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Search Results: 1 - 10 of 13193 matches for " Luz Adriana Nicasio-Collazo "
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Hysteresis in Pressure-Driven DNA Denaturation
Enrique Hernández-Lemus, Luz Adriana Nicasio-Collazo, Ramón Casta?eda-Priego
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033789
Abstract: In the past, a great deal of attention has been drawn to thermal driven denaturation processes. In recent years, however, the discovery of stress-induced denaturation, observed at the one-molecule level, has revealed new insights into the complex phenomena involved in the thermo-mechanics of DNA function. Understanding the effect of local pressure variations in DNA stability is thus an appealing topic. Such processes as cellular stress, dehydration, and changes in the ionic strength of the medium could explain local pressure changes that will affect the molecular mechanics of DNA and hence its stability. In this work, a theory that accounts for hysteresis in pressure-driven DNA denaturation is proposed. We here combine an irreversible thermodynamic approach with an equation of state based on the Poisson-Boltzmann cell model. The latter one provides a good description of the osmotic pressure over a wide range of DNA concentrations. The resulting theoretical framework predicts, in general, the process of denaturation and, in particular, hysteresis curves for a DNA sequence in terms of system parameters such as salt concentration, density of DNA molecules and temperature in addition to structural and configurational states of DNA. Furthermore, this formalism can be naturally extended to more complex situations, for example, in cases where the host medium is made up of asymmetric salts or in the description of the (helical-like) charge distribution along the DNA molecule. Moreover, since this study incorporates the effect of pressure through a thermodynamic analysis, much of what is known from temperature-driven experiments will shed light on the pressure-induced melting issue.
RACISMO INSTITUCIONAL, VIOLENCIA Y POLíTICAS CULTURALES: LEGADOS COLONIALES Y POLíTICAS DE LA DIFERENCIA EN COLOMBIA
Maya Restrepo,Luz Adriana;
Historia Crítica , 2009,
Abstract: this article is part of a line of thought that i proposed in another article "memories in confict and peace in colombia: discrimination towards blackness and black people", in which i planted the seeds for a study about racism and discrimination towards the descendents of african people in colombia not only as an everyday practice but especially as a long-standing problem tied to the institutional culture of the state. from an historical perspective, this institutional culture has its roots in the colonial legacy of imperial administration and its transformations during the republican period. i suggest that the politics of imperial and colonial difference are still felt in the contemporary colombian state. i also raise various questions about the commitment of intellectuals, historians, and geographers with regard to public policies.
Generación y flujo del ahorro y la inversión: análisis de la coyuntura internacional
Luz Adriana Flórez
Perfil de Coyuntura Económica , 2005,
Abstract: El comportamiento del ahorro y la inver- sión mundial ha cambiado de manera im- portante en los últimos cinco a os. Los ca- pitales excedentes de las economías emer- gentes se han dirigido hacia las economías desarroladas. Este comportamiento está explicado en parte por un choque positivo de productividad en los países emergentes y uno negativo en los desarrolados, ade- más de las diferentes políticas económicas en ambas regiones. En este sentido, el ex- ceso de ahorro de las economías asiáticas, especialmente de China y los países exportadores de petróleo, ha estado finan- ciando una gran parte del consumo de la economía norteamericana. Adicionalmente, este ahorro ha impulsado una fuerte caída en las tasas de interés de largo plazo y un crecimiento en los precios de la vivienda de las economías desarroladas. Los facto- res que han movido estas decisiones de ahorro e inversión mundial no cambiarán fácilmente; de esta manera es probable que los desequilibrios generados por este cam- bio permanezcan por un buen tiempo.
áfrica: legados espirituales en la nueva granada, siglo XVII.
Luz Adriana Maya Restrepo
Historia Crítica , 1996,
Abstract:
Botánica y Medicina africanas en la Nueva Granada, Siglo XVII.
Luz Adriana Maya Restrepo.
