21 resultados para Complex adaptive systems
em Scielo Saúde Pública - SP
Resumo:
The author reviews past work with Ibict and the global progress made by the Open Access Movement. He postulates a theory of open access being an example of a complex adaptive system created by Internet-based scholarly publishing. Open access could be the cause of a cascade of increasing complexity and opportunities that will reshape this system. He has chosen the pervasive and global "Connectedness" created by the internet and the content spaces it provides for open access collections as a "simple disruptive agent". He discusses how connectedness influences infinite variety, creativity, work, change, knowledge, and the information economy. Case studies from the University of New Mexico Libraries are used where appropriate.
Resumo:
Human organism is interpenetrated by the world of microorganisms, from the conception until the death. This interpenetration involves different levels of interactions between the partners including trophic exchanges, bi-directional cell signaling and gene activation, besides genetic and epigenetic phenomena, and tends towards mutual adaptation and coevolution. Since these processes are critical for the survival of individuals and species, they rely on the existence of a complex organization of adaptive systems aiming at two apparently conflicting purposes: the maintenance of the internal coherence of each partner, and a mutually advantageous coexistence and progressive adaptation between them. Humans possess three adaptive systems: the nervous, the endocrine and the immune system, each internally organized into subsystems functionally connected by intraconnections, to maintain the internal coherence of the system. The three adaptive systems aim at the maintenance of the internal coherence of the organism and are functionally linked by interconnections, in such way that what happens to one is immediately sensed by the others. The different communities of infectious agents that live within the organism are also organized into functional networks. The members of each community are linked by intraconnections, represented by the mutual trophic, metabolic and other influences, while the different infectious communities affect each other through interconnections. Furthermore, by means of its adaptive systems, the organism influences and is influenced by the microbial communities through the existence of transconnections. It is proposed that these highly complex and dynamic networks, involving gene exchange and epigenetic phenomena, represent major coevolutionary forces for humans and microorganisms.
Resumo:
The paper considers some issue in the governance of the European Protected Designation of Origin (PDO). The PDO systems are the outcomes of both farmers and consumers expectations and connect the valorisation of the agricultural and rural resources of given territories to the quality of typical products. A critical point in the governance of the PDO systems is represented by the connection between the quality strategies and the uncertainty. The paper argues that the PDO systems can be thought of as strictly coordinated subsystems in which the ex post governance play a critical role in coping with quality uncertainty. The study suggests that the society's inducements given raise to complex organizational systems in which the allocation of decision rights to PDO collective organizations play a major role. The empirical analysis is carried out by examining ten Italian PDO systems in order to identify the decision rights allocated.
Resumo:
Digital Libraries (DLs) are extremely complex information systems that support the creation, management, distribution, and preservation of complex information resources, while allowing effective and efficient interaction among the several societies that benefit from DL content and services. In this paper, we focus on our experience facing challenges of building, maintaining, and developing the Networked University Digital Library (www.nudl.org), an extension of the Networked Digital Library of Theses and Dissertations (www.ndltd.org). NUDL is a worldwide initiative that addresses making the intellectual property produced in universities more accessible, stimulating international collaboration across all disciplines. We detail technological aspects of our solutions and research activities carried out to provide powerful and enriched services for the communities served by this initiative.
Resumo:
In this work, we applied the free open source SCILAB software for the numerical integration of differential rate law equations to obtain the concentration profiles of chemical species involved in the kinetics of some complex reactions. An automated method was applied to construct the system of ordinary differential equations (ODE) from the postulated chemical models. The solutions of the ODEs were obtained numerically by standard SCILAB functions. We successfully simulated even complex chemical systems such as pH oscillators. This communication opens up the possibility of using SCILAB in simulations and modeling by our chemistry undergraduate students.
