Recruitment of pre-existing networks during the evolution of C4 photosynthesis

During C4 photosynthesis, CO2 is concentrated around the enzyme RuBisCO. The net effect is to reduce photorespiration while increasing water and nitrogen use efficiencies. Species that use C4 photosynthesis have evolved independently from their C3 ancestors on more than 60 occasions. Along with mimicry and the camera-like eye, the C4 pathway therefore represents a remarkable example of the repeated evolution of a highly complex trait. In this review, we provide evidence that the polyphyletic evolution of C4 photosynthesis is built upon pre-existing metabolic and genetic networks. For example, cells around veins of C3 species show similarities to those of the C4 bundle sheath in terms of C4 acid decarboxylase activity and also the photosynthetic electron transport chain. Enzymes of C4 photosynthesis function together in gluconeogenesis during early seedling growth of C3 Arabidopsis thaliana. Furthermore, multiple C4 genes appear to be under control of both light and chloroplast signals in the ancestral C3 state. We, therefore, hypothesize that relatively minor rewiring of pre-existing genetic and metabolic networks has facilitated the recurrent evolution of this trait. Understanding how these changes are likely to have occurred could inform attempts to install C4 traits into C3 crops.CONACy

Realizing Regional Food Security Through Community Food Business Development in East Nusa Tenggara Province, Indonesia

This study aims to formulate a regional food security model based on the relationship between characteristics of the area of production, consumption and entrepreneurship with the performance of community food business development (PUPM) in the Province of East Nusa Tenggara (NTT). The research sample consisted of 93 rice farmers, 96 rice consumers and 30 business people representing the Association of Farmers' Groups (Gapoktan) and the Indonesian Farmers Shop (TTI) owners, accounting for the total respondents to 219 people. Data analysis was using Smart-PLS. The results of the analysis show that the performance of the PUPM in NTT which is influenced by the characteristics of the production, consumption and entrepreneurship areas has only been achieved at a sufficient level. The analysis also shows that the new PUPM activities in NTT are able to fulfill aspects of access and stability, while the availability aspect is still very small. Nevertheless, this study has proven that the regional food security model in NTT can be realized through community food business development activities

Pension system reforms in Argentina : why the u-turn?

The 2008 Argentine pension reform represented a new change of paradigm in the country’s pension policy. It encompassed the elimination of the fully funded, defined contribution (DC), private tier of the so-called Integrated Retirement and Pensions System (SIJP) – a two-tiered arrangement implemented in 1994 and inspired by the World Bank’s recommendations contained in the work Averting the Old Age Crisis (World Bank 1994). And the shift back to a publicly managed, single-tiered pension system provided in a pay-as-you-go defined benefit (PAYG-DB) basis: the Argentine Integrated Retirement System (SIPA). In order to finally explain these events, in this thesis I present a detailed account of the events that took place in 2008, divided into six chapters. The first chapter introduces the topic, its background and the research question: Why did Argentina change its pension system back to a one-tiered, pay as you go DB system in 2008? The second explains the appropriateness of the research strategy and the design chosen for this study. In the third chapter, the reader is introduced to the events under analysis and the possible explanations or “suspects” to be explored upon. The fourth chapter provides the framework and settings to understand Argentina’s policy making process. Chapter five brings in with detail the sequence of decisions that resulted in the shift back to a pay-as-you-go DB public pension design in Argentina, connecting them with that group of “suspects” (11 hypotheses) that may explain why it happened. Finally, chapter six rounds up and analyses the findings and closes with the final conclusions and recommendation for further investigation. To briefly summarize some of the findings that made possible this shift back to pay-as-you-go: (a) the effect that changes in public representations of social problems have over the sustainability of their associated social arrangements. (b) The transformations in the private-public mix that have been happening in Argentine society since 2003, and the development of a different understanding of role of the State. (c) The multidimensional feature of social policy – and in particular pension policy – and the way the various dimensions are prioritized and discussed upon during the policy formulation process, leading to a certain “consensual” understanding of what the problem is and how it should be solved. (d) The impact that certain aspects of political cultures – such as the presence of machine politics or ideology – may have over policy and the process of policy change, influencing arguments and final outcomes. (e) The shaping role of institutions and electoral results in the whole policy making process. (f) The new map of international relationships, in particular with the IMF and the World Bank. (g) And how local and international contexts create certain settings that can affect the views of all actors involved.Master in International Social Welfare and Health Polic

Compact City approach versus Self-Sufficient City approach : two models of urban sustainability. A bibliographic review

The motivation of this research is to realise a bibliographic review of the literature about Compact City and Self-Sufficient City approaches to reach urban sustainability. There is much debate in the scientific community about which approach is more successful or more accessible, so this bibliographic review serves to explore these debates and analyze some of the deeper ideologies between these urban sustainability approaches. The study uses literature published between 2008 to 2020 regarding seven regions around the world, the seven regions are Africa, Asia, Australia, Europe, Latin America, Middle East, and North America. The decision to begin the search in 2008 was due to the fact that the financial crisis marked a noticeable change in urban sustainability models. As many cities around the world were essentially rebuilding after the crisis, they were also rethinking the environmental and social impact of urban development

Analytic and geometric properties of photoinduced effects in noncentrosymmetric crystals: photovoltaic current and optical rectification

An original dispersion relation between the stationary coherent nonlinear optical responses by current and polarisation is obtained. The dispersion relation provides a new complimentary tool that can be employed to study light-induced charge transport models and facilitate experimental data analysis. It is shown that the origin of the coherent current and the dc-polarisation induced in a noncentrosymmetric crystal under illumination is related to the theory of the Berry phase and can be represented in terms of the renormalised geometric potentials. This renormalisation originates from the extra phase difference acquired by a carrier in the light field on the quantum transition between the electronic bands. The gauge invariance of the corresponding expressions for the current and the polarisation is demonstrated.Comment: 7 page

Liderazgo transformacional en la Universidad Nacional del Centro del Perú, según la percepción de los docentes

Objective. To determine the level of transformational leadership predominant in the authorities of the Universidad Nacional del Centro del Perú in Huancayo, according to the perception of teachers. Methods. The study had a quantitative approach, basic type and non-experimental, cross-sectional and simple descriptive design. The population consisted of 823 teachers of the University, distributed among 25 faculties. The sample consisted of 150 teachers, selected by non-probabilistic sampling by quotas. For data collection, the abbreviated multifactorial leadership questionnaire (MLQ short form 5X) of Bass and Avolio (1997) was applied. Results. A preponderance of high level of transformational leadership was found (46.7 %), followed by moderate level (32 %), low level (12 %), very high level (6.7 %) and very low level (2.7 %). Conclusion. According to the perception of teachers, a high level of transformational leadership predominates in the authorities of the Universidad Nacional del Centro del Perú in Huancayo.Objetivo. Determinar el nivel de liderazgo transformacional predominante en las autoridades de Universidad Nacional del Centro del Perú de Huancayo, según la percepción de los docentes. Métodos. El estudio fue de enfoque cuantitativo, tipo básico y diseño no experimental, trasversal y descriptivo simple. La población estuvo constituida por los 823 docentes de la Universidad, distribuidos en 25 facultades. La muestra estuvo integrada por 150 docentes, seleccionados mediante muestreo no probabilístico por cuotas. Para la recolección de datos se aplicó el cuestionario abreviado multifactorial del liderazgo (MLQ forma 5X corta) de Bass y Avolio (1997). Resultados. Se halló preponderancia del nivel alto de liderazgo transformacional (46,7 %), seguido por el nivel moderado (32 %), nivel bajo (12 %), nivel muy alto (6,7 %) y nivel muy bajo (2,7 %). Conclusión. Según la percepción de los docentes, en las autoridades de la Universidad Nacional del Centro del Perú de Huancayo predomina un nivel alto de liderazgo transformacional

Chaotic motion of space charge wavefronts in semiconductors under time-independent voltage bias

A standard drift-diffusion model of space charge wave propagation in semiconductors has been studied numerically and analytically under dc voltage bias. For sufficiently long samples, appropriate contact resistivity and applied voltage - such that the sample is biased in a regime of negative differential resistance - we find chaos in the propagation of nonlinear fronts (charge monopoles of alternating sign) of electric field. The chaos is always low-dimensional, but has a complex spatial structure; this behavior can be interpreted using a finite dimensional asymptotic model in which the front (charge monopole) positions and the electrical current are the only dynamical variables.Comment: 12 pages, 8 figure