1,056 research outputs found
Environmental benchmarks based on ecotoxicological assessment with planktonic species might not adequately protect benthic assemblages in lotic systems
Freshwater ecosystems face widespread diffuse and point-source contamination. Species Sensitivity Distributions (SSDs) have been used as a tool to determine chemical concentration benchmarks that represent protective levels for most species in the environment. Here we used a SSD approach to assess on the adequacy of standard planktonic organisms to reflect the response of benthic communities, critically supporting the structure and function of lotic ecosystems. For the purpose, SSDs reflecting non-lethal responses of standard planktonic and selected benthic organisms were built based on EC50 values (collected in the literature or estimated following testing herein) regarding three model contaminants: potassium dichromate (PD), 3,5-dichlorophenol (DCP) and lead chloride (LC). The derived HC5 estimates were discriminatory between chemicals and the uncertainty associated with the estimate was remarkably low. The HC5 estimates with corresponding uncertainty were generally within the same order of magnitude for the three chemicals tested, with better discrimination between chemicals regarding their hazardous potential being achieved for benthic organisms: DCP was clearly less hazardous than PD, but LC tends to be as hazardous as PD and DCP (assuming the confidence interval ranges). Moreover, benthic communities were more sensitive to both DCP and PD, in this later case the HC5 being lower by more than one order of magnitude than that found for planktonic communities; for LC, confidence intervals overlapped, preventing a feasible assumption regarding differential sensitivity of the compared communities. Microphytobenthos was highlighted as the most sensitive group to the three tested chemicals in SSDs covering the benthic compartment, while SSDs with planktonic organisms did not consistently show trends in sensitivity ordering. Overall, our results suggest that protective benchmarks retrieved from SSDs built with the responses of standard planktonic organisms (which are the most commonly used for regulation purposes) do not adequately protect benthic communities.publishe
Study of the dust produced in rehabilitation works
"First International Symposium on Risk Analysis and Safety of Complex Structures and Components (IRAS 2019)"Urban rehabilitation is becoming more frequent nowadays. With cities full of falling buildings and no space to build new ones, the only solution is to rehabilitate the existing heritage in order to give new life to the vacant buildings and repopulate the cities. A large amount of the built heritage suffers from advanced degradation, making the recovery, increasing the complexity of the rehabilitation and restoration intervention and implying a highly specialized interdisciplinary component. In this type of works more dust is produced than in a new work. In addition, the origin and composition of existing materials is often unknown and can therefore pose many risks to the health of workers. Meaning, dust is breathable and can remain in the air for a long period of time, being invisible to the naked eye and very light. When a building is being demolishing, the production of dust increases significantly. Depending on the type of materials to demolish, the risk of occupational diseases, or risks, to the health of workers may be great. To avoid such risks, preventive measures must be taken in the execution of the tasks. In this study, the dust of two rehabilitation works in the district of Viana do Castelo was studied through experimental tests in order to verify the composition of the demolished materials. Particles characterization was done, using scanning electron microscopy (SEM). Then, with the tests results, the chemical composition of the existing materials was analyzed in detail. After that, the chemical components of demolished materials were carefully studied to identify which of these particles could represent a risk to the workers? health. As a conclusion the preventive measures that workers must take when performing rehabilitation works are presented, depending on what type of materials they are potentially exposed.(undefined
Post-fire diversity and abundance in pine and eucalipt stands in Portugal: effects of biogeography, topography, forest type and post-fire management
This study concerned the mid-term regeneration of the woody understory vegetation of pure and mixed
stands of Pinus pinaster Ait. and Eucalyptus globulus Labill. in northern and central Portugal following
wildfires in 2005 and 2006. Pine and eucalypt stands are the most widespread and most fire-prone forest
types in Portugal. The main aim was to investigate the importance of biogeography, topography, forest
type and post-fire management operations in explaining the patterns in shrub diversity (species richness)
and abundance (cover). To this end, 284 study sites in four distinct biogeographic regions were sampled 5
to 7 years following the last wildfire. At each site, the presence and cover of individual shrub species were
estimated using 4 sub-plot of approximately 10 m2 each. The entire data set was analyzed by means of
GLM using a total of seven explanatory variables: biogeographic region, forest type, three types post-fire
management operations (soil tillage, tree harvesting, and shrub clearance), and two topographic variables
(slope angle and elevation). The GLM analysis was also done for the individual biogeographic regions.
