45 research outputs found

    Time-series clustering for sensor fault detection in large-scale Cyber-Physical Systems

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    Large-scale Cyber-Physical Systems (CPSs) are information systems that involve a vast network of sensor nodes and other devices that stream observations in real-time and typically are deployed in uncontrolled, broad geographical terrains. Sensor node failures are inevitable and unpredictable events in large-scale CPSs, which compromise the integrity of the sensors measurements and potentially reduce the quality of CPSs services and raise serious concerns related to CPSs safety, reliability, performance, and security. While many studies were conducted to tackle the challenge of sensor nodes failure detection using domain-specific solutions, this paper proposes a novel sensor nodes failure detection approach and empirically evaluates its validity using a real-world case study. This paper investigates time-series clustering techniques as a feasible solution to identify sensor nodes malfunctions by detecting long-segmental outliers in their observations' time series. Three different time-series clustering techniques have been investigated using real-world observations collected from two various sensor node networks, one of which consists of 275 temperature sensors distributed around London. This study demonstrates that time-series clustering effectively detects sensor node's continuous (halting/repeating) and incipient faults. It also showed that the feature-based time series clustering technique is a more efficient long-segmental outliers detection mechanism compared to shape-based time-series clustering techniques such as DTW and K-Shape, mainly when applied to shorter time-series windows

    Content Discovery Advertisements: An Explorative Analysis

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    Content discovery advertisements are type of native ads which have gained traction for driving ad traffic. These advertisements are being hosted on supposedly reputed websites and their popularity has been growing however it has been reported in the media that these ads are deploying click bait ads. In this research, these ads were evaluated for a period of one month to study and examine their credibility. It was found that significant percentage of these ads were malicious in nature

    A colour-excess extinction map of the southern Galactic disc from the VVV and GLIMPSE surveys

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    An improved high-resolution and deep A Ks foreground dust extinction map is presented for the Galactic disc area within 295◦ ≾ l ≾ 350◦, −1.0◦ ≾ b ≾ +1.0◦. At some longitudes the map reaches up to |b| ~ 2.25◦, for a total of ~148 deg 2. The map was constructed via the Rayleigh–Jeans colour excess (RJCE) technique based on deep near-infrared (NIR) and mid-infrared (MIR) photometry. The new extinction map features a maximum bin size of 1 arcmin, and relies on NIR observations from the Two Micron All-Sky Survey (2MASS) and new data from ESO’s Vista Variables in the Vía Láctea (VVV) survey, in concert with MIR observations from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire. The VVV photometry penetrates ~4 mag fainter than 2MASS, and provides enhanced sampling of the underlying stellar populations in this heavily obscured region. Consequently, the new results supersede existing RJCE maps tied solely to brighter photometry, revealing a systematic underestimation of extinction in prior work that was based on shallower data. The new high-resolution and large-scale extinction map presented here is readily available to the community through a web query interface.Peer reviewe

    The VVV near-IR galaxy catalogue in a Northern part of the Galactic disc

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    The automated identification of extragalactic objects in large surveys provides reliable and reproducible samples of galaxies in less time than procedures involving human interaction. However, regions near the Galactic disc are more challenging due to the dust extinction. We present the methodology for the automatic classification of galaxies and non-galaxies at low Galactic latitude regions using both images and, photometric and morphological near-IR data from the VVVX survey. Using the VVV-NIRGC, we analyse by statistical methods the most relevant features for galaxy identification. This catalogue was used to train a CNN with image data and an XGBoost model with both photometric and morphological data and then to generate a dataset of extragalactic candidates. This allows us to derive probability catalogues used to analyse the completeness and purity as a function of the configuration parameters and to explore the best combinations of the models. As a test case, we apply this methodology to the Northern disc region of the VVVX survey, obtaining 172,396 extragalatic candidates with probabilities of being galaxies. We analyse the performance of our methodology in the VVV disc, reaching an F1-score of 0.67, a 65 per cent purity and a 69 per cent completeness. We present the VVV-NIR Galaxy Catalogue: Northern part of the Galactic disc comprising 1,003 new galaxies, with probabilities greater than 0.6 for either model, with visual inspection and with only 2 previously identified galaxies. In the future, we intend to apply this methodology to other areas of the VVVX survey.Comment: 12 pages, 14 figures, accepted in MNRA

