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See detailDevelopment and evaluation of injectable nanosized drug delivery systems for apigenin
Karim, Reatul ULiege; Palazzo, Claudio ULiege; Laloy, Julie et al

in International Journal of Pharmaceutics (2017), 532(2), 757-768

The purpose of this study was to develop different injectable nanosized drug delivery systems (NDDSs) i.e. liposome, lipid nanocapsule (LNC) and polymeric nanocapsule (PNC) encapsulating apigenin (AG) and ... [more ▼]

The purpose of this study was to develop different injectable nanosized drug delivery systems (NDDSs) i.e. liposome, lipid nanocapsule (LNC) and polymeric nanocapsule (PNC) encapsulating apigenin (AG) and compare their characteristics to identify the nanovector(s) that can deliver the largest quantity of AG while being biocompatible. Two liposomes with different surface characteristics (cationic and anionic), a LNC and a PNC were prepared. A novel tocopherol modified poly(ethylene glycol)-b-polyphosphate block-copolymer was used for the first time for the PNC preparation. The NDDSs were compared by their physicochemical characteristics, AG release, storage stability, stability in serum, complement consumption and toxicity against a human macrovascular endothelial cell line (EAhy926). The diameter and surface charge of the NDDSs were comparable with previously reported injectable nanocarriers. The NDDSs showed good encapsulation efficiency and drug loading. Moreover, the NDDSs were stable during storage and in fetal bovine serum for extended periods, showed low complement consumption and were non-toxic to EAhy926 cells up to high concentrations. Therefore, they can be considered as potential injectable nanocarriers of AG. Due to less pronounced burst effect and extended release characteristics, the nanocapsules could be favorable approaches for achieving prolonged pharmacological activity of AG using injectable NDDS. [less ▲]

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See detailIncreasing plant functional diversity is not the key for supporting pollinators in wildflower strips
Uyttenbroeck, Roel ULiege; Piqueray, Julien; Hatt, Séverin ULiege et al

in Agriculture, Ecosystems & Environment (2017), 249

Intensification of agriculture has been one of the major drivers for biodiversity loss in recent decades. Pollinators, which serve an important role in pollinating crops as well as wild plants, have shown ... [more ▼]

Intensification of agriculture has been one of the major drivers for biodiversity loss in recent decades. Pollinators, which serve an important role in pollinating crops as well as wild plants, have shown a decline in species richness. Flower strips can be used to support pollinators in agro-ecosystems, however the question remains as to how their design can be optimized in order to best benefit pollinators. Increasing plant species diversity has been shown to be beneficial for pollinators, and it is often suggested that functional traits are driving this relationship. Therefore, increasing plant functional diversity could be a tool to support pollinator abundance and diversity. As experimental evidence on this relationship is scarce, we developed a field study with experimental sown flower strips with four functional diversity levels, based on multiple flower traits and with equal plant species richness. We monitored vegetation development, as well as the flower-visiting pollinator community and their interaction networks with flowers. We were able to create a functional diversity gradient while controlling for plant species richness and evenness. However, in contrast to our expectations, pollinator species richness and evenness were not influenced by functional diversity, and increasing functional diversity even resulted in lower flower visitation rates. Network stability metrics showed no effect or negative relationships with functional diversity. We conclude that increasing functional diversity was not the key for supporting pollinators in wildflower strips. Our results also suggest that, for a constant amount of flower resources, increasing plant functional diversity and thus decreasing redundancy of potential pollinator feeding niches, decreases the amount of flower resources present per feeding niche. As pollinator species tended to have less overlap in their feeding niches in flower strips with increased functional diversity, this may lead to a reduction of flower resources available for pollinator species with a more specialized feeding niche. [less ▲]

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See detailImproving fungal disease forecasts in winter wheat: A critical role of intra-day variations of meteorological conditions in the development of Septoria leaf blotch
El Jarroudi, Moussa ULiege; kOUADIO, Louis; EL JARROUDI, Mustapha et al

in Field Crops Research (2017), 213

Meteorological conditions are important factors in the development of fungal diseases in winter wheat and are the main inputs of the decision support systems used to forecast disease and thus determine ... [more ▼]