Historia Crítica , 2000,
Abstract: La relación que los bozales (africanos que llegaban directamente de Africa que no se expresaban en lengua castellana ni conocían la fe católica) y sus hijos nacidos en la Nueva Granada mantuvieron con los vegetales y los animales, en particular las aves, es otro de los legados ancestrales que la nación colombiana le debe a Africa. Los africanos le transmitieron a sus descendientes saberes y técnicas sobre el mundo vegetal y animal. Estos conocimientos, que fueron utilizados para curar los males del cuerpo y los del alma, se caracterizaban por un componente experimental cuyo éxito dependía también de la interacción con los espíritus. De ahí que el Tribunal de la Inquisición de Cartagena hubiera juzgado a los africanos y a sus hijos en calidad de "brujos(as)", "hechiceros(as)" y "curanderos(as)".
En memoria de Ignacio “Nacho” Abello.
Luz Adriana Maya Restrepo.
Historia Crítica , 2010,
Abstract:
THE ETERNAL RETURN TERRITORY
Luz Adriana Henao Quintero
Luna Azul , 2006,
Abstract: The new dynamics, which have arisen in the context of globalization, are transforming cultures and their relationships, productive and commercial activities, territorial vision and its management. This situation is due to the incorporation of strategies and activities which are more immaterial and impersonal by the day. It is not possible to deny that global effects and their virtual technological platforms are crossing urban and rural environments indistinctively, using a totalizing and uniting effect in which communications are the instrument and the means to integration or, perhaps, disintegration. This new global cultural perspective with the resulting influence of the media will change individual perceptions and will modify social relationships in communities and territories. Rural territory doesn’t escape this new global dimension, alternative functioning structures will penetrate every day activities, and country culture, its activities and times, will undoubtedly be transformed. The traditional farmer and his space—time relationship which historically has meant the “Eternal Return” time will possibly end or, at least, suffer notable transformations. Time in the rural environment, usually cyclic, in which day by day beginning to end are united, will be altered by the penetration and action of this new paradigm. The only thing left is just to consider the opportunities and challenges that emerge from this new scenario, as well as obtaining all of their potential in order to find their sustainability
Hyperbolic sets that are not contained in a locally maximal one
Adriana da Luz
Mathematics , 2013,
Abstract: In this paper we study two properties related to the structure of hyperbolic sets. First we construct new examples answering in the negative the following question posed by Katok and Hasselblatt. Let $\Lambda$ be a hyperbolic set, and let $V$ be an open neighborhood of $\Lambda$. Does there exist a locally maximal hyperbolic set $\widetilde{\Lambda}$ such that $\Lambda \subset \widetilde{\Lambda} \subset V $? We show that such examples are present in linear anosov diffeomorophisms of $\mathbb{T}^3$, and are therefore robust. Also we construct new examples of sets that are not contained in any locally maximal hyperbolic set. The examples known until now were constructed by Crovisier and by Fisher, and these were either in dimension bigger than 4 or they were not transitive. We give a transitive and robust example in $\mathbb{T}^3$. And show that such examples cannot be build in dimension 2.
EFECTO DEL SISTEMA DE LABOREO EN LAS PéRDIDAS DE SUELO POR EROSIóN EN LA ROTACIóN TRIGO-AVENA Y PRADERAS EN LA PRECORDILLERA ANDINA DE LA REGIóN CENTRO SUR
Rodríguez S.,Nicasio; Ruz J.,Emilio; Valenzuela P.,Adriana; Belmar N.,Ciro;
Agricultura Técnica , 2000, DOI: 10.4067/S0365-28072000000300006
Abstract: a study for evaluating soil erosion as a result of four different tillage systems was carried out from 1994 to 1996 on a volcanic soil (dystrandepts) at san pedro, ?uble province, in the foothills of the chilean andes (lat. 37° 47′ s ; long. 72° 01′0). four soil treatments were evaluated using a completely randomized block design with three repetitions: conventional tillage (lc), vertical plowing (lv), direct drilling (sd) and permanent pasture (p). surface drainage and erosion were measured in 11 m plots. the results obtained in each of the seasons indicate the highest soil losses are associated with the use of lc and decrease 4 to 5 times with lv and sd: (lc 19.3 t ha-1; lv 5.5 t ha-1; sd 3.0 t ha-1 and p 0.64 t ha-1). the largest losses occurred during winter, in june, july and august, in which months the soil is saturated with water. after august, vegetative cover provided by wheat reduced the beating action of the rain, increased the infiltration and reduced the surface runoff. associated with the soil erosion, there was a loss of organic matter that for lc was of 2381 kg ha-1 yr-1, which is six times higher than for the other treatments. the total nitrogen was significantly reduced by lc, 121 kg ha-1 yr-1, whereas slight losses occurred when employing soil conservation methods.
