33,022 research outputs found
Exploiting Temporal Complex Network Metrics in Mobile Malware Containment
Malicious mobile phone worms spread between devices via short-range Bluetooth
contacts, similar to the propagation of human and other biological viruses.
Recent work has employed models from epidemiology and complex networks to
analyse the spread of malware and the effect of patching specific nodes. These
approaches have adopted a static view of the mobile networks, i.e., by
aggregating all the edges that appear over time, which leads to an approximate
representation of the real interactions: instead, these networks are inherently
dynamic and the edge appearance and disappearance is highly influenced by the
ordering of the human contacts, something which is not captured at all by
existing complex network measures. In this paper we first study how the
blocking of malware propagation through immunisation of key nodes (even if
carefully chosen through static or temporal betweenness centrality metrics) is
ineffective: this is due to the richness of alternative paths in these
networks. Then we introduce a time-aware containment strategy that spreads a
patch message starting from nodes with high temporal closeness centrality and
show its effectiveness using three real-world datasets. Temporal closeness
allows the identification of nodes able to reach most nodes quickly: we show
that this scheme can reduce the cellular network resource consumption and
associated costs, achieving, at the same time, a complete containment of the
malware in a limited amount of time.Comment: 9 Pages, 13 Figures, In Proceedings of IEEE 12th International
Symposium on a World of Wireless, Mobile and Multimedia Networks (WOWMOM '11
Pneumothorax and Pneumomediastinum in a Sputum Positive Tuberculosis Patient: The Continuous Diaphragm Sign
Secondary pneumothorax is a very common medical emergency. At times it is associated with pneumomediastinum, which could be fatal at times if not identified. We present a case of a 11 years old sputum positive child who presented with both these conditions and was diagnosed on chest x ray
Glutathione S-Transferase activity and total thiol status in chronic alcohol abusers before and 30 days after alcohol abstinence
Background: Glutathione S Transferase (GST) has been involved in detoxification process in the liver and its activity has been shown to be increased in alcohol abusers. In the current work we measured the GST activity, total thiol status, AST, ALT, and direct bilirubin in chronic alcohol abusers before and 30 days after alcohol abstinence and lifestyle modification. Methods: Serum and urine GST activity and total thiol status were determined using spectrophotometric methods and serum transaminases were determined using clinical chemistry analyzer. Results: We found,significant increase in serum and urine GST (p<0.001), AST (p<0.001), ALT (p<0.001), and decrease in total thiol status (p<0.001) in chronic alcohol abusers. GST activity significantly decreased (p<0.001) and total thiol status were improved significantly (p<0.001) 30 days after alcohol abstinence and lifestyle modification. Conclusion: This study provides preliminary data to suggest the role of GST as prognostic indicator of alcohol abstinence with possible trend towards an improvement in liver function
Explicit approximate controllability of the Schr\"odinger equation with a polarizability term
We consider a controlled Schr\"odinger equation with a dipolar and a
polarizability term, used when the dipolar approximation is not valid. The
control is the amplitude of the external electric field, it acts non linearly
on the state. We extend in this infinite dimensional framework previous
techniques used by Coron, Grigoriu, Lefter and Turinici for stabilization in
finite dimension. We consider a highly oscillating control and prove the
semi-global weak stabilization of the averaged system using a Lyapunov
function introduced by Nersesyan. Then it is proved that the solutions of the
Schr\"odinger equation and of the averaged equation stay close on every finite
time horizon provided that the control is oscillating enough. Combining these
two results, we get approximate controllability to the ground state for the
polarizability system
Is fundamental frequency a cue to aspiration in initial stops?
