133 research outputs found
Concepção e implementação de experiĂȘncias laboratoriais sobre MPLS
Mestrado em Engenharia Electrónica e TelecomunicaçÔesO Multiprotocol Label Switching (MPLS) é um mecanismo de
transporte de dados, sob a forma de um protocolo agnĂłstico, com
grande potencial de crescimento e adequação. Opera na âCamada 2.5â
do modelo OSI e constitui um mecanismo de alto desempenho utilizado
nas redes de nĂșcleo para transportar dados de um nĂł da rede para outro.
O sucesso do MPLS resulta do facto de permitir que a rede transporte
todos os tipos de dados, desde trĂĄfego IP a trĂĄfego da camada de
ligação de dados, devido ao encapsulamento dos pacotes dos diversos
protocolos, permitindo a criação de âlinks virtuaisâ entre nĂłs distantes.
O MPLS pertence Ă famĂlia das âredes de comutação de pacotesâ,
sendo os pacotes de dados associados a âetiquetasâ que determinam o
seu encaminhamento, sem necessidade de examinar o conteĂșdo dos
prĂłprios pacotes. Isto permite a criação de circuitos âextremo-aextremoâ
através de qualquer tipo de rede de transporte e
independentemente do protocolo de encaminhamento que Ă© utilizado.
O projecto do MPLS considera mĂșltiplas tecnologias no sentido de
prestar um serviço Ășnico de transporte de dados, tentando
simultaneamente proporcionar capacidades de engenharia de trĂĄfego e
controlo âout-of-bandâ, uma caracterĂstica muito atraente para uma
implementação em grande escala. No fundo, o MPLS é uma forma de
consolidar muitas redes IP dentro de uma Ășnica rede.
Dada a importĂąncia desta tecnologia, Ă© urgente desenvolver ferramentas
que permitam entender melhor a sua complexidade. O MPLS corre
normalmente nas redes de nĂșcleo dos ISPs. No sentido de tornar o seu
estudo viåvel, recorreu-se nesta dissertação à emulação para
implementar cenĂĄrios de complexidade adequada. Existem actualmente
boas ferramentas disponĂveis que permitem a recriação em laboratĂłrio
de cenĂĄrios bastante complicados.
Contudo, a exigĂȘncia computacional da emulação Ă© proporcional Ă
complexidade do projecto em questĂŁo, tornando-se rapidamente
impossĂvel de realizar numa Ășnica mĂĄquina. A computação distribuĂda
ou a âCloud Computingâ sĂŁo actualmente as abordagens mais
adequadas e inovadoras apara a resolução deste problema.
Esta dissertação tem como objectivo criar algumas experiĂȘncias em
laboratĂłrio que evidenciam aspectos relevantes da tecnologia MPLS,
usando para esse efeito um emulador computacional, o Dynamips,
impulsionado por generosas fontes computacionais disponibilizadas
pela Amazon ec2. A utilização destas ferramentas de emulação permite
testar cenårios de rede e serviços reais em ambiente controlado,
efectuando o debugging das suas configuraçÔes e optimizando o seu
desempenho, antes de os colocar em funcionamento nas redes em
operação.The Multiprotocol Label Switching (MPLS) is a highly scalable and
agnostic protocol to carry network data.
Operating at "Layer 2.5" of the OSI model, MPLS is an highperformance
mechanism that is used at the network backbone for
conveying data from one network node to the next.
The success of MPLS results from the fact that it enables the network to
carry all kinds of traffic, ranging from IP to layer 2 traffic, since it
encapsulates the packets of the diverse network protocols, allowing the
creation of "virtual links" between distant nodes.
MPLS belongs to the family of packet switched networks, where labels
are assigned to data packets that are forwarded based on decisions that
rely only on the label contents, without the need to examine the packets
contents. This allows the creation of end-to-end circuits across any type
of transport medium, using any protocol.
