2,775 research outputs found
Transporte de fósforo en un Ultisol bajo pastura
Broadcast applications of inorganic fertilizer and organic amendments to pastures can contribute significant phosphorus (P) loads to surface waters. An experiment was conducted to quantify edge of field P concentrations in runoff and mass losses from plots in an Ultisol-Oxisol complex amended with two inorganic P levels [44 kg P/ha/yr (44PI) and 131 kg P/ha/yr (131 PI)], and an organic P source (broiler litter) [131 kg P/ha/yr (131 PC-)]. The total amount of P was split in two applications for the organic treatment and in four for the inorganic treatments. Vegetation within plots was mainly naturalized tropical pastures (80% coverage) and the soil slope was between 10 and 12%. Hydrologic discharge, suspended sediments, dissolved P and total P (TP) were quantified over a one-year period to 7 August 2003. Runoff from each field was diverted to a fractionator, where 1 or 10% was collected. Of the 174 precipitation events, 59 resulted in significant runoff, and hydrologic discharge accounted for 22% to 35% of the total rainfall (164.3 cm). Sediment losses ranged from 230 to 818 kg/ha. Cumulative TP mass losses were 3.19, 7.04, and 5.02 kg P/ha, for the 44PI, 131 PI, and 131PO treatments, respectively. These losses corresponded to 7.3, 4.9, and 3.5% of the annual P applied in the treatments 44PI, 131 PI, and 131PO, respectively. Although the magnitude of P losses was relatively low from an agricultural production standpoint, these can impact surface-water quality via nutrient enrichment. The greatest magnitude of TP mass losses occurred when application coincided with frequent intense rainfall events. RESUMEN Las aplicaciones de fertilizantes y enmiendas orgánicas a los suelos pueden contribuir cantidades significativas de fósforo (P) a las aguas superficiales. Se realizó un experimento para cuantificar las concentraciones de P en la escorrentía y las pérdidas en masa de P al borde de predio en un Ultisol enmendado con dos niveles de superfosfato triple como fuente inorgánica de P [44 kg P/ha/año (44 Pl) y 131 kg P/ha/año (131PI)] y una fuente orgánica de P [131 kg P/ha/año (131PO)] aplicado como pollinaza. La aplicación de P se fraccionó en dos para la fuente orgánica y en cuatro para la fuente inorgánica. La vegetación dentro de los predios era principalmente de pasturas tropicales naturalizadas y la pendiente varió entre 10 y 12%. La descarga hidrológica, sedimentos suspendidos, P disuelto y P total se cuantificaron durante un año. La escorrentía de cada parcela se canalizó hacia un fraccionador donde se recolectó el 1% o el 10% de la misma. De los 174 eventos de precipitación, 59 resultaron en escorrentía significativa, y la descarga hidrológica varió entre 22 y 35% de la totalidad (164.3 cm). Las pérdidas de sedimento variaron entre 230 y 818 kg/ha/año. Las pérdidas de P cumulativas fueron 3.19, 7.04, y 5.02 kg P/ha, para los tratamientos 44PI, 131 PI, y 131PO, respectivamente. Desde una perspectiva de producción agrícola, la magnitud de las pérdidas de P fueron bajas, pero estas cantidades pueden afectar las aguas superficiales vía el enriquecimiento nutricional. Las mayores pérdidas de P ocurrieron en periodos de tiempo cuando la aplicación coincidió con eventos de lluvia de relativamente alta intensidad y frecuencia. Las aplicaciones de fertilizantes y enmiendas orgánicas a los suelos pueden contribuir cantidades significativas de fósforo (P) a las aguas superficiales. Se realizó un experimento para cuantificar las concentraciones de P en la escorrentía y las pérdidas en masa de P al borde de predio en un Ultisol enmendado con dos niveles de superfosfato triple como fuente inorgánica de P [44 kg P/ha/año (44 Pl) y 131 kg P/ha/año (131PI)] y una fuente orgánica de P [131 kg P/ha/año (131PO)] aplicado como pollinaza. La aplicación de P se fraccionó en dos para la fuente orgánica y en cuatro para la fuente inorgánica. La vegetación dentro de los predios era principalmente de pasturas tropicales naturalizadas y la pendiente varió entre 10 y 12%. La descarga hidrológica, sedimentos suspendidos, P disuelto y P total se cuantificaron durante un año. La escorrentía de cada parcela se canalizó hacia un fraccionador donde se recolectó el 1% o el 10% de la misma. De los 174 eventos de precipitación, 59 resultaron en escorrentía significativa, y la descarga hidrológica varió entre 22 y 35% de la totalidad (164.3 cm). Las pérdidas de sedimento variaron entre 230 y 818 kg/ha/año. Las pérdidas de P cumulativas fueron 3.19, 7.04, y 5.02 kg P/ha, para los tratamientos 44PI, 131 PI, y 131PO, respectivamente. Desde una perspectiva de producción agrícola, la magnitud de las pérdidas de P fueron bajas, pero estas cantidades pueden afectar las aguas superficiales vía el enriquecimiento nutricional. Las mayores pérdidas de P ocurrieron en periodos de tiempo cuando la aplicación coincidió con eventos de lluvia de relativamente alta intensidad y frecuencia
Neural networks are a priori biased towards Boolean functions with low entropy
Understanding the inductive bias of neural networks is critical to explaining
their ability to generalise. Here, for one of the simplest neural networks -- a
single-layer perceptron with n input neurons, one output neuron, and no
threshold bias term -- we prove that upon random initialisation of weights, the
a priori probability P(t) that it represents a Boolean function that classifies
t points in {0,1}^n as 1 has a remarkably simple form: P(t) = 2^{-n} for 0\leq
t < 2^n.
