Spin and charge transport through driven quantum dot systems and their fluctuations

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica de la Materia Condensada. Fecha de lectura: 04-02-200

Nonlocal quantum heat engines made of hybrid superconducting devices

We discuss a quantum thermal machine that generates power from a thermally driven double quantum dot coupled to normal and superconducting reservoirs. Energy exchange between the dots is mediated by electron-electron interactions. We can distinguish three main mechanisms within the device operation modes. In the Andreev tunneling regime, energy flows in the presence of coherent superposition of zero- and two-particle states. Despite the intrinsic electron-hole symmetry of Andreev processes, we find that the heat engine efficiency increases with increasing coupling to the superconducting reservoir. The second mechanism occurs in the regime of quasiparticle transport. Here we obtain large efficiencies due to the presence of the superconducting gap and the strong energy dependence of the electronic density of states around the gap edges. Finally, in the third regime there exists a competition between Andreev processes and quasiparticle tunneling. Altogether, our results emphasize the importance of both pair tunneling and structured band spectrum for an accurate characterization of the heat engine properties in normal-superconducting coupled dot system

Designing an Advanced Regional Research Network

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Event-driven simulation scheme for spiking neural networks using lookup tables to characterize neuronal dynamics

Nearly all neuronal information processing and interneuronal communication in the brain involves action potentials, or spikes, which drive the short-term synaptic dynamics of neurons, but also their long-term dynamics, via synaptic plasticity. In many brain structures, action potential activity is considered to be sparse. This sparseness of activity has been exploited to reduce the computational cost of large-scale network simulations, through the development of event-driven simulation schemes. However, existing event-driven simulations schemes use extremely simplified neuronal models. Here, we implement and evaluate critically an event-driven algorithm (ED-LUT) that uses precalculated look-up tables to characterize synaptic and neuronal dynamics. This approach enables the use of more complex (and realistic) neuronal models or data in representing the neurons, while retaining the advantage of high-speed simulation. We demonstrate the method's application for neurons containing exponential synaptic conductances, thereby implementing shunting inhibition, a phenomenon that is critical to cellular computation. We also introduce an improved two-stage event-queue algorithm, which allows the simulations to scale efficiently to highly connected networks with arbitrary propagation delays. Finally, the scheme readily accommodates implementation of synaptic plasticity mechanisms that depend on spike timing, enabling future simulations to explore issues of long-term learning and adaptation in large-scale networks.This work has been supported by the EU projects SpikeFORCE (IST-2001-35271), SENSOPAC (IST-028056) and the Spanish National Grant (DPI-2004-07032

A Rapid Electrochemical Impedance Spectroscopy and Sensor-Based Method for Monitoring Freeze-Damage in Tangerines

[EN] This study focuses on the analysis and early detection of freeze-damage in tangerines using a specific double-needle sensor and Electrochemical Impedance Spectroscopy (EIS). Freeze damage may appear in citrus fruits both in the field and in postharvest processes resulting in quality loss and a difficult commercialization of the fruit. EIS has been used to test a set of homogeneous tangerine samples both fresh and later frozen to analyze electrochemical and biological differences. A double-needle electrode associated to a specifically designed electronic device and software has been designed and used to send an AC electric sinusoidal signal 1 V in amplitude and frequency range [100Hz to 1MHz] to the analyzed samples and then receive the electrochemical impedance response. EIS measurements lead to distinct values of both impedance module and phase of fresh and frozen samples over a wide frequency range. Statistical treatment of the received data set by Principal Components Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA) shows a clear classification of the samples depending on the experienced freeze phenomenon, with high sensitivity (1.00), specificity (>= 0.95) and confidence level (95%). Later Artificial Neural Networks (ANN) analysis based on 20-3-1 architecture has allowed to create a mathematical prediction model able to correctly classify 100% of the analyzed samples (CCR =100% for training, validation and test phases, and overall classification), being fast, easy, robust and reliable, and an interesting alternative method to the traditional laboratory analyses.This work was supported by the Spanish Government/FEDER funds [Ministerio de Economia y Empresa (MINECO)/Fondo Europeo de Desarrollo Regional (FEDER)] under Grant RTI2018-100910-B-C43 and in part by the Conselleria d'Educacio, Investigacio, Cultura i Esport de la Generalitat Valenciana under Grant GV/2018/090.Albelda Aparisi, P.; Fortes Sánchez, E.; Contat-Rodrigo, L.; Masot Peris, R.; Laguarda-Miro, N. (2021). A Rapid Electrochemical Impedance Spectroscopy and Sensor-Based Method for Monitoring Freeze-Damage in Tangerines. IEEE Sensors Journal. 21(10):12009-12018. https://doi.org/10.1109/JSEN.2021.3065846S1200912018211

