Quick Analysis of Organic Amendments via Portable X-ray Fluorescence Spectrometry

The determination of heavy metals in soils and organic amendments, such as compost, manure, biofertilizer, and sludge, generally involves the digestion of samples with aqua regia, and the determination of those in the solution using various techniques. Portable X-ray fluorescence (PXRF) has many advantages in relation to traditional analytical techniques. However, PXRF determines the total elemental content and, until now, its use for the analysis of organic amendments has been limited. The objective of this work is the calibration of a PXRF instrument to determine the aqua regia-soluble elemental contents directly in solid samples of organic amendments. Our proposal will avoid the digestion step and the use of other laboratory techniques. Using a training set of samples, calibration functions were obtained that allow the determination of the aqua regia-soluble contents from the PXRF readings of total contents. The calibration functions (obtained by multiple linear regression) allowed the quantitative determination of the aqua regia-soluble contents of Fe, K, P, S, Zn, Cu, Pb, Sr, Cr, and Mn, as well as the organic matter content and a semi-quantitative assessment of Al, Ca, V, Ba, Ni, and As contents. The readings of Si, Fe, Al, Ca, K, or S were used as correction factors, indicating that the calibrations functions found are truly based on the chemical composition of the sample matrix. This study will allow a fast, cheap, and reliable field analysis of organic amendments and of other biomass-based materials.Spanish Ministry of Science, Innovation and Universities, and the European Regional Development Fund, European Union, (AEI/FEDER, UE), grant number CGL2016-78937-R

The fishbowl. A Critical reflection between teachers and Master's students in two interactive LS plans. An experience at the University of Malaga.

The paper aims to present the experience of convergence between two simultaneous and interactive processes of LS development in a Master of Educational Innovation at the University of Malaga in Spain to stimulate the development of critical thinking in education.Purpose- The paper aims to present the experience of convergence between two simultaneous and interactive processes of LS development in a Master of Educational Innovation at the University of Malaga in Spain. Design- Case study of an educational experience in the University context. It involves a group of 30 students, two subjects and 3 teachers. Description: The first version of the experience began 10 years ago (Soto, Serván and Pérez, 2015) Three years ago, the three lecturers set out to incorporate LS as a structure for this task in order to stimulate the development of critical thinking and to improve the tutoring of this work, developing our own teaching task as an explicit LS process. Findings: Among the most significant findings of this dual, parallel and interactive LS process, we can highlight: - The substantive increase in motivation of both students and teachers. - The complexity of integrating and harmonising the roles of observation-inquiry and teaching-by the students and, in the case of teachers, increased by the need to evaluate the learning process developed by the students themselves. - The extraordinary influence of what we have called the fishbowl effect. That is to say, the linking of the two final phases of the LS, placing themselves in the centre of the circle and openly exposing their perception of the weaknesses and strengths of their LS process, has stimulated a powerful simultaneous process of reflection and critical self-evaluation among the components of the small group, which has been strengthened by the final presentation of the teachers' reflections on their own LS. Relevance: The importance of generating simultaneous and interactive LS processes between teachers and students in initial teacher training. Especially the teachers' fishbowl effect, for their strong modeling influence, is so relevant that it appears in all student’s portfolios as one of the most impacting models for their teacher education process.Universidad de Málaga. Campus de Excelencia Internaciona Andalucía Tec

A fast P system for finding a balanced 2-partition

Numerical problems are not very frequently addressed in the P systems literature. In this paper we present an effective solution to the 2-Partition problem via a family of deterministic P systems with active membranes using 2-division. The design of this solution is a sequel of several previous works on other problems, mainly on the Subset-Sum and the Knapsack problems. Several improvements are introduced and explained.Ministerio de Ciencia y Tecnología TIC2002-04220-C03-0

On Descriptive Complexity of P Systems

In this paper we address the problem of describing the complexity of the evolution of a P system. This issue is is specially hard in the case of P systems with active membranes, where the number of steps of a computation is not sufficient to evaluate the complexity. Sevilla carpets were introduced in [1], and they describe the space-time complexity of P systems. Based on them, we define some new parameters which can be used to compare evolutions of P systems. To illustrate this, we also include two different cellular solutions to the Subset Sum problem and compare them via these new parameters.Ministerio de Ciencia y Tecnología TIC2002-04220-C03-0

Available Membrane Computing Software

The simulation of a P system with current computers is a quite com-plex task. P systems are intrinsically nondeterministic computational devices and therefore their computation trees are di±cult to store and handle with computers with one processor (or a bounded number of processors). Nevertheless, there exists a ¯rst generation of simulators which can be successfully used for pedagogical pur-poses and as assistant tools for researchers. This chapter summarizes some of these simulators, presenting the state of the art of the available software for simulating (di®erent variants of) cell-like membrane systems.Ministerio de Ciencia y Tecnología TIC2002-04220-C03-0

Towards a Programming Language in Cellular Computing

Several solutions to hard numerical problems using P systems have been presented recently, and strong similarities in their designs have been no- ticed. In this paper we present a new solution, an e®ective one to the Partition problem via a family of deterministic P systems with active membranes using 2-division. We intend to show that the idea of a cellular programming lan- guage is possible, indicating some \subroutines" that can be used in a variety of situations and therefore could be useful for attacking new problems in the future.Ministerio de Ciencia y Tecnología TIC2002-04220-C03-0

A Simulator for Confluent P Systems

Software simulators for P system are nowadays the main tool to carry out experiments in the field of Membrane Computing. Although the simulation of a P system is a quite complex task, current simulators have been successfully used for pedagogical purposes and also as assistant tools for researchers. Up to now, simulators have always been designed to deal with a specific model of P systems. In this paper we present a new simulator which is not oriented to only one model of systems, but it allows the researcher to experiment with many existing models or even to create new ones.Ministerio de Ciencia y Tecnología TIC2002-04220-C03-0

An Approach to the Degree of Parallelism in P Systems

In the literature, several designs of P systems were used for performing the same task. The use of different techniques or even different P system models makes it very difficult to compare these designs. In this paper, we introduce a new criterion for such a comparison: the degree of parallelism of a P system. To this aim, we define the labeled dependency graph associated with a P system, and we use this new concept for proving some results concerning the maximum number of applications of rules in a single step along the computation of a P system.Ministerio de Educación y Ciencia TIN2005-09345-C04-0