Meteorological conditions are important factors in the development of fungal diseases in winter wheat and are the main inputs of the decision support systems used to forecast disease and thus determine timing for efficacious fungicide application. This study uses the Fourier transform method (FTM) to characterize temporal patterns of meteorological conditions between two neighbouring experimental sites used in a regional fungal disease monitoring and forecasting experiment in Luxembourg. Three meteorological variables (air temperature, relative humidity, and precipitation) were included, all conducive to infection of wheat by Zymoseptoria tritici cause of Septoria leaf blotch (STB) in winter wheat, from 2006 to 2009. The intraday, diurnal, dekadal and intra-seasonal variations of the meteorological variables were assessed using FTM, and the impact of existing contrasts between sites on the development of STB was analyzed. Although STB severities varied between sites and years (P ≤ 0.0003), the results indicated that the two sites presented the same patterns of meteorological conditions when compared at larger temporal scales (diurnal to intra-seasonal scales, with time periods >11 h). However, the intraday variations of all the variables were well discriminated between the sites and were highly correlated to STB severities. Our findings highlight and confirm the importance of intraday meteorological variation in the development of STB in winter wheat fields. Furthermore, the FTM approach has potential for identifying microclimatic conditions prevailing at given sites and could help in improving the prediction of disease forecast models used in regional warning systems. [less ▲]

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See detailH0LiCOW VII: cosmic evolution of the correlation between black hole mass and host galaxy luminosity
Ding, Xuheng; Treu, Tommaso; Suyu, Sherry H. et al

in Monthly Notices of the Royal Astronomical Society (2017), 472

Strongly lensed active galactic nuclei (AGN) provide a unique opportunity to make progress in the study of the evolution of the correlation between the mass of supermassive black holes (M_BH) and their ... [more ▼]

Strongly lensed active galactic nuclei (AGN) provide a unique opportunity to make progress in the study of the evolution of the correlation between the mass of supermassive black holes (M_BH) and their host galaxy luminosity (L[SUB]host[/SUB]). We demonstrate the power of lensing by analysing two systems for which state-of-the-art lens modelling techniques have been applied to deep Hubble Space Telescope imaging data. We use (i) the reconstructed images to infer the total and bulge luminosity of the host and (ii) published broad-line spectroscopy to estimate M_BH using the so-called virial method. We then enlarge our sample with new calibration of previously published measurements to study the evolution of the correlation out to z ˜ 4.5. Consistent with previous work, we find that without taking into account passive luminosity evolution, the data points lie on the local relation. Once the passive luminosity evolution is taken into account, we find that black holes in the more distant Universe reside in less luminous galaxies than today. Fitting this offset as M_BH/L[SUB]host[/SUB] ∝ (1 + z)[SUP]γ[/SUP], and taking into account selection effects, we obtain γ = 0.6 ± 0.1 and 0.8 ± 0.1 for the case of M_BH-L[SUB]bulge[/SUB] and M_BH-L[SUB]total[/SUB], respectively. To test for systematic uncertainties and selection effects we also consider a reduced sample that is homogeneous in data quality. We find consistent results but with considerably larger uncertainty due to the more limited sample size and redshift coverage (γ = 0.7 ± 0.4 and 0.2 ± 0.5 for M_BH-L[SUB]bulge[/SUB] and M_BH-L[SUB]total[/SUB], respectively), highlighting the need to gather more high-quality data for high-redshift lensed quasar hosts. Our result is consistent with a scenario where the growth of the black hole predates that of the host galaxy. [less ▲]

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See detailA coupled electro-thermal Discontinuous Galerkin method
Homsi, Lina ULiege; Geuzaine, Christophe ULiege; Noels, Ludovic ULiege

in Journal of Computational Physics (2017), 348

This paper presents a Discontinuous Galerkin scheme in order to solve the nonlinear elliptic partial differential equations of coupled electro-thermal problems. In this paper we discuss the fundamental ... [more ▼]

