Centro Federal de Educação Tecnológica Celso Suckow da Fonseca (CEFET/RJ)

Recently, we have experienced a long period of weakening of democracy and institutional dismantling in Brazil, which lasted until 2022. Concomitantly, the coronavirus epidemy got large proportions in the world, particularly in our country. Even though we achieved the victory of former President Lula in October of 2022, we experienced explicit threats to democracy and persistent disregard for the pandemic by the president in office until then. Our recent history has made us more aware of the relevance of promoting political reflection on educational processes in general and in science education. In this regard, the theoretical conception of the social and articulatory practices given by the theory of discourse (Laclau, E., & Mouffe, C. Hegemonía y estrategia socialista: hacia una radicalización de la democracia. Siglo XXI, 1987) appeared adequate. It allowed us to identify contingent discursive formations, which have been articulated in Brazilian science education scholarship, due to the demands generated in the political scenario. We propose the following research questions: how are hegemonic discourses constructed in Brazilian science education scholarship? What hegemonic discourses and possible discursive inflections can be perceived due to political and health demands generated in this historical scenario? Our findings revealed hegemonic discourses that reduce political demands to the investigation of educational policies, which has been resulting in a process of depoliticization of Brazilian science education scholarship. When the whole world was under the impact of the pandemic, only two articles mentioned the tragedy we lived in Brazil, where a denialist government was behind the death of 700,000 people from COVID-19.

The knowledge of the residual stresses generated in the welding process is especially important in the performance and service life of the welded structures and components. In this context, the present work aims to study the residual stresses generated in welded joints of advanced high strength steel (22MnB5), with Fe-Zn alloy coating, called GA (galvannealed), utilizing the resistance welding process. Residual stresses were experimentally analyzed using X-ray diffraction, employing the sen²psi technique. Vickers microhardness analyses were conducted, and the obtained measurements were incorporated into mathematical formulations to estimate the dislocation density in the analyzed region, employing a model based on microhardness measurements. Microstructural characterizations were carried out using optical microscopy (OM) and scanning electron microscopy (SEM), correlating with the residual stress results. The dislocation density results were approximately ρt = 7.42 × 10¹⁵ m² for the weld metal and 7.05 × 10¹⁷ m² for the base metal. The residual stress indicated compressive values with mean measurements ranging from 250 to 450 MPa, accompanied by hardness values spanning from 200 to 600 HV. These results demonstrate that the proposed technique holds promise for dislocation density evaluation. Keywords: Residual stress; Dislocation density; 22MnB5 steel welded joint; Vickers microhardness; Electric resistance welding process

A time-dependent, flavour-tagged measurement of CP violation is performed with B0 → D+D− and ${B}_s^0$ → ${D}_s^{+}{D}_s^{-}$ decays, using data collected by the LHCb detector in proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 6 fb−1. In B0 → D+D− decays the CP-violation parameters are measured to be In ${B}_s^0$ → ${D}_s^{+}{D}_s^{-}$ decays the CP-violating parameter formulation in terms of ϕs and |λ| results in These results represent the most precise single measurement of the CP-violation parameters in their respective channels. For the first time in a single measurement, CP symmetry is observed to be violated in B0 → D+D− decays with a significance exceeding six standard deviations.

This study investigates the impact of CuO (p-type) incorporation into TiO2 (n-type) photoanodes, sensitized with three different natural dyes extracted from scarlet eggplant, pitomba, and black grape fruits using ethanol, for dye sensitized solar cells (DSSCs). The natural dyes visible light absorption properties were characterized through ultraviolet–visible (UV–Vis) spectroscopy, while Fourier-transform infrared (FTIR) spectroscopy identified their functional groups. The structural and morphological features of TiO2 and TiO2/CuO nanocomposites were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Additionally, atomic force microscopy (AFM) was employed to evaluate the surface topographies of the photoanodes and cathode. The incorporation of CuO into the TiO2 matrix formed an n–p junction within the TiO2/CuO photoanode, significantly enhancing photocurrent, photovoltage, fill factor, and overall conversion efficiency. DSSCs fabricated with the TiO2/CuO photoanode sensitized by scarlet eggplant, pitomba, and black grape fruits natural dyes achieved maximum conversion efficiencies of 2.77, 2.81, and 5.22%, compared to lower efficiencies of 0.51, 0.56, and 1.12% obtained using unmodified TiO2 photoanodes, respectively. The results demonstrate the synergistic effect of the hybrid photoanode and natural dye sensitization in improving DSSC performance, highlighting the potential of sustainable and efficient energy solutions.

This study addresses the location of emergency rescue vehicle bases in the western region of the city of Rio de Janeiro. The research aims to serve the greatest number of people within WHO parameters, which stipulates a maximum waiting time of 10 min. Various scenarios are explored, varying the number of rescue vehicles from 10 to 50 and the number of bases from 10 to 22. The study reveals that having an adequate number of rescue vehicles is crucial before determining the number and locations of the bases. Even in optimized scenarios with 5 or 8 bases, population coverage still falls short of the ideal, especially for 10‐min response times. However, increasing the number of bases, up to a maximum of 22, shows significant improvements in population coverage, especially when aiming for a 10‐min response time. Suggestions for future research include calculating the exact number of rescue vehicles needed to optimize the service and considering cost implications. This study highlights the importance of enhancing the emergency response system to meet the needs of the population.

