Amostragem multi-adaptativa de tráfego de rede

http://crc2011.uc.pt/A monitorização eficiente de redes e serviços tem um papel crucial no suporte à gestão e engenharia das redes de comunicações atuais. Obter uma visão realista do estado da rede sem, no entanto, interferir na sua operação normal é essencial no suporte à decisão dos operadores de redes e dos sistemas auto-configuráveis. Neste sentido, as técnicas de amostragem de tráfego procuram reduzir o impacto da monitorização no funcionamento da rede, mantendo a acurácia na estimação de parâmetros referentes ao seu comportamento estatístico. Embora seja observada uma evolução das atuais técnicas na correta estimação do desempenho da rede, o overhead associado ao volume de dados envolvidos nos processos de amostragem de tráfego ainda é considerável. Neste contexto, este trabalho propõe uma nova técnica de amostragem multi-adaptativa de tráfego, baseada em predição linear, que tem por objetivo reduzir significativamente o volume total de dados envolvidos na monitorização do estado da rede, sem comprometer a representatividade das amostras na estimação dos parâmetros em análise. A avaliação desta proposta, com base em coletas de tráfego real, demonstra que é possível reduzir significativamente o volume de dados analisado e mesmo assim alcançar, em vários parâmetros de caracterização, resultados mais precisos que as técnicas classicamente utilizadas

Data security and trustworthiness in online public services: An assessment of Portuguese institutions

Providing public services through the internet is an effective approach towards an encompassing number of citizens being covered by them and for cost reduction. However, the fast development of this area has fostered discussion and legislation regarding information security and trustworthiness. In addition to security mechanisms for data processed and stored internally, service providers must ensure that data exchanged between their servers and citizens are not intercepted or modified when traversing heterogeneous and uncontrolled networks. Moreover, such institutions should provide means enabling the citizen to verify the authenticity of the services offered. In this way, the present work provides a comprehensive overview regarding the security posture of Portuguese public institutions in their online services. It consists of non-invasive robustness evaluation of the deployed solutions for end-to-end data encryption and the correct use of digital certificates. As a result, we provide some recommendations aiming to enhance the current panorama in the majority of the 111 online services considered in this study.This paper is a result of the project SmartEGOV: Harnessing EGOV for Smart Governance (Foundations, Methods, Tools) NORTE-01-0145-FEDER-000037, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (EFDR)

Enhancing traffic sampling scope and efficiency

Traffic Sampling is a crucial step towards scalable network measurements, enclosing manifold challenges. The wide variety of foreseeable sampling scenarios demands for a modular view of sampling components and features, grounded on a consistent architecture. Articulating the measurement scope, the required information model and the adequate sampling strategy is a major design issue for achieving an encompassing and efficient sampling solution. This is the main focus of the present work, where a layered architecture, a taxonomy of existing sampling techniques distinguishing their inner characteristics and a flexible framework able to combine these characteristics are introduced. In addition, a new multiadaptive technique proposal, based on linear prediction, allows to reduce the measurement overhead significantly, while assuring that traffic samples reflect the statistical behavior of the global traffic under analysis.Fundação para a Ciência e a Tecnologia (FCT

A multiadaptive sampling technique for cost-effective network measurements

The deployment of efficient measurement solutions to assist network management tasks without interfering with normal network operation assumes a prominent role in today’s high-speed networks attending to the huge amounts of traffic involved. From a myriad of proposals for traffic measurement, sampling techniques are particularly relevant contributing effectively for this purpose as only a subset of the overall traffic volume is handled for processing, preserving ideally the correct estimation of network statistical behavior. In this context, this paper proposes MuST – a multiadaptive sampling technique based on linear prediction, aiming at reducing significantly the measurement overhead and still assuring that traffic samples reflect the statistical characteristics of the global network traffic under analysis. Conversely to current sampling techniques, MuST is a multi and self-adaptive technique as both the sample size and interval between samples are self-adjustable parameters according to the ongoing network activity and the accuracy of prediction achieved. The tests carried out demonstrate that the proposed sampling technique is able to achieve accurate network estimations with reduced overhead, using throughput as reference parameter. The evaluation results, obtained resorting to real traffic traces representing wired and wireless aggregated traffic scenarios and actual network services, prove that the simplicity, flexibility and self-adaptability of the proposed technique can be successfully explored to improve network measurements efficiency over distinct traffic conditions. For optimization purposes, this paper also includes a study of the impact of varying the order of prediction, i.e., of considering different degrees of past memory in the self-adaptive estimation mechanism. The significance of the obtained results is demonstrated through statistical benchmarking.Fundação para a Ciência e a Tecnologia (FCT

Vocal repertoire of Scinax v-signatus (Lutz 1968) (Anura, Hylidae) and comments on bioacoustical synapomorphies for Scinax perpusillus species group

Herein we describe the vocal repertoire of Scinax v-signatus, compare it to the other species belonging to the S. perpusillus species group and discuss the bioacoustical synapomorphies proposed for the group. We recorded an advertisement call and an aggressive call of S. v-signatus. The advertisement call is similar to the one described for others species of the Scinax perpusillus group. Similarly to Scinax cosenzai, the first note in the advertisement call of S. v-signatus is the longest. The aggressive call was preceded by a series of advertisement calls. We suggest that bioacoustical parameters proposed as synapomorphies for the Scinax perpusillus group are not valid, as they are also observed in species belonging to other groups within the genus

