Etnomatemática Do Sistema De Contagem Guarani Das Aldeias Itaty, Do Morro Dos Cavalos, E M'biguaçu

The Guarani are one of several indigenous Brazilian tribes. Since the first Portuguese colonizers arrived to Brazil, the culture and costumes - including mathematical knowledge - and practices of Guarani and other indigenous people were considered inferior and unworthy. Considering this panorama and taking into account the multicultural features of Brazilian school, we present this article with the objective of analyzing the counting system and some graphical symbols of two Guarani tribes, the Itaty tribe, settled at the "Morro dos Cavalos" and M'Biguaçu tribe, located between the cities Palhoça and Biguaçu in Santa Catarina State, Brazil. This ethnographic case study was carried out through interviews with leaders of the Guarani tribes mentioned above. The present study is based on the theoretical principles of the "Ethnomatematics Program". The results of our analyses made evident that the counting system as well as the symbols employed are strongly correlated to these people's culture, thus playing roles both in quantification and in what we call in this paper as qualitative function.3056992101

Registros novos e adicionais de Agalliinae, Gyponinae e Nirvaniinae (Homoptera: Cicadellidae) para o Estado de Minas Gerais, Brasil

Coelho LBN, Da-Silva ER, Ferreira PSF. 2001. Registros novos e adicionais de Agalliinae, Gyponinae e Nirvaniinae (Homoptera: Cicadellidae) para o Estado de Minas Gerais, Brasil. Entomotropica 16(2):131-135 . Agallia alvarengai , A. configurata, A. cucata, Agalliopsis ornaticollis (Agalliinae), Curtara antica , C. atomaria, Gypona validana , Hecalapona ferosa (Gyponinae) e Neonirvana hyalina (Nirvaniinae) s\ue3o pela primeira vez registradas para o Estado de Minas Gerais, Brasil. Agallia albidula , A. cezia (Agalliinae) e Acuera gloma (Gyponinae) s\ue3o pela primeira vez registradas para o munic\uedpio de Vi\ue7osa.Coelho LBN, Da-Silva ER, Ferreira PSF. 2001. New and additional records of Agalliinae, Gyponinae e Nirvaniinae (Homoptera: Cicadellidae) from State of Minas Gerais, Brazil. Entomotropica 16(2):131-135. Agallia alvarengai , A. configurata, A. cucata, Agalliopsis ornaticollis (Agalliinae), Curtara antica , C. atomaria, Gypona validana , Hecalapona ferosa (Gyponinae) and Neonirvana hyalina (Nirvaniinae) are for the first time recorded from Minas Gerais State, Brazil. Agallia albidula , A. cezia (Agalliinae) and Acuera gloma (Gyponinae) are for the first time recorded from the county of Vi\ue7osa

Understanding the Influence of the Biomass-Derived Alcohols on the Activity and Stability of Pt Nanoparticles Supported on Graphene Nanoribbons

We produced Pt/GNRs by a one-step synthesis procedure and evaluated their electroactivity and stability towards glycerol electrooxidation reaction (GEOR) for the first time. We compared the electrocatalytic performance of GEOR with methanol and ethanol electrooxidation on Pt/GNRs at identical experimental conditions. The activities and stabilities for the electrooxidation of these biomass-derived alcohols on Pt/GNRs were compared to commercial Pt/C. The synthesis of the Pt/GNRs was confirmed by transmission electron microscopy, x-ray diffractometry, ultraviolet spectrophotometry, and Raman spectroscopy. We found that the activities of Pt/GNRs for these reactions are comparable to Pt/C, with improvement in terms of current density for methanol electrooxidation. Comparing potentiostatic measurements, we found that glycerol produces lower pseudo-stationary current densities than ethanol and methanol on both catalysts, with greatest values found for methanol electrooxidation on Pt/C. Otherwise, the GNRs remarkably enhance the stability of the catalyst for all the reactions, by increasing the stability of the current density during successive potential cycles, and by preventing the loss of electrochemically active surface area by avoiding carbon corrosion and Pt detachment. Moreover, we showed that the stability of the NPs depends on the biomass-derived alcohol used. The solution containing methanol reveals itself the most aggressive electrochemical environment to the catalyst, impacting in the decrease of surface area, while glycerol is less aggressive. Hence, the different products formed at the interface electrode/solution might lead to a different electrochemical environment, which plays an important role on the stability of the catalysts.The authors acknowledge financial assistance from CNPq (grant no. 454516/2014-2), FUNDECT (grant no. 026/2015), FAPESP (grant no. 2016/01365-0), CAPES, FINEP, and FAPESP.Peer reviewe

