Arrendajo – Garrulus glandarius (Linnaeus, 1758)

Aves - Orden Passeriformes - Familia Corvidae en la Enciclopedia Virtual de Vertebrados Españoles, http://www.vertebradosibericos.org/. Versiones anteriores: 3-04-2006; 18-01-2007; 15-02-2008; 24-02-2010A comprehensive review of the natural history of the jay Garrulus glandarius in Spain.Peer reviewe

Diffraction by random Ronchi gratings

In this work, we obtain analytical expressions for the near-and far-field diffraction of random Ronchi diffraction gratings where the slits of the grating are randomly displaced around their periodical positions. We theoretically show that the effect of randomness in the position of the slits of the grating produces a decrease of the contrast and even disappearance of the self-images for high randomness level at the near field. On the other hand, it cancels high-order harmonics in far field, resulting in only a few central diffraction orders. Numerical simulations by means of the Rayleigh–Sommerfeld diffraction formula are performed in order to corroborate the analytical results. These results are of interest for industrial and technological applications where manufacture errors need to be considered

Self-imaging of gratings with rough strips

We analyze the self-imaging process produced by a transmission grating whose strips present two different roughness levels. This kind of grating periodically modulates the transmitted light owing only to the different microtopographic properties of the strips. In spite of the fact that the grating is not purely periodic, it produces a kind of self-image at Talbot distances. These self-images gradually appear as light propagates, but they are not present just after the grating, as occurs in amplitude or phase gratings. There exists a distance from the grating, which depends on the stochastic properties of roughness, from which the contrast of the self-images becomes stable. Important cases are analyzed in detail, such as low- and high-roughness limits. We assume for the calculations that the grating can be used in a mobile system. Simulations using the Rayleigh–Sommerfeld regime have been performed, which confirm the validity of the theoretical approach proposed in this wor

Far field diffraction of gratings with two roughness levels

We investigate the far field diffraction process produced by diffraction gratings with two roughness levels, such as steel tape gratings, which are used in environments where diffraction gratings made of glass are not possible. We obtain the analytical formulation describing the formation of diffraction orders in terms of the roughness parameters. Since roughness is stochastic, we use the mutual coherence function to propagate the field to the Fraunhofer regime. We conclude that diffraction orders exists when at least one correlation length of both roughness is larger than the period of the grating and the standard deviation on heights is around or larger than the illumination wavelength. Finally, we corroborate the analytical results with numerical simulations based on the fast Fourier transform, showing a high agreement

Collimation technique and testing applied to finite size polychromatic sources

Highly collimated beams are required in numerous applications and techniques. Different methods have been proposed for collimating monochromatic point light sources during the recent years. In this work, we analyze how a finite size and polychromatic light source can be collimated using only one diffraction grating and a CMOS camera placed after the source and the collimating lens. For this, we determine the period of the fringes diffracted by the grating and compare it with the period of the grating. Analytical equations are obtained to predict the amplitude of the fringes and their period. Since self-images disappear for finite size polychromatic sources at long distances from the grating, the period has to be measured close to the grating. In addition, we give an analytical equation to determine the error in the positioning of the source in terms of the source size and the setup parameters. Finally, we experimentally corroborate the obtained analytical formalism using a white LED of size s = 0.6 mm collimated by a lens with focal length f = 25 mm, and a Ronchi binary grating of period d = 250 µm. In this case, we achieve an experimental error in the positioning of the source with respect to the focal plane of the lens of dzexp = 92 µm

La globalización en la gestión de las pequeñas y medianas empresas (pymes) de confecciones en San Juan de Lurigancho, periodo 2011 – 2012.

El presente trabajo tiene por finalidad verificar la incidencia de la globalización en la gestión de las pequeñas y medianas empresas del sector confecciones del distrito de San Juan de Lurigancho. En la globalización se consideran aspectos como la comunicación, la competitividad, tecnología, la apertura de mercados, el comercio internacional, la inversión extranjera. En la gestión empresarial se estudian aspectos como el proceso administrativo, eficiencia, recursos humanos, recursos económicos, infraestructura. Para lo cual se tratará de investigar cuáles son sus debilidades y fortalezas frente a la globalización. Se analiza además experiencias nacionales e internacionales y como han evolucionado en el tiempo a fin de que sirva para comparar y hacer los reajustes necesarios para lograr un mayor desarrollo en las empresas del distrito de San Juan de Lurigancho. Es conveniente mencionar la situación de crisis mundial y las causas externas afectan tanto la demanda como los precios de los productos, por lo que el gobierno en algún momento debe apoyar y dar protección a las empresas de confecciones que muchas veces son muy volátiles. Palabras claves: Globalización, gestión, competitividad, tecnología, nuevos mercados, eficiencia.--- The present work has by finality study the incidence of the globalization in the negotiation of the small and long billiard me Enterprise of the district San Juan de Lurigancho. In the globalization to consider aspects, as the communication, the competitive, technology and opening the marketing, international trade, forcing investment. In the gestion enterprise is study aspects as the process administrative, efficiency, humans resources, economics, infrastructure. For would treat of investigate what is his debility and strong in front of globalization. Besides analysis national experiences and internationals and how is evolution in the time with the finality the comparation y make read just necessary for obtains a great development in this district belong to Lima. Would mentioned the crisis situation of level world and the for causes affect the demand as the prices of the products. By the government in some humant must support give protection and the enterprise of the any hand works that many time are volatiles.Tesi

