Recientes tendencias en la teoría de la educación comparada

Antes de realizar la descripción de las actuales tendencias en la teoría de la Educación Comparada, se recuerdan las etapas a través de las cuales ha llegado a su estado actual. De esta manera se mencionan los periodos que Kazamias, Bereday, Noah y Eckstein han indicado en el desarrollo de la Educación Comparada, concluyendo con las que han indicado Kelly y Altbach. El autor no se muestra conforme con esta costumbre de diferenciar etapas pues cree que la evolución de la Educación Comparada ha sido efecto, más de unas doctrinas epistemológicas concretas que de unos movimientos globales. A continuación describe las tres principales de estas doctrinas, que han marcado unas tendencias en el modo de concebir y realizar la Educación Comparada. 1ª El pensamiento neopositivista busca una explicación funcional de la realidad, tratando de descubrir las leyes que explican sus fenómenos. Durkheim aplico este modo de ver a la Sociología, y Anderson lo ha hecho a la Educación Comparada. Se trata de aislar distintas variables y de descubrir las relaciones constantes que unen unas a otras. Dentro de esta línea Anderson utiliza el método hologeístico, que mide las variables teóricas en amplias muestras (de alcance mundial) de culturas humanas. Se puede aplicar este método también a la educación, como ha hecho Zern, defendiendo la idea de que la buena educación supone exigir al niño un esfuerzo y una sumisión disciplinada, lo cua1 mejora su socialización y su rendimiento intelectual. La investigación hologeística ha sido poco explotada y, si se superan las dificultades metodológicas que le son propias, promete llegar a ser el instrumento positivista más importante en Educación Comparada. 2ª E1 neomarxismo se halla presente también en los enfoques de la Educación Comparada, aportando las mismas ideas que va repitiendo en todas partes: que en los países capitalistas la educación está dirigida por una minoría privilegiada que busca, a través de ella, establecer la división de clases y explotar a los trabajadores. El principal representante de esta tendencia es Carnoy; algunos, como Wallert, pretenden que los análisis han de hacerse a nivel no nacional, sino mundial. 3º El neorrelativismo está representado por Brian Holmes. Desconfiando del concepto de medición absoluta y de la validez incondicional de leyes generales, y afirmando la relatividad de las Ciencias Naturales, se pretende una mera aproximación al "problema". Según esto, las Ciencias Sociales y la Educación Comparada han de abandonar la investigación pura y realizar una búsqueda de generalizaciones contextuales que ayuden a resolver los problemas prácticos. También están en esta línea los autores pertenecientes a la "nueva Sociología de la Educación" y a la etnometodología. Una realidad que esta tendencia no puede explicar son ciertas necesidades y exigencias humanas que revelan una tendencia invariable y universal, en lo más profundo de la persona humana.Before carrying out the description of the actual tendencies in the theory of Comparative Education the steps by which it has arrived at its present state should be remembered. The periods that Kazamias, Bereday, Noah and Eckstein have pointed out in the development of Comparative Education are mentioned concluding with those suggested by Kelly and Altbach. The author does not agree with this custom of distinguishing phases, he thinks that the evolution of Comparative Education has been effected more by concrete epistemological doctrines which have effected some tendencies in the way of conceiving and putting Comparative Education into effect. 1 Neopositivism looks for a functional explanation of reality, trying to discover the laws which explain its phenomenons. Durkheim applied this view to Sociology and Anderson has done so to Comparative Education. He tries to isolate distinct variables and to discover the constant relations that unite some to others. Within this framework Anderson utilises the hologeistic method which measures theoretical variables in worldwide samples of human cultures. This method can also be applied to education, as Zern has done, defending the idea that a good education requires the obedience and discipline of the child, which should improve its socialization and intellectual achievement. Hologeistic research has barely been tapped. If the methodological difficulties inherent in the approah can be overcome it promises to become the most important tool in Comparative Education. 2 Neomarxism is also an approach to Comparative Education with the same ideas that are being repeated everywhere: that in capitalist countries education is controlled by a privileged minority who seek by means of it to establish the division of classes and exploit the workers. The principal exponent of this theory is Carnoy; others like Wallert state that analysis has to be made at a national level. 3. Neorelativzsm is represented by B. Holmes. Distrusting the concept of absolute measurement and the unconditional validity of general laws and affirming the relationship of the Natural Sciences, it achieves a mere approximation to the problem. According to this the Social Sciences and Comparative Education have to give up pure research and carry out a search for contextual generalisations that would help to resolve the practical problems. The authorities of the new Sociology of education and tnomethodology are also following this line. This trend is not able to explain certain human necessities and requirements which reveal an invariable and universal tendency at the deepest leve