Resumo:
Biological systems are complex dynamical systems whose relationships with environment have strong implications on their regulation and survival. From the interactions between plant and environment can emerge a quite complex network of plant responses rarely observed through classical analytical approaches. The objective of this current study was to test the hypothesis that photosynthetic responses of different tree species to increasing irradiance are related to changes in network connectances of gas exchange and photochemical apparatus, and alterations in plant autonomy in relation to the environment. The heat dissipative capacity through daily changes in leaf temperature was also evaluated. It indicated that the early successional species (Citharexylum myrianthum Cham. and Rhamnidium elaeocarpum Reiss.) were more efficient as dissipative structures than the late successional one (Cariniana legalis (Mart.) Kuntze), suggesting that the parameter deltaT (T ºCair - T ºCleaf) could be a simple tool in order to help the classification of successional classes of tropical trees. Our results indicated a pattern of network responses and autonomy changes under high irradiance. Considering the maintenance of daily CO2 assimilation, the tolerant species (C. myrianthum and R. elaeocarpum) to high irradiance trended to maintain stable the level of gas exchange network connectance and to increase the autonomy in relation to the environment. On the other hand, the late successional species (C. legalis) trended to lose autonomy, decreasing the network connectance of gas exchange. All species showed lower autonomy and higher network connectance of the photochemical apparatus under high irradiance.
Resumo:
As a rule, soils of the subtropical and tropical regions, in which rainfall is not limiting, are acidic, and low in phosphorus, and, to a less extent, in other macro and micronutrients as well, such a sulfur, boron and zinc. The establishment of a permanent agricultural prac. tice therefore, demands relatively high usage of liming and phosphatic fertilization, to begin with. Several approaches, not mutually exclusive, could be used in order to increase the efficiency of utilization of soil and fertilizer phosphorus so that, goal of diminishing costs of production is reached. The use of liming materials bringing up pH to 6.0-6.5 causes the conversion of iron and aluminum phosphates to more available calcium phosphates; on the other hand, by raising calcium saturation in the exchange complex, it improves the development and operation if the root system which allows c or a higher utilization of all soil nutrients, including phosphorus, and helps of stand water deficits which may occur. The role of mycorrhizal fungi should be considered as a way of increasing soil and fertilizer P utilization, as well as the limitations thereof. Screening of and breeding for varieties with higher efficiency of uptake and utilization of soil and fertilizer phosphorus leads to a reduction in cost of inputs and to higher benefit/cost ratios. Corrective fertilization using ground rock phosphate helps to saturate the fixation power of the soil thereby reducing, as a consequence, the need for phosphorus in the maintenance fertilization. Maintenance fertilization, in which soluble phos-phatic sources are used, could be improved by several means whose performance has been proved: limimg, granula tion, placement, use of magnesium salts. Last, cost of phosphate fertilization could be further reduced, without impairing yields, through impairing yields, through changes in technology designed to obtain products better adapted to local conditions and to the availability or raw materials and energy sources.
Resumo:
Six hundred and ninety three male inmates from three penitentiaries, two (A and B) maximum-security systems and one (C) minimum-security facility, located in Campinas, State of São Paulo, Brazil were studied for the presence of human immunodeficiency virus (HIV) antibodies, using a cross-sectional design. The search for anti-HIV antibodies in 693 samples of sera collected was carried out by two serological tests: (a) the Microparticle enzyme immunoassay-HIV-1 and HIV-2 (MEIA) (Abbott Laboratories) and (b) the Western Blot-HIV-1 (WB) (Cambridge Biotech Corporation) to confirm positive results with MEIA. Sera reactivity for HIV antibodies was 14.4%. The highest frequency of anti-HIV antibodies was found in the A and B maximum-security prisons: 17% and 21.5%, respectively. In prison C, the frequency of reagents was 10.9%. Seventy three inmates, initially negative in the MEIA test, were checked again five and seven months later. Three of them, all from the maximum-security facilities, became reactive in the MEIA test, with confirmation in the WB, suggesting that serological conversion had occurred after imprisonment.
