Causes of legume-rotation effects in increasing cereal yields across the Sudanian, Sahelian and Guinean zone of West Africa

On-farm experiments and pot trials were conducted on eight West African soils to explore the mechanisms governing the often reported legume rotation-induced cereal growth increases in this region. Crops comprised pearl millet (Pennisetum glaucum L.), sorghum (Sorghum bicolor Moench), maize (Zea mays L.), cowpea (Vigna unguiculata Walp.) and groundnut (Arachis hypogaea L.). In groundnut trials the observed 26 to 85% increases in total dry matter (TDM) of rotation cereals (RC) compared with continuous cereals (CC) in the 4th year appeared to be triggered by site- and crop-specific early season differences in nematode infestation (up to 6-fold lower in RC than in CC), enhanced Nmin and a 7% increase in mycorrhizal (AM) infection. In cowpea trials yield effects on millet and differences in nematode numbers, Nmin and AM were much smaller. Rhizosphere studies indicated effects on pH and acid phosphatase activity as secondary causes for the observed growth differences between RC and CC. In the study region legume-rotation effects on cereals seemed to depend on the capability of the legume to suppress nematodes and to enhance early N and P availability for the subsequent cereal.

Evaluating partial root-zone irrigation and mulching in okra (Abelmoschus esculentus L.) under a sub-humid tropical climate

The field experiments were conducted to compare the alternate partial root-zone irrigation (APRI) with and without black plastic mulch (BPM) with full root-zone irrigation (FRI) in furrow-irrigated okra (Abelmoschus esculentus L. Moench) at Bhubaneswar, India. APRI means that one of the two neighbouring furrows was alternately irrigated during consecutive watering. FRI was the conventional method where every furrow was irrigated during each watering. The used irrigation levels were 25% available soil moisture depletion (ASMD), 50% ASMD, and 75% ASMD. The plant growth and yield parameters were observed to be significantly (p < 0.05) higher with frequent irrigation (at 25% ASMD) under all irrigation strategies. However, APRI + BPM produced the maximum plant growth and yield using 22% and 56% less water over APRI without BPM and FRI, respectively. The highest pod yield (10025 kg ha^-1) was produced under APRI at 25% ASMD + BPM, which was statistically at par with the pod yield under APRI at 50% ASMD + BPM. Irrigation water use efficiency (IWUE), which indicates the pod yield per unit quantity of irrigation water, was estimated to be highest (12.3 kg m^-3) under APRI at 50% ASMD + BPM, followed by APRI at 25% ASMD + BPM. Moreover, the treatment APRI at 50% ASMD + BPM was found economically superior to other treatments, generating more net return (US $ 952 ha^-1) with higher benefit–cost ratio (1.70).

1.55 µm High-Speed QDs Lasers for Optical Telecommunication Applications

In this work investigation of the QDs formation and the fabrication of QD based semiconductor lasers for telecom applications are presented. InAs QDs grown on AlGaInAs lattice matched to InP substrates are used to fabricate lasers operating at 1.55 µm, which is the central wavelength for far distance data transmission. This wavelength is used due to its minimum attenuation in standard glass fibers. The incorporation of QDs in this material system is more complicated in comparison to InAs QDs in the GaAs system. Due to smaller lattice mismatch the formation of circular QDs, elongated QDs and quantum wires is possible. The influence of the different growth conditions, such as the growth temperature, beam equivalent pressure, amount of deposited material on the formation of the QDs is investigated. It was already demonstrated that the formation process of QDs can be changed by the arsenic species. The formation of more round shaped QDs was observed during the growth of QDs with As2, while for As4 dash-like QDs. In this work only As2 was used for the QD growth. Different growth parameters were investigated to optimize the optical properties, like photoluminescence linewidth, and to implement those QD ensembles into laser structures as active medium. By the implementation of those QDs into laser structures a full width at half maximum (FWHM) of 30 meV was achieved. Another part of the research includes the investigation of the influence of the layer design of lasers on its lasing properties. QD lasers were demonstrated with a modal gain of more than 10 cm-1 per QD layer. Another achievement is the large signal modulation with a maximum data rate of 15 Gbit/s. The implementation of optimized QDs in the laser structure allows to increase the modal gain up to 12 cm-1 per QD layer. A reduction of the waveguide layer thickness leads to a shorter transport time of the carriers into the active region and as a result a data rate up to 22 Gbit/s was achieved, which is so far the highest digital modulation rate obtained with any 1.55 µm QD laser. The implementation of etch stop layers into the laser structure provide the possibility to fabricate feedback gratings with well defined geometries for the realization of DFB lasers. These DFB lasers were fabricated by using a combination of dry and wet etching. Single mode operation at 1.55 µm with a high side mode suppression ratio of 50 dB was achieved.

Dairy farms typology and management of animal genetic resources in the peri-urban zone of Bamako (Mali)

Facing growth in demand, dairy production in peri-urban areas of developing countries is changing rapidly. To characterise this development around Bamako (Mali), this study establishes a typology of dairy production systems with a special focus on animal genetic resources. The survey included 52 dairy cattle farms from six peri-urban sites. It was conducted in 2011 through two visits, in the dry and harvest seasons. The median cattle number per farm was 17 (range 5-118) and 42% of farmers owned cropland (8.3 +/- 7.3 ha, minimum 1 ha, maximum 25 ha). Feeding strategy was a crucial variable in farm characterisation, accounting for about 85% of total expenses. The use of artificial insemination and a regular veterinary follow-up were other important parameters. According to breeders’ answers, thirty genetic profiles were identified, from local purebreds to different levels of crossbreds. Purebred animals raised were Fulani Zebu (45.8%), Maure Zebu (9.2%), Holstein (3.0%), Azawak Zebu (1.3%), Mere Zebu (0.5%) and Kuri taurine (0.1%). Holstein crossbred represented 30.5% of the total number of animals (19.0% Fulani-Holstein, 11.2% Maure-Holstein and 0.3% Kuri-Holstein). Montbéliarde, Normande and Limousin crossbreds were also found (6.6%, 0.7% and 0.3%, respectively). A multivariate analysis helped disaggregate the diversity of management practices. The high diversity of situations shows the need for consideration of typological characteristics for an appropriate intervention. Although strongly anchored on local breeds, the peri-urban dairy systems included a diversity of exotic cattle, showing an uncoordinated quest of breeders for innovation. Without a public intervention, this dynamic will result in an irremediable erosion of indigenous animal genetic resources.

