bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Learning of Odor–Value Association in the Olfactory Striatum
Authors: Millman Daniel J. , Murthy Venkatesh N.
Published: April 2020

Rodents can successfully learn multiple novel stimulus–response associations after only a few repetitions when the contingencies predict reward. The circuits modified during such reinforcement learning to support decision-making are not known, but the olfactory tubercle (OT) and posterior piriform cortex (pPC) are candidates for decoding reward category from olfactory sensory input and relaying this information to cognitive and motor areas. Through single-cell recordings in behaving male and female C57BL/6 mice, we show here that an explicit representation for reward category emerges in the OT within minutes of learning a novel odor–reward association, whereas the pPC lacks an explicit representation even after weeks of overtraining. The explicit reward category representation in OT is visible in the first sniff (50–100 ms) of an odor on each trial, and precedes the motor action. Together, these results suggest that the coding of stimulus information required for reward prediction does not occur within olfactory cortex, but rather in circuits involving the olfactory striatum.

SIGNIFICANCE STATEMENTRodents are olfactory specialists and can use odors to learn contingencies quickly and well. We have found that mice can readily learn to place multiple odors into rewarded and unrewarded categories. Once they have learned the rule, they can do such categorization in a matter of minutes (<10 trials). We found that neural activity in olfactory cortex largely reflects sensory coding, with very little explicit information about categories. By contrast, neural activity in a brain region in the ventral striatum is rapidly modified in a matter of minutes to reflect reward category. Our experiments set up a paradigm for studying rapid sensorimotor reinforcement in a circuit that is right at the interface of sensory input and reward areas.
Selective Disruption of Inhibitory Synapses Leading to Neuronal Hyperexcitability at an Early Stage of Tau Pathogenesis in a Mouse Model
Authors: Shimojo Masafumi , Takuwa Hiroyuki , Takado Yuhei , Tokunaga Masaki , Tsukamoto Satoshi , Minatohara Keiichiro , Ono Maiko , Seki Chie , Maeda Jun , Urushihata Takuya , Minamihisamatsu Takeharu , Aoki Ichio , Kawamura Kazunori , Zhang Ming-Rong , Suhara Tetsuya , Sahara Naruhiko , Higuchi Makoto
Published: April 2020

Synaptic dysfunction provoking dysregulated cortical neural circuits is currently hypothesized as a key pathophysiological process underlying clinical manifestations in Alzheimer's disease and related neurodegenerative tauopathies. Here, we conducted PET along with postmortem assays to investigate time course changes of excitatory and inhibitory synaptic constituents in an rTg4510 mouse model of tauopathy, which develops tau pathologies leading to noticeable brain atrophy at 5-6 months of age. Both male and female mice were analyzed in this study. We observed that radiosignals derived from [11C]flumazenil, a tracer for benzodiazepine receptor, in rTg4510 mice were significantly lower than the levels in nontransgenic littermates at 2-3 months of age. In contrast, retentions of (E)-[11C]ABP688, a tracer for mGluR5, were unaltered relative to controls at 2 months of age but then gradually declined with aging in parallel with progressive brain atrophy. Biochemical and immunohistochemical assessment of postmortem brain tissues demonstrated that inhibitory, but not excitatory, synaptic constituents selectively diminished without overt loss of somas of GABAergic interneurons in the neocortex and hippocampus of rTg4510 mice at 2 months of age, which was concurrent with enhanced immunoreactivity of cFos, a well-characterized immediate early gene, suggesting that impaired inhibitory neurotransmission may cause hyperexcitability of cortical circuits. Our findings indicate that tau-induced disruption of the inhibitory synapse may be a critical trigger of progressive neurodegeneration, resulting in massive neuronal loss, and PET assessments of inhibitory versus excitatory synapses potentially offerin vivoindices for hyperexcitability and excitotoxicity early in the etiologic pathway of neurodegenerative tauopathies.

SIGNIFICANCE STATEMENTIn this study, we examined the in vivo status of excitatory and inhibitory synapses in the brain of the rTg4510 tauopathy mouse model by PET imaging with (E)-[11C]ABP688 and [11C]flumazenil, respectively. We identified inhibitory synapse as being significantly dysregulated before brain atrophy at 2 months of age, while excitatory synapse stayed relatively intact at this stage. In line with this observation, postmortem assessment of brain tissues demonstrated selective attenuation of inhibitory synaptic constituents accompanied by the upregulation of cFos before the formation of tau pathology in the forebrain at young ages. Our findings indicate that selective degeneration of inhibitory synapse with hyperexcitability in the cortical circuit constitutes the critical early pathophysiology of tauopathy.
A College–High School Collaboration to Support Authentic Microbiology Research
Authors: Petersen Joan , Chan Patrick
Published: April 2020

