Indirect Estimation of Link Delays by Directly Observing a Triplet of Network Metrics

AbstractThis paper presents an improved indirect estimation link delays from a triplet of network metrics; path delays, packet loss rate (PLR), and jitter by using indirect inverse modeling techniques. conventionally a network metric is estimated by directly observing another network parameter. Based on the evidence in the literature that path delays, PLR, and jitter are interdependent, this work exploits this mutual interdependent of this triplet of metrics based on the notion that a better observation leads to better estimation. We applied NTF1 model, a variation of non negative tensor factorization (NTF) for this purpose and estimated link delay from a triplet of metrics. Evaluation process used data from an experimental test bed that consists of standard networking devices. The estimated link delays were correlated to actual link delays to benchmark the accuracy of estimation. Results showed a better correlation between the estimated and measured link delays when a triplet of metrics is used

Roadmap on measurement technologies for next generation structural health monitoring systems

Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots

Roadmap on measurement technologies for next generation structural health monitoring systems

Structural health monitoring (SHM) is the automation of the condition assessment process of an engineered system. When applied to geometrically large components or structures, such as those found in civil and aerospace infrastructure and systems, a critical challenge is in designing the sensing solution that could yield actionable information. This is a difficult task to conduct cost-effectively, because of the large surfaces under consideration and the localized nature of typical defects and damages. There have been significant research efforts in empowering conventional measurement technologies for applications to SHM in order to improve performance of the condition assessment process. Yet, the field implementation of these SHM solutions is still in its infancy, attributable to various economic and technical challenges. The objective of this Roadmap publication is to discuss modern measurement technologies that were developed for SHM purposes, along with their associated challenges and opportunities, and to provide a path to research and development efforts that could yield impactful field applications. The Roadmap is organized into four sections: distributed embedded sensing systems, distributed surface sensing systems, multifunctional materials, and remote sensing. Recognizing that many measurement technologies may overlap between sections, we define distributed sensing solutions as those that involve or imply the utilization of numbers of sensors geometrically organized within (embedded) or over (surface) the monitored component or system. Multi-functional materials are sensing solutions that combine multiple capabilities, for example those also serving structural functions. Remote sensing are solutions that are contactless, for example cell phones, drones, and satellites. It also includes the notion of remotely controlled robots

Pattern Of Reduced Functional Connectivity And Structural Abnormalities In Parkinson's Disease: An Exploratory Study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)MRI brain changes in Parkinson's disease (PD) are controversial. Objectives: We aimed to describe structural and functional changes in PD. Methods: Sixty-six patients with PD (57.94 +/- 10.25 years) diagnosed according to the UK Brain Bank criteria were included. We performed a whole brain analysis using voxel-based morphometry (VBM-SPM 8 software), cortical thickness (CT) using CIVET, and resting-state fMRI using the Neuroimaging Analysis Kit software to compare patients and controls. For VBM and CT we classified subjects into three groups according to disease severity: mild PD [Hoehn and Yahr scale (HY) 1-1.5], moderate PD (HY 2-2.5), and severe PD (HY 3-5). Results: We observed gray matter atrophy in the insula and inferior frontal gyrus in the moderate PD and in the insula, frontal gyrus, putamen, cingulated, and paracingulate gyri in the severe groups. In the CT analysis, in mild PD, cortical thinning was restricted to the superior temporal gyrus, gyrus rectus, and olfactory cortex; in the moderate group, the postcentral gyrus, supplementary motor area, and inferior frontal gyrus were also affected; in the severe PD, areas such as the precentral and postentral gyrus, temporal pole, fusiform, and occipital gyrus had reduced cortical thinning. We observed altered connectivity at the default mode, visual, sensorimotor, and cerebellar networks. Conclusion: Subjects with mild symptoms already have cortical involvement; however, further cerebral involvement seems to follow Braak's proposed mechanism. Similar regions are affected both structurally and functionally. We believe the combination of different MRI techniques may be useful in evaluating progressive brain involvement and they may eventually be used as surrogate markers of disease progression.7FAPESP (Sao Paulo Research Foundation) [2012/05286-7, 2011/19958-4, 2013/03358-3]CNPq [74873/2010-2]FAPESPIpsenCNPq, BRAZILFAPESP, BRAZILFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Pentacam® Corneal Tomography for Screening of Refractive Surgery Candidates: A Review of the Literature, Part I

