The IceCube neutrino observatory has established the existence of a flux of high-energy astrophysical neutrinos inconsistent with the expectation from atmospheric backgrounds at a significance ...greater than \(5\sigma\). This flux has been observed in analyses of both track events from muon neutrino interactions and cascade events from interactions of all neutrino flavors. Searches for astrophysical neutrino sources have focused on track events due to the significantly better angular resolution of track reconstructions. To date, no such sources have been confirmed. Here we present the first search for astrophysical neutrino sources using cascades interacting in IceCube with deposited energies as small as 1 TeV. No significant clustering was observed in a selection of 263 cascades collected from May 2010 to May 2012. We show that compared to the classic approach using tracks, this statistically-independent search offers improved sensitivity to sources in the southern sky, especially if the emission is spatially extended or follows a soft energy spectrum. This enhancement is due to the low background from atmospheric neutrinos forming cascade events and the additional veto of atmospheric neutrinos at declinations \(\lesssim-30^\circ\).
The origins of high-energy astrophysical neutrinos remain a mystery despite extensive searches for their sources. We present constraints from seven years of IceCube Neutrino Observatory muon data on ...the neutrino flux coming from the Galactic plane. This flux is expected from cosmic-ray interactions with the interstellar medium or near localized sources. Two methods were developed to test for a spatially-extended flux from the entire plane, both maximum likelihood fits but with different signal and background modeling techniques. We consider three templates for Galactic neutrino emission based primarily on gamma-ray observations and models that cover a wide range of possibilities. Based on these templates and an unbroken \(E^{-2.5}\) power-law energy spectrum, we set 90% confidence level upper limits constraining the possible Galactic contribution to the diffuse neutrino flux to be relatively small, less than 14% of the flux reported in Aartsen et al. (2015a) above 1 TeV. A stacking method is also used to test catalogs of known high energy Galactic gamma-ray sources.
We present a search for a light sterile neutrino using three years of atmospheric neutrino data from the DeepCore detector in the energy range of approximately \(10-60~\)GeV. DeepCore is the ...low-energy sub-array of the IceCube Neutrino Observatory. The standard three-neutrino paradigm can be probed by adding an additional light (\(\Delta m_{41}^2 \sim 1 \mathrm{\ eV^2}\)) sterile neutrino. Sterile neutrinos do not interact through the standard weak interaction, and therefore cannot be directly detected. However, their mixing with the three active neutrino states leaves an imprint on the standard atmospheric neutrino oscillations for energies below 100 GeV. A search for such mixing via muon neutrino disappearance is presented here. The data are found to be consistent with the standard three neutrino hypothesis. Therefore we derive limits on the mixing matrix elements at the level of \(|U_{\mu4}|^2 < 0.11 \) and \(|U_{\tau4}|^2 < 0.15 \) (90% C.L.) for the sterile neutrino mass splitting \(\Delta m_{41}^2 = 1.0\) eV\(^2\).
IceCube is a neutrino observatory deployed in the glacial ice at the
geographic South Pole. The $\nu_\mu$ energy unfolding described in this paper
is based on data taken with IceCube in its 79-string ...configuration.
A sample of muon neutrino charged-current interactions with a purity of
99.5\% was selected by means of a multivariate classification process based on
machine learning. The subsequent unfolding was performed using the software
\truee. The resulting spectrum covers an E$_\nu$-range of more than four orders
of magnitude from 125 GeV to 3.2 PeV. Compared to the Honda atmospheric
neutrino flux model, the energy spectrum shows an excess of more than
$1.9\,\sigma$ in four adjacent bins for neutrino energies
$E_\nu\geq177.8$\,TeV. The obtained spectrum is fully compatible with previous
measurements of the atmospheric neutrino flux and recent IceCube measurements
of a flux of high-energy astrophysical neutrinos.
We present the first full-sky analysis of the cosmic ray arrival direction distribution with data collected by the High-Altitude Water Cherenkov and IceCube observatories in the northern and southern ...hemispheres at the same median primary particle energy of 10 TeV. The combined sky map and angular power spectrum largely eliminate biases that result from partial sky coverage and present a key to probe into the propagation properties of TeV cosmic rays through our local interstellar medium and the interaction between the interstellar and heliospheric magnetic fields. From the map, we determine the horizontal dipole components of the anisotropy δ 0h = 9.16 × 10−4 and δ 6h = 7.25 × 10−4 (±0.04 × 10−4). In addition, we infer the direction (2292 ± 35 R.A., 114 ± 30 decl.) of the interstellar magnetic field from the boundary between large-scale excess and deficit regions from which we estimate the missing corresponding vertical dipole component of the large-scale anisotropy to be .