A bstract The rare electromagnetic J/ψ → μ ⁺ μ − μ ⁺ μ − decay is observed with a significance greatly exceeding the discovery threshold, using proton-proton collision data collected by the LHCb experiment during 2016–2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5 . 4 fb − 1 . The rate of this decay is measured relative to that of the J/ψ → μ ⁺ μ − mode. Using the QED model for the four-muon decay in the efficiency estimation, its branching fraction is determined to be $\mathcal{B}\left(J/\psi \to {\mu}^{+}{\mu}^{-}{\mu}^{+}{\mu}^{-}\right)=\left(1.13\pm 0.10\pm 0.05\pm 0.01\right)\times {10}^{-6},$ B J / ψ → μ + μ − μ + μ − = 1.13 ± 0.10 ± 0.05 ± 0.01 × 10 − 6 , where the uncertainties are statistical, systematic and due to the uncertainty on the branching fraction of the J/ψ → μ ⁺ μ − decay.

Charmonium production cross-section in proton–proton collisions is measured at the centre-of-mass energy $\sqrt{s}=13\,\textrm{TeV}$ s = 13 TeV using decays to $p\bar{p}$ p p ¯ final state. The study is performed using a data sample corresponding to an integrated luminosity of $2.2\,\textrm{fb}^{-1}$ 2.2 fb - 1 collected in 2018 with the $\text{ LHCb }$ LHCb detector. The production cross-section of the $\eta _c$ η c meson is measured in a rapidity range of $2.0< y < 4.0$ 2.0 < y < 4.0 and in a transverse momentum range of $5.0< p_{\textrm{T}} < 20.0\,\textrm{GeV}\!/\!{ c}$ 5.0 < p T < 20.0 GeV / c , which is extended compared with previous $\text{ LHCb }$ LHCb analyses. The differential cross-section is measured in bins of $p_\mathrm{{T}}$ p T and, for the first time, of y . Upper limits, at 90% and 95% confidence levels, on the $\eta _c(2S)$ η c ( 2 S ) and $h_c(1P)$ h c ( 1 P ) prompt production cross-sections are determined for the first time.

We investigated the influence of chronotype on eating habits among adolescents attending schools with morning (07:00 hours–12:00 hours) or afternoon (13:00 hours–18:00 hours) shifts, hypothesizing that incompatibility of study schedules may be related to dietary choices. In this cross‐sectional study, 734 adolescents (aged 14–19 years) completed an online questionnaire covering eating habits, chronotype, sleep duration, social jet lag, socioeconomic data, physical activity and anthropometric measures. Odds ratios with 95% confidence intervals were estimated using adjusted logistic regression, stratified by study shift. In the morning shift, a morning chronotype was associated with higher odds of breakfast (odds ratio: 3.47; 95% confidence interval: 1.13–10.71) compared with an evening chronotype. Both morning and intermediate chronotypes were associated with higher odds of morning snack (odds ratio: 3.52; 95% confidence interval: 1.13–10.93; and odds ratio: 2.87; 95% confidence interval: 1.18–6.99) and lower odds of fast foods (odds ratio: 0.09; 95% confidence interval: 0.02–0.49; and odds ratio: 0.19; 95% confidence interval: 0.58–0.62). In the afternoon shift, a morning chronotype was associated with higher odds of breakfast (odds ratio: 5.22; 95% confidence interval: 1.85–14.72), beans (odds ratio: 3.57; 95% confidence interval: 1.19–10.74), vegetables (odds ratio: 3.52; 95% confidence interval: 1.28–9.69) and fruits (odds ratio: 4.50; 95% confidence interval: 1.55–13.07) compared with an evening chronotype. Intermediate chronotype was associated with higher odds of breakfast (odds ratio: 3.71; 95% confidence interval: 2.03–6.77), morning snacks (odds ratio: 2.45; 95% confidence interval: 1.09–5.50), vegetables (odds ratio: 1.92; 95% confidence interval: 1.03–3.58) and fruits (odds ratio: 2.50; 95% confidence interval: 1.27–4.89), and lower odds of high‐energy intake post‐dinner (odds ratio: 0.43; 95% confidence interval: 0.22–0.85). Adolescents with an evening chronotype had lower odds of having breakfast. Both chronotype and study shifts influenced specific food consumption habits.

