Small-scale gold mining and the COVID-19 pandemic: Conflict and cooperation in the Brazilian Amazon

The COVID-19 pandemic exposes both conflict and cooperation in artisanal and small-scale gold mining in the Brazilian Amazon. Reporting on the experiences of artisanal and small-scale gold miners (garimpeiros, in Brazilian Portuguese), we show how, on the one hand, the pandemic challenges an already precarious working system that could lead garimpeiros, often invisible to public policies, to positions of further vulnerability; and, on the other hand, highlights the capacity of garimpeiros to self-organize and navigate the difficulties by finding alternative solutions to cope with the crisis. This leads us to argue that emerging strategies of cooperation, related to self-organization and communication channels have the potential to provide experiences useful for processes of conflict transformation in the post-crisis. We acknowledge that much depends on the severity of the crisis and its manifestations in the region; nevertheless, the potential for constructive outcomes from the crisis should not be disregarded

Optical And Esr Study Of Er3+ In Linbo3

We report laser-excited optical transitions between the 4S3/2 and 4I15/2 multiplets of Er3+ as an impurity in the LiNbO3 host, together with the optical-absorption spectra at liquid-helium and liquid-nitrogen temperatures. The optical data allow us to determine the crystal-field splittings of those levels and the spin-Hamiltonian parameters for the 4I15/2 lower multiplet. The observed electron-spin resonance and the angular variation of this spectrum agree with the parameters obtained by optical techniques. Both techniques show that only one of the three possible trigonal sites in LiNbO3 is occupied by Er3+ within the experimental sensitivity, in agreement with recent x-ray standing-wave measurements. © 1995 The American Physical Society.5153206320

Effect Of Etching Time And Light Source On The Bond Strength Of Metallic Brackets To Ceramic

This study evaluated the bond strength of brackets to ceramic testing different etching times and light sources for photo-activation of the bonding agent. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 20 or 60 s. After application of silane on the ceramic surface, metallic brackets were bonded to the cylinders using Transbond XT (3M Unitek). The specimens for each etching time were assigned to 4 groups (n=15), according to the light source: XL2500 halogen light, UltraLume 5 LED, AccuCure 3000 argon laser, and Apollo 95E plasma arc. Light-activation was carried out with total exposure times of 40, 40, 20 and 12 s, respectively. Shear strength testing was carried out after 24 h. The adhesive remnant index (ARI) was evaluated under magnification. Data were subjected to two-way ANOVA and Tukey's test (α=0.05). Specimens etched for 20 s presented significantly lower bond strength (p0.05) were detected among the light sources. The ARI showed a predominance of scores 0 in all groups, with an increase in scores 1, 2 and 3 for the 60 s time. In conclusion, only the etching time had significant influence on the bond strength of brackets to ceramic.223245248Barghi, N., Fischer, D.E., Vatani, L., Effects of porcelain leucite content, types of etchants, and etching time on porcelaincomposite bond (2006) J Esthet Restor Dent, 18, pp. 47-52Nagayassu, M.P., Shintome, L.K., Uemura, E.S., Araújo, J.E., Effect of surface treatment on the shear bond strength of a resin-based cement to porcelain (2006) Braz Dent J, 17, pp. 290-295Shimada, Y., Yamaguchi, S., Tagami, J., Micro-shear bond strength of dual-cured resin cement to glass ceramics (2002) Dent Mater, 18, pp. 380-388Chen, J.H., Matsumura, H., Atsuta, M., Effect of different etching periods on the bond strength of a composite resin to a machinable porcelain (1998) J Dent, 26, pp. 53-58Guler, A.U., Yilmaz, F., Yenisey, M., Guler, E., Ural, C., Effect of acid etching time and a self-etching adhesive on the shear bond strength of composite resin to porcelain (2006) J Adhes Dent, 8, pp. 21-25Kasuya, K., Miyazaki, Y., Ogawa, N., Maki, K., Manabe, A., Itoh, K., Efficacy of experimental dual-cure resin cement for orthodontic direct bond system (2006) Orthod Waves, 65, pp. 107-111Meguro, D., Hayakawa, T., Kasai, K., Efficacy of using orthodontic adhesive resin in bonding and debonding characteristics of a calcium phosphate ceramic bracket (2006) Orthod Waves, 65, pp. 148-154Dall'igna, C.M., Marchioro, E.M., Spohr, A.M., Mota, E.G., Effect of curing time on the bond strength of a bracket-bonding system cured with a light-emitting diode or plasma arc light (2011) Eur J Orthod, 33, pp. 55-59Correr, A.B., Sinhoreti, M.A., Sobrinho, L.C., Tango, R.N., Schneider, L.F., Consani, S., Effect of the increase of energy density on Knoop hardness of dental composites light-cured by conventional QTH, LED and xenon plasma arc (2005) Braz Dent J, 16, pp. 218-224Cekic-Nagas, I., Egilmez, F., Ergun, G., The effect of irradiation distance on microhardness of resin composites cured with different light curing units (2010) Eur J Dent, 4, pp. 440-446Thind, B.S., Stirrups, D.R., Lloyd, C.H., A comparison of tungstenquartz- halogen, plasma arc and light-emitting diode light sources for the polymerization of an orthodontic adhesive (2006) Eur J Orthod, 28, pp. 78-82Filipov, I.A., Vladimirov, S.B., Residual monomer in a composite resin after light-curing with different sources, light intensities and spectra of radiation (2006) Braz Dent J, 17, pp. 34-38Park, J.K., Hur, B., Ko, C.C., García-Godoy, F., Kim, H.I., Kwon, Y.H., Effect of light-curing units on the thermal expansion of resin nanocomposites (2010) Am J Dent, 23, pp. 331-334Price, R.B., Labrie, D., Rueggeberg, F.A., Felix, C.M., Irraciance differences in the violet (405 nm) and blue (460 nm) spectral ranges among dental light-curing units (2010) J Esthet Restor Dent, 22, pp. 363-377Yen, T.W., Blackman, R.B., Baez, R.J., Effect of acid etching on the flexural strength of a feldspathic porcelain and a castable glass ceramic (1993) J Prosthet Dent, 70, pp. 224-233Reynolds, I.R., Composite filling materials as adhesives in orthodontics (1975) Br Dent J, 138, p. 83Rueggeberg, F., Contemporary issues in photocuring (1999) Compend Contin Educ Dent, (SUPPL.), pp. 4-15Olsen, M.E., Bishara, S.E., Boyer, D.B., Jakobsen, J.R., Effect of varying etching times on the bond strength of ceramic brackets (1996) Am J Orthod Dentofacial Orthop, 109, pp. 403-409Sant'anna, E.F., Monnerat, M.E., Chevitarese, O., Stuani, M.B., Bonding brackets to porcelain - in vitro study (2002) Braz Dent J, 3, pp. 191-196Canay, S., Hersek, N., Ertan, A., Effect of different acid treatments on a porcelain surface (2001) J Oral Rehabil, 28, pp. 95-10

