3,217 research outputs found
Grapevine (Vitis vinifera L.) promoter analysis by biolistic-mediated transient transformation of cell suspensions
Expression of alcohol dehydrogenase promoters from Vitis vinifera L. and Arabidopsis thaliana was investigated in homologous and heterologous cell systems after bombardment of chimeric genes. The effect of several parameters including wounding, DNA delivery and construct type on luciferase/beta-glucuronidase activities was evaluated. In parallel, alcohol dehydrogenase activity was assayed in normal and gaseous nitrogen-treated cells. Compared to A. thaliana, results showed large differences in reporter gene activity according to the Adh promoter leader sequence and the cell suspension system. The V. vinifera cell system was found to be appropriate to investigate Adh promoter functioning. A novel protocol, based on transient genetic transformation of grape-One cells by biolistic is proposed to study grapevine promoter expression, either in air or in response to anaerobiosis.
Some results on B-matrices and doubly B-matrices
A real matrix with positive row sums and all its off-diagonal elements bounded above by their corresponding row means was called in [4] a B-matrix. In [5], the class of doubly B-matrices was introduced as a generalization of the previous class. We present several characterizations and properties of these matrices and for the class of B-matrices we consider corresponding questions for subdirect sums of two matrices (a general ‘sum’ of matrices introduced in [1] by S.M. Fallat and C.R. Johnson, of which the direct sum and ordinary sum are special cases), for the Hadamard product of two matrices and for the Kronecker product and sum of two matrices.Fundação para a Ciência e Tecnologia (FCT)Ministerio de Ciencia y Tecnología (Espanha
The completion problem for N-matrices
An matrix is called an -matrix if all principal minors are negative. In this paper, we are interested in -matrix completion problems, that is, when a partial -matrix has an -matrix completion. In general, a combinatorially or non-combinatorially symmetric partial -matrix does not have an -matrix completion. Here, we prove that a combinatorially symmetric partial -matrix has an -matrix completion if the graph of its specified entries is a 1-chordal graph. We also prove that there exists an -matrix completion for a partial -matrix whose associated graph is an undirected cycle.Fundação para a Ciência e a Tecnologia (FCT) – Programa Operacional “Ciência, Tecnologia, Inovação” (POCTI)
DGI - BFM2001-0081-C03-0
Two extensions of consumer surplus
We study consumer surplus in a single market when (a) there is a lower bound in the
consumption of the outside good and (b) the weights in the social welfare function given
to consumers and firms are different. We assume quasilinear utility. When the lower
bound constraint on the consumption of the outside good is binding, income effects
arise in demand. In some cases, Cournot equilibrium output is below equilibrium
output without this constraint because the constraint makes demand less elastic.When
the weights given to consumers and firms are not identical, social welfare is not
necessarily concave and profits might be negative at the unrestricted optimum. We
characterize social welfare optimum with a bound on maximum losses in a class of
utility functions. We offer a formula to find the percentage of welfare losses due to
oligopoly in this case
A Bendixson-Dulac theorem for some piecewise systems
The Bendixson-Dulac Theorem provides a criterion to find upper bounds for the number of limit cycles in analytic differential systems. We extend this classical result to some classes of piecewise differential systems. We apply it to three different Liénard piecewise differential systems ¨ x+f±(x)˙ x+x = 0. The first is linear, the second is rational and the last corresponds to a particular extension of the cubic van der Pol oscillator. In all cases, the systems present regions in the parameter space with no limit cycles and others having at most one
N_0 completions on partial matrices
An matrix is called an -matrix if all its principal minors are nonpositive. In this paper, we are interested in -matrix completion problems, that is, when a partial -matrix has an -matrix completion. In general, a combinatorially or non-combinatorially symmetric partial -matrix does not have an -matrix completion. Here, we prove that a combinatorially symmetric partial -matrix,
with no null main diagonal entries, has an -matrix completion if the graph of its specified entries is a 1-chordal graph or a cycle. We also analyze the mentioned problem when the partial matrix has some null main diagonal entries.Fundação para a Ciência e a Tecnologia(FCT) através do programa POCTISpanish DGI grant number MTM2007-6447
Sizing of a reversible magnetic heat pump for the automotive industry
[EN] This paper focuses on the design of an innovative air-conditioning system, namely a magnetocaloric air-conditioner for an electric minibus. An integrated design of the complete system is necessary, as the hot and cold side of the regenerator will work under dynamic conditions which depend on the instantaneous thermal load in the cabin.
