1,028 research outputs found
Bioclimatic modelling in the holocene and in future warming scenarios in Arbutus unedo L.
Growing forests wildfires in Portugal are an increasing concern since forests in the Mediterranean region are vulnerable to recent global warming. Long-term negative effects are expected on the vegetation with the coming increasing drought. The strawberry tree (Arbutus unedo L.) displays potential to be a successfully business-like cultured in several regions of Portugal and southern Europe, as it is well adapted to climate and soils. In Portugal, this species has been used by local populations particularly for spirit production and for fruit consumption, although it has different possible commercial uses, from processed and fresh fruit production to ornamental, pharmaceutical and chemical applications. In addition, due to its pioneer status, it is valuable for land recovery and desertification avoidance, besides being fire resistant. The available strawberry tree’s data is presence-only. For modelling purposes, a set of placements within the landscape of interest (Portugal) was applied. The species, observed in 318 plots, together with a vector of environmental covariates (7 bioclimatic attributes, slope and altitude) and a defined background were used for modeling purposes. Maxent 3.4.1 was the used software, where the estimated quantity is the probability of the presence of the species, conditioned on the environment. Maxent uses the environmental covariate data from the occurrence records and the background sample, to estimate the ratio between the conditional density of the covariates at the presence sites and the marginal (i.e., unconditional) density of covariates across the study area and so, estimating the relative suitability of one place vs. another. Three different climate scenarios (control run; 2050 and 2070) were tested for two emission scenarios (RCP 4.5 and RCP 8.5, WorldClim), besides the past, 6,000 BP (Mid-Holocene). The reduction of habitat suitable for this species is very significant in the southern regions, even for the best warming scenario (RCP 4.5) in 2050. Central and Northern mountain regions are predicted refuge for this species. Forest policies and management should consider the impact of climate change on the usable areas for forestry, seeing a case-study species particularly adapted to the Mediterranean regions and wildfires, such as strawberry tree. The distribution of the species in the Middle Holocene agrees with previous genetic and fossils studies in the region, which supported two putative refuges for the species since the Last Glacial Maximum and a cryptic refugia in the East-Central mountain region.info:eu-repo/semantics/publishedVersio
Sensitive optical detection of clinically relevant biomarkers in affordable microfluidic devices: Overcoming substrate diffusion limitations
One of the biggest challenges in miniaturization of optical immunoassays is the short light path distance of microchannels/microcapillaries. Protein biomarkers are often presented in circulating blood in the picomolar-femtomolar range, requiring exceptional levels of sensitivity that cannot be met with traditional chromogenic substrates and without sophisticated, bulky detection systems. This study discloses an effective strategy for increasing the sensitivity and shorten the total test time for sandwich ELISAs in microfluidic devices optically interrogated, based on enhancing enzymatic amplification. We found that activity of Horseradish Peroxidase (HRP) in mesofluidic systems is highly limited by diffusion, therefore increasing the concentration of enzymatic substrate in these systems does not translate into an enhancement in enzymatic conversation. The opposite happens in microfluidic systems due to short diffusion distances, however increased concentration of the second enzymatic substrate, hydrogen peroxide (H 2O 2), leads to enzyme inhibition as herein reported. Consequently, we found that the molar ratio of o-phenylenediamine (OPD) to hydrogen peroxide from commercially substrate formulations is not suitable for miniaturized systems. Sandwich ELISA quantitation of a cancer biomarker PSA and human cytokine IL-1β in fluoropolymer microfluidic strips revealed over one order of magnitude increase in sensitivity and 10-fold decrease in incubation time by simply changing the molar ratio of OPD:H 2O 2 from 1:3 to 1:1 and increasing OPD concentration from 1 to 4 mg/ml. This enhancement in enzymatic amplification offers finally the sensitivity required for optical interrogation of novel portable and affordable microfluidic devices with inexpensive and ubiquitous smartphones and flatbed scanners. </p
The pulsating DA white dwarf star EC 14012-1446: results from four epochs of time-resolved photometry
The pulsating DA white dwarfs are the coolest degenerate stars that undergo
self-driven oscillations. Understanding their interior structure will help to
understand the previous evolution of the star. To this end, we report the
analysis of more than 200 h of time-resolved CCD photometry of the pulsating DA
white dwarf star EC 14012-1446 acquired during four observing epochs in three
different years, including a coordinated three-site campaign. A total of 19
independent frequencies in the star's light variations together with 148