Resumo:
The no-till system with complex cropping sequences may improve the structural quality and carbon (C) sequestration in soils of the tropics. Thus, the objective of this study was to evaluate the effects of cropping sequences after eight years under the no-till system on the physical properties and C sequestration in an Oxisol in the municipality of Jaboticabal, Sao Paulo, Brazil. A randomized split-block design with three replications was used. The treatments were combinations of three summer cropping sequences - corn/corn (Zea mays L.) (CC), soybean/soybean (Glycine max L. Merryll) (SS), and soybean-corn (SC); and seven winter crops - corn, sunflower (Helianthus annuus L.), oilseed radish (Raphanus sativus L.), pearl millet (Pennisetum americanum (L.) Leeke), pigeon pea (Cajanus cajan (L.) Millsp), grain sorghum (Sorghum bicolor (L.) Moench), and sunn hemp (Crotalaria juncea L.). Soil samples were taken at the 0-10 cm depth after eight years of experimentation. Soil under SC and CC had higher mean weight diameter (3.63 and 3.55 mm, respectively) and geometric mean diameter (3.55 and 2.92 mm) of the aggregates compared to soil under SS (3.18 and 2.46 mm). The CC resulted in the highest soil organic C content (17.07 g kg-1), soil C stock (15.70 Mg ha-1), and rate of C sequestration (0.70 Mg ha-1 yr-1) among the summer crops. Among the winter crops, soil under pigeon pea had the highest total porosity (0.50 m³ m-3), and that under sunn hemp had the highest water stable aggregates (93.74 %). In addition, sunn hemp did not differ from grain sorghum and contained the highest soil organic C content (16.82 g kg-1) and also had the highest rate of C sequestration (0.67 Mg ha-1 yr-1). The soil resistance to penetration was the lower limit of the least limiting water range, while the upper limit was air-filled porosity for soil bulk densities higher than 1.39 kg dm-3 for all cropping sequences. Within the SC sequence, soil under corn and pigeon pea increased least limiting water range by formation of biopores because soil resistance to penetration decreased with the increase in soil bulk density.
Resumo:
The objective of this work was to assess the effects of conventional tillage and of different direct seeding mulch-based cropping systems (DMC) on soil nematofauna characteristics. The long-term field experiment was carried out in the highlands of Madagascar on an andic Dystrustept soil. Soil samples were taken once a year during three successive years (14 to 16 years after installation of the treatments) from a 0-5-cm soil layer of a conventional tillage system and of three kinds of DMC: direct seeding on mulch from rotation soybean-maize residues; direct seeding of maize-maize rotation on living mulch of silverleaf (Desmodium uncinatum); direct seeding of bean (Phaseolus vulgaris)-soybean rotation on living mulch of kikuyu grass (Pennisetum clandestinum). The samples were compared with samples from natural fallows. The soil nematofauna, characterized by the abundance of different trophic groups and indices (MI, maturity index; EI and SI, enrichment and structure indices), allowed the discrimination of the different cropping systems. The different DMC treatments had a more complex soil food web than the tillage treatment: SI and MI were significantly greater in DMC systems. Moreover, DMC with dead mulch had a lower density of free-living nematodes than DMC with living mulch, which suggested a lower microbial activity.
Resumo:
Fabrication of new optical devices based upon the incorporation of rare earth ions via sol-gel methods depends on elimination of dopant ion clusters and residual hydroxyl groups from the final material. The optical absorption and/or luminescence properties of luminescent rare earth ions are influenced by the local bonding environment and the distribution of the rare-earth dopants in the matrix. Typically, dopants are incorporated into gel via dissolution of soluble species into the initial precursor sol. In this work, Eu3+ is used as optical probe, to assess changes in the local environment. Results of emission, excitation, fluorescence line narrowing and lifetimes studies of Eu3+-doped gels derived from Si(OCH3)4 and fluorinated/chelate Eu3+ precursors are presented. The precursors used in the sol-gel synthesis were: tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate) Eu(III), Eu (III) trifluoromethanesulfonate, Eu(III) acetylacetonate hydrate, Eu (III) trifluoroacetate trihidrate, tris (2,2,6,6-tetramethyl-3,5- heptanedionate) Eu(III) and Eu(NO3)3.6H2O. The results were interpreted in terms of the evolution of the Eu3+ fluorescence in systems varying from solution to the gels densified to 800ºC. The lifetimes studies indicate that the fluorinated precursors are effective at reducing the water content in densified gels.
Resumo:
Simulations have been carried out on the bromate - oxalic acid - Ce(IV) - acetone oscillating reaction, under flow conditions, using Field and Boyd's model (J. Phys. Chem. 1985, 89, 3707). Many different complex dynamic behaviors were found, including simple periodic oscillations, complex periodic oscillations, quasiperiodicity and chaos. Some of these complex oscillations can be understood as belonging to a Farey sequence. The many different behaviors were systematized in a phase diagram which shows that some regions of complex patterns were nested with one inside the other. The existence of almost all known dynamic behavior for this system allows the suggestion that it can be used as a model for some very complex phenomena that occur in biological systems.
