Localization transition induced by learning in random searches

We solve an adaptive search model where a random walker or L\'evy flight stochastically resets to previously visited sites on a $d$-dimensional lattice containing one trapping site. Due to reinforcement, a phase transition occurs when the resetting rate crosses a threshold above which non-diffusive stationary states emerge, localized around the inhomogeneity. The threshold depends on the trapping strength and on the walker's return probability in the memoryless case. The transition belongs to the same class as the self-consistent theory of Anderson localization. These results show that similarly to many living organisms and unlike the well-studied Markovian walks, non-Markov movement processes can allow agents to learn about their environment and promise to bring adaptive solutions in search tasks.Comment: 5 pages, 5 figures + 4 pages of Supplemental Information. Accepted in Physical Review Letter

Wave-vortex interaction

We present an experimental study on the effect of a electromagneticaly generated vortex flow on parametrically amplified waves at the surface of a fluid. The underlying vortex flow, generated by a periodic Lorentz force, creates spatio-temporal fluctuations that interact nonlinearly with the standing surface waves. We characterize the bifurcation diagram and measure the power spectrum density (PSD) of the local surface wave amplitude. We show that the parametric instability threshold increases with increasing intensity of the vortex flow.Comment: 8 pages, 10 figures, submitted to Phys. Rev.

Diseño de prototipos experimentales orientados al aprendizaje de la optica

Se presenta un conjunto de prototipos experimentales para el aprendizaje de la óptica. Los prototipos fueron elaborados con materiales de bajo costo y de fácil adquisición, mejorados en sus diseños, validados por expertos y probados en el aula para su valoración. Con ellos se recreó una metodología sustentada en constructos y procesos que mejoró el logro de los alumnos, mostrando su pertinencia y efectividad para la enseñanza de la óptica.Palabras Claves: Enseñanza de la Física; óptica; didáctica; diseño de Prototipos.Desing experimental prototype oriented learning opticsWe should an experimental prototypes set for learning optics. The prototypes were developed with materials affordable and easy acquisition, improved their designs, validated by experts and tested in the classroom for their valuation. They recreated a methodology based on “building” and processes that improves the achievement of the students, showing their relevance and effectiveness for the teaching of optics.Key Words: The teaching of Physical; Optics; Experimental Prototype

Fluctuations of energy flux in a simple dissipative out-of-equilibrium system

We report the statistical properties of the fluctuations of the energy flux in an electronic RC circuit driven with a stochastic voltage. The fluctuations of the power injected in the circuit are measured as a function of the damping rate and the forcing parameters. We show that its distribution exhibits a cusp close to zero and two asymmetric exponential tails, the asymmetry being driven by the mean dissipation. This simple experiment allows to capture the qualitative features of the energy flux distribution observed in more complex dissipative systems. We also show that the large fluctuations of injected power averaged on a time lag do not verify the Fluctuation Theorem even for long averaging time. This is in contrast with the findings of previous experiments due to their small range of explored fluctuation amplitude. The injected power in a system of N components either correlated or not is also studied to mimic systems with large number of particles, such as in a dilute granular gas.Comment: to be published in Phys. Rev.

Fluctuations of energy flux in wave turbulence

We report that the power driving gravity and capillary wave turbulence in a statistically stationary regime displays fluctuations much stronger than its mean value. We show that its probability density function (PDF) has a most probable value close to zero and involves two asymmetric roughly exponential tails. We understand the qualitative features of the PDF using a simple Langevin type model.Comment: submitted to PR

The Fornax Deep Survey with VST. VIII. Connecting the accretion history with the cluster density

