864 resultados para Hierarchy problem
Resumo:
The The The The growing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demandgrowing demand for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of for the expansion of the the the the publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system publicly funded system of education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goodof education as merit and free goods emphasized emphasized emphasized emphasized emphasized emphasized emphasized emphasized emphasized emphasized on large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation large allocation of funds on of funds on of funds on of funds on of funds on of funds on of funds on of funds on of funds on of funds on of funds for promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting educationfor promoting education. Compared to . Compared to . Compared to . Compared to . Compared to . Compared to . Compared to . Compared to . Compared to . Compared to . Compared to . Compared to . Compared to the rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of Indiathe rest of India, Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead , Kerala is far ahead in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect in this respect primarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the eprimarily because of the earlierarlierarlierarlierarlierarlier political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social political and social compulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions ofcompulsions of the state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The prethe state. The presumption of sumption of sumption of sumption of sumption of sumption of sumption of sumption of sumption of sumption of sumption of assured assured assured assured assured assured assured assured and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed and guaranteed employment in employment in employment in employment in employment in employment in employment in employment in employment in employment in employment in employment in the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East the Middle East and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other and also in other countries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased furthecountries increased further the scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher educationthe scope of higher education in KeralaKeralaKeralaKeralaKeralaKerala, particularparticularparticularparticularparticularparticularparticularparticularparticularparticularly the technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe technical educationthe
Resumo:
This paper re-addresses the issue of a lacking genuine design research paradigm. It tries to sketch an operational model of such a paradigm, based upon a generic design process model, which is derived from basic notions of evolution and learning in different domains of knowing (and turns out to be not very different from existing ones). It does not abandon the scientific paradigm but concludes that the latter has to be embedded into / subordinated under a design paradigm.
Resumo:
Soil organic matter (SOM) vitally impacts all soil functions and plays a key role in the global carbon (C) cycle. More than 70% of the terrestric C stocks that participate in the active C cycle are stored in the soil. Therefore, quantitative knowledge of the rates of C incorporation into SOM fractions of different residence time is crucial to understand and predict the sequestration and stabilization of soil organic carbon (SOC). Consequently, there is a need of fractionation procedures that are capable of isolating functionally SOM fractions, i.e. fractions that are defined by their stability. The literature generally refers to three main mechanisms of SOM stabilization: protection of SOM from decomposition by (i) its structural composition, i.e. recalcitrance, (ii) spatial inaccessibility and/or (iii) interaction with soil minerals and metal ions. One of the difficulties in developing fractionation procedures for the isolation of functional SOM fractions is the marked heterogeneity of the soil environment with its various stabilization mechanisms – often several mechanisms operating simultaneously – in soils and soil horizons of different texture and mineralogy. The overall objective of the present thesis was to evaluate present fractionation techniques and to get a better understanding of the factors of SOM sequestration and stabilization. The first part of this study is attended to the structural composition of SOM. Using 13C cross-polarization magic-angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, (i) the effect of land use on SOM composition was investigated and (ii) examined whether SOM composition contributes to the different stability of SOM in density and aggregate fractions. The second part of the present work deals with the mineral-associated SOM fraction. The aim was (iii) to evaluate the suitability of chemical fractionation procedures used in the literature for the isolation of stable SOM pools (stepwise hydrolysis, treatments using oxidizing agents like Na2S2O8, H2O2, and NaOCl as well as demineralization of the residue obtained by the NaOCl treatment using HF (NaOCl+HF)) by pool sizes, 13C and 14C data. Further, (iv) the isolated SOM fractions were compared to the inert