2,888 research outputs found
Inequality aversion among Spanish gypsies: an experimental approach [Aversión a la desigualdad entre gitanos Españoles: un enfoque experimental]
This paper presents a first attempt to measure inequality aversion among gypsies. We conducted an experiment among adult gypsies living at slums outside Vallecas (Madrid). To analyze this variable we use the mechanism provided by Kroll & Davidovitz (2003) among 38 voluntary participants. Results indicate that: i) 52.6% of the individuals are inequality averse; ii) there is a positive relationship between inequality aversion and some features of the population such as individual religious practice, marital status, family size, position in the hierarchy of the family or club association and, iii) neither wealth, nor participation in voluntary activities affect inequality aversion
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Electronic properties of SnO2-based ceramics with double function of varistor and humidity sensor
This is the post-print version of the article. The official published version can be obtained from the link below - Copyright @ 2010 AD-Tech.Tin dioxide based varistor ceramics SnO2-Co3O4-Nb2O5-Cr2O3-xCuO (x=0; 0.05; 0.1 and 0.5) were made and their electrical properties were studied. The highest nonlinearity coefficient and electric field (at current density 10-3 A cm-2) were obtained for 0.1 mol.% CuO addition. It was observed that low-field electrical conductivity is increased with relative humidity, therefore, materials obtained exhibit double function of varistor and humidity sensor. The highest humidity sensitivity coefficient is found for SnO2-Co3O4-Nb2O5-Cr2O3 ceramics (without CuO). Observed varistor and humidity-sensitive properties are explained in the frames of grain-boundary double Schottky barrier concept as a decrease of the barrier height with electric field or relative humidity. Using suggested simple theory and data obtained on isothermal capacitance relaxation, the energy of the grain-boundary monoenergetic trapping states were estimated. These values are less than found for activation energy of electrical conduction (as a measure of the barrier height). These observations confirm the barrier concept.This work is funded by the Royal Society, United Kingdom (2007R1/R26999)
Reliability of P mode event classification using contemporaneous BiSON and GOLF observations
We carried out a comparison of the signals seen in contemporaneous BiSON and
GOLF data sets. Both instruments perform Doppler shift velocity measurements in
integrated sunlight, although BiSON perform measurements from the two wings of
potassium absorption line and GOLF from one wing of the NaD1 line.
Discrepancies between the two datasets have been observed. We show,in fact,
that the relative power depends on the wing in which GOLF data observes. During
the blue wing period, the relative power is much higher than in BiSON datasets,
while a good agreement has been observed during the red period.Comment: 7 pages, HELAS II: Helioseismology, Asteroseismology, and MHD
Connections, conference proceedin
Genetic Characterization of Jaguars (Panthera onca) in Captivity in Zoological Parks of Colombia
The construction of the pedigree of captive jaguars (Panthera onca) in zoological parks of Colombia was done using the analysis of the Regional Studbook for Jaguars and DNA analysis of 9 microsatellites of 20 Jaguars (n=20). The assignments for paternities and maternities were done with for the program CERVUS and the relationship between animals were established with the KINSHIP program. The analysis of the Studbook was done with SPARKS and PM2000 software generating the following values: genetic diversity for the population (GD=0.7832), potential genetic diversity (GD=0.9113), genic value (GV=0.7846), mean coefficient of inbreeding (F=0.0179), and the Mean KINSHIP (MK) for each individual. The averages of the observed and expected heterozygosity were 0.687 and 0.684 respectively. Nevertheless, a wild jaguar sample of 156 individuals obtained in Colombia substantially showed a higher degree of gene diversity (H = 0.87) than the Colombian captive jaguar population. Thus, the captive jaguar population retained 78 % of the gene diversity of the Colombian wild jaguar population. With this study the pedigree of the captive population of jaguars was built in order to develop an ex situ conservation plan for the species in the Colombian zoological parks
Equilibrium and kinetic studies on complex formation and decomposition and the movement of Cu2+metal ions within polytopic receptors
