Uso del análisis de conglomerados para la detección de encuadres en el tratamiento periodístico de la Iniciativa Mérida = Use of cluster analysis to detect news frames in the media coverage of the Merida Initiative

Se ha hecho hincapié en la necesidad de la elaboración de estudios para optar por métodos de identificación marco que proporcionan resultados fiables y válidos. En este artículo, se utilizó un análisis de conglomerados para identificar marcos de temas específicos en los artículos de noticias sobre la Iniciativa Mérida, un acuerdo de cooperación internacional que recibió amplia cobertura mediática por sus implicaciones tanto para la política de seguridad de México y la lucha contra el tráfico de drogas. ABSTRACT It has been stressed the need for framing studies to opt for frame identification methods that provide reliable and valid results. In this article, a cluster analysis is used to identify issue-specific frames in the news articles about the Merida Initiative, an international cooperation agreement that received wide media coverage for its implications both for the Mexican security policy and the struggle against drug trafficking

Observation of the Askaryan Effect: Coherent Microwave Cherenkov Emission from Charge Asymmetry in High Energy Particle Cascades

We present the first direct experimental evidence for the charge excess in high energy particle showers predicted nearly 40 years ago by Askaryan. We directed bremsstrahlung photons from picosecond pulses of 28.5 GeV electrons at the SLAC Final Focus Test Beam facility into a 3.5 ton silica sand target, producing electromagnetic showers several meters long. A series of antennas spanning 0.3 to 6 GHz were used to detect strong, sub-nanosecond radio frequency pulses produced whenever a shower was present. The measured electric field strengths are consistent with a completely coherent radiation process. The pulses show 100% linear polarization, consistent with the expectations of Cherenkov radiation. The field strength versus depth closely follows the expected particle number density profile of the cascade, consistent with emission from excess charge distributed along the shower. These measurements therefore provide strong support for experiments designed to detect high energy cosmic rays and neutrinos via coherent radio emission from their cascades.Comment: 10 pages, 4 figures. Submitted to Phys. Rev. Let

Gaussian and Cauchy Functions in the Filled Function Method – Why and What Next: On the Example of Optimizing Road Tolls

Abstract: In many practical problems, we need to find the values of the parameters that optimize the desired objective function. For example, for the toll roads, it is important to set the toll values that lead to the fastest return on investment. There exist many optimization algorithms, the problem is that these algorithms often end up in a local optimum. One of the promising methods to avoid the local optima is the filled function method, in which we, in effect, first optimize a smoothed version of the objective function, and then use the resulting optimum to look for the optimum of the original function. It turns out that empirically, the best smoothing functions to use in this method are the Gaussian and the Cauchy functions. In this paper, we show that from the viewpoint of computational complexity, these two smoothing functions are indeed the simplest. The Gaussian and Cauchy functions are not a panacea: in some cases, they still leave us with a local optimum. In this paper, we use the computational complexity analysis to describe the next-simplest smoothing functions which are worth trying in such situations. Keywords: optimization; toll roads; filled function method; Gaussian and Cauchy smoothin

La orientación política del periódico y su influencia en la presencia de encuadres y asuntos dentro de las noticias

Resumen. Las investigaciones sobre el papel de la orientación política de los periódicos en los contenidos son escasas. En este artículo se buscó explorar la significatividad de esta variable mediante la comparación del tratamiento y prominencia del asunto de la Iniciativa Mérida en tres periódicos mexicanos de diferente orientación política. Para esto, se identificaron los encuadres en las notas mediante un análisis de conglomerados jerárquico y se compararon la prominencia del asunto, la presencia de elementos de encuadres y la presencia de encuadres. Se hallaron diferencias significativas en los temas, las atribuciones causales, las evaluaciones morales y los encuadres que pueden atribuirse al papel de la orientación política. Asimismo, la cantidad de notas sobre el asunto y las menciones de actores en los periódicos de diferente orientación política fueron similares. Palabras clave: Framing; periodismo; línea editorial; orientación política. Abstract. The empirical research in which the role of the political orientation of the newspapers is systematically examined is scarce. The objective of this article is to explore the significance of this variable by comparing the framing and salience of the issue of the Merida Initiative in three Mexican newspapers with different political orientation. To this end, we inductively identified the frames in the reports using a cluster analysis. After that, we compared the salience of the issue, the presence of frame elements and the presence of frames in the three newspapers. Significant differences were found in topics, issue-specific frames and value judgments, all of these attributable to the role of political orientation. Nevertheless, there were similarities in the number of reports devoted to the issue and in the actors mentioned. Keywords: Framing; Merida Initiative; newspapers; political orientatio