This paper presents a Discontinuous Galerkin scheme in order to solve the nonlinear elliptic partial differential equations of coupled electro-thermal problems. In this paper we discuss the fundamental equations for the transport of electricity and heat, in terms of macroscopic variables such as temperature and electric potential. A fully coupled nonlinear weak formulation for electro-thermal problems is developed based on continuum mechanics equations expressed in terms of energetically conjugated pair of fluxes and fields gradients. The weak form can thus be formulated as a Discontinuous Galerkin method. The existence and uniqueness of the weak form solution are proved. The numerical properties of the nonlinear elliptic problems i.e., consistency and stability, are demonstrated under specific conditions, i.e. use of high enough stabilization parameter and at least quadratic polynomial approximations. Moreover the prior error estimates in the H1-norm and in the L2-norm are shown to be optimal in the mesh size with the polynomial approximation degree. [less ▲]

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See detailTwenty-year tracking of lighting savings and power density in the residential sector
Attia, Shady ULiege; Hamdy, Mohamed; Ezzeldin, Sherif

in Energy and Buildings (2017), 154

Lighting energy consumption represents a significant percentage of total energy consumption in residential building sector. During the last 20 years, advanced energy-efficient lighting fixtures have been ... [more ▼]

Lighting energy consumption represents a significant percentage of total energy consumption in residential building sector. During the last 20 years, advanced energy-efficient lighting fixtures have been introduced worldwide to conserve the energy consumption in residences. In the Middle East and North Africa (MENA) region, very few studies have been conducted to evaluate the association between the introduced lighting fixtures and the resulted energy savings using valid measurements and verification techniques. This study evaluates the techno-economic impact of replacing new energy efficient lighting in residences in Egypt (a representative MENA region country). A quantitative analysis is applied by tracking the utility bills of 150 residential apartments in Cairo. The average measured power consumption before (1993-1998) and after (2009-2014) installation energy efficient lighting fixtures is analyzed. A building performance simulation model is developed to back the findings. The findings indicate a significant disparity between the estimated savings based on simulation and the real measured savings due to penetration, rebound effect and low quality lamps. Moreover, the findings present an example of quantified benefits of energy efficient lighting, which is very important to inform the decision making of public policy makers, investors and building occupants. [less ▲]

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See detailEvaluation of adaptive facades: The case study of Al Bahr Towers in the UAE
Attia, Shady ULiege

in Shaping Qatar’s Sustainable Built Environment (2017), 2(6), 1-13

The assessment of adaptive facades presents a barrier as there is no established assessment technique. Many of the available facade performance evaluation systems or frameworks have limited applicability ... [more ▼]

The assessment of adaptive facades presents a barrier as there is no established assessment technique. Many of the available facade performance evaluation systems or frameworks have limited applicability for such advanced building facades. The complexity of adaptive or dynamic facades’ evaluation is related to the performance evaluation of facade elements, systems, and overall building performance coupled with occupant behavior and occupant satisfaction. In this context, this paper presents a case study of an adaptive sunscreen facade and evaluation of its performance and occupant behavior. The evaluation mainly focuses on pre- and post-construction phases of adaptive facades: the design assist phase (including the durability test, visual mockup, onsite mashrabiya mounting, and weather stripping), the commissioning phase (field verification and performance testing), and the monitoring phase. The selected project is a 150-meter-high twin tower that stands with a honeycombinspired structure and automated dynamic solar screen that responds to the sun’s movement. These solar screens respond dynamically and automatically to the angle of the sun, which improves the control over energy consumption, solar radiation, and glare with the ability to allow natural light into the building. This paper is part of the research activities of working group 3 of the European COST Action 1403 on “Adaptive Facades”. Different methods were used for evaluation and these include the following: interviews with the architect, facade engineer, technical control specialist and occupants, reviews of standards and codes, review of energy models, and a systematic design process mapping. A documentation of the case study describing the post-construction occupant comfort and facade operation was prepared. This paper’s audience comprises mainly project managers, architects, and building facade engineers together with facility managers who are concerned with the process of design, construction, and operation of adaptive sunscreens facades. The outcome of this study identifies quantifiable performance indicators and effective strategies for the design and performance evaluation of optimal adaptive facades. [less ▲]