Cognitive abilities, sociocultural background and academic achievement

Resumen tomado de la publicaci??n

Youth sport dropout from the achievement goal theory. 'El abandono del deporte en j??venes desde la Teor??a de las metas de logro'

Resumen tomado de la publicaci??n. Resumen tambi??n en ingl??s

Self-regulated profiles and academic achievement. 'Perfiles de aprendizaje autorregulado y rendimiento acad??mico'

Resumen tomado de la publicaci??n

Family background, adolescent's achievement and aspirations, and young adult's enrolment in Australian Universities

Resumen tomado de la publicaci??n

Achievement goals, social goals, and motivational regulations in physical education settings

Resumen tomado de la publicaci??n

Equality of educational opportunity employing Pisa data: taking both achievement and access into account

La medición de la desigualdad de oportunidades con las bases de PISA implican varias limitaciones: (i) la muestra sólo representa una fracción limitada de las cohortes de jóvenes de 15 años en los países en desarrollo y (ii) estas fracciones no son uniformes entre países ni entre periodos. Lo anterior genera dudas sobre la confiabilidad de estas mediciones cuando se usan para comparaciones internacionales: mayor equidad puede ser resultado de una muestra más restringida y más homogénea. A diferencia de enfoques previos basados en reconstrucción de las muestras, el enfoque del documento consiste en proveer un índice bidimensional que incluye logro y acceso como dimensiones del índice. Se utilizan varios métodos de agregación y se observan cambios considerables en los rankings de (in) equidad de oportunidades cuando solo se observa el logro y cuando se observan ambas dimensiones en las pruebas de PISA 2006/2009. Finalmente se propone una generalización del enfoque permitiendo otras dimensiones adicionales y otros pesos utilizados en la agregación.

Academic achievement in sciences: the role of preferences and educative assets

This paper provides new evidence on the effect of pupil’s self-motivation and academic assets allocation on the academic achievement in sciences across countries. By using the Programme for International Student Assessment 2006 (PISA 2006) test we find that both explanatory variables have a positive effect on student’s performance. Self-motivation is measured through an instrument that allows us to avoid possible endogeneity problems. Quantile regression is used for analyzing the existence of different estimated coefficients over the distribution. It is found that both variables have different effect on academic performance depending on the pupil’s score. These findings support the importance of designing focalized programs for different populations, especially in terms of access to information and communication technologies such as internet.

Inequality of opportunity in educational achievement in Latin America: evidence from PISA 2006-2009

We assess inequality of opportunity in educational achievement in six Latin American countries, employing two waves of PISA data (2006 and 2009). By means of a non-parametric approach using a decomposable inequality index, GE(0), we rank countries according to their degree of inequality of opportunity. We work with alternative characterizations of types: school type (public or private), gender, parental education, and combinations of those variables. We calculate incremental contributions of each set of circumstances to inequality. We provide rankings of countries based on unconditional inequalities (using conventional indices) and on conditional inequalities (EOp indices), and the two sets of rankings do not always coincide. Inequality of opportunities range from less than 1% to up to 27%, with substantial heterogeneity according to the year, the country, the subject and the specificication of circumstances. Robustness checks based on bootstrap and the use of an alternative index confirm most of the initial results.

Oxford maths zone. Year 3. Lesson plans with answers.

Este programa ofrece una gama flexible de recursos para cubrir todas las necesidades para la enseñanza de las matemáticas. Establece un plan coherente asegurando que se cumplan todos los objetivos de la estrategia Nacional de Cálculo. Contiene una amplia gama de modernos, dinámicos recursos para hace fácil la gestión del aula y muestran a los alumnos cómo usar las matemáticas en el mundo real. Presenta una programación de una semana, para cada semana del año y proporciona el marco fundamental en torno al cual se basan los otros recursos para proporcionar un conjunto coherente. Tiene estos rasgos principales; actividades mentales; enseñanza interactiva con la clase; actividad compartida de resolución de problemas.

Oxford maths zone. Year 3. Copymasters.

Proporciona una amplia gama de recursos fotocopiables de apoyo para acompañar a los tres años de Oxford Mhats Zone. Las páginas se pueden reproducir por aquellos que prefieren ofrecer estas actividades en una base adecuada. La segunda sección ofrece hojas de estímulo para todas las unidades. La tercera sección ofrece fotocopiables que están vinculadas específicamente unidad por unidad. la cuarta sección se ofrecen fotocopiables, en general, que pueden utilizarse en cualquier momento. la quinta sección contiene un conjunto fotocopiable que proporcionan una simple introducción a cada página del libro básico para los niños que requieren apoyo adicional.

Oxford maths zone. Year 3. Core book.

Contiene una amplia gama de recursos destinados a enseñar a los niños cómo usar las matemáticas en el mundo real, su pertinencia y relevancia; también ofrece orientación sobre las principales actividades para cada uno de los niveles. Cumple con los requisitos del National Numeracy Strategy en cuanto a los conocimientos básicos de aritmética que proporciona y a toda la secuencia de material didáctico que le acompaña.