382 research outputs found
SHAPFUZZ: Efficient Fuzzing via Shapley-Guided Byte Selection
Mutation-based fuzzing is popular and effective in discovering unseen code
and exposing bugs. However, only a few studies have concentrated on quantifying
the importance of input bytes, which refers to the degree to which a byte
contributes to the discovery of new code. They often focus on obtaining the
relationship between input bytes and path constraints, ignoring the fact that
not all constraint-related bytes can discover new code. In this paper, we
conduct Shapely analysis to understand the effect of byte positions on fuzzing
performance, and find that some byte positions contribute more than others and
this property often holds across seeds. Based on this observation, we propose a
novel fuzzing solution, ShapFuzz, to guide byte selection and mutation.
Specifically, ShapFuzz updates Shapley values (importance) of bytes when each
input is tested during fuzzing with a low overhead, and utilizes contextual
multi-armed bandit to trade off between mutating high Shapley value bytes and
low-frequently chosen bytes. We implement a prototype of this solution based on
AFL++, i.e., ShapFuzz. We evaluate ShapFuzz against ten state-of-the-art
fuzzers, including five byte schedule-reinforced fuzzers and five commonly used
fuzzers. Compared with byte schedule-reinforced fuzzers, ShapFuzz discovers
more edges and exposes more bugs than the best baseline on three different sets
of initial seeds. Compared with commonly used fuzzers, ShapFuzz exposes 20 more
bugs than the best comparison fuzzer, and discovers 6 more CVEs than the best
baseline on MAGMA. Furthermore, ShapFuzz discovers 11 new bugs on the latest
versions of programs, and 3 of them are confirmed by vendors
Further Study On U(1) Gauge Invariance Restoration
To further investigate the applicability of the projection scheme for
eliminating the unphysical divergence due to U(1) gauge invariance
violation, we study the process which possesses
advantages of simplicity and clearness. Our study indicates that the projection
scheme can indeed eliminate the unphysical divergence caused by the
U(1) gauge invariance violation and the scheme can apply to very high energy
region.Comment: Latex, 13 pages, 4 EPS fiure
Genome-wide identification and characterization of HSP gene superfamily in whitefly (Bemisia tabaci) and expression profiling analysis under temperature stress
Heat shock proteins (HSP) are essential molecular chaperones that play important roles in the stress stimulation of insects. Bemisia tabaci, a phloem feeder and
invasive species, can cause extensive crop damage through direct feeding and transmission
of plant viruses. Here we employed comprehensive genomics approaches to identity HSP
superfamily members in the Middle East Asia Minor 1 whitefly genome. In total, we identified 26 Hsp genes, including three Hsp90, 17 Hsp70, one Hsp60 and five sHSP (small
heat shock protein) genes. The HSP gene superfamily of whitefly is expanded compared
with the other five insects surveyed here. The gene structures among the same families
are relatively conserved. Meanwhile, the motif compositions and secondary structures of
BtHsp proteins were predicted. In addition, quantitative polymerase chain reaction analysis showed that the expression patterns of BtHsp gene superfamily were diverse across
different tissues of whiteflies. Most Hsp genes were induced or repressed by thermal stress
(40°C) and cold treatment (4°C) in whitefly. Silencing the expression of BtHsp70-6 significantly decreased the survival rate of whitefly under 45°C. All the results showed the
Hsps conferred thermo-tolerance or cold-tolerance to whiteflies that protect them from
being affected by detrimental temperature conditions. Our observations highlighted the
molecular evolutionary properties and the response mechanism to temperature assaults of
Hsp genes in whitefly
Polo-like kinase 1 regulates mitotic arrest after UV irradiation through dephosphorylation of p53 and inducing p53 degradation
AbstractUltraviolet (UV) irradiation can result in cell cycle arrest. The reactivation of Polo-like kinase 1 (Plk1) is necessary for cell cycle reentry. But the mechanism of how Plk1 regulates p53 in UV-induced mitotic arrest cells remained elusive. Here we find that UV treatment leads HEK293 cells to inverse changes of Plk1 and p53. Over-expression of Plk1 rescue UV-induced mitotic arrest cells by inhibiting p53 activation. Plk1 could also inhibit p53 phosphorylation at Ser15, thus facilitates its nuclear export and degradation. Further examination shows that Plk1, p53 and Cdc25C can form a large complex. Plk1 could bind to the sequence-specific DNA-binding domain of p53 and active Cdc25C by hyperphosphorylation. These results hypothesize that Plk1 and Cdc25C participate in recovery the mitotic arrest through binding to the different domain of p53. Cdc25C may first be actived by Plk1, and then its phosphatase activity makes p53 dephosphorylated at Ser15
A controllable superconducting electromechanical oscillator with a suspended membrane
We fabricate a microscale electromechanical system, in which a suspended
superconducting membrane, treated as a mechanical oscillator, capacitively
couples to a superconducting microwave resonator. As the microwave driving
power increases, nonmonotonic dependence of the resonance frequency of the
mechanical oscillator on the driving power has been observed. We also
demonstrate the optical switching of the resonance frequency of the mechanical
oscillator. Theoretical models for qualitative understanding of our
experimental observations are presented. Our experiment may pave the way for
the application of a mechanical oscillator with its resonance frequency
controlled by the electromagnetic and/or optical fields, such as a
microwave-optical interface and a controllable element in a
superqubit-mechanical oscillator hybrid system.Comment: 8 pages,4 figure
Supramolecular assemblies constructed from inverted cucurbit[7]uril and lanthanide cations: synthesis, structure and sorption properties
The interaction of a series of lanthanide cations (Ln³⁺) with inverted cucurbit[7]uril (iQ[7]) in the presence of [ZnCl₄]²⁻ anions as a structure-directing agent have been investigated. Single-crystal X-ray diffraction analysis has revealed that the [ZnCl₄]²⁻ anions surround the iQ[7] molecules via the outer surface interactions of iQ[7]. This results in the formation of honeycomb-like frameworks, and ultimately linear supramolecular chains of iQ[7] in which Ln³⁺ cations occupy voids within the framework. Moreover, these iQ[7]/Ln³⁺-based supramolecular assemblies exhibit excellent thermal stability as well as permanent porosity, and in one case screening revealed a high CH₃OH uptake capacity compared with other porous organic materials assembled solely through hydrogen bonding under ambient conditions
Composition and Performance of Nanostructured Zirconium Titanium Conversion Coating on Aluminum-Magnesium Alloys
Nanostructured conversion coating of Al-Mg alloy was obtained via the surface treatment with zirconium titanium salt solution at 25°C for 10 min. The zirconium titanium salt solution is composed of tannic acid 1.00 g·L−1, K2ZrF6 0.75 g·L−1, NaF 1.25 g·L−1, MgSO4 1.0 g/L, and tetra-n-butyl titanate (TBT) 0.08 g·L−1. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrum (FT-IR) were used to characterize the composition and structure of the obtained conversion coating. The morphology of the conversion coating was obtained by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Results exhibit that the zirconium titanium salt conversion coating of Al-Mg alloy contains Ti, Zr, Al, F, O, Mg, C, Na, and so on. The conversion coating with nm level thickness is smooth, uniform, and compact. Corrosion resistance of conversion coating was evaluated in the 3.5 wt.% NaCl electrolyte through polarization curves and electrochemical impedance spectrum (EIS). Self-corrosion current density on the nanostructured conversion coating of Al-Mg alloy is 9.7×10-8A·cm-2, which is only 2% of that on the untreated aluminum-magnesium alloy. This result indicates that the corrosion resistance of the conversion coating is improved markedly after chemical conversion treatment
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