An agent-based approach to model land-use change at a regional scale

Land-use/cover change (LUCC) is a complex process that includes actors and factors at different social and spatial levels. A common approach to analyse and simulate LUCC as the result of individual decisions is agent-based modelling (ABM). However, ABM is often applied to simulate processes at local scales, while its application in regional studies is limited. This paper describes first a conceptual framework for ABM to analyse and explore regional LUCC processes. Second, the conceptual framework is represented by combining different concepts including agent typologies, farm trajectories and probabilistic decision-making processes. Finally, the framework is illustrated through a case study in the Netherlands, where processes of farm cessation, farm expansion and farm diversification are shaping the structure of the landscape. The framework is a generic, straightforward approach to analyse and explore regional LUCC with an explicit link to empirical approaches for parameterization of AB

Optically induced birefringence in a azopolymer based on the phenomenon of photo-isomerization

The following article is a study of optically induced birefringence in an azopolymer Hema-HDR13. Generating anisotropy in the material through the photo-isomerization process for azo-compounds, chromophores are reoriented in the material through an external electric field, from an Nd: YAG laser, emitting with a wavelength of 532.8nm Based on an absorption spectrum on an azopolímero samples was determined that the wavelength at which the phenomenon is given. Measurements were obtained for samples birefringence how efficient are able to observe the samples so that they can be used as raw material for optical storage devices. Varying the excitation laser power (Nd: YAG) were observed variations in signal strength, making observe a maximum saturation power chromophores which are reoriented in the sample. Also analyzed the theoretical models of photo-molecular orientation, and succeeded in identifying which of them corresponds to the results and establishing the characteristic times appearing in each for Hema-DR13

Construcción del conocimiento didáctico del contenido biológico en formación inicial de profesores

Presentamos la sistematización de los datos obtenidos a partir de los documentos que presentaron dos grupos de futuros profesores de Biología, a lo largo de un semestre, al diseñar Unidades Didácticas para la enseñanza de dos temáticas relacionadas con el auto-mantenimiento de los organismos. Analizamos los referentes de los docentes en formación acerca del Conocimiento Didáctico del Contenido Biológico (contemplamos 9 categorías de investigación) y los cambios de los mismos durante el proceso formativo en el que los estudiantes-profesores realizaron la propuesta

Integrated Crop Livestock Systems--A Key to Sustainable Intensification in Africa

Mixed crop-livestock systems provide livelihoods for a billion people and produce half the world’s cereal and around a third of its beef and milk. Market orientation and strong and growing demand for food provide powerful incentives for sustainable intensification of both crop and livestock enterprises in smallholders’ mixed systems in Africa. Better exploitation of the mutually reinforcing nature of crop and livestock systems can contribute to a positive, inclusive growth trajectory that is both ecologically and economically sustainable. In mixed systems, livestock intensification is often neglected relative to crops, yet livestock can make a positive contribution to raising productivity of the entire farming system. Similarly, intensification of crop production can pay dividends for livestock and enhance natural resources management, especially through increased biomass availability. Intensification and improved efficiency of livestock production means less greenhouse gases per unit of milk and more milk per unit of water. This paper argues that the opportunities and challenges justify greater investment in research for development to identify exactly where and how win-win outcomes can be achieved and what incentives, policies, technologies and other features of the enabling environment are needed to enable sustainable, integrated and productive mixed crop livstock systems

Hydrodynamics and water quality assessment of a coastal lagoon using environmental fluid dynamics code explorer modeling system

Ciénaga de Mallorquín is a coastal lagoon designated as a RAMSAR site due to its ecological regional and international importance. In this work, the environmental fluid dynamics code explorer modeling system was implemented to determine the spatiotemporal distribution of temperature, dissolved oxygen, chemical oxygen demand and nutrient levels, and assess the trophic status of Ciénaga de Mallorquín. The model was set up with field measurement data taken during transition period and wet season, and secondary information obtained from local authorities and environmental agencies. The results of model simulations were calibrated and verified by the root mean square error method, achieving a consistent fit for all considered variables. Average velocities were between 0.006 m/s and 0.013 m/s during the analyzed periods. The temperature was higher in the wet season than in the transition period (29°C and 31.5°C, respectively). The dissolved oxygen was similar in both periods (6.6 and 6.7 mg/L). NO3 concentrations were higher during the transition period (3.28 mg/L), with a minimum of 1.76 mg/L and a maximum of 5.09 mg/L. The lowest NO3 concentrations were found in the area influenced by the connection with the Caribbean Sea. PO4 concentrations in the wet season were lower than in the transition period (0.20 mg/L). Finally, Ciénaga de Mallorquín exhibits high productivity levels with Trophic State Index > 50 and temporal variations of mesotrophic to eutrophic. The use of Trophic State Index is useful for the management of water body eutrophication and productivity, making it particularly important in aquatic ecosystems

Crop residue allocation to livestock feed, soil improvement and other uses along a productivity gradient in Eastern Africa