Potentiometric studies carried out on the interaction of two tritopic double-scorpiand receptors in which two equivalent 5-(2-aminoethyl)-2,5,8-triaza[9]-(2,6)-pyridinophane moieties are linked with 2,9- dimethylphenanthroline (L1) and 2,6-dimethylpyridine (L2) establish the formation of mono-, bi- and trinuclear Cu2+ complexes. The values of the stability constants and paramagnetic 1H NMR studies permit one to infer the most likely coordination modes of the various complexes formed. Kinetic studies on complex formation and decomposition have also been carried out. Complex formation occurs with polyphasic kinetics for both receptors, although a significant difference is found between both ligands with respect to the relative values of the rate constants for the metal coordination steps and the structural
reorganizations following them. Complex decomposition occurs with two separate kinetic steps, the first one being so fast that it occurs within the stopped-flow mixing time, whereas the second one is slow enough to allow kinetic studies using a conventional spectrophotometer. As a whole, the kinetic experiments also provide information about the movement of the metal ion within the receptors. The differences observed between the different receptors can be interpreted in terms of changes in the network of hydrogen bonds formed in the different species
Changes in marine turbot (Scophthalmus maximus) epidermis and skin mucus composition during development from bilateral larvae to juvenile flat fish
Alike other flat fish, marine turbot has the particularity that changes from larvae with bilateral symmetry to adult with asymmetry, in terms of the position of the eyes. As expected, the skin configuration of this species is also affected by the development and transformation suffered by fish during metamorphosis. In this context, changes in the epidermis of marine turbot were studied using conventional staining and histochemical techniques using six lectins (UEA-I, PNA, RCA-I, WGA, Con A and SBA). During development from larvae to juvenile (3â300âdays post-hatching), the epidermis increased in both thickness and the number of cell layers. In fact, the simple cuboidal epithelium observed in larvae at day 3 already became stratified at days 10â12, which sequentially increase in thickness with fish development. Turbot epidermis is composed basically of four cell types: epithelial and mucous or secretory cells that are present through the development, and pigmented cells and a type that the authors described as club-like cells that appear during and post-metamorphosis. The Alcian blue-periodic acid Schiff (AB-PAS) histochemical method revealed the presence of neutral glycoconjugates in mucous and club-like cells at post-metamorphic stages of fish. Accordingly, lectin analysis showed mucous cells containing glycoproteins rich in fucose (UEA-I labelling) and glycoconjugates rich in the sequence galactose-N-acetyl galactosamine (PNA and RCA-I labelling) when this cell type appears. Interestingly, melanophores were observed in the dorsal epidermis of post-metamorphic juveniles. This type of cell contains a black-to-brown pigment that provides the skin the typical colour of this fish species. Changes in mucous coat composition were observed during fish development, which was attributed to different roles of the glycoconjugates.Ministerio de Ciencia e InnovaciĂłn | Ref. CGL 2009-07904Universidade de Vigo/ CISU
ÂżCĂłmo articulamos la evaluaciĂłn como sistema desde una perspectiva compleja en el marco de la sostenibilidad curricular?
La evaluaciĂłn adquiere un papel determinante en el desarrollo de competencias para la sostenibilidad del alumnado, por lo que hay que ser consecuente con su diseño y aplicaciĂłn. Hay que caracterizar los aspectos del sistema de evaluaciĂłn y, por encima de ello, permitir que el sistema se comporte como tal, priorizando relaciones entre elementos. Partimos de una revisiĂłn teĂłrica y un posterior anĂĄlisis del sistema de evaluaciĂłn diseñados e implementados por profesores comprometidos con la sostenibilidad. La idea es enriquecer la imagen conformada teĂłricamente con los aspectos derivados de la integraciĂłn prĂĄctica, desde una perspectiva compleja. La interacciĂłn entre ambas informaciones aporta un nuevo enfoque de la evaluaciĂłn. Hemos optado por la TeorĂa Fundamentada -TF-, como estrategia de anĂĄlisis; lo cual que nos ha permitido esbozar el Modelo Final
Fibrohistiocitoma maligno Ăłseo tras degeneraciĂłn de enfermedad de Paget Caso clĂnico y revisiĂłn de la literatura
El fibrohistiocitoma maligno Ăłseo es un tumor de estirpe mesenquimal poco frecuente,
pero de alta agresividad. Se suele presentar de forma primaria, aunque a veces lo hace sobre
lesiones previas en el hueso. Puede ser difĂcil de diferenciar histolĂłgicamente de otros tumores,
pero es una entidad propia desde el punto de vista anatomopatolĂłgico. Presentamos un paciente
con enfermedad de Paget que desarrolló un fibrohistiocitoma maligno óseo en el fémur
sobre el hueso pagético. Fue tratado mediante desarticulación de cadera. No se usó quimioterapia
como tratamiento coadyuvante debido a su avanzada edad y situaciĂłn basal. A los 18 meses se
encuentra asintomĂĄtico y sin signos de recurrencia. Se hace una revisiĂłn de la literatura acerca
