•A new analytical methodology for smart grids cyber-physical security is presented.•The method is built on the classical WLS state estimator.•Cyber-attacks are modeled as bad data.•Detection, ...identification and correction of cyber-attacks are investigated.•Test results using synthesized attacks highlight the presented method's accuracy.
This paper presents an analytical methodology for smart grids cyber-physical security based on gross error analysis. The presented methodology is built on the Weighted Least Square (WLS) state estimator (SE) formulation. Although cyber-physical security is a wide subject, in this paper Cyber-Attacks are modeled as bad data. Detection, identification and correction of multiple and simultaneous cyber-attacks on power grid's SCADA system, or network database, are investigated. Cyber-attack detection is made through a Chi-square (χ2) Hypothesis Testing (HT) applied to the composed measurement error (CME). Composed errors are estimated with measurements’ innovation index (II). Cyber-attack identification is made through the Largest Normalized Error Test property. Cyber-attack correction is made considering cyber-attack type and using the composed normalized error (CNE). One important advantage of the presented method is it does not require a previous knowledge of how the attack was performed, as far as it is restricted to a change of measurements, parameters or topology, since the error is estimated and then the bad data is corrected. A significant advantage of this correction is that it avoids potential local or global unobservable conditions, since it does not delete any measurement of the measurement set. Validation of the proposed methodology is made on the IEEE 14-bus and 57-bus systems. Simulations show the reliability and robustness of the proposed methodology even when the cyber-attack occurs simultaneously on SCADA data and network database.
Physical scientists are problem solvers. They are comfortable
"doing" science: they find problems, solve them, and explain their
solutions. Roger Newton believes that his fellow physicists might
be ...too comfortable with their roles as solvers of problems. He
argues that physicists should spend more time thinking about
physics. If they did, he believes, they would become even more
skilled at solving problems and "doing" science. As Newton points
out in this thought-provoking book, problem solving is always
influenced by the theoretical assumptions of the problem solver.
Too often, though, he believes, physicists haven't subjected their
assumptions to thorough scrutiny. Newton's goal is to provide a
framework within which the fundamental theories of modern physics
can be explored, interpreted, and understood. "Surely physics is
more than a collection of experimental results, assembled to
satisfy the curiosity of appreciative experts," Newton writes.
Physics, according to Newton, has moved beyond the describing and
naming of curious phenomena, which is the goal of some other
branches of science. Physicists have spent a great part of the
twentieth century searching for explanations of experimental
findings. Newton agrees that experimental facts are vital to the
study of physics, but only because they lead to the development of
a theory that can explain them. Facts, he argues, should undergird
theory. Newton's explanatory sweep is both broad and deep. He
covers such topics as quantum mechanics, classical mechanics, field
theory, thermodynamics, the role of mathematics in physics, and the
concepts of probability and causality. For Newton the fundamental
entity in quantum theory is the field, from which physicists can
explain the particle-like and wave-like properties that are
observed in experiments. He grounds his explanations in the quantum
field. Although this is not designed as a stand-alone textbook, it
is essential reading for advanced undergraduate students, graduate
students, professors, and researchers. This is a clear, concise,
up-to-date book about the concepts and theories that underlie the
study of contemporary physics. Readers will find that they will
become better-informed physicists and, therefore, better thinkers
and problem solvers too.
Abstract
The
Drosophila
chordotonal neuron cilium is the site of mechanosensory transduction. The cilium has a 9 + 0 axoneme structure and is highly sub-compartmentalised, with proximal and distal ...zones harbouring different TRP channels and the proximal zone axoneme also being decorated with axonemal dynein motor complexes. The activity of the dynein complexes is essential for mechanotransduction. We investigate the localisation of TRP channels and dynein motor complexes during ciliogenesis. Differences in timing of TRP channel localisation correlate with order of construction of the two ciliary zones. Dynein motor complexes are initially not confined to their target proximal zone, but ectopic complexes beyond the proximal zone are later cleared, perhaps by retrograde transport. Differences in transient distal localisation of outer and inner dynein arm complexes (ODAs and IDAs) are consistent with previous suggestions from unicellular eukaryotes of differences in processivity during intraflagellar transport. Stable localisation depends on the targeting of their docking proteins in the proximal zone. For ODA, we characterise an ODA docking complex (ODA-DC) that is targeted directly to the proximal zone. Interestingly, the subunit composition of the ODA-DC in chordotonal neuron cilia appears to be different from the predicted ODA-DC in
Drosophila
sperm.
