904 resultados para Black bear.
Black yeasts from the slope sediments of Bay of Bengal: phylogenetic and functional characterization
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Occurrence of black yeasts in the slope sediments of Bay of Bengal was investigated during FORV Sagar Sampada cruises 236 and 245. The black yeast population was found to be very scanty in the area and the isolates could be obtained from 200m to 1000m depth regions in the slope sediments. The isolates were identified as Hortaea werneckii by Internal Transcribed Spacer (ITS) sequencing. The biodegradation potential of these strains was found to be very high with all the strains exhibiting protease, lipase and amylase production. The optimum growth conditions were pH 8, salinity 30 ppt and temperature 30oC. The pigment melanin, in these organisms was identified to be of dihydroxynaphthalene type by NMR. The melanin was found to exhibit inhibitory activity against different human and fish pathogens. Melanin degrading enzyme could also be extracted from these organisms
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Fine particles of barium ferrite (BaFe12O19) were synthesized by the conventional ceramic technique. These materials were then characterized by the X-ray diffraction method and incorporated in the natural rubber matrix according to a specific receipe for various loadings of ferrite. The rubber ferrite composites (RFC) thus obtained have several applications, and have the advantage of molding into complex shapes. For applications such as microwave absorbers, these composites should have an appropriate dielectric strength with the required mechanical and magnetic properties. The N330 (HAF) carbon black has been added to these RFCs for various loadings to modify the dielectric and mechanical properties. In this article we report the effect of carbon black on the mechanical and dielectric properties of these RFCs. Both the mechanical and dielectric properties can be enhanced by the addition of an appropriate amount of carbon black
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Fine particles of barium ferrite (BaFe12O19) belonging to the M-type hexagonal ferrites were prepared by the conventional ceramic techniques. They were incorporated into a nitrile rubber matrix according to a specific recipe for various loadings to produce rubber ferrite composites (RFC). The percolation threshold is not reached for a maximum loading of 130 phr (parts per hundred rubber). Here in this paper, the magnetic properties and processability of the nitrile rubber based RFCs containing barium ferrite (BaF) and HAF carbon black is reported. The magnetic properties of the ceramic ferrite and these rubber ferrite composites were evaluated and it was found that the coercivity values of RFCs were less than that of the ceramic BaF, but remained constant with the loading of both the ferrite filler and carbon black. However, other properties like saturation magnetization and magnetic remanence increased with the loading of ferrite filler.
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Flexile single layer electromagnetic wave absorbers were designed by incorporating appropriate amounts of carbon black in a nitrile butadiene rubber matrix along with an optimized amount of magnetic counterpart, namely, barium hexaferrite for applications in S, C, and X-bands. Effective dielectric permittivity and magnetic permeability were measured using cavity perturbation method in the frequency range of 2–12 GHz. The microwave absorbing characteristics of the composites were studied in the S, C, and X-bands employing a model in which an electromagnetic wave is incident normally on a metal terminated single layer. Reflection loss exceeding 20 dB is obtained for all the samples in a wide frequency range of 2–12 GHz when an appropriate absorber thickness between 5 and 9mm is chosen. The impact of carbon black is clearly observed in the optimized composites on the mechanical strength, thickness, band width of absorption, dielectric properties,
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One of the interesting consequences of Einstein's General Theory of Relativity is the black hole solutions. Until the observation made by Hawking in 1970s, it was believed that black holes are perfectly black. The General Theory of Relativity says that black holes are objects which absorb both matter and radiation crossing the event horizon. The event horizon is a surface through which even light is not able to escape. It acts as a one sided membrane that allows the passage of particles only in one direction i.e. towards the center of black holes. All the particles that are absorbed by black hole increases the mass of the black hole and thus the size of event horizon also increases. Hawking showed in 1970s that when applying quantum mechanical laws to black holes they are not perfectly black but they can emit radiation. Thus the black hole can have temperature known as Hawking temperature. In the thesis we have studied some aspects of black holes in f(R) theory of gravity and Einstein's General Theory of Relativity. The scattering of scalar field in this background space time studied in the first chapter shows that the extended black hole will scatter scalar waves and have a scattering cross section and applying tunneling mechanism we have obtained the Hawking temperature of this black hole. In the following chapter we have investigated the quasinormal properties of the extended black hole. We have studied the electromagnetic and scalar perturbations in this space-time and find that the black hole frequencies are complex and show exponential damping indicating the black hole is stable against the perturbations. In the present study we show that not only the black holes exist in modified gravities but also they have similar properties of black hole space times in General Theory of Relativity. 2 + 1 black holes or three dimensional black holes are simplified examples of more complicated four dimensional black holes. Thus these models of black holes are known as toy models of black holes in four dimensional black holes in General theory of Relativity. We have studied some properties of these types of black holes in Einstein model (General Theory of Relativity). A three dimensional black hole known as MSW is taken for our study. The thermodynamics and spectroscopy of MSW black hole are studied and obtained the area spectrum which is equispaced and different thermo dynamical properties are studied. The Dirac perturbation of this three dimensional black hole is studied and the resulting quasinormal spectrum of this three dimensional black hole is obtained. The different quasinormal frequencies are tabulated in tables and these values show an exponential damping of oscillations indicating the black hole is stable against the mass less Dirac perturbation. In General Theory of Relativity almost all solutions contain singularities. The cosmological solution and different black hole solutions of Einstein's field equation contain singularities. The regular black hole solutions are those which are solutions of Einstein's equation and have no singularity at the origin. These solutions possess event horizon but have no central singularity. Such a solution was first put forward by Bardeen. Hayward proposed a similar regular black hole solution. We have studied the thermodynamics and spectroscopy of Hay-ward regular black holes. We have also obtained the different thermodynamic properties and the area spectrum. The area spectrum is a function of the horizon radius. The entropy-heat capacity curve has a discontinuity at some value of entropy showing a phase transition.