Corneal tomography and Scheimpflug imaging are frequently used to analyze the corneal surface, especially in the field of cataract and refractive surgery. The Pentacam system is one of the most commonly used commercially available systems for this purpose. Through a rotating Scheimpflug camera, the system is capable of creating a three-dimensional map of the cornea. These advances in tomography have simultaneously enhanced the ability of clinicians to screen surgical candidates and detect subtle corneal changes in diseases such as keratoconus. However, there remains a need to enhance diagnosis in order to recognize mild and early forms of corneal ectasia. As iatrogenic ectasia and keratoconus are dreaded complications of refractive surgery, it is imperative to screen patients appropriately prior to surgery. The Pentacam is one of many systems utilized in the screening process, but the literature has not identified specific protocol nor parameters that are capable of carrying out this process appropriately. Post-operative keratoconus continues to occur despite the advances in technology seen in corneal imaging. Therefore, clear indices for screening are required in order to diagnose early forms of keratoconus and other corneal diseases that may exclude the seemingly asymptomatic patient from undergoing refractive surgery. This article aims to summarize the indices available on the Pentacam system and to identify the most accurate parameters for screening of the refractive surgery candidate

Review of the indexes to assess the ecological quality of coralligenous reefs: towards a unified approach

There is an urgent need to better understand the stressors, namely heatwaves, changes in thermohaline circulation and mucilage events, that are rapidly reshaping bioconstructions, such as coralligenous assemblages. This calls for increased monitoring efforts in these invaluable habitats that will improve our understanding of the resistance and resilience of bioconstructions. Since 2009, 16 indexes have been designed to assess the ecological quality of Mediterranean coralligenous reefs. The main objective of this work is to propose a framework to support the development of a shared, cost-effective, and practical index to assess the status of the coralligenous biocenosis. To achieve this, studies conceiving these 16 indexes were reviewed: comparing their objectives, metrics, and applied methodologies. A standardized nomenclature of anthropogenic pressures is supplied, using, when possible, definitions from the European Habitat Directive, Marine Strategy Framework Directive and Water Framework Directive. Additionally, given the unprecedented climatic conditions, we highlight that a common index should give particular attention to the response of the coralligenous to thermal stress and mucilage. A list of priority anthropogenic pressures/environmental stressors and relative indicators and metrics are suggested. This review stresses the urgency to align the methodologies at basin scale and highlights the pros and cons of the preexisting indexes that must be considered in the design of a new, shared procedure to evaluate the status of coralligenous assemblages

Benthic diatom monitoring and assessment of freshwater environments: standard methods and future challenges

Fil: Soizic, Morin. National Research Institute of Science and Technology for Environment and Agriculture; FranceFil: Gómez, Nora. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Tornés, Elisabet. University of Girona. Institute of Aquatic Ecology; SpainFil: Licursi, Magdalena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología Dr. Raúl A. Ringuelet; ArgentinaFil: Rosebery, Juliette. Aquatic Ecosystems and Global Changes Research Unit; Franc

Transepithelial accelerated corneal collagen crosslinking in patients with progressive keratoconus: long term follow up results