A partnership between a community college biology professor and a local high school teacher was established to engage high school students in authentic microbiology research. High school students isolated actinomycetes from soil samples and tested them for their ability to produce antimicrobial chemicals. They also designed and carried out their own experiments with these isolates. Laboratory reports, written assignments, and quizzes were used to assess the scientific learning of the subject covered by the research project. The students' attitudes about science and scientific research were assessed using a standardized survey and written reflection questions. In completing this project, the students applied their knowledge of the scientific method and experimental design to address authentic research questions. They also learned several hands-on laboratory skills, including serial dilution, aseptic technique, isolation of pure cultures, Gram staining, microscopy, and antimicrobial testing. Student feedback was overwhelmingly positive – many expressed an increased interest in pursuing a career in science, and most felt that the project helped them gain confidence in their ability to do science. This project illustrates the importance of establishing partnerships between secondary schools and academic institutions to successfully introduce research to younger students.
Insect World: Game-Based Learning as a Strategy for Teaching Entomology
Authors: Cosme Lírio , Turchen Leonardo M. , Guedes Raul Narciso C.
Published: April 2020

The use of game activities is spreading in diverse contexts, including stimulating teamwork and creativity, selecting job candidates, and as a teaching aid. Games are recognized as promoting interaction and engagement among children through an abstract challenge, which often results in emotional reactions. We investigated whether a game-based activity is useful as a tool for teaching entomology, as assessed on the basis of the learning achieved and the feedback provided by students. Student feedback was positive regarding card content, the rules manual, game-play design, and game use (the functional perspective). Likewise, the students also considered the game a fun activity, fast and competitive, and even challenging (the personal perspective). Some difficulties were indicated, such as the amount of initial information required to play. Nonetheless, the game increased student learning, demonstrating its usefulness as a didactic activity in the classroom. In addition to encouraging creativity and healthy competition among students, the game represents an integrative and dynamic teaching mode that is different from traditional classroom methods.
Taking Temperature with Leaves: A Semester-Long Structured-Inquiry Research Investigation for Undergraduate Plant Biology
Authors: Copenhaver-Parry Paige E.
Published: April 2020

Inquiry- and course-based research pedagogies have demonstrated effectiveness for preparing undergraduate biology students with authentic scientific skills and competencies, yet many students lack the experience to engage successfully in open-ended research activities without sufficient scaffolding and structure. Further, curricula for student-centered laboratory activities are lacking for several biological disciplines, including plant biology and botany. In this article, I describe a semester-long structured-inquiry research curriculum developed for a plant biology course taught to second-year biology students that integrates key elements of inquiry and discovery while providing a structured approach to gaining research skills. In the research project, students collect leaves from woody dicot plants across a range of environments that are characterized by different mean annual temperatures, and investigate the relationship between various leaf characteristics and temperature. Curricular materials are provided to teach skills in scientific paper reading, field data collection, data processing including microscopy and image analysis, quantitative data analysis in R, biological inference, and scientific writing. This comprehensive, ready-to-implement curriculum is suitable for plant biology, botany, and plant ecology courses and is particularly valuable for students with no prior research experience.
Under the Scope: Microscopy Techniques to Visualize Plant Anatomy & Measure Structures
Authors: Koehler Alyssa M. , Larkin Maximo T. , Shew H. David
Published: April 2020

Microscopy and stained specimens engage students visually as they learn about plant anatomy, a topic covered in many biology and introductory science courses. In this activity, students section plant material and prepare specimens to view under a brightfield microscope. Using a camera or cell phone, images of microscope slide contents allow students to label plant parts and engage in discussions with peers. The addition of scale bars to their images will allow a better understanding of the relationships of the various structures observed in the functioning of plants.
Transforming the Culture of Chinese Prosecutors Through Guiding Cases
Authors: Hawes Colin
Published: April 2020

Public prosecutors are a key element within the legal complex, and crucial to the effective implementation of legal reforms. China’s procurators (public prosecutors) have previously colluded with local governments, police, and courts to “strike hard” against crime while overlooking systemic beating and torture of detained suspects to obtain confessions, shoddy investigative practices, and frequent miscarriages of justice.

However, fifteen sets of Guiding Cases issued by the Supreme People’s Procuratorate since 2010 promote an unprecedented change in Chinese procurator culture away from “striking hard” to substantive protection of criminal suspects’ rights and exclusion of tainted evidence. They reinforce criminal procedure reforms since 2010 by demonstrating how procurators should protect innocent people against wrongful convictions and police brutality. They also stress the broader duty of China’s procurators to uphold the public interest against corrupt businesses and officials, especially in food safety, land-taking, and environmental protection cases.

With other key actors in China’s “legal complex”—rights lawyers and civil society groups—still suppressed by the government, this effort to transform procurator culture is an essential, though still incomplete, step on China’s tortuous path toward a fair and just legal system.
Japanese Farmers, Mexican Workers, and the Making of Transpacific Borderlands
Authors: Tokunaga Yu
Published: April 2020

Launched by Mexican farmworkers against Japanese farmers in Los Angeles, the 1933 El Monte Berry Strike became one of California’s largest labor conflicts. The strike evolved from a local conflict into an international problem in which anti-Japanese sentiment travelled across the U.S.-Mexico border, merged with Mexican nationalism, and forced Japanese residents in Mexico to issue an unexpected pro-strike statement against their co-ethnics in Los Angeles. Using Japanese diplomatic documents and local ethnic newspapers, this article details the process by which Mexican nationalism trumped ethnic solidarity among Japanese immigrants in the transpacific borderlands, where local and international concerns of Japan, Mexico, and the United States intersected. The exacerbating situation in Mexico, rather than in California, played a decisive role in the settlement of the strike.
The Scaffold Proteins Paxillin B and α-Actinin Regulate Septation in Aspergillus nidulans via Control of Actin Ring Contraction
Authors: Zhou Xiaogang , Zheng Likun , Guan Luyu , Ye Jing , Virag Aleksandra , Harris Steven D , Lu Ling
Published: April 2020