organic matter (IOM) pool obtained for the investigated soils using the Rothamsted Carbon Model and isotope data in order to see whether the tested chemical fractionation methods produce SOM fractions capable to represent this pool. Besides chemical fractionation, (v) the suitability of thermal oxidation at different temperatures for obtaining stable SOC pools was evaluated. Finally, (vi) the short-term aggregate dynamics and the factors that impact macroaggregate formation and C stabilization were investigated by means of an incubation study using treatments with and without application of 15N labeled maize straw of different degradability (leaves and coarse roots). All treatments were conducted with and without the addition of fungicide. Two study sites with different soil properties and land managements were chosen for these investigations. The first one, located at Rotthalmünster, is a Stagnic Luvisol (silty loam) under different land use regimes. The Ah horizons of a spruce forest and continuous grassland and the Ap and E horizons of two plots with arable crops (continuous maize and wheat cropping) were examined. The soil of the second study site, located at Halle, is a Haplic Phaeozem (loamy sand) where the Ap horizons of two plots with arable crops (continuous maize and rye cropping) were investigated. Both study sites had a C3-/C4-vegetational change on the maize plot for the purpose of tracing the incorporation of the younger, maize-derived C into different SOM fractions and the calculation of apparent C turnover times of these. The Halle site is located near a train station and industrial areas, which caused a contamination with high amounts of fossil C. The investigation of aggregate and density fractions by 13C CPMAS NMR spectroscopy revealed that density fractionation isolated SOM fractions of different composition. The consumption of a considerable part (10–20%) of the easily available O-alkyl-C and the selective preservation of the more recalcitrant alkyl-C when passing from litter to the different particulate organic matter (POM) fractions suggest that density fractionation was able to isolate SOM fractions with different degrees of decomposition. The spectra of the aggregate fractions resembled those of the mineral-associated SOM fraction obtained by density fractionation and no considerable differences were observed between aggregate size classes. Comparison of plant litter, density and aggregate size fractions from soil under different land use showed that the type of land use markedly influenced the composition of SOM. While SOM of the acid forest soil was characterized by a large content (> 50%) of POM, which contained high amounts of spruce-litter derived alkyl-C, the organic matter in the biologically more active grassland and arable soils was dominated by mineral-associated SOM (> 95%). This SOM fraction comprised greater proportions of aryl- and carbonyl-C and is considered to contain a higher amount of microbially-derived organic substances. Land use can alter both, structure and stability of SOM fractions. All applied chemical treatments induced considerable SOC losses (> 70–95% of mineral-associated SOM) in the investigated soils. The proportion of residual C after chemical fractionation was largest in the arable Ap and E horizons and increased with decreasing C content in the initial SOC after stepwise hydrolysis as well as after the oxidative treatments with H2O2 and Na2S2O8. This can be expected for a functional stable pool of SOM, because it is assumed that the more easily available part of SOC is consumed first if C inputs decrease. All chemical treatments led to a preferential loss of the younger, maize-derived SOC, but this was most pronounced after the treatments with Na2S2O8 and H2O2. After all chemical fractionations, the mean 14C ages of SOC were higher than in the mineral-associated SOM fraction for both study sites and increased in the order: NaOCl < NaOCl+HF ≤ stepwise hydrolysis << H2O2 ≈ Na2S2O8. The results suggest that all treatments were capable of isolating a more stable SOM fraction, but the treatments with H2O2 and Na2S2O8 were the most efficient ones. However, none of the chemical fractionation methods was able to fit the IOM pool calculated using the Rothamsted Carbon Model and isotope data. In the evaluation of thermal oxidation for obtaining stable C fractions, SOC losses increased with temperature from 24–48% (200°C) to 100% (500°C). In the Halle maize Ap horizon, losses of the young, maize-derived C were considerably higher than losses of the older C3-derived C, leading to an increase in the apparent C turnover time from 220 years in mineral-associated SOC to 1158 years after thermal oxidation at 300°C. Most likely, the preferential loss of maize-derived C in the Halle soil was caused by the presence of the high amounts of fossil C mentioned above, which make up a relatively large thermally stable C3-C pool in this soil. This agrees with lower overall SOC losses for the Halle Ap horizon compared to the Rotthalmünster Ap horizon. In the Rotthalmünster soil only slightly more maize-derived than C3-derived SOC was removed by thermal oxidation. Apparent C turnover times increased slightly from 58 years in mineral-associated SOC to 77 years after thermal oxidation at 300°C in the Rotthalmünster Ap and from 151 to 247 years in the Rotthalmünster E horizon. This led to the conclusion that thermal oxidation of SOM was not capable of isolating SOM fractions of considerably higher stability. The incubation experiment showed that macroaggregates develop rapidly after the addition of easily available plant residues. Within the first four weeks of incubation, the maximum aggregation was reached in all treatments without addition of fungicide. The formation of water-stable macroaggregates was related to the size of the microbial biomass pool and its activity. Furthermore, fungi were found to be crucial for the development of soil macroaggregates as the formation of water-stable macroaggregates was significantly delayed in the fungicide treated soils. The C concentration in the obtained aggregate fractions decreased with decreasing aggregate size class, which is in line with the aggregate hierarchy postulated by several authors for soils with SOM as the major binding agent. Macroaggregation involved incorporation of large amounts maize-derived organic matter, but macroaggregates did not play the most important role in the stabilization of maize-derived SOM, because of their relatively low amount (less than 10% of the soil mass). Furthermore, the maize-derived organic matter was quickly incorporated into all aggregate size classes. The microaggregate fraction stored the largest quantities of maize-derived C and N – up to 70% of the residual maize-C and -N were stored in this fraction.
Resumo:
Quasi-molecular X-rays observed in heavy ion collisions are interpreted within a relativistic calculation of correlation diagrams using the Dirac-Slater model. A semiquantitative description of noncharacteristic M X rays is given for the system Au-I.
Resumo:
The aim of this paper is the numerical treatment of a boundary value problem for the system of Stokes' equations. For this we extend the method of approximate approximations to boundary value problems. This method was introduced by V. Maz'ya in 1991 and has been used until now for the approximation of smooth functions defined on the whole space and for the approximation of volume potentials. In the present paper we develop an approximation procedure for the solution of the interior Dirichlet problem for the system of Stokes' equations in two dimensions. The procedure is based on potential theoretical considerations in connection with a boundary integral equations method and consists of three approximation steps as follows. In a first step the unknown source density in the potential representation of the solution is replaced by approximate approximations. In a second step the decay behavior of the generating functions is used to gain a suitable approximation for the potential kernel, and in a third step Nyström's method leads to a linear algebraic system for the approximate source density. For every step a convergence analysis is established and corresponding error estimates are given.
Resumo:
The paper will consist of three parts. In part I we shall present some background considerations which are necessary as a basis for what follows. We shall try to clarify some basic concepts and notions, and we shall collect the most important arguments (and related goals) in favour of problem solving, modelling and applications to other subjects in mathematics instruction. In the main part II we shall review the present state, recent trends, and prospective lines of development, both in empirical or theoretical research and in the practice of mathematics instruction and mathematics education, concerning problem solving, modelling, applications and relations to other subjects. In particular, we shall identify and discuss four major trends: a widened spectrum of arguments, an increased globality, an increased unification, and an extended use of computers. In the final part III we shall comment upon some important issues and problems related to our topic.
Resumo:
The paper will consist of three parts. In part I we shall present some background considerations which are necessary as a basis for what follows. We shall try to clarify some basic concepts and notions, and we shall collect the most important arguments (and related goals) in favour of problem solving, modelling and applications to other subjects in mathematics instruction. In the main part II we shall review the present state, recent trends, and prospective lines of development, both in empirical or theoretical research and in the practice of mathematics instruction and mathematics education, concerning (applied) problem solving, modelling, applications and relations to other subjects. In particular, we shall identify and discuss four major trends: a widened spectrum of arguments, an increased globality, an increased unification, and an extended use of computers. In the final part III we shall comment upon some important issues and problems related to our topic.
Resumo:
'The problem of the graphic artist' is a small example of applying elementary mathematics (divisibility of natural numbers) to a real problem which we ourselves have actually experienced. It deals with the possibilities for partitioning a sheet of paper into strips. In this contribution we report on a teaching unit in grade 6 as well as on informal tests with students in school and university. Finally we analyse this example methodologically, summarise our observations with pupils and students, and draw some didactical conclusions.