Biogeographic region and slope steepness were key factors explaining shrub species richness, albeit the
role of slope angle was possibly linked to the intensity of past land use.
Biogeographic region equally played a significant role in explaining the cover of all shrubs together as
well as of the shrubs of Leguminosae and Cistaceae. All three types of post-fire management operations
appeared to hamper the recovery of resprouters and Leguminosae, whereas just tree harvesting and
shrub clearance (but not soil tillage) negatively affected the cover of seeder species. These impacts of
post-fire management operations had a noticeable region-specific component, being more relevant in
the less productive biogeographic regions.
Also the role of forest type depended strongly on biogeographic region. It was only significant in the
South Mediterranean region, where pine plantations had a higher total shrub cover as well as higher covers
of seeders and Cistaceae. Possibly, however, this significant role of forest type could be due to the
lower incidence of shrub clearance in the pine standsinfo:eu-repo/semantics/publishedVersio
Reduced pancreatic β-cell mass is associated with decreased FoxO1 and Erk1/2 protein phosphorylation in low-protein malnourished rats
A low-protein diet leads to functional and structural pancreatic islet alterations, including islet hypotrophy. Insulin-signaling pathways are involved in several adaptive responses by pancreatic islets. We determined the levels of some insulin-signaling proteins related to pancreatic islet function and growth in malnourished rats. Adult male Wistar rats (N = 20 per group) were fed a 17% protein (normal-protein diet; NP) or 6% protein (low-protein diet; LP), for 8 weeks. At the end of this period, blood glucose and serum insulin and albumin levels were measured. The morphometric parameters of the endocrine pancreas and the content of some proteins in islet lysates were determined. The β-cell mass was significantly reduced (≅65%) in normoglycemic but hypoinsulinemic LP rats compared to NP rats. Associated with these alterations, a significant 30% reduction in insulin receptor substrate-1 and a 70% increase in insulin receptor substrate-2 protein content were observed in LP islets compared to NP islets. The phosphorylated serine-threonine protein kinase (pAkt)/Akt protein ratio was similar in LP and NP islets. The phosphorylated forkhead-O1 (pFoxO1)/FoxO1 protein ratio was decreased by 43% in LP islets compared to NP islets (P < 0.05). Finally, the ratio of phosphorylated-extracellular signal-related kinase 1/2 (pErk1/2) to total Erk1/2 protein levels was decreased by 71% in LP islets compared to NP islets (P < 0.05). Therefore, the reduced β-cell mass observed in LP rats is associated with the reduction of phosphorylation in mitogenic-related signals, FoxO1 and Erk proteins. The cause/effect basis of this association remains to be determined4210935941FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2/04310-4; 04/11684-9; 03/10829-
Modern relationships between microscopic charcoal in marine sediments and fire regimes on adjacent landmasses to refine the interpretation of marine paleofire records: An Iberian case study
Marine microcharcoal records provide invaluable information to understand changes in biomass burning and its drivers over multiple glacial and interglacial cycles and to evaluate fire models under warmer climates than today. However, quantitative reconstructions of burnt area, fire intensity and frequency from these records need calibration studies of the current fire-microcharcoal relationship. Here, we present the analysis of microcharcoal concentration and morphology in 102 core-top sediment samples collected in the Iberian margin and the Gulf of Cádiz. We show that microcharcoal concentrations are influenced by the water depth or the distance from the river mouth. At regional scale, the mean microcharcoal concentrations and microcharcoal elongation (length to width ratio) show a marked latitudinal variation in their distribution, primarily controlled by the type of burnt vegetation in the adjacent continent. High microcharcoal concentrations in marine sediments represent rare, large and intense fires in open Mediterranean woodlands. Based on these results, the increasing trend of microcharcoal concentrations recorded since 8 ka in the well-known marine sedimentary core MD95-2042 off the Iberian margin indicates the occurrence of large and infrequent fires of high intensity due to the progressive degradation of the Mediterranean forest and the expansion of shrublands
