An investigation of passive control methods for shock-induced separation at hypersonic speeds

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76765/1/AIAA-1992-2725-533.pd

Hedgerow olive orchards: reality or utopia?

Actualmente las plantaciones de olivar tienen unas densidades que no suelen superar los 330 olivos por hectárea. El mayor coste su cultivo se produce en la recolección, donde se necesita una gran cantidad de mano de obra. Recientemente ha surgido un nuevo tipo de plantaciones cuyas densidades se acercan a las 2000 plantas por hectárea y donde los olivos se disponen en setos continuos separados unos 3,5 m. La mayor ventaja de este tipo de plantaciones es su recolección totalmente mecanizada, mediante máquinas cabalgadoras que pasan por encima de los setos, en un sistema muy parecido al usado en la vid. Además, estas plantaciones son de muy temprana entrada en producción y muy productivas, al menos en los primeros años. La variedad que se utiliza, casi en exclusiva, para este tipo de plantaciones es ‘Arbequina’. En el presente trabajo se describen los resultados de un ensayo comparativo de variedades que se estableció en el año 2000 y del que se han recogido ya 4 cosechas. Este ensayo incluye las variedades ‘Arbequina’, ‘Arbequina i-18’, ‘Arbosana’, ‘Koroneiki’, ‘Fs-17’ y ‘UC 2-35’. De ellas, ‘Arbequina’ y ‘Arbosana’ han sido las más productivas y ‘UC 2-35’ la menos vigorosa de las ensayadas. También se describen los resultados de un ensayo comparativo de densidades desde 754 a 2580 plantas/ha que fue establecido en el año 1999. Hasta ahora, la densidad más productiva parece ser la de 2000 plantas/ ha. Habrá que esperar a los próximos años para tener resultados más definitivos sobre éstos ensayos ya que es de esperar que a partir de ahora es cuando aparezcan los problemas relacionados con la competencia entre árboles. En conclusion, en un escenario donde las ayudas de la Unión Europea van a ir disminuyendo progresivamente, y donde la mano de obra es cada vez más difícil de encontrar, la capacidad real de este tipo de plantaciones de ser rentables a largo plazo determinará el futuro éxito de las mismas.Nowadays, olive orchards have a densities not higher than 330 trees/ha. The major cost correspond to harvest operations, which is very labour demanding. Recently, a new type of olive plantations with densities around 2.000 tress/ha has appeared. The major advantage of this type of plantations is their totally mechanised harvest, by vineyards straddle-harvesting machines.These plantations have a very early bearing and very productive, at least in the first years. The most common cultivar used is ‘Arbequina’. In the present work, data of the first four harvest of a variety comparative trial are reported. This trial include ‘Arbequina’, ‘Arbequina i-18’, ‘Arbosana’, ‘Koroneiki’, ‘Fs- 17’ y ‘UC 2-35’ cultivars. From the ‘Arbequina’ and ‘Arbosana’ had been the most productive and ‘UC 2-35’ the less vigorous. Results of a trial testing densities between 780 and 2580 trees/ha is also described. Up to now, the higher densities have been the most productive ones. However, more definitive results can be obtained in the coming years, when problems of competence among trees started to appear. In summary, as in the near future is expected that the subsides from the EU are going to be greatly reduced and the labour for harvesting is difficult to find, the ability to this type of plantations to be profitable at long term will determine their success

Updated single and dual crop coefficients for tree and vine fruit crops

ReviewThe present study reviews the research on the FAO56 crop coefficients of fruit trees and vines performed over the past twenty years. The main objective was to update information and extend tabulated single (Kc) and basal (Kcb) standard crop coefficients. The selection and analysis of the literature for this review have been done to consider only studies that adhere to FAO56 method, computing the reference ET with the FAO Penman– Monteith ETo equation and field measuring crop ET with proved accuracy. The crops considered refer to vine fruit crops, berries and hops, temperate climate evergreen fruit trees, temperate climate deciduous fruit trees and, tropical and subtropical fruit crops. Papers satisfying the conditions expressed above, and that studied the crops under pristine or appropriate eustress conditions, were selected to provide for standard Kc and Kcb data. Preference was given to studies reporting on the fraction of ground cover (fc), crop height (h), planting density, crop age and adopted training systems. The Kc and Kcb values obtained from the selected literature generally show coherence relative to the crop biophysical characteristics and reflect those characteristics, mainly fc, h and training systems. The ranges of reported Kc and Kcb values were grouped according to crop density, particularly fc and h, and were compared with FAO56 (Allen et al., 1998) previously tabulated Kc and Kcb values, as well as by Allen and Pereira (2009) and Jensen and Allen (2016), which lead to define update indicative standard Kc and Kcb values. These values are aimed for use in crop water requirement computations and modeling for irrigation planning and scheduling, thus also aimed at supporting improved water use and saving in orchards and vinesinfo:eu-repo/semantics/publishedVersio