combination signals up to fifth order could be detected. We are unable to
obtain the period spacing of the normal modes and therefore a mass estimate of
the star, but we infer a fairly short rotation period of 0.61 +/- 0.03 d,
assuming the rotationally split modes are l=1. The pulsation modes of the star
undergo amplitude and frequency variations, in the sense that modes with higher
radial overtone show more pronounced variability and that amplitude changes are
always accompanied by frequency variations. Most of the second-order
combination frequencies detected have amplitudes that are a function of their
parent mode amplitudes, but we found a few cases of possible resonantly excited
modes. We point out the complications in the analysis and interpretation of
data sets of pulsating white dwarfs that are affected by combination
frequencies of the form f_A+f_B-f_C intruding into the frequency range of the
independent modes.Comment: 14 pages, 6 figures, 6 tables. MNRAS, in pres
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A Lab-in-a-briefcase for rapid prostate specific antigen (PSA) screening from whole blood
We present a new concept for rapid and fully portable Prostate Specific Antigen (PSA) measurement, termed “Lab-in-a-Briefcase”, which integrates an affordable microfluidic ELISA platform utilising a melt-extruded fluoropolymer Micro Capillary Film (MCF) containing 10 bore, 200 μm internal diameter capillaries, a disposable multi-syringe aspirator (MSA) plus a sample tray pre-loaded with all required immunoassay reagents, and a portable film scanner for colorimetric signal digital quantitation. Each MSA can perform 10 replicate microfluidic immunoassays on 8 samples, allowing 80measurements to be made in less than 15 minutes based on semi-automated operation and norequirement of additional fluid handling equipment. An assay was optimised for measurement of a clinically relevant range of PSA from 0.9 to 60.0 ng/ml in 15 minutes with CVs in the order of 5% based on intra-assay variability when read using a consumer flatbed film scanner. The PSA assay performance in the MSA remained robust in the presence of undiluted or 1:2 diluted human serum or whole blood, and the matrix effect could simply be overcome by extending sample incubation times. The PSA "Lab-in-a-briefcase" is particularly suited to a low-resource health setting where diagnostic labs and automated immunoassay systems are not accessible, by allowing PSA measurement outside the laboratory using affordable equipment
Environmental risk assessment in a contaminated estuary: an integrated weight of evidence approach as a decision support tool
Environmental risk assessment of complex ecosystems such as estuaries is a challenge, where innovative
and integrated approaches are needed. The present work aimed at developing an innovative integrative
methodology to evaluate in an impacted estuary (the Sado, in Portugal, was taken as case study), the
adverse effects onto both ecosystem and human health. For the purpose, new standardized lines of
evidence based on multiple quantitative data were integrated into a weight of evidence according to a
best expert judgment approach. The best professional judgment for a weight of evidence approach in the
present study was based on the following lines of evidence: i) human contamination pathways; ii)
human health effects: chronic disease; iii) human health effects: reproductive health; iv) human health
effects: health care; v) human exposure through consumption of local agriculture produce; vi) exposure
to contaminated of water wells and agriculture soils; vii) contamination of the estuarine sedimentary
environment (metal and organic contaminants); viii) effects on benthic organisms with commercial
value; and ix) genotoxic potential of sediments. Each line of evidence was then ordinally ranked by levels
of ecological or human health risk, according to a tabular decision matrix and expert judgment. Fifteen
experts scored two fishing areas of the Sado estuary and a control estuarine area, in a scale of increasing
environmental risk and management actions to be taken. The integrated assessment allowed concluding
that the estuary should not be regarded as impacted by a specific toxicant, such as metals and organic
compounds hitherto measured, but by the cumulative risk of a complex mixture of contaminants. The
proven adverse effects on species with commercial value may be used to witness the environmental
quality of the estuarine ecosystem. This method argues in favor of expert judgment and qualitative
assessment as a decision support tool to the integrative management of estuaries. Namely it allows
communicating environmental risk and proposing mitigation measures to local authorities and population
under a holistic perspective as an alternative to narrow single line of evidence approaches, which
is mandatory to understand cause and effect relationships in complex areas like estuaries.info:eu-repo/semantics/publishedVersio
Daily oxygen consumption rhythms of Senegalese sole solea senegalensis (Kaup, 1858) juveniles
Senegalese sole is known to be a species with pronounced nocturnal feeding behaviour. However, as for most fish species, there is a lack of knowledge concerning the influence of such biological rhythmon metabolic rate.