In order to assess the ability of purely crust-driven glitch models to match the observed glitch activity in the Vela pulsar, we conduct a systematic analysis of the dependence of the fractional ...moment of inertia of the inner crustal neutrons on the stiffness of the nuclear symmetry energy at saturation density L. We take into account both crustal entrainment and the fact that only a fraction Y
g of the core neutrons may couple to the crust on the glitch-rise time-scale. We use a set of consistently generated crust and core compositions and equations of state (EoSs) which are fit to results of low-density pure neutron matter calculations. When entrainment is included at the level suggested by recent microscopic calculations and the core is fully coupled to the crust, the model is only able to account for the Vela glitch activity for a 1.4 M⊙ star if the EoS is particularly stiff L > 100 MeV. However, an uncertainty of about 10 per cent in the crust–core transition density and pressure allows for the Vela glitch activity to be marginally accounted for in the range L ≈ 30–60 MeV consistent with a range of experimental results. Alternatively, only a small amount of core neutrons need be involved. If less than 50 per cent of the core neutrons are coupled to the crust during the glitch, we can also account for the Vela glitch activity using crustal neutrons alone for EoSs consistent with the inferred range of L. We also explore the possibility of Vela being a high-mass neutron star, and of crustal entrainment being reduced or enhanced relative to its currently predicted values.
Recent articles discussing cases of brain cancer in interventionalists have raised concerns regarding the hazards of occupational exposure to ionizing radiation. We review the basics of radiation ...dose and the potential radiation effects, particularly as they pertain to the operator. Then we present the data regarding the risk of each type of radiation effect to the fluoroscopy operator and staff, with special attention on cancer induction, radiation-induced cataracts, and the pregnant operator.
Although the evidence overwhelmingly shows that exposure to higher doses of radiation carries a risk of cancer and tissue reactions, the risks of chronic exposure to low-level radiation are less clear. Many studies examining occupational exposure to radiation fail to show an increased risk of stochastic effects of radiation, but the positive results raise concern that the studies are underpowered to consistently detect the small risk. The lack of information in these studies about radiation doses and adherence to radiation protection further confound their interpretation. Large prospective studies of populations with occupational exposure to low-level radiation might clarify this issue. More clearly established are the risks of radiation to the fetus and the risk of cataracts in interventional cardiologists and interventional radiologists. Interventionalists can mitigate these risks by following established radiation safety practices.
Assembly of synapses requires proper coordination between pre- and postsynaptic elements. Identification of cellular and molecular events in synapse formation and maintenance is a key step to ...understand human perception, learning, memory, and cognition. A key role for astrocytes in synapse formation and function has been proposed. Here, we show that transforming growth factor β (TGF-β) signaling is a novel synaptogenic pathway for cortical neurons induced by murine and human astrocytes. By combining gain and loss of function approaches, we show that TGF-β1 induces the formation of functional synapses in mice. Further, TGF-β1-induced synaptogenesis involves neuronal activity and secretion of the co-agonist of the NMDA receptor, d-serine. Manipulation of d-serine signaling, by either genetic or pharmacological inhibition, prevented the TGF-β1 synaptogenic effect. Our data show a novel molecular mechanism that might impact synaptic function and emphasize the evolutionary aspect of the synaptogenic property of astrocytes, thus shedding light on new potential therapeutic targets for synaptic deficit diseases.
Background: Synapse formation and function is modulated by intrinsic and extrinsic non-autonomous factors.
Results: Astrocytes induce synapse formation through TGF-β1 pathway. TGF-β1 synaptogenic property is dependent on d-serine signaling.
Conclusion: TGF-β induces excitatory glutamatergic synapses in vertebrates.
Significance: This is a novel molecular mechanism that might impact synaptic function and shed light on new potential therapeutic targets for synaptic deficit diseases.
Mutualistic associations between bacteria and eukaryotes occur ubiquitously in nature, forming the basis for key ecological and evolutionary innovations. Some of the most prominent examples of these ...symbioses are chemosynthetic bacteria and marine invertebrates living in the absence of sunlight at deep-sea hydrothermal vents and in sediments rich in reduced sulfur compounds. Here, chemosynthetic bacteria living in close association with their hosts convert CO
2
or CH
4
into organic compounds and provide the host with necessary nutrients. The dominant macrofauna of hydrothermal vent and cold seep ecosystems all depend on the metabolic activity of chemosynthetic bacteria, which accounts for almost all primary production in these complex ecosystems. Many of these enigmatic mutualistic associations are found within the molluscan class Bivalvia. Currently, chemosynthetic symbioses have been reported from five distinct bivalve families (Lucinidae, Mytilidae, Solemyidae, Thyasiridae, and Vesicomyidae). This brief review aims to provide an overview of the diverse physiological and genetic adaptations of symbiotic chemosynthetic bacteria and their bivalve hosts.
