1,853 research outputs found
Mobile radio interferometric geodetic systems
Operation of the Astronomical Radio Interferometric Earth Surveying (ARIES) in a proof of concept mode is discussed. Accuracy demonstrations over a short baseline, a 180 km baseline, and a 380 km baseline are documented. Use of ARIES in the Sea Slope Experiment of the National Geodetic Survey to study the apparent differences between oceanographic and geodetic leveling determinations of the sea surface along the Pacific Coast is described. Intergration of the NAVSTAR Global Positioning System and a concept called SERIES (Satellite Emission Radio Interferometric Earth Surveying) is briefly reviewed
Statistical analysis driven optimized deep learning system for intrusion detection
Attackers have developed ever more sophisticated and intelligent ways to hack
information and communication technology systems. The extent of damage an
individual hacker can carry out upon infiltrating a system is well understood.
A potentially catastrophic scenario can be envisaged where a nation-state
intercepting encrypted financial data gets hacked. Thus, intelligent
cybersecurity systems have become inevitably important for improved protection
against malicious threats. However, as malware attacks continue to dramatically
increase in volume and complexity, it has become ever more challenging for
traditional analytic tools to detect and mitigate threat. Furthermore, a huge
amount of data produced by large networks has made the recognition task even
more complicated and challenging. In this work, we propose an innovative
statistical analysis driven optimized deep learning system for intrusion
detection. The proposed intrusion detection system (IDS) extracts optimized and
more correlated features using big data visualization and statistical analysis
methods (human-in-the-loop), followed by a deep autoencoder for potential
threat detection. Specifically, a pre-processing module eliminates the outliers
and converts categorical variables into one-hot-encoded vectors. The feature
extraction module discard features with null values and selects the most
significant features as input to the deep autoencoder model (trained in a
greedy-wise manner). The NSL-KDD dataset from the Canadian Institute for
Cybersecurity is used as a benchmark to evaluate the feasibility and
effectiveness of the proposed architecture. Simulation results demonstrate the
potential of our proposed system and its outperformance as compared to existing
state-of-the-art methods and recently published novel approaches. Ongoing work
includes further optimization and real-time evaluation of our proposed IDS.Comment: To appear in the 9th International Conference on Brain Inspired
Cognitive Systems (BICS 2018
Single-cell landscape in mammary epithelium reveals bipotent-like cells associated with breast cancer risk and outcome
Adult stem-cells may serve as the cell-of-origin for cancer, yet their unbiased identification in
single cell RNA sequencing data is challenging due to the high dropout rate. In the case of
breast, the existence of a bipotent stem-like state is also controversial. Here we apply a
marker-free algorithm to scRNA-Seq data from the human mammary epithelium, revealing a
high-potency cell-state enriched for an independent mammary stem-cell expression module.
We validate this stem-like state in independent scRNA-Seq data. Our algorithm further
predicts that the stem-like state is bipotent, a prediction we are able to validate using FACS
sorted bulk expression data. The bipotent stem-like state correlates with clinical outcome in
basal breast cancer and is characterized by overexpression of YBX1 and ENO1, two modulators of basal breast cancer risk. This study illustrates the power of a marker-free computational framework to identify a novel bipotent stem-like state in the mammary epithelium
Nuclear regions as seen with LOFAR international baselines: A high-resolution study of the recurrent activity
Context. Radio galaxies dominate the sky at radio wavelengths and represent an essential piece in the galaxy evolution puzzle. High-resolution studies focussed on statistical samples of radio galaxies are expected to shed light on the triggering mechanisms of the active galactic nucleus in their centre, alternating between the phases of activity and quiescence.Aims. For this work, we zoomed in on the sub-arcsec radio structures in the central regions of the 35 radio galaxies in the area covering 6.6 deg2 of the Lockman Hole region. The sources studied here were previously classified as active, remnant, and candidate restarted radio galaxies based on the LOw Frequency ARray (LOFAR) observations at 150 MHz. We examined the morphologies and studied the spectral properties of their central regions to explore their evolutionary stages and to revise the morphological and spectral criteria used to select the initial sample.Methods. We used the newly available LOFAR 150 MHz image obtained using international baselines, yielding a resolution of 0.38″ × 0.30″, making this the first systematic study of the nuclear regions at such a high resolution and low frequency. We used publicly available images from the Faint Images of the Radio Sky at Twenty-cm survey at 1.4 GHz and the Karl G. Jansky Very Large Array (VLA) Sky Survey at 3 GHz to achieve our goals. In addition, for one of the restarted candidates, we present new dedicated observations with the VLA at 3 GHz.Results. We characterised the central regions of the radio galaxies in our sample and found various morphologies, some even mimicking well-known double-double radio galaxies but on a smaller scale, that is, a few tens of kiloparsecs for the size of the restarted activity. We also see the beginnings of active jets or distinct detections unrelated to the large-scale structure. Furthermore, we found a variety of radio spectra characterising the sources in our sample, such as flat, steep, or peaked in the frequency range between 150 MHz and 3 GHz, indicative of the different life-cycle phases of the sources in our sample. Based on these analyses, we confirm five out of six previously considered restarted candidates and identify three more restarted candidates from the active sample. As the number of restarted candidates still exceeds that of remnant candidates, this is consistent with previous results suggesting that the restarted phase can occur after a relatively short remnant phase (i.e. a few tens of millions of years)
Evidence for aquaporin-mediated water transport in nematocytes of the jellyfish Pelagia noctiluca.