In order to assist the design of the system, a dynamic model has been developed for the cabin, the hydraulic loops and heat exchangers, and the magnetocaloric unit. This paper presents (i) a description of the dynamic models, (ii) an analysis of the operating conditions of the magnetocaloric unit and (iii) a discussion on the design of the magnetocaloric air-conditioner. The results show that the electric minibus requests 1.60 kW of cooling power over a span of 37 K in cooling mode, and 3.39 kW of heating power over a span of 40 K.This work has been supported by the European Commission under the 7th European Community framework program as part of the ICE project "MagnetoCaloric Refrigeration for Efficient Electric Air-Conditioning", Grant Agreement no. 265434. B. Torregrosa-Jaime acknowledges the Spanish Science and Innovation Ministry (Ministerio de Ciencia e Innovacion) for receiving the Research Fellowship FPU ref. AP2010-2160.Torregrosa Jaime, B.; Corberán Salvador, JM.; Vasile, C.; Muller, C.; Risser, M.; Payá Herrero, J. (2014). Sizing of a reversible magnetic heat pump for the automotive industry. International Journal of Refrigeration. 37:156-164. https://doi.org/10.1016/j.ijrefrig.2013.06.018S1561643
Effect of different 3’ flanking regions on the activity of the Vitis vinifera alcohol dehydrogenase 2 promoter
3’untranslated regions (3' UTR) are isogene specific regions which contain sequences likely playing an important role in gene expression. To evaluate the importance of these regions on Vitis vinifera alcohol dehydrogenase 2 (VvAdh2) expression, we designed expression cassettes containing the luciferase reporter gene under the VvAdh2 or CaMV 35S promoters and flanked by different 3’ UTRs. Luciferase activity monitoring was performed through transient expression experiments, using biolistic on Cabernet Sauvignon suspension cells. Results showed that absence of the 3’ region had a strong down-regulating effect on the VvAdh2 promoter activity (but not on the CaMV 35S promoter activity). The nature of the flanking 3' UTR was shown to influence expression cassette activity. Whatever the promoter, VvAdh1 and VvAdh2 terminators had similar effect on expression of luciferase in air leading to an activity level very close to that of CaMV 35S terminator. Under anaerobiosis, luciferase expression was strongly increased with all terminators, VvAdh6 3'-end inducing the highest level of expression. Functional constructs with VvAdh2 promoter and VvAdh terminators designed in this study could be used wherever grapevine-homologous, stress-stimulated cassettes should be of interest
El docudrama contemporáneo: rasgos configuradores
El docudrama se ha convertido en un modelo génerico y narrativo de creciente importancia en la ficción contemporánea y con un impacto cada vez mayor en España, sobre todo en su forma televisiva. Sin embargo, en nuestro país, su investigación académica es todavía relativamente escasa, en comparación con la atención que ha recibido en el mundo angloparlante. Este artículo ofrece una primera aproximación a la definición del docudrama, basado en dos tipos de análisis. En la primera parte, realizamos un análisis contextual, que revisa las características básicas de las principales tradiciones –la británica y la norteamericana– que históricamente han configurado este tipo de obras. En la segunda, se analizan los elementos de carácter textual, basándose en el estudio de sus aspectos ficcionales y documentales.
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The docudrama has become a narrative and genre model of increasing importance in contemporary fiction and with a growing impact in Spain, above all in its televised form. However, in our country, academic research on the docudrama is still relatively limited in comparison with the attention which it has received in the English-speaking world. The paper we present here offers an initial approach to the definition of the docudrama, based on two different types of analysis. In the first part, we consider contextual analysis, which analyzes the basic features of the principal traditions —the British and the North American— which have historically shaped these products. In the second, we analyze elements of a textual nature, based on their dual fictional and documental aspects
Analysis of the transcript levels of VvAdh1, VvAdh2 and VvGrip4, three genes highly expressed during Vitis vinifera L. berry development
Well defined promoter sequences are required for the targeted expression of genes in transgenic grapevines. This paper describes a detailed study of the expression of three genes with potentially useful promoters. We have used real-time RT-PCR to evaluate the transcript levels of VvAdh1, VvAdh2 and VvGrip4 genes in various tissues (root, bud, tendril, inflorescence, fruit and embryogenic callus) of Vitis vinifera L. at different stages of development. Transcript levels of the three genes were highest in berry tissues but each had a distinct pattern of expression. VvAdh1 showed higher transcript levels during the early stages of berry development, while levels of VvAdh2 and VvGrip4 were higher during ripening. However, none of these genes was expressed in a strictly fruit-specific manner. In particular, significant levels of VvAdh1 and VvGrip4 transcripts were observed during late tendril development and in the inflorescence, respectively. Transcript levels of all three genes were similar in both flesh and skin, indicating no tissue-specificity within the berry. Promoter sequences of the VvAdh1, VvAdh2 and VvGrip4 genes could be very useful to drive ectopic gene expression in berries of transgenic plants
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