Modelling of an Optical Access Network Platform for Radio-Frequency Transmission in the S Band / Modelação de uma Plataforma de Rede de Acesso Óptico para Transmissão de Radiofrequências na Banda S

Microwave transmission in the S Band are used in WiMAX, mobile telephony, air control and satellite communications. Such applications demand the use of wideband optical access networks. In this article, the impact of non-linearities of a fluorescent optical source (FFOS) is analyzed on the performance, at 560 nm, of Discrete-Multitone (DMT) transmissions, using the multicarrier signal-to-noise ratio  (SNRmc) metric. The objective is to provide a  model of SNRmc level curves based on empirical measurements by varying the bias current and the amplitude of the input signal in the optical source. The cartography was approximated by fitting ellipses, which allows us to find an approximate optimum point of operation for the setup.

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

ATLANTIC EPIPHYTES: a data set of vascular and non-vascular epiphyte plants and lichens from the Atlantic Forest

Epiphytes are hyper-diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non-vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence and abundance; (2) describe the epiphyte distribution in the Atlantic Forest, in order to indicate future sampling efforts. Our work presents the first epiphyte data set with information on abundance and occurrence of epiphyte phorophyte species. All data compiled here come from three main sources provided by the authors: published sources (comprising peer-reviewed articles, books, and theses), unpublished data, and herbarium data. We compiled a data set composed of 2,095 species, from 89,270 holo/hemiepiphyte records, in the Atlantic Forest of Brazil, Argentina, Paraguay, and Uruguay, recorded from 1824 to early 2018. Most of the records were from qualitative data (occurrence only, 88%), well distributed throughout the Atlantic Forest. For quantitative records, the most common sampling method was individual trees (71%), followed by plot sampling (19%), and transect sampling (10%). Angiosperms (81%) were the most frequently registered group, and Bromeliaceae and Orchidaceae were the families with the greatest number of records (27,272 and 21,945, respectively). Ferns and Lycophytes presented fewer records than Angiosperms, and Polypodiaceae were the most recorded family, and more concentrated in the Southern and Southeastern regions. Data on non-vascular plants and lichens were scarce, with a few disjunct records concentrated in the Northeastern region of the Atlantic Forest. For all non-vascular plant records, Lejeuneaceae, a family of liverworts, was the most recorded family. We hope that our effort to organize scattered epiphyte data help advance the knowledge of epiphyte ecology, as well as our understanding of macroecological and biogeographical patterns in the Atlantic Forest. No copyright restrictions are associated with the data set. Please cite this Ecology Data Paper if the data are used in publication and teaching events. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ

Catálogo Taxonômico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the Catálogo Taxonômico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Multiplexação DMT em fibras de plástico utilizando fontes ópticas em 450, 520, 560 e 650 nm

Este trabalho tem como objetivo demonstrar um sistema de transmissão utilizando mutliplexação Discrete Multitone (DMT) para melhorar a eficiência espectral e aumentar a taxa de transmissão em enlaces de curta distância utilizando fibras óticas poliméricas. Assim, foi desenvolvido um esquema de multiplexação DMT modificado, com intuito de mitigar os efeitos dispersivos do canal (POF). Para demonstrar a eficiência do algorı́tmo de multiplexação foi utilizado um enlace de 20 m de fibra ótica de plástico de polimetilmetacrilato de índice degrau e quatro fontes ópticas de baixo custo, feitas para iluminação, com largura de banda analógica da ordem de 20 MHz. Uma dessas fontes foi desenvolvida no Laboratório de Comunicações Óticas (LACOP) da Universidade Federal Fluminense (UFF). Os resultados experimentais demonstraram uma eficiência espectral de 6.39bits/s/Hz para uma taxa de erro de bit (BER) alvo de 10 −3 oferecendo grande potencial, assim como a fonte óptica desenvolvida, para a implementação de um sistema de multiplexação por divisão de comprimentos de ondaThis work aims to demonstrate a transmission system using DMT mutliplexation to improve spectral efficiency and increase the rate of transmission in short distance links using polymer optical fibers. Thus, a modified DMT multiplexing scheme was developed in order to mitigate the dispersive effects of the channel (POF). To demonstrate the efficiency of the multiplexing algorithm, a 20-m link of step-index polymethylmethacrylate plastic fiber optic link and four low-cost optical sources, made for illumination, with an analog bandwidth of the order of 20 MHz. One of these sources was developed in the Laboratory of Optical Communications (LACOP) of the Universidade Federal Fluminense (UFF). The experimental results demonstrated a spectral efficiency of 6.39 bits/s/Hz for a target bit error rate (BER) of 10 −3 offering great potential, as well as the developed optical source, for the implementation of a system of wavelength division multiplexin

Etude des techniques de compensation numérique pour les réseaux d'accès optique 50G-PON

Over the next years, the required bit rates for access networks are immense due to the massive increase of connected devices and bandwidth-hungry applications. Passive Optical Networks (PON) are the conventional choice for access works because they ally low cost and have high transmission rate capacity. As industry researchers participating in standardization committees ITU-T and IEEE target increasing the single channel capacity from 10 Gbit/s to 25Gbit/s, 50Gbit/s, and even100 Gbit/s, this thesis focuses on digital compensation techniques for the 50G-PON since the optical channel is critically impaired by chromatic dispersion, chirp, bandwidth limitation, and attenuation. The work was organized as follows: • We used two models that approximate the real conditions of a PON based on Intensity Modulation and Direct Detection (IM/DD), a small-signal model constructed in MATLAB© and a large signal model via VPI Transmission Maker™. • We perform Intersymbol Interference (ISI) compensation through Minimum Mean Square Error (MMSE) based equalization and Maximum Likelihood Sequence Detection (MLSE). Also, closed-form equations were used to predict the performance of the equalizers. • Finally, we realized experimental transmissions in Orange’s 50Gbit/s laboratory followed by offline processing. The experimental measurements were compared to the simulated IM/DD model, and the three DSP-based receivers were evaluated in practice.Au cours des prochaines années, les débits requis pour les réseaux d'accès seront immenses en raison de l'augmentation massive des appareils connectés et du nombre d’applications gourmandes en bande passante. Les réseaux optiques passifs (PON) sont le choix classique pour les réseaux d'accès car ils allient un faible coût et une capacité de débit de transmission élevée. Les chercheurs de l’industrie travaillent au sein des groupes de normalisation ITU-T et IEEE à augmenter la capacité d’un canal optique de 10 Gbit/s vers 25Gbit/s, 50 Gbit/s et même 100 Gbit/s. Cette thèse se concentre sur les techniques de compensation numérique pour le 50G-PON parce que c’est l’évolution qui devrait être déployée en premier sur le terrain et que le canal optique est gravement impacté par la dispersion chromatique, le chirp, la limitation de la bande passante et l'atténuation. Le travail a été organisé comme suit : • Nous avons étudié la compensation des interférences intersymbole (ISI) via l'égalisation linéaire, l’égalisation à retour de décision (LE et DFE respectivement) basées sur le critère d'erreur quadratique moyenne minimale (MMSE), et montré comment prédire les performances de l’égaliseur au moyen d’équations simples, sur la base d’un modèle du canal. Ensuite, l’utilisation d’un récepteur optimal au sens du maximum de vraisemblance (MLSE). • Enfin, nous avons réalisé des transmissions expérimentales dans le laboratoire 50Gbit/s d'Orange ensuite le traitement numérique des signaux obtenus. Les mesures expérimentales ont conforté le modèle IM/DD simulé, et les trois récepteurs basés sur le DSP ont été évalués en conditions réelles

Etude des techniques de compensation numérique pour les réseaux d'accès optique 50G-PON

Over the next years, the required bit rates for access networks are immense due to the massive increase of connected devices and bandwidth-hungry applications. Passive Optical Networks (PON) are the conventional choice for access works because they ally low cost and have high transmission rate capacity. As industry researchers participating in standardization committees ITU-T and IEEE target increasing the single channel capacity from 10 Gbit/s to 25Gbit/s, 50Gbit/s, and even100 Gbit/s, this thesis focuses on digital compensation techniques for the 50G-PON since the optical channel is critically impaired by chromatic dispersion, chirp, bandwidth limitation, and attenuation. The work was organized as follows: • We used two models that approximate the real conditions of a PON based on Intensity Modulation and Direct Detection (IM/DD), a small-signal model constructed in MATLAB© and a large signal model via VPI Transmission Maker™. • We perform Intersymbol Interference (ISI) compensation through Minimum Mean Square Error (MMSE) based equalization and Maximum Likelihood Sequence Detection (MLSE). Also, closed-form equations were used to predict the performance of the equalizers. • Finally, we realized experimental transmissions in Orange’s 50Gbit/s laboratory followed by offline processing. The experimental measurements were compared to the simulated IM/DD model, and the three DSP-based receivers were evaluated in practice.Au cours des prochaines années, les débits requis pour les réseaux d'accès seront immenses en raison de l'augmentation massive des appareils connectés et du nombre d’applications gourmandes en bande passante. Les réseaux optiques passifs (PON) sont le choix classique pour les réseaux d'accès car ils allient un faible coût et une capacité de débit de transmission élevée. Les chercheurs de l’industrie travaillent au sein des groupes de normalisation ITU-T et IEEE à augmenter la capacité d’un canal optique de 10 Gbit/s vers 25Gbit/s, 50 Gbit/s et même 100 Gbit/s. Cette thèse se concentre sur les techniques de compensation numérique pour le 50G-PON parce que c’est l’évolution qui devrait être déployée en premier sur le terrain et que le canal optique est gravement impacté par la dispersion chromatique, le chirp, la limitation de la bande passante et l'atténuation. Le travail a été organisé comme suit : • Nous avons étudié la compensation des interférences intersymbole (ISI) via l'égalisation linéaire, l’égalisation à retour de décision (LE et DFE respectivement) basées sur le critère d'erreur quadratique moyenne minimale (MMSE), et montré comment prédire les performances de l’égaliseur au moyen d’équations simples, sur la base d’un modèle du canal. Ensuite, l’utilisation d’un récepteur optimal au sens du maximum de vraisemblance (MLSE). • Enfin, nous avons réalisé des transmissions expérimentales dans le laboratoire 50Gbit/s d'Orange ensuite le traitement numérique des signaux obtenus. Les mesures expérimentales ont conforté le modèle IM/DD simulé, et les trois récepteurs basés sur le DSP ont été évalués en conditions réelles