Projectivity of Planar Zeros in Field and String Theory Amplitudes

We study the projective properties of planar zeros of tree-level scattering amplitudes in various theories. Whereas for pure scalar field theories we find that the planar zeros of the five-point amplitude do not enjoy projective invariance, coupling scalars to gauge fields gives rise to tree-level amplitudes whose planar zeros are determined by homogeneous polynomials in the stereographic coordinates labelling the direction of flight of the outgoing particles. In the case of pure gauge theories, this projective structure is generically destroyed if string corrections are taken into account. Scattering amplitudes of two scalars with graviton emission vanish exactly in the planar limit, whereas planar graviton amplitudes are zero for helicity violating configurations. These results are corrected by string effects, computed using the single-valued projection, which render the planar amplitude nonzero. Finally, we discuss how the structure of planar zeros can be derived from the soft limit behavior of the scattering amplitudes.Comment: 39 page, 5 figures. v2: typos corrected. It matches the version published in Journal of High Energy Physic

Assessing success of forest restoration efforts in degraded montane cloud forests in southern Mexico

Montane cloud forests are home to great biodiversity. However, non-sustainable anthropogenic activities have led to the loss of forest cover in southern Mexico. Increasing conservation, restoration and sustainable use of forest resources prevents the loss of cloud forests. In this study, success of forest restoration was evaluated in a degraded forest of Highlands Chiapas. The goal of this study was to assess the structure and composition of native tree species. We evaluated vegetation composition at three sites that had undergone enrichment plantings. Floristic composition and structure of the herbaceous, seedling, sapling, and overstory layers were measured. A total of sixty-six native tree species were recorded. Enrichment planting was found to have increased tree diversity. Moreover, 54% of the planted species were found in the understory, indicating that they were successfully recruiting. In conclusion, enrichment planting can aid in the conservation of forest cover in degraded areas

Powering AGNs with super-critical black holes

We propose a novel mechanism for powering the central engines of Active Galactic Nuclei through super-critical (type II) black hole collapse. In this picture, ~$10^3 M_\odot$ of material collapsing at relativistic speeds can trigger a gravitational shock, which can eject a large percentage of the collapsing matter at relativistic speeds, leaving behind a "light" black hole. In the presence of a poloidal magnetic field, the plasma collimates along two jets, and the associated electron synchrotron radiation can easily account for the observed radio luminosities, sizes and durations of AGN jets. For Lorentz factors of order 100 and magnetic fields of a few hundred $\mu G$, synchrotron electrons can shine for $10^6$ yrs, producing jets of sizes of order 100 kpc. This mechanism may also be relevant for Gamma Ray Bursts and, in the absence of magnetic field, supernova explosions.Comment: 4 pages, 1 figur

“HISTORIA E IMPACTO TURÍSTICO DE LA FERIA DEL REBOZO EN TENANCINGO, ESTADO DE MÉXICO, 2012”

La presente investigación lleva por título “Historia e Impacto Turístico de la Feria del Rebozo en Tenancingo, Estado de México 2012”, motivo por el cual se realizó una reflexión conceptual de términos integrados como turismo, patrimonio, cultura, patrimonio cultural, identidad cultural, artesanías, tipos de artesanías, textiles, rebozo, feria, entre otros, lo que permitió mostrar la importancia de los conceptos y el potencial turístico que tiene la Feria del Rebozo, que es el objeto de estudio dentro de esta investigación. De igual forma la investigación se sustentó bajo la metodología estadística del Paquete Estadístico “SPSS” que es el Paquete Estadístico para las Ciencias Sociales, el cual mide matemáticamente los fenómenos sociales, para analizar sus relaciones y así llegar a generalizaciones sobre su naturaleza y significado. Partiendo del supuesto de que los datos cualitativos pueden ser convertidos en términos cuantitativos…” (García, 2006; p.11). Dicho método comprendió la aplicación de una encuesta que fue aplicada a los turistas y a la gente local que participan en la Feria del Rebozo. Para la construcción de la encuesta se basó en la metodología sugerida por Roberto Hernández Sampieri, (2003; p.45) para lo cual se utilizó un escalamiento tipo Likert para validar el instrumento y de esta manera determinar el Impacto Turístico de la Feria del Rebozo en Tenancingo. Respecto a la presentación del documento están los antecedentes de las ferias, seguido de la justificación, hipótesis, objetivos y la metodología aplicada dentro de esta investigación, de igual manera los resultados de la investigación se encuentran plasmados y consta de tres capítulos, los que a continuación se describen brevemente. Para el Capítulo I en primer lugar se expone el Marco Referencial, donde se habla de aspectos relacionados con Turismo, Modalidades del Turismo, Patrimonio, Cultura, Patrimonio Cultural, Identidad Cultural, Artesanías, Tipos de Artesanías, Rebozo, Producto, Producto Turístico, entre algunos otros aspectos teóricos que fundamentan y regulan la investigación. Dentro del Capítulo II, se habla de la Feria del Rebozo en Tenancingo, empezando por las generalidades del municipio de Tenancingo, seguido de La Feria del Rebozo, así como de la Organización de Feria, Personas que acuden a la Feria y por último Personas que participan en la Feria. Toda esta información permitió conocer a grandes rasgos todo lo que implica la Feria del rebozo en Tenancingo. En el Capítulo III, siendo este el último capítulo, se presentan los resultados de la investigación de campo sobre la Feria del Rebozo en Tenancingo, mostrando las gráficas que permiten observar resultados significativos obtenidos de las encuestas aplicadas en la Feria del Rebozo en Tenancingo 2012 y de las cuales se obtuvieron conclusiones. Posteriormente se presentan las conclusiones y propuestas. Por último se integran los anexos y la bibliografía utilizada en la investigación. Cabe mencionar que dentro de esta investigación se recurrió a la consulta de diferentes investigadores como lo fueron: Miguel Ángel Acerenza, Roberto Boullón, Fabio Cárdenas, Roberto Ebersole, Enrique Florescano, Madeleine Grawitz, entre algunos otros, para de esta forma realizar un trabajo integral que llevó a obtener un resultado más preciso

Association of occult chronic kidney disease with cardiovascular risk and their risk factors in university workers

Occult chronic kidney disease (OCKD) and cardiovascular risk (CVR) share risk factors that trigger chronic degenerative diseases. Aim. To assess the association of OCKD with CVR and its risk factors in a sample of university workers. Material and methods. This is a crosssectional study. From 89 volunteers the lipid profile, glucose, urea, creatinine and uric acid were obtained from blood as well as anthropometric measures and blood pressure. They were classified by their CVR calculated by the Framingham equation, into the groups: with-CVR and without-CVR; and by their glomerular filtration rate (GFR) into: with-OCKD and without-OCKD. Then into subgroups of each CVR factor (CVRF): sex, smoking, diabetes mellitus (DM) and hypertension. The statistical differences between groups (p <0.05) and the correlation between CVR and GFR and the odds ratio (OR) for each CVRF were determined. Results. A negative correlation between the OCKD and the CVR was obtained for men (p = - 0.743, p = 0.000) and women (p = - 0.874, p = 0.000). The overall prevalence of hypertension was 23.6% (OR = 15.43 for CVR, 95% CI, 4.04 - 58.95, OR = 14.75 for OCKD, 95% CI 2.76 - 78.23) and older than 50 years of 33.7% (OR for CVR = 20.37, 95% CI, 6.25 - 66.43). Conclusions. OCKD is strongly associated with the CVR. Furthermore, each CVRF impacts in different range and level to the development of cardiovascular disease and kidney failure