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Search Results: 1 - 10 of 34692 matches for " bio-energetic model "
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Network complexity and species traits mediate the effects of biological invasions on dynamic food webs
Miguel Lurgi,Núria Galiana,Bernat C. López,Lucas N. Joppa,José M. Montoya
Frontiers in Ecology and Evolution , 2014, DOI: 10.3389/fevo.2014.00036
Abstract: Biological invasions are a major threat to natural communities worldwide. While several species traits have been identified as important determinants of invasion success, a systematic exploration of the effects of invasions on native communities, and the role of species and community features on community robustness in the face of invasion is lacking. We present a theoretical approximation considering food web structure and species population dynamics to study the effects of invasions on complex food webs. We find that less complex (i.e., less connected) food webs are more resistant to invasions. Simulated invasions promote profound changes in several food web properties and stability measures, such as decreases in modularity and the number of food chains from basal to top species; and a decoupling of community- and population-level temporal variability. Additionally, species traits such as body size and diet breadth are strong determinants of invasion success across several trophic levels, with larger and more generalist species being more successful invaders in general. Our work complements species-centered invasion studies by adding a more holistic and systematic perspective to the study of invasions on species interaction networks.
ECONOMIC EVALUATION OF TECHNOLOGIES OF CULTIVATION OF MAIZE AFTER GRAIN AND WINTER WHEAT IN THE CONDITIONS OF THE PINNED LOWLANDS AGRO-LANDSCAPE OF THE CENTRAL ZONE OF THE KRASNODAR REGION Экономическая оценка технологий возделывания кукурузы на зерно и озимой пшеницы в условиях низменно-западинного агроландшафта центральной зоны Краснодарского края
Velikanova L. O.,Siso A. V.
Polythematic Online Scientific Journal of Kuban State Agrarian University , 2013,
Abstract: The article deals with the economic evaluation of seven studied alternative technologies for cultivation of winter wheat and corn in conditions of the pinned low-lands agro-landscapes of the Central zone of the Kras-nodar region. The high efficiency of the reclamation technology of cultivation has been revealed
A Mathematical Model to Solve Bio-Heat Transfer Problems through a Bio-Heat Transfer Equation with Quadratic Temperature-Dependent Blood Perfusion under a Constant Spatial Heating on Skin Surface  [PDF]
Emmanuel Kengne, Idir Mellal, Mariem Ben Hamouda, Ahmed Lakhssassi
Journal of Biomedical Science and Engineering (JBiSE) , 2014, DOI: 10.4236/jbise.2014.79071
Abstract: We consider the one-dimensional bio-heat transfer equation with quadratic temperature-dependent blood perfusion, which governs the temperature distribution inside biological tissues. Using an extended mapping method with symbolic computation, we obtain the exact analytical thermal traveling wave solution, which describes the non-uniform temperature distribution inside the bodies. The found exact solution is used to investigate the temperature distribution in the tissues. It is found that the surrounding medium with higher temperature does not necessarily imply that the tissue will quickly (after a short duration of heating process) reach the desired temperature. It is also found that increased perfusion causes a decline in local temperature.
Perspectivas de la situacion energética mundial. Las oportunidades para Colombia
Infante Villarreal,Arturo;
Revista de Ingeniería , 2007,
Abstract: almost one fourth of the energy consumed in the u.s. comes from imported oil and only 6% is produced from renewable sources despite the fact that the u.s. is responsible for 20% of the global pollution with barely 4% of the world population. biofuels are a promising source of renewable energy for the united states and the rest of the world, with favorable energy and environmental balances. if price conditions are adequate for the basic input producers, biofuels will have an important social impact, as well. colombia has the possibility to participate in the national and international biofuel substitution markets for gasoline and diesel with ethanol and biodiesel, respectively. oil palm, sugar cane and yuca, are the raw materials with the best potential.
Fabrication of Bio―ceramic Bone Model
LIU Fwu-Hsing, CHEN Ssu-Han
无机材料学报 , 2012, DOI: 10.3724/sp.j.1077.2012.00348
Abstract: The process parameters and raw materials of current commercial rapid prototyping (RP) machines are limited, thus the bone model is not easily to fabricate. In order to overcome these disadvantages, a self―developed rapid prototyping machine was used to produce bone model. In this work, the hydroxyapatite (HA), silica sol and suspending agent were mixed as raw materials. By adjusting the suitable process parameter, the bio―ceramic green parts could be formed, and then the specimen green parts were sintered at 1200 1300 1400 respectively. The shrinkage, surface roughness and compression strength were tested. Furthermore, the cell activities of the bone model were investigated through the osteoblast MG63 cells culture. The results showed that the green part sintered at 1200 xhibits optimum properties with greatly improved compression strength and surface roughness of Ra (12.04 μm), which is suitable for the growth of the osteoblast MG63.
Extended Generalized Riccati Equation Mapping for Thermal Traveling-Wave Distribution in Biological Tissues through a Bio-Heat Transfer Model with Linear/Quadratic Temperature-Dependent Blood Perfusion  [PDF]
Emmanuel Kengne, Fathi Ben Hamouda, Ahmed Lakhssassi
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410199
Abstract:

Analytical thermal traveling-wave distribution in biological tissues through a bio-heat transfer (BHT) model with linear/quadratic temperature-dependent blood perfusion is discussed in this paper. Using the extended generalized Riccati equation mapping method, we find analytical traveling wave solutions of the considered BHT equation. All the travelling wave solutions obtained have been used to explicitly investigate the effect of linear and quadratic coefficients of temperature dependence on temperature distribution in tissues. We found that the parameter of the nonlinear superposition formula for Riccati can be used to control the temperature of living tissues. Our results prove that the extended generalized Riccati equation mapping method is a powerful tool for investigating thermal traveling-wave distribution in biological tissues.