The MPLS design takes multiform transport technologies into account to
provide a unified data-carrying service, attempting simultaneously to
preserve traffic engineering and out-of-band control, a very attractive
characteristic for large-scale deployment. MPLS is the way to
consolidate many IP networks into a single one. Due to this obvious
potential, it is urgent to develop means and tools to better understand its
functioning and complexity.
MPLS normally runs at the backbone of Service Providers networks,
being deployed across an extensive set of expensive equipment. In order
to turn the study of MPLS feasible, emulation was considered as the best
solution. Currently, there are very good available tools to recreate, in a
lab environment, quite complicated scenarios.
However, the computational demand of the emulation is proportional to
the complexity of the project, becoming quickly unfeasible in a single
machine.
Fortunately, distributed computing or Cloud computing are suitable and
novel approaches to solve this computation problem.
So, this work aims to create some lab experiments that can
illustrate/demonstrate relevant aspects of the MPLS technology, using the
Dynamips emulator driven by the computational resources that were
made available by the Amazon ec2 cloud computing facilities. The
utilization of these emulation tools allows testing real networks and
service scenarios in a controlled environment, being able to debug their
configurations and optimize their performance before deploying them in
real operating networks
The effect of protein supplementation on body muscle mass and fat mass in post-bariatric surgery: a randomized controlled trial (RCT) study protocol
A Comparative Study on the WCRF International/University of Bristol Methodology for Systematic Reviews of Mechanisms Underpinning Exposure-Cancer Associations
The World Cancer Research Fund (WCRF) International and the University of Bristol have developed a novel framework for providing an overview of mechanistic pathways and conducting a systematic literature review of the biologically plausible mechanisms underlying exposure-cancer associations. Two teams independently applied the two-stage framework on mechanisms underpinning the association between body fatness and breast cancer to test the framework feasibility and reproducibility as part of a WCRF-commissioned validation study. In stage I, a "hypothesis-free" approach was used to provide an overview of potential intermediate mechanisms between body fatness and breast cancer. Dissimilar rankings of potential mechanisms were observed between the two teams due to different applications of the framework. In stage II, a systematic review was conducted on the insulin-like growth factor 1 receptor (IGF1R) chosen as an intermediate mechanism. Although the studies included differed, both teams found inconclusive evidence for the body fatness-IGF1R association and modest evidence linking IGF1R to breast cancer, and therefore concluded that there is currently weak evidence for IGF1R as mechanism linking body fatness to breast cancer. The framework is a good starting point for conducting systematic reviews by integrating evidence from mechanistic studies on exposure-cancer associations. On the basis of our experience, we provide recommendations for future users. (C) 2017 AACR
Effects of supplemented isoenergetic diets varying in cereal fiber and protein content on the bile acid metabolic signature and relation to insulin resistance
Bile acids (BA) are potent metabolic regulators influenced by diet. We studied effects of isoenergetic increases in the dietary protein and cereal-fiber contents on circulating BA and insulin resistance (IR) in overweight and obese adults. Randomized controlled nutritional intervention (18 weeks) in 72 non-diabetic participants (overweight/obese: 29/43) with at least one further metabolic risk factor. Participants were group-matched and allocated to four isoenergetic supplemented diets: control; high cereal fiber (HCF); high-protein (HP); or moderately increased cereal fiber and protein (MIX). Whole-body IR and insulin-mediated suppression of hepatic endogenous glucose production