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See detailExperimental and theoretical analysis of shear bolted connections for tubular structures
D'Antimo, Marina ULiege; Demonceau, Jean-François ULiege; Jaspart, Jean-Pierre ULiege et al

in Journal of Constructional Steel Research (2017), 138

In this paper, numerical and experimental investigations devoted to the evaluation of the bearing resistance of tubular members with gusset plates and through-all long bolts are presented. Unlike lap ... [more ▼]

In this paper, numerical and experimental investigations devoted to the evaluation of the bearing resistance of tubular members with gusset plates and through-all long bolts are presented. Unlike lap shear joints, the analysed connection evidences a reduced confinement of the bearing area associated to the use of long bolts and the presence of a gap in the member, which can lead, consequently, to a reduction of the bearing resistance. In order to investigate the behaviour of shear connections made up of thin and thick SHS (Square Hollow Section) profiles and long bolts, an experimental test campaign including 24 specimens and FE simulations have been conducted. Both experimental and FE results have confirmed the influence of local instability on the hole in bearing resistance of thin profiles and the poor accuracy of the available standards for this particular joint typology. In particular, the performed comparisons have shown that, for thin profiles, EC3 model is likely to overestimate the resistance, while for higher thickness of the SHS conservative predictions are obtained. The present paper presents the conducted experimental and numerical investigations, highlighting at the end the need for a proper formulation able to account for the local instability effect on the bearing resistance. [less ▲]

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See detailDetermination of loading scenarios on buildings due to column damage
Colomer, Carles Segura; Hamra, Lotfi; D'Antimo, Marina ULiege et al

in Structures (2017), Volume 12

The majority of imaginable (and relevant) accidental scenarios on building structures are initiated at the ground level by a column suffering damage, mainly due to a localized explosion or a vehicle ... [more ▼]

The majority of imaginable (and relevant) accidental scenarios on building structures are initiated at the ground level by a column suffering damage, mainly due to a localized explosion or a vehicle impact. The transmitted vertical forces from the column to the structure are decisive in understanding the response of the building and are the subject of analysis of this paper. The classic definition of a column loss scenario is extended here by means of a simplified analytical approach to characterize the axial forces appearing in the column during the damage process. A simple closed-form solution is proposed to define the loading scenario on the structure and compared to the classic rectangular (un)loading approach. In certain cases, the proposed analysis shows a more unfavorable loading situation for the structure, which needs to be accounted for during design. [less ▲]

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See detailUltrasonic roll bite measurements in cold rolling - roll stress and deformation
Carretta, Yves; Hunter, Andrew; Boman, Romain ULiege et al

in Journal of Materials Processing Technology (2017), 249

In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip ... [more ▼]

In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip flatness defects and thickness inhomogeneity. To control the process, several online measurements are usually carried out such as the rolling load, forward slip and strip tensions at each stand. Shape defects of the strip are usually evaluated after the last stand of a rolling mill thanks to a flatness measuring roll. However, none of these measurements is made within the roll bite itself due to the harsh conditions taking place in that area. This paper presents a sensor capable of monitoring roll deformations as well as roll radial stresses in situ and in real time. The sensor emits ultrasonic pulses that reflect from the roll surface. The time-of-flight (ToF) of the pulses is recorded during the testing. The sensor system was incorporated into a work roll and tested on a pilot rolling mill. Measurements were taken as steel strips were rolled under different strip elongation. Roll deformation and radial stresses obtained from the experimental data are in good agreement with numerical results computed with a cold rolling model developed in non-linear Finite Element software. [less ▲]

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See detailAn incremental-secant mean-field homogenization method with second statistical moments for elasto-visco-plastic composite materials
Wu, Ling ULiege; Adam, Laurent; Doghri, Issam et al

in Mechanics of Materials (2017), 114

This paper presents an extension of the recently developed incremental-secant mean-field homogenization (MFH) procedure in the context of elasto-plasticity to elasto-visco-plastic composite materials ... [more ▼]

