Investigació sobre spatial-division multiplexing (SDM) en comunicacions per fibra òptica

Investigación sobre spatial-division multiplexing (SDM) en comunicaciones por fibra ópticaIn this work we analyze propagating LP modes (Linearly Polarized) in different independent spatial paths, mentioning the energetic density of the electromagnetic fields of these modes with a fixed normalized frequency and the evolution during the normalized frequency’s increment too. Thus, we have implemented an analytic and visual study through MATLAB programming language.En este trabajo analizaremos los modos de propagación LP (Linearly Polarized) en distintos caminos espaciales independientes, atendiendo a la densidad energética de los campos electromagnéticos de dichos modos con una frecuencia normalizada fijada y también a su evolución a medida que ésta aumenta. Así, se ha llevado a cabo un estudio analítico y visual mediante el lenguaje de programación MATLAB.En aquest treball analitzarem els modes de propagació LP (Linearly Polarized) en diferents camins espacials independents, atenent a la densitat energètica dels camps electromagnètics d’aquests modes amb una freqüència normalitzada fixa i també a la seva evolució a mesura que aquesta augmenta. Així, s’ha dut a terme un estudi analític i visual mitjançant el llenguatge de programació MATLAB

Origin and role of neural signatures in bursting neurons

Copyright 2007 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.A traditional view in neuroscience is that information arriving through one channel, i.e. a synapse, is encoded through a single code in the signal, e.g., the rate or the precise timing of the incoming events. However, not all the neural readers have to be interested in the same aspect of a common input signal, especially in multifunctional networks that can take advantage of several simultaneous codes. Multiple codes can be used to discriminate or contextualize certain inputs, even in single neurons. Dynamical mechanisms can add to the existing hard-wired connectivity for this task. Recent experiments have revealed the existence of neural signatures in the activity of bursting cells of invertebrate central pattern generators. These signatures consist of cell-specific spike timings in the bursting activity of the neurons. The signatures coexist with the information encoded in the frequency and/or phase relationships of the slow waves. The functional role of these neural fingerprints is still unclear. Based on experiments and using conductance-based models, we discuss the origin and the role of neural signatures as a part of a multicoding strategy for single cells in different types of neural circuits.This work was supported by Fundacion BBVA, MEC BFU2006-07902/BFI and MEC TIN2004-04363-C03-03

Effect of individual spiking activity on rhythm generation of central pattern generators

This is the author’s version of a work that was accepted for publication in Neurocomputing. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Neurocomputing 58-60 (2004):10.1016/j.neucom.2004.01.091Central Pattern Generators (CPGs) are highly specialized neural networks often with redundant elements that allow the system to act properly in case of error. CPGs are multifunctional circuits, i.e. the same CPG can produce many di®erent rhythms in response to modulatory or sensory inputs. All these rhythms have to be optimal for motor control and coordination. In this paper, we use a model of the well-known pyloric CPG of crustacean to analyze the importance of redundant connections and individual spiking activity in the generation of the CPG rhythm. In particular, we study the e®ect of di®erent spike distributions of a neuron on the collective behavior of the CPG.This work was supported by the Spanish MCyT (BFI-2000- 0157 and TIC 2002-572-C02-02

Estimate of soil hydraulic properties from disc infiltrometer threedimensional infiltration curve: theoretical analysis and field applicability