Since a perceptron can express far fewer Boolean functions with small or
large values of t (low entropy) than with intermediate values of t (high
entropy) there is, on average, a strong intrinsic a-priori bias towards
individual functions with low entropy. Furthermore, within a class of functions
with fixed t, we often observe a further intrinsic bias towards functions of
lower complexity. Finally, we prove that, regardless of the distribution of
inputs, the bias towards low entropy becomes monotonically stronger upon adding
ReLU layers, and empirically show that increasing the variance of the bias term
has a similar effect
Multicentre, randomised, single-blind, parallel group trial to compare the effectiveness of a Holter for Parkinson's symptoms against other clinical monitoring methods: Study protocol
Introduction In recent years, multiple studies have aimed to develop and validate portable technological devices capable of monitoring the motor complications of Parkinson's disease patients (Parkinson's Holter). The effectiveness of these monitoring devices for improving clinical control is not known. Methods and analysis This is a single-blind, clusterrandomised controlled clinical trial. Neurologists from Spanish health centres will be randomly assigned to one of three study arms (1:1:1): (a) therapeutic adjustment using information from a Parkinson's Holter that will be worn by their patients for 7 days, (b) therapeutic adjustment using information from a diary of motor fluctuations that will be completed by their patients for 7 days and (c) therapeutic adjustment using clinical information collected during consultation. It is expected that 162 consecutive patients will be included over a period of 6 months. The primary outcome is the efficiency of the Parkinson's Holter compared with traditional clinical practice in terms of Off time reduction with respect to the baseline (recorded through a diary of motor fluctuations, which will be completed by all patients). As secondary outcomes, changes in variables related to other motor complications (dyskinesia and freezing of gait), quality of life, autonomy in activities of daily living, adherence to the monitoring system and number of doctor-patient contacts will be analysed. The noninferiority of the Parkinson's Holter against the diary of motor fluctuations in terms of Off time reduction will be studied as the exploratory objective. Ethics and dissemination approval for this study has been obtained from the Hospital Universitari de Bellvitge Ethics Committee. The results of this study will inform the practical utility of the objective information provided by a Parkinson's Holter and, therefore, the convenience of adopting this technology in clinical practice and in future clinical trials. We expect public dissemination of the results in 202
Solving the time capacitated arc routing problem under fuzzy and stochastic travel and service times
Stochastic, as well as fuzzy uncertainty, can be found in most real-world systems. Considering both types of uncertainties simultaneously makes optimization problems incredibly challenging. In this paper we propose a fuzzy simheuristic to solve the Time Capacitated Arc Routing Problem (TCARP) when the nature of the travel time can either be deterministic, stochastic or fuzzy. The main goal is to find a solution (vehicle routes) that minimizes the total time spent in servicing the required arcs. However, due to uncertainty, other characteristics of the solution are also considered. In particular, we illustrate how reliability concepts can enrich the probabilistic information given to decision-makers. In order to solve the aforementioned optimization problem, we extend the concept of simheuristic framework so it can also include fuzzy elements. Hence, both stochastic and fuzzy uncertainty are simultaneously incorporated into the CARP. In order to test our approach, classical CARP instances have been adapted and extended so that customers' demands become either stochastic or fuzzy. The experimental results show the effectiveness of the proposed approach when compared with more traditional ones. In particular, our fuzzy simheuristic is capable of generating new best-known solutions for the stochastic versions of some instances belonging to the tegl, tcarp, val, and rural benchmarks.This work has been partially supported by the Spanish Ministry of Science (PID2019-111100RB-C21/AEI/10.13039/01100011033), as well as by the Barcelona Council and the “laCaixa” Foundation under the framework of the Barcelona Science Plan 2020-2023 (grant21S09355-01) and Generalitat Valenciana (PROMETEO/2021/065).Peer ReviewedPostprint (published version
Synthesis and Structural Analysis of Push-Pull Imidazole-Triazole Based Fluorescent Bifunctional Chemosensor for CU2+ and FE2+ Detection
