594 research outputs found
Checking Interaction-Based Declassification Policies for Android Using Symbolic Execution
Mobile apps can access a wide variety of secure information, such as contacts
and location. However, current mobile platforms include only coarse access
control mechanisms to protect such data. In this paper, we introduce
interaction-based declassification policies, in which the user's interactions
with the app constrain the release of sensitive information. Our policies are
defined extensionally, so as to be independent of the app's implementation,
based on sequences of security-relevant events that occur in app runs. Policies
use LTL formulae to precisely specify which secret inputs, read at which times,
may be released. We formalize a semantic security condition, interaction-based
noninterference, to define our policies precisely. Finally, we describe a
prototype tool that uses symbolic execution to check interaction-based
declassification policies for Android, and we show that it enforces policies
correctly on a set of apps.Comment: This research was supported in part by NSF grants CNS-1064997 and
1421373, AFOSR grants FA9550-12-1-0334 and FA9550-14-1-0334, a partnership
between UMIACS and the Laboratory for Telecommunication Sciences, and the
National Security Agenc
Brazilian Bidens pilosa Linne´ yields fraction containing quercetin-derived flavonoid with free radical scavenger activity and hepatoprotective effects
Bidens pilosa is a plant used by Amazonian and Asian folks for some hepatopathies. The hydroethanol crude extract and three fractions were assessed for antioxidant and hepatoprotective effects. Higher levels of scavenger activity on the 1,1-diphenyl-2-picrylhydrazyl radical, inhibition of deoxyribose oxidation and lipid peroxidation in vitro were detected for the ethyl acetate fraction (IC50∼4.3-32.3 mg/ml) followed by the crude extract (IC50∼14.2-98.0 mg/ml). The ethyl acetate fraction, again followed by the crude extract, showed high contents of total soluble polyphenols (3.6±0.2 and 2.1±0.2 GAE/mg, respectively) and presence of a quercetin-derived flavonoid identified as quercetin 3,3′-dimethyl ether 7-Ο-β-D-glycopyranoside. Both products were assayed for hepatoprotector effects against CCl4-induced liver injury in mice. Markers of oxidative stress and hepatic injury were evaluated. The results showed that the 10-day pretreatments (15 mg/kg, p.o.) protected the livers against injury by blocking CCl4-induced lipid peroxidation and protein carbonylation and the DNA fragmentation was decreased (∼60%). The pretreatments avoided the loss of the plasma ferric reducing/antioxidant power and the elevation of serum transaminases and lactate dehydrogenase activities. The results suggest that the main constituents responsible for the hepatoprotective effects with free radical scavenger power associated are well extracted by performing fractionation with ethyl acetate. The findings support the Brazilian traditional use of this plant and justify further evaluations for the therapeutic efficacy and safety of the constituents of the ethyl acetate fraction to treat some liver diseases.Keywords: Bidens pilosa L.; hydroethanol maceration; ethyl acetate fractionation; free radical scavenger; hepatoprotection; CCl4 toxicit
Realizing Omega-regular Hyperproperties
We studied the hyperlogic HyperQPTL, which combines the concepts of trace
relations and -regularity. We showed that HyperQPTL is very expressive,
it can express properties like promptness, bounded waiting for a grant,
epistemic properties, and, in particular, any -regular property. Those
properties are not expressible in previously studied hyperlogics like HyperLTL.
At the same time, we argued that the expressiveness of HyperQPTL is optimal in
a sense that a more expressive logic for -regular hyperproperties would
have an undecidable model checking problem. We furthermore studied the
realizability problem of HyperQPTL. We showed that realizability is decidable
for HyperQPTL fragments that contain properties like promptness. But still, in
contrast to the satisfiability problem, propositional quantification does make
the realizability problem of hyperlogics harder. More specifically, the
HyperQPTL fragment of formulas with a universal-existential propositional
quantifier alternation followed by a single trace quantifier is undecidable in
general, even though the projection of the fragment to HyperLTL has a decidable
realizability problem. Lastly, we implemented the bounded synthesis problem for
HyperQPTL in the prototype tool BoSy. Using BoSy with HyperQPTL specifications,
we have been able to synthesize several resource arbiters. The synthesis
problem of non-linear-time hyperlogics is still open. For example, it is not
yet known how to synthesize systems from specifications given in branching-time
hyperlogics like HyperCTL.Comment: International Conference on Computer Aided Verification (CAV 2020
Arachnidism, scorpionism and ophidism in Ouro Preto Municipality, Minas Gerais State, Brazil
Abstract: INTRODUCTION This retrospective study shows the profile of arachnidism, ophidism, and scorpionism in the Ouro Preto Municipality, Brazil, from January 2007 to December 2013. METHODS The data were gathered from forms of the Epidemiological Surveillance Sector of the town's Health's Municipal Secretary. RESULTS Of the 412 envenomations, 308 were caused by spiders, 78 by scorpions, and 26 by snakes. The highest number of incidents involved people aged 20-34 years. Females were more affected than males. There were no reports of death. CONCLUSIONS The results show that envenomations caused by spiders, scorpions and snakes have decreased in recent years
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The influence of the accessory genome on bacterial pathogen evolution
Bacterial pathogens exhibit significant variation in their genomic content of virulence factors. This reflects the abundance of strategies pathogens evolved to infect host organisms by suppressing host immunity. Molecular arms-races have been a strong driving force for the evolution of pathogenicity, with pathogens often encoding overlapping or redundant functions, such as type III protein secretion effectors and hosts encoding ever more sophisticated immune systems. The pathogens’ frequent exposure to other microbes, either in their host or in the environment, provides opportunities for the acquisition or interchange of mobile genetic elements. These DNA elements accessorise the core genome and can play major roles in shaping genome structure and altering the complement of virulence factors. Here, we review the different mobile genetic elements focusing on the more recent discoveries and highlighting their role in shaping bacterial pathogen evolution
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