Direct numerical simulations, performed with a high-order spectral-element method, are used to study coherent structures in turbulent pipe flow at friction Reynolds numbers $Re_{\tau } = 180$ and ...$550$. The database was analysed using spectral proper orthogonal decomposition (SPOD) to identify energetically dominant coherent structures, most of which turn out to be streaks and quasi-streamwise vortices. To understand how such structures can be modelled, the linear flow responses to harmonic forcing were computed using the singular value decomposition of the resolvent operator, using the mean field as a base flow. The SPOD and resolvent analysis were calculated for several combinations of frequencies and wavenumbers, allowing the mapping out of similarities between SPOD modes and optimal responses for a wide range of relevant scales in turbulent pipe flows. In order to explore physical reasons behind the agreement between both methods, an indicator of lift-up mechanism in the resolvent analysis was introduced, activated when optimal forcing is dominated by the wall-normal and azimuthal components, and associated response corresponds to streaks of streamwise velocity. Good agreement between leading SPOD and resolvent modes is observed in a large region of parameter space. In this region, a significant gain separation is found in resolvent analysis, which may be attributed to the strong amplification associated with the lift-up mechanism, here understood as nonlinear forcing terms leading to the appearance of streamwise vortices, which in turn form high-amplitude streaks. For both Reynolds numbers, the observed concordances were generally for structures with large energy in the buffer layer. The results highlight resolvent analysis as a pertinent reduced-order model for coherent structures in wall-bounded turbulence, particularly for streamwise elongated structures corresponding to near-wall streamwise vortices and streaks.
Twenty-four studies on twenty-three distinct languages and eleven social media illustrate the steady interest in deep learning approaches for multilingual sentiment analysis of social media. We ...improve over previous reviews with wider coverage from 2017 to 2020 as well as a study focused on the underlying ideas and commonalities behind the different solutions to achieve multilingual sentiment analysis. Interesting findings of our research are (i) the shift of research interest to cross-lingual and code-switching approaches, (ii) the apparent stagnation of the less complex architectures derived from a backbone featuring an embedding layer, a feature extractor based on a single CNN or LSTM and a classifier, (iii) the lack of approaches tackling multilingual aspect-based sentiment analysis through deep learning, and, surprisingly, (iv) the lack of more complex architectures such as the transformers-based, despite results suggest the more difficult tasks requires more elaborated architectures.
•Review of applications of Deep Learning to tackle Multilingual Sentiment Analysis.•Fast-growing interest in this field, 24 related papers since 2017 to 2020.•Coverage of 23 different languages and 11 social media data or corpus.•Mixed performance, but word embeddings and CNN or LSTM as trending choices.•Embeddings>feature extractor>classifier, prevailing architecture except for aspect SA.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In spite of the decreasing differences between rural and urban areas (e.g. in their economic structures) there are still several limitations that the rural world has to deal with. In a constantly ...changing world, rural development policies are a crucial issue to respond to current and potential future challenges of rural areas. They must therefore be flexible to reinforce or discard objectives as new challenges arise, enabling the necessary adaptations in the territories. All this justifies the call for a set of indicators that allow an accurate evaluation of these policies and programmes.
This paper presents a set of demographic, economic, environmental and social welfare indicators that must be taken into account to assess rural development and related policies. Using the qualitative Delphi methodology, a group of experts analysed 88 proposed indicators, after which a set of 25 was selected based on their importance and on the consensus of the panel. The panel also estimated the weight of each of the four dimensions considered (population, social welfare, economy and environment) within an index to measure rural development. It has therefore been found that, in addition to the economy, social welfare is one of the areas that contributes most to the development of rural areas, thus contradicting “traditional” indices based solely on economic and demographic indicators. All this points to the need to evolve towards an index based on the results of this paper.
•Rural areas still face problems that need diverse, adapted and adaptable RD policies.•RD policies must be measurable to determine whether objectives are being achieved.•Delphi method was used to design a set of indicators representing the different RD dimensions.•Indicators were selected by a panel of experts with diverse roles on RD and based on consensus.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
All organisms are sensitive to the abiotic environment, and a deteriorating environment can cause extinction. However, survival in a multispecies community depends upon interactions, and some species ...may even be favored by a harsh environment that impairs others, leading to potentially surprising community transitions as environments deteriorate. Here we combine theory and laboratory microcosms to predict how simple microbial communities will change under added mortality, controlled by varying dilution. We find that in a two-species coculture, increasing mortality favors the faster grower, confirming a theoretical prediction. Furthermore, if the slower grower dominates under low mortality, the outcome can reverse as mortality increases. We find that this tradeoff between growth and competitive ability is prevalent at low dilution, causing outcomes to shift dramatically as dilution increases, and that these two-species shifts propagate to simple multispecies communities. Our results argue that a bottom-up approach can provide insight into how communities change under stress.
Starting the discussion about the framework 2021–2027, and regarding the increasing importance given to rural areas by the European Union, multifunctionality of agriculture and its positive ...externalities can be the leverage factor to a sustainable rural development. It is therefore crucial to identify the success issues in these territories where public investment can more effectively influence the private sector. Despite the existence of many indices of development, none of them is specifically designed for the evaluation of rural areas. This lack of rural development measures hampers the process of assessing the impact of public policies applied in a particular territory, or, in an ex-ante perspective, the identification of the areas where the use of public funds would be more effective. This work hence proposes the design of a Rural Development Index which would cover the defining characteristics of each region’s development. The index has been constructed based on four dimensions: population, social, economic and environmental, with each of them being composed of different indicators. The index is finally applied it to 15 municipalities in a Portuguese NUT III region (North Alentejo) using the most recent data available from the 2011 Portuguese Census. The use of the index has allowed a comparative analysis of values of each territorial unit in different years, producing some conclusions on the effectiveness of the implementation of public policies. It was also possible to identify the dimensions in which the public development policies can improve their results, and how these dimensions contribute to different development levels of the territories.