9 Pags., 3 Figs., 2 Tabls. The definitive version is available at: http://www.sciencedirect.com/science/journal/18780296/19/supp/CThis paper describes a new method (NSQE) to estimate soil hydraulic properties (sorptivity, S, and hydraulic conductivity, K) from full-time cumulative infiltration curves. The technique relies on an inverse procedure involving the quasi-exact equation of Haverkamp et al. (1994). The numerical resolution is described and the sensitivity of the method is theoretically evaluated, showing that the accuracy of the estimates depends on the measured infiltration time. A new procedure to detect and remove the effect of the contact sand layer on the cumulative infiltration curve is also given. The method was subsequently compared to the differentiated linearization procedure (DL), which calculate K and S from the simplified Haverkamp et al. (1994) equation, valid only for short to medium times. A total of 264 infiltration measurements performed with a 10cm diameter disc under different soil conditions were used. Compared to the DL procedure, field measurements showed that the NSQE method allowed better estimates of soil hydraulic properties, independently on the infiltration noise and the presence of contact sand layer. Overall, although comparable S values were estimated with both methods, the longer infiltration times allowed by the proposed method made this procedure more accurate estimations of K. In conclusion, the NSQE method have shown to be a significant advance to accurate estimate of the soil hydraulic properties form the transient water flow.This research was supported by the Ministerio de Ciencia e Innovación of Spain (Grant AGL2010- 22050-C03-02) and by the Aragón Regional Government and La Caixa (Grant 2012/GA LC 074).Peer reviewe

Experimental Measurements of Solute Transport and Flow Velocity in a Laboratory Channel

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Testing of a commercial vector network analyzer as low-cost TDR device to measure soil moisture and electrical conductivity

Time Domain Reflectometry (TDR) is a non-destructive technique to determine the soil apparent dielectric constant, εa, the volumetric water content, θ, and bulk electrical conductivity, σ. However, the high cost of TDR devices may limit its use. This study evaluates two different low-cost Vector Network Analyzers (VNA) commercially available (NanoVNA), with 1.5 (VNA1.5) and 3.0 (VNA3.0) GHz maximum operating frequency. NanoVNA can be used for measurements of Frequency Domain Reflectometry (FDR) or, after suitable post-processing, for θ and σ TDR measures. Although FDR and TDR are dual procedures, TDR is easier to interpret for soil experiments. The TDR waveforms and εa measured with NanoVNA connected to 10 and 20 cm length three-rod probes immersed in air, distilled water, and a soil column with different θ were compared to those measured using a TDR100 (Campbell Sci.) instrument. The capacity of VNAs to measure σ was evaluated by immersing a 10 cm length three-rod probe in different NaCl-water solutions. Measurements obtained with the VNA and TDR100 were compared in a field test using two-rod 22 cm length TDR probes inserted in soil plots with increasing water content. A robust fit was observed between TDR waveforms registered with the two VNAs and the TDR100. Although VNA3.0 doubles the frequency range of VNA1.5, both devices allowed for good estimates of εa (εaVNA1.5, 3.0 = 1.001 εaTDR100 – 0.2125; R2 = 0.999). These results indicate that the low-cost VNA devices can measure soil water content with similar accuracy and precision as the TDR100. A good agreement (σVNA1.5, 3.0 = 0.999 σCM + 0.0023; R2 = 0.999) was also observed between the σ measured using a conductivity meter (CM) and that estimated with the VNAs. Finally, a good correlation was also observed between θ measured in the field experiment with TDR100 and the VNA1.5 and VNA3.0 devices

Fingerprinting sediment contribution from alpine soils to mountain reservoirs

6 Pags.- 1 Tabl.- 1 Fig.Soil in alpine environments plays a key role in the development of ecosystem services and information is required on processes that lead to soil erosion to maintain and preserve this important resource. In common with other mountain alpine environments, the Benasque catchment is characterized by temperatures below freezing that can last from November to April, intense rainfall events, and rugged topography which makes assessment of erosion challenging. Indirect approaches to soil erosion assessment offer opportunity to evaluate soil erosion in such areas. In this study sediment fingerprinting procedures were used to evaluate soil sources in the area of the Posets- Maladeta National Park (Central Spanish Pyrenees). Sediment contributions of potential sediment sources defined by soil type (Kastanozems/Phaeozems; Fluvisols and Cambisols) were assessed by different characterizations of sources and identified Fluvisols, which dominate the riparian zone, as the main sediment source at the time of sampling indicating the importance of connectivity and also potential differences in the source dynamic of material in storage versus that transported efficiently from the system during high flows. The approach enabled us to better understand soil erosion processes in the Benasque alpine catchment wherein identified areas that, due to high connectivity, contribute more to sediment deposits.This research was funded by the project CGL2011-25486.Peer reviewe

