6,195 research outputs found
Colonial Origins of Inequality in Hispanic America? Some reflections based on new empirical evidence
This paper attempts at contributing to the ongoing debate on the historical roots of the high economic inequality of contemporary Iberian America. Basically empirical, our approach departs from mainstream scholarship. We show new data on wages and heights in several viceroyalties that: 1) suggest relatively medium to high levels of material welfare among the commoners in Bourbon Hispanic America; 2) allow us to build indexes of economic inequality. An international comparison of those indexes casts some doubts on the widely accepted view that Viceroyal America’s economy was exclusively based on extremely unequal or extractive institutions, as it has been popularized by the influential works by Engerman and Sokoloff (1994, 2002, 2005), Acemoglu et al. (2002).economic inequality, Iberian America, Viceroyal America’s economy
Upper-Plate Earthquake Swarms Remotely Triggered by the 2012 Mw-7.6 Nicoya Earthquake, Costa Rica
Thirty Femtograms Detection of Iron in Mammalian Cells
Inorganic nanomaterials and particles with enhanced optical, mechanical or
magnetic attributes are currently being developed for a wide range of
applications. Safety issues have been formulated however concerning their
potential cyto- and genotoxicity. For in vivo and in vitro experimentations,
recent developments have heightened the need of simple and facile methods to
measure the amount of nanoparticles taken up by cells or tissues. In this work,
we present a rapid and highly sensitive method for quantifying the uptake of
iron oxide nanoparticles in mammalian cells. Our approach exploits the
digestion of incubated cells with concentrated hydrochloric acid reactant and a
colorimetric based UV-Visible absorption technique. The technique allows the
detection of iron in cells over 4 decades in masses, from 0.03 to 300 picograms
per cell. Applied on particles of different surface chemistry and sizes, the
protocol demonstrates that the coating is the key parameter in the
nanoparticle/cell interactions. The data are corroborated by scanning and
transmission electron microscopy and stress the importance of resiliently
adsorbed nanoparticles at the plasma membrane.Comment: 18 pages, 6 figure
Volatility and dividend risk in perpetual American options
American options are financial instruments that can be exercised at any time
before expiration. In this paper we study the problem of pricing this kind of
derivatives within a framework in which some of the properties --volatility and
dividend policy-- of the underlaying stock can change at a random instant of
time, but in such a way that we can forecast their final values. Under this
assumption we can model actual market conditions because some of the most
relevant facts that may potentially affect a firm will entail sharp predictable
effects. We will analyse the consequences of this potential risk on perpetual
American derivatives, a topic connected with a wide class of recurrent problems
in physics: holders of American options must look for the fair price and the
optimal exercise strategy at once, a typical question of free absorbing
boundaries. We present explicit solutions to the most common contract
specifications and derive analytical expressions concerning the mean and higher
moments of the exercise time.Comment: 21 pages, 5 figures, iopart, submitted for publication; deep
revision, two new appendice
Exit times in non-Markovian drifting continuous-time random walk processes
By appealing to renewal theory we determine the equations that the mean exit
time of a continuous-time random walk with drift satisfies both when the
present coincides with a jump instant or when it does not. Particular attention
is paid to the corrections ensuing from the non-Markovian nature of the
process. We show that when drift and jumps have the same sign the relevant
integral equations can be solved in closed form. The case when holding times
have the classical Erlang distribution is considered in detail.Comment: 9 pages, 3 color plots, two-column revtex 4; new Appendix and
references adde
Hydrodynamic Character of the Non-equipartition of Kinetic Energy in Binary Granular Gases
The influence of the heating mechanism on the kinetic energy densities of the
components of a vibrated granular mixture is investigated. Collisions of the
particles with the vibrating wall are inelastic and characterized by two
coefficients of normal restitution, one for each of the two species. By means
of molecular dynamics simulations, it is shown that the non-equipartition of
kinetic energy is not affected by the differential mechanism of energy
injection, aside the usual boundary layer around the wall. The macroscopic
state of the mixture in the bulk is defined by intensive variables that do not
include the partial granular temperatures of the components
In vitro toxicity of nanoceria: effect of coating and stability in biofluids
Due to the increasing use of nanometric cerium oxide in applications,
concerns about the toxicity of these particles have been raised and have
resulted in a large number of investigations. We report here on the
interactions between 7 nm anionically charged cerium oxide particles and living
mammalian cells. By a modification of the particle coating including
low-molecular weight ligands and polymers, two generic behaviors are compared:
particles coated with citrate ions that precipitate in biofluids and particles
coated with poly(acrylic acid) that are stable and remain nanometric. We find
that nanoceria covered with both coating agents are taken up by mouse
fibroblasts and localized into membrane-bound compartments. However, flow
cytometry and electron microscopy reveal that as a result of their
precipitation, citrate-coated particles interact more strongly with cells. At
cerium concentration above 1 mM, only citrate-coated nanoceria (and not
particles coated with poly(acrylic acid)) display toxicity and moderate
genotoxicity. The results demonstrate that the control of the surface chemistry
of the particles and its ability to prevent aggregation can affect the toxicity
of nanomaterials.Comment: 33 pages 10 figures, accepted at Nanotoxicolog
Congreso Avemariano de Granada [Música imrpesa]: del 3 al 9 de junio de 1940
En la cub.: Cincuentenario de las Escuelas del Ave MaríaEn la cub.: Obsequio de El Magisterio EspañolCopia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2012-2013Contiene: Ave María popular. Himno a las Escuelas del Ave María en su cincuentenario / letra de Tomás H. Redondo; música de José Monter
Charginos and Neutralinos Production at 3-3-1 Supersymmetric Model in Scattering
The goal of this article is to derive the Feynman rules involving charginos,
neutralinos, double charged gauge bosons and sleptons in a 3-3-1 supersymmetric
model. Using these Feynman rules we will calculate the production of a double
charged chargino with a neutralino and also the production of a pair of single
charged charginos, both in an electron- electron process.Comment: 18 pages, 8 figures, 2 table
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