Shape Persistence in Elicited Subjective Crop Yield Probability Density Functions

The shape persistence of a crop yield probability density function (PDF) was studied by using two variants of the Visual Impact Method (VIM) to elicit subjective estimations by farmers. In one variant ten weights were used to describe the PDF and in the other variant the farmer chose the number of weights. Results were compared directly and by means of Weibull distributions fitting, with evidence being obtained in favor of methodological persistence and the equivalence of the two estimation methods.Subjective crop yield PDF elicitation, Visual impact method, Methodological persistence, Crop Production/Industries,

Elicitation of Subjective Crop Yield PDF for DSS Implementation

The aim of this research is to establish the persistence of annual crop yield point values subjective estimates, and the coherence and reliability of subjective crop yield probability density functions (PDF) elicited from a series of interviews carried out on a wide group of farmers, and then to determine whether they should be included or not in a decision support system (DSS). Three different elicitation techniques were used: a) The Two Step PDF estimation method b) Triangular distribution c) Beta distribution Although the results are noteworthy, further studies should be carried out to perfect the aforementioned techniques before crop yield PDF's are used in decision making processes.decision support systems, subjective crop yield PDF elicitation, two step PDF estimation method, triangular and beta distributions, Crop Production/Industries,

The origin of the LMC stellar bar: clues from the SFH of the bar and inner disk

We discuss the origin of the LMC stellar bar by comparing the star formation histories (SFH) obtained from deep color-magnitude diagrams (CMDs) in the bar and in a number of fields in different directions within the inner disk. The CMDs, reaching the oldest main sequence turnoffs in these very crowded fields, have been obtained with VIMOS on the VLT in service mode, under very good seeing conditions. We show that the SFHs of all fields share the same patterns, with consistent variations of the star formation rate as a function of time in all of them. We therefore conclude that no specific event of star formation can be identified with the formation of the LMC bar, which instead likely formed from a redistribution of disk material that occurred when the LMC disk became bar unstable, and shared a common SFH with the inner disk thereafter. The strong similarity between the SFH of the center and edge of the bar rules out significant spatial variations of the SFH across the bar, which are predicted by scenarios of classic bar formation through buckling mechanisms.Comment: MNRAS Letters, accepte

Catalan university libraries

A university library is a cornerstone in the research of any country, and as the English say, it is the heart and measure of a university.Before we embark upon the study of Catalan university libraries it would be convenient to have an overview of the university features which will contribute to our understanding the fundamental traits of the universities that they rely upon.The Universitat de Barcelona (UB) was founded in the 15th century and was the only Catalan University until the 20th century. It has the largest number ofstudents and centres of all the Catalan Universities.The Universitat Autónoma de Barcelona (UAB) was founded in 1968 and is located in Bellaterra, in the municipality of Cerdanyola. It is the only Catalan university with an out-of-town campus.The Universitat Politécnica de Catalunya (UPC) was founded in 1971 and it brought together the various technical colleges and universities that already existed in Barcelona and other Catalan towns, some of which were over a century old. This university is solely devoted to technical studies.The Universitat Pompeu Fabra (UPF) was founded in 1990 in Barcelona. It specializes in social sciences and the humanities, and it has not yet developed its full potential.The Universitat Ramon Llull (URL) was officially recognized as the first private Catalan university in 1991. It amalgamates several private further education colleges which were run by religious institutions, such as the Institut Químic de Sarria and Escola Blanquerna

Spatially resolved LMC star formation history: I. Outside in evolution of the outer LMC disk

We study the evolution of three fields in the outer LMC disk Rgc=3.5-6.2 Kpc. Their star formation history indicates a stellar populations gradient such that younger stellar populations are more centrally concentrated. We identify two main star forming epochs, separated by a period of lower activity between ~7 and ~4 Gyr ago. Their relative importance varies from a similar amount of stars formed in the two epochs in the innermost field, to only 40% of the stars formed in the more recent epoch in the outermost field. The young star forming epoch continues to the present time in the innermost field, but lasted only till ~0.8 and 1.3 Gyr ago at Rgc=5.5 degrees and 7.1 degrees, respectively. This gradient is correlated with the measured HI column density and implies an outside-in quenching of the star formation, possibly related to a variation of the size of the HI disk. This could either result from gas depletion due to star formation or ram-pressure stripping, or from to the compression of the gas disk as ram-pressure from the Milky Way halo acted on the LMC interstellar medium. The latter two situations may have occurred when the LMC first approached the Milky Way.Comment: 15 pages, 13 figures, 4 tables. MNRAS, in pres