This paper presents an extension of the recently developed incremental-secant mean-field homogenization (MFH) procedure in the context of elasto-plasticity to elasto-visco-plastic composite materials while accounting for second statistical moments. In the incrementalsecant formulation, a virtual elastic unloading is performed at the composite level in order to evaluate the residual stress and strain states in the different phases, from which a secant MFH formulation is applied. When applying the secant MFH process, the Linear-Comparison-Composite is built from the piece-wise heterogeneous residual strain-stress state using naturally isotropic secant tensors defined using either first or second statistical moment values. As a result non-proportional and non-radial loading conditions can be considered because of the incremental-secant formulation, and accurate predictions can be obtained as no isotropization step is required. The limitation of the incremental-secant formulation previously developed was the requirement in case of hard inclusions to cancel the residual stress in the matrix phase, resulting from the composite material unloading, to avoid over-stiff predictions. It is shown in this paper that in the case of hard inclusions by defining a proper second statistical moment estimate of the von Mises stress, the residual stress can be kept in the different composite phases. Moreover it is shown that the method can be extended to visco-plastic behaviors without modifying the homogenization process as the incremental-secant formulation only requires the definition of the secant operator of the different phase material models. Finally, it is shown that although it is also possible to define a proper second statistical moment estimate of the von Mises stress in the case of soft inclusions, this does not improve the accuracy as compared to the increment-secant method with first order statistical moment estimates. [less ▲]

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See detailTree species and time since afforestation drive soil C and N mineralization on former cropland
Rahman, Md Masudur ULiege; Bàrcena, Teresa G; Vesterdal, L

in Geoderma (2017), 305

Conversion from agriculture to forestry is considered a measure for mitigation of atmospheric CO2 but the impacts on soil C and N processes remain still unclear. We investigated heterotrophic respiration ... [more ▼]

Conversion from agriculture to forestry is considered a measure for mitigation of atmospheric CO2 but the impacts on soil C and N processes remain still unclear. We investigated heterotrophic respiration (RH), specific carbon mineralization (CMIN) and nitrogen mineralization (NMIN) in Norway spruce (Picea abies (Karst.) L.) and oak (Quercus robur L.) chronosequences on former cropland by laboratory incubation. The RH was estimated as the release of C per gram soil and CMIN as the release of C per gram of soil organic matter (SOM). Seven Norway spruce stands (16–44 years), eight oak stands (4–43 years), a cropland, a 35 years old permanent pasture and a 200-year-old oak-dominated forest were sampled (0–5 cm and 5–15 cm soil layers) in early spring. The SOM content gradually increased with stand age in 0–5 cm but remained the same in the 5–15 cm soil layer. The RH in the 0–5 cm layer gradually increased with time since afforestation in both tree species while there was no change in CMIN. In 5–15 cm, neither RH nor CMIN changed significantly after afforestation, but oak stands had significantly higher RH than Norway spruce. The NMIN and nitrification in 0–5 cm significantly increased with stand age and only nitrification was higher in oak. In 5–15 cm, only NMIN in oak increased with stand age, but both NMIN and nitrification were significantly higher in oak than spruce. Cropland RH, CMIN and NMIN rates were comparable to those found within the first decades of afforestation, whereas the 200-year-old forest and the pasture generally had RH and NMIN rates similar to the older chronosequence stands. We conclude that potential RH and soil N mineralization increased with time since afforestation and were tree species specific. Soil organic C stock gains observed in this area during the first 45 years after afforestation were not driven by decreased SOM decomposability, leaving increased litter C inputs as a more likely explanation. The lower CMIN in the 200-year-old forest suggests that future studies should include older forests to assess if the stability of C and the retention of N may increase in a longer term perspective. [less ▲]

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See detailÉconomie solidaire et socialisme libertaire Que faire de la forme État ?
Frère, Bruno ULiege

in Mouvements sociaux et économie solidaire (2017)

