11,610 research outputs found

    Down or out: assessing the welfare costs of household investment mistakes

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    This paper investigates the efficiency of household investment decisions in a unique dataset containing the disaggregated wealth and income of the entire population of Sweeden.asset allocation; diversification; familiarity; participation

    Non-Boolean almost perfect nonlinear functions on non-Abelian groups

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    The purpose of this paper is to present the extended definitions and characterizations of the classical notions of APN and maximum nonlinear Boolean functions to deal with the case of mappings from a finite group K to another one N with the possibility that one or both groups are non-Abelian.Comment: 17 page

    Down or Out: Assessing the Welfare Costs of Household Investment Mistakes

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    This paper investigates the efficiency of household investment decisions in a unique dataset containing the disaggregated wealth and income of the entire population of Sweden. The analysis focuses on two main sources of inefficiency in the financial portfolio: underdiversification of risky assets (“down”) and nonparticipation in risky asset markets (“out”). We find that while a few households are very poorly diversified, the cost of diversification mistakes is quite modest for most of the population. For instance, a majority of participating Swedish households are sufficiently diversified internationally to outperform the Sharpe ratio of their domestic stock market. We document that households with greater financial sophistication tend to invest more efficiently but also more aggressively, so the welfare cost of portfolio inefficiency tends to be greater for these households. The welfare cost of nonparticipation is smaller by almost one half when we take account of the fact that nonparticipants would be unlikely to invest efficiently if they participated in risky asset markets.

    A novel numerical mechanical model for the stress–strain distribution in superconducting cable-in-conduit conductors \ud

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    Besides the temperature and magnetic field, the strain and stress state of the superconducting Nb3Sn wires in multi-stage twisted cable-in-conduit conductors (CICCs), as applied in ITER or high field magnets, strongly influence their transport properties. For an accurate quantitative prediction of the performance and a proper understanding of the underlying phenomena, a detailed analysis of the strain distribution along all individual wires is required. For this, the thermal contraction of the different components and the huge electromagnetic forces imposing bending and contact deformation must be taken into account, following the complex strand pattern and mutual interaction by contacts from surrounding strands. In this paper, we describe a numerical model for a superconducting cable, which can simulate the strain and stress states of all single wires including interstrand contact force and associated deformation. The strands in the cable can be all similar (Nb3Sn/Cu) or with the inclusion of different strand materials for protection (Cu, Glidcop).\ud \ud The simulation results are essential for the analysis and conductor design optimization from cabling to final magnet operation conditions. Comparisons are presented concerning the influence of the sequential cable twist pitches and the inclusion of copper strands on the mechanical properties and thus on the eventual strain distribution in the Nb3Sn filaments when subjected to electromagnetic forces, axial force and twist moment. Recommendations are given for conductor design improvements. \ud \ud \u

    Down or Out: Assessing the Welfare Costs of Household Investment Mistakes

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    This paper investigates the efficiency of household investment decisions in a unique dataset containing the disaggregated wealth and income of the entire population of Sweden. The analysis focuses on two main sources of inefficiency in the financial portfolio: underdiversification of risky assets ("down") and nonparticipation in risky asset markets ("out"). We find that while a few households are very poorly diversified, the cost of diversification mistakes is quite modest for most of the population. For instance, a majority of participating Swedish households are sufficiently diversified internationally to outperform the Sharpe ratio of their domestic stock market. We document that households with greater financial sophistication tend to invest more efficiently but also more aggressively, so the welfare cost of portfolio inefficiency tends to be greater for these households. The welfare cost of nonparticipation is smaller by almost one half when we take account of the fact that nonparticipants would be unlikely to invest efficiently if they participated in risky asset markets.

    Metformin induces distinct bioenergetic and metabolic profiles in sensitive versus resistant high grade serous ovarian cancer and normal fallopian tube secretory epithelial cells.

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    Metformin is a widely used agent for the treatment of diabetes and infertility, however, it has been found to have anti-cancer effects in a variety of malignancies including high grade serous ovarian cancer (HGSC). Studies describing the mechanisms by which metformin affects HGSC are ongoing, but detailed analysis of its effect on the cellular metabolism of both HGSC cells and their precursor, normal fallopian tube secretory epithelial cells (FTSECs), is lacking. We addressed the effects of metformin and the more potent biguanide, phenformin, on HGSC cell lines and normal immortalized FTSECs. Cell proliferation assays identified that FTSECs and a subset of HGSC cell lines are relatively resistant to the anti-proliferative effects of metformin. Bioenergetic and metabolomic analyses were used to metabolically differentiate the metformin-sensitive and metformin-resistant cell lines. Bioenergetically, biguanides elicited a significant decrease in mitochondrial respiration in all HGSC cells and FTSECs. However, biguanides had a greater effect on mitochondrial respiration in metformin sensitive cells. Metabolomic analysis revealed that metformin and phenformin generally induce similar changes in metabolic profiles. Biguanide treatment led to a significant increase in NADH in FTSECs and HGSC cells. Interestingly, biguanide treatment induced changes in the levels of mitochondrial shuttle metabolites, glycerol-3-phopshate (G3P) and aspartate, specifically in HGSC cell lines and not in FTSECs. Greater alterations in G3P or aspartate levels were also found in metformin sensitive cells relative to metformin resistant cells. These data identify bioenergetic and HGSC-specific metabolic effects that correlate with metformin sensitivity and novel metabolic avenues for possible therapeutic intervention