were measured using euglycaemicâhyperinsulinemic clamps with [6-62H2] glucose infusion. Circulating BA, metabolic biomarkers, and IR were measured at 0, 6, and 18 weeks. Under isoenergetic conditions, HP-intake worsened IR in obese participants after 6 weeks (M-value: 3.77â±â0.58 vs. 3.07â±â0.44âmg/kg/min, pâ=â0.038), with partial improvement back to baseline levels after 18 weeks (3.25â±â0.45âmg/kg/min, pâ=â0.089). No deleterious effects of HP-intake on IR were observed in overweight participants. HCF-diet improved IR in overweight participants after 6 weeks (M-value 4.25â±â0.35 vs. 4.81â±â0.31âmg/kg/min, pâ=â0.016), but did not influence IR in obese participants. Control and MIX diets did not influence IR. HP-induced, but not HCF-induced changes in IR strongly correlated with changes of BA profiles. MIX-diet significantly increased most BA at 18 weeks in obese, but not in overweight participants. BA remained unchanged in controls. Pooled BA concentrations correlated with fasting fibroblast growth factor-19 (FGF-19) plasma levels (râ=â0.37; pâ=â0.003). Higher milk protein intake was the only significant dietary predictor for raised total and primary BA in regression analyses (total BA, pâ=â0.017; primary BA, pâ=â0.011). Combined increased intake of dietary protein and cereal fibers markedly increased serum BA concentrations in obese, but not in overweight participants. Possible mechanisms explaining this effect may include compensatory increases of the BA pool in the insulin resistant, obese state; or defective BA transport
Recommended from our members
Fecal microbiota and bile acid interactions with systemic and adipose tissue metabolism in diet-induced weight loss of obese postmenopausal women
Microbiota and bile acids in the gastrointestinal tract profoundly alter systemic metabolic processes. In obese subjects, gradual weight loss ameliorates adipose tissue inflammation and related systemic changes. We assessed how rapid weight loss due to a very low calorie diet (VLCD) affects the fecal microbiome and fecal bile acid composition, and their interactions with the plasma metabolome and subcutaneous adipose tissue inflammation in obesity. We performed a prospective cohort study of VLCD-induced weight loss of 10% in ten grades 2-3 obese postmenopausal women in a metabolic unit. Baseline and post weight loss evaluation included fasting plasma analyzed by mass spectrometry, adipose tissue transcription by RNA sequencing, stool 16S rRNA sequencing for fecal microbiota, fecal bile acids by mass spectrometry, and urinary metabolic phenotyping by H-NMR spectroscopy. Outcome measures included mixed model correlations between changes in fecal microbiota and bile acid composition with changes in plasma metabolite and adipose tissue gene expression pathways. Alterations in the urinary metabolic phenotype following VLCD-induced weight loss were consistent with starvation ketosis, protein sparing, and disruptions to the functional status of the gut microbiota. We show that the core microbiome was preserved during VLCD-induced weight loss, but with changes in several groups of bacterial taxa with functional implications. UniFrac analysis showed overall parallel shifts in community structure, corresponding to reduced abundance of the genus Roseburia and increased Christensenellaceae;g__ (unknown genus). Imputed microbial functions showed changes in fat and carbohydrate metabolism. A significant fall in fecal total bile acid concentration and reduced deconjugation and 7-α-dihydroxylation were accompanied by significant changes in several bacterial taxa. Individual bile acids in feces correlated with amino acid, purine, and lipid metabolic pathways in plasma. Furthermore, several fecal bile acids and bacterial species correlated with altered gene expression pathways in adipose tissue. VLCD dietary intervention in obese women changed the composition of several fecal microbial populations while preserving the core fecal microbiome. Changes in individual microbial taxa and their functions correlated with variations in the plasma metabolome, fecal bile acid composition, and adipose tissue transcriptome
Recommended from our members