Ligand-Free Palladium-Catalyzed Oxyarylation of Dihydronaphthal­enes and Chromenequinone with o-Iodophenols and 3-Iodolawsone in PEG-400: An Efficient Synthesis of 5-Carbapterocarpans and Pterocarpanquinones

Dihydronaphthalenes were oxyarylated with o-iodophenols, in PEG-400 at 140 or 170 °C, leading regio- and stereoselectively to 5-carbapterocarpans. By using Pd(OAc)2 (5–10 mol%) as precatalyst and Ag2CO3 (1.1 equiv) as base (conditions A), products were obtained in good to excellent chemical yields, in 5–30 minutes, irrespective of the pattern of substitution the starting materials. Alternatively, when p-hydroxyacetophenone oxime derived palladacycle (1 mol%) was used as precatalyst, and dicyclohexylamine (2 equiv) was used as base (silver-free, conditions B), the corresponding adducts were obtained in moderate to good yields, in 0.5 to 4 hours. Finally, the oxyarylation of dihydronaphthalenes­ and chromenquinone with o-iodophenols and 3-iodolawsone in PEG-400 under conditions A led regio- and stereoselectively to the formation of carbapterocarpanquinones and pterocarpanquinones in moderate yield.Financial support from Brazilian agencies CAPES-DGU (Project 200/09), CNPq, FAPERJ and UFRJ are acknowledged. Spanish MICINN (Projects PHB2008-0037-PC, CTQ2007-62771/BQU, CTQ2010-20387, Consolider INGENIO 2010 CSD2007-00006), FEDER, Generalitat Valenciana (Project PROMETEO/2009/038), and the University of Alicante are acknowledged

Vascular Flora Of The Legado Das Águas, Reserva Votorantim, Municipalities Of Tapiraí, Miracatú And Juquiá, São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)We present a list of vascular plants found in Legado das Águas, Reserva Votorantim, a private reserve having an area of approximately 35,000 ha that spans the municipalities of Tapiraí, Miracatú, and Juquiá, in the state of São Paulo, Brazil. The reserve is part of a complex of state-protected areas including Alto Ribeira Touristic State Park, Intervales State Park, Carlos Botelho State Park, Jurupará State Park, and Serra do Mar State Park. Together, these form an important and large area of continuous and well-preserved forest. Our study, which involved two main floristic surveys in March/April 2013 and April 2014, recorded 768 species, representing 131 families and 432 genera. The majority of species were angiosperms (619) representing 106 families and 370 genera. There were also two species of gymnosperms belonging to two genera in separate families; 147 species of ferns and lycophytes belonging to 23 families and 60 genera. In demonstrating the presence of almost 800 species of plants, of which 16 are threatened, our study highlights the importance of floristic surveys and the critical role of private protected areas in managing and preserving native flora. © 2016 Check List and Authors.1262011/22923-8, FAPESP, Fundação de Amparo à Pesquisa do Estado de São Paulo2015/9444-4, FAPESP, Fundação de Amparo à Pesquisa do Estado de São PauloFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter