340 research outputs found
Self-assembly of gold supraparticles with crystallographically aligned and strongly coupled nanoparticle building blocks for SERS and photothermal therapy
A new method is introduced for self-assembling citrate-capped gold nanoparticles into supraparticles with crystallographically aligned building blocks. It consists in confining gold nanoparticles inside a cellulos acetate membrane. The constituent nanoparticles are in close contact in the superstructure, and therefore generate hot spots leading to intense SERS signals. They also generate more plasmonic heat than the nanoparticle building blocks. The supraparticles are internalized by cells and show low cytotoxicity, but can kill cancer cells when irradiated with a laser. This, along with the improved plasmonic properties arising from their assembly, makes the gold supraparticles promising materials for applications in bioimaging and nanomedicine
TET-dependent regulation of retrotransposable elements in mouse embryonic stem cells.
BACKGROUND: Ten-eleven translocation (TET) enzymes oxidise DNA methylation as part of an active demethylation pathway. Despite extensive research into the role of TETs in genome regulation, little is known about their effect on transposable elements (TEs), which make up nearly half of the mouse and human genomes. Epigenetic mechanisms controlling TEs have the potential to affect their mobility and to drive the co-adoption of TEs for the benefit of the host. RESULTS: We performed a detailed investigation of the role of TET enzymes in the regulation of TEs in mouse embryonic stem cells (ESCs). We find that TET1 and TET2 bind multiple TE classes that harbour a variety of epigenetic signatures indicative of different functional roles. TETs co-bind with pluripotency factors to enhancer-like TEs that interact with highly expressed genes in ESCs whose expression is partly maintained by TET2-mediated DNA demethylation. TETs and 5-hydroxymethylcytosine (5hmC) are also strongly enriched at the 5' UTR of full-length, evolutionarily young LINE-1 elements, a pattern that is conserved in human ESCs. TETs drive LINE-1 demethylation, but surprisingly, LINE-1s are kept repressed through additional TET-dependent activities. We find that the SIN3A co-repressive complex binds to LINE-1s, ensuring their repression in a TET1-dependent manner. CONCLUSIONS: Our data implicate TET enzymes in the evolutionary dynamics of TEs, both in the context of exaptation processes and of retrotransposition control. The dual role of TET action on LINE-1s may reflect the evolutionary battle between TEs and the host
Las interprofesionales: una oportunidad para la organización del sistema agroalimentario
122 p. Series Agroalimentarias. Cuadernos de Organización (IICA) no. 2000-01.En este documento se destacan las características esenciales de un tipo de organizaciones de carácter vertical que ha tenido un importante papel en la vertebración del sistema agroalimentario de algunos países europeos en pasadas décadas. En la actualidad, este tipo de organización se perfila como el más adecuado para facilitar la adaptación de la pequeña y mediana empresa con una visión integral de la cadena producción-transformación, a las nuevas exigencias del mercado y el consumidor. (MV
Higher Education as modulator of gender inequalities: Evidence of the Spanish case
Raising educational levels may help to reduce inequalities between men and women in certain social and economic aspects. Using statistics for Spain, we analyse labour market behaviours such as the rates of activity and unemployment by sex according to the educational level. The results reveal that the differences between men and women decrease as the educational level increases. In particular, the modulator effect of education is very important at the higher level, where differences in labour market behaviour between men and women with an university education almost disappear, except in terms of salaries. Nevertheless, it can be seen that the current economic crisis has reduced the modulator role of education in gender differences in Spain
Fertility and economic instability: the role of unemployment and job displacement
In this paper, we study the separate effects of unemployment and job displacement on fertility in a sample of white collar women in Austria. Using an instrumental variable approach, we show that unemployment incidence as such has no negative effect on fertility decisions, but the very fact of being displaced from a career-oriented job has. Fertility rates for women affected by a firm closure are significantly below those of a control group, even after 6 years, and this is so irrespective of the incidence or the duration of the associated unemployment spell
The decisions of Spanish youth : a cross-section study
The original publication is available at www.springerlink.comThis paper presents a simultaneous model for the joint decisions of working, studying and leaving the parental household by young people in Spain. Using cross-section data from the 1990–1991 Encuesta de Presupuestos Familiares, the model is estimated by a two stage estimation method. Endogeneity of the three decisions proves to be important in order to understand the dynamics of household formation. Our results also confirm a number of plausible intuitions about the effect of individual characteristics and economic variables on these decisions, and provide some new insights into the reasons for young people in Spain remaining in large numbers in the parental home. Most of the results are gender independent.Publicad
O Mapa Geográfico de América Meridional, de Juan de la Cruz Cano y Olmedilla
This essay examines the history of the construction of the Mapa Geográfico de América Meridional (Map of South America) by Juan de la Cruz Cano y Olmedilla, how its various editions were engraved, as well as its circulation and reception during the second half of the 18th century in the light of the ongoing dispute between Portugal and Spain over the boundaries of Brazil
Social Security Coverage and the Labor Market in Developing Countries
This paper analyzes the reasons behind the low rates of contribution to social security programs in developing countries. Using a large set of harmonized household surveys from Latin America we compare contribution patterns among wage employees, for whom participation is compulsory, with contribution patterns among self-employed workers, for whom participation is often voluntary. In all countries, contribution rates among salaried workers are similarly correlated with education, earnings, size of the employer, household characteristics and age. In addition, contribution patterns among salaried workers are highly correlated with contribution patterns among the self-employed. Our results indicate that on average more than 30 percent of the explained within-country variance in contributions patterns may be accounted for by individuals low willingness to participate in old-age pension programs. Nonetheless, we also find evidence suggesting that some workers are rationed out of social security against their will
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