Meson-photon transition form factors and resonance cross-sections in e+e−e^+ e^- collisions

Meson--photon--photon transition form factors for S-, P-, and D-wave states are calculated, the meson being treated as a non-relativistic heavy-quark--antiquark pair. The full dependence on both photon virtualities is included. Cross-section formulas for charge-conjugation even mesons with J^P = 0^-, 0^+, 1^+, 2^+, and 2^- in electron--positron collisions are presented and numerical results for LEP energies are given. In particular, we find two-photon event rates for \chi_{\rc 1}, \eta_{\rc}(2S), and \eta_{\rb}(1S) within reach of LEP. With minor modifications to incorporate SU(3)-flavour breaking we estimate rates for 18 light mesons as well, based on the observation that their two-photon decay widths agree remarkably well with measured data. Finally we point out that e^+ e^- cross sections for 1^+ states do not vanish at low Q^2, the Landau--Yang suppression factors of the two-photon cross sections being compensated by the photon propagators

Effect of flood basalt stratigraphy on seismic waveforms recorded offshore Faroe Islands

The generation of short-period multiples between highly heterogeneous layers of basalt flows can strongly alter transmitted seismic wavefields. These layers filter and modify penetrating waves, producing apparent attenuation and phase changes in the observed waveforms. We investigated the waveform and apparent phase changes of the primary seismic signal using mainly the maximum kurtosis approach. We compared the seismic recordings from two short-offset vertical seismic profiles (VSPs) with synthetic seismograms, generated from sonic logs in the same wells, and we found that short-period multiples cause a rapid broadening of the primary arrivals and strong apparent phase changes within a short depth interval below the top of the basalt flows. Relatively large uncertainties were associated with estimating constant phase shifts of the seismic arrivals within the topmost 250 m of the basalt sequences, where complex scattering occurred. Within this interval of the Brugdan I well, a phase-only compensation of the first arrivals with a frequency-independent, combined scattering, and intrinsic attenuation operator was unfeasible. At a greater depth, we found that the phase shifts, predicted by a VSP-derived effective Q value, were similar to those estimated from the VSP signals using the kurtosis method. Thus, phase-only compensation with a combined scattering and intrinsic attenuation operator could work well depending on the seismic signal bandwidth and the distribution, depth, and magnitude of the impedance contrasts in the basalt sequence

Experimental study of flow deflectors designed to alleviate ground winds induced by exhaust of 80-by 120-foot wind tunnel

An experimental study directed at finding a deflector ramp that will reduce to an acceptable level the ground winds under the exhaust jet of the 80 by 120 Foot Wind Tunnel at NASA Ames Center is described. A one-fifieth scale model of the full-scale facility was used to investigate how the jet flow field was modified by the various design parameters of the ramp. It was concluded that the ground winds were alleviated sufficiently by a ramp with end plates located next to the wind tunnel building along the ground edge of the exhaust opening. At full scale, the ramp should have a slant length of 7.62 m (25 ft) or more, and would be elevated at about 45 degrees to the ground plane. The material should have holes less than 15.2 (6 in) in diameter distributed uniformly over its surface to produce a porosity of about 30%

Spectroscopic Abundances of Solar-Type Dwarfs in the Open Cluster M34 (NGC 1039)

Parameters and relative abundances of Fe, Ni, Ti, Cr, Ca, Si, Al, and Mg have been derived for nine M34 G and K dwarfs from high-resolution, modest signal-to-noise ratio Keck HIRES spectra. Effective temperatures have been derived spectroscopically and fall in the range 4750 K Teff 6130 K. Despite modest scatter in Fe, Ti, Cr, Ca, Al, and Mg (none of which is found to be correlated with Li scatter in M34), our two coolest stars are slightly though consistently underabundant in these elements relative to the warmer stars. The two cool stars are slightly overabundant in Si, whose abundances are derived from higher excitation lines. This and our finding that Fe ii–based abundances are significantly higher than Fe i–based values in the cool stars seem to point toward the action of non-LTE effects (overionization, overexcitation, or both), though additional analysis is required to exclude inadequacies in the model atmospheres. Final mean cluster abundances are based on five warm stars, which indicate [Fe/H] = +0.07 Æ0.04, and are void of any statistically significant scatter. The other elements scale well with Fe except for Ni, which appears to be slightly underabundant with respect to Fe. Potassium abundances are derived and show a surprising marked trend with temperature, which further supports our suspicion of the presence of non-LTE effects. Moreover, similar trends with temperature suggest that the Li and K underabundances in cool M34 dwarfs are partially related; thus, some portion of the well-known Li-Teff trend in cool M34 dwarfs may be illusory

Procedures to select priority areas for payment for ecosystem services programs.