Nombreux sont ceux qui persistent à renvoyer les prétentions de l’économie solidaire à de douces utopies irréalistes. Mais nous laisserons à leur cynisme les économistes les plus orthodoxes qui restent ... [more ▼]

Nombreux sont ceux qui persistent à renvoyer les prétentions de l’économie solidaire à de douces utopies irréalistes. Mais nous laisserons à leur cynisme les économistes les plus orthodoxes qui restent persuadés qu’il est logique que le monde politique se soumette aux dictats économiques des banques (la Grèce, démolie par les cures d’austérités successives imposées par la BCE en sait quelque chose). Car dans ce chapitre nous aimerions montrer que l’économie solidaire, à titre de programme économique global n’a jamais été une vue de l’esprit. Une telle restitution de l’économie à la société civile a en effet déjà été envisagée et expérimentée par une mouvement politique sérieux, qui connut un certain succès au milieu du19e siècle, époque à laquelle l’organisation capitaliste de la société n’avait pas encore atteint le pouvoir hégémonique qui est le sien aujourd’hui, que ce soit en Europe ou outre-atlantique (Schneiberg, 2007). Il s’agit du socialisme libertaire qui, à l’instar de l’économie solidaire contemporaine, ne visait pas tant la mort de l’État, ou de toute instance de coordination supra-locale, que la fin du capitalisme. Si donc l’ordre capitaliste du monde reste solidement installé, il semble aujourd’hui que des traces de renaissance de cet élan libertaire se font identifiables. Nous tâcherons de discerner dans un premier temps l’économie libertaire qui a émergé au 19e Siècle afin d’apprécier le parallèle possible. Nous montrerons qu’elle repose à l’époque sur quelques grands idées qui restent assez facilement discernables également au principe des structures et réseaux d’économie solidaire contemporaines : autogestion, propriété collective des moyens de production, participation politique, etc. Dans un deuxième temps, nous tâcherons de montrer comment une réflexion sérieuse sur le socialisme libertaire ne peut aujourd’hui se déprendre d’une question déjà cruciale à l’époque : quelle place concéder à l’Etat ou à une quelconque forme d’organisation collective qui s’y rapporte. Nous chercherons alors à indiquer qu’une problématisation sérieuse de cette redéfinition d’une forme fédérative et radicalement démocratisée s’avère urgente dans la pensée libertaire. [less ▲]

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See detailRecommandation pour le dépistage du mésusage d'alcool et de l'intervention brève subséquente par les médecins du travail
Godderis, Lode; Lambrechts, Marie-Claire; Vanmeerbeek, Marc ULiege et al

Report (2017)

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See detailL’événement énonciatif en sémiotique de l’image : de Roland Barthes à la sémiotique tensive
Dondero, Maria Giulia ULiege; Colas-Blaise, Marion

in La part de l'oeil (2017), 31

Dans cet article, nous visons à montrer que la sémiotique tensive développée par Zilberberg permet de revisiter utilement les notions barthésiennes de studium et de punctum et, leur permet de surcroît, de ... [more ▼]

Dans cet article, nous visons à montrer que la sémiotique tensive développée par Zilberberg permet de revisiter utilement les notions barthésiennes de studium et de punctum et, leur permet de surcroît, de devenir un outil pour l’analyse de l’image. [less ▲]

Detailed reference viewed: 39 (1 ULiège)
See detailAnycast on the Move - A First Look at Mobile Anycast Performance
Wassermann, Sarah ULiege; Rula, John P.; Bustamante, Fabian

Poster (2017, November)

Service providers rely on replication to improve service performance and reliability, placing instances in multiple locations and redirecting clients to nearby copies. Anycast is a common mechanism used ... [more ▼]

