Performance and radial distribution profiles of a variable flow rate sprinkler developed for precision irrigation

Variable rate sprinklers (VRS) have been developed to promote localized water application of irrigated areas. In Precision Irrigation, VRS permits better control of flow adjustment and, at the same time, provides satisfactory radial distribution profiles for various pressures and flow rates are really necessary. The objective of this work was to evaluate the performance and radial distribution profiles of a developed VRS which varies the nozzle cross sectional area by moving a pin in or out using a stepper motor. Field tests were performed under different conditions of service pressure, rotation angles imposed on the pin and flow rate which resulted in maximal water throw radiuses ranging from 7.30 to 10.38 m. In the experiments in which the service pressure remained constant, the maximal throw radius varied from 7.96 to 8.91 m. Averages were used of repetitions performed under conditions without wind or with winds less than 1.3 m s-1. The VRS with the four stream deflector resulted in greater water application throw radius compared to the six stream deflector. However, the six stream deflector had greater precipitation intensities, as well as better distribution. Thus, selection of the deflector to be utilized should be based on project requirements, respecting the difference in the obtained results. With a small opening of the nozzle, the VRS produced small water droplets that visually presented applicability for foliar chemigation. Regarding the comparison between the estimated and observed flow rates, the stepper motor produced excellent results.

Variable rotational line broadening in the Be star Achernar

Aims. The main theoretical problem for the formation of a Keplerian disk around Be stars is how angular momentum is supplied from the star to the disk, even more so since Be stars probably rotate somewhat subcritically. For instance, nonradial pulsation may transport angular momentum to the stellar surface until (part of) this excess supports the disk-formation/replenishment. The nearby Be star Achernar is presently building a new disk and o ers an excellent opportunity to observe this process from relatively close-up. Methods. Spectra from various sources and epochs are scrutinized to identify the salient stellar parameters characterizing the disk life cycle as defined by H emission. The variable strength of the non-radial pulsation is confirmed, but does not a ect the other results. Results. For the first time it is demonstrated that the photospheric line width does vary in a Be star, by as much as v sin i . 35 km However, unlike assumptions in which a photospheric spin-up accumulates during the diskless phase and then is released into the disk as it is fed, the apparent photospheric spin-up is positively correlated with the appearance of H line emission. The photospheric line widths and circumstellar emission increase together, and the apparent stellar rotation declines to the value at quiescence after the H line emission becomes undetectable

Estudio del comportamiento de un sistema de recuperación de energía en una planta de ósmosis inversa en condiciones de funcionamiento de régimen variable, fundamentado en el empleo de un sistema PX

[ES] La obtención de agua potable mediante técnicas de desalinización está muy extendida en canarias, para ello se requieren elevados consumos de energía que pueden disminuirse incorporando un recuperador de energía. En este trabajo se ha estudiado el comportamiento de un sistema de recuperación de energía, tipo PX, bajo condiciones variables de energía para una planta de o.I. de 115m3/día, de esta manera se podrá profundizar en el comportamiento de estos sistemas en régimen variable. El concepto nuevo que se introduce en este proyecto es el diseño de sistemas de desalinización que puedan funcionar eficientemente con suministro de potencia variable. Esto implica la integración directa de la energía renovable y la ósmosis inversa sin dispositivo alguno para el almacenamiento de energía.

Estrategia óptima de reemplazamiento de un sistema de fallos reparables y tasa de producción variable

[ES]Se considera un sistema formado por una estructura principal y otra secundaria productora de ítems. Un fallo en la estructura principal puede producir una disminución de la producción en el subsistema productor de ítems. Los fallos en la estructura principal son los únicos que pueden ser reparados mínimamente. Para una estructura fija de beneficios, se determina la estrategia óptima de reemplazamiento del sistema y se muestra un estudio de simulación de un ejemplo.

The structure of planktonic communities under variable coastal upwelling conditions off Cape Ghir (31ºN), in the Canary Current System (NW Africa)

Universidad de Las Palmas de Gran Canaria. Facultad de Ciencias del Mar. Programa de doctorado en Oceanografía. Diploma de Estudios Avanzados

Identification of Drosophila heart-specific Cis-Regulatory Modules under Hox control

Cardiac morphogenesis is a complex process governed by evolutionarily conserved transcription factors and signaling molecules. The Drosophila cardiac tube is linear, made of 52 pairs of cardiomyocytes (CMs), which express specific transcription factor genes that have human homologues implicated in Congenital Heart Diseases (CHDs) (NKX2-5, GATA4 and TBX5). The Drosophila cardiac tube is linear and composed of a rostral portion named aorta and a caudal one called heart, distinguished by morphological and functional differences controlled by Hox genes, key regulators of axial patterning. Overexpression and inactivation of the Hox gene abdominal-A (abd-A), which is expressed exclusively in the heart, revealed that abd-A controls heart identity. The aim of our work is to isolate the heart-specific cisregulatory sequences of abd-A direct target genes, the realizator genes granting heart identity. In each segment of the heart, four pairs of cardiomyocytes (CMs) express tinman (tin), homologous to NKX2-5, and acquire strong contractile and automatic rhythmic activities. By tyramide amplified FISH, we found that seven genes, encoding ion channels, pumps or transporters, are specifically expressed in the Tin-CMs of the heart. We initially used online available tools to identify their heart-specific cisregutatory modules by looking for Conserved Non-coding Sequences containing clusters of binding sites for various cardiac transcription factors, including Hox proteins. Based on these data we generated several reporter gene constructs and transgenic embryos, but none of them showed reporter gene expression in the heart. In order to identify additional abd-A target genes, we performed microarray experiments comparing the transcriptomes of aorta versus heart and identified 144 genes overexpressed in the heart. In order to find the heart-specific cis-regulatory regions of these target genes we developed a new bioinformatic approach where prediction is based on pattern matching and ordered statistics. We first retrieved Conserved Noncoding Sequences from the alignment between the D.melanogaster and D.pseudobscura genomes. We scored for combinations of conserved occurrences of ABD-A, ABD-B, TIN, PNR, dMEF2, MADS box, T-box and E-box sites and we ranked these results based on two independent strategies. On one hand we ranked the putative cis-regulatory sequences according to best scored ABD-A biding sites, on the other hand we scored according to conservation of binding sites. We integrated and ranked again the two lists obtained independently to produce a final rank. We generated nGFP reporter construct flies for in vivo validation. We identified three 1kblong heart-specific enhancers. By in vivo and in vitro experiments we are determining whether they are direct abd-A targets, demonstrating the role of a Hox gene in the realization of heart identity. The identified abd-A direct target genes may be targets also of the NKX2-5, GATA4 and/or TBX5 homologues tin, pannier and Doc genes, respectively. The identification of sequences coregulated by a Hox protein and the homologues of transcription factors causing CHDs, will provide a mean to test whether these factors function as Hox cofactors granting cardiac specificity to Hox proteins, increasing our knowledge on the molecular mechanisms underlying CHDs. Finally, it may be investigated whether these Hox targets are involved in CHDs.