640 research outputs found
Desarrollo de un algoritmo de solución directa para el cálculo de distribuciones óptimas de cultivos bajo riego deficitario controlado
La adecuada gestión de un recurso natural cada vez más escaso, como es el agua, implica
maximizar la eficiencia en su uso. Desde el punto de vista de una explotación agraria, es de
la máxima importancia encontrar la distribución óptima de cultivos que maximice el margen
bruto obtenido con el agua de riego disponible. Actualmente, los métodos de optimización
disponibles para resolver este problema no lineal, recurren a métodos de optimización
heurísticos de propósito general mucho más lentos y menos eficientes de lo que sería un
algoritmo de optimización de solución directa, donde se conocen los mecanismos
involucrados y las sinergias existentes entre los cultivos para la obtención de la solución
óptima del problema. El objetivo del presente trabajo es desarrollar un algoritmo de solución
directa capaz de determinar la distribución óptima de cultivos que sea compatible con el
modelo MOPECO (Modelo de Optimización Económica del agua de riego). La solución
óptima se consigue con sólo uno o dos cultivos, pero esta solución no es la más adecuada
desde el punto de vista agronómico (p.e. rotación de cultivos, PAC, etc.), por lo que ha sido
necesario adaptar el algoritmo desarrollado para manejar este tipo de situaciones. Para una
hipotética explotación de 100 ha, considerando 10 cultivos diferentes y 11 escenarios de
volumen de agua total disponible, se han comparado los resultados del algoritmo
desarrollado con las soluciones ofrecidas por el software de optimización LINGO y los
algoritmos genéticos. El algoritmo desarrollado consigue márgenes brutos un 0,5% inferiores
a los de LINGO, y un 1,1% mayores que los algoritmos genéticos, reduciendo el tiempo de
cálculo entre 50-100 y 2000 veces, respectivamente
Hydrolysable Tannins and Biological Activities of Meriania hernandoi and Meriania nobilis (Melastomataceae)
A bio-guided study of leaf extracts allowed the isolation of two new macrobicyclic
hydrolysable tannins, namely merianin A (1) and merianin B (2), and oct-1-en-3-yl
b-xylopyranosyl-(1”-6’)-b-glucopyranoside (3) from Meriania hernandoi, in addition to 11 known
compounds reported for the first time in the Meriania genus. The structures were elucidated by
spectroscopic analyses including one- and two-dimensional NMR techniques and mass spectrometry.
The bioactivities of the compounds were determined by measuring the DPPH radical scavenging
activity and by carrying out antioxidant power assays (FRAP), etiolated wheat coleoptile assays
and phytotoxicity assays on the standard target species Lycopersicum esculentum W. (tomato).
Compounds 1 and 2 exhibited the best free radical scavenging activities, with FRS50 values of
2.0 and 1.9 M, respectively
Revista de Vertebrados de la Estación Biológica de Doñana
Captura de Petromyzon marinus lo en las Marismas del GuadalquivirEstudio sobre la Lagartiia de Valverde Algyroides marchi (Reptilia, Lacertidae)Dimorfismo sexual en Psammodromuus algirus (Reptilia, Lacertidae)Mecanismos de parasitización por Clamator glandarius y defensa por Pica pica.Nidificación de Cyanopica cyana en Doñana.Reproducción de la Urraca (P.pica) en DoñanaNesting relationship between Columba palambus and Milvus migransBiometría y dimorfismo sexual en el Calamón (Polphyrio porphyrio).Sobre sexo, mecanismos y proceso de reproducciónen el Buitre Leonado (Gyps fulvus)Aves anilladas por la Estación Biológica de Doñana. Informe Nº 1. (Años 1964 a 1971)Dimorfismo sexual y diferenciación de edades en Sturnus unicolor Temm.Contribución al estudio de la biología y ecología del Lirón Careto, Eliomys quercinus Linnaeus 1766, en Iberia Central, Parte 1: Crecimiento, Reproducción y Nidificación.Sobre el Lobo (Canis lupus) ibérico:1. Dimorfismo sexual en cráneosMorfología y dimorfismo sexual de la pelvis de Pitymys duodecimcostatusAlgunos aspectos del diformismo sexual en el cráneo de las Ginetas españolas, (Genetta genetta) (L.) 1758Peer reviewe
Evolutionary relationships among barley and <i>Arabidopsis</i> core circadian clock and clock-associated genes
The circadian clock regulates a multitude of plant developmental and metabolic processes. In crop species, it contributes significantly to plant performance and productivity and to the adaptation and geographical range over which crops can be grown. To understand the clock in barley and how it relates to the components in the Arabidopsis thaliana clock, we have performed a systematic analysis of core circadian clock and clock-associated genes in barley, Arabidopsis and another eight species including tomato, potato, a range of monocotyledonous species and the moss, Physcomitrella patens. We have identified orthologues and paralogues of Arabidopsis genes which are conserved in all species, monocot/dicot differences, species-specific differences and variation in gene copy number (e.g. gene duplications among the various species). We propose that the common ancestor of barley and Arabidopsis had two-thirds of the key clock components identified in Arabidopsis prior to the separation of the monocot/dicot groups. After this separation, multiple independent gene duplication events took place in both monocot and dicot ancestors. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00239-015-9665-0) contains supplementary material, which is available to authorized users
Assessing the congruence of thermal niche estimations derived from distribution and physiological data. A test using diving beetles.