Service providers rely on replication to improve service performance and reliability, placing instances in multiple locations and redirecting clients to nearby copies. Anycast is a common mechanism used for redirecting clients in a variety of domains from naming to CDNs and video streaming. IP anycast offers a method for making a service IP address available to a routing system from several locations at once, and clients' requests are directed based on BGP routing policies. For operators, IP anycast offers an economic, scalable, and simple approach to replicated services; BGP provides considerable robustness, adapting to changes in service and network availability. For clients, however, the mapping can be suboptimal, unstable, and seemingly chaotic, as routing policies have not only technical motivations, and routing changes can silently shift traffic from one site to another with a consequent loss of shared state and potential performance impact. Given its wide deployment and interesting tradeoffs, IP anycast has been the focus of much recent measurement work. All prior studies have, nevertheless, focused on wired networks despite the growing dominance of mobile Internet. Today, the number of mobile subscriptions is over 7.4~billion, and users spend over 2x times more hours browsing on their smartphones than on any other device, with the corresponding increase on cellular traffic. We present early results on the first study of anycast performance for mobile users. Our evaluation focuses on two distinct anycast services, K-and F-Root, each providing part the DNS Root zone. Both services are widely replicated with publicly available site locations and unicast IP addresses that allow us to evaluate the relative performance of anycast routing to its ``optimal'' (in terms of unicast) site location. We collected active measurements from geographically distributed clients on both cellular and WiFi networks from September 2016 until April 2017, using the Aqualab’s ALICE engine [1]. In each experiment clients launched ping and traceroute measurements towards the root servers’ anycast addresses, as well as to five chosen unicast addresses determined to be the closest to the client in terms of geographic distance, at an hourly rate. Clients also recorded their geographic location, anonymized to a 10 km² area. Our findings show that mobile clients are routed to suboptimal replicas in terms of geographical distance, more frequently while on a cellular connection than on WiFi, with a significant impact on perceived service performance. The phenomenon seems to be more pronounced for K-Root than for F-Root. A possible explanation for the long distances would be that our cellular clients are simply far away from all the available replicas. However, our investigations demonstrate that this is not necessarily the case. Finally, we start to explore the root causes for anycast anomalies in cellular networks. We reveal three classes of anomalies: distant client packet gateways, poor anycast routing within Tier-1 networks, and improper routing out of cellular networks. [1] http://aqualab.cs.northwestern.edu/projects/261-alice [less ▲]

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See detailBIGMOMAL - Big Data Analytics for Mobile Malware Detection
Wassermann, Sarah ULiege; Casas, Pedro

Poster (2017, November)

Mobile malware is on the rise. Due to their popularity, smartphones represent an attractive target for cybercriminals, especially regarding unauthorized access to private user data; smartphones ... [more ▼]

Mobile malware is on the rise. Due to their popularity, smartphones represent an attractive target for cybercriminals, especially regarding unauthorized access to private user data; smartphones incorporate a lot of sensitive information about users, even more than a personal computer. Indeed, besides personal information such as documents, accounts, passwords, contacts, etc., smartphone sensors centralize other sensitive data such as user location, physical activities, etc. In this paper, we study the problem of malware detection in smartphones, using supervised machine learning models and big data analytics frameworks. Using a publicly available dataset for smartphone data analysis (the SherLock data collection, see http://bigdata.ise.bgu.ac.il/sherlock/), we train and benchmark different supervised machine learning models to detect malware apps activity.The Sherlock data collection is a crowdsourcing-based smartphone dataset in which hundreds of features from many different "sensors" or vantage points within the device are monitored, using a tailored smartphone agent. The collection is done during a long-term - 2 years (2015/16), field trial on 50 smartphones used as primary device for 50 different participants. The monitoring agent collects a wide variety of network, software and sensor data at a high sample rate (as low as 5 seconds); in addition, participant devices include a sandbox-like smartphone agent which runs controlled malware apps, perpetrating attacks on the user's device (such as contacts theft, spyware, phishing, etc.), while creating labels for the SherLock dataset. The complete labeled dataset contains more than 10 billion data records, with a total of about 4 TB of data. We additionally complement the labels for malicious apps which might have been installed by participants by analyzing the installed apps' hashes in Virus Total (https://www.virustotal.com), a well-known multi antivirus online scanning system. From the complete dataset, we keep two specific feature categories: all those features related to the network traffic generated by the apps, and all those features corresponding to the footprint of the app on the CPU and internal running processes (e.g., statistics on CPUs, memory usage, linux-level processes information, etc.). The rationale is that some malware activity would be more visible at the network traffic level, whereas some others would be better identified at the local processes level. Using this dataset, we train different machine learning models (e.g., decision trees, neural networks, SVMs, etc.) and verify their accuracy to automatically spot out malicious apps running on the users’ devices. We also apply feature selection strategies to improve results and reduce computational times. Given the size of the dataset, we rely on big data platforms (such as Spark) to perform the analysis, complementing the machine learning based analysis with scikit-learn like pipelines. We evaluate three different concepts, including (i) overall model performance (using multi-fold cross validation on the complete dataset), (ii) generalization of the learned models across different users (train in N-1 users, and test in the remaining user), and (iii) detection accuracy drift along time (train during first month, test the resulting model in the subsequent months). Initial results are very promising, especially regarding overall model performance for decision tree based models. [less ▲]