Resumo:
Cubicle should provide good resting comfort as well as clean udders. Dairy cows in cubicle houses often face a restrictive environment with regard to resting behaviour, whereas cleanliness may still be impaired. This study aimed to determine reliable behavioural measures regarding resting comfort applicable in on-farm welfare assessments. Furthermore, relationships between cubicle design, cow sizes, management factors and udder cleanliness (namely teats and teat tips) were investigated. Altogether 15 resting measures were examined in terms of feasibility, inter-observer reliability (IOR) and consistency of results per farm over time. They were recorded during three farm visits on farms in Germany and Austria with cubicle, deep litter and tie stall systems. Seven measures occurred to infrequently to allow reliable recording within a limited observation time. IOR was generally acceptable to excellent except for 'collisions during lying down', which only showed good IOR after improvement of the definition. Only three measures were acceptably repeatable over time: 'duration of lying down', 'percentage of collisions during lying down' and 'percentage of cows lying partly or completely outside lying area'. These measures were evaluated as suitable animal based welfare measures regarding resting behaviour in the framework of an on-farm welfare assessment protocol. The second part of the thesis comprises a cross-sectional study on resting comfort and cow cleanliness including 23 Holstein Friesian dairy herds with very low within-farm variation in cubicle measures. Height at withers, shoulder width and diagonal body length were measured in 79-100 % of the cows (herd size 30 to115 cows). Based on the 25 % largest animals, compliance with recommendations for cubicle measures was calculated. Cleanliness of different body parts, the udder, teats and teat tips was assessed for each cow in the herd prior to morning milking. No significant correlation was found between udder soiling and teat or teat tip soiling on herd level. The final model of a stepwise regression regarding the percentage of dirty teats per farm explained 58.5 % the variance and contained four factors. Teat dipping after milking which might be associated with an overall clean and accurate management style, deep bedded cubicles, increasing cubicle maintenance times and decreasing compliance concerning total cubicle length predicted lower teat soiling. The final model concerning teat tip soiling explained 46.0 % of the variance and contained three factors. Increasing litter height in the rear part of the cubicle and increased alley soiling which is difficult to explain, predicted for less soiled teat tips, whereas increasing compliance concerning resting length was associated with higher percentages of dirty teat tips. The dependent variable ‘duration of lying down’ was analysed using again stepwise regression. The final model explained 54.8 % of the total variance. Lying down duration was significantly shorter in deep bedded cubicles. Further explanatory though not significant factors in the model were neck-rail height, deep bedding or comfort mattresses versus concrete floor or rubber mats and clearance height of side partitions. In the attempt to create a more comprehensive lying down measure, another analysis was carried out with percentage of ‘impaired lying down’ (i.e. events exceeding 6.3 seconds, with collisions or being interrupted) as dependent variable. The explanatory value of this final model was 41.3 %. An increase in partition length, in compliance concerning cubicle width and the presence of straw within bedding predicted a lower proportion of impaired lying down. The effect of partition length is difficult to interpret, but partition length and height were positively correlated on the study farms, possibly leading to a bigger zone of clear space for pelvis freedom. No associations could be found between impaired lying down and teat or teat tip soiling. Altogether, in agreement with earlier studies it was found that cubicle dimensions in practice are often inadequate with regard to the body dimensions of the cows, leading to high proportions of impaired lying down behaviour, whereas teat cleanliness is still unsatisfactory. Connections between cleanliness and cow comfort are far from simplistic. Especially the relationship between cubicle characteristics and lying down behaviour apparently is very complex, so that it is difficult to identify single influential factors that are valid for all farm situations. However, based on the results of the present study the use of deep bedded cubicles can be recommended as well as improved management with special regard to cubicle and litter maintenance in order to achieve both better resting comfort and teat cleanliness.