Effects of Propranolol on Growth, Lipids and Energy Metabolism and Oxidative Stress Response of Phaeodactylum tricornutum

Present demographic trends suggest a rise in the contributions of human pharmaceuticals into coastal ecosystems, underpinning an increasing demand to evaluate the ecotoxicological effects and implications of drug residues in marine risk assessments. Propranolol, a non-selective β-adrenoceptor blocker, is used worldwide to treat high blood pressure conditions and other related cardiovascular conditions. Although diatoms lack β-adrenoceptors, this microalgal group presents receptor-like kinases and proteins with a functional analogy to the animal receptors and that can be targeted by propranolol. In the present work, the authors evaluated the effect of this non-selective β-adrenoceptor blocker in diatom cells using P. tricornutum as a model organism, to evaluate the potential effect of this compound in cell physiology (growth, lipids and energy metabolism and oxidative stress) and its potential relevance for marine ecosystems. Propranolol exposure leads to a significant reduction in diatom cell growth, more evident in the highest concentrations tested. This is likely due to the observed impairment of the main primary photochemistry processes and the enhancement of the mitochondrial respiratory activity. More specifically, propranolol decreased the energy transduction from photosystem II (PSII) to the electron transport chain, leading to an increase in oxidative stress levels. Cells exposed to propranolol also exhibited high-dissipated energy flux, indicating that this excessive energy is efficiently diverted, to some extent, from the photosystems, acting to prevent irreversible photoinhibition. As energy production is impaired at the PSII donor side, preventing energy production through the electron transport chain, diatoms appear to be consuming storage lipids as an energy backup system, to maintain essential cellular functions. This consumption will be attained by an increase in respiratory activity. Considering the primary oxygen production and consumption pathways, propranolol showed a significant reduction of the autotrophic O2 production and an increase in the heterotrophic mitochondrial respiration. Both mechanisms can have negative effects on marine trophic webs, due to a decrease in the energetic input from marine primary producers and a simultaneous oxygen production decrease for heterotrophic species. In ecotoxicological terms, bio-optical and fatty acid data appear as highly efficient tools for ecotoxicity assessment, with an overall high degree of classification when these traits are used to build a toxicological profile, instead of individually assessed.info:eu-repo/semantics/publishedVersio

Investigating Early/Middle Bronze Age Copper and Bronze Axes by Micro X-Ray Fluorescence Spectrometry and Neutron Imaging Techniques

Micro X-ray fluorescence (micro-XRF) analysis and neutron imaging techniques, namely 2D radiography and 3D tomography, have been applied for the study of four metal axes from the Early/Middle Bronze Age in Western Iberia, a period characterized by a metallurgical change in the use of copper to bronze. Micro-XRF analysis has shown that one of the axes was produced in copper with some arsenic while the other three were produced in a copper-tin alloy (bronze) with variable tin contents and some arsenic and lead. Neutron radiography and tomographywere applied to study internal heterogeneities of the axes in a non-invasiveway since the specificities of neutron interaction with matter allow a suitable penetration of these relatively thick copper-based objects when compared to the use of a conventional X-ray radiography. Neutron imaging allowed the visualization of internal fissures and pores and the evaluation of their distribution, size and shape. Relevant information for the reconstruction of ancient manufacturing techniques was gathered, revealing that one ax was produced with the mold in an angle of ≈25°, probably to facilitate gas escape during metal pouring. Also, information regarding physical weaknesses of the axes was collected, providing relevant data for their conservation. Novelty statement: The present paper combines the use of micro-XRF and neutron imaging techniques, namely (2D) radiography and (3D) tomography for the study of prehistoric metal axes. The XRF spectra allowed identifying major and minor elements present in the alloys, inferring on the absence of elements that could become radioactive for a long period of time after irradiation with neutrons. The specificities of neutron interaction with matter allowed a suitable penetration of these relatively thick copper-based objects when compared to the use of a conventional X-ray radiography. The combination of these non-destructive techniques allowed the evaluation of the metal composition and the internal structure of the axes. Micro-XRF allowed the distinction among copper and bronze axes, and provided data about the composition of early bronzes for which data is scarce. The neutron imaging study allowed for the first timethe visualization of internal heterogeneities in early bronze axes, namely pores and large voids, providing relevant information for the reconstruction of ancient manufacturing techniques and raising pertinent information regarding physical weaknesses of these types of objects.info:eu-repo/semantics/publishedVersio

Geometric analysis of female pelvic floor muscles by using manual segmentation

Magnetic Resonance Imaging (MRI) has been used in the diagnostic evaluation of the pelvic floor dysfunctions. MRI can contribute to generate 3D solids of pelvic floor muscles through manual segmentation. The aim of this study is to calculate the area and its moment of inertia of 8 female pelvic floor muscles by using manual segmentation technique. Based on CAD software manual segmentation was used. To build 3D reconstruction models, through of twenty consecutive images. The models were made through splines in each sketch, documenting changes in the pubovisceral muscle (a part from the pelvic floor muscles) from the pubis to coccyx. Two sketches were chosen and biomechanics properties like area and stiffness (moment of inertia) were acquired for each sketch used to generate the pubovisceral muscles. The moment of inertia of the pubovisceral muscle decreases following the order: anterior sketch and posterior sketch. Higher values for the moment of inertia can be encountered in anterior sketcher. This conclusion can lead to more stability in the anterior compartment of pelvic floor visceral