1,475 research outputs found

    Light inhibition of nitrification in sea-surface films

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    Nitrifying bacteria (ammonia- and nitrite-oxidizers) were isolated from sea-surface films collected in the Gulf of California. Laboratory studies indicate substrate oxidation by these isolates is inhibited by light. Ammonia-oxidizers showed lower nitrifying activity and a longer lag time when held in an 8-hr light:16-hr dark regime compared to those held completely in the dark, and nitrite-oxidizers showed nitrifying activity only when held in the dark. Tracer studies using 15N-ammonia corroborate that little or no nitrification occurs in the surface films of subtropical seas

    cynara cardunculus and coffee grounds as promising biodiesel sources for internal combustion compression ignition engines

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    Abstract In this study, the effect of using two innovative biodiesels - derived respectively from coffee grounds and Cynara cardunculus - in blend with neat diesel fuel, on combustion and emissions in a compression ignition engine has been investigated. During tests, load and exhaust gas recirculation were varied and results compared with those obtained with neat diesel fuel and its blends with Brassica carinata or waste cooking oil derived biodiesels. Results show a reduction or a comparable NOx and CO emission levels using Cynara cardunculus and coffee ground compared to the other fuels tested, while PM and THC emissions are penalized. Fuel consumption, as expected, is slightly reduced. EGR reduces NOx levels, while CO, THC and PM are generally penalized

    Has Xylella fastidiosa "chosen" olive trees to establish in the Mediterranean basin?

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    <p>Severe decline of olive trees was observed in the Lecce province, Apulia (Italy), and received the name ‘complesso del disseccamento rapido dell’olivo’ (olive rapid decline complex). Affected plants showed leaf scorch symptoms and dieback of twigs, branches and even of the whole plant. Similar symptoms, unusual for the area, have also been observed in other Apulian localities (Cerignola, Foggia, Canosa di Puglia, and Andria). Three fungal species were associated with the symptoms: Phaeoacremonium aleophilum, Neofusicoccum parvum, and Pleurostomophora richardsiae. The latter is the first report of this fungal species infecting olives. In the Lecce province, the bacterium Xylella fastidiosa also was detected from affected olive trees. Xylella fastidiosa is a quarantine agent in Europe that had been previously reported in the Mediterranean region, but did not spread probably because of the lack of a vector. Present findings suggest that this fundamental condition has now been met.</p

    From Marx to Gramsci to us: Laboratory to prison, and back

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    Marx and Gramsci remain two of the most constant presences and inspirations for those on the left. Yet there is a persistent sense that we have still to get them right. Perhaps this indicates that sources like this are now fully classics, to be returned, and returned to. In the case of Marx and Gramsci, a series of major works published in the Brill Historical Materialism series breaks new ground as well as returning to older controversies, both resolved and unresolved. Apart from remaining arguments concerning the status of materials unpublished in their own lifetimes, the major tension that emerges here is that between the task of immanent, contextual philology and the challenge of reading ‘Marx for today’ or ‘Gramsci for today’. The tension between text and context, and the question of what travels, conceptually persists

    Self-Supervised Learning Across Domains

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    Human adaptability relies crucially on learning and merging knowledge from both supervised and unsupervised tasks: the parents point out few important concepts, but then the children fill in the gaps on their own. This is particularly effective, because supervised learning can never be exhaustive and thus learning autonomously allows to discover invariances and regularities that help to generalize. In this paper we propose to apply a similar approach to the problem of object recognition across domains: our model learns the semantic labels in a supervised fashion, and broadens its understanding of the data by learning from self-supervised signals on the same images. This secondary task helps the network to focus on object shapes, learning concepts like spatial orientation and part correlation, while acting as a regularizer for the classification task over multiple visual domains. Extensive experiments confirm our intuition and show that our multi-task method combining supervised and self-supervised knowledge shows competitive results with respect to more complex domain generalization and adaptation solutions. It also proves its potential in the novel and challenging predictive and partial domain adaptation scenarios

    Air/methane mixture ignition with Multi-Walled Carbon Nanotubes (MWCNTs) and comparison with spark ignition

