A fractional porous medium equation

We develop a theory of existence, uniqueness and regularity for a porous medium equation with fractional diffusion, $\frac{\partial u}{\partial t} + (-\Delta)^{1/2} (|u|^{m-1}u)=0$ in $\mathbb{R}^N$, with $m>m_*=(N-1)/N$, $N\ge1$ and $f\in L^1(\mathbb{R}^N)$. An $L^1$-contraction semigroup is constructed and the continuous dependence on data and exponent is established. Nonnegative solutions are proved to be continuous and strictly positive for all $x\in\mathbb{R}^N$, $t>0$

Distinct expressions of the BSR using various frequencies offshore Uruguay and its correspondence with the gas hydrate stability zone

At the Uruguayan continental margin, seismic evidence for the occurrence of gas hydrate has been identified based on the presence of BSRs in densely spaced 2D reflection seismic sections from different surveys. Mapping of BSRs based on 2D seismic data acquired in 2007 and 2008 suggested the presence of gas hydrates in areas that were not previously identified; hence hydrate occurrence offshore Uruguay is more widespread than previously thought. Recently ANCAP has digitized offshore seismic data acquired between 1970 and 1982. Being able to work on this data using interpretation software, and integrating results with the latest interpretations performed on the seismic collected in 2007 and 2008, the BSR extends over an area of approximately 25.000 km2. It is present in water depths greater than 500 m and has high continuity in Pelotas Basin but is more discontinuous at Punta del Este Basin and southern part of Oriental del Plata Basin. In offshore basins around the world the base of GHSZ can have different seismic expressions such as continuous, segmented, and high-relief BSRs depending on the stratigraphic, fluid and geothermal setting. Here, we present examples of the influence of the acquisition parameters on the acoustic expression of the BSR, comparing commercial seismic sections acquired for hydrocarbon exploration and high resolution seismic sections acquired during the R/V Meteor Cruise M49/2 in 2001 and R/V Meteor Cruise M78/3a (May - June 2009) using different sources and streamer system. For the different data sets the BSR presents differences regarding its continuity and amplitude strength. In high resolution seismic, enhanced amplitudes and phase reversals are observed for several reflectors while deep penetration seismic shows only one single continuous reflector. This comparison may help to visualize the complexity of the free gas, gas hydrate and stratigraphic system behind the BSR, which is usually masked on low-frequency deep penetration seismic data

Sustainable Irrigation in Agriculture: An Analysis of Global Research

Irrigated agriculture plays a fundamental role as a supplier of food and raw materials. However, it is also the world’s largest water user. In recent years, there has been an increase in the number of studies analyzing agricultural irrigation from the perspective of sustainability with a focus on its environmental, economic, and social impacts. This study seeks to analyze the dynamics of global research in sustainable irrigation in agriculture between 1999 and 2018, including the main agents promoting it and the topics that have received the most attention. To do this, a review and a bibliometric analysis were carried out on a sample of 713 articles. The results show that sustainability is a line of study that is becoming increasingly more prominent within research in irrigation. The study also reveals the existence of substantial differences and preferred topics in the research undertaken by different countries. The priority issues addressed in the research were climatic change, environmental impact, and natural resources conservation; unconventional water resources; irrigation technology and innovation; and water use efficiency. Finally, the findings indicate a series of areas related to sustainable irrigation in agriculture in which research should be promoted

Election of Water Resources Management Entity Using a Multi-Criteria Decision (MCD) Method in Salta Province (Argentine)

At present, the water resources are a strategic element each time more necessary and limited becoming a source of conflicts. For that, it is fundamental to create an independent and competent entity with good reputation and social acceptation. This entity must be able to obtain, store and process all data dispersed in different entities creating a network for these purposes. Finally, it must be able to organize different branches between the government and the final users. Using one of the wellknown Multicriteria Decision Methods(MCDM) with several realistic alternatives and several criteria identified in expert seminars in Salta and Madrid, we have obtained hopeful results and more recently new modifications introduced have generated better results

The “Planes de Acción Comercial” of the Community of Valencia. Evaluation of the Alicante and Elche cases

