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Garcia-Amado L.R.,Autonomous University of Madrid | Perez M.R.,Autonomous University of Madrid | Escutia F.R.,University of Arts and Science of Chiapas | Garcia S.B.,Colegio de Mexico | Mejia E.C.,University of Arts and Science of Chiapas
Ecological Economics | Year: 2011

Payments for Environmental Services (PES) have been claimed as a more efficient way of accomplishing conservation and development goals than other indirect strategies, reaching their optimum when the buyer pays the opportunity costs of the foregone benefits. Different inefficient situations have been described, like lack of additionality, where payments are given for practices that would have been adopted anyway. Trade-offs between efficiency and equity of PES have usually emerged as well. In this paper we assess the equity, additionality and stakeholders' perceptions of a PES scheme in a Mexican community inside a Biosphere Reserve. We applied structured interviews to all adults, a total of 66 people from 31 households. Our results show a dual response in equity and additionality, depending on land tenure. PES have an egalitarian effect within landowners and landless groups, but it broadens the gap between them. Additionality is low for landowners and high for the landless people in the community, even though the former are the ones with full decision over the land. Although the scheme does not seem efficient under the classical PES paradigm, it is perceived as a reward, reinforcing conservation attitudes even though most of the interviewees claim it to be insufficient. © 2011 Elsevier B.V.


Ibanez G.,University of Arts and Science of Chiapas | Lopez A.,Chiapas Polytechnic University | Cuevas S.,National Autonomous University of Mexico
International Communications in Heat and Mass Transfer | Year: 2012

The influence of the geometrical and physical parameters on entropy generation for a viscous flow between infinite parallel walls of finite thickness is studied by solving the momentum and energy conservation equations. The conjugate heat transfer problem in the fluid and solid walls is solved analytically using thermal boundary conditions of the third kind at the outer surfaces of the walls and continuity of temperature and heat flux across the fluid-wall interfaces. Analytic solutions for the velocity and temperature fields in the fluid and walls are used to calculate the local and global entropy generation rate. Conditions under which this quantity is minimized are determined for certain suitable combination of geometrical and physical parameters of the system. Special attention has been given to the effect of the wall thickness on the entropy generation rate. It is found that the global entropy generation reaches a minimum for specific values of the wall thickness ratio, when the other parameters are fixed. © 2012 Elsevier Ltd.


Ibanez G.,University of Arts and Science of Chiapas | Cuevas S.,National Autonomous University of Mexico
Energy | Year: 2010

The dissipative processes that arise in a microchannel flow subjected to electromagnetic interactions, as occurs in a MHD (magnetohydrodynamic) micropump, are analyzed. The entropy generation rate is used as a tool for the assessment of the intrinsic irreversibilities present in the microchannel owing to viscous friction, heat flow and electric conduction. The flow in a parallel plate microchannel produced by a Lorentz force created by a transverse magnetic field and an injected electric current is considered assuming a thermally fully developed flow and conducting walls of finite thickness. The conjugate heat transfer problem in the fluid and solid walls is solved analytically using thermal boundary conditions of the third kind at the outer surfaces of the walls and continuity of temperature and heat flux across the fluid-wall interfaces. Velocity, temperature and current density fields in the fluid and walls are used to calculate the global entropy generation rate. Conditions under which this quantity is minimized are determined for specific values of the geometrical and physical parameters of the system. The Nusselt number is also calculated and explored for different conditions. Results can be used to determine optimized conditions that lead to a minimum dissipation consistent with the physical constraints demanded by the microdevice. © 2010 Elsevier Ltd.


Sanchez-Cortes M.S.,University of Arts and Science of Chiapas | Chavero E.L.,National Autonomous University of Mexico
Climatic Change | Year: 2011

This study analyses the perceptions of Zoque indigenous men and women of changes in climate variability, indicated by rainfall and temperature records from the region. Peasant farmers perceive decreases in rainfall and increases in temperature as these factors are related to modifications in the corn planting season and the introduction of crops which were usually only found in hot regions. The climate changes in the zone are attributed to vegetation loss and the eruption of the Chichón volcano in 1982. The Zoque perception is structured according to cultural and individual experience, tied to agriculture and the annual weather calendar. The volcanic eruption offers a significant chronological reference point in order to explain different environmental transformations, such as climate, within Zoque territory. Perception is the mental picture of local climate variability changes and the responses in seasonal agriculture modifications, utilizing individual and cultural experiences which are vulnerable to economic and environmental change. © 2010 Springer Science+Business Media B.V.


Ibanez G.,University of Arts and Science of Chiapas
International Journal of Heat and Mass Transfer | Year: 2015

Combined effects of hydrodynamic slip, magnetic field, suction/injection and convective boundary conditions on the global entropy generation in steady flow of an incompressible electrically conducting fluid through a channel with permeable plates are studied. Analytical solutions of the governing equations are obtained in closed form. Particularly, using thermal boundary conditions of the third kind, the temperature field is derived analytically. Also, the influences of the governing parameters on global entropy generation are discussed in detail and depicted graphically. The analysis of our results indicates that entropy generation minimization can be achieved by appropriate combination of the geometrical and physical parameters of the system. It is possible to determine optimum values of Hartmann number, Biot number and Prandtl numbers which lead to a minimum global entropy generation rate. The effects of slip flow on the optimum values of some other parameters are also explored. © 2014 Elsevier Ltd. All rights reserved.


