1,178 research outputs found

    Meshless methods in dual analysis: theoretical and implementation issues

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    This paper presents a meshless implementation of dual analysis for 2D linear elasticity problems. The derivation of the governing systems of equations for the discretized compatible and equilibrated models is detailed and crucial implementation issues of the proposed algorithm are discussed: (i) arising of deficiencies associated with the independent approximation field used for the imposition of the essential boundary conditions (EBC) for the two parts of the boundary sharing a corner and (ii) determination of the Lagrange multipliers functional space used to impose EBC. An attempt to implement the latter resulted in an approximation which is nothing more than the trace on the essential boundary of the domain nodal functions. The difficulties posed by such approximation are explained using the inf-sup condition.  Several examples of global (energy) and local (displacements) quantities of interest and theirs bounds determination are used to demonstrate the validity of the presented meshless approach to dual analysis. Numerical assessment of the convergence rates obtained for both models is made, for different polynomial basis degree

    Redundancy and error resilience in Boolean Networks

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    We consider the effect of noise in sparse Boolean Networks with redundant functions. We show that they always exhibit a non-zero error level, and the dynamics undergoes a phase transition from non-ergodicity to ergodicity, as a function of noise, after which the system is no longer capable of preserving a memory if its initial state. We obtain upper-bounds on the critical value of noise for networks of different sparsity.Comment: 4 pages, 5 figure

    Principal component analysis on recurrent venous thromboembolism

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    The rates of recurrent venous thromboembolism (RVTE) vary widely, and its causes still need to be elucidated. Statistical multivariate methods can be used to determine disease predictors and improve current methods for risk calculation. The objective of this study was to apply principal component analysis to a set of data containing clinical records of patients with previous venous thromboembolism and extract the main factors that predict recurrent thrombosis. Records of 39 factors including blood and lipid parameters, hereditary thrombophilia, antiphospholipid syndrome, clinical data regarding previous thrombosis and treatment, and Doppler ultrasound results were collected from 235 patients. The results showed that 13 principal components were associated with RVTE and that 18 of 39 factors are the important for the analysis. These factors include red blood cell, white blood cell, hematocrit, red cell distribution width, glucose, lipids, natural anticoagulant, creatinine, age, as well as first deep vein thrombosis data (distal/proximal, d-dimer, and time of anticoagulation). The results demonstrated that simple clinical parameters easy to be collected can be used to predict rates of recurrence and to develop new clinical decision support systems to predict the rates of RVTE25FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2016/14172-6The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Funded by Fundac¸a˜o de Amparo `a Pesquisa do Estado de Sa˜o Paulo (FAPESP). Process number: 2016/14172-

    Support for automatic refactoring of business logic

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    Software’s structure profoundly affects its development and maintenance costs. Poor software’s structure may lead to well-known design flaws, such as large modules or long methods. A possible ap- proach to reduce a module’s complexity is the Extract Method refactor- ing technique. This technique allows the decomposition of a large and complex method into smaller and simpler ones, while reducing the orig- inal method’s size and improving its readability and comprehension. The OutSystems platform is a low-code platform that allows the de- velopment of web and mobile applications that rely on a set of visual Domain-Specific Languages (DSLs). Even low-code languages when im- properly used can lead to software that has maintenance issues like long methods. Thus, the purpose of this paper is to present the research and devel- opment done to provide the OutSystems platform with a tool that au- tomatically suggests Extract Method refactoring opportunities. The re- search combines program slicing techniques with code complexity metrics to calculate the best refactoring opportunities that preserve programs’ functionality. The proposed approach was tested on typical OutSystems apps and was shown to be able to reduce the overall applications’ complexity.info:eu-repo/semantics/publishedVersio

    Diversity and genetic structure of the native Brazil nut tree (Bertholletia excelsa Bonpl.) population.

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    The present study was carried out in a native Brazil nut tree population (Bertholletia excelsa Bonpl., Lecythidaceae) to assess its genetic diversity and structure. Ten microsatellite markers were used to genotype 198 adult trees (B. excelsa). The population presented high genetic diversity and inbreeding absence rates. The empirical Bayesian method showed three distinct groups in the structure of this population. Molecular analysis of variance showed 98% variability within groups, and 2% between groups. The genetic divergence (FST) indicated little difference between groups; thus, suggesting efficient gene flow between the analyzed B. excelsa adult trees

    An empirical evaluation of imputation accuracy for association statistics reveals increased type-I error rates in genome-wide associations

