A Modelling Framework for Addressing the Synergies between Global Conventions through Land Use Changes: Carbon Sequestration, Biodiversity Conservation, Prevention of Land Degradation and Food Security in Agricultural and Forested Lands in Developing Countries

This paper proposed a methodological framework for the assessment of carbon stocks and the development and identification of land use, land use change and land management scenarios, whereby enhancing carbon sequestration synergistically increases biodiversity, the prevention of land degradation and food security through the increases in crop yields. The framework integrates satellite image interpretation, computer modelling tools (i.e. software customization of off-the-shelf soil organic matter turnover simulation models) and Geographical Information Systems (GIS). The framework addresses directly and indirectly the cross-cutting ecological concerns foci of major global conventions: climate change, biodiversity, the combat of desertification and food security. Their synergies are targeted by providing procedures for assessing and identifying simultaneously carbon sinks, potential increases in plant diversity, measures to prevent land degradation and enhancements in food security through crop yields, implicit in each land use change and land management scenario. The scenarios aim at providing “win-win” options to decision makers through the framework’s decision support tools. Issues concerning complex model parameterization and spatial representation were tackled through tight coupling soil carbon models to GIS via software customization. Results of applying the framework in the field in two developing countries indicate that reasonably accurate estimates of carbon sequestration can be obtained through modeling; and that alternative best soil organic matter management practices that arrest shifting “slash-and-burn” cultivation and prevent burning and emissions, can be identified. Such options also result in increased crop yields and food security for an average family size in the area, while enhancing biodiversity and preventing land degradation. These options demonstrate that the judicious management of organic matter is central to greenhouse gas mitigation and the attainment of synergistic ecological benefits, which is the concern of global conventions. The framework is to be further developed through successive approximations and refinement in future, extending its applicability to other landscapes.Climate Change, Greenhouse Gas Mitigation, Carbon Sequestration, Soil Organic Matter, Modeling, Land-Use Change, Land Management, Ecological Synergies, Agriculture

Senior Capstone Project final research report : Health and Environmental Action Network

The HEAN Program is meant to identify and raise awareness of environmental health issues in Latino communities. The project involves mobile air monitoring by local youth, as well as incorporating environmental health awareness into our outreach and education, with an educational goal towards local youth. The HEAN project plans to promote health awareness not only at a local level, but at a national level as well

The noisy Hegselmann-Krause model for opinion dynamics

In the model for continuous opinion dynamics introduced by Hegselmann and Krause, each individual moves to the average opinion of all individuals within an area of confidence. In this work we study the effects of noise in this system. With certain probability, individuals are given the opportunity to change spontaneously their opinion to another one selected randomly inside the opinion space with different rules. If the random jump does not occur, individuals interact through the Hegselmann-Krause's rule. We analyze two cases, one where individuals can carry out opinion random jumps inside the whole opinion space, and other where they are allowed to perform jumps just inside a small interval centered around the current opinion. We found that these opinion random jumps change the model behavior inducing interesting phenomena. Using pattern formation techniques, we obtain approximate analytical results for critical conditions of opinion cluster formation. Finally, we compare the results of this work with the noisy version of the Deffuant et al. model for continuous-opinion dynamics

PERFLUOROCYCLOBUTYL ARYL ETHER POLYMERS FOR PROTON EXCHANGE MEMBRANES

Over the last decades Nafion¨ has emerged as the polymer of choice for the fabrication of Proton Exchange Membranes (PEM)s, due to its excellent proton conductivity and long-term stability. However, high temperatures and low relative humidity decrease fuel cell efficiency, due to the highly hydrated conditions required for proton conductivity. To overcome these issues, different types of sulfonated polymers have been proposed as promising substitutes for Nafion ¨, these include; Poly(arylene ether sulfones) (PAES) and Perfluorocyclobutyl (PFCB) aryl ether polymers among others. Chapter 2 of this thesis describes the synthesis of a new class of sulfonated PAESs containing the perfluorocyclobutyl (PFCB) unit. These polymers have been prepared by the polycondensation of a unique bis-phenol (Bisphenol -T) with dichlorodiphenylsulfone (DCDPS) and sulfonated dichlorodiphenylsulfone (SDCDPS) under nucleophilic substitution conditions. Three different molar ratios of Bisphenol -T: DCDPS: SDCDPS were used: 1:1:0, 1:0:1 and 1:0.68:0.32, (P1, P2 and P3, respectively). The degree of incorporation of the sulfonated repeat unit into the copolymers was determined by 1H NMR. The resulting polymers show solubility in polar organic solvents such as DMAc and DMSO. The incorporation of SDCDPS into the backbone of the polymer decreased the mechanical strength of the membranes. Solution casting of the unsulfonated polymer P1 yielded tough, flexible films with a glass transition temperature of 138 oC. and catastrophic weight loss in N2 at 350-450 oC. Sulfonation of polymers P2 and P3 resulted in lower molecular weight brittle films and lower stability and mechanical properties. Chapter 3 describes the incorporation of zirconia into PFCB aryl ether polymers. The complex surface of zirconia aerogel was modified by complexation with p-trifluorovinyloxy phenyl phosphoric acid. PFCB polymers with different Ionic Exchange Capacity values were obtained by sulfonation with ClSO3H (P4, P5, P6). Sulfonated PFCB polymers showed a reproducible increase in the Ionic Exchange Capacity (IEC) after the addition of 10 wt % modified zirconia, whereas unmodified zirconia resulted in lower IEC membranes. Polymers P4 and P5 improved their thermo-oxidative stability. The use of modified zirconia proved to be a simple yet valuable tool towards the fabrication of more efficient PEMs

Potassium Iodide-Functionalized Polyaniline Nanothin Film Chemiresistor for Ultrasensitive Ozone Gas Sensing.