La enseñanza del idioma y el status político de Puerto Rico: una nueva evaluación.

Resumen en español.Resumen en inglés

Spintronics: Fundamentals and applications

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes from the published versio

Fluxes of biogenic components from sediment trap deployment in circumpolar waters of the Drake Passage

Circumpolar surface waters dominate the circulation of the Southern Ocean and sustain one of the ocean's largest standing stocks of biomass thereby producing a significant output of biogenic components, mainly diatoms, to the bottom sediments. Generally transit of biogenic matter from the sea surface to the sea floor affects nutrient regeneration fuels benthic life and transfers signals to the sediment record1–5. Reliable quantification of the relationship between biological production, fractionation of skeletal and tissue components and bottom sediment accumulation depends on direct vertical flux measurements from sediment trap deployments6–9, which have proved to be most scientifically productive10–13. We now present data on vertical mass fluxes from the Southern Ocean and evidence for strong biogeochemical fractionation between organic carbon-, nitrogen- and phosphorus-containing compounds, siliceous and calcareous skeletal remains, and refractory aluminosilicates

School Effects on the Wellbeing of Children and Adolescents

Well-being is a multidimensional construct, with psychological, physical and social components. As theoretical basis to help understand this concept and how it relates to school, we propose the Self-Determination Theory, which contends that self-determined motivation and personality integration, growth and well-being are dependent on a healthy balance of three innate psychological needs of autonomy, relatedness and competence. Thus, current indicators involve school effects on children’s well-being, in many diverse modalities which have been explored. Some are described in this chapter, mainly: the importance of peer relationships; the benefits of friendship; the effects of schools in conjunction with some forms of family influence; the school climate in terms of safety and physical ecology; the relevance of the teacher input; the school goal structure and the implementation of cooperative learning. All these parameters have an influence in promoting optimal functioning among children and increasing their well-being by meeting the above mentioned needs. The empirical support for the importance of schools indicates significant small effects, which often translate into important real-life effects as it is admitted at present. The conclusion is that schools do make a difference in children’s peer relationships and well-being

Semiconductor Spintronics

Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin or magnetism. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin injection, Silsbee-Johnson spin-charge coupling, and spindependent tunneling, as well as spin relaxation and spin dynamics. The most fundamental spin-dependent nteraction in nonmagnetic semiconductors is spin-orbit coupling. Depending on the crystal symmetries of the material, as well as on the structural properties of semiconductor based heterostructures, the spin-orbit coupling takes on different functional forms, giving a nice playground of effective spin-orbit Hamiltonians. The effective Hamiltonians for the most relevant classes of materials and heterostructures are derived here from realistic electronic band structure descriptions. Most semiconductor device systems are still theoretical concepts, waiting for experimental demonstrations. A review of selected proposed, and a few demonstrated devices is presented, with detailed description of two important classes: magnetic resonant tunnel structures and bipolar magnetic diodes and transistors. In most cases the presentation is of tutorial style, introducing the essential theoretical formalism at an accessible level, with case-study-like illustrations of actual experimental results, as well as with brief reviews of relevant recent achievements in the field.Comment: tutorial review; 342 pages, 132 figure

Association of the PHACTR1/EDN1 genetic locus with spontaneous coronary artery dissection

