197 research outputs found

    A Scalable Feature Selection and Opinion Miner Using Whale Optimization Algorithm

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    Due to the fast-growing volume of text documents and reviews in recent years, current analyzing techniques are not competent enough to meet the users' needs. Using feature selection techniques not only support to understand data better but also lead to higher speed and also accuracy. In this article, the Whale Optimization algorithm is considered and applied to the search for the optimum subset of features. As known, F-measure is a metric based on precision and recall that is very popular in comparing classifiers. For the evaluation and comparison of the experimental results, PART, random tree, random forest, and RBF network classification algorithms have been applied to the different number of features. Experimental results show that the random forest has the best accuracy on 500 features. Keywords: Feature selection, Whale Optimization algorithm, Selecting optimal, Classification algorith

    Mapping opportunities and challenges for rewilding in Europe

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    Farmland abandonment takes place across the world due to socio-economic and ecological drivers. In Europe agricultural and environmental policies aim to prevent abandonment and halt ecological succession. Ecological rewilding has been recently proposed as an alternative strategy. We developed a framework to assess opportunities for rewilding across different dimensions of wilderness in Europe. We mapped artificial light, human accessibility based on transport infrastructure, proportion of harvested primary productivity (i.e., ecosystem productivity appropriated by humans through agriculture or forestry), and deviation from potential natural vegetation in areas projected to be abandoned by 2040. At the continental level, the levels of artificial light were low and the deviation from potential natural vegetation was high in areas of abandonment. The relative importance of wilderness metrics differed regionally and was strongly connected to local environmental and socio-economic contexts. Large areas of projected abandonment were often located in or around Natura 2000 sites. Based on these results, we argue that management should be tailored to restore the aspects of wilderness that are lacking in each region. There are many remaining challenges regarding biodiversity in Europe, but megafauna species are already recovering. To further potentiate large-scale rewilding, Natura 2000 management would need to incorporate rewilding approaches. Our framework can be applied to assessing rewilding opportunities and challenges in other world regions, and our results could guide redirection of subsidies to manage social-ecological systems

    A novel class of microRNA-recognition elements that function only within open reading frames.

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    MicroRNAs (miRNAs) are well known to target 3' untranslated regions (3' UTRs) in mRNAs, thereby silencing gene expression at the post-transcriptional level. Multiple reports have also indicated the ability of miRNAs to target protein-coding sequences (CDS); however, miRNAs have been generally believed to function through similar mechanisms regardless of the locations of their sites of action. Here, we report a class of miRNA-recognition elements (MREs) that function exclusively in CDS regions. Through functional and mechanistic characterization of these 'unusual' MREs, we demonstrate that CDS-targeted miRNAs require extensive base-pairing at the 3' side rather than the 5' seed; cause gene silencing in an Argonaute-dependent but GW182-independent manner; and repress translation by inducing transient ribosome stalling instead of mRNA destabilization. These findings reveal distinct mechanisms and functional consequences of miRNAs that target CDS versus the 3' UTR and suggest that CDS-targeted miRNAs may use a translational quality-control-related mechanism to regulate translation in mammalian cells

    Disparate oxidant gene expression of airway epithelium compared to alveolar macrophages in smokers

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    <p>Abstract</p> <p>Background</p> <p>The small airway epithelium and alveolar macrophages are exposed to oxidants in cigarette smoke leading to epithelial dysfunction and macrophage activation. In this context, we asked: what is the transcriptome of oxidant-related genes in small airway epithelium and alveolar macrophages, and does their response differ substantially to inhaled cigarette smoke?</p> <p>Methods</p> <p>Using microarray analysis, with TaqMan RT-PCR confirmation, we assessed oxidant-related gene expression in small airway epithelium and alveolar macrophages from the same healthy nonsmoker and smoker individuals.</p> <p>Results</p> <p>Of 155 genes surveyed, 87 (56%) were expressed in both cell populations in nonsmokers, with higher expression in alveolar macrophages (43%) compared to airway epithelium (24%). In smokers, there were 15 genes (10%) up-regulated and 7 genes (5%) down-regulated in airway epithelium, but only 3 (2%) up-regulated and 2 (1%) down-regulated in alveolar macrophages. Pathway analysis of airway epithelium showed oxidant pathways dominated, but in alveolar macrophages immune pathways dominated.</p> <p>Conclusion</p> <p>Thus, the response of different cell-types with an identical genome exposed to the same stress of smoking is different; responses of alveolar macrophages are more subdued than those of airway epithelium. These findings are consistent with the observation that, while the small airway epithelium is vulnerable, alveolar macrophages are not "diseased" in response to smoking.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov ID: NCT00224185 and NCT00224198</p