Neutrino Induced Upward Going Muons from a Gamma Ray Burst in a Neutrino Telescope of Km^2 Area

The number of neutrino induced upward going muons from a single Gamma Ray Burst (GRB) expected to be detected by the proposed kilometer scale IceCube detector at the South Pole location has been calculated. The effects of the Lorentz factor, total energy of the GRB emitted in neutrinos and its distance from the observer (red shift) on the number of neutrino events from the GRB have been examined. The present investigation reveals that there is possibility of exploring the early Universe with the proposed kilometer scale IceCube neutrino telescope.Comment: 18pages, 5 figures. Physical Review D in pres

Effect of a Diet Supplemented with α-Tocopherol and β-Carotene on ATP and Antioxidant Levels after Hepatic Ischemia-Reperfusion

Ischemia-reperfusion injury associated with liver transplantation remains a serious complication in clinical practice. In the present study the effect of intake of α-tocopherol or β-carotene to limit liver injury by oxidative stress in ischemia and reperfusion was explored. Wistar rats were fed with diets enriched with α-tocopherol (20 mg/day) or β-carotene (3 mg/day) for 21 days. After 21 days, their livers were subjected to 15 and 30 min of ischemia and afterwards were reperfused for 60 min. The recovery of levels of ATP during reperfusion was better in the group of rats whose diets were supplemented with α-tocopherol or β-carotene than in the group control. The supplementation of the diet induced changes in the profile of enzymatic antioxidants. The supplementation with α-tocopherol and β-carotene resulted in a decreased of superoxide dismutase during the ischemia and a recovery was observed after reperfusion. Not changes were observed for the enzymes catalase and glutathione peroxidase and glutathione but their values were higher to those of the group control. In conclusion, the supplementation with α-tocopherol and β-carotene improve the antioxidant and energetic state of liver after ischemia and reperfusion injury

Radio Detection of High Energy Particles: Coherence Versus Multiple Scales

Radio Cherenkov emission underlines detection of high energy particles via a signal growing like the particle-energy-squared. Cosmic ray-induced electromagnetic showers are a primary application. While many studies have treated the phenomenon approximately, none have attempted to incorporate all the physical scales involved in problems with time- or spatially- evolving charges. We find it is possible to decompose the calculated fields into the product of a form factor, characterizing a moving charge distribution, multiplying a general integral which depends on the charge evolution. In circumstances of interest for cosmic ray physics, the resulting expressions can be evaluated explicitely in terms of a few parameters obtainable from shower codes. The classic issues of Frauhofer and Fresnel zones play a crucial role in the coherence.Comment: 25 pages, 10 figure

Energy and Flux Measurements of Ultra-High Energy Cosmic Rays Observed During the First ANITA Flight

The first flight of the Antarctic Impulsive Transient Antenna (ANITA) experiment recorded 16 radio signals that were emitted by cosmic-ray induced air showers. For 14 of these events, this radiation was reflected from the ice. The dominant contribution to the radiation from the deflection of positrons and electrons in the geomagnetic field, which is beamed in the direction of motion of the air shower. This radiation is reflected from the ice and subsequently detected by the ANITA experiment at a flight altitude of 36km. In this paper, we estimate the energy of the 14 individual events and find that the mean energy of the cosmic-ray sample is 2.9 EeV. By simulating the ANITA flight, we calculate its exposure for ultra-high energy cosmic rays. We estimate for the first time the cosmic-ray flux derived only from radio observations. In addition, we find that the Monte Carlo simulation of the ANITA data set is in agreement with the total number of observed events and with the properties of those events.Comment: Added more explanation of the experimental setup and textual improvement

Collective behavior in nuclear interactions and shower development

The mechanism of hadronic interactions at very high energies is still unclear. Available accelerator data constrain weakly the forward rapidity region which determines the development of atmospheric showers. This ignorance is one of the main sources of uncertainty in the determination of the energy and composition of the primary in hadron-induced atmospheric showers. In this paper we examine the effect on the shower development of two kinds of collective effects in high-energy hadronic interactions which modify the production of secondary particles. The first mechanism, modeled as string fusion, affects strongly the central rapidity region but only slightly the forward region and is shown to have very little effect on the shower development. The second mechanism implies a very strong stopping; it affects modestly the profile of shower maximum but broadens considerably the number distribution of muons at ground. For the latter mechanism, the development of air showers is faster mimicking a heavier projectile. On the other hand, the number of muons at ground is lowered, resembling a shower generated by a lighter primary.Comment: 17 pages, 10 figure