A basic aim of ecology is to understand the determinants of organismal distribution, the niche concept and species distribution models providing key frameworks to approach the problem. As temperature is one of the most important factors affecting species distribution, the estimation of thermal limits is crucially important for inferring range constraints. It is expectable that thermal physiology data derived from laboratory experiments and species' occurrences may express different aspects of the species' niche. However, there is no study systematically testing this prediction in a given taxonomic group while controlling by potential phylogenetic inertia. We estimate the thermal niches of twelve Palaearctic diving beetles species using physiological data derived from experimental analyses in order to examine the extent to which these coincided with those estimated from distribution models based on observed occurrences. We found that thermal niche estimates derived from both approaches lack general congruence, and these results were similar before and after controlling by phylogeny. The congruence between potential distributions obtained from the two different procedures was also explored, and we found again that the percentage of agreement were not very high (~60%). We confirm that both thermal niche estimates derived from geographical and physiological data are likely to misrepresent the true range of climatic variation that these diving beetles are able to tolerate, and so these procedures could be considered as incomplete but complementary estimations of an inaccessible reality
Auditory-inspired morphological processing of speech spectrograms: applications in automatic speech recognition and speech enhancement
New auditory-inspired speech processing methods are presented in this paper, combining spectral subtraction and two-dimensional non-linear filtering techniques originally conceived for image processing purposes. In particular, mathematical morphology operations, like erosion and dilation, are applied to noisy speech spectrograms using specifically designed structuring elements inspired in the masking properties of the human auditory system. This is effectively complemented with a pre-processing stage including the conventional spectral subtraction procedure and auditory filterbanks. These methods were tested in both speech enhancement and automatic speech recognition tasks. For the first, time-frequency anisotropic structuring elements over grey-scale spectrograms were found to provide a better perceptual quality than isotropic ones, revealing themselves as more appropriate—under a number of perceptual quality estimation measures and several signal-to-noise ratios on the Aurora database—for retaining the structure of speech while removing background noise. For the second, the combination of Spectral Subtraction and auditory-inspired Morphological Filtering was found to improve recognition rates in a noise-contaminated version of the Isolet database.This work has been partially supported by the Spanish Ministry of Science and Innovation CICYT Project No. TEC2008-06382/TEC.Publicad
Acceptability and feasibility of a virtual community of practice to primary care professionals regarding patient empowerment: A qualitative pilot study
Background: Virtual communities of practice (vCoPs) facilitate online learning via the exchange of experiences and knowledge between interested participants. Compared to other communities, vCoPs need to overcome technological structures and specific barriers. Our objective was to pilot the acceptability and feasibility of a vCoP aimed at improving the attitudes of primary care professionals to the empowerment of patients with chronic conditions. Methods: We used a qualitative approach based on 2 focus groups: one composed of 6 general practitioners and the other of 6 practice nurses. Discussion guidelines on the topics to be investigated were provided to the moderator. Sessions were audio-recorded and transcribed verbatim. Thematic analysis was performed using the ATLAS-ti software. Results: The available operating systems and browsers and the lack of suitable spaces and time were reported as the main difficulties with the vCoP. The vCoP was perceived to be a flexible learning mode that provided up-to-date resources applicable to routine practice and offered a space for the exchange of experiences and approaches. Conclusions: The results from this pilot study show that the vCoP was considered useful for learning how to empower patients. However, while vCoPs have the potential to facilitate learning and as shown create professional awareness regarding patient empowerment, attention needs to be paid to technological and access issues and the time demands on professionals. We collected relevant inputs to improve the features, content and educational methods to be included in further vCoP implementation. Trial registration: ClinicalTrials.gov, NCT02757781. Registered on 25 April 2016.This study was financed by Instituto de Salud Carlos III and Cofinanced by Fondo
