1,282 research outputs found
Evaluation of the METRIC model for mapping energy balance components and actual evapotranspiration for a super-intensive drip-irrigated olive orchard
A field experiment was carried out to evaluate the METRIC (Mapping EvapoTranspiration at high Resolution Internalized with Calibration) model for mapping net radiation (Rni), soil heat flux (Gi), sensible heat flux (Hi), latent heat flux (LEi), actual evapotranspiration (ETa) and crop coefficient (Kc) of a superintensive drip-irrigated olive (Olea europeae L. cv Arbequina) orchard located in Pencahue Valley, Region del Maule, Chile (35 23â LS; 71 44â LW; 96 m above sea level). The study was conducted in an experimental plot of 21.1 hectares using 9 satellite images (Landsat 7 ETM+) acquired on clear sky days during 2011/2012 and 2012/2013 growing seasons. Specific functions to estimate Gi, leaf area index (LAI) and aerodynamic roughness length for momentum transfer (zom) were incorporated in the standard METRIC model. The performance of the METRIC model was evaluated at the time of satellite overpass using measurements of LE and H obtained from an eddy correlation system. Validation indicated that METRIC using the specific functions was able to estimate Rn, G, H, LE, ETa, and Kc with errors less than +5%
Los motines del hambre en Castilla la Vieja en el siglo XIX
El trabajo relata los acontecimientos ocurridos a mediados del siglo XIX en EspaĂąa en general y en Castilla la Vieja en particular, contando tambiĂŠn los antecedentes a esta situaciĂłn y sus causas. La tercera parte final cuenta las consecuencias de estas revueltas y la situaciĂłn posterior a ellas.Grado en AdministraciĂłn y DirecciĂłn de Empresa
Portal web para una PYME
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Special issue on evapotranspiration measurement and modeling
Water availability for irrigation throughout the world has been reduced in recent years due to a combination of frequent droughts and competition for water resources among agricultural, industrial, and urban users. In addition, some major agricultural areas face moderate to significant reductions of rainfall, or changes in timing of stream flow due to changes in timing of snowmelt, as a result of global climate change. Under such conditions, sophisticated irrigation water management will be required to optimize water use efficiency and maintain sufficient levels of crop productivity and quality. A key factor to achieve these targets is the estimation of actual evapotranspiration (ET). Accurate determination of ET can be a viable tool in better utilization of water resources through well-designed irrigation management programs. Reliable estimates of ET are also vital to develop criteria for in-season irrigation management, water resource allocation, long-term estimates of water supply, demand and use, design and management of water resources infrastructure, and evaluation of the effect of land use and management changes on the water balance
Special issue on evapotranspiration measurement and modeling
Water availability for irrigation throughout the world has been reduced in recent years due to a combination of frequent droughts and competition for water resources among agricultural, industrial, and urban users. In addition, some major agricultural areas face moderate to significant reductions of rainfall, or changes in timing of stream flow due to changes in timing of snowmelt, as a result of global climate change. Under such conditions, sophisticated irrigation water management will be required to optimize water use efficiency and maintain sufficient levels of crop productivity and quality. A key factor to achieve these targets is the estimation of actual evapotranspiration (ET). Accurate determination of ET can be a viable tool in better utilization of water resources through well-designed irrigation management programs. Reliable estimates of ET are also vital to develop criteria for in-season irrigation management, water resource allocation, long-term estimates of water supply, demand and use, design and management of water resources infrastructure, and evaluation of the effect of land use and management changes on the water balance
Assessing the sensitivity of inflation to economic activity
A number of academic studies suggest that from the mid-1990s onwards there were changes in the link between inflation and economic activity. However, it remains unclear the extent to which this phenomenon can be ascribed to a change in the structural relationship between inflation and output, as opposed to a change in the size and nature of the shocks hitting the economy. This paper uses a suite of models, such as time-varying VAR techniques, traditional macro models, as well as DSGE models, to investigate, for various European countries as well as for the euro area, the evolution of the link between inflation and resource utilization and its dependence on the nature and size of the shocks. Our analysis suggests that the relationship between inflation and activity has indeed been changing over time, while remaining positive, with the correlation peaking during recessions. Quantitatively, the link between output and inflation is found to be highly dependent on which type of shocks hit the economy: while, in general, all demand shocks to output imply a reaction of inflation of the same sign, the latter will be less pronounced when output fluctuations are driven by supply shocks. In addition, a sharp deceleration of activity, as opposed to a subdued but protracted slowdown, results in a swifter decline in inflation. Inflation exhibits a rather strong persistence, with a negative impact still visible three years after the initial shock. JEL Classification: E31, E32, E37demand shock, inflation response, Macro model, output growth, Phillips curve
