Reference Points Based on Dynamic Optimisation: A Versatil Algorithm for Mixed Fishery Management with Bio-economic Agestructured Models

Single-species management objectives may not be consistent within mixed fisheries. They may lead species to unsafe situations, promote discarding of over-quota and/or misreporting of catches. We provide an algorithm for characterising bio-economic reference points for a mixed fishery as the steady-state solution of a dynamic optimal management problem. The optimisation problem takes into account: i) that species are fishing simultaneously in unselective fishing operations and ii)intertemporal discounting and fleet costs to relate reference points to discounted economic profits along optimal trajectories. We illustrate how the algorithm can be implemented by applying it to the European Northern Stock of Hake (Merluccius merluccius), where fleets also capture Northern megrim (Lepidorhombus whiffiagonis) and Northern anglerfish (Lophius piscatorius and Lophius budegassa). We find that optimal mixed management leads to a target reference point that is quite similar to the 2/3 of the Fmsy single-species (hake) target. Mixed management is superior to singlespecies management because it leads the fishery to higher discounted profits with higher long-term SSB for all species. We calculate that the losses due to the use of the Fmsy single-species (hake) target in this mixed fishery account for 11.4% of total discounted profits.

Generating cluster submodels from a multistage stochastic mixed integer optimization model using break stage

We present a scheme to generate clusters submodels with stage ordering from a (symmetric or a nonsymmetric one) multistage stochastic mixed integer optimization model using break stage. We consider a stochastic model in compact representation and MPS format with a known scenario tree. The cluster submodels are built by storing first the 0-1 the variables, stage by stage, and then the continuous ones, also stage by stage. A C++ experimental code has been implemented for reordering the stochastic model as well as the cluster decomposition after the relaxation of the non-anticipativiy constraints until the so-called breakstage. The computational experience shows better performance of the stage ordering in terms of elapsed time in a randomly generated testbed of multistage stochastic mixed integer problems.

Helmholtz Fermi surface harmonics: an efficient approach for treating anisotropic problems involving Fermi surface integrals

We present a new efficient numerical approach for representing anisotropic physical quantities and/or matrix elements defined on the Fermi surface (FS) of metallic materials. The method introduces a set of numerically calculated generalized orthonormal functions which are the solutions of the Helmholtz equation defined on the FS. Noteworthy, many properties of our proposed basis set are also shared by the FS harmonics introduced by Philip B Allen (1976 Phys. Rev. B 13 1416), proposed to be constructed as polynomials of the cartesian components of the electronic velocity. The main motivation of both approaches is identical, to handle anisotropic problems efficiently. However, in our approach the basis set is defined as the eigenfunctions of a differential operator and several desirable properties are introduced by construction. The method is demonstrated to be very robust in handling problems with any crystal structure or topology of the FS, and the periodicity of the reciprocal space is treated as a boundary condition for our Helmholtz equation. We illustrate the method by analysing the free-electron-like lithium (Li), sodium (Na), copper (Cu), lead (Pb), tungsten (W) and magnesium diboride (MgB2)

The Stability of the Roommate Problem Revisited

The lack of stability in some matching problems suggests that alternative solution concepts to the core might be applied to find predictable matchings. We propose the absorbing sets as a solution for the class of roommate problems with strict preferences. This solution, which always exists, either gives the matchings in the core or predicts some other matchings when the core is empty. Furthermore, it satisfies an interesting property of outer stability. We also characterize the absorbing sets, determine their number and, in case of multiplicity, we find that they all share a similar structure.

El arte de registrar. La importancia de los registros de enfermería

[ES]La literatura especializada coincide en señalar serios problemas en los registros de enfermería. Se registra mal por muchos motivos: por desconocimiento, por inexperiencia, por la idea de que es una tarea burocrática y ajena, y sobre todo por una idea distorsionada del rol de la enfermería. Un registro adecuado contribuye no sólo a la calidad de los cuidados, sino que hace visible el trabajo que enfermería realiza y puede contribuir a desarrollar la disciplina enfermera y reforzar su rol independiente. En este trabajo se analiza, a partir de la literatura especializada, el problema de los registros de enfermería: los problemas más frecuentes y sus causas, la perspectiva de las enfermeras sobre los registros, los problemas éticos y legales que implican y las posibles soluciones para una nueva manera de registrar.

Hasierako alfabetatzea: Hizkuntza idatziaren zailtasunak eta arazoak

Haur batzuek hasierako alfabetatzean, hizkuntza idatziarekin zenbait arazo izaten dituzte. Arazo horiek, normalean, ikaskuntza prozesuaren baitan dauden akatsak izaten dira, baina batzuetan hizkuntza trastorno baten adierazleak bihurtu daitezke. Hori dela eta, irakasleak, ahal duen neurrian, arazo horiek aurreikusten saiatu behar du. Ikerketa honetan, haurrek izaten dituzten akatsez gain, eskolek eta irakasleek irakaskuntza honetan dituzten gabeziak eta arazoak aztertu dira. Datuak baloratu ostean, haurrek euren artean mota bereko akatsak egiten dituztela eta irakasleek hizkuntza idatziaren oinarrizko kontzeptuekin zailtasunak dituztela ikusi da. Horrez gain, erabiltzen dituzten metodoak haurren ikaskuntza prozesua errazten ez dutela ikusi dugu. Hori guztia dela eta, arazoak eta gabeziak aurreikusteko proposamen bat aurkeztu dugu.

Problemen Ebazpena Lehen Hezkuntzan

Lan honen helburua, EAE-ko curriculuma oinarritzat hartuz, Lehen Hezkuntzako testuliburuetan sormena eta intuizioa garatzen diren problemak lantzen diren, aztertu eta analizatzea da. Horrez gain, testuliburuan atal honetan gabeziak dituzten haur talde batean, mota hauetako problemak praktikan jarriko dira, beraien jarrera eta erantzuna aztertuz.