Background: Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndromes (ACS) afflicting predominantly younger to middle-aged women. Observational studies have reported a high prevalence of extracoronary vascular anomalies, especially fibromuscular dysplasia (FMD) and a low prevalence of coincidental cases of atherosclerosis. PHACTR1/EDN1 is a genetic risk locus for several vascular diseases, including FMD and coronary artery disease, with the putative causal noncoding variant at the rs9349379 locus acting as a potential enhancer for the endothelin-1 (EDN1) gene. Objectives: This study sought to test the association between the rs9349379 genotype and SCAD. Methods: Results from case control studies from France, United Kingdom, United States, and Australia were analyzed to test the association with SCAD risk, including age at first event, pregnancy-associated SCAD (P-SCAD), and recurrent SCAD. Results: The previously reported risk allele for FMD (rs9349379-A) was associated with a higher risk of SCAD in all studies. In a meta-analysis of 1,055 SCAD patients and 7,190 controls, the odds ratio (OR) was 1.67 (95% confidence interval [CI]: 1.50 to 1.86) per copy of rs9349379-A. In a subset of 491 SCAD patients, the OR estimate was found to be higher for the association with SCAD in patients without FMD (OR: 1.89; 95% CI: 1.53 to 2.33) than in SCAD cases with FMD (OR: 1.60; 95% CI: 1.28 to 1.99). There was no effect of genotype on age at first event, P-SCAD, or recurrence. Conclusions: The first genetic risk factor for SCAD was identified in the largest study conducted to date for this condition. This genetic link may contribute to the clinical overlap between SCAD and FMD

Virtual Ontogeny of Cortical Growth Preceding Mental Illness

Background: Morphology of the human cerebral cortex differs across psychiatric disorders, with neurobiology and developmental origins mostly undetermined. Deviations in the tangential growth of the cerebral cortex during pre/perinatal periods may be reflected in individual variations in cortical surface area later in life. Methods: Interregional profiles of group differences in surface area between cases and controls were generated using T1-weighted magnetic resonance imaging from 27,359 individuals including those with attention-deficit/hyperactivity disorder, autism spectrum disorder, bipolar disorder, major depressive disorder, schizophrenia, and high general psychopathology (through the Child Behavior Checklist). Similarity of interregional profiles of group differences in surface area and prenatal cell-specific gene expression was assessed. Results: Across the 11 cortical regions, group differences in cortical area for attention-deficit/hyperactivity disorder, schizophrenia, and Child Behavior Checklist were dominant in multimodal association cortices. The same interregional profiles were also associated with interregional profiles of (prenatal) gene expression specific to proliferative cells, namely radial glia and intermediate progenitor cells (greater expression, larger difference), as well as differentiated cells, namely excitatory neurons and endothelial and mural cells (greater expression, smaller difference). Finally, these cell types were implicated in known pre/perinatal risk factors for psychosis. Genes coexpressed with radial glia were enriched with genes implicated in congenital abnormalities, birth weight, hypoxia, and starvation. Genes coexpressed with endothelial and mural genes were enriched with genes associated with maternal hypertension and preterm birth. Conclusions: Our findings support a neurodevelopmental model of vulnerability to mental illness whereby prenatal risk factors acting through cell-specific processes lead to deviations from typical brain development during pregnancy

Genetic associations at 53 loci highlight cell types and biological pathways relevant for kidney function.

Reduced glomerular filtration rate defines chronic kidney disease and is associated with cardiovascular and all-cause mortality. We conducted a meta-analysis of genome-wide association studies for estimated glomerular filtration rate (eGFR), combining data across 133,413 individuals with replication in up to 42,166 individuals. We identify 24 new and confirm 29 previously identified loci. Of these 53 loci, 19 associate with eGFR among individuals with diabetes. Using bioinformatics, we show that identified genes at eGFR loci are enriched for expression in kidney tissues and in pathways relevant for kidney development and transmembrane transporter activity, kidney structure, and regulation of glucose metabolism. Chromatin state mapping and DNase I hypersensitivity analyses across adult tissues demonstrate preferential mapping of associated variants to regulatory regions in kidney but not extra-renal tissues. These findings suggest that genetic determinants of eGFR are mediated largely through direct effects within the kidney and highlight important cell types and biological pathways