    Differential, Phosphorylation Dependent Trafficking of AQP2 in LLC-PK1 Cells

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    The kidney maintains water homeostasis by modulating aquaporin 2 (AQP2) on the plasma membrane of collecting duct principal cells in response to vasopressin (VP). VP mediated phosphorylation of AQP2 at serine 256 is critical for this effect. However, the role of phosphorylation of other serine residues in the AQP2 C-terminus is less well understood. Here, we examined the effect of phosphorylation of S256, S261 and S269 on AQP2 trafficking and association with recycling pathway markers. We used LLC-PK1 cells expressing AQP2(S-D) or (S-A) phospho mutants and a 20°C cold block, which allows endocytosis to continue, but prevents protein exit from the trans Golgi network (TGN), inducing formation of a perinuclear AQP2 patch. AQP2-S256D persists on the plasma membrane during cold block, while wild type AQP2, AQP2-S256A, S261A, S269A and S269D are internalized and accumulate in the patch. Development of this patch, a measure of AQP2 internalization, was most rapid with AQP2-S256A, and slowest with S261A and S269D. AQP2-S269D exhibited a biphasic internalization profile with a significant amount not internalized until 150 minutes of cold block. After rewarming to 37°C, wt AQP2, AQP2-S261A and AQP2-S269D rapidly redistributed throughout the cytoplasm within 20 minutes, whereas AQP2-S256A dissipated more slowly. Colocalization of AQP2 mutants with several key vesicular markers including clathrin, HSP70/HSC70, EEA, GM130 and Rab11 revealed no major differences. Overall, our data provide evidence supporting the role of S256 and S269 in the maintenance of AQP2 at the cell surface and reveal the dynamics of internalization and recycling of differentially phosphorylated AQP2 in cell culture

    Insights into Minor Group Rhinovirus Uncoating: The X-ray Structure of the HRV2 Empty Capsid

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    Upon attachment to their respective receptor, human rhinoviruses (HRVs) are internalized into the host cell via different pathways but undergo similar structural changes. This ultimately results in the delivery of the viral RNA into the cytoplasm for replication. To improve our understanding of the conformational modifications associated with the release of the viral genome, we have determined the X-ray structure at 3.0 Å resolution of the end-stage of HRV2 uncoating, the empty capsid. The structure shows important conformational changes in the capsid protomer. In particular, a hinge movement around the hydrophobic pocket of VP1 allows a coordinated shift of VP2 and VP3. This overall displacement forces a reorganization of the inter-protomer interfaces, resulting in a particle expansion and in the opening of new channels in the capsid core. These new breaches in the capsid, opening one at the base of the canyon and the second at the particle two-fold axes, might act as gates for the externalization of the VP1 N-terminus and the extrusion of the viral RNA, respectively. The structural comparison between native and empty HRV2 particles unveils a number of pH-sensitive amino acid residues, conserved in rhinoviruses, which participate in the structural rearrangements involved in the uncoating process

    Extracellular and Luminal pH Regulation by Vacuolar H⁺-ATPase Isoform Expression and Targeting to the Plasma Membrane and Endosomes

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    Plasma membrane vacuolar H+ -ATPase (pm-V-ATPase) activity of tumor cells is a major factor in control of cytoplasmic and extracellular pH and metastatic potential, but the isoforms involved and the factors governing plasma membrane recruitment remain uncertain. Here, we examined expression, distribution and activity of V- ATPase isoforms in invasive prostate adenocarcinoma (PC-3) cells. Isoforms 1 and 3 were the most highly expressed forms of membrane subunit a, with a1 and a3 the dominant plasma membrane isoforms. Correlation between pm-V-ATPase activity and invasiveness was limited, but RNAi knockdown of either a isoform did slow cell proliferation and inhibit invasion in vitro. Isoform a1 was recruited to the cell surface from the early endosome/recycling complex pathway, its knockdown arresting transferrin receptor (TfR) recycling. Isoform a3 was associated with the late endosomal/lysosomal compartment. Both a isoforms associated with accessory protein Ac45, knockdown of which stalled transit of a1 and Tf-TfR, decreased proton efflux and reduced cell growth and invasiveness, this latter effect at least partly due to decreased delivery of the membrane-bound matrix metalloproteinase MMP-14 to the plasma membrane. These data indicate that in prostatic carcinoma cells, a1 and a3 isoform populations predominate in different compartments where they maintain different luminal pH. Ac45 plays a central role in navigating the V-ATPase to the plasma membrane, and hence is an important factor in expression of the invasive phenotype

    Data quality challenges in large-scale cyber-physical systems: A systematic review

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    Cyber-physical systems (CPSs) are integrated systems engineered to combine computational control algorithms and physical components such as sensors and actuators, effectively using an embedded communication core. Smart cities can be viewed as large-scale, heterogeneous CPSs that utilise technologies like the Internet of Things (IoT), surveillance, social media, and others to make informed decisions and drive the innovations of automation in urban areas. Such systems incorporate multiple layers and complex structure of hardware, software, analytical algorithms, business knowledge and communication networks, and operate under noisy and dynamic conditions. Thus, large-scale CPSs are vulnerable to enormous technical and operational challenges that may compromise the quality of data of their applications and accordingly reduce the quality of their services. This paper presents a systematic literature review to investigate data quality challenges in smart-cities large-scale CPSs and to identify the most common techniques used to address these challenges. This systematic literature review showed that significant work had been conducted to address data quality management challenges in smart cities, large-scale CPS applications. However, still, more is required to provide a practical, comprehensive data quality management solution to detect errors in sensor nodes’ measurements associated with the main data quality dimensions of accuracy, timeliness, completeness, and consistency. No systematic or generic approach was demonstrated for detecting sensor nodes and sensor node networks failures in large-scale CPS applications. Moreover, further research is required to address the challenges of ensuring the quality of the spatial and temporal contextual attributes of sensor nodes’ observations