216 research outputs found
Mixed-effects generalized height-diameter model: a tool for forestry management of young sweet chestnut stands
Height is a key variable for forest management. However, tree height measurements are expensive and timeconsuming,
requiring more effort to measure in the forest than diameter breast height measurements. Indeed,
height-diameter (h-d) models are increasingly used to overcome the difficulty in measuring tree heights.
Therefore, more accurate h-d models are increasingly needed. The mixed-effects modeling approach is a mainstream
method to estimate h-d models. This technique was used to model the h-d relationship in the first 24 years
of growth of sweet chestnut (Castanea sativa Mill.) high-forest stands for timber production. A dataset of 10,868
h-d observations and 57 plots of local-inventory data were considered individually. Simple mixed-effects models
considering a grouping structure in the data (plot-level) were obtained, and generalized mixed-effects models
were developed by expanding the fixed structure of simple mixed-effects models with stand-level variables.
Several alternative model forms were tested in terms of accuracy, applicability and measurement effort. Different
alternatives for calibrated predictions of tree height at plot level were analyzed, and considerations on the tradeoff
between easy-to-use equations in the field practice and high-accuracy equations for forest inventory were
tested. The selected Richards M1a generalized mixed-effects model simultaneously provides fixed and random
parameters to estimate the chestnut tree height from tree diameter and stand-level variables using the same
model. The analysis showed that the inclusion of dominant height and dominant diameter as predictors improved
the accuracy of the Richards model. The Draudt method was one of the best approaches to improve tree-level
height prediction accuracy using mixed-effects. The applied approach is quite feasible in 100–500 m2 plots.
The use of these models and the suggested calibration process will significantly reduce the effort and costs of
fieldwork teams to measure heights for forest management planning while ensuring high accuracy. This effort is greater the greater the forest density and, therefore, greater for young stands than for adult stands.Conception of the study, data analysis, drafting of the manuscript
and critical revision: MSP, LN, CRGD. Contributed materials: MSP, LN.
The authors are grateful to the Foundation for Science and Technology
(FCT, Portugal) for financial support by national funds FCT/
MCTES to CIMO (UIDB/00690/2020); AGRO Program, Project 267:
Sustainable Management of Chestnut Forested Areas in High-Forest and
Coppice Systems; Project PTDC/AGRCFL/68186/Mixed forests:
Modeling, dynamics and geographical distribution of productivity and
carbon storage in mixed forest ecosystems in Portugal; Project
PDR2020-101-031671 GO_FTA: Afforestation of agricultural lands with
+ value, financial support of FEADER and Portuguese Government.info:eu-repo/semantics/publishedVersio
Consent in Forensic Genetics as a Tool for Learning Human Rights
AbstractInformed consent is an ethical and legal requirement in research involving human beings. It includes the expression of the subject's autonomy upon the donation of biological material. The authors had previously recognized the high level of vulnerability of subjects referred for DNA testing at the Forensic Genetics Research Institute. In this work, they looked to improve the readability of the Informed Consent Term (ICT) and supported the donors’ comprehension process with the use of a comic strip, seeking for the expression of the information presented by the ICT. It was possible to present the donation process as an instrument for learning human rights
ON THE INTRINSIC CHARM COMPONENT OF THE NUCLEON
Using a meson cloud model we calculate the squared charm radius
of the nucleon . The ratio between this squared radius and the ordinary baryon
squared radius is identified with the probability of ``seeing'' the intrinsic
charm component of the nucleon. Our estimate is compatible with those used to
successfully describe the charm production phenomenology.Comment: 9 pages, 2 figures not included, avaiable from the author
Avaliação do potencial de produção de plantações de Castanea sativa Mill. instaladas ao abrigo do regulamento (CEE) 2080/92 na região de Bragança
O castanheiro é uma essência produtora de madeira para os mais diversos fins. Porém, a sua madeira só poderá ser considerada de qualidade quando o processo produtivo seja devidamente acompanhado com técnicas adequadas, desde a sua instalação até ao final do período de produção, que poderá ser mais ou menos longo, dependendo do objectivo. Ao abrigo do Regulamento (CEE) nº 2080/92 do Conselho, de 30 de Junho de 1992, que instituiu um regime comunitário de ajudas às medidas florestais na agricultura, foram