Modelos de erosión de base física: características y utilidades

[Resumen] El desarrollo de los modelos de erosión tiene como objetivo facilitar la predicción de la erosión y diseñar así, las posibles medidas de prevención para evitar la pérdida de suelo. Actualmente, estos modelos de erosión tienden a describir los procesos mediante aproximaciones de tipo físico, y han aumentado su complejidad en el tratamiento de datos. En el presente trabajo se analizan las diferencias y semejanzas de 5 modelos principales de erosión de los últimos 20 años (ANSWERS, CREAMS, KINEROS, EUROSEM y WEPP), y se plantean los posibles errores que involucran estos modelos "avanzados", ya sea por su complejidad, como por su utilización.[Abstract] At present, erosion models are common too1s to cope with erosive processes. These models are aimed to predict erosion, thus helping to design management actions oriented to prevent soil loss. Nowadays, erosion models represent physica1 processes, and their comp1exity increas. Diferences and resemblances between 5 main erosion models developed in the 1ast 20 years (ANSWERS, CREAMS, KINEROS, EUROSEM and WEPP), and it's questioned the possible errors associated with these "advanced" models are discussed

Properties of RR Lyrae stars in the inner regions of the Large Magellanic Cloud. II. The extended sample

All galaxies that have been adequately examined so far have shown an extended stellar halo. To search for such a halo in the LMC we have obtained low-resolution spectra for 100 LMC RR Lyrae stars, of which 87 are in the field and 13 in the clusters NGC1835 and NGC2019. We measured radial velocities for 87 LMC RR Lyrae stars, and metallicities for 78 RR Lyrae stars, nearly tripling the previous sample. These targets are located in 10 fields covering a wide range of distances, out to 2.5 degrees from the center of the LMC. Our main result is that the mean velocity dispersion for the LMC RR Lyrae stars is 50+-2km/s. This quantity does not appear to vary with distance from the LMC center. The metallicity shows a Gaussian distribution, with mean [Fe/H]=-1.53+-0.02dex, and dispersion 0.20 dex in the Harris metallicity scale, confirming that they represent a very homogeneous metal-poor population. There is no dependence between the kinematics and metallicity of the field RR Lyrae star population. Using good quality low-resolution spectra from FORS1, FORS2 and GEMINI-GMOS we have found that field RR Lyrae stars in the LMC show a large velocity dispersion and that this indicate the presence of old and metal-poor stellar halo. All the evidence so far for the halo, however, is from the spectroscopy of the inner LMC regions, similar to the inner flattened halo in our Galaxy. Further study is necessary to confirm this important result.Comment: 12 pages, 4 figure

Developing a novel approach to analyse the regimes of temporary streams and their controls on aquatic biota

Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. The use of the aquatic fauna structural and functional characteristics to assess the ecological quality of a temporary stream reach can not therefore be made without taking into account the controls imposed by the hydrological regime. This paper develops some methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: flood, riffles, connected, pools, dry and arid. We used the water discharge records from gauging stations or simulations using rainfall-runoff models to infer the temporal patterns of occurrence of these states using the developed aquatic states frequency graph. The visual analysis of this graph is complemented by the development of two metrics based on the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of the aquatic regimes of temporary streams in terms of their influence over the development of aquatic life is put forward, defining Permanent, Temporary-pools, Temporary-dry and Episodic regime types. All these methods were tested with data from eight temporary streams around the Mediterranean from MIRAGE project and its application was a precondition to assess the ecological quality of these streams using the current methods prescribed in the European Water Framework Directive for macroinvertebrate communities