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How we get from transistors through to logic gates to ALUs and memory to the stored program and the fetch execute cycle through to machine code and high level languages. Inspired by Tanenbaum's approach in "Structured Computer Organozation"
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La teoría de restricciones, más conocida como TOC, es una herramienta que permite el diagnóstico empresarial, identificando causas y efectos que afectan a la misma; en el desarrollo de esta tesis se realiza un diagnóstico TOC de la empresa BLACK PENGUIN S.A.S en el cual se considera la parte financiera donde se calculan y examinan las cuentas en términos TOC con medidores que ayudan a determinar las falencias en que incurre la empresa en su proceso productivo y de gestión administrativa, posteriormente se realiza una identificación de los efectos indeseables( EIDEs ) y las nubes de problema encontradas en la empresa, para de esta forma elaborar el árbol de realidad actual, y conocer el estado del arte de la organización. El desarrollo de diferentes análisis estratégicos como la cadena de valor y el análisis matricial servirán como punto de referencia para el desarrollo del Mejoramiento En Ambiente T.O.C.
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El osito no puede dormir pues tiene miedo a la oscuridad aunque el papá Oso le ha colocado un gran farol encendido sobre la cama para que no se asuste. El Gran Oso encuentra una ingeniosa manera de tranquilizarlo.
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Historia de un niño y un oso que van juntos a todas partes, hasta que un día al niño se le olvida el oso, que se había quedado sentado en una silla del parque. Las peripecias nocturnas que le ocurren con una lechuza y un músico, hasta que el amigo se acuerda del oso y va a buscarle.
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El niño, el perro y el oso se van de excursión. El niño prepara en paquetes la comida para el almuerzo y los guarda en una caja. El oso la vigila pero el perro, como es costumbre, origina todos los problemas. Esta historia es idónea para primeros lectores.
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Un padre y sus cuatro hijos se lanzan a la caza del oso, al ritmo de un tradicional canto de campamento. Resbalan por una ladera cubierta de hierba, cruzan un río, atraviesan lodos y barro y llegan a un bosque, pasan una ventisca y encuentran, al final, al oso pardo que les persigue hasta su casa. Es una lectura idónea para niños de cuatro a nueve años.
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El osito despierta por la mañana y descubre que ha perdido sus pantalones. Vemos los distintos e ingeniosos usos que pueden tener un par de pantalones para algunos de los juguetes del osito. El camello, el marinero, el perro y el conejo los han utilizado para diversos fines sin saber lo que realmente son.
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El formato repetitivo está diseñado para ayudar a los niños a aprender los nombres de los colores y de los animales. Las ilustraciones collage a doble página, cuentan con un oso pardo, un pájaro rojo, un pato amarillo, un caballo azul, una rana verde, un gato morado, un perro blanco y una oveja negra, que invitan a descubrir la criatura que mostrarán a continuación. Imágenes identificables y repetición rítmica de preguntas y respuesta del texto es el patrón se repite una y otra vez, hasta que el pre-lector puede predecir fácilmente la siguiente rima. Una cosa que los lectores tal vez no pueden predecir, sin embargo, es el tipo de personaje que hará su aparición en el desenlace. Para lectura interactiva en voz alta entre el profesor y los alumnos y para lectura compartida.
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Para que los niños comiencen a comprender la importancia de las personas, aunque tengan características especiales. Un osito de peluche no puede entender por qué nadie va a comprarlo, hasta que descubre que es defectuoso, tiene la boca al revés. Termina en el escaparate de una tienda de segunda mano y el sol convierte su piel marrón en mandarina, pero las cosas no son siempre tan sombrías ya que un cliente ofrece comprarlo, y de repente el propietario declara que no está a la venta, ya que él es la única familia que tiene. La melancolía del osito se desvanece al instante.
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Cuento de fantasía y amistad. Anthony desea poder ir a la luna, pero su padre no puede construir una nave espacial. Su amigo imaginario Oso Pizarra, por supuesto, sabe lo que hacer, por lo que tanto él como Anthony diseñan la nave perfecta y la llenan con comida, agua y otros artículos de primera necesidad. Preocupado por si podrían encontrar monstruos en la luna, Anthony decide permanecer seguro y caliente en casa, con su peluche. Oso Pizarra regresa de las estrellas con un recuerdo para su amigo.