A note on the invariant distribution of a quasi-birth-and-death process

The aim of this paper is to give an explicit formula of the invariant distribution of a quasi-birth-and-death process in terms of the block entries of the transition probability matrix using a matrix-valued orthogonal polynomials approach. We will show that the invariant distribution can be computed using the squared norms of the corresponding matrix-valued orthogonal polynomials, no matter if they are or not diagonal matrices. We will give an example where the squared norms are not diagonal matrices, but nevertheless we can compute its invariant distribution

Induction of stimulative parthenocarpy in Vitis vinifera L.

Stimulative parthenocarpy was induced in two varieties of Vitis vinifera L. Flame Tokay and Rose Muscat (local variety) out of eight varieties studied.In F l a m e T o k a y the delay or inhibition of bhe abscission of the calyptra and parthenocarpic development of the berries, was obtained with pre-bloom treatments (3 days before beginning of bloom) of 4CPA 30 ppm + KGA3 30 ppm. Induction and growth ,of parthenocarpic berries was most pronounced after post-bloom sprays (7 days after the end of bloom) with BA 1500 ppm + KGA3 80 ppm or 4CPA 30 ppm. A parthenocarpic development of the berries was also obtained with postbloom treatments of KGA3 at concentrations of 50 to 100 ppm. BA (Benzyladenine) alone had only a slight effect on the development of parthenocarpic berries. However, the results were surprisingly satisfactory when applied in combination with gibberellin (KGA3 80 ppm) or auxins. Treatments at bloom or after bloom with BA 800 ppm + KGA3 80 ppm increased bhe number of berries and cluster weight. Applications of BA 800 ppm + KGA3 80 ppm to Rose Musca t at the beginning of bloom resulted in clusters with practically all berries seedless. The artificially accelerated growth of the berries may provoke abortion of all the recently fecundated ovules and the non viability of the not fecundated ones. Clusters of the treated plants with an average of 520 flowers originated 501 parbhenocarpic berries (96%), whereas the control with an average 635 flowers per cluster gave a percentage of seeded + seedless berries of 14% only {95 berries per cluster). BA applied with auxin or gibberellin-like substances in full-bloom or after bloom produced seedless berries, which were smaller in size than the seeded berries of unsprayed clusters

Properties of Matrix Orthogonal Polynomials via their Riemann-Hilbert Characterization

We give a Riemann-Hilbert approach to the theory of matrix orthogonal polynomials. We will focus on the algebraic aspects of the problem, obtaining difference and differential relations satisfied by the corresponding orthogonal polynomials. We will show that in the matrix case there is some extra freedom that allows us to obtain a family of ladder operators, some of them of 0-th order, something that is not possible in the scalar case. The combination of the ladder operators will lead to a family of second-order differential equations satisfied by the orthogonal polynomials, some of them of 0-th and first order, something also impossible in the scalar setting. This shows that the differential properties in the matrix case are much more complicated than in the scalar situation. We will study several examples given in the last years as well as others not considered so far

Furrow and Ridge Soil Nitrogen Mineralization in a Surface Irrigated Artichoke Field

[EN] Quantitative knowledge of soil organic nitrogen net mineralization (NNM) in field conditions is crucial to optimize N fertilization of crops. In a field fertilization trial of artichokes 48 PE tubes were inserted to 20 cm depth in the soil in plant row and irrigation furrows and soil samples were periodically taken during two and a half months to determine NNM. A parallel essay with disturbed samples from the same procedence was carried out in the laboratory at 25ºC and 10 kPa soil water tension. Soil sample position (ridge and furrow) did not significantly determined NNM in the laboratory essay. Although NNM (obtained from laboratory incubation and corrected to field soil temperature and moisture monitored during the experimental period) overpredicted measured field NNM, matching of both was better than those reported in other studies. NNM rate for the 76 days period of incubation predicted from lab data was 22.9 kg N/ ha x 0.1 m while corresponding field values corrected by Br- or Cl- mass balance were 10% and 20% lower respectively in ridge position and under 40% lower by either method in furrow position.The research reported in this paper was supported by a fund from CICYT-INIA (project RTA01-117-C2-2)Lidón, A.; Bautista, I.; De La Iglesia, F.; Oliver Talens, J.; Llorca, R.; Cruz-Romero, G. (2006). Furrow and Ridge Soil Nitrogen Mineralization in a Surface Irrigated Artichoke Field. Acta Horticulturae. (700):71-74. https://doi.org/10.17660/ActaHortic.2006.700.7S717470

Effect of disease prevalence and growth stage on symptom severity in the Turnip mosaic virus – Arabidopsis thaliana pathosystem

In response to stresses, plants are capable of communicating their physiological status to other individuals in the community using several chemical cues. Nearby receivers then adjust their own homeostasis to increase resilience. The majority of studies to date have concentrated on the communication of abiotic stressors (e.g., salinity or drought) or herbivory. Less attention has been paid to the role of communication during microbial infections and almost nothing has focused on viruses. Here we investigated the effect that the prevalence of a turnip mosaic virus in a community of Arabidopsis thaliana has on the severity of symptoms developed in a group of receivers. First, we looked at the influence of two factors on the kinetics of symptom progression in the receivers, namely the prevalence of infection among emitters and the growth stage of the receiver plants at inoculation. We found that young receiver plants developed milder symptoms than older ones, and that high infection prevalence resulted in slower disease progression in receivers. Second, we tested the possibility that jasmonates could act as chemical signaling cues. To do this, we examined the kinetics of symptom progression in jasmonate-insensitive and wild-type plants. The results showed that the protective effect vanished in the mutant plants. Third, we investigated the possibility that root communication could also be relevant. We found that the kinetics of symptom progression across receivers was further slowed down in an age-dependent manner when plants were planted in the same pot. Together, these preliminary findings point to a potential function for disease prevalence in plant communities in regulating the severity of symptoms, this effect being mediated by some volatile organic compounds

Parenting Styles, Internalization of Values and Self-Esteem: A Cross-Cultural Study in Spain, Portugal and Brazil

The present study analyzes the impact of parenting styles on adolescents’ self-esteem and internalization of social values in three countries, Spain, Portugal and Brazil. The sample of the study was comprised of 2091 adolescents from Spain (n = 793), Portugal (n = 675), and Brazil (n = 623) from 12–18 years old (52.1% females). The four types of parenting styles, authoritative, indulgent, authoritarian and neglectful, were measured through the warmth and strictness dimensions of the Scale of Parental Socialization ESPA29. The two criteria variables were captured with the five dimensions of the AF5, Five-Factor Self-Concept Questionnaire, and with self-transcendence and conservation Schwartz values. Results confirm emergent research in parenting socialization: the use of parental warmth is evidenced as key for adolescent self-esteem and internalization of social values in the three countries analyzed. Indulgent and authoritative parenting (both characterized by parental warmth) are associated with the highest value internalization in the three countries. Furthermore, indulgent parenting (use of warmth) is associated with the highest adolescent self-esteem, overcoming authoritative parenting (use of warmth and strictness). The influence of parenting over adolescent self-esteem and values internalization is maintained independent of the differences in self-esteem and value priorities observed in the cultural context, the sex and age of the participants.info:eu-repo/semantics/publishedVersio