Decomposition Analysis of the Mechanism Behind the Spatial and Temporal Patterns of Changes in Carbon Bio-Sequestration in China
Jinyan Zhan,Haiming Yan,Bin Chen,Jiao Luo,Nana Shi
Energies , 2012, DOI: 10.3390/en5020386
Abstract: Great attention has been paid to carbon bio-sequestration due to increasing concerns over global warming. Understanding the relationship between carbon bio-sequestration and its influencing factors is of great significance for formulating appropriate management measures for global warming mitigation. Since change in carbon bio-sequestration is a complex process, it is difficult to take into account all of its influencing factors, while the panel data model may provide an effective way to measure their subtle effects. In this paper, decomposition analysis is applied to further analyze these influencing factors. The results indicate that climatic, demographic and geographical variables play important roles in explaining the spatial heterogeneity of carbon bio-sequestration in China, which is consistent with previous researches. Meanwhile, the irrigation rate is found to be the most critical factor influencing carbon bio-sequestration changes, followed by climatic and economic factors. These results may provide decision makers in China with important scientific reference information for formulating regional carbon bio-sequestration management policies, which are of great significance to alleviating and adapting to global warming.
ANáLISIS DE LA EVOLUCIóN DE LA PRODUCCIóN CIENTíFICA PRESENTADA EN EVENTOS ACADéMICOS DE PSICOLOGíA DE LA SALUD EN AMéRICA LATINA
Werner Sebastiani,Ricardo; Chaves Maia,Eulália Maria;
Acta Colombiana de Psicología , 2006,
Abstract: this research have developed a comparative study between the evolution of scientific production of health psychology in latin america and transformations that this subcontinent tried throughout last the 20 years, either in the context of political and economic changes, and socio-sanitary demands, either in the transistions of paradigms in health, demography and epidemiology. from studies carried out in cuba, chile, colombia, méxico and brazil, and research presentations of latin american health psychologist in 14 academic events developed between 1985 and 2003, it is evidenced the growth of the specialty, with a strong sinergy between the changing needs of latin american people and the ready response of psychologists to these problems, as well as an interesting correlation between practice and theory, where the transdisciplinary identity of the specialty and the challenge to strengthening the relationship between thinking and action show important proposals, actions and methods of intervention. whereas they contemplate people needs, they widen the action field of psychology to the four dimensions of health care - promotion and education, prevention, treatment, and palliative cares or rehabilitation. psychology as a science and professional psychologists have increasingly found in this field a very important social insertion and strengthening of their proposals of health care, gaining important spaces in the design of public policy in their countries. however, it is neccesary improving with respect to research methods and intervention strategies, as well as in the proposals of postgraduate courses that make possible a more consistent formation of new generations of psychologists with commitment, who make front to the latin american reality, very different to developed countries in the northern hemisphere.
Kinetic model of pectin demethylation
Constenla,D.; Lozano,J.E.;
Latin American applied research , 2003,
Abstract: pectins are polysaccharides that act as a cellular binder in the peel of many different fruits and vegetables. an important feature of pectins is the esterification of the galacturonic acid residues with methanol. the degree of methylation is defined as the number of moles of methanol per 100 moles of galacturonic acid. the objective of the present work was to study the acid demethylation of apple pectin at different temperatures, by following changes in the degree of methylation. a solution of high methoxyl apple pectin was demethylated with concentrated hcl (ph = 0.5). the processes were carried out for 120 min at t = 80°c and 400 min at t = 65°c and t = 50°c. anhydrogalacturonic acid content, degree of methylation and intrinsic viscosity as a function of reaction time were determined. results showed pectin demethylation followed a second order kinetics and demethylation rate increased exponentially with temperature. results also showed pectin "purity", as anhydrogalacturonic acid content, increased with demethylation. however, intrinsic viscosity reduced with reaction time. this behavior was associated with the hydrolysis of non-polyuronic material during the acid treatment, lowering in that way the average molecular weight.
Análise do impacto nos custos de transporte de um modelo de sele??o de fornecedores baseado em variáveis socioambientais e de competitividade
Carmo, Breno Barros Telles do;Barros Neto, Julio Francisco;Dutra, Nadja Glheuca da Silva;
Produ??o , 2011, DOI: 10.1590/S0103-65132011005000013
Abstract: nowadays, there is a world demand for renewable energies. these kinds of energy must be sustainable to be considered renewable. the consumption of diesel has increased and so has the emission of greenhouse gases. bio-diesel is an alternative to reduce this kind of emission. but, when the matter is bio-diesel, there are some challenges to be overcome. this first one is that this chain must be competitive. there are some criteria to evaluate the competitiveness of chains. also, it is known that brazil has a big potential to export this kind of fuel. however, some countries are developing norms to evaluate whether this fuel is sustainable and whether it has positive impacts in society. the present work creates a model to evaluate bio-diesel chain suppliers using competitiveness and certification criteria identified in this chain. smarter methodology was used in order to do so. this model was put together along with a transport optimization model. it could be observed that the "selo social" has an important impact in transportation costs. when we analyzed competitiveness and certification evaluation models, we could observe that these suppliers evaluation model changes this relationship.
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