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See detailMeasuring brain synaptic vesicle protein 2A with positron emission tomography and [18F]UCB-H.
Bahri, Mohamed Ali ULiege; Plenevaux, Alain ULiege; Aerts, Joël ULiege et al

in Alzheimer’s & Dementia: Translational Research & Clinical Interventions (2017), 4(4), 481-486

Introduction: Brain distribution of synaptic vesicle protein 2Awas measured with fluorine-18 UCBH ([18F]UCB-H) and positron emission tomography (PET). Methods: Images of synaptic density were acquired in ... [more ▼]

Introduction: Brain distribution of synaptic vesicle protein 2Awas measured with fluorine-18 UCBH ([18F]UCB-H) and positron emission tomography (PET). Methods: Images of synaptic density were acquired in healthy volunteers (two young participants and two seniors). Input function was measured by arterial blood sampling (arterial input function) and derived from PET images using carotid activity (image-derived input function). Logan graphical analysis was used to estimate regional synaptic vesicle protein 2A distribution volume. Results: [18F]UCB-H uptake was ubiquitous in cortical and subcortical gray matter. Arterial input function and image-derived input function provided regional distribution volume with a high linear relationship. Discussion: The cerebral distribution of [18F]UCB-H is similar to that recently observed with carbon-11 UCB-J ([11C]UCB-J). An accurate [18F]UCB-H quantification can be performed without invasive arterial blood sampling when no suitable reference region is available, using dynamic PET carotid activity. Brain synaptic density can be studied in vivo in normal and pathological aging. [less ▲]

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See detailImproving QoE Prediction in Mobile Video through Machine Learning
Casas, Pedro; Wassermann, Sarah ULiege

in Proc. 8th International Conference on Network of the Future (2017, November)

Despite the massive adoption of HTTP adaptive streaming technology, buffering is still the most harmful event for QoE in video streaming. Previous studies have shown that buffering is not only detrimental ... [more ▼]

Despite the massive adoption of HTTP adaptive streaming technology, buffering is still the most harmful event for QoE in video streaming. Previous studies have shown that buffering is not only detrimental for the overall user experience, but is also highly correlated to viewer engagement. The occurrence of buffering is particularly critical in cellular networks and mobile video deployments, as network conditions are less stable and network resources more limited. In this context, monitoring and properly predicting the QoE of video streaming services becomes paramount to cellular network operators, who need to offer high quality levels to reduce the risks of customers churning for quality dissatisfaction. In this paper, we present a novel approach to multi-dimensional QoE prediction in mobile video using machine learning models. Contrary to previous models for QoE prediction in video streaming, which are generally uni- or low-dimensional and model the impact of single video descriptors independently, we use a high-dimensional input space to model the impact of buffering and initial delay on QoE.We train and test the proposed models on a publicly available mobile video dataset, generated from subjective QoE tests with real viewers. Besides improving prediction performance, the proposed models show that there is a clear influence of other buffering pattern descriptors generally neglected in previous models - in particular those linked to the occurrence of the last stalling event, shedding light on new KPIs to monitor for better QoE assessment in video streaming. [less ▲]

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