286 research outputs found
Desempenho acad?mico de alunos de 9? ano na Geometria Espacial: impacto de vari?veis pessoal e de contexto
This article presents and discusses results from a study investigating the quality of Spatial Geometry academic performance of 9th grade students when they are about to be exposed to more complex concepts, geometric solids, and related problems in curricular learning experiences. Participants were Portuguese public school students. We also collected information about previous mathematics grades and mother?s schooling. A geometry test, a causal attribution to a school achievement test, and two reasoning tests ? spatial and mechanical ? were applied, and all collected data was statistically analysed and interpreted. To address the different nature of variables, we conducted a hierarchical linear regression. Results suggest that nearly 41% of variance on Spatial Geometry academic performance can be explained by the personal and contextual variables studied. The recommendation to schoolteachers involves designing learning experiences that engage students in spatial reasoning and high-order thinking skills.AF10-A514-BE72 | Luciana Pereira de BritoN/
Seismic analysis of a Mexican viaduct with nonlinear modeling of soil-structure interaction
Every day the need to understand earthquakes and how that phenomenon affects construction grows, to make it possible to prevent and minimize inherent risks to their relation. That need increases when projects are located in regions with large seismicity. Therefore, the present paper, which was developed in partnership with GEG ? Gabinete de Estruturas e Geotecnia, has, as a final goal, to study and compare the variety of calculation methods available on Eurocode 8 to design and evaluate earthquake resistant structures, using a real case study. The methods approached are linear dynamic analysis, also known as spectral analysis, nonlinear static analysis, also recognized as pushover analysis, and non-linear dynamic analysis, well-known as time-history analysis. Simultaneously to the seismic analyses, it is developed a detailed study of the parameters that affect the damping of soil-structure interaction.6612-034D-AE05 | PEDRO DA SILVA DELGADON/
Overstrength factors of RC bridges supported on single and multi-column RC piers in Mexico
Mexico highway network has more than 14,000 bridges. Most of them are reinforced concrete (RC) structures. The bridges design process incorporates the use of an overstrength factor that is not justified and has received little attention in published works. Mexican regulations allow using an overstrength factor for buildings in the range of 2?3, to reduce the design spectra as a function of the selected seismic behavior factor. However, for bridges, a single factor of 1.5 is proposed independent of any design parameter. The bridges in Mexico are mostly simply supported structures with maximum span lengths of 50 m. A relevant and distinctive aspect of the bridges designed in Mexico is the large load amplitudes
of the trucks used to define the live load and the high seismic activity in the country. This study determines overstrength factors of a family of medium-length RC bridges composed of simply supported superstructures and substructure made up of single and multi-column RC piers. Non-linear dynamic analyzes using a set of 80 accelerograms were carried out. The results show that the height of the
bridges and their seismic location are relevant parameters in the overstrength of the structures. Finally, analytical expressions are proposed to assess the overstrength factors of a very common bridge typology in Mexico and the world.6612-034D-AE05 | PEDRO DA SILVA DELGADON/
Earthquake source effect and impact of the applied methodology to assess the overstrength factors of RC bridges
Seismic hazard assessment in several sites worldwide depends on two or more seismic sources. Many countries affected by subduction zones have strong motions earthquakes originated in at least two important seismic sources. In Mexico, interplate earthquakes (subduction process) have epicenters located in the Pacific coast with hypocenter depths less than 45 km and intraplate earthquakes (intermediate-depth earthquakes) normally have epicenters inside the continent with depth hypocenters greater than 45 km. Both seismic sources can potentially produce events with magnitudes Mw greater than 8.0 and, therefore, generate severe damage to the country's infrastructure. The design process of the bridges in Mexico is based on the chapter of Seismic Design of the Manual of Civil Structures of the Federal Electricity Commission. The standard allows to reduce the spectral ordinates of the design spectra by ductility and overstrength. It establishes an overstrength factor of 1.5 to reduce the design spectra, value not well supported by the Manual. This study evaluates the effect of the seismic source and methodology used to compute overstrength factors of common typologies of reinforced concrete bridges. The seismic capacity of the bridges was calculated with nonlinear static analysis and nonlinear time history analysis. The results showed that the importance of the seismic source on the overstrength factors depends on the seismic location of the bridges and, in general terms, nonlinear static analysis overestimates the bridges overstrength.6612-034D-AE05 | PEDRO DA SILVA DELGADON/
The benefits of theory for clinical practice:Cognitive treatment for chronic low back pain patients as an illustrative example