One production and one perception experiment were conducted to investigate the interaction of consonant voicing and fundamental frequency at the onset of voicing (onset f0) in Cantonese, a tonal language. Consonantal voicing in English can affect onset f0 up to 100 ms after voicing onset, but existing research provides inconclusive information regarding the effects of voicing on f0 in tonal languages where f0 variability is constrained by the demands of the lexical tone system. Previous research on consonantal effects on onset f0 provides two contrasting theories: These effects may be automatic, resulting from physiological constraints inherent to the speech production mechanism or they may be controlled, produced as part of a process of cue enhancement for the perception of laryngeal contrasts. Results of experiment 1 showed that consonant aspiration affects onset f0 in Cantonese only within the first 10 ms following voicing onset, comparable to results for other tonal languages. Experiment 2 showed that Cantonese listeners can use differences in onset f0 to cue perception of the voicing contrast, but the minimum extent of f0 perturbation necessary for this is greater than is found in Cantonese production, and comparable to that observed in acoustic studies of nontonal languages. These results suggest that consonantal effects on onset f0 are at least partially controlled by talkers, but that their role in the perception of voicing/aspiration may be a consequence of language independent properties of audition rather than listeners' experience with the phonological contrasts of a specific language.published_or_final_versio
Probing the strength of infants' preference for helpers over hinderers:Â two replication attempts of Hamlin and Wynn (2011)
Several studies indicate that infants prefer individuals who act prosocially over those
who act antisocially toward unrelated third parties. In the present study, we focused on a
paradigm published by Kiley Hamlin and Karen Wynn in 2011. In this study, infants were
habituated to a live puppet show in which a protagonist tried to open a box to retrieve a toy
placed inside. The protagonist was either helped by a second puppet (the âHelperâ), or hindered by a third puppet (the âHindererâ). At test, infants were presented with the Helper and the Hinderer, and encouraged to reach for one of them. In the original study, 75% of 9-month-olds selected the Helper, arguably demonstrating a preference for prosocial over antisocial individuals. We conducted two studies with the aim of replicating this result. Each
attempt was performed by a different group of experimenters. Study 1 followed the methods
of the published study as faithfully as possible. Study 2 introduced slight modifications to the
stimuli and the procedure following the guidelines generously provided by Kiley Hamlin and
her collaborators. Yet, in our replication attempts, 9-month-oldsâ preference for helpers over hinderers did not differ significantly from chance (62.5% and 50%, respectively, in Studies 1 and 2). Two types of factors could explain why our results differed from those of Hamlin and Wynn: minor methodological dissimilarities (in procedure, materials, or the population
tested), or the effect size being smaller than originally assumed. We conclude that fine
methodological details that are crucial to infantsâ
success in this task need to be identified to
ensure the replicability of the original result
Dependence of carrier mobility on grain mosaic spread in ă001ă-oriented Si films grown on polycrystalline substrates
We studied the dependence of carrier mobility on grain mosaic spread for ă001ă-oriented, 200-to- 400-nm -thick Si thin films grown on polycrystalline metal substrates. The Hall mobility increased from 1% to 23% of that in bulk single-crystal Si with decreasing grain mosaic spread from 14° to 2°. For the same range of parameters, a model combining intragrain and grain boundary scattering yielded a decrease of the energy barrier height from 0.1 eV to less than 10-3 eV and an accompanying decrease of trap density from 6Ă 1011 cm-2 to less than 3Ă 1010 cm-2. These results demonstrate that, for polycrystalline Si films, improving the intergrain alignment is an effective and practical alternative to increasing the grain size to achieve enhanced mobility. © 2005 American Institute of Physics
Smart communications network management through a synthesis of distributed intelligence and information
Demands on communications networks to support bundled, interdependent communications services (data, voice, video) are increasing in complexity. Smart network management techniques are required to meet this demand. Such management techniques are envisioned to be based on two main technologies: (i) embedded intelligence; and (ii) up-to-the-millisecond delivery of performance information. This paper explores the idea of delivery of intelligent network management as a synthesis of distributed intelligence and information, obtained through information mining of network performance. © 2008 International Federation for Information Processing
Local Communication Protocols for Learning Complex Swarm Behaviors with Deep Reinforcement Learning
Swarm systems constitute a challenging problem for reinforcement learning
(RL) as the algorithm needs to learn decentralized control policies that can
cope with limited local sensing and communication abilities of the agents.
While it is often difficult to directly define the behavior of the agents,
simple communication protocols can be defined more easily using prior knowledge
about the given task. In this paper, we propose a number of simple
communication protocols that can be exploited by deep reinforcement learning to
find decentralized control policies in a multi-robot swarm environment. The
protocols are based on histograms that encode the local neighborhood relations
of the agents and can also transmit task-specific information, such as the
shortest distance and direction to a desired target. In our framework, we use
an adaptation of Trust Region Policy Optimization to learn complex
collaborative tasks, such as formation building and building a communication
link. We evaluate our findings in a simulated 2D-physics environment, and
compare the implications of different communication protocols.Comment: 13 pages, 4 figures, version 2, accepted at ANTS 201
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