Nematocytes, the stinging cells of Cnidarians, have a cytoplasm confined to a thin rim. The main cell body is occupied by an organoid, the nematocyst, containing the stinging tubule and venom. Exposed to hypotonic shock, nematocytes initially swell during an osmotic phase (OP) and then undergo regulatory volume decrease (RVD) driven by K+, Cl- and obligatory water extrusion mechanisms. The purpose of this report is to characterize the OP. Nematocytes were isolated by the NaSCN/Ca2+ method from tentacles of the jellyfish Pelagia noctiluca, collected in the Strait of Messina, Italy. Isolated nematocytes were subjected to hyposmotic shock in 65% artificial seawater (ASW) for 15 min. The selective aquaporin water channel inhibitor HgCl2 (0.1-25 µM) applied prior to osmotic shock prevented the OP and thus RVD. These effects were attenuated in the presence of 1mM dithiothreitol (DTT), a mercaptide bond reducing agent. AgNO3 (1 µM) and TEA (tetraethylammonium, 100 µM), also reported to inhibit water transport, did not alter the OP but significantly diminished RVD, suggesting different modes of action for the inhibitors tested. Based on estimates of the nematocyte surface area and volume, and OP duration, a relative water permeability of ∼10-7 cm/sec was calculated and the number of putative aquaporin molecules mediating the OP was estimated. This water permeability is 3-4 orders of magnitude lower in comparison to higher order animals and may constitute an evolutionary advantage for Cnidarian survival
Mechanisms of hyposmotic volume regulation in isolated nematocytes of the anthozoan Aiptasia diaphana.
The nature and role of potassium (K) and water transport mediating hyposmotically-induced regulatory volume decrease (RVD) were studied in nematocytes dissociated with 605 mM thiocyanate from aconti
Epidemiology and Surgical Management of Foreign Bodies in the Liver in the Pediatric Population: A Systematic Review of the Literature
Retention of foreign bodies (FB) in the liver parenchyma is a rare event in children but it can bring a heavy burden in terms of immediate and long-term complications. Multiple materials can migrate inside the liver. Clinical manifestations may vary, depending on the nature of the foreign body, its route of penetration and timing after the initial event. Moreover, the location of the FB inside the liver parenchyma may pose specific issues related to the possible complications of a challenging surgical extraction. Different clinical settings and the need for highly specialized surgical skills may influence the overall management of these children. Given the rarity of this event, a systematic review of the literature on this topic was conducted and confirmed the pivotal role of surgery in the pediatric population
Epidemiology and Surgical Management of Foreign Bodies in the Liver in the Pediatric Population: A Systematic Review of the Literature
Retention of foreign bodies (FB) in the liver parenchyma is a rare event in children but it can bring a heavy burden in terms of immediate and long-term complications. Multiple materials can migrate inside the liver. Clinical manifestations may vary, depending on the nature of the foreign body, its route of penetration and timing after the initial event. Moreover, the location of the FB inside the liver parenchyma may pose specific issues related to the possible complications of a challenging surgical extraction. Different clinical settings and the need for highly specialized surgical skills may influence the overall management of these children. Given the rarity of this event, a systematic review of the literature on this topic was conducted and confirmed the pivotal role of surgery in the pediatric population
A low frequency sub-arcsecond view of powerful radio galaxies in rich-cluster environments: 3C 34 and 3C 320
Models of radio galaxy physics have been primarily based on high frequency
(1 GHz) observations of their jets, hotspots, and lobes. Without
highly resolved low frequency observations, which provide information on older
plasma, our understanding of the dynamics of radio galaxies and their
interaction with their environment is limited. Here, we present the first
sub-arcsecond (0.3") resolution images at 144 MHz of two powerful radio
galaxies situated in rich cluster environments, namely 3C 34 and 3C 320, using
the International Low Frequency Array Telescope. We detect for the first time
at low frequencies a plethora of structures in these objects, including
strikingly large filaments across the base of the lobes in both sources, which
are spatially associated with dense regions in the ambient medium. For 3C 34 we
report a spectral flattening in the region of the central filament, suggesting
that the origin of the filaments is related to the presence of large-scale
ordered magnetic fields. We also report periodic total intensity and spectral
index banding of diffuse emission in the eastern lobe, seen for the first time
in radio galaxy lobes. The hotspot complexes are resolved into multiple
fragments of varying structure and spectral index; we discuss the implications
for particle acceleration and jet termination models. We find at most smooth
gradients in the spectral behaviour of the hotspot structure suggesting that
particle acceleration, if present, may be occurring throughout the complex, in
contrast to simple models, but different jet termination models may apply to
both sources.Comment: 16 pages, 7 figures, 2 tables. Accepted for publication in Monthly
Notices of the Royal Astronomical Society, 2023 February 0
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