Resumo:
Two simple sensitive and cost-effective spectrophotometric methods are described for the determination of lansoprazole (LPZ) in bulk drug and in capsules using ceric ammonium sulphate (CAS), iron (II), orthophenanthroline and thiocyanate as reagents. In both methods, an acidic solution of lansoprazole is treated with a measured excess of CAS followed by the determination of unreacted oxidant by two procedures involving different reaction schemes. The first method involves the reduction of residual oxidant by a known amount of iron(II), and the unreacted iron(II) is complexed with orthophenanthroline at a raised pH, and the absorbance of the resulting complex measured at 510 nm (method A). In the second method, the unreacted CAS is reduced by excess of iron (II), and the resulting iron (III) is complexed with thiocyanate in the acid medium and the absorbance of the complex measured at 470 nm (method B). In both methods, the amount CAS reacted corresponds to the amount of LPZ. In method A, the absorbance is found to increase linearly with the concentration of LPZ where as in method B a linear decrease in absorbance occurs. The systems obey Beer's law for 2.5-30 and 2.5-25 µg mL-1 for method A and method B, respectively, and the corresponding molar absorptivity values are 8.1×10³ and 1.5×10(4) L mol-1cm-1 . The methods were successfully applied to the determination of LPZ in capsules and the results tallied well with the label claim. No interference was observed from the concomitant substances normally added to capsules.
Resumo:
Two sensitive spectrophotometric methods are described for the determination of simvastatin (SMT) in bulk drug and in tablets. The methods are based on the oxidation of SMT by a measured excess of cerium (IV) in acid medium followed by determination of unreacted oxidant by two different reaction schemes. In one procedure (method A), the residual cerium (IV) is reacted with a fixed concentration of ferroin and the increase in absorbance is measured at 510 nm. The second approach (method B) involves the reduction of the unreacted cerium (IV) with a fixed quantity of iron (II), and the resulting iron (III) is complexed with thiocyanate and the absorbance measured at 470 nm. In both methods, the amount of cerium (IV) reacted corresponds to SMT concentration. The experimental conditions for both methods were optimized. In method A, the absorbance is found to increase linearly with SMT concentration (r = 0.9995) whereas in method B, the same decreased (r = -0.9943). The systems obey Beer's law for 0.6-7.5 and 0.5-5.0 µg mL-1 for method A and method B, respectively. The calculated molar absorptivity values are 2.7 X 10(4) and 1.06 X 10(5) Lmol-1 cm-1, respectively; and the corresponding sandel sensitivity values are 0.0153 and 0.0039µg cm-2, respectively. The limit of detection (LOD) and quantification (LOQ) are reported for both methods. Intra-day and inter-day precision, and accuracy of the methods were established as per the current ICH guidelines. The methods were successfully applied to the determination of SMT in tablets and the results were statistically compared with those of the reference method by applying the Student's t-test and F-test. No interference was observed from the common excipients added to tablets. The accuracy and validity of the methods were further ascertained by performing recovery experiments via standard addition procedure.
Resumo:
This study aimed to investigate the potential use of magnetic susceptibility (MS) as pedotransfer function to predict soil attributes under two sugarcane harvesting management systems. For each area of 1 ha (one with green sugarcane mechanized harvesting and other one with burnt sugarcane manual harvesting), 126 soil samples were collected and subjected to laboratory analysis to determine soil physical, chemical and mineralogical attributes and for measuring of MS. Data were submitted to descriptive statistics by calculating the mean and coefficient of variation. In order to compare the means in the different harvesting management systems it was carried out the Tukey test at a significance level of 5%. In order to investigate the correlation of the MS with other soil properties it was made the correlation test and aiming to assess how the MS contributes to the prediction of soil complex attributes it was made the multiple linear regressions. The results demonstrate that MS showed, in both sugarcane harvesting management systems, statistical correlation with chemical, physical and mineralogical soil attributes and it also showed potential to be used as pedotransfer function to predict attributes of the studied oxisol.