "Monads in Double Categories", JPAA 215:6, pages 1174-1197, 2011, to conclude: if a double category with cofolding admits the construction of free monads in its horizontal 2-category, then it also admits the construction of free monads as a double category. We also prove that a double category admits Eilenberg--Moore objects if and only if a certain parameterized presheaf is representable. Along the way, we develop parameterized presheaves on double categories and prove a double-categorical Yoneda Lemma.Comment: 52 page

B -> D* at zero recoil revisited

We examine the B -> D* form factor at zero recoil using a continuum QCD approach rooted in the heavy quark sum rules framework. A refined evaluation of the radiative corrections as well as the most recent estimates of higher order power terms together with more careful continuum calculation are included. An upper bound on the form factor of F(1)< 0.93 is derived, based on just the positivity of inelastic contributions. A model-independent estimate of the inelastic contributions shows they are quite significant, lowering the form factor by about 6% or more. This results in an unbiased estimate F(1) \approx 0.86 with about three percent uncertainty in the central value.Comment: 9 pages, 3 figures

Understanding of plasticizer effect on the temperature dependence of mechanical and dielectric relaxation function of polymers of interest for tire formulation.

168 p.Las propiedades dinámicas de los elastómeros en régimen lineal son una de las líneas de investigación centrales de Michelin. La comprensión del efecto del plastificante en la dependencia en temperatura de la relajación mecánica es un punto clave para mejorar el rendimiento de un neumático, en particular aumentar la adherencia durante el frenado y la disminución de la resistencia a la rodadura. De hecho, durante su período de uso, el neumático debe disipar la mayor cantidad de energía posible durante el frenado, sin embargo, debemos minimizar este proceso durante el rodamiento regular. Variar la temperatura de transición vítrea (Tg) del sistema permite modificar el dominio de la frecuencia y la temperatura en el que el material disipa la energía. Los resultados obtenidos en esta tesis doctoral permiten obtener una mejor comprensión de la dinámica de las mezclas de polímeros, así como la predicción de las propiedades mecánicas de alta frecuencia que podrían ser un punto determinante para facilitar una mejora significativa en el diseño de materiales con propiedades deseadas.CFM :Materials Physics Center Micheli

Understanding of plasticizer effect on the temperature dependence of mechanical and dielectric relaxation function of polymers of interest for tire formulation.

168 p.Las propiedades dinámicas de los elastómeros en régimen lineal son una de las líneas de investigación centrales de Michelin. La comprensión del efecto del plastificante en la dependencia en temperatura de la relajación mecánica es un punto clave para mejorar el rendimiento de un neumático, en particular aumentar la adherencia durante el frenado y la disminución de la resistencia a la rodadura. De hecho, durante su período de uso, el neumático debe disipar la mayor cantidad de energía posible durante el frenado, sin embargo, debemos minimizar este proceso durante el rodamiento regular. Variar la temperatura de transición vítrea (Tg) del sistema permite modificar el dominio de la frecuencia y la temperatura en el que el material disipa la energía. Los resultados obtenidos en esta tesis doctoral permiten obtener una mejor comprensión de la dinámica de las mezclas de polímeros, así como la predicción de las propiedades mecánicas de alta frecuencia que podrían ser un punto determinante para facilitar una mejora significativa en el diseño de materiales con propiedades deseadas.CFM :Materials Physics Center Micheli

Using the transit of Venus to probe the upper planetary atmosphere

The atmosphere of a transiting planet shields the stellar radiation providing us with a powerful method to estimate its size and density. In particular, because of their high ionization energy, atoms with high atomic number (Z) absorb short-wavelength radiation in the upper atmosphere, undetectable with observations in visible light. One implication is that the planet should appear larger during a primary transit observed in high energy bands than in the optical band. The last Venus transit in 2012 offered a unique opportunity to study this effect. The transit has been monitored by solar space observations from Hinode and Solar Dynamics Observatory (SDO). We measure the radius of Venus during the transit in three different bands with subpixel accuracy: optical (4500A), UV (1600A, 1700A), Extreme UltraViolet (EUV, 171-335A) and soft X-rays (about 10A). We find that, while the Venus optical radius is about 80 km larger than the solid body radius (the expected opacity mainly due to clouds and haze), the radius increases further by more than 70 km in the EUV and soft X-rays. These measurements mark the densest ion layers of Venus' ionosphere, providing information about the column density of CO2 and CO. They are useful for planning missions in situ to estimate the dynamical pressure from the environment, and can be employed as a benchmark case for observations with future missions, such as the ESA Athena, which will be sensitive enough to detect transits of exoplanets in high-energy bands.Comment: 13 pages, 2 figures; published in Nature Communications; the full and copy-edited version is open access at http://www.nature.com/ncomms/2015/150623/ncomms8563/full/ncomms8563.htm

Double adjunctions

We characterize double adjunctions in terms of presheaves and universal squares, and then apply these characterizations to free monads and Eilenberg-Moore objects in double categories. We improve upon an earlier result of Fiore-Gambino-Kock in [7] to conclude: if a double category with cofolding admits the construction of free monads in its horizontal 2-category, then it also admits the construction of free monads as a double category horizontally and vertically, and also in its vertical 2-category. We also prove that a double category admits Eilenberg-Moore objects if and only if a certain parameterized presheaf is representable. Along the way, we develop parameterized presheaves on double categories and prove a double Yoneda Lemma

Monads in double categories

We extend the basic concepts of Street's formal theory of monads from the setting of 2-categories to that of double categories. In particular, we introduce the double category Mnd(C) of monads in a double category C and de ne what it means for a double category to admit the construction of free monads. Our main theorem shows that, under some mild conditions, a double category that is a framed bicategory admits the construction of free monads if its horizontal 2-category does. We apply this result to obtain double adjunctions which extend the adjunction between graphs and categories and the adjunction between polynomial endofunctors and polynomial monads

Constraints on Light Bottom Squarks from Radiative B-Meson Decays

The presence of a light b-squark (with mass about 4 GeV) and gluino (with mass about 15 GeV) might explain the observed excess in b-quark production at the Tevatron. Though provocative, this model is not excluded by present data. The light supersymmetric particles can induce large flavor-changing effects in radiative decays of B mesons. We analyse the decays B->X_s gamma and B->X_{sg} in this scenario and derive restrictive bounds on the flavor-changing quark-squark-gluino couplings.Comment: 14 pages, 3 figures. One reference added. Final version published in Physics Letters