2,975 research outputs found
Terrain classification by cluster analisys
The digital terrain modelling can be obtained by different methods belonging to two principal categories: deterministic methods (e.g. polinomial and spline functions interpolation, Fourier spectra) and stochastic methods (e.g. least squares collocation and fractals, i.e. the concept of selfsimilarity in probability).
To reach good resul ts, both the fi rst and the second methods need same initial suitable information which can be gained by a preprocessing of data named terrain classification.
In fact, the deterministic methods require to know how is the roughness of the terrain, related to the density of the data (elevations, deformations, etc.) used for the i nterpo 1 at ion, and the stochast i c methods ask for the knowledge of the autocorrelation function of the data.
Moreover, may be useful or very necessary to sp 1 it up the area under consideration in subareas homogeneous according to some parameters, because of different kinds of reasons (too much large initial set of data, so that they can't be processed togheter; very important discontinuities or singularities; etc.).
Last but not least, may be remarkable to test the type of distribution (normal or non-normal) of the subsets obtained by the preceding selection, because the statistical properties of the normal distribution are very important (e.g., least squares linear estimations are the same of maximum likelihood and minimum variance ones)
Qualitative and quantitative analysis of mixtures of compounds containing both hydrogen and deuterium
Method allows qualitative and quantitative analysis of mixtures of partially deuterated compounds. Nuclear magnetic resonance spectroscopy determines location and amount of deuterium in organic compounds but not fully deuterated compounds. Mass spectroscopy can detect fully deuterated species but not the location
Import demand of Bananas in the European Union
The EU banana market has been of enormous interest for researchers for a long time, especially after the import policy unification brought by the Common Market Organization for Bananas (CMOB) in 1993. Empirical evidence suggests that the CMOB and its subsequent modifications have been highly distorting. However, the quantifications made of those distortions by different authors vary a lot, not only in magnitude but also in direction. The reason is that for each evaluation, a different system of demand equations has been estimated. However, besides the different models used, there is one common denominator to all models. They do not incorporate the general restrictions (homogeneity, symmetry and adding up) necessary to make the demand estimations consistent with economic theory. In this paper we estimate the almost ideal demand system (AIDS) to calculate more reliable elasticities to facilitate future welfare analysis of the EU banana market. The inverse almost ideal demand system (IAIDS) was also estimated under the alternative assumption that import prices adjust to quantities instead to quantities adjusting to price variations as it has usually assumed. However, the results are not reported because due to the upcoming import policy and its subsequent quota elimination, quantities will not longer be predetermined. Preliminary results show that demand elasticities are different depending on the region of origin of the imported bananas. Latin American bananas are substitutes of bananas from preferred suppliers and complements of others while imports from the ACP are substitutes of all regions. EU bananas behave similar to Latin American in the sense that they are substitutes of all by other suppliers. Preliminary welfare analysis of the proposed policy shows that both Latin American producers and EU consumers of Latin American bananas will lost from the quota elimination and increase in the tariff level.International Relations/Trade,
Multivariate AIM Consumer Demand Model Applied to Dried Fruit, Raisins, and Dried Plums
Abstract: We estimate a semi-nonparametric demand system based on a multivariate version of the Muntz-Szatz series expansion which is called the Asymptotically Ideal Model (AIM). The model is applied to consumer demand for dried fruits, raisins, and dried plums. Results from the first and second order AIM expansions suggest that the second order expansion leads to a more economically consistent model, but the likelihood ratio test indicates the AIM(2) model was not a statistical improvement over the AIM(1) model.demand, consumers, AIM, Demand and Price Analysis,
Polarization entangled state measurement on a chip
The emerging strategy to overcome the limitations of bulk quantum optics
consists of taking advantage of the robustness and compactness achievable by
the integrated waveguide technology. Here we report the realization of a
directional coupler, fabricated by femtosecond laser waveguide writing, acting
as an integrated beam splitter able to support polarization encoded qubits.
This maskless and single step technique allows to realize circular transverse
waveguide profiles able to support the propagation of Gaussian modes with any
polarization state. Using this device, we demonstrate the quantum interference
with polarization entangled states and singlet state projection.Comment: Revtex, 5+2 pages (with supplementary information), 4+1 figure
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The role of dwelling type when estimating the effect of magnetic fields on childhood leukemia in the California Power Line Study (CAPS).
