Potential constrains on Lorentz invariance violation from the HAWC TeV gamma-rays

Astrophysical scenarios provide a unique opportunity to test the possible signatures of Lorentz Invariance Violation (LIV) due to the high energies and the very long distances they involve. An isotropic correction to the photon dispersion relation, by hypothetical Lorentz invariance violation, has a consequence that photons of sufficient energy are unstable and decay very fast. The High Altitude Water Cherenkov (HAWC) observatory is sensitive to gamma-rays in the 100 GeV to 100 TeV energy range, making it a very useful tool to study LIV. In this work we present potential stringent limits for the LIV energy scale at first and second order correction by the potential observations of primary very high energy photons in HAWC energy range.Comment: Presented at the 35th International Cosmic Ray Conference (ICRC2017), Bexco, Busan, Korea. See arXiv:1708.02572 for all HAWC contribution

Effects of Lorentz invariance violation on cosmic ray photon emission and gamma ray decay processes

In this work, we use Lorentz invariance violation (LIV) introduced as a generic modification to particle dispersion relations to study some consequences of single photon emission, known as vacuum Cherenkov radiation, and photon decay processes in cosmic and gamma rays. These processes are forbidden in a Lorentz invariant theory but allowed under the hypothesis of LIV. We show that the emission rate have a dependency on the cosmic ray primary mass and the electric charge that could modify the UHECR spectrum. Furthermore, LIV dramatically enhances photon decay into an electro-positron pair above certain energy threshold. This last effect can then be used to set limits to the LIV energy scale from the direct observation of very high energy cosmic photon events by telescopes of gamma-rays.Comment: Proceedings of the 35th International Cosmic Ray Conference (ICRC 2017), Busan, Kore

Interacciones en el manejo forestal y las prácticas agrícolas en comunidades originarias del Estado de México, México: el modelo de paisajes bioculturales a escala local

La implementación del modelo de paisajes bioculturales a escala local en los pueblos originarios de México podría conducir a la resignificación de dichos paisajes bioculturales, ya que permite la integración de prácticas y saberes para su gestión sostenible. El objetivo de este estudio fue identificar las dimensiones que caracterizan a los aspectos de los paisajes bioculturales, así como las interacciones en el manejo forestal y las prácticas agrícolas en comunidades originarias del Estado de México, México, para relacionarlas con los objetivos a escala local del modelo de paisajes bioculturales. Con un enfoque cualitativo, se realizó un taller participativo dirigido a miembros de Organizaciones No Gubernamentales (ONG) y académicos especialistas en el tema, que constó de dos etapas. En la primera etapa, por equipos de trabajo, se identificó las dimensiones que caracterizan a los aspectos de los paisajes bioculturales de comunidades originarias, así como las tres dimensiones más importantes de cada aspecto; en la segunda etapa, de manera grupal, se identificaron las interacciones bosque-agricultura, bosque y agricultura, así como su relación con los objetivos locales de la implementación del modelo de paisajes bioculturales. Concluyendo que la identificación de las interacciones en el manejo forestal y las prácticas agrícolas en comunidades originarias podría facilitar el diseño e implementación de los diferentes objetivos a escala local de dicho modelo

Interacciones en el manejo forestal y las prácticas agrícolas en comunidades originarias del Estado de México, México: el modelo de paisajes bioculturales a escala local: Interactions in forest management and agricultural practices in communities originating from the State of Mexico, Mexico: the biocultural landscape model at a local scale