Prior infection can generate protective immunity against subsequent infection, although the efficacy of such immunity can vary considerably. Live-attenuated vaccines (LAVs) are one of the most ...effective methods for mimicking this natural process, and analysis of their efficacy has proven instrumental in the identification of protective immune mechanisms. Here, we address the question of what makes a LAV efficacious by characterising immune responses to a LAV, termed TAS2010, which is highly protective (80–90%) against lethal murine salmonellosis, in comparison with a moderately protective (40–50%) LAV, BRD509. Mice vaccinated with TAS2010 developed immunity systemically and were protected against gut-associated virulent infection in a CD4
+
T cell-dependent manner. TAS2010-vaccinated mice showed increased activation of Th1 responses compared with their BRD509-vaccinated counterparts, leading to increased Th1 memory populations in both lymphoid and non-lymphoid organs. The optimal development of Th1-driven immunity was closely correlated with the activation of CD11b
+
Ly6G
neg
Ly6C
hi
inflammatory monocytes (IMs), the activation of which can be modulated proportionally by bacterial load
in vivo
. Upon vaccination with the LAV, IMs expressed T cell chemoattractant CXCL9 that attracted CD4
+
T cells to the foci of infection, where IMs also served as a potent source of antigen presentation and Th1-promoting cytokine IL-12. The expression of MHC-II in IMs was rapidly upregulated following vaccination and then maintained at an elevated level in immune mice, suggesting IMs may have a role in sustained antigen stimulation. Our findings present a longitudinal analysis of CD4
+
T cell development post-vaccination with an intracellular bacterial LAV, and highlight the benefit of inflammation in the development of Th1 immunity. Future studies focusing on the induction of IMs may reveal key strategies for improving vaccine-induced T cell immunity.
Microbial ecologists now routinely utilize next-generation sequencing methods to assess microbial diversity in the environment. One tool heavily utilized by many groups is the Naïve Bayesian ...Classifier developed by the Ribosomal Database Project (RDP-NBC). However, the consistency and confidence of classifications provided by the RDP-NBC is dependent on the training set utilized.
We explored the stability of classification of honey bee gut microbiota sequences by the RDP-NBC utilizing three publically available ribosomal RNA sequence databases as training sets: ARB-SILVA, Greengenes and RDP. We found that the inclusion of previously published, high-quality, full-length sequences from 16S rRNA clone libraries improved the precision in classification of novel bee-associated sequences. Specifically, by including bee-specific 16S rRNA gene sequences a larger fraction of sequences were classified at a higher confidence by the RDP-NBC (based on bootstrap scores).
Results from the analysis of these bee-associated sequences have ramifications for other environments represented by few sequences in the public databases or few bacterial isolates. We conclude that for the exploration of relatively novel habitats, the inclusion of high-quality, full-length 16S rRNA gene sequences allows for a more confident taxonomic classification.
While Salmonella enterica is seen as an archetypal facultative intracellular bacterial pathogen where protection is mediated by CD4+ T cells, identifying circulating protective cells has proved very ...difficult, inhibiting steps to identify key antigen specificities. Exploiting a mouse model of vaccination, we show that the spleens of C57BL/6 mice vaccinated with live-attenuated Salmonella serovar Typhimurium (S. Typhimurium) strains carried a pool of IFN-γ+ CD4+ T cells that could adoptively transfer protection, but only transiently. Circulating Salmonella-reactive CD4+ T cells expressed the liver-homing chemokine receptor CXCR6, accumulated over time in the liver and assumed phenotypic characteristics associated with tissue-associated T cells. Liver memory CD4+ T cells showed TCR selection bias and their accumulation in the liver could be inhibited by blocking CXCL16. These data showed that the circulation of CD4+ T cells mediating immunity to Salmonella is limited to a brief window after which Salmonella-specific CD4+ T cells migrate to peripheral tissues. Our observations highlight the importance of triggering tissue-specific immunity against systemic infections.
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