Martinez-Perez M.,University of Arts and Science of Chiapas
Advances in child development and behavior | Year: 2015

This chapter examines how 2-year-old children attempt to actively participate in adult work in a Mayan community in Chiapas, Mexico, and how adults contribute and accommodate to the contributions. As children enter into activities and adults orient and reorient the activity to direct the children, teaching from expert to novice is generated by children's agency in co-participatory interactions. The chapter enriches the LOPI model by focusing on the structure of participation and communication, social and community organization, and the evaluation that occurs in the activity itself. © 2015 Elsevier Inc. All rights reserved.


De La Cruz Chacon I.,University of Arts and Science of Chiapas | Gonzalez-Esquinca A.R.,University of Arts and Science of Chiapas
Natural Product Research | Year: 2012

Plants of the Annonaceae family produce a series of alkaloids, including liriodenine oxoaporphine. Its distribution in these primitive angiosperms suggests that it plays an important role, but very little is known about which plant organs it accumulates in, or in which developmental stages it is synthesised. Accordingly, liriodenine production was studied during the early stages of germination and seedling development in Annona diversifolia Saff. Liriodenine samples were obtained from the roots and were characterised on the basis of spectroscopic data. Quantification was done by HPLC in the organs and tissues of newly collected seeds, seeds following 1-, 2-, 5- and 10-day imbibitions, upon emergence of the radicle and at the seedling stage. According to our results, liriodenine could not have originated from the parent plant, nor during embryogenesis because it appears for the first time in the endosperm approximately 5 days after the start of imbibition. Therefore, its synthesis does not depend directly on photosynthesis. During the seedling stage it is found in the root and the stem but it is absent from the cotyledonary leaves and the first true leaves. Liriodenine biosynthesis begins during the early stages of development in the endosperm and seed radicles. © 2012 Copyright Taylor and Francis Group, LLC.


Martinez-Perez M.,University of Arts and Science of Chiapas
Advances in Child Development and Behavior | Year: 2016

This chapter examines how 2-year-old children attempt to actively participate in adult work in a Mayan community in Chiapas, Mexico, and how adults contribute and accommodate to the contributions. As children enter into activities and adults orient and reorient the activity to direct the children, teaching from expert to novice is generated by children's agency in co-participatory interactions. The chapter enriches the LOPI model by focusing on the structure of participation and communication, social and community organization, and the evaluation that occurs in the activity itself. © 2015 Elsevier Inc.


Ibanez G.,University of Arts and Science of Chiapas | Lopez A.,University of Arts and Science of Chiapas | Pantoja J.,University of Arts and Science of Chiapas | Moreira J.,University of Arts and Science of Chiapas | Reyes J.A.,University of Arts and Science of Chiapas
Energy | Year: 2013

The effects of slip flow on heat transfer and entropy generation by considering the conjugate heat transfer problem in microchannels are studied, analytically. The heat transfer equations in the fluid and the finite thickness walls of the microchannel are solved analytically using thermal boundary conditions of the third kind at the outer surfaces of the walls and continuity of temperature and heat flux across the fluid-wall interfaces. After the analytic solutions for the velocity and temperature fields in the fluid and walls of microchannel are obtained, the entropy generation rate is discussed in detail and investigated considering slip flow and convective effects, simultaneously. The results show that the global entropy generation rate is minimized for certain suitable combination of the geometrical and physical parameters of the system. It is possible to find an optimum slip velocity which leads to a minimum global entropy generation rate. The Nusselt number is also calculated and explored for different conditions. An optimum value of the slip length that maximizes the heat transfer is derived. © 2012 Elsevier Ltd.


Ruiz Meza L.E.,University of Arts and Science of Chiapas
Climate and Development | Year: 2015

This paper identifies conditions of social vulnerability and climate-related disaster risk in the Huehuetán River basin, Chiapas, Mexico and analyses the capacity of small coffee producers to adapt to hydrometeorological hazards. Small-scale farmers in the basin use various strategies to adapt to the impacts of such hazards and to confront the deterioration of their livelihoods, including diversifying the varieties of coffee they cultivate, diversifying their sources of income, and emigration. Analysis of these strategies suggests that high levels of poverty, coffee monoculture, food insecurity, and instability in sources of employment and income combine to limit the flexibility and stability of population's adaptive capacity. The strategies employed by local people have allowed for short-term subsistence but offer little chance of long-term sustainability. Conditions do not appear to reduce social vulnerability and, in fact, undermine local resilience that would reduce damage and risks from extreme climate events. The impacts of climate change are placing the region's small farmers in a very vulnerable situation from which it may be difficult to escape, without the implementation of social reform predicated on greater justice and social equality, which will require political will. This case illustrates the challenges that must be addressed in order to overcome the social inequalities that prevent small-farmer communities from reducing their vulnerability in the face of climate-(or non-climate-) related risks. © 2014, © 2014 Taylor & Francis.

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