Beyond the limits of oxygen: effects of hypoxia in a hormone-independent prostate cancer cell line
Prostate cancer (PCa) has a high incidence worldwide. One of the major causes of PCa resistance is intratumoral hypoxia. In solid tumors, hypoxia is strongly associated with malignant progression and resistance to therapy, which is an indicator of poor prognosis. The antiproliferative effect and induced death caused by doxorubicin, epirubicin, cisplatin, and flutamide in a hormone-independent PCa cell line will be evaluated. The hypoxia effect on drug resistance to these drugs, as well as cell proliferation and migration, will be also analyzed. All drugs induced an antiproliferative effect and also cell death in the cell line under study. Hypoxia made the cells more resistant to all drugs. Moreover, our results reveal that long time cell exposure to hypoxia decreases cellular proliferation and migration. Hypoxia can influence cellular resistance, proliferation, and migration. This study shows that hypoxia may be a key factor in the regulation of PCa.info:eu-repo/semantics/publishedVersio
Multicentric Genome-Wide Association Study for Primary Spontaneous Pneumothorax
Despite elevated incidence and recurrence rates for Primary Spontaneous Pneumothorax (PSP), little is known about its etiology, and the genetics of idiopathic PSP remains unexplored. To identify genetic variants contributing to sporadic PSP risk, we conducted the first PSP genome-wide association study. Two replicate pools of 92 Portuguese PSP cases and of 129 age- and sex-matched controls were allelotyped in triplicate on the Affymetrix Human SNP Array 6.0 arrays. Markers passing quality control were ranked by relative allele score difference between cases and controls (|RASdiff|), by a novel cluster method and by a combined Z-test. 101 single nucleotide polymorphisms (SNPs) were selected using these three approaches for technical validation by individual genotyping in the discovery dataset. 87 out of 94 successfully tested SNPs were nominally associated in the discovery dataset. Replication of the 87 technically validated SNPs was then carried out in an independent replication dataset of 100 Portuguese cases and 425 controls. The intergenic rs4733649 SNP in chromosome 8 (between LINC00824 and LINC00977) was associated with PSP in the discovery (P = 4.07E-03, ORC[95% CI] = 1.88[1.22-2.89]), replication (P = 1.50E-02, ORC[95% CI] = 1.50[1.08-2.09]) and combined datasets (P = 8.61E-05, ORC[95% CI] = 1.65[1.29-2.13]). This study identified for the first time one genetic risk factor for sporadic PSP, but future studies are warranted to further confirm this finding in other populations and uncover its functional role in PSP pathogenesis
First observation of the Λ b 0 → D + D − Λ decay
The Λb0 → D+D−Λ decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.3 fb−1. Using the B0 → D+D−KS0 decay as a reference channel, the product of the relative production cross-section and decay branching fractions is measured to beR=σΛb0σB0=BΛb0→D+D−ΛBB0→D+D−KS0=0.179±0.022±0.014, where the first uncertainty is statistical and the second is systematic. The known branching fraction of the reference channel, BB0→D+D−KS0, and the cross-section ratio, σΛb0/σB0, previously measured by LHCb are used to derive the branching fraction of the Λb0→ D+D−Λ decayBΛb0→D+D−Λ=1.24±0.15±0.10±0.28±0.11×10−4, where the third and fourth contributions are due to uncertainties of BB0→D+D−KS0 and σΛb0/σB0, respectively. Inspection of the D+Λ and D+D− invariant-mass distributions suggests a rich presence of intermediate resonances in the decay. The Λb0 → D*+D−Λ decay is also observed for the first time as a partially reconstructed component in the D+D−Λ invariant mass spectrum
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