instaladas diversas plantações de castanheiro para madeira de qualidade. Neste trabalho recorre-se aos dados que resultaram da monitorização ao longo do tempo de parcelas permanentes representativas das plantações existentes em terrenos abandonados de agricultura. Com base nesses dados faz-se uma análise da produtividade atual das plantações e compara-se com a estimativa do seu potencial dado por modelos e tabelas de produção para a espécie.Financiado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) e pelo Estado Português no âmbito da Ação 1.1 "Grupos Operacionais", integrado na Medida I "Inovação" do PDR2020 - Programa de Desenvolvimento Rural do Continenteinfo:eu-repo/semantics/publishedVersio
Avaliação do potencial de produção de plantações de Castanea sativa Mill. instaladas ao abrigo do regulamento (CEE) 2080/92 na região de Bragança
Ao abrigo do Regulamento (CEE) nº 2080/92 do Conselho, de 30 de Junho de
1992, que institui um regime comunitário de ajudas às medidas florestais na agricultura,
foram instaladas diversas plantações de castanheiro para madeira de qualidade. É de
realçar que o castanheiro foi a folhosa mais utilizada nas arborizações em Trás-os-
Montes. Atualmente a espécie encontra-se em franca expansão, sobretudo em sistema
agroflorestal. Considerando a notória adaptabilidade da espécie às condições
edafoclimáticas do nordeste de Portugal, importa, pois, avaliar o estado destas plantações
e o seu potencial de produção agora com idades entre os 20-25 anos. Para tal recorre-se
aos dados que resultaram da monitorização ao longo do tempo de parcelas permanentes
representativas do estado das plantações existentes. Embora algumas plantações estejam
localizadas em boas classes de qualidade com potencial de produção elevado, constata-se
que o diâmetro médio fica abaixo do esperado devido à falta de silvicultura adequada,
nomeadamente a aplicação de desbastes para regulação da competição no entorno das
melhores árvores e cortes de formação e desramas para fomentar a qualidade individual
dos fustes das árvores de futuro. Neste trabalho faz-se uma análise da produtividade atual
das plantações e compara-se com a estimativa do seu potencial dado por modelos e tabelas
de produção para a espécie. Avalia-se a implicação da gestão efetuada no potencial de
produção para madeira de qualidade nesta região.Financiado pelo FEADER e pelo Estado Português, no âmbito da Ação 1.1 “Grupos Operacionais” integrado na Medida 1. Inovação do PDR 2020info:eu-repo/semantics/publishedVersio
Open‐source magnetic resonance imaging: improving access, science, and education through global collaboration
Open-source practices and resources in magnetic resonance imaging (MRI) have increased substantially in recent years. This trend started with software and data being published open-source and, more recently, open-source hardware designs have become increasingly available. These developments towards a culture of sharing and establishing nonexclusive global collaborations have already improved the reproducibility and reusability of code and designs, while providing a more inclusive approach, especially for low-income settings. Community-driven standardization and documentation efforts are further strengthening and expanding these milestones. The future of open-source MRI is bright and we have just started to discover its full collaborative potential. In this review we will give an overview of open-source software and open-source hardware projects in human MRI research
Motion-Compensation Techniques in Neonatal and Fetal MR Imaging
Fetal and neonatal MR imaging is increasingly used as a complementary diagnostic tool to sonography. MR imaging is an ideal technique for imaging fetuses and neonates because of the absence of ionizing radiation, the superior contrast of soft tissues compared with sonography, the availability of different contrast options, and the increased FOV. Motion in the normally mobile fetus and the unsettled, sleeping, or sedated neonate during a long acquisition will decrease image quality in the form of motion artifacts, hamper image interpretation, and often necessitate a repeat MR imaging to establish a diagnosis. This article reviews current techniques of motion compensation in fetal and neonatal MR imaging, including the following: 1) motion-prevention strategies (such as adequate patient preparation, patient coaching, and sedation, when required), 2) motion-artifacts minimization methods (such as fast imaging protocols, data undersampling, and motion-resistant sequences), and 3) motion-detection/correction schemes (such as navigators and self-navigated sequences, external motion-tracking devices, and postprocessing approaches) and their application in fetal and neonatal brain MR imaging. Additionally some background on the repertoire of motion of the fetal and neonatal patient and the resulting artifacts will be presented, as well as insights into future developments and emerging techniques of motion compensation
Influência das estações do ano na temperatura retal e freqüência respiratória de carneiros
Prolonged acceptance of skin grafts induced by B cells places regulatory T cells on the histopathology scene
Parâmetros genéticos de frutos, sementes e plântulas de Jatropha ribifolia (Pohl) Baill. (Euphorbiaceae)
- …