Direct multiscale coupling of a transport code to gyrokinetic turbulence codes

Direct coupling between a transport solver and local, nonlinear gyrokinetic calculations using the multiscale gyrokinetic code TRINITY [M. Barnes, Ph.D. thesis, arxiv:0901.2868] is described. The coupling of the microscopic and macroscopic physics is done within the framework of multiscale gyrokinetic theory, of which we present the assumptions and key results. An assumption of scale separation in space and time allows for the simulation of turbulence in small regions of the space-time grid, which are embedded in a coarse grid on which the transport equations are implicitly evolved. This leads to a reduction in computational expense of several orders of magnitude, making first-principles simulations of the full fusion device volume over the confinement time feasible on current computing resources. Numerical results from TRINITY simulations are presented and compared with experimental data from JET and ASDEX Upgrade plasmas.Comment: 12 pages, 13 figures, invited paper for 2009 APS-DPP meeting, submitted to Phys. Plasma

Fermion Masses and Mixing in Four and More Dimensions

We give an overview of recent progress in the study of fermion mass and flavor mixing phenomena. Mass matrix ansatze are considered within the SM and SUSY GUTs where some predictive frameworks based on SU(5) and SO(10) are reviewed. We describe a variety of schemes to construct quark mass matrices in extra dimensions focusing on four major classes: models with the SM residing on 3-brane, models with universal extra dimensions, models with split fermions and models with warped extra dimensions. We outline how realistic patterns of quark mass matrices could be derived from orbifold models in heterotic superstring theory. Finally, we address the fermion mass problem in intersecting D-branes scenarios, and present models with D6-branes able to give a good quantitatively description of quark masses and mixing. The role of flavor/CP violation problem as a probe of new physics is emphasized.Comment: a review based on seminars presented by S.K. in different places, 34 pages, late

Numerical Simulations of High Redshift Star Formation in Dwarf Galaxies

We present first results from three-dimensional hydrodynamic simulations of the high redshift formation of dwarf galaxies. The simulations use an Eulerian adaptive mesh refinement technique to follow the non-equilibrium chemistry of hydrogen and helium with cosmological initial conditions drawn from a popular Lambda-dominated CDM model. We include the effects of reionization using a uniform radiation field, a phenomenological description of the effect of star formation and, in a separate simulation, the effects of stellar feedback. The results highlight the effects of stellar feedback and photoionization on the baryon content and star formation of galaxies with virial temperatures of approximately 10^4K. Dwarf sized dark matter halos that assemble prior to reionization are able to form stars. Most halos of similar mass that assemble after reionization do not form stars by redshift of three. Dwarf galaxies that form stars show large variations in their gas content because of stellar feedback and photoionization effects. Baryon-to-dark matter mass ratios are found to lie below the cosmic mean as a result of stellar feedback. The supposed substructure problem of CDM is critically assessed on the basis of these results. The star formation histories modulated by radiative and stellar feedbacks are discussed. In addition, metallicities of individual objects are shown to be naturally correlated with their mass-to-light ratios as is also evident in the properties of local dwarf galaxies.Comment: 27 pages, 8 figures, accepted for publication in Ap

La pandemia de gripe de 1918–1919 en Bogotá y Boyacá, 91 años después

ResumenIntroducciónLa pandemia de gripa de 1918–1919 causó la mayor mortalidad en la historia en corto tiempo. Se estima que entre 20 millones y 50 millones de personas fallecieron en menos de un año. Los historiadores de Europa y Estados Unidos registran tres oleadas, con mayor impacto en octubre y noviembre (80% de la mortalidad), que afectaron la población económicamente activa. La gripa nos ha acompañado en América desde el segundo viaje de Colón, probablemente asociada a la importación de cerdos y caballos infectados.Materiales y métodosSe describen las condiciones sociales y de salud en Bogotá y Boyacá, a partir de fuentes documentales de la época. Las tasas de mortalidad se calcularon a partir de los registros de la Iglesia.ResultadosLas condiciones de pobreza y hacinamiento acentuaron la letalidad. La iniciativa privada asumió el control y la atención de las víctimas, dada la ineficiencia de las auautoridades. Se recolectaron 106.484 registros de defunción del periodo 1912–1927, 9,5% (10.123 muertes) por gripa. Entre octubre y noviembre de 1918, hubo 2.019 muertes en Boyacá, con una tasa de 4,8 por 1.000 habitantes, y predominio en menores de 5 años y en ancianos; no se observaron oleadas. La mayor altura sobre el nivel del mar resultó ser un factor de riesgo para la muerte por gripa.DiscusiónLas condiciones actuales favorecen una nueva pandemia. Los nuevos medios de transporte podrían aumentar la velocidad de transmisión de la infección. Se hace necesario conocer el pasado y las implicaciones en la mortalidad para evitar repetir los errores en el futuro.AbstractIntroductionThe pandemic Flu of 1918–19 was the cause of the greatest mortality in history, in a very short period of time. An estimated mortality between 20 and 50 million deaths/year was calculated. The European and American researchers registered three different epidemic peaks, with a special impact between October and November (80% mortality), affecting a large proportion of the economically active population. Since Colombo's second travel, the Flu has been within us, probably associated with the presence infected pigs and horses, brought by the Spaniards.Materials and methodsWe describe the social and health conditions in Bogotá and Boyacá, from documentary sources of the time. Mortality rates were estimated from Church records.ResultsPoverty and overcrowding conditions increased the epidemic lethality. As a result of the inefficiency of the authorities of that time, the control and care of victims were assumed by private organizations. We collected 106,484 records from death certificates, since 1912 until 1927; 9.5% (10,123 deaths) were caused by flu. The mortality rate attributed to the Flu was 4.8 per 1,000 people (2,019 deaths) between October and November of 1918. Children under 5 years and the elder people were mainly affected by Flu. The highest altitude above sea level was a risk factor for Flu mortality and non epidemic waves were observed.DiscussionDue to current general conditions, a new epidemic is possible. New means of transportation may increase its transmission rate. Lessons from the past can lead us to avoid repeating same mistakes in the future