Con la intención de aunar los estudios comerciales con los urbanísticos en las ciudades valencianas, el Consejo Superior de Cámaras de Comercio de la Comunidad Valenciana desarrolló los Planes de Acción Comercial (PAC) en las principales ciudades de la provincia de Alicante. Estos documentos consultivos, realizados para impulsar la investigación urbana y comercial a escala local, han pretendido orientar, proponer y financiar actuaciones de intervención a las administraciones locales. En este artículo, se revisa la trayectoria de los PAC y se analizan, en especial, los resultados de las acciones llevadas a cabo en las ciudades de Alicante y Elche, con el objetivo de conocer el estado de situación de estas propuestas urbano-comerciales.In order to homogenize the urban studies in the Valencian cities and towns, Urban-Commercial Action Plans (CAP) have been promoted by the regional government of Valencia (Spain). These consultative documents, made to promote urban and commercial research at a local scale basis, have sought to guide, propose and finance actions concerning the local government intervention. We present a revision of the trajectory of the PAC and analyse, in particular, the results of the activities carried out in the cities of Alicante and Elche with the objective of update the state of the art about these commercial urban proposals.El presente texto se incardina en el proyecto de investigación Las ciudades españolas en la etapa autonómica (1978-2012). Dinámicas, procesos y políticas (URBSPAIN), financiado por el Plan Nacional de Investigación I+D+i del Ministerio de Economía y Competitividad para el período 2010-2013 (Código CSO 2009-11261-Subpr. GEOG)

Computer based trainer for signal and systems undergraduate students

University students demand many exercises for practicing during their undergraduate courses. Although there are many resources where they can find proposed exercises, specially for basic courses, these resources include a fixed and limited set of proposed exercises. The students usually want to repeat similar exercises till they are sure they have the skill to solve it. Additionally they demand fast feedback about their trials. With the development of the European Higher Education Area, the work of the students must be assessed and this could be seen as a higher workload for the instructors, so the development of tools that help in the assignment and assessment of students work is necessary. Here, a tool that automatically generates thousands of numerical and wording variations of the same exercise and automatically assesses the solution given by the student is presented. The selected exercise is the convolution of two signals, a basic exercise for Signals and Systems undergraduate course for Electrical and Electronic Engineering students. Wording variations of the exercise include discrete time and continuous time signals, to find the output of a linear and invariant system for a given input and different presentations of the signals (analytic expressions, graphical or tabulated representation for the time span where the signals have non zero values). Both wording and numerical variations are obtained from a single seed. The remainders of division of the seed by different divisors are calculated and used to obtain a large set of variations of the exercise. One of these remainders is used to group the variations of the exercise by difficulty grade. The teacher can use this tool to automatically assign personalized exercises for each student that attends his/her course. This personalized assignment makes the cheating among students more difficult than when the same exercise is assigned to all the students. The teacher can be sure that all the assignments are in the same difficulty group. Moreover, this tool automatically grades the solution given by the student, so can be used as an assessment tool by the teacher. The basic algorithm to generate the variations in this exercise could be extended to almost all typical exercises in Signal and Systems cours

La banda de Möbius: un camino que te llevará de cabeza

Este artículo se ha escrito con el objetivo de mostrar la superficie geométrica denominada banda de Möbius como herramienta para potenciar la motivación e interés de los alumnos, tanto de bachillerato como universitarios, en sus clases de Matemáticas. Esta superficie, que tiene varias propiedades muy curiosas, es en realidad un bucle girado, normalmente hecho de papel, fácilmente manipulable por los estudiantes. Para su construcción únicamente se necesitan lápiz, papel, pegamento y tijeras.The goal of this paper is to show a geometrical surface named Möbius Band as an useful tool to achieve the motivation and interest from Secondary or university students when facing their mathematical classes. This surface, which has several strange properties is in fact a twisted loop which can be easily manipulated by students. To construct it, strips of paper, sticky type, scissors and a pen are only needed

Short-term synaptic plasticity regulates the level of olivocochlear inhibition to auditory hair cells

In the mammalian inner ear, the gain control of auditory inputs is exerted by medial olivocochlear (MOC) neurons that innervate cochlear outer hair cells (OHCs). OHCs mechanically amplify the incoming sound waves by virtue of their electromotile properties while the MOC system reduces the gain of auditory inputs by inhibiting OHC function. How this process is orchestrated at the synaptic level remains unknown. In the present study, MOC firing was evoked by electrical stimulation in an isolated mouse cochlear preparation, while OHCs postsynaptic responses were monitored by whole-cell recordings. These recordings confirmed that electrically evoked IPSCs (eIPSCs) are mediated solely by α9β10 nAChRs functionally coupled to calcium-activated SK2 channels. Synaptic release occurred with low probability when MOC-OHC synapses were stimulated at 1 Hz. However, as the stimulation frequency was raised, the reliability of release increased due to presynaptic facilitation. In addition, the relatively slow decay of eIPSCs gave rise to temporal summation at stimulation frequencies >10 Hz. The combined effect of facilitation and summation resulted in a frequency-dependent increase in the average amplitude of inhibitory currents in OHCs. Thus, we have demonstrated that short-term plasticity is responsible for shaping MOC inhibition and, therefore, encodes the transfer function from efferent firing frequency to the gain of the cochlear amplifier.Fil: Ballestero, Jimena Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Zorrilla de San Martín, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Goutman, Juan Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Elgoyhen, Ana Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Fuchs, Paul A.. The Johns Hopkins University School of Medicine; Estados UnidosFil: Katz, Eleonora. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; Argentin