IceCube is a neutrino observatory deployed in the glacial ice at the geographic South Pole. The \(\nu_\mu\) energy unfolding described in this paper is based on data taken with IceCube in its ...79-string configuration. A sample of muon neutrino charged-current interactions with a purity of 99.5\% was selected by means of a multivariate classification process based on machine learning. The subsequent unfolding was performed using the software \truee. The resulting spectrum covers an E\(_\nu\)-range of more than four orders of magnitude from 125 GeV to 3.2 PeV. Compared to the Honda atmospheric neutrino flux model, the energy spectrum shows an excess of more than \(1.9\,\sigma\) in four adjacent bins for neutrino energies \(E_\nu\geq177.8\)\,TeV. The obtained spectrum is fully compatible with previous measurements of the atmospheric neutrino flux and recent IceCube measurements of a flux of high-energy astrophysical neutrinos.
Reaction of melon genotypes to the gummy stem blight and the downy mildew Santos, Gil R dos(Universidade Federal do Tocantins); Castro Neto, Manoel D de(Universidade Federal do Tocantins); Ramos, Leandro N(UnB Depto Fitopatologia) ...
Horticultura brasileira,
06/2009, Volume:
27, Issue:
2
Magazine Article
Peer reviewed
Open access
The gummy stem blight (Didymella bryoniae) and the downy mildew (Pseudoperonospora cubensis) are two foremost melon (Cucumis melo) diseases, considering their effects on yield and fruit quality. ...Despite the importance of such diseases, relatively few studies have been done so far on the identification of resistance sources to D. bryoniae and P. cubensis in Brazil. This work aimed at evaluating the resistance of commercial melon genotypes to the gummy stem blight and the downy mildew. Firstly, the most aggressive and representative D. bryoniae isolate was selected. Subsequently, the resistance of 86 melon genotypes to stem infection was studied upon greenhouse conditions by inoculating with the previously selected isolate. Afterwards, the resistance to mildew and leaf infection by D. bryoniae of 28 melon genotypes was evaluated in the field, under natural infection. In the greenhouse, all 86 melon genotypes were infected and showed stem infection symptoms caused by D. bryoniae four days after inoculation. Nevertheless, a significant variation on the resistance levels of the melon genotypes was found. Under field conditions and natural inoculation, genotypes Taslaki and Sary Juliabi were the most susceptible to leaf infection by D. bryoniae, significantly differing from the other genotypes. The lowest levels of susceptibility were identified in genotypes Perlita Busle S1, Valenciano Elíptico, Glaver, MR1, and 2526. All genotypes were susceptible to the downy mildew, albeit differing in susceptibility levels.
O crestamento gomoso do caule (Didymella bryoniae) e o míldio (Pseudoperonospora cubensis) estão entre as principais doenças do meloeiro (Cucumis melo) ocasionando redução da produtividade e da qualidade dos frutos. Apesar da importância dessas doenças, são poucos os trabalhos envolvendo a identificação de fontes de resistência a D. bryoniae e a P. cubensis no Brasil. O objetivo deste trabalho foi avaliar a resistência de genótipos comerciais de melão a essas doenças. A partir da seleção de um isolado mais agressivo, foi estudada, em condições de casa de vegetação, a resistência de 86 genótipos de meloeiro à infecção por D. bryoniae no caule. Posteriormente, em condições de campo, foi avaliada a resistência conjunta de 28 genótipos ao crestamento gomoso e ao míldio. Em casa de vegetação, todos os 86 genótipos de meloeiro avaliados foram infectados e mostraram sintomas de crestamento no caule, quatro dias após a inoculação. Houve variação significativa nos níveis de resistência entre os genótipos avaliados. No campo, sob inóculo natural, os genótipos Taslaki e Sary Juliabi mostraram-se mais suscetíveis à infecção por D. bryoniae nas folhas, diferindo significativamente dos demais genótipos. Os menores níveis de suscetibilidade foram verificados nos genótipos Perlita Busle S1, Valenciano Elíptico, Glaver, MR1 e 2526. Na avaliação da resistência ao míldio, todos os genótipos foram considerados suscetíveis, embora tenham sido encontradas diferenças nos níveis de suscetibilidade.