    The various manifestations of collisionless dissipation in wave propagation

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    The propagation of an electrostatic wave packet inside a collisionless and initially Maxwellian plasma is always dissipative because of the irreversible acceleration of the electrons by the wave. Then, in the linear regime, the wave packet is Landau damped, so that in the reference frame moving at the group velocity, the wave amplitude decays exponentially with time. In the nonlinear regime, once phase mixing has occurred and when the electron motion is nearly adiabatic, the damping rate is strongly reduced compared to the Landau one, so that the wave amplitude remains nearly constant along the characteristics. Yet, we show here that the electrons are still globally accelerated by the wave packet, and, in one dimension, this leads to a non local amplitude dependence of the group velocity. As a result, a freely propagating wave packet would shrink, and, therefore, so would its total energy. In more than one dimension, not only does the magnitude of the group velocity nonlinearly vary, but also its direction. In the weakly nonlinear regime, when the collisionless damping rate is still significant compared to its linear value, this leads to an effective defocussing effect which we quantify, and which we compare to the self-focussing induced by wave front bowing.Comment: 23 pages, 6 figure

    Puesta en valor de colecciones paleontológicas: designación de un lectotipo para Conohyus simorrensis (Lartet, 1851), Villefranche d'Astarac (Francia) y descripción de un nuevo género de tetraconodonto

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    The type species of the suid genus Conohyus Pilgrim (1925) is Sus simorrensis Lartet (1851) by original designation, but, as was usual at the time of the creation of the species in 1851, no holotype was nominated. Allusion was made by Lartet (1851) to upper and lower canines and some molars from two localities, Simorre and Villefranche d’Astarac, France. The canines belong to Listriodon splendens, a highly lophodont suid, but the molars were described as being bunodont. Until now a lectotype has not been nominated, partly because the original collections of Lartet (1851) were thought to be lost, but also because the diagnosis of the molars as bunodont was insufficient for distinguishing the species from a host of other suids. A suggestion was made to nominate a mandible from Le Fousseret as lectotype, but it was never formalised, and later it was proposed that a bunodont tooth from Simorre collected during the 1960s should be selected, but none was nominated. We here report the re-discovery of the collection of suids examined by Lartet (1851) and select a lectotype for the species Sus simorrensis. We provide detailed descriptions and illustrations of all the tetraconodont material from Villefranche d’Astarac, Simorre (Rajegats) and Le Fousseret, and discuss the relationships of the fossils to other tetraconodont samples from Europe. There are two taxa of bunodont tetraconodonts at Villefranche d’Astarac and Simorre, one of which represents a new genus, which is defined and described.Por designación original, la especie tipo del género de suidos Conohyus Pilgrim (1925) es Sus simorrensis Lartet (1851), pero como era habitual en el momento de la creación de la especie en 1851, no se designó el holotipo. Lartet (1851) aludió a los caninos superiores e inferiores y algunos molares de dos localidades: Simorre y Villefranche d'Astarac, Francia. Los caninos pertenecen a splendens Listriodon, un suido extremadamente lofodonto, pero los molares se describieron como bunodontos. Hasta ahora no se ha designado el lectotipo, en parte porque se pensaba que las colecciones originales de Lartet (1851) se habían perdido, pero también porque el diagnóstico de los molares como bunodontos era insuficiente para distinguir la especie a partir de una serie de otros suidos. Aunque se propuso nominar una mandíbula de Le Fousseret como lectotipo, nunca se formalizó, y más tarde se propuso que debía seleccionarse un diente bunodonto del Simorre obtenido durante la década de 1960, pero tampoco fue designado. En este trabajo se reporta el re-descubrimiento de la colección de suidos examinados por Lartet (1851) y se selecciona un lectotipo para la especie Sus simorrensis. Ofrecemos descripciones deta-lladas e ilustraciones de todo el material tetraconodonto de Villefranche d'Astarac, Simorre (Rajegats) y Le Fousseret, y se discuten las relaciones de los fósiles con otras muestras de tetraconodontos de Europa. Hay dos taxones de tetraconodontos bunodontos en Villefranche d' Astarac y Simorre , uno de los cuales representa un nuevo género, que se define y describe

    Kinetic modelling of runaway electron avalanches in tokamak plasmas

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    Runaway electrons (REs) can be generated in tokamak plasmas if the accelerating force from the toroidal electric field exceeds the collisional drag force due to Coulomb collisions with the background plasma. In ITER, disruptions are expected to generate REs mainly through knock-on collisions, where enough momentum can be transferred from existing runaways to slow electrons to transport the latter beyond a critical momentum, setting off an avalanche of REs. Since knock-on runaways are usually scattered off with a significant perpendicular component of the momentum with respect to the local magnetic field direction, these particles are highly magnetized. Consequently, the momentum dynamics require a full 3-D kinetic description, since these electrons are highly sensitive to the magnetic non-uniformity of a toroidal configuration. A bounce-averaged knock-on source term is derived. The generation of REs from the combined effect of Dreicer mechanism and knock-on collision process is studied with the code LUKE, a solver of the 3-D linearized bounce-averaged relativistic electron Fokker-Planck equation, through the calculation of the response of the electron distribution function to a constant parallel electric field. This work shows that the avalanche effect can be important even in non-disruptive scenarios. RE formation through knock-on collisions is found to be strongly reduced when taking place off the magnetic axis, since trapped electrons cannot contribute to the RE population. The relative importance of the avalanche mechanism is investigated as a function of the key parameters for RE formation; the plasma temperature and the electric field strength. In agreement with theoretical predictions, the simulations show that in low temperature and E-field knock-on collisions are the dominant source of REs and can play a significant role for RE generation, including in non-disruptive scenarios.Comment: 23 pages, 12 figure
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