Spatial and temporal changes in apportionments by using sediment fingerprinting in a Spanish Pyrenean river catchment

1 .pdf with the extended abstract from the Book Abstracts of Assembly.- 1 .pdf copy of the original poster presented by the authors.Central Spanish Pyrenees) and the major sediment sources identified included badlands developed in the middle part of the catchment and the agricultural fields in its lower part. In this study the < 63 m sediment fraction from the channel bed sediment samples from the main rivers (Ésera and Isábena), their tributaries and surface reservoir sediments, the latter spanning two decades, are investigated following the fingerprinting procedure to assess how the land use sediment contributions change along the streams and on time to the reservoir.Peer reviewe

Dos métodos para estimar las propiedades hidráulicas del suelo a partir de: un proceso de (I) humectación por capilaridad más evaporación, y (II) humectación por capilaridad con multitensión: análisis teórico

6 Pags.- 1 Tabl.- 7 Figs. Trabajo originalmente presentado en las XII Jornadas de Investigación en la Zona No Saturada del Suelo (Alcalá de Henares, 18-20 de nov. de 2015). © de los textos: sus autores[ES] La determinación de la curva de retención θ(h) y conductividad hidráulica saturada (Ks) del suelo es fundamental para caracterizar la zona no saturada. Esta comunicación presenta dos métodos para estimar Ks y los parámetros α y n de θ(h) a partir de: (i) un proceso de humectación por capilaridad a saturación seguido de una sobre-presión, más un proceso de evaporación, considerando el fenómeno de histéresis, y (ii) un proceso de humectación por capilaridad a tensión negativa seguida de una tensión a saturación. El análisis inverso se realizó sobre un cilindro de 5 cm de altura y 5 cm de diámetro con suelo franco, utilizando el programa HYDRUS-2D. Los mapas de error de la función objetivo (Ks, α, n) para los planos Ks-α, α-n y Ks-n obtenidos para ambos métodos mostraron un único mínimo, lo que indica que estos métodos permiten estimar de forma precisa los parámetros hidráulicos del suelo.[EN] The determination of the soil water retention curve, θ(h), and the saturated hydraulic conductivity, Ks, are of paramount importance to correctly characterize the vadose zone. This communication presents two methods to estimate Ks and the water retention curve α and n parameters from: (i) a capillary rise wetting process at saturation followed by an overpressure step, plus an evaporation process, taking into account the hysteresis phenomena; and (ii) a capillary wetting process at negative tension plus a saturation step. The theoretical analysis was performed on a 5-cm diameter and 5 cm high cylinder of loam soil, using the HYDRUS-2D software. The responses surfaces of the objective function (Ks, α, n) for the planes Ks-α, α-n and Ks-n obtained with both methods showed a unique and well defined minimum, which indicates these methods allow accurate estimates of the soil hydraulic properties.Este trabajo ha sido financiado por el Ministerio de Economía y Competitividad de España (AGL2010-22050-C03-02).Peer reviewe

Advances in the soil hydraulic properties measurements with the tension infiltrometry technique

sta comunicación presenta varios avances realizados en la t écnica de infiltrometría de tensión. (i) Nuevas bases de disco que permiten medidas de infiltración sin utilizar arena de contacto (disco de base adaptable) o sobre cobertura vegetal (base con forma de sombrero). (ii) Estimación de la conductividad hidráulica (K) y sorptividad (S) del suelo a partir de la solución numérica de la ecuación cuasi- analítica de la curva de infiltración acumulada 3D (NSQE). Los resultados muestran que los prototipos presentados permiten medir de forma satisfactoria la curva de infiltración acumulada de agua en el suelo. Paralelamente, el método NSQE aplicado sobre 400 medidas de infiltración ha re sultado ser robusto y ofrece estimaciones más precisas de K y S.This research was supported by the Ministerio de Ciencia e Innovación of Spain (grant AGL2010-22050-C03-02) and by the Aragón regional government and La Caixa (Grants: GA-LC020/2010; GA-LC006/2008; 2012/ GA LC 074). TPeer Reviewe