Europeo de Desarrollo Regional (FEDER). Ministerio de Economía
y Competitividad. Gobierno de España. (PI15/00164, PI15/00586, PI15/00566
Utilization of Cooked Cassava and Taro as Alternative Feed in Enhancing Pig Production in Ecuadorian Backyard System
Pork production in Ecuador is of significant economic and nutritional importance. Many of these operations are family- or backyard-based and utilize alternative feed ingredients to reduce production costs. The current study aimed to determine the chemical composition of cooked cassava and taro, and to evaluate their inclusion in the feed of backyard pigs during the growth and fattening phases. A total of 42 castrated pigs from two geographic locations in Ecuador were studied over a period of 100 days, during which their weight and measurements were recorded at three-week intervals. At the end of the experiment, ileum samples were collected from the slaughtered pigs in order to calculate the apparent digestibility of the feed. The crude protein levels of cassava and taro were found to be 3.2% and 2.1%, respectively. The combination of cooked cassava and taro was found to be a suitable replacement for corn, with the best results observed in the group receiving a diet incorporating 21% each of cassava and taro. Analysis of the ileal content also revealed that this group exhibited the highest nitrogen assimilation from the diet
The Calcium-Looping technology for CO2 capture: On the important roles of energy integration and sorbent behavior
The Calcium Looping (CaL) technology, based on the multicyclic carbonation/calcination of CaO in gas-solid fluidized bed reactors at high temperature, has emerged in the last years as a potentially low cost technology for CO2 capture. In this manuscript a critical review is made on the important roles of energy integration and sorbent behavior in the process efficiency. Firstly, the strategies proposed to reduce the energy demand by internal integration are discussed as well as process modifications aimed at optimizing the overall efficiency by means of external integration. The most important benefit of the high temperature CaL cycles is the possibility of using high temperature streams that could reduce significantly the energy penalty associated to CO2 capture. The application of the CaL technology in precombustion capture systems and energy integration, and the coupling of the CaL technology with other industrial processes are also described. In particular, the CaL technology has a significant potential to be a feasible CO2 capture system for cement plants. A precise knowledge of the multicyclic CO2 capture behavior of the sorbent at the CaL conditions to be expected in practice is of great relevance in order to predict a realistic capture efficiency and energy penalty from process simulations. The second part of this manuscript will be devoted to this issue. Particular emphasis is put on the behavior of natural limestone and dolomite, which would be the only practical choices for the technology to meet its main goal of reducing CO2 capture costs. Under CaL calcination conditions for CO2 capture (necessarily implying high CO2 concentration in the calciner), dolomite seems to be a better alternative to limestone as CaO precursor. The proposed techniques of recarbonation and thermal/mechanical pretreatments to reactivate the sorbent and accelerate calcination will be the final subjects of this review
Computational modelling of hydrogen assisted fracture in polycrystalline materials
We present a combined phase field and cohesive zone formulation for hydrogen
embrittlement that resolves the polycrystalline microstructure of metals.
Unlike previous studies, our deformation-diffusion-fracture modelling framework
accounts for hydrogen-microstructure interactions and explicitly captures the
interplay between bulk (transgranular) fracture and intergranular fracture,
with the latter being facilitated by hydrogen through mechanisms such as grain
boundary decohesion. We demonstrate the potential of the theoretical and
computational formulation presented by simulating inter- and trans-granular
cracking in relevant case studies. Firstly, verification calculations are
conducted to show how the framework predicts the expected qualitative trends.
Secondly, the model is used to simulate recent experiments on pure Ni and a
Ni-Cu superalloy that have attracted particular interest. We show that the
model is able to provide a good quantitative agreement with testing data and
yields a mechanistic rationale for the experimental observations
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