The aim of this study was to determine whether individual variation in routine and fed metabolic rate was affected by daily light–dark rhythms in juveniles of Senegalese sole. The individual oxygen consumption measurements in Senegalese sole juveniles were determined by flow-through respirometry, at fasted conditions and after the fish were fed a single meal, the meal time started at 0930 h and fish fed ad libitum for 30 min. The measurements were made during 22 h, of which 8 h was in the light and 14 h in the dark, and started immediately after transfer to the respiratory chambers at 1100 h. The results suggest an influence of light–dark cycles in routine metabolism. It was observed that oxygen consumption increased during the dark
phase in fasted fish (FAST) but was higher during the light phase in fed fish (FEED). However, when feed is provided during the light phase, juveniles are capable of shifting oxygen consumption rhythms to respond to the energetic demands of digestion and growth. These results suggest that routine metabolism varies according to the species natural habits as Senegalese sole is known to be nocturnal. The findings of this study underline the importance of understanding the biological rhythms of the species under study before metabolic data are interpreted
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An Overview of the Use of Neural Networks for Data Mining Tasks
In the recent years the area of data mining has experienced a considerable demand for technologies that extract knowledge from large and complex data sources. There is a substantial commercial interest as well as research investigations in the area that aim to develop new and improved approaches for extracting information, relationships, and patterns from datasets. Artificial Neural Networks (NN) are popular biologically inspired intelligent methodologies, whose classification, prediction and pattern recognition capabilities have been utilised successfully in many areas, including science, engineering, medicine, business, banking, telecommunication, and many other fields. This paper highlights from a data mining perspective the implementation of NN, using supervised and unsupervised learning, for pattern recognition, classification, prediction and cluster analysis, and focuses the discussion on their usage in bioinformatics and financial data analysis tasks
Behavioural stress responses predict environmental perception in European sea bass (Dicentrarchus labrax)
Individual variation in the response to environmental challenges depends partly on innate reaction norms, partly on experience-based cognitive/emotional evaluations that individuals make of the situation. The goal of this study was to investigate whether pre-existing differences in behaviour predict the outcome of such assessment of environmental cues, using a conditioned place preference/avoidance (CPP/CPA) paradigm. A comparative vertebrate model (European sea bass, Dicentrarchus labrax) was used, and ninety juvenile individuals were initially screened for behavioural reactivity using a net restraining test. Thereafter each individual was tested in a choice tank using net chasing as aversive stimulus or exposure to familiar conspecifics as appetitive stimulus in the preferred or non preferred side respectively (called hereafter stimulation side). Locomotor behaviour (i.e. time spent, distance travelled and swimming speed in each tank side) of each individual was recorded and analysed with video software. The results showed that fish which were previously exposed to appetitive stimulus increased significantly the time spent on the stimulation side, while aversive stimulus led to a strong decrease in time spent on the stimulation side. Moreover, this study showed clearly that proactive fish were characterised by a stronger preference for the social stimulus and when placed in a putative aversive environment showed a lower physiological stress responses than reactive fish. In conclusion, this study showed for the first time in sea bass, that the CPP/CPA paradigm can be used to assess the valence (positive vs. negative) that fish attribute to different stimuli and that individual behavioural traits is predictive of how stimuli are perceived and thus of the magnitude of preference or avoidance behaviour.European Commission [265957]; Portuguese Fundacao para a Ciencia e Tecnologia (FCT) [FRH/BPD/72952/2010]; FCT [SFRH/BD/80029/2011
Valorization of plant extracts by encapsulation in lipid nanosystems for application as potential insecticides
Plants have been used for centuries to treat diseases and are considered an important source of new antimicrobial agents. Plant extracts can be obtained and their composition determined, being widely employed in the pharmaceutical and cosmetic industries. A less explored and potential application is the use as green insecticides/insect repellents, as an alternative to current pesticides. Despite the desirable properties, many of the isolated components (phytochemicals) present limitations on their use, due to high volatility and easy degradation when exposed to air. Nanoencapsulation techniques arise as promising strategies to allow the preservation and controlled release of plant extracts.
In this work, a series of plant materials, Tamus communis L., Tagetes patula L. and Ruta graveolens L., were subjected to Soxhlet extraction using various solvents and times of extraction. The extracts obtained were submitted to biological studies, to assess their potential against the insect cell line Sf9. Encapsulation assays in lipid nanosystems were carried out, with encapsulation efficiencies higher than 70%.This research was funded by Foundation for Science and Technology (FCT) for financial support to the
research centres CQ/UM (UID/QUI/00686/2016 and UID/QUI/00686/2019) and CF-UM-UP (UID/FIS/04650/2019). Funding by FCT, COMPETE2020 and FEDER through project PTDC/ASP-AGR/30154/2017 (POCI-01-0145-FEDER-030154) is also acknowledged. The NMR spectrometer Bruker Avance III 400 (part of the National NMR Network) was financed by FCT and FEDER
DODAB/Monoolein mixed cationic liposomes for gene delivery : investigation by DLS, DSC, fluorescence spectroscopy and phase scanning microscopy
FCT and FEDER for financial support to CFUM and also by funding through project PTDC/QUI/69795/2006 and PhD grant of J.P.N. Silva (SFRH/BD/46968/2009)
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