PurposeThe type of dwelling where a child lives is an important factor when considering residential exposure to environmental agents. In this paper, we explore its role when estimating the potential effects of magnetic fields (MF) on leukemia using data from the California Power Line Study (CAPS). In this context, dwelling type could be a risk factor, a proxy for other risk factors, a cause of MF exposure, a confounder, an effect-measure modifier, or some combination.MethodsWe obtained information on type of dwelling at birth on over 2,000 subjects. Using multivariable-adjusted logistic regression, we assessed whether dwelling type was a risk factor for childhood leukemia, which covariates and MF exposures were associated with dwelling type, and whether dwelling type was a potential confounder or an effect-measure modifier in the MF-leukemia relationship under the assumption of no-uncontrolled confounding.ResultsA majority of children lived in single-family homes or duplexes (70%). Dwelling type was associated with race/ethnicity and socioeconomic status but not with childhood leukemia risk, after other adjustments, and did not alter the MF-leukemia relationship upon adjustment as a potential confounder. Stratification revealed potential effect-measure modification by dwelling type on the multiplicative scale.ConclusionDwelling type does not appear to play a significant role in the MF-leukemia relationship in the CAPS dataset as a leukemia risk factor or confounder. Future research should explore the role of dwelling as an effect-measure modifier of the MF-leukemia association
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Organizational readiness for wellness promotion - a survey of 100 African American church leaders in South Los Angeles.
BackgroundChurches are an important asset and a trusted resource in the African American community. We needed a better understanding of their readiness to engage in health promotion before launching a large-scale health promotion effort in partnership with South Los Angeles churches.MethodsIn 2017, we conducted surveys with leaders of 100 churches. Surveys were conducted face-to-face (32%) or by telephone (68%) with senior pastors (one per church) and lasted on average 48βmin. We compared small (less than 50 active members), medium (50-99 active members) and large churches (at least 100 active members), and assessed which church characteristics were associated with the implementation of wellness activities.ResultsMedium and large churches conducted significantly more wellness activities than small churches and were more likely to have wellness champions and health policies. Regardless of church size, insufficient budget was the most commonly cited barrier to implement wellness activities (85%). A substantial proportion of churches was not sure how to implement wellness activities (61%) and lacked volunteers (58%). Forty-five percent of the variation in the number of wellness activities in the last 12βmonths was explained by church characteristics, such as size of congregation, number of paid staff, leadership engagement, having a wellness ministry and barriers.ConclusionsMany churches in South Los Angeles are actively engaged in health promotion activities, despite a general lack of resources. We recommend a comprehensive assessment of church characteristics in intervention studies to enable the use of strategies (e.g., stratification by size) that reduce imbalances that could mask or magnify study outcomes. Our data provide empirical support for the inner settings construct of the Consolidated Framework for Implementation Research in the context of health promotion in African American churches
The renovation of Santa Maria di Collemaggio Basilica: the intervention on the naveβs columns
The earthquake of LβAquila in 2009 caused the partial collapse of the S. Maria di Collemaggio Basilica. The XIII century naveβs columns showed serious cracking throughout their height. Therefore, a retrofitting intervention was planned with the purpose of protecting these valuable elements from future additional damages. The intervention designed involved the complete unloading and reloading of the columns. To avoid additional damages, it was necessary to verify that the procedure would not alter significantly the existing stress state and would not lead to the occurrence of tensile stresses greater than the materialsβ tensile strength. Therefore, a 3D FE model of the colonnade and the supported wall has been realized and a construction stage non-linear analysis implemented. The geometry was modeled through the acquisition of the results of a laser scanner survey in order to reflect faithfully the Basilicaβs irregularities (lack of verticality of the wall, eccentricities, different dimensions from one column to the other). Moreover, elastic-brittle constitutive laws were assigned to the modelβs materials to reproduce the intrinsic non-linearity of the masonry. The analysis results in terms of stresses and displacements were attentively analyzed. Furthermore, a comparison between the numerical results and the values measured during the intervention has been executed. An acceptable deviation between the values was observed and, therefore, the reliability of the model was assured
Formal Languages and Compilation
This textbook describes the essential principles and methods used for defining the syntax of artificial languages, and for designing efficient parsing algorithms and syntax-directed translators with semantic attributes. A comprehensive selection of topics is presented within a rigorous, unified framework, illustrated by numerous practical examples. Features and topics: presents a novel conceptual approach to parsing algorithms that applies to extended BNF grammars, together with a parallel parsing algorithm; supplies supplementary teaching tools, including course slides and exercises with solutions, at an associated website; unifies the concepts and notations used in different approaches, enabling an extended coverage of methods with a reduced number of definitions; systematically discusses ambiguous forms, allowing readers to avoid pitfalls when designing grammars; describes all algorithms in pseudocode, so that detailed knowledge of a specific programming language is not necessary; makes extensive usage of theoretical models of automata, transducers and formal grammars; includes concise coverage of algorithms for processing regular expressions and finite automata; and introduces static program analysis based on flow equations. This clearly-written, classroom-tested textbook is an ideal guide to the fundamentals of this field for advanced undergraduate and graduate students in computer science and computer engineering. Some background in programming is required, and readers should also be familiar with basic set theory, algebra and logic
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