Desarrollo de Ăndices fisiolĂłgicos para determinar el Ăłptimo EstrĂŠs HĂdrico en Olivo cv. Arbequina
37 p.Un estudio fue realizado en un huerto de olivos (Olea europaea L. cv Arbequina) para establecer relaciones entre los potenciales hĂdricos de antes del amanecer (Ψpd), de xilema (Ψx) y de hoja al medio dĂa (Ψmd) con la tasa fotosintĂŠtica (A), conductancia estomĂĄtica (gs) y transpiraciĂłn (E). El ensayo, ubicado en el valle Pencahue (RegiĂłn del Maule, Chile), fue realizado sobre ĂĄrboles de 7 aĂąos de edad, conducidos en monocono y regados por gotero. El diseĂąo experimental fue completamente
al azar, con cuatro tratamientos basados en mediciones de Ψx: T1 = nulo-leve (â1,75 MPa);
T2 = leve-moderado (â3,5 MPa); T3 = moderado-severo (â4,8 MPa) y T4 = severo (â6,0
MPa). Los resultados indicaron que existieron correlaciones altamente significativas entre
Ψx vs Ψmd (r2 = 0,85), Ψx vs Ψpd (r2 = 0,90) y Ψmd vs Ψpd (r2 = 0,87). Ademås, en el
estudio se observa una alta correlaciĂłn no lineal entre Ψpd vs A (r2 = 0,82); Ψpd vs gs (r2 = 0,78); Ψpd vs E (r2 = 0,76); Ψx vs A (r2 = 0,78); Ψx vs gs (r2 = 0,80); Ψx vs E (r2 = 0,77); Ψmd vs A (r2 = 0,73); Ψmd vs gs (r2 = 0,67) y Ψmd vs E (r2 = 0,72). Es importante indicar que estas correlaciones no lineales presentaron una disminuciĂłn exponencial hasta los â3,0; â3,6 y â5,5 MPa de Ψpd, Ψx y Ψmd, respectivamente, para luego decrecer en forma lineal. Los resultados de este estudio sugirieron que los umbrales fisiolĂłgicos para determinar la Ăłptima frecuencia de riego en olivo pueden ser â1,3, â2,1 y â3,6 MPa para Ψpd, Ψx y Ψmd,
respectivamente. Palabras claves: Olea europaea, Estado hĂdrico, Potencial hĂdrico de hoja antes del amanecer, Potencial hĂdrico de xilema, Potencial hĂdrico de hoja al mediodĂa, Tasa fotosintĂŠtica, Conductancia estomĂĄtica, TranspiraciĂł
Estimation of vineyard water requirements using satellite-based surface energy balance
115 p.Since the 90's as a consequence of the Global Warming and the âLa NiĂąaâ (ENSO) phenomena, the Chilean wine industry has been forced to increase irrigation systems investments, adopting new strategies of irrigation
scheduling to improve the vineyard water use efficiency without affecting the grapes yield and quality. To develop an adequate irrigation strategy, the first step has been to estimate the vineyard water uptake or actual evapotranspiration ETa).Traditionally, vineyard ETa has been estimated by multiplying the reference evapotranspiration (ETo) by a single crop coefficient (Kc). Unfortunately, a major uncertainty in this approach is that many Kc values reported in literature are empirically determined from point-based measurements, and they are unable to describe the spatial variability of vineyard Kc, for each phenological stage. Recent advancements in using satellite remote sensing to determine ETa over space and time have made it possible to assess the variation in crop ETa at low-cost. One of the most cited remote sensing-based algorithms is
METRIC (Mapping EvapoTranspiration at high Resolution with Internalized Calibration) which is a onedimensional surface energy based residual model that has been extensively customized for application in full covered crops. For sparse crops such vineyards, as far as we know the application of METRIC to estimate ETa and Kc is still unexplored. In this way, this thesis was developed with the aim of critically study the applicability of METRIC over a
drip-irrigated Merlot vineyard. To meet this, a study was carried out during the 2006-2007, 2007-2008 and 2008-2009 growing seasons. METRIC-based estimations were compared against ground measurements of vegetation indexes, surface energy balance components and vineyard ETa. Results indicated that METRICâs semi-empirical sub-models for estimate vegetation indexes should be calibrated before its direct application to
vineyards (Chapter 2). On the other hand, in the evaluation of METRIC to estimate the different components of the vineyard surface energy balance, results indicated that the compensation between the instantaneous
fluxes of net radiation, soil heat fluxes and latent heath fluxes produced acceptable estimations of latent heat luxes (error less than 10%) to extrapolate them to daily (24 h) evapotranspiration (ETa) (Chapter 3). Finally
for the main phenological stages of the Merlot vineyard, METRIC overestimated the Kc by about 10% in relation to ground measurements. However, those errors did not significantly affect the overall performance
of METRIC during the study period into the estimation of daily (24 h) ETa and Kc (Chapter 4). Results exposed from Chapters two to four suggest that it is possible to confirm that the METRIC model can be used
for obtain relatively good estimations of the vineyard ETa during the complete growing season
Diels-Alder cycloadditions in water for the straightforward preparation of peptideâoligonucleotide conjugates
The Diels-Alder reaction between diene-modified oligonucleotides and maleimide-derivatized peptides afforded peptideâoligonucleotide conjugates with high purity and yield. Synthesis of the reagents was easily accomplished by on-column derivatization of the corresponding peptides and oligonucleotides. The cycloaddition reaction was carried out in mild conditions, in aqueous solution at 37°C. The speed of the reaction was found to vary depending on the size of the reagents, but it can be completed in 8â10 h by reacting the diene-oligonucleotide with a small excess of maleimide-peptide
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