This work is based on deep multi-band (g, r, i) data from the Fornax Deep Survey with VST. We analyse the surface brightness profiles of the 19 bright ETGs inside the virial radius of the Fornax cluster. The main aim of this work is to identify signatures of accretion onto galaxies by studying the presence of outer stellar halos, and understand their nature and occurrence. Our analysis also provides a new and accurate estimate of the intra-cluster light inside the virial radius of Fornax. We performed multi-component fits to the azimuthally averaged surface brightness profiles available for all sample galaxies. This allows to quantify the relative weight of all components in the galaxy structure that contribute to the total light. In addition, we derived the average g-i colours in each component identified by the fit, as well as the azimuthally averaged g-i colour profiles, to correlate them with the stellar mass of each galaxy and the location inside the cluster. We find that in the most massive and reddest ETGs the fraction of light in, probably accreted, halos is much larger than in the other galaxies. Less-massive galaxies have an accreted mass fraction lower than 30%, bluer colours and reside in the low-density regions of the cluster. Inside the virial radius of the cluster, the total luminosity of the intra-cluster light, compared with the total luminosity of all cluster members, is about 34%. Inside the Fornax cluster there is a clear correlation between the amount of accreted material in the stellar halos of galaxies and the density of the environment in which those galaxies reside. By comparing this quantity with theoretical predictions and previous observational estimates, there is a clear indication that the driving factor for the accretion process is the total stellar mass of the galaxy, in agreement with the hierarchical accretion scenario.Comment: 18 pages, 10 figures. Accepted for publication in A&

Peritoneal protein transport during the baseline peritoneal equilibration test is an accurate predictor of the outcome of peritoneal dialysis patients

[Abstract] Background: Peritoneal protein excretion (PPE) is a potential marker of the outcome in peritoneal dialysis (PD) patients. Method: Observational study of a cohort of 269 patients starting PD in a single unit. Study variables: total PPE during a baseline peritoneal equilibration test (PET; PET-PPE) and 24-hour PPE. Control variables: essential baseline demographic, laboratory and adequacy markers. Main outcomes: mortality, cardiovascular events and risk of peritonitis. We applied univariate and multivariate strategies of survival analysis. Main Results: PET-PPE sustained a significant, yet limited correlation with 24-hour PPE (r = 0.46, p < 0.0005). At baseline, the main study variables showed an independent correlation with peritoneal transport characteristics (D/P240’ creatinine) and cardiovascular comorbidity. PET-PPE (p < 0.0005, model global χ2 59.4) was a more accurate predictor of overall mortality than 24-hour PPE (p = 0.04, χ2 50.5). Moreover, PPE during PET, but not 24-hour PPE, was an independent predictor of the risks of cardiovascular and infectious mortality, and of peritonitis. Conclusions: Baseline PPE represents a strong independent marker of survival of PD patients. Estimation of PPE during PET is more accurate than 24-hour PPE for this purpose, sustains a definite independent association with cardiovascular and infectious mortality, and shows a significant correlation with the risk of peritonitis

Realidad jurídico-laboral en el aula. Guías de trabajo autónomo con medios audiovisuales

This article wants to show an innovative project in the teaching of legal subjects in their side of formal proceedings, so the students could practise using their knowledge of the substantive law, a completed diagnosis of a case, and be able to provide adequate legal guidance to the legal practice. The objective is inter relation they theoretic knowledge that they have learned in the classroom with their effective implementation at the practical reality, pursuing convergence with the European Higher Education Area. Help to promote self-employment and student self-learning, including the strengthening and updating the necessary innovation in teaching and learning methodologies, using new information technologies and communication applied to teaching, consisting of actual recordings of subjects in relation to the course that we have begun to apply the labour process.Este artículo pretende mostrar un proyecto innovador en la enseñanza de asignaturas jurídicas, en su vertiente procesal o de carácter formal, para que el alumno pueda realizar, una vez que conoce el derecho sustantivo, un completo diagnóstico de un caso concreto, y ser capaz de dar la orientación jurídica adecuada a la práctica jurídica. El objetivo es que interrelacionen los conocimientos teóricos que van adquiriendo en el aula con su aplicación efectiva a la realidad práctica, persiguiéndose la convergencia con el Espacio Europeo de Educación Superior. Contribuye a la promoción del trabajo autónomo y autoaprendizaje del alumno, fortaleciendo además la necesaria innovación y actualización en metodologías de enseñanza-aprendizaje, utilizando las nuevas tecnologías de la información y la comunicación aplicadas a la docencia, consistentes en grabaciones reales de materias en relación a la asignatura a la que lo hemos empezado a aplicar, el Proceso Laboral