Systematic review of the effects of the intestinal microbiota on selected nutrients and non-nutrients
The systematic review demonstrates that the IM plays a major role in the breakdown and transformation of the dietary substrates examined. However, recent human data are limited with the exception of data from studies examining fibres and polyphenols. Results observed in relation with dietary substrates were not always consistent or coherent across studies and methodological limitations and differences in IM analyses made comparisons difficult. Moreover, non-digestible components likely to reach the colon are often not well defined or characterised in studies making comparisons between studies difficult if not impossible. Going forward, further rigorously controlled randomised human trials with well-defined dietary substrates and utilizing omic-based technologies to characterise and measure the IM and their functional activities will advance the field. Current evidence suggests that more detailed knowledge of the metabolic activities and interactions of the IM hold considerable promise in relation with host health
Framework and baseline examination of the German National Cohort (NAKO)
The German National Cohort (NAKO) is a multidisciplinary, population-based prospective cohort study that aims to investigate the causes of widespread diseases, identify risk factors and improve early detection and prevention of disease. Specifically, NAKO is designed to identify novel and better characterize established risk and protection factors for the development of cardiovascular diseases, cancer, diabetes, neurodegenerative and psychiatric diseases, musculoskeletal diseases, respiratory and infectious diseases in a random sample of the general population. Between 2014 and 2019, a total of 205,415 men and women aged 19â74Â years were recruited and examined in 18 study centres in Germany. The baseline assessment included a face-to-face interview, self-administered questionnaires and a wide range of biomedical examinations. Biomaterials were collected from all participants including serum, EDTA plasma, buffy coats, RNA and erythrocytes, urine, saliva, nasal swabs and stool. In 56,971 participants, an intensified examination programme was implemented. Whole-body 3T magnetic resonance imaging was performed in 30,861 participants on dedicated scanners. NAKO collects follow-up information on incident diseases through a combination of active follow-up using self-report via written questionnaires at 2â3Â year intervals and passive follow-up via record linkages. All study participants are invited for re-examinations at the study centres in 4â5Â year intervals. Thereby, longitudinal information on changes in risk factor profiles and in vascular, cardiac, metabolic, neurocognitive, pulmonary and sensory function is collected. NAKO is a major resource for population-based epidemiology to identify new and tailored strategies for early detection, prediction, prevention and treatment of major diseases for the next 30Â years. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10654-022-00890-5
Design und QualitÀtskontrolle der zahnmedizinischen Untersuchung in der NAKO Gesundheitsstudie [Design and quality control of the oral health status examination in the German National Cohort (GNC)]
BACKGROUND: Caries and periodontitis are highly prevalent worldwide. Because detailed data on these oral diseases were collected within the framework of the German National Cohort (GNC), associations between oral and systemic diseases and conditions can be investigated. OBJECTIVES: The study protocol for the oral examination was designed to ensure a comprehensive collection of dental findings by trained non-dental staff within a limited examination time. At the mid-term of the GNC baseline examination, a first quality evaluation was performed to check the plausibility of results and to propose measures to improve the data quality. MATERIALS AND METHODS: A dental interview, saliva sampling and oral diagnostics were conducted. As part of the levelâ1 examination, the number of teeth and prostheses were recorded. As part of the levelâ2 examination, detailed periodontal, cariological