2,599 research outputs found

    Impacts of species misidentification on species distribution modeling with presence-only data

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    Spatial records of species are commonly misidentified, which can change the predicted distribution of a species obtained from a species distribution model (SDM). Experiments were undertaken to predict the distribution of real and simulated species using MaxEnt and presence-only data “contaminated” with varying rates of misidentification error. Additionally, the difference between the niche of the target and contaminating species was varied. The results show that species misidentification errors may act to contract or expand the predicted distribution of a species while shifting the predicted distribution towards that of the contaminating species. Furthermore the magnitude of the effects was positively related to the ecological distance between the species’ niches and the size of the error rates. Critically, the magnitude of the effects was substantial even when using small error rates, smaller than common average rates reported in the literature, which may go unnoticed while using a standard evaluation method, such as the area under the receiver operating characteristic curve. Finally, the effects outlined were shown to impact negatively on practical applications that use SDMs to identify priority areas, commonly selected for various purposes such as management. The results highlight that species misidentification should not be neglected in species distribution modeling

    Impacts of species misidentification on species distribution modeling with presence-only data

    Get PDF
    Spatial records of species are commonly misidentified, which can change the predicted distribution of a species obtained from a species distribution model (SDM). Experiments were undertaken to predict the distribution of real and simulated species using MaxEnt and presence-only data “contaminated” with varying rates of misidentification error. Additionally, the difference between the niche of the target and contaminating species was varied. The results show that species misidentification errors may act to contract or expand the predicted distribution of a species while shifting the predicted distribution towards that of the contaminating species. Furthermore the magnitude of the effects was positively related to the ecological distance between the species’ niches and the size of the error rates. Critically, the magnitude of the effects was substantial even when using small error rates, smaller than common average rates reported in the literature, which may go unnoticed while using a standard evaluation method, such as the area under the receiver operating characteristic curve. Finally, the effects outlined were shown to impact negatively on practical applications that use SDMs to identify priority areas, commonly selected for various purposes such as management. The results highlight that species misidentification should not be neglected in species distribution modeling

    Keratin peptides from chicken feathers for biomedical applications

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    Book of Abstracts of CEB Annual Meeting 2017info:eu-repo/semantics/publishedVersio

    Extending the limits of wireless power transfer to miniaturized implantable electronic devices

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    Implantable electronic devices have been evolving at an astonishing pace, due to the development of fabrication techniques and consequent miniaturization, and a higher efficiency of sensors, actuators, processors and packaging. Implantable devices, with sensing, communication, actuation, and wireless power are of high demand, as they pave the way for new applications and therapies. Long-term and reliable powering of such devices has been a challenge since they were first introduced. This paper presents a review of representative state of the art implantable electronic devices, with wireless power capabilities, ranging from inductive coupling to ultrasounds. The different power transmission mechanisms are compared, to show that, without new methodologies, the power that can be safely transmitted to an implant is reaching its limit. Consequently, a new approach, capable of multiplying the available power inside a brain phantom for the same specific absorption rate (SAR) value, is proposed. In this paper, a setup was implemented to quadruple the power available in the implant, without breaking the SAR limits. A brain phantom was used for concept verification, with both simulation and measurement data.This work is supported by FCT with the reference project PTDC/EEI-TEL/5250/2014, by FEDER funds through Projecto 3599-Promover a Produção Científica e Desenvolvimento Tecnológico e a Constituição de Redes Temáticas (3599-PPCDT) and by grant SFRH/BD/116554/2016.info:eu-repo/semantics/publishedVersio

    Stationary roller versus velodrome for maximal cycling test: a comparison

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    The present study aimed to compare the acute cardio-respiratory responses of elite cyclists to a maximal progressive exercise carried out in two different conditions: in a laboratory (using a braked roller) and in an uncovered velodrome. In both testing conditions, ten elite male cyclists (age, 22.3 ± 3.9 years) performed a maximal discontinuous progressive test of 6 minutes per level with 150 W of initial load and increasing 50 W at each level until exhaustion. The heart rate and the ventilation parameters were measured breath-by-breath using a portable metabolic cart gas analysis system with telemetry data transmission. In the first 4 levels of effort, no significant differences were found between the two test conditions regarding VO2, (p=0.193), heart rate (p=0.973) and pedaling cadence (p=0.116). Comparing the maximum values achieved by each athlete in both exercise conditions, significant differences were found for heart rate (p=0.008) and pedaling cadence (p=0.005) but not for VO2max and peak power. Each variable showed a strong correlation between both assessments (VO2, r=0.984, p=0,000; heart rate, r=0.944, p=0.005; pedaling cadence, r=0.900, p=0.014). The amount of variability explained by the linear regression model for both cardio-respiratory parameters also showed a good fit value close to one (VO2max, r2=0.968; heart rate, r2=0.892). Our results suggest that identical cycling protocols conducted in different testing conditions with the same bike leads to equivalent performance but significantly different pedaling cadence and heart rate responses

    Occlusion technique in swimming: a training method to improve exchange block time in swimming relays