    Effect of time of administration on cholesterol-lowering by psyllium: a randomized cross-over study in normocholesterolemic or slightly hypercholesterolemic subjects

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    BACKGROUND: Reports of the use of psyllium, largely in hypercholesterolemic men, have suggested that it lowers serum cholesterol as a result of the binding of bile acids in the intestinal lumen. Widespread advertisements have claimed an association between the use of soluble fibre from psyllium seed husk and a reduced risk of coronary heart disease. Given the purported mechanism of cholesterol-lowering by psyllium, we hypothesized that there would be a greater effect when psyllium is taken with breakfast than when taken at bedtime. Secondarily, we expected to confirm a cholesterol-lowering effect of psyllium in subjects with "average" cholesterol levels. METHODS: Sixteen men and 47 women ranging in age from 18 to 77 years [mean 53 +/- 13] with LDL cholesterol levels that were normal or slightly elevated but acceptable for subjects at low risk of coronary artery disease were recruited from general gastroenterology and low risk lipid clinics. Following a one month dietary stabilization period, they received an average daily dose of 12.7 g of psyllium hydrophilic mucilloid, in randomized order, for 8 weeks in the morning and 8 weeks in the evening. Change from baseline was determined for serum total cholesterol, LDL, HDL and triglycerides. RESULTS: Total cholesterol for the "AM first" group at baseline, 8 and 16 weeks was 5.76, 5.77 and 5.80 mmol/L and for the "PM first" group the corresponding values were 5.47, 5.61 and 5.57 mmol/L. No effect on any lipid parameter was demonstrated for the group as a whole or in any sub-group analysis. CONCLUSION: The timing of psyllium administration had no effect on cholesterol-lowering and, in fact, no cholesterol-lowering was observed. Conclusions regarding the effectiveness of psyllium for the prevention of heart disease in the population at large may be premature

    A Ribosomal Misincorporation of Lys for Arg in Human Triosephosphate Isomerase Expressed in Escherichia coli Gives Rise to Two Protein Populations

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    We previously observed that human homodimeric triosephosphate isomerase (HsTIM) expressed in Escherichia coli and purified to apparent homogeneity exhibits two significantly different thermal transitions. A detailed exploration of the phenomenon showed that the preparations contain two proteins; one has the expected theoretical mass, while the mass of the other is 28 Da lower. The two proteins were separated by size exclusion chromatography in 3 M urea. Both proteins correspond to HsTIM as shown by Tandem Mass Spectrometry (LC/ESI-MS/MS). The two proteins were present in nearly equimolar amounts under certain growth conditions. They were catalytically active, but differed in molecular mass, thermostability, susceptibility to urea and proteinase K. An analysis of the nucleotides in the human TIM gene revealed the presence of six codons that are not commonly used in E. coli. We examined if they were related to the formation of the two proteins. We found that expression of the enzyme in a strain that contains extra copies of genes that encode for tRNAs that frequently limit translation of heterologous proteins (Arg, Ile, Leu), as well as silent mutations of two consecutive rare Arg codons (positions 98 and 99), led to the exclusive production of the more stable protein. Further analysis by LC/ESI-MS/MS showed that the 28 Da mass difference is due to the substitution of a Lys for an Arg residue at position 99. Overall, our work shows that two proteins with different biochemical and biophysical properties that coexist in the same cell environment are translated from the same nucleotide sequence frame

    Calcineurin Interacts with PERK and Dephosphorylates Calnexin to Relieve ER Stress in Mammals and Frogs

