Super-Kamiokande data and atmospheric neutrino decay

Neutrino decay has been proposed as a possible solution to the atmospheric neutrino anomaly, in the light of the recent data from the Super-Kamiokande experiment. We investigate this hypothesis by means of a quantitative analysis of the zenith angle distributions of neutrino events in Super-Kamiokande, including the latest (45 kTy) data. We find that the neutrino decay hypothesis fails to reproduce the observed distributions of muons.Comment: 6 pages (RevTeX) + 2 figures (Postscript

Melhoramento genetico de mandioca.

Variedade de mandioca e um dos principais componentes para o desenvolvimento do sistema produtivo dessa cultura, alem de constituir uma tecnologia que nao implica em custos adicionais para o produtor. Apesar da mandioca apresentar um alto potencial produtivo, estimado por COCK (1974) em 90 t/ha/ano, a produtividade nacional esta em torno de 12 t/ha. Um dos fatores que tem contribuido para a baixa produtividade desse cultivo no Brasil, e o uso de variedades com baixo potencial produtivo. A demanda por novas variedades de mandioca vem crescendo constantemente, a medida que surgem novas alternativas de uso pelo produto, bem como a expansao de novas fronteiras agricolas para o plantio dessa cultura. Para atender essas demandas, e importante definir-se as caracteristicas que necessitam serem melhoradas em funcao do ecossistema, da finalidade de exploracao do cultivo, e principalmente dos criterios do produtor e do consumidor utilizados na adocao de variedades de mandioca. Segundo ROMERO (1992 a), e fundamental integrar as perspectivas do produtor e do melhorista no desenvolvimento de variedades para uma determinada regiao.bitstream/item/88954/1/Melhoramento-Genetico-de-mandiocaFUKUDAid6628.pdfApostila apresentada no 9 º. Curso Intensivo Nacional de Mandioc

Control of shock wave-boundary layer interactions by bleed in supersonic mixed compression inlets

An experimental investigation was conducted to determine the effect of bleed on a shock wave-boundary layer interaction in an axisymmetric mixed-compression supersonic inlet. The inlet was designed for a free-stream Mach number of 2.50 with 60-percent supersonic internal area contraction. The experiment was conducted in the NASA Lewis Research Center 10-Foot Supersonic Wind Tunnel. The effects of bleed amount and bleed geometry on the boundary layer after a shock wave-boundary layer interaction were studied. The effect of bleed on the transformed form factor is such that the full realizable reduction is obtained by bleeding of a mass flow equal to about one-half of the incident boundary layer mass flow. More bleeding does not yield further reduction. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise

Neutrino masses and mixing angles from leptoquark interactions

In this paper we show that the mixing between leptoquarks (LQ's) from different $SU(2)_l$ multiplets can generate a non-trivial Majorana mass matrix for neutrinos through one loop self energy diagrams. Such mixing can arise from gauge invariant and renormalizable LQ-Higgs interaction terms after EW symmetry breaking. We use the experimental indication on neutrino oscillation to find constraints on specific combinations of LQ couplings to quark-lepton pairs and to the SM higgs boson. These constraints are compared with the ones from $\pi\to e\bar {\nu}_e$.Comment: The expressions for majorana mass matrix of neutrinos have been corrected so that they are symmetric. Final version to be published in Physical Review

Seleção preliminar de germoplasma de mandioca nas condições de Petrolina.

Estudou-se a variabilidade genética de 999 acessos disponíveis no banco Ativo de Germoplama do CNPMF

Novos clones de mandioca para a os Tabuleiros Costeiros do Nordeste

bitstream/item/125319/1/Mandioca-ClonesNordeste.pd

Variabilidade genetica e melhoramento da mandioca (Manihot esculenta Crantz).

A cultura da mandioca constitui uma das mais importantes fontes de carboidratos nos trópicos, empregada na alimentação humana, animal e na indústria de processamento por cerca de 500 milhões de pessoas em todo o mundo. É cultivada em todo o território brasileir

Propagação rápida de mandioca no nordeste brasileiro.

bitstream/CPATC/19574/1/ct-45.pdfISSN 1678-1945

Searching for νμ→ντ\nu_\mu \to \nu_\tau Oscillations with Extragalactic Neutrinos

We propose a novel approach for studying $\nu_\mu \to \nu_\tau$ oscillations with extragalactic neutrinos. Active Galactic Nuclei and Gamma Ray Bursts are believed to be sources of ultrahigh energy muon neutrinos. With distances of 100 Mpc or more, they provide an unusually long baseline for possible detection of $\nu_\mu \to \nu_\tau$ with mixing parameters $\Delta m^2$ down to $10^{-17}$eV$^2$, many orders of magnitude below the current accelerator experiments. By solving the coupled transport equations, we show that high-energy $\nu_\tau$'s, as they propagate through the earth, cascade down in energy, producing the enhancement of the incoming $\nu_\tau$ flux in the low energy region, in contrast to the high-energy $\nu_\mu$'s, which get absorbed. For an AGN quasar model we find the $\nu_\tau$ flux to be a factor of 2 to 2.5 larger than the incoming flux in the energy range between $10^2$ GeV and $10^4$ GeV, while for a GRB fireball model, the enhancement is 10%-27% in the same energy range and for zero nadir angle. This enhancement decreases with larger nadir angle, thus providing a novel way to search for $\nu_\tau$ appearance by measuring the angular dependence of the muons. To illustrate how the cascade effect and the $\nu_\tau$ final flux depend on the steepness of the incoming $\nu_\tau$, we show the energy and angular distributions for several generic cases of the incoming tau neutrino flux, $F_\nu^0 \sim E^{-n}$ for n=1,2 and 3.6. We show that for the incoming flux that is not too steep, the signal for the appearance of high-energy $\nu_\tau$ is the enhanced production of lower energy $\mu$ and their distinctive angular dependence, due to the contribution from the $\tau$ decay into $\mu$ just below the detector.Comment: 11 pages, including 4 color figure