and functional aspects were examined. All examinations were conducted by trained non-dental personnel. Parameters were checked for plausibility and variable distributions were descriptively analysed. RESULTS: Analyses included data of 57,967 interview participants, 56,913 levelâ1 participants and 6295 levelâ2 participants. Percentages of missing values for individual clinical parameters assessed in level 1 and level 2 ranged between 0.02 and 3.9%. Results showed a plausible distribution of the data; rarely, implausible values were observed, e.g. for measurements of horizontal and vertical overbite (overjet and overbite). Intra-class correlation coefficients indicated differences in individual parameters between regional clusters, study centres and across different examiners. CONCLUSIONS: he results confirm the feasibility of the study protocol by non-dental personnel and its successful integration into the GNC's overall assessment program. However, rigorous dental support of the study centres is required for quality management
Messung der körperlichen Fitness in der NAKO Gesundheitsstudie: Methoden, QualitÀtssicherung und erste deskriptive Ergebnisse
Die körperliche Fitness ist das MaĂ fĂŒr die individuelle FĂ€higkeit, körperlich aktiv zu sein. Ihre wesentlichen Komponenten sind die kardiorespiratorische Fitness (Cardiorespiratory Fitness, CRF), die Muskelkraft und die Beweglichkeit. Neben der körperlichen AktivitĂ€t ist die körperliche Fitness ein wesentlicher PrĂ€diktor fĂŒr MorbiditĂ€t und MortalitĂ€t. Ziel der Arbeit sind die Beschreibung der Erhebungsmethoden körperlicher Fitness in der NAKO Gesundheitsstudie und die Darstellung erster deskriptiver Ergebnisse. In der NAKO-Basiserhebung wurden die maximale Handgreifkraft (Grip Strength, GS) und die CRF als Komponenten der körperlichen Fitness ĂŒber ein Handdynamometer bzw. ĂŒber einen Fahrradergometertest mit submaximaler Belastung erhoben. Daraus wurde die maximale Sauerstoffaufnahme (VO2max) zur Beurteilung der CRF abgeleitet. Die Ergebnisse von insgesamt 99.068 GS-Messungen und 3094 Messungen der CRF beruhen auf einem Datensatz zur Halbzeit der Basiserhebung der NAKO (Alter 20â73 Jahre, 47âŻ% MĂ€nner). MĂ€nner zeigten im Vergleich zu Frauen höhere Werte der körperlichen Fitness (MĂ€nner: GSâŻ=â47,8âŻkg, VO2maxâŻ=â36,4âŻml·minâ1âŻÂ·âkgâ1; Frauen: GSâŻ=â29,9âŻkg, VO2maxâŻ=â32,3âŻml·minâ1âŻÂ·âkgâ1). UngefĂ€hr ab dem 50. Lebensjahr konnte ein RĂŒckgang der GS verzeichnet werden, wohingegen die CRF ab der Altersgruppe 20â29 Jahre bis zu den â„60-JĂ€hrigen kontinuierlich abfiel. Die GS und die VO2max zeigten nach Korrektur fĂŒr das Körpergewicht einen linear positiven Zusammenhang (MĂ€nner ÎČâŻ=â0,21; Frauen ÎČâŻ=â0,35). Die Analysen zeigten eine gute Ăbereinstimmung der Verteilung der körperlichen Fitness in der NAKO im Vergleich zu anderen bevölkerungsbasierten Studien. ZukĂŒnftige Auswertungen werden insbesondere die unabhĂ€ngige Bedeutung der GS und CRF bei der PrĂ€diktion von MorbiditĂ€t und MortalitĂ€t beleuchten.Physical fitness is defined as an individualâs ability to be physically active. The main components are cardiorespiratory fitness (CRF), muscle strength, and flexibility. Regardless of physical activity level, physical fitness is an important determinant of morbidity and mortality. The aim of the current study was to describe the physical fitness assessment methodology in the German National Cohort (NAKO) and to present initial descriptive results in a subsample of the cohort. In the NAKO, hand grip strength (GS) and CRF as physical fitness components were assessed at baseline using a hand dynamometer and a submaximal bicycle ergometer test, respectively. Maximum oxygen uptake (VO2max) was estimated as a result of the bicycle ergometer test. The results of a total of 99,068 GS measurements and 3094 CRF measurements are based on a data set at halftime of the NAKO baseline survey (age 20â73 years, 47% men). Males showed higher values of physical fitness compared to women (males: GSâŻ=â47.8âŻkg, VO2maxâŻ=â36.4âŻml·minâ1âŻÂ·âkgâ1; females: GSâŻ=â29.9âŻkg, VO2maxâŻ=â32.3âŻmlâŻÂ·âminâ1âŻÂ·âkgâ1). GS declined from the age of 50 onwards, whereas VO2max levels decreased continuously between the age groups of 20â29 and â„60 years. GS and VO2max showed a linear positive association after adjustment for body weight (males ÎČâŻ=â0.21; females ÎČâŻ=â0.35). These results indicate that the physical fitness measured in the NAKO are comparable to other population-based studies. Future analyses in this study will focus on examining the independent relations of GS and CRF with risk of morbidity and mortality