A bstract Using pp collision data at $\sqrt{s}$ s = 13 TeV, recorded by the LHCb experiment between 2016 and 2018 and corresponding to an integrated luminosity of 5 . 4 fb − 1 , the forward-backward asymmetry in the pp → Z/γ * → μ ⁺ μ − process is measured. The measurement is carried out in ten intervals of the difference between the muon pseudorapidities, within a fiducial region covering dimuon masses between 66 and 116 GeV, muon pseudorapidities between 2 . 0 and 4 . 5 and muon transverse momenta above 20 GeV. These forward-backward asymmetries are compared with predictions, at next-to-leading order in the strong and electroweak couplings. The measured effective leptonic weak mixing angle is ${\sin}^2{\theta}_{\textrm{eff}}^{\ell }=0.23147\pm 0.00044\pm 0.00005\pm 0.00023,$ sin 2 θ eff ℓ = 0.23147 ± 0.00044 ± 0.00005 ± 0.00023 , where the first uncertainty is statistical, the second arises from systematic uncertainties associated with the asymmetry measurement, and the third arises from uncertainties in the fit model used to extract ${\sin}^2{\theta}_{\textrm{eff}}^{\ell }$ sin 2 θ eff ℓ from the asymmetry measurement. This result is based on an arithmetic average of results using the CT18, MSHT20, and NNPDF31 parameterisations of the proton internal structure, and is consistent with previous measurements and with predictions from the global electroweak fit.

Resumo Este artigo focaliza disputas entre professores identificados com a área de Matemática e docentes ligados à Educação Matemática na Licenciatura em Matemática da Universidade Federal de São João del-Rei (UFSJ), em uma investigação sobre esse curso no período 2001-2019. Tais disputas pelo espaço de formação de professores foram evidenciadas em entrevistas com docentes da área de Educação Matemática do curso, realizadas com a metodologia da História Oral. Dois temas principais envolveram as disputas: as vagas docentes e a distribuição de disciplinas do curso. No âmbito dessas disputas, observaram-se tentativas de discriminação de gênero e segregação da área de Educação Matemática. Concluímos que o curso estudado é um espaço generificado, por terem se tornado nítidas as relações entre gênero e poder.

The quantum-walk-based spatial search problem aims to find a marked vertex using a quantum walk on a graph with marked vertices. We describe a framework for determining the computational complexity of spatial search by continuous-time quantum walk on arbitrary graphs by providing a recipe for finding the optimal running time and the success probability of the algorithm. The quantum walk is driven by a Hamiltonian derived from the adjacency matrix of the graph modified by the presence of the marked vertices. The success of our framework depends on the knowledge of the eigenvalues and eigenvectors of the adjacency matrix. The spectrum of the Hamiltonian is subsequently obtained from the roots of the determinant of a real symmetric matrix M , the dimensions of which depend on the number of marked vertices. The eigenvectors are determined from a basis of the kernel of M . We show each step of the framework by solving the spatial searching problem on the Johnson graphs with a fixed diameter and with two marked vertices. Our calculations show that the optimal running time is $O(\sqrt {N})$ with an asymptotic probability of 1 + o (1), where N is the number of vertices.

A bstract : The radiative decays χ c1 (3872) → ψ(2S) γ and χ c1 (3872) → J/ψγ are used to probe the nature of the χ c1 (3872) state using proton-proton collision data collected with the LHCb detector, corresponding to an integrated luminosity of 9 fb − 1 . Using the B ⁺ → χ c1 (3872)K ⁺ decay, the χ c1 (3872) → ψ(2S) γ process is observed for the first time and the ratio of its partial width to that of the χ c1 (3872) → J/ψγ decay is measured to be \frac{\Gamma_{\chi_{c1}(3872)\to \uppsi \left(2\textrm{S}\right)\gamma }}{\Gamma_{\chi_{c1}(3872)\to \textrm{J}/\uppsi \gamma }}=1.67\pm 0.21\pm 0.12\pm 0.04, Γ χ c 1 3872 → ψ 2 S γ Γ χ c 1 3872 → J / ψ γ = 1.67 ± 0.21 ± 0.12 ± 0.04 , where the first uncertainty is statistical, the second systematic and the third is due to the uncertainties on the branching fractions of the ψ(2S) and J/ψ mesons. The measured ratio makes the interpretation of the χ c1 (3872) state as a pure D ⁰ ${\overline{\textrm{D}}}^{\ast 0}$ D ¯ ∗ 0 + ${\overline{\textrm{D}}}^0$ D ¯ 0 D *0 molecule questionable and strongly indicates a sizeable compact charmonium or tetraquark component within the χ c1 (3872) state.

Asphaltene aggregation mechanism is still a nebulous and controversial issue. Many authors argue that the aggregation of its components is due to p-stacking interactions, nonetheless, alkyl chains, heteroatoms, and even acidic groups are also constituents of asphaltenes and can play an important role in the chemistry of asphaltene. Excimers from pyrene are easily detected by fluorescence and were used in the current study to probe the effect of the side chain on the p-stacking capacity of pyrene. Pyrene was acylated with acyl chains varying from two to twelve carbon atoms, and the effect of the variation of the acyl chain length on excimer formation was followed by fluorescence emission spectroscopy. The results revealed that as the side chain grows from two to twelve carbon atoms the excimer/monomer ratio decreases and the excimer heat of formation drops from DH = -6.00 to -1.29 kcal mol-1. Further, the crystal structure of octanoyl pyrene (PC8) indicates that in the crystal structure, the aromatic moiety faces the acyl chain. This result was corroborated by density functional theory (DFT) calculations. Finally, the results were compared with two different asphaltenes and indicate that p-stacking cannot be assumed as the main driving force for asphaltene aggregation.