La implementación del modelo de paisajes bioculturales a escala local en los pueblos originarios de México podría conducir a la resignificación de dichos paisajes bioculturales, ya que permite la integración de prácticas y saberes para su gestión sostenible. El objetivo de este estudio fue identificar las dimensiones que caracterizan a los aspectos de los paisajes bioculturales, así como las interacciones en el manejo forestal y las prácticas agrícolas en comunidades originarias del Estado de México, México, para relacionarlas con los objetivos a escala local del modelo de paisajes bioculturales. Con un enfoque cualitativo, se realizó un taller participativo dirigido a miembros de Organizaciones No Gubernamentales (ONG) y académicos especialistas en el tema, que constó de dos etapas. En la primera etapa, por equipos de trabajo, se identificó las dimensiones que caracterizan a los aspectos de los paisajes bioculturales de comunidades originarias, así como las tres dimensiones más importantes de cada aspecto; en la segunda etapa, de manera grupal, se identificaron las interacciones bosque-agricultura, bosque y agricultura, así como su relación con los objetivos locales de la implementación del modelo de paisajes bioculturales. Concluyendo que la identificación de las interacciones en el manejo forestal y las prácticas agrícolas en comunidades originarias podría facilitar el diseño e implementación de los diferentes objetivos a escala local de dicho modelo. The implementation of the biocultural landscapes model at a local scale in the indigenous peoples of Mexico could lead to the resignification of said biocultural landscapes, since it allows the integration of practices and knowledge for their sustainable management. The objective of this study was to identify the dimensions that characterize the aspects of biocultural landscapes, as well as the interactions in forest management and agricultural practices in communities originating from the State of Mexico, Mexico, to relate them to the local-scale objectives of the biocultural landscape model. With a qualitative approach, a participatory workshop was held aimed at members of Non-Governmental Organizations (NGOs) and academics specializing in the topic, which consisted of two stages. In the first stage, by work teams, the dimensions that characterize the aspects of the biocultural landscapes of native communities were identified, as well as the three most important dimensions of each aspect; In the second stage, in a group manner, the forest-agriculture, forest and agriculture interactions were identified, as well as their relationship with the local objectives of the implementation of the biocultural landscape model. Concluding that the identification of interactions in forest management and agricultural practices in native communities could facilitate the design and implementation of the different objectives at the local scale of said model

Oval Domes: History, Geometry and Mechanics

An oval dome may be defined as a dome whose plan or profile (or both) has an oval form. The word Aoval@ comes from the latin Aovum@, egg. Then, an oval dome has an egg-shaped geometry. The first buildings with oval plans were built without a predetermined form, just trying to close an space in the most economical form. Eventually, the geometry was defined by using arcs of circle with common tangents in the points of change of curvature. Later the oval acquired a more regular form with two axis of symmetry. Therefore, an “oval” may be defined as an egg-shaped form, doubly symmetric, constructed with arcs of circle; an oval needs a minimum of four centres, but it is possible also to build polycentric ovals. The above definition corresponds with the origin and the use of oval forms in building and may be applied without problem until, say, the XVIIIth century. Since then, the teaching of conics in the elementary courses of geometry made the cultivated people to define the oval as an approximation to the ellipse, an “imperfect ellipse”: an oval was, then, a curve formed with arcs of circles which tries to approximate to the ellipse of the same axes. As we shall see, the ellipse has very rarely been used in building. Finally, in modern geometrical textbooks an oval is defined as a smooth closed convex curve, a more general definition which embraces the two previous, but which is of no particular use in the study of the employment of oval forms in building. The present paper contains the following parts: 1) an outline the origin and application of the oval in historical architecture; 2) a discussion of the spatial geometry of oval domes, i. e., the different methods employed to trace them; 3) a brief exposition of the mechanics of oval arches and domes; and 4) a final discussion of the role of Geometry in oval arch and dome design

Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory

The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been used for the past 25 years as a reference source in TeV astronomy, for calibration and verification of new TeV instruments. The High Altitude Water Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe the Crab Nebula at high significance across nearly the full spectrum of energies to which HAWC is sensitive. HAWC is unique for its wide field-of-view, nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's sensitivity improves with the gamma-ray energy. Above $\sim$1 TeV the sensitivity is driven by the best background rejection and angular resolution ever achieved for a wide-field ground array. We present a time-integrated analysis of the Crab using 507 live days of HAWC data from 2014 November to 2016 June. The spectrum of the Crab is fit to a function of the form $\phi(E) = \phi_0 (E/E_{0})^{-\alpha -\beta\cdot{\rm{ln}}(E/E_{0})}$. The data is well-fit with values of $\alpha=2.63\pm0.03$, $\beta=0.15\pm0.03$, and log$_{10}(\phi_0~{\rm{cm}^2}~{\rm{s}}~{\rm{TeV}})=-12.60\pm0.02$ when $E_{0}$ is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the systematic errors in this HAWC measurement is discussed and estimated to be $\pm$50\% in the photon flux between 1 and 37 TeV. Confirmation of the Crab flux serves to establish the HAWC instrument's sensitivity for surveys of the sky. The HAWC survey will exceed sensitivity of current-generation observatories and open a new view of 2/3 of the sky above 10 TeV.Comment: Submitted 2017/01/06 to the Astrophysical Journa