Cytokinesis, as the final step of cell division, plays an important role in fungal growth and proliferation. In the filamentous fungus Aspergillus nidulans, defective cytokinesis is able to induce abnormal multinuclear or nonnucleated cells and then result in reduced hyphal growth and abolished sporulation. Previous studies have reported that a conserved contractile actin ring (CAR) protein complex and the septation initiation network (SIN) signaling kinase cascade are required for cytokinesis and septation; however, little is known about the role(s) of scaffold proteins involved in these two important cellular processes. In this study, we show that a septum-localized scaffold protein paxillin B (PaxB) is essential for cytokinesis/septation in A. nidulans. The septation defects observed in a paxB deletion strain resemble those caused by the absence of another identified scaffold protein, α-actinin (AcnA). Deletion of α-actinin (AcnA) leads to undetectable PaxB at the septation site, whereas deletion of paxB does not affect the localization of α-actinin at septa. However, deletion of either α-actinin (acnA) or paxB causes the actin ring to disappear at septation sites during cytokinesis. Notably, overexpression of α-actinin acnA partially rescues the septum defects of the paxB mutant but not vice versa, suggesting AcnA may play a dominant role over that of PaxB for cytokinesis and septation. In addition, PaxB and α-actinin affect the septal dynamic localization of MobA, a conserved component of the SIN pathway, suggesting they may affect the SIN protein complex function at septa. Protein pull-down assays combined with liquid chromatography–mass spectrometry identification indicate that α-actinin AcnA and PaxB likely do not directly interact, but presumably belong to an actin cytoskeleton protein network that is required for the assembly and contraction of the CAR. Taken together, findings in this study provide novel insights into the roles of conserved scaffold proteins during fungal septation in A. nidulans.
Patterns and trends of pediatric and young adult computed tomography use in Brazil: 2008-2014
Authors: Dovales Ana Cristina Murta , Chaves Tainá Olivieri , Bahia Paulo Roberto Valle , Schaefer Marcela Brisighelli , Failla Bruna Bonaventura , Suzuki Lisa , Valente Marcelo , Gomes Vinicius de Araújo , Da Rosa Luiz Antônio Ribeiro , Pearce Mark Stephen , Veiga Lene Holanda Sadler
Published: April 2020

ABSTRACT Computed tomography (CT) is an indispensable imaging technique, but radiation exposure from CT scans is of concern mainly due to the potential risk of developing cancer, mainly in children. Our group recently showed that CT use has greatly increased among outpatients using the Brazilian public health system (SUS) between 2001 and 2011. Further, CT examinations among patients younger than 20 years of age represented around 13.4% of all CT examinations in SUS between 2008 and 2011. In comparison, these examinations represented around 8% of the overall number of CT scans in a private hospital in Rio de Janeiro between 2005 and 2015, In this paper we extended the evaluation of pediatric and young adult CT use in Brazil to 25 private CT services in 8 Brazilian cities for the period 2008-2014. Data from SUS was updated to this period. Information about CT use in SUS was obtained from an online database. Data on the privately funded setting was retrieved from the Radiological Information Systems (RIS) of each CT service. Patients younger than 20 years of age underwent around 8.9% of the CT procedures in the private setting, while in SUS this proportion was around 12.7% in the same period. Pediatric and young adult CT greatly increased in both healthcare systems, but annual growth rates were less pronounced in the private than in the public healthcare system. One third of the patients in the private setting had more than one CT examination over the period investigated.
Image quality evaluation of a small animal PET scanner
Authors: Ferreira Andréa Vidal , Gontijo Rodrigo Modesto Gadelha , Souza Guilherme Cavalcante de Albuquerque , Mendes Bruno Melo , Silva Juliana Batista da , Mamede Marcelo
Published: April 2020

Performance testing of small animal PET scanners is very important to ensure the high performance required for this particular type of PET scanner. In this sense, National Electrical Manufactures Association (NEMA) published its NU 4/2008 standards, a consistent and standardized methodology for measuring scanner performance parameters for small animal PET imaging. Imaging capabilities of the scanner LabPET SOLO 4 were tested during two years according NEMA NU 4/2008 methodology. Results indicates that the equipment, despite a decade of use, presents performance appropriated and similar to performance of equipments reported in Literature.
5X5 Rod Bundle Flow Field Measurements Downstream a PWR Spacer Grid
Authors: Castro Higor Fabiano Pereira de , Silva Vitor Vasconcelos Araújo , Santos Andre Augusto Campagnole dos , Veloso Maria Auxiliadora Fortini
Published: April 2020

The spacer grids are structures present in nuclear fuel assembly of Pressurized Water Reactors (PWR). They play an important structural role and also assist in heat removal through the assembly by promoting increased turbulence of the flow. Understanding the flow dynamics downstream the spacer grid is paramount for fuel element design and analysis. This paper presents water flow velocity profiles measurements downstream a spacer grid in a 5x5 rod bundle test rig with the objective of highlighting important fluid dynamic behavior near the grid and supplying data for CFD simulation validation. These velocity profiles were obtained at two different heights downstream the spacer grid using a LDV (Laser Doppler Velocimetry) through the top of test rig. The turbulence intensities and patterns of the swirl and cross flow were evaluated. The tests were conducted for Reynolds numbers ranging from 1.8x104 to 5.4x104. This experimental research was carried out in thermohydraulics laboratory of Nuclear Technology Development Center – CDTN. Results show great repeatability and low uncertainties (< 1.24 %). Details of the flow field show how the mixture and turbulence induced by the spacer grid quickly decays downstream the spacer grid. It is shown that the developed methodology can supply high resolution low uncertainty results that can be used for validation of CFD simulations.
Study of thorium and uranium isotopes activity concentration after percolation or agitation leaching, in mining lixiviation liquor samples
Authors: Reis Aluisio Souza , Monteiro Roberto Pellacani Guedes
Published: April 2020

This work refers to determination of thorium and uranium isotopes in the mining lixiviation liquor samples. The analytical procedure involves sample preparation steps for rare earth elements, thorium and uranium separation, besides alpha spectrometry analysis of the isolated radionuclides. An isotopic tracer is used to determine the overall chemical yield and to ensure traceability to a standard sample from NIST. The paper presents and discusses that the chemical yield of thorium and uranium depends on the leaching method used, that is, column leaching or agitated leaching. We improved the method looking for reproducibility and isotopes isolation as required by alpha spectrometry and the method showing effective in analysis of mining liquor
Aplicação do material gesso e mistura gesso e barita como blindagem para baixas energias na área de radiodiagnóstico, nível mamografia.
Authors: Lins Jorge Alexandre Gomes , Lima Fernando Roberto de Andrade , Dos Santos Marcus Aurélio Pereira , De Oliveira Alex Cristóvão Holanda , Da Silva Victor Hugo Farias Ferreira
Published: April 2020

A radiologia diagnóstica está em evolução contínua, em resposta ao desenvolvimento tecnológico, permitindo diagnósticos com qualidade cada vez melhor [1]. Contudo, se faz necessário o estudo de materiais aplicados como barreiras de proteção, objetivando reduzir a intensidade das radiações ionizantes, além de aperfeiçoar o dimensionamento e aumentar o conhecimento das propriedades de atenuação para outros materiais.O material gesso foi escolhido pois o presente estudo científico foi feito no estado de Pernambuco, onde está situado o Pólo Gesseiro do Araripe, no qual se tem a maior produção de gesso do Brasil e onde esse material pode ser encontrado com um grande percentual de pureza. Além do gesso puro, foi utilizada uma mistura de gesso com barita com o objetivo de se alcançar uma maior densidade do material irradiado, assim tendo-se uma melhor atenuação.As medidas experimentais foram realizadas em laboratório de metrologia ao qual tinham qualidades de referência WMV implantadas – qualidades de raios X que caracteriza feixes de mamografia, de acordo com os padrões do laboratório Alemão Physikalisch-Technische Bundesanstalt (PTB).
Asking for Identification and Retail Tobacco Sales to Minors
Authors: Levinson Arnold H. , Lee Joseph G.L. , Jason Leonard A. , DiFranza Joseph R.
Published: April 2020

BACKGROUND AND OBJECTIVES:

A previous single-county study found that retail stores usually asked young-looking tobacco customers to show proof-of-age identification, but a large proportion of illegal tobacco sales to minors occurred after the customers had shown identification proving they were too young to purchase tobacco. We sought to investigate these findings on a larger scale.

METHODS:

We obtained state reports for federal fiscal years 2017 and 2018 from a federal agency that tracks tobacco sales to supervised minors conducting compliance checks in retail stores. We used descriptive and multivariable logistic regression methods to determine (1) how often stores in 17 states requested identifications, (2) what proportion of violations occurred after identification requests, and (3) if violation rates differed when minors were required versus forbidden to carry identification.

RESULTS:

Stores asked minors for identification in 79.6% (95% confidence interval: 79.3%–80.8%) of compliance checks (N = 17 276). Violations after identification requests constituted 22.8% (95% confidence interval: 20.0%–25.6%; interstate range, 1.7%–66.2%) of all violations and were nearly 3 times as likely when minors were required to carry identification in compliance checks. Violations were 42% more likely when minors asked for a vaping product versus cigarettes.

CONCLUSIONS:

Stores that sell tobacco to underage customers are more likely to be detected and penalized when youth inspectors carry identification during undercover tobacco sales compliance checks. The new age-21 tobacco sales requirement presents an opportunity to require identifications be carried and address other long-standing weaknesses in compliance-check protocols to help combat the current adolescent vaping epidemic.
Enriquecimiento de la matriz biológica cidra Sechium edule (Jacq.) Sw. con Lactobacillus casei y saborizada con maracuyá Passiflora edulis L
Authors: Obando Mejia Francisco Fernei , Mejia Doria Clara María , Duque Cifuentes Alba Lucia
Published: April 2020

Los probióticos son bacterias ácido-lácticas que mejoran el equilibrio microbiano. El objetivo de esta investigación fue enriquecer la matriz cidra con Lactobacillus casei y saborizarla con maracuyá. Se determinó la porosidad y se realizó impregnación a vacío a geometrías de cidra con formulaciones de maracuyá; las muestras de cidra se caracterizaron fisicoquímicamente. Se realizó el enriquecimiento con Lactobacillus casei con 109 UFC/mL y se evalúo la viabilidad de los microorganismos. Los resultados mostraron valores similares de porosidad en paralelepípedos y láminas (0,995±0,003 y 0,991±0,005, respectivamente); mientras que los ºBrix (9,9±0,12 y 10,2±0,12) y el pH (6,03±0,01 y 6,06±0,01) fueron mayores en láminas; la acidez titulable (0,301±0,012 y 0,258±0,012) fue mayor en paralelepípedos, presentaron mayor viabilidad después de 20 días de almacenamiento con valores superiores a 106 UFC/g y mayor aceptación sensorial. La formulación 75:25 pulpa:agua y la geometría en paralelepípedos presentaron las condiciones más adecuadas para la incorporación del probiótico.
Determination of citric and oxalic acid in fungi fermentation broth through HPLC-DAD and solid-phase extraction
Authors: Trujillo Vargas Laura Marcela , Vélez Salazar Yesid Hernan , Ramírez Carmona Margarita Enid
Published: April 2020

This work describes a method for the simultaneous determination of organic acids in fungi fermentation broths. The sample preparation technique and the chromatographic conditions were optimized to enable the monitoring of the fermentation process. The determination of the citric and oxalic acid was done with a high resolution liquid chromatograph adapted to a detector with diode arrangement, an IC-Pak Ion-Exclusion 7μm (7.8 x 300 mm) column and a mobile phase of 0.001N H2SO4 with isocratic elusion. The validation parameters show efficiency, adequate linearity, and standard deviation values (%RSD) from 0.018% and 4.650%. the quantification limits (LDC) were 50.76 mg/L for citric acid and 20.18 mg/L for oxalic acid and the detection limits (LDD) were 0.6 mg/L for both acids. The method was applied in the analysis of organic acids in fermentation broths of Aspergillus niger.
Antipersonnel landmines in the Colombian internal conflict: implications for technology development
Authors: Vega Uribe Jesus Antonio , Sahli Hichem , Gauthier Sellier Alain
Published: April 2020

The effort of universities, companies, and the state in Colombia to face home-made AP landmines has generated useful solutions and studies for many projects developed in the last decade, including demining processes in Colombia. Antipersonnel mines have changed in the last 15 years, due to the intermittent nature of our internal conflict. For example, as Descontamina Colombia mentions on its website, non-state armed groups cut the detonator containing the primary explosive to decrease the metal in the mine. This paper shows the aspects of the conflict that have affected humanitarian demining in Colombia, which help in the design and construction of technological devices. This article does not attempt to describe each of the typical technologies in humanitarian demining processes, but rather to show the characteristics considered in the design of two detection devices aimed at detecting home-made AP landmines.
Evaluation of a biodegradable color concentrate in bags for coffee seedlings
Authors: Alban Bolaños Pedro , Parra Campos Amanda , Villada Castillo Hector Samuel , Portela Guarín Hugo , Arboleda Muñoz German Antonio , Palacios Lily Marcela
Published: April 2020

The aim of this study was to evaluate different formulations of a biodegradable black concentrate obtained from cassava starch and carbon black, on the mechanical properties, color, and water absorption of a film destined to the production of biodegradable bags for coffee seedlings. The modulus of elasticity, tensile strength and elongation properties is found to show significant variation due to the pigment, plasticizer, and lubricant concentration, both longitudinally and transversely of the film, the treatment being 40% pigment with the absence of plasticizer and lubricant for the pigment, which presented greater integrity in the mechanical properties evaluated in both directions. It is also noticeable that the different masterbatch formulations had an influence on the changes in the color parameters and weight gain of the film by the influence of water absorption.
Updating the finite element model of a Colombian Bridge with Ansys
Authors: Sequera Gutierrez Diego , Solano Rodríguez Luis Felipe , Muñoz Díaz Edgar Eduardo , Alvarado Vargas Yezid Alexander , Villalba Morales Jesús Daniel , Gasch Molina Isabel
Published: April 2020

Updating structural model is a knowledge field that have been studied in the last decades to guarantee the reliability on the model defined to represent the behavior of a structure, but generally implies the use of different software to carry out the different parts of the process. This paper presents the updating of the finite element model of a curve-alignment reinforced concrete bridge located near to the city of Ubaté in Colombia by using the optimization tool available in software Ansys and ambient vibration measurements. The use of such type of information avoids to carry out forced-vibration test, which affect the normal operation of the bridge. The objective function corresponds to the minimization of the error between analytical and experimental natural frequencies of the bridge. The design variables correspond to the material properties of the concrete and the elastomeric bearings. Results show that the error was decreased to less than 2%. The sensibility analysis allowed to determine which variables are more sensible to affect the natural frequencies in the structure.
Proposal for the risk analysis for silica exposure based on the respirable fraction dust
Authors: Toro Marín Jhon Edison , Longas-Restrepo Alexander
Published: April 2020

