Vitreous GeO2 response to shock loading

Shock wave profiles in vitreous GeO2 (6.56 Mg/m^3) under planar loading were measured using stress gauges to 14 GPa. New and previous data yield Hugoniot: D=0.974 (km/s)+1.711 u for shocks of 6 to 40 GPa. We show that the phase change from 4- to 6-fold coordination of Ge+4 with O–2 in vitreous GeO2 occurs from 4 to 15 GPa. Hugoniots of vitreous GeO2 and SiO2 are found to approximately coincide if the pressure in SiO2 is scaled by the ratio of SiO2 to GeO2 initial density

Spin effects in strong-field laser-electron interactions

The electron spin degree of freedom can play a significant role in relativistic scattering processes involving intense laser fields. In this contribution we discuss the influence of the electron spin on (i) Kapitza-Dirac scattering in an x-ray laser field of high intensity, (ii) photo-induced electron-positron pair production in a strong laser wave and (iii) multiphoton electron-positron pair production on an atomic nucleus. We show that in all cases under consideration the electron spin can have a characteristic impact on the process properties and their total probabilities. To this end, spin-resolved calculations based on the Dirac equation in the presence of an intense laser field are performed. The predictions from Dirac theory are also compared with the corresponding results from the Klein-Gordon equation.Comment: 9 pages, 6 figure

Influência do espaçamento na produção volumétrica e qualidade da madeira de Mimosa scabrella Benth. e Eucalyptus viminalis Labill.

bitstream/item/101160/1/PA-1983-Ahrens-InfluenciaEspacamentoProducao.pdf.pd

A previsão normativa para o pagamento por serviços ambientais no código florestal brasileiro.

Neste capítulo documenta-se uma análise introdutória acerca do tratamento propiciado ao pagamento por serviços ambientais (PSAs) no Código Florestal brasileiro, reformado com a edição da Lei nº 12.651/2012 (BRASIL, 2012). Em seu art. 41, aquela Lei estabelece que o poder público federal poderá instituir um programa de apoio e incentivo à conservação do meio ambiente, prevendo-se, no inciso I, a possibilidade de se promover PSAs como retribuição às atividades de conservação e melhoria de ecossistemas nos casos nominados: sistemas produtivos agrícolas. Todavia, são contemplados no inciso II, do mesmo artigo, que trata da obtenção de crédito agrícola, com taxas de juros menores, e da contratação de seguro agrícola em condições mais favoráveis que as praticadas no mercado. De outro lado, por se tratar de norma programática, e para que tenha efetividade, o art. 41 ainda requer regulamentação, o que se recomenda.Capítulo 31

Efeitos da primeira poda em povoamentos jovens de Pinus elliottii var elliottii, estabelecidos na região costeira do Rio Grande do Sul.

bitstream/item/101229/1/PA-1983-Ahrens-EfeitosPrimeira.pd

Efeitos da primeira poda em povoamentos jovens de Pinus taeda L. estabelecidos em Mafra, SC, região do alto rio negro.

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From AMANDA to IceCube

The first string of the neoteric high energy neutrino telescope IceCube successfully began operating in January 2005. It is anticipated that upon completion the new detector will vastly increase the sensitivity and extend the reach of AMANDA to higher energies. A discussion of the IceCube's discovery potential for extra-terrestrial neutrinos, together with the prospects of new physics derived from the ongoing AMANDA research will be the focus of this paper. Preliminary results of the first antarctic high energy neutrino telescope AMANDA searching in the muon neutrino channel for localized and diffuse excess of extra-terrestrial neutrinos will be reviewed using data collected between 2000 and 2003. Neutrino flux limits obtained with the all-flavor dedicated UHE and cascade analyses will be described. A first neutrino spectrum above one TeV in agreement with atmospheric neutrino flux expectations and no extra-terrestrial contribution will be presented, followed by a discussion of a limit for neutralino CDM candidates annihilating in the center of the Sun.Comment: 15 pages, 8 figures Invited talk contribution at 5th International Conference on Non-accelerator New Physics (NANP 05), Dubna, Russia, 20-25 Jun 200

Extremely energetic cosmic neutrinos: Opportunities for astrophysics, particle physics, and cosmology

Existing and planned observatories for cosmic neutrinos open up a huge window in energy from 10^7 to 10^17 GeV. Here, we discuss in particular the possibilities to use extremely energetic cosmic neutrinos as a diagnostic of astrophysical processes, as a tool for particle physics beyond the Standard Model, and as a probe of cosmology.Comment: 10 pages, 7 figures, ws-procs9x6.cls, talk presented at the ARENA Workshop, DESY, Zeuthen, Germany, May 17-19, 200