A comment on "Intergenerational equity: sup, inf, lim sup, and lim inf"

We reexamine the analysis of Chambers (Social Choice and Welfare, 2009), that produces a characterization of a family of social welfare functions in the context of intergenerational equity: namely, those that coincide with either the sup, inf, lim sup, or lim inf rule. Reinforcement, ordinal covariance, and monotonicity jointly identify such class of rules. We show that the addition of a suitable axiom to this three properties permits to characterize each particular rule. A discussion of the respective distinctive properties is provided.Social welfare function; Intergenerational equity; Lim sup ; Lim inf

Rational choice by two sequential criteria

This paper contributes to the theory of rational choice under multiple criteria. We perform a preliminary study of the properties of decision made by the sequential application of rational choices. This is then used to obtain a characterization of set-valued choice functions that are rational by two sequential criteria, which follows the approach initiated by Manzini and Mariotti (Amer. Econ. Rev., 2007) for single-valued choice functions. Uniqueness is not guaranteed but our proof is constructive and an explicit solution is provided in terms of approximation choice functions.Choice function; rational choice; compound function.

Exact renormalization in quantum spin chains

We introduce a real-space exact renormalization group method to find exactly solvable quantum spin chains and their ground states. This method allows us to provide a complete list for exact solutions within SU(2) symmetric quantum spin chains with $S\leq 4$ and nearest-neighbor interactions, as well as examples with S=5. We obtain two classes of solutions: One of them converges to the fixed points of renormalization group and the ground states are matrix product states. Another one does not have renormalization fixed points and the ground states are partially ferromagnetic states.Comment: 8 pages, 5 figures, references added, published versio

Evaluations of inifinite utility streams: Pareto efficient and egalitarian axiomatics

[EN]This investigation focuses on the aggregation of infinite utility streams by social welfare functions. We analyze the possibility of combining Pareto-efficiency and Hammond Equity principles when the feasible utilities for each generation are [0, 1] and the natural numbers. In the latter case, the Hammond Equity ethics can be combined with non-trivial specifications of the Pareto postulate, even through anonymous social welfare functions. As a consequence, any evaluation of infinite utility streams that verifies a mild specification of the Paretian axiom must exert some interference on the affairs of particular generations

Magnetic nanofibers for remotely triggered catalytic activity applied to the degradation of organic pollutants

This work reports on the fabrication and characterization of a novel type of electrospun magnetic nanofibers (MNFs), and their application as a magnetically-activable catalysts for degradation of organic pollutants. The magnetic stimulation capability for the catalytic action is provided by iron-manganese oxide (MnxFe2-xO4) magnetic nanoparticles (MNPs) embedded into electrospun polyacrylonitrile (PAN), which provides stability and chemical resistance. The MNPs (average size d = 40 ± 7 nm) were first obtained by a green and fast sonochemical route, and subsequently embedded into electrospun PAN nanofibers. The final MNFs showed an average diameter of 760 ± 150 nm, providing a superhydrophobic surface with contact angle (θc = 165°), as well as a considerable amount ( 50 % wt.) of embedded MNPs (Mn0.5Fe2.5O4), thermally stable up to temperatures of 330 °C. The catalytic Fe2+/3+/Mn2+/3+/4+ active centers on the MNPs of MNF’s surface could be remotely activated by alternating magnetic fields (AMF) to degrade the methyl blue (MB). Remarkable stability of the MNFs during heating under extreme pH conditions (3 80 %, after several cycles of reusing the same sample without any regeneration process. The capacity of these materials as a catalytic material with magnetic remote activation makes them appealing for those catalytic applications under conditions of darkness or restrained access, where photocatalytic reaction cannot be achieved

Andador con mecanismo de asistencia en operaciones de levantado y sentado de un usuario

Andador (1) con mecanismo de asistencia en operaciones de levantado y sentado de un usuario (21) que comprende una estructura de soporte dotada de medios de desplazamiento (2, 3), un dispositivo de sujeción (20) del usuario al andador y un sistema de bloqueo de los medios de desplazamiento, donde la estructura de soporte comprende al menos un brazo pivotante (14) que guía al dispositivo de sujeción (20) del usuario (21), un soporte guía (11) fijado al andador (1) y que guía al brazo (14) y un módulo de control (15) que controla el sistema de bloqueo de los medios de desplazamiento (2,3) y que comprende medios de selección de un modo de trabajo del andador seleccionado entre “modo andar” y “modo sentarse/levantarse”Peer reviewedConsejo Superior de Investigaciones Científicas, Universidad Politécnica de MadridB1 Patente sin examen previ