Crop residues are a key livelihood resource in smallholder mixed crop-livestock systems in Sub-Saharan Africa. With expansion of arable land and resultant decline in grazing resources, crop residues are becoming an increasingly important component of livestock feeds. This demand for livestock feeds has implications for the long-term sustainability of such systems since failure to return biomass to soils has implications for soil quality and the capacity of soils to support long-term productivity. Biomass allocation patterns are likely to vary with overall level of productivity and hence availability. In this study we used a household survey to quantify crop residue allocation patterns across a gradient of productivity in Eastern Africa focusing on two sites in Ethiopia and one in Kenya. We assessed the underlying determinants of crop residue allocation patterns with a view to understanding how productivity increases through intensification will influence biomass allocation in Eastern Africa and how livelihood and natural resource management objectives could be optimized. Results showed that farmers strongly favour allocation of residues to livestock feeding but that allocation to soil increases along the productivity gradient. This reduced feeding to livestock and increased allocation to soil fertility is associated with smaller farm sizes leading to reduced animal traction needs for tillage, increased overall livestock productivity, increased use of inputs and a reduced reliance on farm-based activities in overall livelihood strategies. The implications of these trends are that productivity increases in smallholder systems are likely to reduce pressure on biomass in the long term and that measures that enhance the prospects for farmers to intensify their production systems are likely to increase soil health and sustainability objectives in general. A key conclusion of the work is that intensification of livestock production could reduce crop residue allocation to soils with long term implications for soil productivity

Advances in the systemic treatment of therapeutic approaches in biliary tract cancer

Biliary tract cancer; Molecular testing; Next-generation sequencingCáncer del tracto biliar; Pruebas moleculares; Secuenciación de nueva generaciónCàncer del tracte biliar; Proves moleculars; Seqüenciació de nova generacióIntroduction Biliary tract cancers (BTCs) are a rare and heterogenous group with an increasing incidence and high mortality rate. The estimated new cases and deaths of BTC worldwide are increasing, but the incidence and mortality rates in South East Asia are the highest worldwide, representing a real public health problem in these regions. BTC has a poor prognosis with a median overall survival <12 months. Thus, an urgent unmet clinical need for BTC patients exists and must be addressed. Results The backbone treatment of these malignancies is chemotherapy in first- and second-line setting, but in the last decade a rich molecular landscape has been discovered, expanding conceivable treatment options. Some druggable molecular aberrations can be treated with new targeted therapies and have already demonstrated efficacy in patients with BTC, improving clinical outcomes, such as the FGFR2 or IDH1 inhibitors. Many other molecular alterations are being discovered and the treatment of BTC will change in the near future from our current clinical practice. Conclusions In this review we discuss the epidemiology, molecular characteristics, present treatment approaches, review the recent therapeutic advances, and explore future directions for patients with BTC. Due to the rich molecular landscape of BTC, molecular profiling should be carried out early. Ongoing research will bring new targeted treatments and immunotherapy in the near future

Construcción del conocimiento didáctico del contenido biológico en formación inicial de profesores

Presentamos la sistematización de los datos obtenidos a partir de los documentos que presentaron dos grupos de futuros profesores de Biología, a lo largo de un semestre, al diseñar Unidades Didácticas para la enseñanza de dos temáticas relacionadas con el auto-mantenimiento de los organismos. Analizamos los referentes de los docentes en formación acerca del Conocimiento Didáctico del Contenido Biológico (contemplamos 9 categorías de investigación) y los cambios de los mismos durante el proceso formativo en el que los estudiantes-profesores realizaron la propuesta

Biomass in crop-livestock systems in the context of the livestock revolution

Mixed crop-livestock systems are the dominant source of livelihood supporting more than 80% of people living in the developing world and producing 50% of world cereals, around 34% of the global beef production and about 30% of global milk production. However, mixed systems are coming under increasing pressure with their human population predicted to increase from 1,099 million in 2000 to 1,670 million people in 2030 and their cattle population to increase from 230 million to 317 million from 2000 to 2030. Coupled with this increase in human and livestock populations, cereal yields have been stagnating in sub-Saharan Africa (SSA) for the last 40 years (in contrast to growth rates of 1.5-2% per year for the rest of the developing world), with most increase in overall cereal production arising from expansion of arable land. Such trends cannot be maintained as land suitable for cropping is scarce, and additional cropland might also be more marginal and subject to greater climatic risks. There is increasing pressure on biomass in mixed systems and there are strong needs to find ways out of this ‘‘biomass trap’’ through increasing overall biomass yield and fodder quality and through increasing the efficiency of livestock production. Biomass from crop residues (CR) is used as a feed resource and as mulch to improve crop yields. Biomass is becoming scarcer and competition for CR is becoming more severe. This is reflected in changes of CR use from grazing to harvesting and storage, longer distances across which CR are transported and transacted and decreasing CR to grain ratios. The predicted increase in demand for livestock products, the so-called livestock revolution, will further fuel feed demand and increase the usage of CR for livestock feeding. Use of CR for mulch and conservation agriculture demands about 2 to 3 tons of CR per hectare which is often equal to their total yield under rain-fed conditions in the semi-arid tropics. Multidimensional crop improvement can mitigate competition for biomass by increasing CR quantity and by improving fodder quality. Increased CR yield will facilitate partitioning of CR between livestock and soil improvement and improved CR fodder quality will support intensification of livestock production where more animal sourced foods (ASF) can be produced with less feed. It is important to realize that feed biomass requirement is very context specific and decreases with increasing per unit animal productivit