Learning Fast and Slow: PROPEDEUTICA for Real-time Malware Detection

In this paper, we introduce and evaluate PROPEDEUTICA, a novel methodology and framework for efficient and effective real-time malware detection, leveraging the best of conventional machine learning (ML) and deep learning (DL) algorithms. In PROPEDEUTICA, all software processes in the system start execution subjected to a conventional ML detector for fast classification. If a piece of software receives a borderline classification, it is subjected to further analysis via more performance expensive and more accurate DL methods, via our newly proposed DL algorithm DEEPMALWARE. Further, we introduce delays to the execution of software subjected to deep learning analysis as a way to "buy time" for DL analysis and to rate-limit the impact of possible malware in the system. We evaluated PROPEDEUTICA with a set of 9,115 malware samples and 877 commonly used benign software samples from various categories for the Windows OS. Our results show that the false positive rate for conventional ML methods can reach 20%, and for modern DL methods it is usually below 6%. However, the classification time for DL can be 100X longer than conventional ML methods. PROPEDEUTICA improved the detection F1-score from 77.54% (conventional ML method) to 90.25%, and reduced the detection time by 54.86%. Further, the percentage of software subjected to DL analysis was approximately 40% on average. Further, the application of delays in software subjected to ML reduced the detection time by approximately 10%. Finally, we found and discussed a discrepancy between the detection accuracy offline (analysis after all traces are collected) and on-the-fly (analysis in tandem with trace collection). Our insights show that conventional ML and modern DL-based malware detectors in isolation cannot meet the needs of efficient and effective malware detection: high accuracy, low false positive rate, and short classification time.Comment: 17 pages, 7 figure

In vivo imaging of cell nuclei by photoacoustic microscopy without staining

Ultraviolet photoacoustic microscopy (UVPAM) can image cell nuclei in vivo with high contrast and resolution noninvasively without staining. Here, we used UV light at wavelengths of 210-310 nm for excitation of DNA and RNA to produce photoacoustic waves. We applied the UVPAM to in vivo imaging of cell nuclei in mouse skin, and obtained UVPAM images of the unstained cell nuclei at wavelengths of 245-282 nm as ultrasound gel was used for acoustic coupling. The largest ratio of contrast to noise was found for the images of cell nuclei at a 250 nm wavelength

Optimal ultraviolet wavelength for in vivo photoacoustic imaging of cell nuclei

In order to image noninvasively cell nuclei in vivo without staining, we have developed ultraviolet photoacoustic microscopy (UV-PAM), in which ultraviolet light excites nucleic acids in cell nuclei to produce photoacoustic waves. Equipped with a tunable laser system, the UV-PAM was applied to in vivo imaging of cell nuclei in small animals. We found that 250 nm was the optimal wavelength for in vivo photoacoustic imaging of cell nuclei. The optimal wavelength enables UV-PAM to image cell nuclei using as little as 2 nJ laser pulse energy. Besides the optimal wavelength, application of a wavelength between 245 and 275 nm can produce in vivo images of cell nuclei with specific, positive, and high optical contrast

Pharmacological Effects of Two Novel Bombesin-Like Peptides from the Skin Secretions of Chinese Piebald Odorous Frog (Odorrana schmackeri) and European Edible Frog (Pelophylax kl. esculentus) on Smooth Muscle

Bombesin-like peptides, which were identified from a diversity of amphibian skin secretions, have been demonstrated to possess several biological functions such as stimulation of smooth muscle contraction and regulation of food intake. Here, we report two novel bombesin-like peptides, bombesin-OS and bombesin-PE, which were isolated from Odorrana schmackeri and Pelophylax kl. esculentus, respectively. The mature peptides were identified and structurally confirmed by high performance Scliquid chromatography (HPLC) and tandem mass spectrometry (MS/MS). Subsequently, the effects of these purified chemically-synthetic peptides on smooth muscle were determined in bladder, uterus, and ileum. The synthetic replications were revealed to have significant pharmacological effects on these tissues. The EC50 values of bombesin-OS for bladder, uterus and ileum, were 10.8 nM, 33.64 nM, and 12.29 nM, respectively. Furthermore, compared with bombesin-OS, bombesin-PE showed similar contractile activity on ileum smooth muscle and uterus smooth muscle, but had a higher potency on bladder smooth muscle. The EC50 value of bombesin-OS for bladder was around 1000-fold less than that of bombesin-PE. This suggests that bombesin-OS and bombesin-PE have unique binding properties to their receptors. The precursor of bombesin-OS was homologous with that of a bombesin-like peptide, odorranain-BLP-5, and bombesin-PE belongs to the ranatensin subfamily. We identified the structure of bombesin-OS and bombesin-PE, two homologues peptides whose actions may provide a further clue in the classification of ranid frogs, also in the provision of new drugs for human health

Cognitive Decision-Making in TSP Tasks: The Impact of Line Stylization Features of Point Arrays

The Traveling Salesman Problem (TSP) is a classic NP-hard problem, and research on its cognitive decision-making often focuses on internal factors like memory and experience, while neglecting the influence of the problem's structural characteristics. This study identifies that potential linear features in the TSP point distribution (such as implied paths formed by visual aggregation) may significantly impact human path selection strategies. To test this hypothesis, we propose a method for quantifying the Line Stylization Degree and generate different TSP instances with varying characteristics by introducing disturbances. These are then combined with experimental analysis of participants' decision-making patterns. The results show that participants tend to plan paths along implied lines, and this strategy may reduce cognitive load. The contribution of this paper lies in revealing the shaping role of visual structural features on cognitive decision-making, providing theoretical support for designing human-centered path planning algorithms

Dual-axis illumination for virtually augmenting the detection view of optical-resolution photoacoustic microscopy

Optical-resolution photoacoustic microscopy (OR-PAM) has demonstrated fast, label-free volumetric imaging of optical-absorption contrast within the quasiballistic regime of photon scattering. However, the limited numerical aperture of the ultrasonic transducer restricts the detectability of the photoacoustic waves, thus resulting in incomplete reconstructed features. To tackle the limited-view problem, we added an oblique illumination beam to the original coaxial optical-acoustic scheme to provide a complementary detection view. The virtual augmentation of the detection view was validated through numerical simulations and tissue-phantom experiments. More importantly, the combination of top and oblique illumination successfully imaged a mouse brain in vivo down to 1 mm in depth, showing detailed brain vasculature. Of special note, it clearly revealed the diving vessels that were long missing in images from original OR-PAM

Reflection-mode submicron-resolution in vivo photoacoustic microscopy

Submicron-resolution photoacoustic microscopy (PAM) currently exists only in transmission mode, due to the technical difficulties of combining high numerical-aperture (NA) optical illumination with high NA acoustic detection. The lateral resolution of reflection-mode PAM has not reached <2  μm in the visible light range. Here we develop the first reflection-mode submicron-resolution PAM system with a new compact design. By using a parabolic mirror to focus and reflect the photoacoustic waves, sufficient signals were collected for good sensitivity without distorting the optical focusing. By imaging nanospheres and a resolution test chart, the lateral resolution was measured to be ∼0.5  μm with an optical wavelength of 532 nm, an optical NA of 0.63. The axial resolution was measured at 15 μm. Here the axial resolution was measured by a different experiment with the lateral resolution measurement. But we didn’t describe the details of axial resolution measurement due to space limit. The maximum penetration was measured at ∼0.42  mm in optical-scattering soft tissue. As a comparison, both the submicron-resolution PAM and a 2.4 μm-resolution PAM were used to image a mouse ear in vivo with the same optical wavelength and similar pulse energy. Capillaries were resolved better by the submicron-resolution PAM. Therefore, the submicron-resolution PAM is suitable for in vivo high-resolution imaging, or even subcellular imaging, of optical absorption

Real-time four-dimensional optical-resolution photoacoustic microscopy with Au nanoparticle-assisted subdiffraction-limit resolution

Photoacoustic microscopy (PAM) offers label-free, optical absorption contrast. A high-speed, high-resolution PAM system in an inverted microscope configuration with a laser pulse repetition rate of 100,000 Hz and a stationary ultrasonic transducer was built. Four-dimensional in vivo imaging of microcirculation in mouse skin was achieved at 18 three-dimensional volumes per second with repeated two-dimensional (2D) raster scans of 100 by 50 points. The corresponding 2D B-scan (50 A-lines) frame rate was 1800 Hz, and the one-dimensional A-scan rate was 90,000 Hz. The lateral resolution is 0.23±0.03 μm for Au nanowire imaging, which is 2.0 times below the diffraction limit

Volumetric photoacoustic endoscopy of upper gastrointestinal tract: ultrasonic transducer technology development

We have successfully implemented a focused ultrasonic transducer for photoacoustic endoscopy. The photoacoustic endoscopic probe's ultrasound transducer determines the lateral resolution of the system. By using a focused ultrasonic transducer, we significantly improved the endoscope's spatial resolution and signal-to-noise ratio. This paper describes the technical details of the ultrasonic transducer incorporated into the photoacoustic endoscopic probe and the experimental results from which the transducer's resolution is quantified and the image improvement is validated