An updated MILES stellar library and stellar population models

(Aims) We present a number of improvements to the MILES library and stellar population models. We correct some small errors in the radial velocities of the stars, measure the spectral resolution of the library and models more accurately, and give a better absolute flux calibration of the models. (Methods) We use cross-correlation techniques to correct the radial velocities of the offset stars and the penalised pixel-fitting method, together with different sets of stellar templates, to re-assess the spectral resolution of the MILES stellar library and models. We have also re-calibrated the zero-point flux level of the models using a new calibration scheme. (Results) The end result is an even more homogeneously calibrated stellar library than the originally released one, with a measured spectral resolution of ~2.5\AA, almost constant with wavelength, for both the MILES stellar library and models. Furthermore, the new absolute flux calibration for the spectra excellently agrees with predictions based on independent photometric libraries. (Conclusions) This improved version of the MILES library and models (version 9.1) is available at the project's website (http://miles.iac.es).Comment: 7 pages, 8 figures. Accepted for publication in Astronomy & Astrophysics (Research Note

Percepción y conocimientos de los médicos veterinarios de Lima Metropolitana sobre el uso de fitocannabinoides de uso medicinal en animales de compañía

The aim of this study was to determine the perception and knowledge of veterinary practitioners in Metropolitan Lima on the use of phytocannabinoids for medicinal use in companion animals. An anonymous and voluntary survey was carried out on professionals who worked in veterinary centres in various districts of Lima, obtaining 151 surveys. Among the respondents, 56.3% (85) were women, the average age was 33.0 years and the average professional practice time was 7.1 years. The 85.4% (129) had heard about phytocannabinoids and, of these, 74.8% (113) knew that they are used in veterinary medicine. The most recognized medicinal uses in humans and animals were as antiepileptic, analgesic, and palliative in cancer patients. Of the respondents, 79.5% (120) considered that they should be beneficial, 18.5% (28) had the answer “maybe” and 2% (3) did not consider them beneficial. According to the Chi square test, there was no association between knowledge and the demographic variables evaluated. The study shows that there is a favourable perception in the majority of veterinary professionals surveyed regarding the use of these cannabinoids in clinical practice, but knowledge about this is still incipient.El objetivo del estudio fue determinar la percepción y conocimientos de los médicos veterinarios de Lima Metropolitana sobre el uso de fitocannabinoides de uso medicinal en animales de compañía. Se realizó una encuesta anónima y voluntaria a los médicos que laboraban en centros veterinarios de varios distritos de Lima obteniendo 151 encuestas. El 56.3% (85) fueron mujeres, la edad promedio fue de 33.0 años y el tiempo de ejercicio profesional promedio fue de 7.1 años. El 85.4% (129) había escuchado acerca de los fitocannabinoides y, de ellos, el 74.8% (113) sabía que son usados en medicina veterinaria. Los usos medicinales más reconocidos en humanos y animales fueron como antiepiléptico, analgésico y paliativo en pacientes con cáncer. De los encuestados, el 79.5% (120) consideró que deben ser beneficiosos, el 18.5% (28) tuvo como respuesta “tal vez” y el 2% (3) no los consideró beneficiosos. Según la prueba de Chi cuadrado no hubo asociación entre conocimiento y las variables demográficas evaluadas. El estudio muestra que existe una percepción favorable en la mayoría de los médicos veterinarios encuestados respecto al uso de estos cannabinoides en la clínica práctica, pero el conocimiento al respecto es aún incipiente