Moringa oleifera Lam. é uma espécie arbórea originária do noroeste indiano, cultivada graças ao seu valor alimentar, medicinal, industrial e no tratamento de água para o consumo humano. Os efeitos do ...peso de sementes e do substrato na germinação e desenvolvimento das plântulas foram determinados, sob condições de casa de vegetação (sombrite 50% com nebulização intermitente) em Fortaleza (CE), de 29/11 a 14/12/02. Os tratamentos constaram de arranjo fatorial 3x3 referente a três categorias de semente: pesadas (272,41 g/1000 sementes), médias (218,88 g/1000 sementes) e leves (177,07 g/1000 sementes); e três substratos: vermiculita; Plantmax® e uma mistura à base de solo esterilizado (S), húmus de minhoca (H) e pó de coco lavado (PC), na proporção de 2:1:1, dispostos em delineamento inteiramente casualizado com quatro repetições (24 sementes/repetição). Efetuou-se a semeadura das três classes de pesos de sementes em bandejas de isopor de 72 células contendo os substratos, avaliando-se a percentagem, velocidade e tempo médio de germinação, altura da plântula, massa seca da parte aérea e massa seca total. As sementes pesadas e médias apresentaram maior percentagem e velocidade de germinação do que as leves; as sementes pesadas proporcionaram plântulas mais vigorosas; no substrato Plantmax® e na mistura (S+H+PC) a percentagem e a velocidade de germinação foi superior à vermiculita; e as plântulas desenvolveram-se melhor no substrato Plantmax®.
To compensate the shortage of information on the influence of seed weight and substrate over the germination and seedling development of Moringa oleifera an experiment was conducted under greenhouse conditions (50% of natural light with intermittent nebulization) in Fortaleza, Ceará State, Brazil. The treatments consisted of a 3x3 factorial arrangement three seed weights: heavy (272.41 g/1000 seeds); medium (218.88 g/1000 seeds) and light (177.07 g/1000 seeds) and three substrates: vermiculite; Plantmax® and a v/v 2:1:1 mixture based on sterilized soil (S) plus earthworm humus (H) and washed powdered coconut peels (PCP), respectively disposed on an entirely randomized design with four repetitions (24 seeds/repetition). The three seed classes were sown in isopor trays with 72 cells containing the respective substrate. The percentage, rate and average time for germination; height and dry weight of total and aerial parts of the seedling were measured. Heavy and medium seeds presented a higher percentage and rate of germination than light seeds; heavy seeds yielded more vigorous seedlings; the commercial substrate Plantmax® and the mixture (S+H+PCP) allowed a higher percentage and germination rate than vermiculite; the seedlings showed a better development on the commercial substrate Plantmax®.
Moringa oleifera Lam. é uma espécie arbórea originária do noroeste indiano, cultivada graças ao seu valor alimentar, medicinal, industrial e no tratamento de água para o consumo humano. Os efeitos do ...peso de sementes e do substrato na germinação e desenvolvimento das plântulas foram determinados, sob condições de casa de vegetação (sombrite 50% com nebulização intermitente) em Fortaleza (CE), de 29/11 a 14/12/02. Os tratamentos constaram de arranjo fatorial 3x3 referente a três categorias de semente: pesadas (272,41 g/1000 sementes), médias (218,88 g/1000 sementes) e leves (177,07 g/1000 sementes); e três substratos: vermiculita; Plantmax® e uma mistura à base de solo esterilizado (S), húmus de minhoca (H) e pó de coco lavado (PC), na proporção de 2:1:1, dispostos em delineamento inteiramente casualizado com quatro repetições (24 sementes/repetição). Efetuou-se a semeadura das três classes de pesos de sementes em bandejas de isopor de 72 células contendo os substratos, avaliando-se a percentagem, velocidade e tempo médio de germinação, altura da plântula, massa seca da parte aérea e massa seca total. As sementes pesadas e médias apresentaram maior percentagem e velocidade de germinação do que as leves; as sementes pesadas proporcionaram plântulas mais vigorosas; no substrato Plantmax® e na mistura (S+H+PC) a percentagem e a velocidade de germinação foi superior à vermiculita; e as plântulas desenvolveram-se melhor no substrato Plantmax®.
To compensate the shortage of information on the influence of seed weight and substrate over the germination and seedling development of Moringa oleifera an experiment was conducted under greenhouse conditions (50% of natural light with intermittent nebulization) in Fortaleza, Ceará State, Brazil. The treatments consisted of a 3x3 factorial arrangement three seed weights: heavy (272.41 g/1000 seeds); medium (218.88 g/1000 seeds) and light (177.07 g/1000 seeds) and three substrates: vermiculite; Plantmax® and a v/v 2:1:1 mixture based on sterilized soil (S) plus earthworm humus (H) and washed powdered coconut peels (PCP), respectively disposed on an entirely randomized design with four repetitions (24 seeds/repetition). The three seed classes were sown in isopor trays with 72 cells containing the respective substrate. The percentage, rate and average time for germination; height and dry weight of total and aerial parts of the seedling were measured. Heavy and medium seeds presented a higher percentage and rate of germination than light seeds; heavy seeds yielded more vigorous seedlings; the commercial substrate Plantmax® and the mixture (S+H+PCP) allowed a higher percentage and germination rate than vermiculite; the seedlings showed a better development on the commercial substrate Plantmax®.
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