EFECTO DEL SISTEMA DE LABOREO EN LAS PéRDIDAS DE SUELO POR EROSIóN EN LA ROTACIóN TRIGO-AVENA Y PRADERAS EN LA PRECORDILLERA ANDINA DE LA REGIóN CENTRO SUR Effect of tillage on soil erosion losses with a wheat-oat rotation and pasturing in the Andean foothills of the south-central region of Chile
Nicasio Rodríguez S.,Emilio Ruz J.,Adriana Valenzuela P.,Ciro Belmar N.
Agricultura Técnica , 2000,
Abstract: Se realizó un estudio durante tres temporadas agrícolas (1994 a 1996) en un suelo de origen volcánico reciente (Dystrandeps) de la precordillera andina en la localidad de San Pedro (Lat. 37° 47’S; Long. 72° 01’0) provincia de uble, área centro sur de Chile, con el objetivo de cuantificar las pérdidas de suelo asociadas al empleo de diferentes tipos de labranza del suelo. Se realizaron cuatro tratamientos de manejo del suelo : labranza convencional (LC), labranza vertical (LV), siembra directa (SD) y pradera natural (P), con tres repeticiones y en un arreglo de bloques completos al azar. Los resultados obtenidos en cada una de las temporadas indican que las mayores pérdidas anuales de suelo están asociadas al empleo de LC con un valor de 20 t ha-1a o-1 y disminuyen 4 a 5 veces con LV y SD. Las pérdidas de suelo se asocian al escurrimiento del agua de lluvia en las diferentes condiciones del suelo como consecuencia de los sistemas de labranza. El mayor escurrimiento corresponde a los meses de junio, julio y agosto en los cuales el suelo está saturado. Después de agosto la cubierta vegetal proporcionada por el trigo disminuye la energía de las gotas de lluvia aumentando la infiltración y disminuyendo el escurrimiento de sedimentos por la ladera. Asociado al escurrimiento de sedimentos existe una pérdida de materia orgánica que en LC es de 2.381 kg ha-1 a o-1, seis veces superior a los demás tratamientos. El nitrógeno total disminuye en 154,6 kg-1 ha-1 a o-1 en LC, obteniéndose escasas pérdidas con el empleo de métodos de conservación . A study for evaluating soil erosion as a result of four different tillage systems was carried out from 1994 to 1996 on a volcanic soil (Dystrandepts) at San Pedro, uble province, in the foothills of the Chilean Andes (Lat. 37° 47′ S ; Long. 72° 01′0). Four soil treatments were evaluated using a completely randomized block design with three repetitions: conventional tillage (LC), vertical plowing (LV), direct drilling (SD) and permanent pasture (P). Surface drainage and erosion were measured in 11 m plots. The results obtained in each of the seasons indicate the highest soil losses are associated with the use of LC and decrease 4 to 5 times with LV and SD: (LC 19.3 t ha-1; LV 5.5 t ha-1; SD 3.0 t ha-1 and P 0.64 t ha-1).The largest losses occurred during winter, in June, July and August, in which months the soil is saturated with water. After August, vegetative cover provided by wheat reduced the beating action of the rain, increased the infiltration and reduced the surface runoff. Associated with the soil erosion, there wa
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