We investigate spanwise-coherent structures in the turbulent flow around airfoils, motivated by their connection with trailing-edge noise. We analyse well-resolved large-eddy simulations (LES) of the ...flow around NACA 0012 and NACA 4412 airfoils, both at a Reynolds number of 400 000 based on the chord length. Spectral proper orthogonal decomposition performed on the data reveals that the most energetic coherent structures are hydrodynamic waves, extending over the turbulent boundary layers around the airfoils with significant amplitudes near the trailing edge. Resolvent analysis was used to model such structures, using the mean field as a base flow. We then focus on evaluating the dependence of such structures on the domain size, to ensure that they are not an artefact of periodic boundary conditions in small computational boxes. To this end, we performed incompressible LES of a zero-pressure-gradient turbulent boundary layer, for three different spanwise sizes, with the momentum-thickness Reynolds number matching those near the airfoils trailing edge. The same coherent hydrodynamic waves were observed for the three domains. Such waves are accurately modelled as the most amplified flow response from resolvent analysis. The signature of such wide structures is seen in non-premultiplied spanwise wavenumber spectra, which collapse for the three computational domains. These results suggest that the spanwise-elongated structures are not domain-size dependent for the studied simulations, indicating thus the presence of very wide structures in wall-bounded turbulent flows.
OBJECTIVE: 1) To determine factors affecting adenosine deaminase (ADA) levels in pleural fluid (PF), and 2) to establish the optimal ADA cut-off level for a Brazilian population.DESIGN: ADA levels in ...PF of 309 patients were analysed to investigate pleural effusion. All patients
were evaluated for age, sex and presence of tuberculosis (TB) based on a positive pleural biopsy. Differences in ADA levels between groups were analysed using Kruskal-Wallis one-way analysis of variance. Logistic regression analysis was also carried out to predict the occurrence of TB. ADA
cut-off levels were selected using the receiver operating characteristic (ROC) curve.RESULTS: The mean PF ADA level was significantly higher in the tuberculous pleural group than in non-tuberculous pleural patients (63.3 ± 29 IU/l vs. 19 ± 31 IU/l, P < 0.001). There
was a significant correlation between PF ADA levels and age: for patients aged 45 years, the ROC curve for ADA had an area under the curve of 0.91. An ADA level of 29 IU/l resulted in a sensitivity of 88.6% and specificity of 91.5%.CONCLUSIONS: There is a significant negative correlation between PF ADA level and age. The use of a lower ADA cut-off reduces the number of false-negative results.
This paper proposes the development of an index to assess rural development based on a set of 25 demographic, economic, environmental, and social welfare indicators previously selected through a ...Delphi approach. Three widely accepted aggregation methods were then tested: a mixed arithmetic/geometric mean without weightings for each indicator; a weighted arithmetic mean using the weights previously generated by the Delphi panel and an aggregation through Principal Component Analysis.
These three methodologies were later applied to 9 Portuguese NUTS III regions using the most recent data available (2009–2020) and the results were presented to a group of experts in rural development who indicated which of the aggregation methods best measured the levels of rural development of the different territories. Finally, it was concluded that the unweighted arithmetic/geometric mean was the most accurate methodology for aggregating indicators to create a Rural Development Index.
•Development of a rural development index using indicators selected by an expert panel.•Create rural development indexes by applying different aggregation methods.•Testing the most accurate method to aggregate indicators in a rural development index.•An effective tool for both policymakers and managers of rural development programs.•A useful tool to measure the impact of cohesion policy and structural programmes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Environmental disturbances have long been theorized to play a significant role in shaping the diversity and composition of ecosystems. However, an inability to specify the characteristics of a ...disturbance experimentally has produced an inconsistent picture of diversity-disturbance relationships (DDRs). Here, using a high-throughput programmable culture system, we subjected a soil-derived bacterial community to dilution disturbance profiles with different intensities (mean dilution rates), applied either constantly or with fluctuations of different frequencies. We observed an unexpected U-shaped relationship between community diversity and disturbance intensity in the absence of fluctuations. Adding fluctuations increased community diversity and erased the U-shape. All our results are well-captured by a Monod consumer resource model, which also explains how U-shaped DDRs emerge via a novel 'niche flip' mechanism. Broadly, our combined experimental and modeling framework demonstrates how distinct features of an environmental disturbance can interact in complex ways to govern ecosystem assembly and offers strategies for reshaping the composition of microbiomes.
The effect of environmental fluctuations is a major question in ecology. While it is widely accepted that fluctuations and other types of disturbances can increase biodiversity, there are fewer ...examples of other types of outcomes in a fluctuating environment. Here we explore this question with laboratory microcosms, using cocultures of two bacterial species, P. putida and P. veronii. At low dilution rates we observe competitive exclusion of P. veronii, whereas at high dilution rates we observe competitive exclusion of P. putida. When the dilution rate alternates between high and low, we do not observe coexistence between the species, but rather alternative stable states, in which only one species survives and initial species' fractions determine the identity of the surviving species. The Lotka-Volterra model with a fluctuating mortality rate predicts that this outcome is independent of the timing of the fluctuations, and that the time-averaged mortality would also lead to alternative stable states, a prediction that we confirm experimentally. Other pairs of species can coexist in a fluctuating environment, and again consistent with the model we observe coexistence in the time-averaged dilution rate. We find a similar time-averaging result holds in a three-species community, highlighting that simple linear models can in some cases provide powerful insight into how communities will respond to environmental fluctuations.
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