38 research outputs found
Suporte de mobilidade em redes WIMAX
O desenvolvimento crescente da Internet, com novos serviços e
aplicações que requerem elevadas exigências a nível de qualidade de
serviço, como por exemplo, o VoIP e IPTV, a crescente necessidade de
um utilizador estar sempre contactável em qualquer sítio e a qualquer
momento, torna necessária a integração actual da Internet com as redes
móveis da próxima geração.
A tecnologia IEEE 802.16 surge como uma tecnologia de banda larga
sem fios que pode ter um papel fundamental num ambiente de próxima
geração. Devido aos seus baixos custos de instalação e à possibilidade de
chegar facilmente a zonas rurais ou a zonas de difícil acesso, torna-se um
sério candidato para suprir as necessidades dos utilizadores.
A necessidade de mobilidade pelo utilizador, para aceder a diversos
serviços em diferentes sítios ou ser identificado remotamente para a
posterior recepção de informação também é um desejo futuro.
O protocolo IEEE 802.21 surge como um meio que providencia a
optimização de handover entre diferentes tecnologias de acesso, quer
sejam elas WiFi, WiMAX, 3GGP ou 3GPP2, no sentido de proporcionar
ao utilizador a utilização de diferentes serviços de uma forma
transparente à tecnologia de acesso, quando em situações de mobilidade.
Esta dissertação apresenta a arquitectura desenvolvida para proporcionar
a correcta avaliação da atribuição de QoS e mobilidade transparente,
num ambiente real de próxima geração. Serão também efectuados testes
com o equipamento WiMAX disponível, no sentido de mostrar o seu
correcto comportamento na atribuição de QoS fim-a-fim em cenários
ponto-a-ponto e ponto-a-multiponto com serviços com características de
tempo real. A integração do software da primeira fase do projecto
WEIRD e o seu correcto comportamento em ambientes de atribuição de
QoS também vai ser estudado. A implementação dos diferentes módulos,
em especial a implementação da unidade central da arquitectura de IEEE
802.21 (MIHF), vai ser descrita, no sentido de avaliar o desempenho do
WiMAX e do protocolo IEEE 802.21 numa rede real no âmbito da
segunda fase do projecto WEIRD. Os resultados obtidos demonstram
que a arquitectura desenvolvida consegue fornecer QoS fim-a-fim com
suporte de mobilidade entre redes heterogéneas.
ABSTRACT: The growing development of the Internet, with new services and
applications that require a high level of quality of service, such as, VoIP
and IPTV, the increasing need for a user to be always reachable
anywhere and at anytime, motivates the integration of current Internet
with the next generation of mobile networks.
The IEEE 802.16 technology emerges as a technology for broadband
wireless access that may have a key role in a next generation
environment. Due to its low costs of installation and its ability to easily
reach rural areas or areas with difficult access, it becomes a serious
candidate to supply the needs of users.
The mobility’s necessity by the user, to access to several services in
different locations or be identified remotely for subsequent receipt of
information, is also a future desire.
The IEEE 802.21 protocol provides the optimization of handover
between heterogeneous networks, such as WiFi, WiMAX, 3GGP or
3GPP2, to offer the user different services in a transparent manner to his
access technology, when in situations of mobility.
This Thesis presents the architecture developed to provide the correct
integration of QoS and seamless mobility, in a real next generation
environment. It will also present tests carries out with the available
WiMAX equipment, to show its correct behaviour in the allocation of
end-to-end QoS in point-to-point and point-to-multipoint scenarios with
real-time services. The integration of software from the first phase of the
WEIRD project and its correct behaviour in environments of QoS
allocation will also be studied. The implementation of the various
modules, in particular the implementation of the central unit of IEEE
802.21 architecture (MIHF), will be described, to evaluate the
performance of WiMAX and IEEE 802.21 protocol in a real network
provided by the second phase of the WEIRD project. The obtained
results show that the developed architecture is able to provide end-toend
QoS with seamless mobility support over heterogeneous networks
Redes em malha sem fios baseadas em contexto
Doutoramento em Engenharia ElectrotécnicaIn the modern society, new devices, applications and technologies, with sophisticated
capabilities, are converging in the same network infrastructure.
Users are also increasingly demanding in personal preferences and expectations,
desiring Internet connectivity anytime and everywhere. These aspects
have triggered many research efforts, since the current Internet is reaching
a breaking point trying to provide enough flexibility for users and profits for
operators, while dealing with the complex requirements raised by the recent
evolution.
Fully aligned with the future Internet research, many solutions have been
proposed to enhance the current Internet-based architectures and protocols,
in order to become context-aware, that is, to be dynamically adapted to
the change of the information characterizing any network entity. In this
sense, the presented Thesis proposes a new architecture that allows to create
several networks with different characteristics according to their context, on
the top of a single Wireless Mesh Network (WMN), which infrastructure
and protocols are very flexible and self-adaptable.
More specifically, this Thesis models the context of users, which can span
from their security, cost and mobility preferences, devices’ capabilities or
services’ quality requirements, in order to turn a WMN into a set of logical
networks. Each logical network is configured to meet a set of user context
needs (for instance, support of high mobility and low security). To
implement this user-centric architecture, this Thesis uses the network virtualization,
which has often been advocated as a mean to deploy independent
network architectures and services towards the future Internet, while allowing
a dynamic resource management. This way, network virtualization can
allow a flexible and programmable configuration of a WMN, in order to be
shared by multiple logical networks (or virtual networks - VNs). Moreover,
the high level of isolation introduced by network virtualization can be used
to differentiate the protocols and mechanisms of each context-aware VN.
This architecture raises several challenges to control and manage the VNs
on-demand, in response to user and WMN dynamics. In this context, we
target the mechanisms to: (i) discover and select the VN to assign to an
user; (ii) create, adapt and remove the VN topologies and routes. We
also explore how the rate of variation of the user context requirements can
be considered to improve the performance and reduce the complexity of
the VN control and management. Finally, due to the scalability limitations
of centralized control solutions, we propose a mechanism to distribute the
control functionalities along the architectural entities, which can cooperate
to control and manage the VNs in a distributed way.Na sociedade actual, novos dispositivos, aplicações e tecnologias, com capacidades
sofisticadas, estão a convergir na mesma infra-estrutura de rede.
Os utilizadores são também cada vez mais exigentes nas suas preferências e
expectativas pessoais, desejando conetividade `a Internet em qualquer hora
e lugar. Estes aspectos têm desencadeado muitos esforços de investigação,
dado que a Internet atual está a atingir um ponto de rutura ao tentar promover
flexibilidade para os utilizadores e lucros para os operadores, enquanto
lida com as exigências complexas associadas `a recente evolução.
Em sintonia com a linha de investigação para a Internet do futuro, muitas
soluções têm sido propostas para melhorar as arquiteturas e protocolos da
Internet atual, de forma a torná-los sensíveis ao contexto, isto é, adaptá-los
dinamicamente `a alteração da informação que caracteriza qualquer entidade
de rede. Neste sentido, a presente Tese propõe uma nova arquitetura que
permite criar várias redes com diferentes características de acordo com o
contexto das mesmas, sobre uma única rede em malha sem fios (WMN),
cuja infra-estructura e protocolos são muito flexíveis e auto-adaptáveis.
Mais especificamente, esta Tese modela o contexto dos utilizadores, que
pode abranger as suas preferências de segurança, custo e mobilidade, capacidades
dos seus dispositivos ou requisitos de qualidade dos seus serviços,
de forma a transformar uma WMN num conjunto de redes lógicas. Cada
rede lógica ´e configurada para satisfazer um conjunto de necessidades de
contexto do utilizador (como exemplo, suporte de mobilidade elevada e
de baixa seguran¸ca). Para implementar esta arquitetura centrada no utilizador,
esta Tese utiliza a virtualização de redes, que tem muitas vezes
sido defendida como um meio para implementar arquiteturas e serviços de
rede de uma forma independente, enquanto permite uma gestão dinâmica
dos recursos. Desta forma, a virtualização de redes pode permitir uma
configuração flexível e programável de uma WMN, a fim de ser partilhada
por várias redes lógicas (ou redes virtuais - VNs). Além disso, o grau de
isolamento introduzido pela virtualização de redes pode ser utilizado para
diferenciar os protocolos e mecanismos de cada VN baseada em contexto.
Esta arquitetura levanta vários desafios para controlar e gerir as VNs em
tempo real, e em resposta `a dinâmica dos utilizadores e da WMN. Neste
contexto, abordamos os mecanismos para: (i) descobrir e selecionar a VN
a atribuir a um utilizador; (ii) criar, adaptar e remover as topologias e
rotas das VNs. Também exploramos a possibilidade de considerar a taxa
de variação dos requisitos de contexto dos utilizadores de forma a melhorar
o desempenho e reduzir a complexidade do controlo e gestão das VNs.
Finalmente, devido ´as limitações de escalabilidade das soluções de controlo
centralizadas, propomos um mecanismo para distribuir as funcionalidades
de controlo ao longo das entidades da arquitectura, que podem cooperar
para controlar e gerir as VNs de uma forma distribuída
Artificial intelligence to growth stresses predicting in Eucalyptus clones using dendrometric variables and wood density
Eucalyptus planted forests contribute to maximizing lumber production but problems such as longitudinal growth strain can negatively influence the quality of the products. Knowing dendrometric variables and wood properties can help in the prediction of longitudinal growth strain, mainly with the help of artificial intelligence. Thus, the aim of this research was to evaluate the use of artificial neural networks to predict longitudinal growth strain in Eucalyptus trees based on dendrometric variables, spacing between trees and wood density. The longitudinal growth strain was measured in trees of four Eucalyptus clones planted in three spacings. The diameter and height of each tree were measured. The basic wood density was determined. Artificial neural networks were used to estimate longitudinal growth strain as a function of dendrometric variables, tree spacing and wood density. The results showed that the artificial neural networks presented good results for training and validation, with most of them resulting in high correlation coefficient values. The trained artificial neural networks showed a correlation coefficient above 0,56. Artificial neural networks showed that the variables clone and basic wood density were the ones that most contributed to the prediction of longitudinal growth strain. On the other hand, the spacing between trees, the height of the tree and the diameter at breast height were not relevant to predict growth stresses
SARS-CoV-2 introductions and early dynamics of the epidemic in Portugal
Genomic surveillance of SARS-CoV-2 in Portugal was rapidly implemented by
the National Institute of Health in the early stages of the COVID-19 epidemic, in collaboration
with more than 50 laboratories distributed nationwide.
Methods By applying recent phylodynamic models that allow integration of individual-based
travel history, we reconstructed and characterized the spatio-temporal dynamics of SARSCoV-2 introductions and early dissemination in Portugal.
Results We detected at least 277 independent SARS-CoV-2 introductions, mostly from
European countries (namely the United Kingdom, Spain, France, Italy, and Switzerland),
which were consistent with the countries with the highest connectivity with Portugal.
Although most introductions were estimated to have occurred during early March 2020, it is
likely that SARS-CoV-2 was silently circulating in Portugal throughout February, before the
first cases were confirmed.
Conclusions Here we conclude that the earlier implementation of measures could have
minimized the number of introductions and subsequent virus expansion in Portugal. This
study lays the foundation for genomic epidemiology of SARS-CoV-2 in Portugal, and highlights the need for systematic and geographically-representative genomic surveillance.We gratefully acknowledge to Sara Hill and Nuno Faria (University of Oxford) and
Joshua Quick and Nick Loman (University of Birmingham) for kindly providing us with
the initial sets of Artic Network primers for NGS; Rafael Mamede (MRamirez team,
IMM, Lisbon) for developing and sharing a bioinformatics script for sequence curation
(https://github.com/rfm-targa/BioinfUtils); Philippe Lemey (KU Leuven) for providing
guidance on the implementation of the phylodynamic models; Joshua L. Cherry
(National Center for Biotechnology Information, National Library of Medicine, National
Institutes of Health) for providing guidance with the subsampling strategies; and all
authors, originating and submitting laboratories who have contributed genome data on
GISAID (https://www.gisaid.org/) on which part of this research is based. The opinions
expressed in this article are those of the authors and do not reflect the view of the
National Institutes of Health, the Department of Health and Human Services, or the
United States government. This study is co-funded by Fundação para a Ciência e Tecnologia
and Agência de Investigação Clínica e Inovação Biomédica (234_596874175) on
behalf of the Research 4 COVID-19 call. Some infrastructural resources used in this study
come from the GenomePT project (POCI-01-0145-FEDER-022184), supported by
COMPETE 2020 - Operational Programme for Competitiveness and Internationalisation
(POCI), Lisboa Portugal Regional Operational Programme (Lisboa2020), Algarve Portugal
Regional Operational Programme (CRESC Algarve2020), under the PORTUGAL
2020 Partnership Agreement, through the European Regional Development Fund
(ERDF), and by Fundação para a Ciência e a Tecnologia (FCT).info:eu-repo/semantics/publishedVersio
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
Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world
Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic.
Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality.
Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States.
Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis.
Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection
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
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Abstract
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries
Mídia e política no Brasil: textos e agenda de pesquisa Midia and politics in Brazil: texts and research agenda
Um especialista em estudos de comunicação e um cientista político apresentam conjuntamente um panorama da pesquisa sobre as relações entre os meios de comunicação e os processos políticos no Brasil. Uma agenda de pesquisa é proposta e um elenco de textos nessa área é apresentado.<br>A specialist in communication studies and a political scientist present together a panorama of research on the relations between communication midia and political processes in Brazil A research agenda is proposed and a list of texts in this area is presented