de este tumor.Malignant fibrous histiocytoma of bone is a rare but highly agressive mesenchimal
tumor. It usually arises as a primary tumor but sometimes it can be associated with pre-existing bone
abnormalities. Histologically it can be missdiagnosed with other tumors. We report a case of malignant
fibrous histiocytoma of bone in the femur in a patient with Paget's disease treated by hip
desarticulation. We didn't use chemotherapy because his elderly status. At 18 months follow up, the
patient is symptom-free and neither local recurrence nor metastasis have been found. A review of
the literature has been carried out
Post-glacial evolution of alpine environments in the western Mediterranean region : The Laguna Seca record
In an effort to understand how alpine environments from the western Mediterranean region responded to climate variations since the last glacial-interglacial transition, a detailed chronological control and sedimentological analysis, supported by magnetic susceptibility, total organic carbon and C/N data, were carried out on the sedimentary record of Laguna Seca (LS). This is a latitudinal and altitudinally (2259 masl) key alpine wetland site located in the easternmost area of the Sierra Nevada, southern Iberian Peninsula, where sediments accumulated during Heinrich Stadial 1, Bolling-Allerod (B-A) and the Younger Dryas (YD) previously unrecorded in alpine Sierra Nevada. Climate controlled sedimentation in LS and three coarse-grained and one fine-grained facies association are differentiated, which help us decipher the paleoenvironmental evolution of LS: (1) subaerial cohesionless debris flows during a paraglacial stage; (2) till or nival diamicton during a small glacier/nivation hollow stage; (3) massive mudstone by suspension settling of clays into standing water during a lacustrine stage; and (4) frost-shattering breccia deposited inside the lacustrine stage, probably during the YD, and linked to a periglacial substage. The development of a previously existing small glacial cirque during the Last Glacial Maximum (LGM) in the LS basin at an elevation between 2500 and 2300 m could be supported by the important availability of slope sediments glacially-conditioned such as debris flows, reworked by paraglacial slope processes during the first deglaciation stages, confirming previous studies of landforms in the catchment area and the LGM-Equilibrium Line Altitude estimation above 2400 masl in Sierra Nevada. Mean sediment accumulation rates in the LS sedimentary units (4.21 and 0.28 mm/yr during the paraglacial small glacier/nivation stage and the lacustrine stage, respectively) confirm that geomorphic activity accelerated just after glaciers retreated due to a slope adjustment and high availability of glacially conditioned sediments. An abrupt change in paleoenvironmental and paleoclimatic conditions occurred in LS at ~ 15.7 cal kyr BP. This change was probably due to an increase in temperature and precipitation in the western Mediterranean region during the B-A. At LS, this resulted in significant ice-melt, forming a deep-water lake in LS with important organic matter contribution until the end of the Early Holocene (except in the YD when the lake level probably dropped), but elsewhere a general glacier recession in the Sierra Nevada and an expansion of the Mediterranean forest in the southern Iberian Peninsula. Finally, the general long-term aridification that occurred during the Middle Holocene until the present in the western Mediterranean region triggered an important environmental change transforming LS into an ephemeral wetland with an increase in aquatic productivity.Peer reviewe
Solar cycle variations of large frequency separations of acoustic modes: Implications for asteroseismology
We have studied solar cycle changes in the large frequency separations that
can be observed in Birmingham Solar Oscillations Network (BiSON) data. The
large frequency separation is often one of the first outputs from asteroseismic
studies because it can help constrain stellar properties like mass and radius.
We have used three methods for estimating the large separations: use of
individual p-mode frequencies, computation of the autocorrelation of
frequency-power spectra, and computation of the power spectrum of the power
spectrum. The values of the large separations obtained by the different methods
are offset from each other and have differing sensitivities to the realization
noise. A simple model was used to predict solar cycle variations in the large
separations, indicating that the variations are due to the well-known solar
cycle changes to mode frequency. However, this model is only valid over a
restricted frequency range. We discuss the implications of these results for
asteroseismology.Comment: 9 pages, 11 figures, accepted for publication in MNRAS, references
updated, corrections following proof
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