Optimal length and signal amplification in weakly activated signal transduction cascades

Weakly activated signaling cascades can be modeled as linear systems. The input-to-output transfer function and the internal gain of a linear system, provide natural measures for the propagation of the input signal down the cascade and for the characterization of the final outcome. The most efficient design of a cascade for generating sharp signals, is obtained by choosing all the off rates equal, and a ``universal'' finite optimal length.Comment: 27 pages, 10 figures, LaTeX fil

Influência do sistema de condução do vinhedo no índice de polifenóis totais, teor de antocianinas e intensidade de cor de uvas cabernet sauvignon (vitis vinifera l.)

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Físicas e Matemáticas. Curso de Química.Neste trabalho foi avaliada a influência da condução do vinhedo no índice de polifenóis totais, teor de antocianinas monoméricas totais e intensidade de cor em uvas Cabernet Sauvignon (Vitis vinifera L.) safra 2005, provenientes de um vinhedo situado a 1200m de altitude da região de São Joaquim (SC) com plantas de aproximadamente seis anos de idade e clone R-5 cultivadas em dois sistemas de condução: Espaldeira e Lira. A determinação do índice de polifenóis totais foi realizada através de método espectrofotométrico, baseado na reação com o reagente de Folin-Ciocalteau descrito por Kiralp & Toppare, 2005. As antocianinas monométricas totais foram determinadas pelo método do pH diferencial descrito por Giusti & Wrolstad, 2001. Realizou-se a determinação da intensidade de cor (IC), segundo GLORIES, 1984, com leitura das absorvâncias em comprimentos de onda específicos (420nm, 520nm e 620nm). Os valores referentes ao índice de polifenóis totais (IPT), teor de antocianinas monoméricas totais (AT) e intensidade de cor (IC) das amostras provenientes de videiras conduzidas em sistema Lira foram superiores aos encontrados em uvas provenientes do sistema de condução em Espaldeira, isto pode ser justificado pelo microclima proporcionado neste sistema

Estudio comparativo del desempeño reproductivo de vacas cebuinas con diferentes periodos posparto bajo un programa de monta rotativa

Proyecto de Graduación (Bachiller en Ingeniería en Agronomía) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería en Agronomía, 2006.Esta investigación se llevó a cabo para evaluar el efecto reproductivo de un sistema de empadre rotativo, que fue aplicado a 78 hembras cebuínas, 41 animales en posparto largo (176 ± 107 días posparto, PPL) y 37 en posparto corto (promedio de 62 ± 8 días luego del parto, PPC). En el grupo PPL, el 61% (25/41) estaban ciclando antes de exponerlas a los toros mientras solo el 38% (14/37) en el grupo PPC. Las vacas fueron manejadas en un sistema de monta rotacional, para lo cual se usaron seis toros Brahman con previa experiencia sexual, los cuales fueron ordenados en parejas en tres grupos (A-B, C-D y E-F). Las hembras fueron expuestas a cada par de toros por periodos de tres semanas, con una semana de receso entre cada periodo, en donde las hembras estaban sin presencia de machos. En el grupo PPL, el porcentaje de gestación para los toros A-B fue de un 68% (28/41), los toros C-D alcanzaron un 38% (5/13) y los toros E-F un 38% (3/8). Por otro lado, al interactuar con las vacas de posparto corto, los toros A-B obtuvieron un porcentaje de gestación del 32% (12/37), los toros C-D un 52 (13/25) y por último los toros E-F un 54% (7/13). El porcentaje de preñez obtenido por el par de toros A-B fue diferente entre los grupos PPL y PPC, no obstante, para los toros C-D y E-F fueron similares. El rango de preñez fue diferente en las tres primeras semanas del apareamiento en el grupo PPL debido al alto número de hembras que se preñaron en las tres primeras semanas del estudio. En contraste, la mayor cantidad de hembras diagnosticadas gestantes en el grupo PPC se dio en las últimas seis semanas. Este estudio sugiere que el desempeño reproductivo de las parejas de toros en un programa rotacional evaluando el porcentaje de gestación es similar (85 % en el PPL y un 81% en el PPC). Sin embargo, el tiempo tomado por las hembras para lograr la preñez y por ende el desempeño de los toros, esta relacionado con el promedio de número de días posparto de las vacas.Instituto Tecnológico de Costa Rica Sede San Carlos. Escuela de Ingeniería em Agronomía