Purpose. To demonstrate, with the help of an example of cognitive treatment for patients with chronic low back pain, how a systematic description of the content and theoretical underpinnings of treatment can help to improve clinical practice. Methods. A conceptual analysis, two types of theories, and a programme-theory framework were instrumental in systematically specifying the content of the treatment and the underlying assumptions. Results. A detailed description of the cognitive treatment, including: (i) The intended outcomes; (ii) the related treatment components; (iii) the therapeutic process that is expected to mediate between outcomes and components, (iv) the conditions for optimal application; and (v) the guiding principles. Conclusions. The systematic description of the treatment revealed important issues for clinical practice, such as the patient and therapist characteristics that are needed for optimal provision of cognitive treatment. The discussions on the role of theory in rehabilitation practice are taken one step further in this clinical commentary: instead of simply describing the problems, we also demonstrated a means to tackle them
Sedentary behaviour impairs skeletal muscle repair modulating the inflammatory response
This study investigated whether sedentary behaviour modulates skeletal-muscle repair and tissue inflammatory response after cardiotoxin (CTX)-induced injury. Singly caged rats spent 8 weeks either as a sedentary group (SED, n = 15) or as a control group (EX, n = 15)?caged with running wheels for voluntary running. All rats had each tibial anterior muscle infused either with CTX (CTX; right muscle) or saline solution (Sham; left muscle) and were sacrificed (n = 5 per group) on the 1st, 7th, and 15th day post-injection (dpi). Histological and immunohistochemical analyses were used to calculate myotube percentage and fibrosis accretion, and quantify the number of neutrophils and M1 and M2 macrophage subtypes. The SED group showed an increased number of both neutrophils and M1 macrophages (7th and 15th dpi) compared to the EX group (p < 0.01). The EX group showed an increased number of M2 macrophages on the 1st dpi. On the 7th dpi, the SED group showed a lower myotube percentage compared to the EX group (p < 0.01) and on the 15th dpi showed only
54% of normal undamaged fibres compared to 90% from the EX group (p < 0.01). The SED group showed increased fibrosis on both the 7th and 15th dpi. Our results show that sedentary behaviour affects the inflammatory response, enhancing and prolonging the Th1 phase, and delays and impairs the SMR process.DB19-D819-F720 | Carlos Eduardo da Silva TeixeiraN/
CT Radiomics in Colorectal Cancer: Detection of KRAS Mutation Using Texture Analysis and Machine Learning
In this work, by using descriptive techniques, the characteristics of the texture of the CT (computed tomography) image of patients with colorectal cancer were extracted and, subsequently, classified in KRAS+ or KRAS-. This was accomplished by using different classifiers, such as Support Vector Machine (SVM), Grading Boosting Machine (GBM), Neural Networks (NNET), and Random Forest (RF). Texture analysis can provide a quantitative assessment of tumour heterogeneity by analysing both the distribution and relationship between the pixels in the image. The objective of this research is to demonstrate that CT-based Radiomics can predict the presence of mutation in the KRAS gene in colorectal cancer. This is a retrospective study, with 47 patients from the University Hospital, with a confirmatory pathological analysis of KRAS mutation. The highest accuracy and kappa achieved were 83% and 64.7%, respectively, with a sensitivity of 88.9% and a specificity of 75.0%, achieved by the NNET classifier using the texture feature vectors combining wavelet transform and Haralick coefficients. The fact of being able to identify the genetic expression of a tumour without having to perform either a biopsy or a genetic test is a great advantage, because it prevents invasive procedures that involve complications and may present biases in the sample. As well, it leads towards a more personalized and effective treatmentThis work has received financial support from the Xunta de Galicia (Centro singular de investigación de Galicia, accreditation 2020–2023) and the European Union (European Regional Development Fund—ERDF), Project MTM2016-76969-PS
How you move reveals who you are: understanding human behavior by analyzing trajectory data
The widespread use of mobile devices is producing a huge amount of trajectory data, making the discovery of movement patterns possible, which are crucial for understanding human behavior. Significant advances have been made with regard to knowledge discovery, but the process now needs to be extended bearing in mind the emerging field of behavior informatics. This paper describes the formalization of a semantic-enriched KDD process for supporting meaningful pattern interpretations of human behavior. Our approach is based on the integration of inductive reasoning (movement pattern discovery) and deductive reasoning (human behavior inference). We describe the implemented Athena system, which supports such a process, along with the experimental results on two different application domains related to traffic and recreation management
The role of hybrid chitosan membranes on scarring process following lumbar surgery: post-laminectomy experimental model
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