Risk Allocation in Toll Highway Concessions in Spain: Lessons from Economic Recession

Spain has a long tradition of encouraging toll highways by granting concessions to private companies. Concessions in Spain have been characterized by a willingness to transfer considerable risk to the private sector. Traffic demand, acquisition of the right-of-way, and financial risk have often been allocated to the private sector. From 1996 to 2011, 16 toll highway concessions, covering a total distance of 835 km, were awarded by the central government of Spain with this approach. Some of those highways started their operations just before the economic recession began. The recession had negative consequences for Spain's economy. The gross domestic product per capita plummeted, and the unemployment rate increased from 9% to 20% of the working population in just 2 years. The recession also had severe consequences for the economic performance of toll highway concessions. Traffic levels declined at a much greater rate than did the gross domestic product. In addition, the conditions imposed by the financial markets on borrowers became much stricter because of the liquidity crisis. This study analyzes the impact that the economic recession ultimately had on the performance of toll highway concessions in Spain and the actions that the government adopted to avoid the bankruptcy of the concessionaires. It was found that the economic recession helped identify some deficiencies in how risk had been allocated in Spain. The measures that both Spain and the European Union are adopting so as to improve risk allocation are discussed

Estudio fenológico y caracterización morfológica de variedades tradicionales de manzano y melocotonero

Las variedades locales de frutales seleccionadas a lo largo de los años por los agricultores, son muy interesantes para preservar la biodiversidad y los recursos fitogenéticos, ya que presentan unas características organolépticas peculiares y un valor cultural irremplazable. En 2007 se inició un trabajo de recuperación de variedades tradicionales de frutales en Andalucía (Proyecto INIA, RF2007-00027- C06-05) que contempla su prospección, localización, recogida de material vegetal, caracterización morfológica y molecular, multiplicación, documentación y mantenimiento en colección. En este trabajo se han caracterizado morfológicamente mediante caracteres UPOV las flores, hojas y ramos de un año, de cinco variedades tradicionales de manzano (Malus x domestica Borkh.) y dos de melocotonero [Prunus persica (L) Batsch], no estudiadas con anterioridad. Se ha evaluado la floración en la campaña 2011 y se han realizado los fenogramas correspondientesMICINN, INIA y Fondos FEDE

Creedy, Jean Iris

The final stage of leaf ontogenesis is represented by senescence, a highly regulated process driven by a sequential cellular breakdown involving, as the first step, chloroplast dismantling with consequent reduction of photosynthetic efficiency. Different processes, such as pigment accumulation, could protect the vulnerable photosynthetic apparatus of senescent leaves. Although several studies have produced transcriptomic data on foliar senescence, just few works have attempted to explain differences in red and green leaves throughout ontogenesis. In this work, a transcriptomic approach was used on green and red leaves of Prunus cerasifera to unveil molecular differences from leaf maturity to senescence. Our analysis revealed a higher gene regulation in red leaves compared to green ones, during leaf transition. Most of the observed DEGs were shared and involved in transcription factor activities, senescing processes and cell wall remodelling. Significant differences were detected in cellular functions: genes related to photosystem I and II were highly down-regulated in the green genotype, whereas transcripts involved in flavonoid biosynthesis, such as UDP glucose-flavonoid-3-O-glucosyltransferase (UFGT) were exclusively up-regulated in red leaves. In addition, cellular functions involved in stress response (glutathione-S-transferase, Pathogen-Related) and sugar metabolism, such as three threalose-6-phosphate synthases, were activated in senescent red leaves. In conclusion, data suggests that P. cerasifera red genotypes can regulate a set of genes and molecular mechanisms that cope with senescence, promoting more advantages during leaf ontogenesis than compared to the green ones