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    Swimming relay events have the concern regarding a good start is shared between the incoming and outgoing swimmers. The aim of this study was to evaluate changes in exchange block time (eBT) for swimming relay events as a result of a four-week training program using the occlusion technique. MeThodS: Twenty-eight national swimmers, 12 males (age: 17±1.83 years) and 16 females (age: 19.94±5.65 years) participated in this study. Subjects were required to undergo a training program on visual perception in relay swimming over the course of four weeks; they watched videos corresponding to the last movements of a swimmer during a 4×100m freestyle relay event. The videos were presented with temporal occlusion corresponding to predetermined approaching distances (7.5 m, 5.0 m, and 2.5 m). Swimmers were required to simulate a typical position for exiting the block and to estimate the time-to-contact of the incoming swimmer. The eBT was collected during a real 4×100-m freestyle competition before and after the application of the training program. RESULTS: Female swimmers showed a decreased in EBT, with an improvement of 1.42%, despite there not being a signifcant difference (p=0.68). The male swimmers had a higher improvement in eBT after the training, with a decrease of 13.34% (p=0.68). coNcluSioNS: Visual perception practice using video occlusion techniques seems to have a positive effect. on eBT in swimming relay events, particularly in female swimmersinfo:eu-repo/semantics/publishedVersio

    The relative age effect among elite youth competitive swimmers

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    The aim of this study was to analyse the relative age effect (RAE) in competitive swimming. The best 50 Portuguese swimmers (12- to 18-year-olds) for the main individual swimming pool events of both genders were considered. Analysis was conducted on 7813 swimming event participants, taking account of respective swimmer birth dates and the Fédération Internationale de Natation points gained. Differences in the distribution of birth dates by quarter year were determined using the Chi-square. A one-way analysis of variance ANOVA was used to test for differences measured in points between individuals by quarterly birth year intervals. A two-way analysis of variance ANOVA was also conducted to test the interaction between gender and seasonal birth date with regard to performance. The results show an inequitable distribution (p<0.01) of birth dates by quarter for almost all age groups and both genders. However, the distribution of birth dates by quarter for each considered swim event shows that RAE seems to exist only for 12-year-old females and 12- to 15-year-old males. Analysing mean swimming performance, post-hoc results (p<0.01) show no consistency in RAE. Higher performance occurs among older swimmers only in 100 m butterfly (female 1998, 1st≠2nd quarter, p=0.003). The results also show no interaction between gender and seasonal birth date (p<0.01). Findings of this study show that a higher number of swimmers, particular males, are born in the first two quarters of the year, although there is mostly no effect of seasonal birth date on performance differences within the top 50 swimmers.info:eu-repo/semantics/publishedVersio

    Frequency-spectra-based high coding capacity chipless RFID using an UWB-IR approach

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    A novel methodology is proposed to reliably predict the resonant characteristics of a multipatch backscatter-based radio frequency identification (RFID) chipless tag. An ultra-wideband impulsion radio (UWB-IR)-based reader interrogates the chipless tag with a UWB pulse, and analyzes the obtained backscatter in the time domain. The RFID system consists of a radar cross-section (RCS)-based chipless tag containing a square microstrip patch antenna array in which the chipless tag is interrogated with a UWB pulse by an UWB-IR-based reader. The main components of the backscattered signal, the structural mode, and the antenna mode were identified and their spectral quality was evaluated. The study revealed that the antenna-mode backscatter includes signal carrying information, while the structural mode backscatter does not include any tag information. The simulation findings were confirmed by experimental measurements obtained in an anechoic chamber environment using a 6-bit multipatch chipless RFID tag. Finally, the novel technique does not use calibration tags and can freely orient tags with respect to the reader.This research work was supported by FCT through grant SFRH/BD/116554/2016 and by the Center for Microelectromechanical Systems Research CMEMS-UMinho

    Utilization of waste materials to improve asphalt mixtures performance

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    This study aims to develop an innovative bitumen with large quantities of waste materials to improve asphalt mixtures performance. Different amounts of waste motor oil and waste HDPE were added to a new bitumen. The bitumen modified with 10% of waste motor oil and 5% of HDPE showed promising characteristics (high softening point temperatures and penetration slightly higher than the conventional bitumen). After the selection of the most promising modified bitumen, three asphalt mixtures were produced with different bitumens (namely conventional bitumen, commercial modified bitumen and the selected modified bitumen). Beyond that, this modified bitumen improved some mechanical characteristics of the asphalt mixture where it was used, in comparison to conventional and modified asphalt mixtures.Portuguese Government and EU/FSE within a PhD fellowship (SFRH/BD98379/2013) of the FCT, in the scope of POPH/QREN, by FEDER through the Competitiveness Factors Operational Programme (COMPETE) and by national funds through the Portuguese Foundation for Science and Technology (FCT) in the scope of PLASTIROAD Project (PTDC/ECM/119179/2010

    Valorização de resíduos plásticos na modificação de betumes para pavimentos rodoviários

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    Com o aumento do tráfego rodoviário são colocadas maiores exigências aos pavimentos, surgindo a necessidade de melhorar o seu desempenho. Um método que pode melhorar significativamente a qualidade dos pavimentos flexíveis é a adição de polímeros aos ligantes/misturas betuminosas. Assim, foram produzidos ligantes modificados com polímeros reciclados, em diferentes condições, cujo desempenho foi comparado com o de ligantes convencionais e de um ligante modificado comercial. Os resultados dos ensaios laboratoriais serão utilizados na seleção de resíduos plásticos e das condições de produção do betume modificado para otimizar o seu comportamento, salientando-se que este estudo procura promover a reutilização de resíduos de uma forma mais ecológica e económica.Financiado por Fundos FEDER através do Programa Operacional Fatores de Competitividade – COMPETE e por Fundos Nacionais através da FCT – Fundação para a Ciência e a Tecnologia no âmbito do projeto PLASTIROADS (PTDC/ECM/119179/2010) e do projeto estratégico UI 4047 – 2011-2012
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