Minimización del impacto ambiental generado por los hoteles de Cartagena a través de la implementación de los requisitos de la NTC 5133:2006 y de prácticas de producciones más limpias

La actividad turística en Colombia, se ha convertido en una de las principales fuentes de ingreso para muchas ciudades y localidades, que son escogidas por los visitantes principalmente por su historia, gastronomía, pero sobretodo por los lugares naturales que por su belleza se presentan como atractivos turísticos. Producto de lo anterior, el auge del crecimiento hotelero y de la actividad turística en el país se ha evidenciado de forma notoria y con él, el impacto generado al medio ambiente como consecuencia de sus actividades. Cartagena es una de las ciudades Colombianas con mayor índice de visitantes durante todo el año, consolidándose desde el siglo XX como el primer centro turístico y de negocios del país.Incluye anexos, bibliografí

Definición de un protocolo para la medida precisa del rango cervical empleando tecnología inercial

[Resumen] Este artículo tiene por objetivo definir un protocolo para la medida precisa del rango articular cervical empleando la tecnología inercial. La utilización de instrumentos de medida, como los goniómetros tradicionales, la fotogrametría o los sensores inerciales permiten una medida objetiva para mejorar el diagnóstico de patologías y su rehabilitación. En este artículo se estudia cual es el mejor posicionamiento de dos sensores e identificamos los factores que influyen en la medida precisa del rango cervical. En el estudio participaron sujetos sin dolor cervical. La medida angular en dos sesiones independientes, siguiendo el protocolo establecido, muestra una diferencia menor a un grado entre ellas, lo que demuestra ser un sistema y protocolo válidos para el objetivo definido al comienzo del trabajo

Parásitos depredadores asociados a jardinería urbana de Valencia

[ES] Este folleto divulgador hace referencia a los parasitoides y depredadores identificados en estudios realizados en diferentes zonas ajardinadas de la zona norte de ValenciaLaborda Cenjor, R.; Rodrigo Santamalia, ME.; Xamani Monserrat, P.; Sanchez Domingo, A. (2013). Parásitos depredadores asociados a jardinería urbana de Valencia. Rafael Laborda Cenjor. http://hdl.handle.net/10251/54935

The Parkinson's disease-associated GPR37 receptor interacts with striatal adenosine A2A receptor controlling its cell surface expression and function in vivo

G protein-coupled receptor 37 (GPR37) is an orphan receptor associated to Parkinson's disease (PD) neuropathology. Here, we identified GPR37 as an inhibitor of adenosine A2A receptor (A2AR) cell surface expression and function in vivo. In addition, we showed that GPR37 and A2AR do oligomerize in the striatum. Thus, a close proximity of GPR37 and A2AR at the postsynaptic level of striatal synapses was observed by double-labelling post-embedding immunogold detection. Indeed, the direct receptor-receptor interaction was further substantiated by proximity ligation in situ assay. Interestingly, GPR37 deletion promoted striatal A2AR cell surface expression that correlated well with an increased A2AR agonist-mediated cAMP accumulation, both in primary striatal neurons and nerve terminals. Furthermore, GPR37−/− mice showed enhanced A2AR agonist-induced catalepsy and an increased response to A2AR antagonist-mediated locomotor activity. Overall, these results revealed a key role for GPR37 controlling A2AR biology in the striatum, which may be relevant for PD management