Crystalline silica is a natural chemical compound present in rocks, sand and soil. In industry, it is found in chemical products: cement, bricks, concrete... To measure the amount of silica a worker breathes, a dust sample must be taken from the respirable fraction. Due to the cost of chemical analysis of this fraction against silica, whose proportion is approximately 1:25, it is important to establish a methodology that allows an approximation of the risk calculation related to silica exposure, in order to reduce it. According to this, 63 data (2016-2019) were analysed, corresponding to measurements of the aforementioned dust with emphasis on silica belonging to industrial processes. The data were then analysed, and a statistically acceptable relationship was found for different industrial processes, resulting in a mathematical equation to determine the amount of silica, as a function of the amount of respirable fraction, with a statistical acceptance level.
Entropy generation analysis for the design of a flat plate solar collector with fins
Authors: Muñoz Milton , Roa Manuel , Correa Rodrigo
Published: April 2020

This article describes the optimal design of a flat-plate solar collector with fins, based on the minimum entropy generation criterion. The design parameters were optimized, considering entropy generation due to heat transfer and airflow. The latter has not been considered in previous works. The flat plate in the collector is assimilated to a finned heat sink. The dimensionless entropy generation variation is analyzed to increase values of the number of fins, as well as for different plate thicknesses and heights. We also considered variations in airflow velocity. Our data shows that airflow velocity greatly influences entropy generation. Values other than the optimum found, caused a considerable growth of total entropy. For a collector area of 4 m2, and an outlet temperature of 50°C, the optimum parameters that minimize the entropy generation rate were: 9 fins on each side of the collector plate, a height of 5 x10-2 m, a thickness of 25x10-3m, and an air velocity variable between 0.015 and 0.046 m/s. This development is relevant to the design of flat plate solar collectors, for grain drying applications.
Seismic performance analysis and assessment of a precast bridge computational model
Authors: Benjumea José , Saiidi Mehdi , Itani Ahmad
Published: April 2020

A large-scale, two-span bridge model constructed by assembling precast elements was tested under a series of bi-axial ground motionssimulated on a shake table at the Earthquake Engineering Laboratory at the University of Nevada, Reno. The response of the bridge wasestimated before the tests using a three-dimensional computational model developed in OpenSees software. After the tests, key measuredseismic responses were compared to those predicted by the computational model to assess the modeling assumptions. Relatively largeerrors for the displacements, base shears, and hysteretic response of the bridge were observed. The influence of the earthquake loading,materials, connectivity of the precast elements, and boundary conditions in the computational model on the errors are discussed in thispaper. Future modeling directions are proposed to reduce these errors.
Composite materials reinforced with ceramic waste and matrix of unsaturated polyester for applications in the automotive industry
Authors: Velasco Parra Jorge Antonio , Ramón Valencia Bladimir A. , Mora Espinosa William Javier
Published: April 2020

In the present investigation an alternative of recycling was evaluated for the residues derived from defective pieces of the ceramic industry, harnessing them as reinforcement in composite materials for the manufacture of parts used in the automotive sector. Sintered clay microparticles to 10% p/p were mixed in an unsaturated polyester resin matrix, through the cast molding technique. Bending tests were performed that showed an elastic-linear behavior, typical of a fragile material. The structure was analyzed through scanning electron microscopy, checking the fragile failure mechanism and a good dispersion of the microparticles. A simulation was carried out with the finite element method, for the design of a motorcycle brake lever, with results that demonstrate a better distribution of stresses and reduction in mass with respect to the original part. Finally, a prototype brake lever was manufactured using computationally validated geometry.
Colombian clays binary mixtures: physical changes due to thermal treatments
Authors: Betancourt Parra Santiago , Domínguez Ortíz Manuel Alejandro , Martinez Tejada Marcela
Published: April 2020

Usually, smectite clays, which are used for catalytic purposes, are subjected to chemical and thermochemical treatments to enhance their surface features. This research aims to analyze textural and structural features of the physical mixtures of two Colombian smectite clays at room temperature and after the treatment at 600°C, 800°C, and 1000°C. The physical mixtures of two Colombian clays were characterized by X-ray techniques, thermal analysis, and BET surface area to evaluate physical changes resulting from the three thermal treatments. The results showed the appearance of microstructural changes in basal spacing and other crystals minerals because of the loss of carbonates and alkaline oxides in the clays. Additionally, a dramatic reduction in surface area features was evidenced by the temperature increase. Simultaneously, an increase in the pore size was also observed because of the increase of the temperature treatment. The results reveal that the physical mixture is not an appropriate solution to enhance the textural properties of the Colombian clays for sorption or catalytic purposes.
Immobilization of DNA probes on a high frequency piezoelectric biosensor
Authors: Ortiz Monsalve Camilo , Guerra González Jorge Mario , Jaramillo Grajales Marisol
Published: April 2020