Interactive engagement in Introductory Physics at UFJF

In this paper we describe a series of changes to the teaching method of an undergraduate introductory physics course for physics majors at the Federal University of Juiz de Fora. The aim of the method is to foster interactive engagement. We analyze the effectiveness of instruction by measuring the normalized gain g for the Force Concept Inventory and compare it to previous semesters. We show an increase in g compared to traditional teaching methods.Neste trabalho descrevemos uma série de modificações no ensino de Física I para alunos do curso de Física da UFJF. Estas modificações introduziram um ambiente de engajamento interativo. Analisamos o sucesso do método aplicando o Force Concept Inventory e mostramos uma melhora do desempenho dos alunos, se comparados aos desempenhos típicos dos alunos em métodos convencionais

Growth model with restricted surface relaxation

We simulate a growth model with restricted surface relaxation process in d=1 and d=2, where d is the dimensionality of a flat substrate. In this model, each particle can relax on the surface to a local minimum, as the Edwards-Wilkinson linear model, but only within a distance s. If the local minimum is out from this distance, the particle evaporates through a refuse mechanism similar to the Kim-Kosterlitz nonlinear model. In d=1, the growth exponent beta, measured from the temporal behavior of roughness, indicates that in the coarse-grained limit, the linear term of the Kardar-Parisi-Zhang equation dominates in short times (low-roughness) and, in asymptotic times, the nonlinear term prevails. The crossover between linear and nonlinear behaviors occurs in a characteristic time t_c which only depends on the magnitude of the parameter s, related to the nonlinear term. In d=2, we find indications of a similar crossover, that is, logarithmic temporal behavior of roughness in short times and power law behavior in asymptotic times

Approaching a fully-polarized state of nuclear spins in a solid

Magnetic noise of atomic nuclear spins is a major source of decoherence in solid-state spin qubits. In theory, near-unity nuclear spin polarization can eliminate decoherence of the electron spin qubit, while turning the nuclei into a useful quantum information resource. However, achieving sufficiently high nuclear polarizations has remained an evasive goal. Here we implement a nuclear spin polarization protocol which combines strong optical pumping and fast electron tunneling. Nuclear polarizations well above 95% are generated in GaAs semiconductor quantum dots on a timescale of 1 minute. The technique is compatible with standard quantum dot device designs, where highly-polarized nuclear spins can simplify implementations of qubits and quantum memories, as well as offer a testbed for studies of many-body quantum dynamics and magnetism

Self-avoiding fractional Brownian motion - The Edwards model

In this work we extend Varadhan's construction of the Edwards polymer model to the case of fractional Brownian motions in $\R^d$, for any dimension $d\geq 2$, with arbitrary Hurst parameters $H\leq 1/d$.Comment: 14 page

Crossover effects in a discrete deposition model with Kardar-Parisi-Zhang scaling

We simulated a growth model in 1+1 dimensions in which particles are aggregated according to the rules of ballistic deposition with probability p or according to the rules of random deposition with surface relaxation (Family model) with probability 1-p. For any p>0, this system is in the Kardar-Parisi-Zhang (KPZ) universality class, but it presents a slow crossover from the Edwards-Wilkinson class (EW) for small p. From the scaling of the growth velocity, the parameter p is connected to the coefficient of the nonlinear term of the KPZ equation, lambda, giving lambda ~ p^gamma, with gamma = 2.1 +- 0.2. Our numerical results confirm the interface width scaling in the growth regime as W ~ lambda^beta t^beta, and the scaling of the saturation time as tau ~ lambda^(-1) L^z, with the expected exponents beta =1/3 and z=3/2 and strong corrections to scaling for small lambda. This picture is consistent with a crossover time from EW to KPZ growth in the form t_c ~ lambda^(-4) ~ p^(-8), in agreement with scaling theories and renormalization group analysis. Some consequences of the slow crossover in this problem are discussed and may help investigations of more complex models.Comment: 16 pages, 7 figures; to appear in Phys. Rev.

Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil.

The São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that orgThe São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity