Passive Attack Detection for a Class of Stealthy Intermittent Integrity Attacks

This paper proposes a passive methodology for detecting a class of stealthy intermittent integrity attacks in cyberphysical systems subject to process disturbances and measurement noise.A stealthy intermittent integrity attack strategy is first proposed by modifying a zero-dynamics attack model.The stealthiness of the generated attacks is rigorously investigated under the condition that the adversary does not know precisely the system state values.In order to help detect such attacks,a backward-in-time detection residual is proposed based on an equivalent quantity of the system state change,due to the attack,at a time prior to the attack occurrence time.A key characteristic of this residual is that its magnitude increases every time a new attack occurs.To estimate this unknown residual,an optimal fixed-point smoother is proposed by minimizing a piece-wise linear quadratic cost function with a set of specifically designed weighting matrices.The smoother design guarantees robustness with respect to process disturbances and measurement noise,and is also able to maintain sensitivity as time progresses to intermittent integrity attack by resetting the covariance matrix based on the weighting matrices.The adaptive threshold is designed based on the estimated backward-in-time residual,and the attack detectability analysis is rigorously investigated to characterize quantitatively the class of attacks that can be detected by the proposed methodology.Finally,a simulation example is used to demonstrate the effectiveness of the developed methodology.

通过碳基荧光纳米探针的设计调控其亚细胞定位和生物成像（英文）

碳基荧光纳米探针在生物成像领域展现出诱人的应用前景.本文通过调节合成方法合成了一种磺酸基修饰的石墨烯量子点(SGQDs)荧光探针.该探针呈现出优异的光学和理化性能,如荧光强度高、pH稳定、表面带负电等.研究表明其发光机理主要依赖荧光分子发光机制.与我们之前报道的氨基化量子点A-GQDs和肿瘤细胞核靶向探针GTTN对比,该探针具有良好的生物安全性,可以在相当短的时间内即跨膜进入细胞,而GTTN在正常的体外培养条件下无法进入细胞.为此,我们探究了产生该差异的原因.结果表明,S-GQDs与A-GQDs截然不同的合成原料导致了他们的毒性差异,而S-GQDs的不稳定性则是导致其进入细胞、与GTTN明显不同的主要原因.

Social vocalizations of big-footed myotis(Myotis macrodactylus)during foraging

Acoustic signals play a crucial role in transmitting information and maintaining social stability in gregarious an­imals,especially in echolocating bats,which rely primarily on biological sonar for navigating in the dark.In the context of foraging without relying on tactile,visual or olfactory cues,acoustic signals convey information not only on food but also on ownership and defense of resources.However,studies on such information remain fragmentary.In the present study,we aim to document the social vocal repertoire of Myotis macrodactylus at natural foraging sites.Multiple acoustic analyses and spectrographic classification revealed a rich foraging vo­cal repertoire comprising 6 simple syllables and 2 composites.Discriminant function analyses associated with a subset-validation procedure provided an optimal method to spectrographically classify all recorded sounds into different syllable types.Multidimensional scaling of median values of multiple parameters further confirmed notable differences among these syllables in a 3-D space.In addition,Euclidean distance analysis showed that there were some spectral similarities between specific social vocal syllables and feeding buzzes,which implied a potential jamming role.Altogether,the data indicate that bats at foraging sites under natural conditions used variant social vocalizations with different functions in addition to echolocation calls,providing supporting evi­dence for further work on the function and vocal mechanisms of acoustic communication in mammals.

Quasi-periodic Solutions for the Derivative Nonlinear Schrdinger Equation with Finitely Differentiable Nonlinearities

The authors are concerned with a class of derivative nonlinear Schr¨odinger equation iu_t + u_(xx) + i?f(u, ū, ωt)u_x=0,(t, x) ∈ R × [0, π],subject to Dirichlet boundary condition, where the nonlinearity f(z1, z2, ?) is merely finitely differentiable with respect to all variables rather than analytic and quasi-periodically forced in time. By developing a smoothing and approximation theory, the existence of many quasi-periodic solutions of the above equation is proved.

Separating overlapping bat calls with a bi-directional long short-term memory network

Acquiring clear acoustic signals is critical for the analysis of animal vocalizations.Bioacoustics studies commonly face the problem of overlapping signals,which can impede the structural identification of vocal units,but there is currently no satisfactory solution.This study presents a bi-directional long short-term memory network to separate overlapping echolocation-communication calls of 6 different bat species and reconstruct waveforms.The separation quality was evaluated using 7 temporal-spectrum parameters.All the echolocation pulses and syllables of communication calls in the overlapping signals were separated and parameter comparisons showed no significant difference and negligible deviation between the extracted and original calls.Clustering analysis was conducted with separated echolocation calls from each bat species to provide an example of practical application of the separated and reconstructed calls.The result of clustering analysis showed high corrected rand index(82.79%),suggesting the reconstructed waveforms could be reliably used for species classification.These results demonstrate a convenient and automated approach for separating overlapping calls.The study extends the application of deep neural networks to separate overlapping animal sounds.

Setting up a heart rate alarm limit to decrease oculocardiac reflex during strabismus surgery in children

The aim of this paper is to investigate a method which may decrease the incidence and severity of oculo-cardiac reflex(OCR)without drugs.One hundred and sixty children undergoing strabismus surgery were allo-cated to two groups using double-blind randomization.OCR was defined as a decrease of more than 10%from the baseline heart rate during operation.An alarm sounded and a lamp flashed as soon as OCR occurred in group I,and neither of the above happened in group II.OCR occurred(1.151±0.858)times in group I and(2.287±1.371)times in group II(P<0.05).Heart rate decreased by(23±19)bpm in group I and(35±28)bpm in group II(P<0.05).The duration of OCR in group I and group II was(4.36±4.26)s and(7.62±6.41)s,respectively(P<0.05).The recovery time for group I and group II was(15.36±13.28)s and(32.36±19.57)s,respectively(P<0.05).The numbers of times of interruption were 8 in group I(10%)and 26 in group II(32%)(P<0.01).This method significantly decreased the incidence and severity of OCR during stra-bismus surgery in children.