3,535 research outputs found
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 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
Variabilidad de la Respuesta de las Células Dendríticas Estimuladas in vitro con Porphyromonas gingivalis y Aggregatibacter actinomycetemcomitans
ResumenLas células dendríticas son células presentadoras de antígeno capaces de inducir la activación y maduración de linfocitos T CD4+ vírgenes hacia un fenotipo efector especifico Th1 o Th2, dependiendo del tipo de antigeno presentado, las senales co-estimuladoras que expresan y el ambiente de citoquinas en el cual se produce la interaccion celula-celula. El objetivo del presente trabajo es analizar la respuesta de las celulas dendriticas estimuladas in vitro con distintas concentraciones de las bacterias periodontopatógenas Pg y Aa. En celulas dendriticas derivadas de monocitos de sangre periferica estimuladas con 101 a 109 bacterias/mL de Pg y Aa se evaluo la expresion del marcador de maduracion CD80 mediante citometria de flujo y de las citoquinas IL1β, IL2, IL5, IL6, IL10, IL12, IL13, IFNγ, TNFα y TNFβ mediante RT-PCR cuantitativa. Aa y Pg indujeron maduracion de las celulas dendriticas, detectandose significativamente mayor expresion de CD80 con la estimulacion de Aa, e indujeron predominantemente la expresion de citoquinas propias de una respuesta Th1. Dependiendo de la carga bacteriana, fueron detectados distintos umbrales de induccion de expresion de citoquinas. Aa indujo la sintesis de IL1β, IL12, IFNγ, TNFα y TNFβ a menor carga bacteriana que Pg. Tomados en conjunto, estos datos nos permiten especular un mayor potencial antigenico y proyectar una mayor capacidad patogenica durante la infeccion periodontal de Aa en comparación a Pg.AbstractDendritic cells are potent antigen-presenting cells able to prime naive T cells and polarize them towards a Th1 or Th2 response, depending on the type of the antigen presented to the TCR, the type of costimulatory signals, and the cytokine pattern in the environment. The aim of this work was to analyze the response of dendritic cells to in vitro stimulation with Pg and Aa. In monocyte-derived dendritic cells stimulated with 101 to 109 bacteria/mL of Pg or Aa were evaluated both the expression of the maturation marker CD80 by flow cytometry and the expression of the cytokines IL1β, IL2, IL5, IL6, IL10, IL12, IL13, IFNγ, TNFα and TNFβ by quantitative RT-PCR. Both Pg and Aa led to dendritic cell maturation, detecting higher CD80 expression upon Aa-stimulation, and induced a Th1 pattern of cytokine expression. Aa-stimulated dendritic cells expressed IL1β, IL12, IFNγ, TNFα and TNFβ mRNAs with lower bacterial charge than with Pg. Furthermore, our data indicated the existence of distinct thresholds for the induction of the different cytokines analyzed. Taken together, these data allow us to speculate a higher antigenic potential and higher pathogenic capacity of Aa than Pg during periodontal infections
Sequential rationalization of multivalued choice
[EN]This paper contributes to the theory of rational choice under sequential
criteria. Following the approach initiated by Manzini and Mariotti (2007)
for single-valued choice functions, we characterize choice correspondences
that are rational by two sequential criteria under a mild consistency axiom.
Rationales ensuring the sequential rationalization are explicitly constructed
and a uniquely determined, canonical solution is provided
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
Optical mirages from spinless beams
Spin-orbit interactions of light are ubiquitous in multiple branches of
nanophotonics, including optical wave localization. In that framework, it is
widely accepted that circularly polarized beams lead to spin-dependent apparent
shifts of dipolar targets commonly referred to as optical mirages. In contrast,
these optical mirages vanish when the illumination comes from a spinless beam
such as a linearly polarized wave. Here we show that optical localization
errors emerge for particles sustaining electric and magnetic dipolar response
under the illumination of spinless beams. As an example, we calculate the
optical mirage for the scattering by a high refractive index nanosphere under
the illumination of a linearly polarized plane wave carrying null spin,
orbital, and total angular momentum. Our results point to an overlooked
interference between the electric and magnetic dipoles rather than the
spin-orbit interactions of light as the origin for the tilted position of the
nanosphere
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