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    Background: The accumulation of misfolded proteins within the endoplasmic reticulum (ER) triggers a cellular process known as the Unfolded Protein Response (UPR). One of the earliest responses is the attenuation of protein translation. Little is known about the role that Ca 2+ mobilization plays in the early UPR. Work from our group has shown that cytosolic phosphorylation of calnexin (CLNX) controls Ca 2+ uptake into the ER via the sarco-endoplasmic reticulum Ca 2+-ATPase (SERCA) 2b. Methodology/Principal Findings: Here, we demonstrate that calcineurin (CN), a Ca 2+ dependent phosphatase, associates with the (PKR)-like ER kinase (PERK), and promotes PERK auto-phosphorylation. This association, in turn, increases the phosphorylation level of eukaryotic initiation factor-2 a (eIF2-a) and attenuates protein translation. Data supporting these conclusions were obtained from co-immunoprecipitations, pull-down assays, in-vitro kinase assays, siRNA treatments and [ 35 S]-methionine incorporation measurements. The interaction of CN with PERK was facilitated at elevated cytosolic Ca 2+ concentrations and involved the cytosolic domain of PERK. CN levels were rapidly increased by ER stressors, which could be blocked by siRNA treatments for CN-Aa in cultured astrocytes. Downregulation of CN blocked subsequent ER-stress-induced increases in phosphorylated elF2-a. CN knockdown in Xenopus oocytes predisposed them to induction of apoptosis. We also found that CLNX was dephosphorylated by CN when Ca 2+ increased. These data were obtained from [c 32 P]-CLN

    Revealing the Functional Neuroanatomy of Intrinsic Alertness Using fMRI: Methodological Peculiarities

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    Clinical observations and neuroimaging data revealed a right-hemisphere fronto-parietal-thalamic-brainstem network for intrinsic alertness, and additional left fronto-parietal activity during phasic alertness. The primary objective of this fMRI study was to map the functional neuroanatomy of intrinsic alertness as precisely as possible in healthy participants, using a novel assessment paradigm already employed in clinical settings. Both the paradigm and the experimental design were optimized to specifically assess intrinsic alertness, while at the same time controlling for sensory-motor processing. The present results suggest that the processing of intrinsic alertness is accompanied by increased activity within the brainstem, thalamus, anterior cingulate gyrus, right insula, and right parietal cortex. Additionally, we found increased activation in the left hemisphere around the middle frontal gyrus (BA 9), the insula, the supplementary motor area, and the cerebellum. Our results further suggest that rather minute aspects of the experimental design may induce aspects of phasic alertness, which in turn might lead to additional brain activation in left-frontal areas not normally involved in intrinsic alertness. Accordingly, left BA 9 activation may be related to co-activation of the phasic alertness network due to the switch between rest and task conditions functioning as an external warning cue triggering the phasic alertness network. Furthermore, activation of the intrinsic alertness network during fixation blocks due to enhanced expectancy shortly before the switch to the task block might, when subtracted from the task block, lead to diminished activation in the typical right hemisphere intrinsic alertness network. Thus, we cautiously suggest that – as a methodological artifact – left frontal activations might show up due to phasic alertness involvement and intrinsic alertness activations might be weakened due to contrasting with fixation blocks, when assessing the functional neuroanatomy of intrinsic alertness with a block design in fMRI studies

    Setback distances as a conservation tool in wildlife-human interactions : testing their efficacy for birds affected by vehicles on open-coast sandy beaches

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    In some wilderness areas, wildlife encounter vehicles disrupt their behaviour and habitat use. Changing driver behaviour has been proposed where bans on vehicle use are politically unpalatable, but the efficacy of vehicle setbacks and reduced speeds remains largely untested. We characterised bird-vehicle encounters in terms of driver behaviour and the disturbance caused to birds, and tested whether spatial buffers or lower speeds reduced bird escape responses on open beaches. Focal observations showed that: i) most drivers did not create sizeable buffers between their vehicles and birds; ii) bird disturbance was frequent; and iii) predictors of probability of flushing (escape) were setback distance and vehicle type (buses flushed birds at higher rates than cars). Experiments demonstrated that substantial reductions in bird escape responses required buffers to be wide (&gt; 25 m) and vehicle speeds to be slow (&lt; 30 km h-1). Setback distances can reduce impacts on wildlife, provided that they are carefully designed and derived from empirical evidence. No speed or distance combination we tested, however, eliminated bird responses. Thus, while buffers reduce response rates, they are likely to be much less effective than vehicle-free zones (i.e. beach closures), and rely on changes to current driver behaviou
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