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    <p>Abstract</p> <p>Background</p> <p>Genome wide association studies (GWAS) are becoming the approach of choice to identify genetic determinants of complex phenotypes and common diseases. The astonishing amount of generated data and the use of distinct genotyping platforms with variable genomic coverage are still analytical challenges. Imputation algorithms combine directly genotyped markers information with haplotypic structure for the population of interest for the inference of a badly genotyped or missing marker and are considered a near zero cost approach to allow the comparison and combination of data generated in different studies. Several reports stated that imputed markers have an overall acceptable accuracy but no published report has performed a pair wise comparison of imputed and empiric association statistics of a complete set of GWAS markers.</p> <p>Results</p> <p>In this report we identified a total of 73 imputed markers that yielded a nominally statistically significant association at <it>P </it>< 10 <sup>-5 </sup>for type 2 Diabetes Mellitus and compared them with results obtained based on empirical allelic frequencies. Interestingly, despite their overall high correlation, association statistics based on imputed frequencies were discordant in 35 of the 73 (47%) associated markers, considerably inflating the type I error rate of imputed markers. We comprehensively tested several quality thresholds, the haplotypic structure underlying imputed markers and the use of flanking markers as predictors of inaccurate association statistics derived from imputed markers.</p> <p>Conclusions</p> <p>Our results suggest that association statistics from imputed markers showing specific MAF (Minor Allele Frequencies) range, located in weak linkage disequilibrium blocks or strongly deviating from local patterns of association are prone to have inflated false positive association signals. The present study highlights the potential of imputation procedures and proposes simple procedures for selecting the best imputed markers for follow-up genotyping studies.</p

    Rammed earth: feasibility of a global concept applied locally

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    Rammed earth is an ancient building technique that has been continuously reinvented in the dynamic movement of people all over the world, where it has been used to build from dwellings to enormous fortresses and city walls. In the particular case of Portugal, the inhabitants have been closely related to earth construction. From one region to another, rammed earth, adobe and wattle-and-daub buildings are frequently found. The rammed earth construction is mainly found in the southern part of Portugal and is almost absent from the north. However, the relatively low seismic hazard of the north of Portugal plus the sustainability of earth as a building material encourages the development of this technique in the region. The suitability of the typical granite residual soils from the Minho region for rammed earth construction was assessed by means of an experimental program, in which three representative soils were subjected to expeditious and laboratory tests that evaluated the characteristics of the soils and the performance of rammed earth built with them. The results showed that the granite residual soils tested fulfil most of the requirements needed for rammed earth construction, being the low compressive strength its main limitation. In this way, an innovative and sustainable stabilization technique based on alkaline activation of fly ash is proposed

    Molecular Interactions in Ionic Liquids: The NMR Contribution towards Tailored Solvents

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    Ionic liquids have been on the spotlight of chemical research field in the last decades. Their physical properties (low vapor pressure, thermal stability, and conductivity) and the possibility of fine tuning make them a versatile class of compounds for a wide range of applications, such as catalysis, energy, and material sciences. Ionic liquids can establish multiple intermolecular interactions with solutes such as electrostatic, van der Waals, or hydrogen bonds. The prospect of designing ionic liquid structures toward specific applications has attracted the attention to these alternative solvents. However, their rational design demands a molecular detailed view, and Nuclear Magnetic Resonance is a unique and privileged technique for this purpose, as it provides atomic resolution and at the same time enables the study of dynamic information. In this chapter, we provide an overview about the application of Nuclear Magnetic Resonance spectroscopy techniques as a methodology for the rational design of ionic liquids as solvents for small organic compounds, CO2 capture, and polymers such as cellulose focusing mainly in the last 10 years

    Rammed earth construction with granitic residual soils: the case study of northern Portugal

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    Building in unstabilised rammed earth results in low environmental impact. However, northern Portugal has not historical tradition with this technique, and thus the suitability of the local granitic residual soils is unknown. This paper presents an experimental investigation, where this possibility is assessed. The results showed that these soils are unsuitable, and that rammed earth construction is only feasible if these soils go through a stabilising process. The alkaline activation of fly ash was investigated as an environmentally friendly stabilisation technique, and it proved to be capable of improving the performance of rammed earth

    On the use of organic semiconductors as handles for optical tweezers experiments: trapping and manipulating polyaniline (PANI) microparticles

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    Here we propose the use of the organic semiconductor polyaniline (PANI) for the preparation of spherical-shaped microparticles to serve as handles in optical tweezers (OT) experiments. The stable trapping and manipulation of PANI beads was demonstrated for the first time, using a Gaussian (TEM00TEM_{00}) beam optical tweezers. The trap stiffness was characterized for various different parameters such as the bead radius, the laser power and the distance between the bead and the coverslip of the sample chamber, attesting the viability of using such material for optical manipulation. Since the effective optical properties of PANI can be modulated by the synthesis process, new related applications are also proposed. The results of the present work therefore open the door for using semiconductor polymeric materials in OT applications.Comment: 10 pages and 5 figure
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