Diffraction by gratings with random fill factor

In this work, we analyze the diffraction produced by Ronchi gratings where the fill factor is not constant, but presents random fluctuations around its nominal value. This effect can be produced while developing the grating with etchers since the process can be slightly unpredictable. We obtain the theoretical formalism to describe the intensity produced by the grating at near and far field, showing that smoothing of the self-images is produced at the near field and, consequently, cancellation of higher diffraction orders is obtained at the far field. In addition, different nominal fill factors produce different diffraction behaviors in terms of the randomness. We corroborate the analytical formalism using a direct integration method based on the Rayleigh-Sommerfeld formula and conclude that the numerical results are in high agreement with the theoretical predictions

La industria minera y el medio ambiente

In this period of its history , humanity building on the achievements of scientific and technical progress has played and mastered the use of the Ocean and the Cosmos. At the time it was evident that some types of human activity impact negatively on the environment and their consequences will be disastrous in the future. Every time we realize that humanity can not and should not thoughtlessly use its enormous power , not breaking into nature on a limited scale and radically remake without complying with the possible negative consequences of economic activity. The more transformations occur in natural resources, can not be neglected the effects of change occurring in the biosphere as a result of productive activity . Depth studies of the ecological situation indicate that continue to influence unilaterally and spontaneously considerably in the same degree , humanity could make our civilization in a purely technicist creature who not only transformed deserts into oasis but also what that was what become desert oasis and threatens to kill all life on earth. The problem of environmental pollution and other negative impacts of the economic activity of man on earth, reaches the size of the spontaneous influx of men over nature, in cooperation with it in a conscious , oriented and planned. Many ecologists believe that there is widespread losses throughout the world, are the main ecological and social problem. Therefore, man is the main pollutant of the environment through the processes that are related to their daily lives, their productive activity and comfort. In all these processes, solid, liquid and gaseous wastes that eventually will contaminate nature are generated . In the case of Peru is a purely mining country , from colonial times , where and minerals, especially precious metals were mined , it has been polluted in the easiest places to drain the tailings , such as rivers , a current special case is given in the Central region , where the Centromin Peru Mining Company , for many years it has been polluting the Mantaro river , this river is quite plentiful and supplies water to the region for irrigation and other activities, however due to the amount of chemicals that are thrown has polluted the watershed, it can be appreciated on several tens of kilometers, by its reddish color, the same as it is not used by people just for the danger of seriously affect the plants and animals, even humans.En este período de su historia, la humanidad aprovechando los logros del progreso científico técnico ha tocado y asimilado el uso del Océano y del Cosmos. A su vez ha sido evidente, que algunos tipos de actividad humana inciden de manera negativa en el medio ambiente y que sus consecuencias serán muy nefastas en el futuro. Cada vez nos damos cuenta que la humanidad no puede ni debe usar de manera irreflexiva su enorme poder, tampoco irrumpir en la naturaleza a una escala limitada y rehacerla radicalmente sin atenerse a las posible consecuencias negativas de su actividad económica. Cuanto más transformaciones se produzcan en los recursos naturales, no pueden dejarse de lado los efectos, del cambio que se produce en la biosfera a raíz de la actividad productiva. Estudios profundos de la situación ecológica indican que, de seguir influyendo de manera unilateral y espontánea en un grado considerablemente en la misma, la humanidad podría convertir nuestra civilización, en una criatura puramente tecnicista, que no sólo transforma los desiertos en oasis sino que además lo que fuera oasis lo convierta en desierto y amenace con matar todo lo vivo en la tierra. El problema de la polución del medio ambiente y de otros impactos negativos de la actividad económica del hombre en la tierra, alcanza la dimensión del influjo espontáneo de los hombres sobre la naturaleza, en la cooperación con ella de un modo consciente, orientado y planificado. Muchos ecólogos consideran que las pérdidas ampliamente difundidas hay por todo el mundo, constituyen el principal problema ecológico y social. Por lo tanto, el hombre es el principal agente contaminador del medio ambiente a través de los procesos que están ligados a su vida cotidiana, su actividad productiva y comodidad. En todos estos procesos se generan desechos sólidos, líquidos y gaseoso que finalmente van a contaminar la naturaleza. En el caso del Perú que es un país puramente minero, desde la época de la Colonia, donde ya se extraían minerales, especialmente los metales preciosos; se ha venido contaminando en los lugares más fáciles de desaguar los relaves, como son los ríos; una caso especial de actualidad esta dado en la región central, donde se encuentra la Empresa Minera Centromin Perú, desde hace muchos años viene contaminando el río Mantaro, este río es bastante caudaloso y abastece de agua a toda la región para el riego y otras actividades, sin embargo debido a la cantidad de elementos químicos que son arrojados ha contaminado la cuenca, ello se puede apreciar en varias decenas de kilómetros, por su color rojizo, la misma que no es utilizada por los pobladores justamente por el peligro de afectar seriamente a las plantas y animales, incluso para el hombre

Single-focus binary Fresnel zone plate

In this work, we propose and analyze a novel kind of binary Fresnel zone plate with single focus. It consists of a Fresnel zone plate whose zones have rough edges. We give analytical results for the intensity along the optical axis and demonstrate that lateral roughness of the zones produces the disappearance of secondary foci as a blurring of the edges. Besides, we corroborate its behavior by numerical simulations and experiments. This kind of Fresnel zone plate can be useful in a wide range of photonic applications, even for focusing with soft and hard X-rays or extreme ultraviolet radiation