Polyaniline (PANI) nanostructures have been widely studied for their sensitivity to atmospheric pollutants at ambient conditions. We recently showed an effective way to electropolymerize a PANI nanothin film on prefabricated microelectrodes, and demonstrated its remarkable sensing performance to be comparable to that of a one-dimensional nanostructure, such as PANI nanowires. In this work, we report further progress in the application of the PANI nanothin film chemiresistive sensor for the detection of ozone (O₃) by modifying the film with potassium iodide (KI). The KI-PANI sensor exhibited an excellent sensitivity to O₃ (8⁻180 ppb O₃ concentration rage) with a limit of detection of 230 ppt O₃, and exquisite selectivity against active chemicals such as nitrogen dioxide (NO₂) and sulfur dioxide (SO₂). The sensing mechanism of the sensor relied on iodometric chemistry of KI and O₃, producing triiodide ( I 3 - ) that partially doped and increased electrical conductivity of the PANI film. The sensitivity and selectivity of the KI-functionalized PANI film demonstrates the potential use for KI-PANI-based O₃ sensing devices in environmental monitoring and occupational safety

High Total Proton Conductivity in Large-Grained Yttrium-Doped Barium Zirconate

Barium zirconate has attracted particular attention among candidate proton conducting electrolyte materials for fuel cells and other electrochemical applications because of its chemical stability, mechanical robustness, and high bulk proton conductivity. Development of electrochemical devices based on this material, however, has been hampered by the high resistance of grain boundaries, and, due to limited grain growth during sintering, the high number density of such boundaries. Here, we demonstrate a fabrication protocol based on the sol−gel synthesis of nanocrystalline precursor materials and reactive sintering that results in large-grained, polycrystalline BaZr_(0.8)Y_(0.2O3−δ) of total high conductivity, 1 × 10^(−2) Scm^(−1) at 450 °C. The detrimental role of grain boundaries in these materials is confirmed via a comparison of the conductivities of polycrystalline samples with different grain sizes. Specifically, two samples with grain sizes differing by a factor of 2.3 display essentially identical grain interior conductivities, whereas the total grain boundary conductivities differ by a factor of 2.5−3.2, depending on the temperature (with the larger-grained material displaying higher conductivity)

Comunicación y emociones como categorías sociológicas

Recognizing the autopoietic closure of social and psychic systems, we analyze the plausibility of consider emotions as explanatory basis of social order and as ‘new’ source of knowledge of society. With this objective, we problematize the research program on emotions conceptualized as a self-description which rest on transcendental postulations –ontology, return to the subject, intersubjectivity– placing the emotions in a field of encounter between subject and society, and as a constitutive dimension of society. Although it is true that emotions are thematizable presuppositions in the communication, these cannot be the basis of society or a knowledge theory, even if they serve to take a stance on the side of emotion, with the risk of turning the reflection into a moral prescription.A partir del reconocimiento del carácter autopoiéticamente clausurado del sistema social y de los sistemas psíquicos, analizamos la plausibilidad de ponderar a las emociones en tanto elemento explicativo del orden social y en tanto ‘nueva’ fuente de conocimiento sobre la sociedad. Con este objetivo, se problematiza el programa de investigación sobre las emociones concebidas como una auto-descripción que se ampara en supuestos trascendentales –ontología, retorno al sujeto, intersubjetividad– y que instala a las emociones tanto en el ámbito de encuentro entre el sujeto y la sociedad cuanto en una dimensión constitutiva de lo social. Si bien las emociones constituyen un presupuesto susceptible de ser tematizado en la comunicación, no pueden fungir como fundamento de la sociedad ni como base de una teoría del conocimiento, aun cuando puedan servir para posicionarse del lado la emoción, con el peligro de seguir moralizando la reflexión

Synchronization and entrainment of coupled circadian oscillators

Circadian rhythms in mammals are controlled by the neurons located in the suprachiasmatic nucleus of the hypothalamus. In physiological conditions, the system of neurons is very efficiently entrained by the 24-hour light-dark cycle. Most of the studies carried out so far emphasize the crucial role of the periodicity imposed by the light dark cycle in neuronal synchronization. Nevertheless, heterogeneity as a natural and permanent ingredient of these cellular interactions is seemingly to play a major role in these biochemical processes. In this paper we use a model that considers the neurons of the suprachiasmatic nucleus as chemically-coupled modified Goodwin oscillators, and introduce non-negligible heterogeneity in the periods of all neurons in the form of quenched noise. The system response to the light-dark cycle periodicity is studied as a function of the interneuronal coupling strength, external forcing amplitude and neuronal heterogeneity. Our results indicate that the right amount of heterogeneity helps the extended system to respond globally in a more coherent way to the external forcing. Our proposed mechanism for neuronal synchronization under external periodic forcing is based on heterogeneity-induced oscillators death, damped oscillators being more entrainable by the external forcing than the self-oscillating neurons with different periods.Comment: 17 pages, 7 figure