[Abstract] Fluorescent imidazole-triazole based ligands L1 and L2 have been designed as chemical push-pull chemosensors for divalent metal ions and synthesized through palladium-catalyzed cross-coupling reactions using indium organometallics and click chemistry. The novel ligands exhibit intense absorption in the ultraviolet region with high molar extinction coefficients, and strong fluorescence emission with large Stokes displacements. On the basis of UV–Vis absorption spectroscopy and fluorescence emission data in acetonitrile, L1 is shown as a bifuncional chemosensor with differential response for Fe2+ and Cu2+ over a range of selected 3d divalent and other metal ions. The binding site of the ligand was established by single-crystal X-ray diffraction and 1H NMR spectroscopy studies. The association constants, determined by spectrofluorimetric titrations, show a steady binding affinity of L1 for Cu2+ and Fe2+ in comparison with other previously reported fluorescent bidentate chemosensors, offering the lowest limit of detection (LOD) with Cu2+. DFT calculations provide a rationale properly understanding and interpreting the experimentally observed results. Indeed, a mechanism of the different optical responses of L1 towards 3d divalent metal ions is proposed.We thank the Spanish Ministerio de Ciencia, Innovación y Universidades (PGC2018-097792-B-I00), Xunta de Galicia (GRC2018/039 and ED431B 2020/52) and EDRF funds for financial and human support. ADL thanks the Xunta de Galicia for a predoctoral fellowship (EDA 481A-2020/017). LV thanks CACTI for X-ray measurementsXunta de Galicia; GRC2018/039Xunta de Galicia; ED431B 2020/52Xunta de Galicia; ED 481A-2020/01
Tunable dual-band filters based on capacitive-loaded stepped-impedance resonators
This paper proposes the design of tunable dual-band
filters for multi-band multi-standard systems. The main
objective is to provide frequency tunability in the second band
while maintaining the first band fixed. To this end, the
capacitive-loaded stepped-impedance resonator is used. The
work is divided into two main parts. In the first part, a deep
analysis of the capacitive-loaded stepped-impedance resonator
structure is done, which provides analytical closed-form design
equations which eases their design in front of the several
approaches available in the literature up to now. The analysis is
also particularized for the case of the capacitive-loaded uniform
resonator. In the second part, resonators are integrated in two
dual-band tunable filters.Postprint (published version
Improving Catalyst Activity in Hydrocarbon Functionalization by Remote Pyrene–Graphene Stacking
A copper complex bearing an N‐heterocyclic carbene ligand with a pyrene “tail” attached to the backbone has been prepared and supported on reduced graphene oxide (rGO). The free and supported copper materials have been employed as homogeneous and heterogeneous catalysts in the functionalization of hydrocarbons such as n‐hexane, cyclohexane, and benzene through incorporation of the CHCO2Et unit from ethyl diazoacetate. The graphene‐anchored complex displays higher reaction rates and induces higher yields than its soluble counterpart, features that can be rationalized in terms of a decrease in electron density at the metal center due to a remote net electronic flux from the supported copper complex to the graphene surface.The authors would like to thank the financial support of the
MINECO (CTQ2017-82893-C2-1-R and CTQ2015-69153-C2-2-
R), Junta de Andalucía (P12-FQM-1765) and Universitat Jaume I
(UJI-B2018-23). D. V-E thanks the MINECO for a grant
(FPU15/03011). The authors thank the ‘Servei Central
d’Instrumentació Científica (SCIC)’ of the Universitat Jaume I
Linear Strain Tensors on Hyperbolic Surfaces and Asymptotic Theories for Thin Shells
We perform a detailed analysis of the solvability of linear strain equations
on hyperbolic surfaces. We prove that if the surface is a smooth
noncharacteristic region, any first order infinitesimal isometry can be matched
to an infinitesimal isometry of an arbitrarily high order. The implications of
this result for the elasticity of thin hyperbolic shells are discussed
An oleuropein β-glucosidase from olive fruit is involved in determining the phenolic composition of virgin olive oil
Phenolic composition of virgin olive oil is determined by the enzymatic and/or chemical reactions that take place during olive fruit processing. Of these enzymes, β-glucosidase activity plays a relevant role in the transformation of the phenolic glycosides present in the olive fruit, generating different secoiridoid derivatives. The main goal of the present study was to characterize olive fruit β-glucosidase genes and enzymes responsible for the phenolic composition of virgin olive oil. To achieve that, we have isolated an olive β-glucosidase gene from cultivar Picual (OepGLU), expressed in Nicotiana benthamiana leaves and purified its corresponding recombinant enzyme. Western blot analysis showed that recombinant OepGLU protein is detected by an antibody raised against the purified native olive mesocarp β-glucosidase enzyme, and exhibits a deduced molecular mass of 65.0 kDa. The recombinant OepGLU enzyme showed activity on the major olive phenolic glycosides, with the highest levels with respect to oleuropein, followed by ligstroside and demethyloleuropein. In addition, expression analysis showed that olive GLU transcript level in olive fruit is spatially and temporally regulated in a cultivar-dependent manner. Furthermore, temperature, light and water regime regulate olive GLU gene expression in olive fruit mesocarp. All these data are consistent with the involvement of OepGLU enzyme in the formation of the major phenolic compounds present in virgin olive oil
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