This work was developed in order to contribute to the application of principles of ecosystem ser-vices in decision-making for water resources management. It aims to identify procedures and meth-odologies used for decision-making in order to select priority areas to be included in projects or programs of compensation for ecosystem services. To do so, methods and experiences to select pri-ority areas were sought in the technical and scientific literature; the key steps used in the selection process of priority areas were identified; then a survey of the procedures adopted to each key step was done considering the literature selected; and, finally, the information collected was analyzed and classified. The results we found showed the main objectives, actions and criteria used to select priority areas for compensation for ecosystem services programs or projects. They also indicate the pressing need for these projects or programs to systematize and share their experiences in this are

Índices de agregação e teor de carbono intra-agregados como indicadores de qualidade do solo.

Esse trabalho teve por objetivo avaliar diferentes índices de agregação e teores de carbono em diferentes classes de agregados como ferramenta de diagnóstico de qualidade da estrutura do solo. O estudo foi realizado em uma microbacia localizada no Município de São Francisco de Itabapoana-RJ. Foram estudados três usos da terra: uma sucessão de abacaxi-aipim; um pastoreio-rotacionado e um remanescente de mata (referência), todos sob Latossolo Amarelo. Utilizou-se estatística multivariada (análise discriminante e canônica) para seleção dos índices que melhor indicam as mudanças na estrutura do solo e teste Dunnett para comparação de médias dos índices e do carbono em agregados. A mata e o pastoreio-rotacionado apresentaram os valores mais altos para as variáveis: Diâmetro Médio Ponderado (DMP), Diâmetro Médio Geométrico (DMG) e Índice de Estabilidade de Agregados (IEA), sendo respectivamente 2,94 mm, 2,83 mm, 92% e 2,92 mm, 2,75 mm, 91%. A sucessão de abacaxi-aipim apresentou os menores valores para esses índices, sendo 2,22 mm, 0,95 mm, 58% respectivamente. As variáveis que foram as melhores discriminantes para a estrutura e qualidade do solo foram a relação macro/microagregados e carbono intra-agregado, denotando a sensibilidade do C, tanto do macro quanto do microagregado da sucessão de culturas frente à mata (referência).bitstream/item/139866/1/BPD-250-Indice-Agregacao-Qualidade-Solos.pd

Modelagem da dinâmica do uso e ocupação do solo (1975 a 2010) na bacia do Rio Uberaba, Município de Veríssimo - MG.

Este trabalho teve por objetivo testar um modelo de simulação da dinâmica do uso e ocupação do solo, no período de 1975 a 2010, no trecho da bacia do Rio Uberaba situado no Município de Veríssimo, MG. Para a modelagem utilizou-se o módulo Land Change Modeler (LCM) pertencente ao SIG Idrisi Selva. As classes de uso e ocupação do solo analisadas foram: Mata, Agricultura e Pastagem. Houve um ligeiro aumento na área de mata no ano de 2010 devido à recomposição vegetal, enquanto a pastagem tornouse o principal uso, com o ganho de novas áreas onde substituiu a agricultura. Por sua vez, a agricultura apresentou as maiores perdas em área no período. Uma tentativa de prognóstico de uso da terra com o LCM para 2050 não obteve resultados conclusivos, pois o modelo utilizado, com base nas Cadeias de Markov, assume as transições como processos estacionários

Testing Quarkonium Production with Photoproduced J/ψ+γJ/\psi + \gamma

I compute the leading color-octet contributions to the process $\gamma + p \to J/\psi + \gamma (+ X)$ within the non-relativistic QCD (NRQCD) factorization formalism. In the color-singlet model, $J/\psi + \gamma$ can only be produced when the photon interacts through its structure function, while the color-octet mechanism allows for production of $J/\psi + \gamma$ via direct photon-gluon fusion. Resolved photon processes can be easily be distinguished from direct photon processes by examining the fraction of the incident photon energy carried away by the $J/\psi$ in the event. Therefore, this process provides a conclusive test of the color-octet mechanism. $J/\psi + \gamma$ production is particularly sensitive to the NRQCD matrix element which figures prominently in the fragmentation production of $J/\psi$ at large $p_{\perp}$ in hadron colliders. I also examine the predictions of the color evaporation model (CEM) of quarkonium production and find that this process can easily discriminate between the NRQCD factorization formalism and the CEM.Comment: uses Revtex, 12 pages, 4 EPS figures embedded using epsf.sty. Some references have been added. Version accepted for publication in Phys. Rev.