Die Basiserhebung der NAKO Gesundheitsstudie: Teilnahme an den Untersuchungsmodulen, QualitÀtssicherung und Nutzung von SekundÀrdaten
BACKGROUND: The German National Cohort (NAKO) is an interdisciplinary health study aimed at elucidating causes for common chronic diseases and detecting their preclinical stages. This article provides an overview of design, methods, participation in the examinations, and their quality assurance based on the midterm baseline dataset (MBD) of the recruitment. METHODS: More than 200,000 women and men aged 20â69 years derived from random samples of the German general population were recruited in 18 study centers (2014â2019). The data collection comprised physical examinations, standardized interviews and questionnaires, and the collection of biomedical samples for all participants (level 1). At least 20% of all participants received additional in-depth examinations (level 2), and 30,000 received whole-body magnet resonance imaging (MRI). Additional information will be collected through secondary data sources such as medical registries, health insurances, and pension funds. This overview is based on the MBD, which included 101,839 participants, of whom 11,371 received an MRI. RESULTS: The mean response proportion was 18%. The participation in the examinations was high with most of the modules performed by over 95%. Among MRI participants, 96% completed all 12 MRI sequences. More than 90% of the participants agreed to the use of complementary secondary and registry data. DISCUSSION: Individuals selected for the NAKO were willing to participate in all examinations despite the time-consuming program. The NAKO provides a central resource for population-based epidemiologic research and will contribute to developing innovative strategies for prevention, screening and prediction of chronic diseases.HINTERGRUND: Die NAKO Gesundheitsstudie ist ein bundesweites interdisziplinĂ€res Forschungsvorhaben mit dem Ziel, die Ursachen fĂŒr chronische Krankheiten und deren vorklinische Stadien zu untersuchen. Der Artikel gibt einen Ăberblick ĂŒber das Studiendesign, die Methoden, die Teilnahme an den Untersuchungen und ihre QualitĂ€tssicherung zur Halbzeit der Basiserhebung.
METHODEN: FĂŒr die Basiserhebung wurden mehr als 200.000 Frauen und MĂ€nner im Alter von 20â69 Jahren aus Zufallsstichproben der Allgemeinbevölkerung in 18 Studienzentren rekrutiert (2014â2019). Die Basiserhebung beinhaltet Untersuchungen, Befragungen und Biomaterialien fĂŒr alle Teilnehmerinnen und Teilnehmer (Level 1), ein erweitertes Programm fĂŒr mindestens 20âŻ% (Level 2) und eine Magnetresonanztomografie (MRT) fĂŒr 30.000 Teilnehmerinnen und Teilnehmer. SekundĂ€r- und Registerdaten werden ĂŒber Krankheitsregister, Kranken- und Rentenversicherungen erhoben. Die Auswertung bezieht die Datenbasis zur Halbzeit der Basiserhebung mit 101.839 Teilnehmerinnen und Teilnehmern ein, davon 11.371 mit einer MRT-Untersuchung. ERGEBNISSE: Die mittlere Responsequote zur Halbzeit betrug insgesamt 18âŻ%. Die Teilnahme an den Untersuchungen lag ĂŒberwiegend bei mehr als 95âŻ%. Bei 96âŻ% der MRT-Teilnehmerinnen und Teilnehmer konnten alle 12 MRT-Sequenzen vollstĂ€ndig durchgefĂŒhrt werden. Der ErschlieĂung und wissenschaftlichen Nutzung ergĂ€nzender SekundĂ€r- und Registerdaten stimmten mehr als 90âŻ% der Teilnehmerinnen und Teilnehmer zu. DISKUSSION: Die Bereitschaft, möglichst alle Untersuchungsmodule durchzufĂŒhren, war trotz des zeitlichen Aufwandes auĂerordentlich hoch. Dadurch wird die NAKO zu einer zentralen Ressource fĂŒr die epidemiologische Forschung in Deutschland. Sie wird es ermöglichen, neue Strategien zur FrĂŒherkennung, Vorhersage und PrimĂ€rprĂ€vention chronischer Krankheiten zu entwickeln
- âŠ