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    The possibility to ignite the single wall carbon nanotubes (SWCNTs) containing impurities of iron in atmosphere once exposed to the radiation of a flash camera was observed for the first time in 2002. Afterwards, it was proposed to exploit this property in order to use nanostructured materials as ignition agents for fuel mixtures. Finally, in 2011 it was shown that SWCNTs can be effectively used as ignition source for an air/ethylene mixture filling a constant volume combustion chamber; the observed combustion presented the characteristics of a homogeneous-like combustion. In this paper a system for the ignition of an air/methane mixture is proposed, based on the exposition of multi wall carbon nanotubes (MWCNTs) to a low consumption flash camera. Namely, several experiments have been run in which 20 mg of MWCNTs, containing 75% in weight of ferrocene, have been added to an air/methane fuel mixture inside a constant volume combustion chamber. The mixture has been heated up to 373 K and the onset pressure was set equal to 3 bar. The experiments have been run varying the equivalence ratio in the range 1–2. The combustion process so realized has been compared to that obtained igniting the mixture with a traditional spark as in spark ignition engines. The comparison has been based on chamber pressure measurement as well as combustion process images, both sampled at a frequency equal to 2,5 kHz for an overall duration of 1.8 s. Results confirm that the ignition triggered with MWCNTs leads to a homogeneous-like combustion, without observing a well-defined flame front propagation. The contrary is observed, as expected, with the spark assisted ignition. Moreover, dynamic pressure measurements show that, compared to spark assisted ignition, the MWCNTs photo-ignition determines a more rapid pressure gradient and a higher peak pressure which corresponds to a higher energy release rate

    HPLC-HRMS Global Metabolomics Approach for the Diagnosis of “Olive Quick Decline Syndrome” Markers in Olive Trees Leaves

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    Olive quick decline syndrome (OQDS) is a multifactorial disease affecting olive plants. The onset of this economically devastating disease has been associated with a Gram-negative plant pathogen called Xylella fastidiosa (Xf). Liquid chromatography separation coupled to high-resolution mass spectrometry detection is one the most widely applied technologies in metabolomics, as it provides a blend of rapid, sensitive, and selective qualitative and quantitative analyses with the ability to identify metabolites. The purpose of this work is the development of a global metabolomics mass spectrometry assay able to identify OQDS molecular markers that could discriminate between healthy (HP) and infected (OP) olive tree leaves. Results obtained via multivariate analysis through an HPLC-ESI HRMS platform (LTQ-Orbitrap from Thermo Scientific) show a clear separation between HP and OP samples. Among the differentially expressed metabolites, 18 different organic compounds highly expressed in the OP group were annotated; results obtained by this metabolomic approach could be used as a fast and reliable method for the biochemical characterization of OQDS and to develop targeted MS approaches for OQDS detection by foliage analysis

    Exploring Relationships between Demersal Resources and Environmental Factors in the Ionian Sea (Central Mediterranean)

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    The relationships between the abundance of demersal resources, environmental variables, and fishing pressure in the north-western Ionian Sea in the last two decades were evaluated. Data on the density collected during seventeen trawl surveys carried out from 1985 to 2005 were used. The following species were considered:Aristaeomorpha foliacea, Nephrops norvegicus,andParapenaeus longirostrisfor crustaceans;Merluccius merluccius, Phycis blennoides,andMullus barbatusfor teleost fish. The recruitment index was also considered forN. norvegicus, P. longirostris, M. merlucciusandMullus barbatus. Six candidate models were evaluated for each density and recruitment data set either combining fishing effort with global (NAO) and regional (SST and precipitation) climatic indices, or models separately involving fishing effort, NAO, or regional climatic indices as the only predictive variable. Model selection was carried out using an information-theoretical approach that applies Akaike's Information Criterion (AIC). High changes over time were observed for the density data and recruitment indices in each species. Apart from hake abundance and recruitment data, for which a clear positive relationship with the NAO index alone was detected, the changes observed in the other species seem to be the consequence of the interaction between bottom-up effects linked to changes in physical environment and top-down ones due to the fishing pressure
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