In recent years, researchers have taken to biosensors as effective tools for detection due to their portability, low-cost, fast response, and practicality. Piezoelectricity gave way to quartz crystal microbalances (QCM), of which high-frequency QCMs (HFF-QCM 100MHz) are still being researched. In this paper, we use DNA immobilization on a HFF-QCM via self-assembled monolayers (SAM) technique. Immobilization was initially verified with ATR-FTIR. Then, DNA was immobilized in real time on the HFF-QCM crystals. A variation in the phase of the signal suggests fixation of DNA to the surface, in accordance with ATR-FTIR results. A density of 629 ng/cm2 was computed. Also, a positive correlation between immobilized DNA and DNA concentration, and the appearance of a saturation point between 1 and 5 μM were shown after analysis of different DNA concentrations.
Optimized registration based on an ant colony for markerless augmented reality systems
Authors: Jaramillo-Rojas Gloria Elena , Branch Bedoya John William
Published: April 2020

Accurate registration in augmented reality systems is essential to guarantee the visual consistency of the augmented environment. Although error in the virtual-real alignment is almost unavoidable, different approaches have been proposed to quantify and reduce such errors. However, many of the existing solutions require a lot of a priori information, or they only focus on camera calibration to guarantee good results in the registration. This article presents a heuristic method that aims to reduce registration errors in markerless augmented reality systems. The proposed solution sees error reduction as a mono-objective optimization problem, which is addressed by means of the Ant Colony Optimization (ACO) algorithm. Experimental results reveal the validity of the proposed method, reaching an average error of 1.49 pixels for long video sequences.
Uma breve síntese do perfil de alunos bolsistas em uma universidade comunitária do RS: contribuições para a trajetória acadêmica na graduação
Authors: Schuh Malu Santarem , Machado Maria Elisabete , Casartelli Alam De Oliveira
Published: April 2020

O presente artigo objetiva apresentar uma breve síntese do perfil de alunos bolsistas matriculados nos cursos de graduação de uma universidade comunitária. Entende-se que ao conhecer tal realidade será possível contribuir para com suas trajetórias de formação. Nessa perspectiva, no decorrer do estudo, aborda-se a trajetória dos alunos bolsistas que acessam o campus universitário por meio de políticas públicas, com vistas a compreender suas estratégias para permanecer e concluir sua formação, como processo relevante para o progresso profissional. Para a construção deste estudo, recorreu-se ao aporte teórico de estudiosos como Dubar (1996; 2005), Josso (2007), Morosini (2006), Ristoff (2014) e Zabalza (2004), além do amparo legal que subsidia a existência de programas que permitem o acesso desse público à graduação. Para tanto, promoveu-se um estudo de caso (YIN, 2010) ambientado na Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), por meio de uma pesquisa quantitativa (MALHOTRA, 2006) cujo instrumento utilizado foi um questionário direcionado a uma amostra representativa de alunos, a fim de quantificar as informações. A análise e a interpretação dos dados ocorreram por meio de estatísticas descritivas, de acordo com o que preconiza Malhotra (2006). Como principais resultados, elencam-se a caracterização do perfil de alunos bolsistas na universidade, os desafios e as possibilidades no decorrer da trajetória acadêmica, envolvendo majoritariamente estudantes/trabalhadores.
Dificuldades de comunicação em um curso de licenciatura para os anos iniciais na modalidade de Ensino a Distância
Authors: Da Costa Alberto Luiz Pereira
Published: April 2020

O objetivo da investigação foi entender como ocorre a comunicação no processo de ensino e aprendizagem entre os docentes universitários responsáveis pelo módulo de geometria e tutores de um Curso Licenciatura para os Anos Iniciais na modalidade de Ensino a Distância, oferecido por uma Universidade Pública do Paraná. Na metodologia nos pautamos na Análise do Discurso nas interações ocorridas via plataforma. Os resultados obtidos ofereceram indícios para entender os problemas relacionados ao EAD. Com nossa pesquisa obtivemos um parâmetro do procedimento desenvolvido na ação educativa, além de analisarmos se essa interação contribui e de que modo para o trabalho a ser desenvolvido por esses tutores com os alunos do curso (os cursistas) em relação aos conteúdos desse conhecimento escolar.
O impacto da participação dos pais e encarregados de educação na gestão escolar: um estudo realizado na Escola do I Ciclo Elimabe I em Malanje
Authors: Cabamba João Isarael
Published: April 2020

A família é o centro de todo o processo de ensino e aprendizagem, pelo facto de ser a célula básica da sociedade e o local onde o educando passa maior tempo durante todo o acto da sua formação académica e social. A família, deve ser chamada para participar de forma reciproca na construção de um novo ser para o mundo, pois que a sociedade faz-se por consensos, esta participação provocará impacto na gestão do processo de ensino e aprendizagem. O educando, é aquele que terá a missão fundamental de assumir diferentes papéis para o desenvolvimento sustentável e integral da sociedade por todas as suas vertentes. A escola, deve promover uma gestão participativa, fazendo com que a família participe na gestão do processo educatico do aluno, garantido deste modo a qualidade do ensino. Este artigo, tem como objectivo geral abordar aspectos ligados ao grau de participação da família e o papel na gestão escolar como no rendimento das aprendizagens dos educandos. Seleccionamos as técnicas de entrevista e questionário, a metodologia é qualitativa com a amostra de 48 sujeitos, entre eles: director, professores, alunos pais e encarregados de educação, extraído num total da população de 211 elementos.
A escrita acadêmica na formação inicial de professores: diários de aprendizagem na constituição de si
Authors: Martins Adriana Claudia , Galvão dos Santos Eliane Aparecida
Published: April 2020