Direct Mediation and Metastable Supersymmetry Breaking for SO(10)

We examine a metastable $\mathcal{N}=1$ Macroscopic SO(N) SQCD model of Intriligator, Seiberg and Shih (ISS). We introduce various baryon and meson deformations, including multitrace operators and explore embedding an SO(10) parent of the standard model into two weakly gauged flavour sectors. Direct fundamental messengers and the symmetric pseudo-modulus messenger mediate SUSY breaking to the MSSM. Gaugino and sfermion masses are computed and compared for each deformation type. We also explore reducing the rank of the magnetic quark matrix of the ISS model and find an additional fundamental messenger.Comment: 43 pages, Latex. Version to appear in JHEP

Solubilities of some new refrigerants in water

Solubility data for the refrigerants HFC23 (CHF3), HFC32 (CH2F2) and HFC125 (C2HF5) in water have been determined as a function of the temperature in the range of temperatures 288-303 K at atmospheric pressure. These hydrofluorocarbons (HFCs) are good substitutes of the chlorofluorocarbons (CFCs), which have significant impact to stratospheric ozone depletion.http://www.sciencedirect.com/science/article/B6TG2-4177PK4-7/1/12019e8daebba6ccc7515753953406a

Yukawa couplings and masses of non-chiral states for the Standard Model on D6-branes on T6/Z6'

The perturbative leading order open string three-point couplings for the Standard Model with hidden USp(6) on fractional D6-branes on T6/Z6' from arXiv:0806.3039 [hep-th], arXiv:0910.0843 [hep-th] are computed. Physical Yukawa couplings consisting of holomorphic Wilsonian superpotential terms times a non-holomorphic prefactor involving the corresponding classical open string Kaehler metrics are given, and mass terms for all non-chiral matter states are derived. The lepton Yukawa interactions are at leading order flavour diagonal, while the quark sector displays a more intricate pattern of mixings. While N=2 supersymmetric sectors acquire masses via only two D6-brane displacements - which also provide the hierarchies between up- and down-type Yukawas within one quark or lepton generation -, the remaining vector-like states receive masses via perturbative three-point couplings to some Standard Model singlet fields with vevs along flat directions. Couplings to the hidden sector and messengers for supersymmetry breaking are briefly discussed.Comment: 52 pages (including 8p. appendix); 5 figures; 14 tables; v2: discussion in section 4.1.3 extended, footnote 5 added, typos corrected, accepted by JHE

Metallicity determination in gas-rich galaxies with semiempirical methods

A study of the precision of the semiempirical methods used in the determination of the chemical abundances in gas-rich galaxies is carried out. In order to do this the oxygen abundances of a total of 438 galaxies were determined using the electronic temperature, the $R_{23}$ and the P methods. The new calibration of the P method gives the smaller dispersion for the low and high metallicity regions, while the best numbers in the turnaround region are given by the $R_{23}$ method. We also found that the dispersion correlates with the metallicity. Finally, it can be said that all the semiempirical methods studied here are quite insensitive to metallicity with a value of $8.0\pm0.2$ dex for more than 50% of the total sample. \keywords{ISM: abundances; (ISM): H {\sc ii} regions}Comment: 26 pages, 9 figures and 2 tables. To appear at AJ, January 200

Teaching vs. Research: Toward the Reconciliation of an Academic Dilemma

A line of thought that compares two major changes in Higher Education and the societal environments surrounding them is presented. A model, currently taking place, associated with the perceived controversy between teaching and research is introduced and discussed. The need to foster appropriate procedures where university constituencies are brought together to participate in the process of reshaping the university model guaranteeing its survivability is recognized. Finally, options for teaching comparable with the scale established for research are proposed as a reconciliatory model to solve this academic dilemma