Some Factors Associated With the Effectiveness of the Agricultural Production Component in Areas of Integrated Rural Development in Colombia as Perceived by Farmers (Crop Technology).

This study was conducted in two Integrated Rural Development Districts in Colombia; South Tolima and Fusagasuga. Its specific objectives were: (1) To determine the extent to which: (a) the factors included in the agricultural production component of the DRI program (research, extension, credit, marketing), in addition to farmland and climate were limiting crop productivity; (b) the DRI program was effectively transferring crop technology; (c) farmers adopted recommended crop technology; (2) To determine: (a) some of the reasons that limited adoption of agricultural technology; (b) changes in crop production; (c) some relevant characteristics of the DRI credit and marketing programs; (d) farmers\u27 satisfaction related to the DRI technical assistance, credit, and marketing programs; (e) the extent of association between the dependent variables, adoption of technology and crop production, and the independent variables effectiveness in transferring technology, difficulty in obtaining credit, difficulty in marketing crop production, as well as between crop production and adoption of technology. Sixty cooperating farmers were selected at random from each district for a total sample of 120 respondents. Data were collected through an interview schedule, and statistically analyzed. The major conclusions were as follows: (1) Some progress in agricultural production were evident in both districts as supported by some improvements in crop production. Nevertheless, agricultural development has been taking place slowly and it is not yet at the desired level. (2) Appropriate conditions of research, extension, credit, marketing, farmland, and climate were not present in the most appropriate mix in order to maximize productivity and accelerate development. These factors affected productivity and development to a different extent in each district. Inappropriate marketing conditions were perceived by the farmers as the principal constraint to crop productivity, while credit was perceived as the least limiting factor. (3) In order to further accelerate agricultural development, greater emphasis is needed on generating appropriate crop technologies, adapted to local farming conditions, on proper and effective technology transfer to the farmers. Stable and effective local organizations are necessary for these conditions to exist, particularly to support marketing activities. Risk and uncertainty to the farmer must be reduced as much as possible so that change can be facilitated

Identity, Positioning, Brand Image and Brand Equity Comparison.

The management of marketing has as presupposition the understanding of the relations between market and consumption, as well as, the concepts related to the maximization of the results of the company. In this way, an article was elaborated in search of the understanding of the existing relations between brand identity, positioning, brand image and brand equity. In this context, qualitative-quantitative research was sought to describe the existing relationships between concepts, as well as the conceptual and managerial gaps arising from their management. As a result of this work we have the analysis of the conceptual and operational gaps of these concepts

Floristic survey of the herbaceous-shrub layer of a gallery forest in Alto Paraíso de Goiás - Go, Brazil

Flowering species of the herbaceous and shrubby layer were sampled in a gallery forest at Portal da Chapada, Alto Paraíso de Goiás-GO in the Chapada dos Veadeiros during 12 months growing within 4.5 meters on either side of a raised pathway 2.4 Km long. The collections were included to University of Brasilia Herbarium (UB). A total of 138 species (103 genera and 40 families) were recorded; the most species-rich families were Asteraceae (22), Poaceae (14), Rubiaceae (12), Fabaceae (11) and Melastomataceae (7). The richest family in number of genera was Asteraceae (19), followed by Poaceae (8), Fabaceae (8) and Rubiaceae (7). The results showed a meaningful increase in the Chapada dos Veadeiros flora, especially considering the herbaceous-shrubby layer of the gallery forests (223.6%). Despite the richness of the flora, the number of endemics species in the Goiás State was only 1.5%