Nesta escrita apresentamos as experiências vivenciadas com a formação inicial de professores, tendo como objetivo discutir sobre o papel do diário de aprendizagem como um instrumento de interlocução na sala de aula universitária, entre professor formador e os acadêmicos, durante a formação inicial de professores.  Propomos a escrita de si como possibilidade de reflexão durante o processo formativo, considerando os movimentos de autorregulação de ser professor em formação a partir dos desafios do processo formativo. A natureza deste trabalho é de cunho qualitativo, ancorado na pesquisa bibliográfica em que a revisão da literatura teve como base os autores: Zabalza (2004), Freire (1996) e Bakhtin (2010a, 2010b). Assim, o texto se inscreve como teórico-analítico a partir de fragmentos de diários dos acadêmicos de cursos de licenciaturas. Para tanto, realizamos a análise dos diários de aprendizagem de nove estudantes do curso de Pedagogia e de Letras de duas universidades do interior do estado do Rio grande do Sul. A partir do estudo foi possível compreender que os acadêmicos vão se constituindo e dialogando ao escreverem os diários, colocando-se como aprendizes críticos no espaço da graduação, corroborando nos processos de elaboração de novos conhecimentos e aprendizagem de ser professor.
Múltiplos olhares de estudantes de um curso de licenciatura sobre a docência orientada: reflexões necessárias.
Authors: Da Silva Mariane Carloto , Pereira Sandra Regina Costa , Pavão Silvia Maria de Oliveira
Published: April 2020

O artigo apresenta os resultados de uma pesquisa sobre Docência Orientada desenvolvida em uma Universidade Federal de ensino localizada no Estado do Rio Grande do Sul. O objetivo geral proposto foi investigar as percepções dos estudantes de um curso de licenciatura em relação à Docência Orientada. Optou-se por um enfoque qualitativo de caráter exploratório-descritivo. A análise dos dados se deu por meio da técnica de Análise de Conteúdo (BARDIN, 2011), sendo apresentados em duas categorias: 1) Docência Orientada e as estratégias de ensino e 2) Dimensões da Docência sob a perspectiva dos estudantes. Concluiu-se que a Docência Orientada contribuiu para a apropriação dos conhecimentos ensinados durante a disciplina, principalmente pela presença de três docentes na sala, e que ainda é necessário fazer ajustes em relação à forma de apresentação da Docência Orientada proposta aos estudantes da Graduação, sendo importante a ampliação do exercício desta diante do potencial formativo para todos os envolvidos.
“Queremos ser sujeitos do sistema educacional”: as implicações do Trabalho Pedagógico na Permanência e Êxito de estudantes na Educação Profissional e Tecnológica
Authors: Silveira Rozieli Bovolini , Maraschin Mariglei Severo
Published: April 2020

Esse artigo é resultado de uma pesquisa de mestrado sobre o tema da permanência e o êxito de estudantes na Educação Profissional e Tecnológica. A pesquisa teve como ênfase a análise da política denominada Programa Permanência Êxito (PPE). O objetivo foi compreender as possíveis relações entre o Trabalho Pedagógico e o sucesso ou fracasso escolar e para isso, partiu de uma concepção crítica da educação. Como produção de dados foram entrevistados(as) os(as) coordenadores(as) do PPE e dos Eixos Tecnológicos, de dois campi do IF Farroupilha, além da aplicação de um questionário para os estudantes dos Cursos Técnicos e observações sistematizadas nos Diários de Campo. A partir da produção dos dados foi possível compreender que as relações no Trabalho Pedagógico ocorreram de duas formas, quando o estudante sente-se acolhido pela instituição ou quando as relações no T.P. reafirmam a exclusão, selecionando os mais “aptos”.
Tangenciamentos entre a Filosofia da Diferença e o Ensino de Matemática para Todos
Authors: Lanuti José Eduardo De Oliveira Evangelista
Published: April 2020

Ao reverter o pensamento platônico, dedicado à busca pela semelhança ao afirmar a necessidade da instituição de modelos para serem seguidos, Deleuze, inspirado pelas obras de Bergson, apresenta o conceito de diferença. Ainda que o filósofo não tenha criado conceitos pensando especificamente na escola, ao considerar cada pessoa como um ser único, sua filosofia desestrutura todos os tipos de negação do direito à diferença, que são formas de excluir aqueles que, injustamente, são tidos como os diferentes. É pelo estudo dos motivos, infundados, que têm a pretensão de justificar a categorização e exclusão de alguns alunos, que poderemos propor um ensino, de fato, para todos. A Matemática ainda é concebida como uma disciplina à parte das demais, de alcance de apenas uma parcela dos alunos que, supostamente, são capazes de entendê-la. Nessa perspectiva, ainda tão presente nas escolas, muitos são excluídos. Neste texto apresento os encaminhamentos de uma pesquisa de Doutorado em andamento que tem como matéria-prima de investigação uma formação docente em serviço com professores do Ensino Fundamental. As aproximações entre a filosofia deleuzeana e o ensino de Matemática têm provocado mudanças de concepções e de ações dos professores participantes.