Objetivo: avaliar de forma sistematizada a eficácia a longo prazo do crosslinking de colagénio corneano transepitelial acelerado (TE-ACXL) no tratamento de olhos com queratocone progressivo, reportando os seus outcomes visuais e morfológicos ao longo de um follow-up de 4 anos. Métodos: olhos de pacientes submetidos a TE-ACXL (6mW/cm2 durante 15 minutos) para queratocone progressivo foram incluídos neste estudo de coorte retrospetivo. Melhor acuidade visual corrigida (BCVA), valores queratométricos, paquimetria corneana mínima (PachyMin) e índices topográficos foram analisados pré-operatoriamente e a cada 6 meses após o TE-ACXL, até um máximo de 48 meses. A progressão da doença foi definida como um aumento ≥ 1.00 D do astigmatismo corneano, um aumento ≥ 1.00 D da queratometria máxima (Kmax), uma redução ≥ 2% da PachyMin ou um aumento ≥ 0.42 unidades do D-index. Resultados: o estudo envolveu 39 olhos de 30 pacientes. Não foram observadas diferenças estatisticamente significativas na BCVA, astigmatismo corneano, Kmax, índice de variação da superfície corneana (ISV), índice de descentralização por elevação da córnea (IHD) e índice queratocone (KI) entre a avaliação de base e as avaliações subsequentes (p>0.05). Houve um aumento significativo aos 12, 24 e 36 meses de seguimento na queratometria média (Km) (0.66 ± 1.07 D, p=0.001; 0.94 ± 1,42 D, p=0.001; 1.48 ± 1.19 D, p=0.002) e D-index (0.50 ± 1.05 unidades, p=0.011; 0.53 ± 1.19 unidades, p=0.024; 1.29 ± 1.11 unidades, p=0.003). Houve uma redução estatisticamente significativa na PachyMin aos 36 meses (-10.45 ± 15.20 µm, p=0.046) e no índice de assimetria vertical da córnea (IVA) aos 24 meses (-0.07 ± 0.16 unidades, p=0.024). 28 (71.8%) olhos mantiveram progressão por pelo menos um critério. 2 (5.1%) olhos cumpriram os 4 critérios de progressão definidos. Não foram registadas complicações durante a cirurgia ou seguimento em nenhum dos doentes. Conclusão: o TE-ACXL parece ser um tratamento seguro e eficaz no tratamento do queratocone progressivo. Recomenda-se a definição de novos critérios de progressão específicos e significativos e estudos prospetivos adicionais com coortes mais alargados.Purpose: to systematically evaluate the long-term efficacy of transepithelial accelerated corneal collagen crosslinking (TE-ACXL) in the treatment of eyes with progressive keratoconus by reporting its visual and morphological outcomes throughout a 4-year follow-up. Methods: eyes of patients who underwent TE-ACXL (6mW/cm2 for 15 minutes) for progressive keratoconus were included in this retrospective cohort study. Best-corrected visual acuity (BCVA), keratometry measurements, thinnest corneal thickness (PachyMin), and topographic indexes were analyzed preoperatively and every 6 months after TE-ACXL, up to a maximum of 48 months. Disease progression was defined as an increase ≥ 1.00 D in corneal astigmatism, an increase ≥ 1.00 D in maximum keratometry (Kmax), a decrease ≥ 2% in PachyMin, or an increase ≥ 0.42 units in D-index. Results: the study enrolled 39 eyes from 30 patients. No significant differences were observed in BCVA, corneal astigmatism, Kmax, index of surface variance (ISV), index of height decentration (IHD), and keratoconus index (KI) between baseline and subsequent follow-up evaluations (p>0.05). There was a significant increase at 12-, 24- and 36-months follow-up in mean keratometry (Km) (0.66 ± 1.07 D, p=0.001; 0.94 ± 1,42 D, p=0.001; 1.48 ± 1.19 D, p=0.002) and D-index (0.50 ± 1.05 units, p=0.011; 0.53 ± 1.19 units, p=0.024; 1.29 ± 1.11 units, p=0.003). There were significant decreases in PachyMin at 36 months (-10.45 ± 15.20 µm, p=0.046) and in index of vertical asymmetry (IVA) at 24 months (-0.07 ± 0.16 units, p=0.024). 28 (71.8%) eyes maintained progression by at least one criterion. 2 (5.1%) eyes fulfilled all 4 progression criteria. Surgery and follow-up were uneventful in all subjects. Conclusion: TE-ACXL seems to be a safe and effective treatment for progressive keratoconus. Definition of new specific and significant progression criteria and further prospective studies with larger cohorts are recommended

Soft tissue radiodensity parameters mediate the relationship between self-reported physical activity and lower extremity function in AGES-Reykjavík participants.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadAlthough previous studies have highlighted the association between physical activity and lower extremity function (LEF) in elderly individuals, the mechanisms underlying this relationship remain debated. Our recent work has recognized the utility of nonlinear trimodal regression analysis (NTRA) parameters in characterizing changes in soft tissue radiodensity as a quantitative construct for sarcopenia in the longitudinal, population-based cohort of the AGES-Reykjavík study. For the present work, we assembled a series of prospective multivariate regression models to interrogate whether NTRA parameters mediate the 5-year longitudinal relationship between physical activity and LEF in AGES-Reykjavík participants. Healthy elderly volunteers from the AGES-Reykjavík cohort underwent mid-thigh X-ray CT scans along with a four-part battery of LEF tasks: normal gait speed, fastest-comfortable gait speed, isometric leg strength, and timed up-and-go. These data were recorded at two study timepoints which were separated by approximately 5 years: AGES-I (n = 3157) and AGES-II (n = 3098). Participants in AGES-I were likewise administered a survey to approximate their weekly frequency of engaging in moderate-to-vigorous physical activity (PAAGES-I). Using a multivariate mediation analysis framework, linear regression models were assembled to test whether NTRA parameters mediated the longitudinal relationship between PAAGES-I and LEFAGES-II; all models were covariate-adjusted for age, sex, BMI, and baseline LEF, and results were corrected for multiple statistical comparisons. Our first series of models confirmed that all four LEF tasks were significantly related to PAAGES-I; next, modelling the relationship between PAAGES-I and NTRAAGES-II identified muscle amplitude (Nm) and location (μm) as potential mediators of LEF to test. Finally, adding these two parameters into our PAAGES-I → LEFAGES-II models attenuated the prior effect of PAAGES-I; bootstrapping confirmed Nm and μm as significant partial mediators of the PAAGES-I → LEFAGES-II relationship, with the strongest effect found in isometric leg strength. This work describes a novel approach toward clarifying the mechanisms that underly the relationship between physical activity and LEF in aging individuals. Identifying Nm and μm as significant partial mediators of this relationship provides strong evidence that physical activity protects aging mobility through the preservation of both lean tissue quantity and quality.United States Department of Health & Human Services National Institutes of Health (NIH) - USA NIH National Institute on Aging (NIA