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1. An STL-Based Formulation of Resilience in Cyber-Physical Systems

   https://doi.org/10.1007/978-3-031-15839-1_7  

   Chen, Hongkai; Lin, Shan; Smolka, Scott A.; Paoletti, Nicola (August 2022, Formal Modeling and Analysis of Timed Systems)

   Bogomolov, Sergiy; Parker, David (Ed.)

   Resiliency is the ability to quickly recover from a violation and avoid future violations for as long as possible. Such a property is of fundamental importance for Cyber-Physical Systems (CPS), and yet, to date, there is no widely agreed-upon formal treatment of CPS resiliency. We present an STL-based framework for reasoning about resiliency in CPS in which resiliency has a syntactic characterization in the form of an STL-based Resiliency Specification (SRS). Given an arbitrary STL formula φ, time bounds α and β, the SRS of φ, Rα,β (φ), is the STL formula ¬φU[0,α]G[0,β)φ, specifying that recovery from a violation of φ occur within time α (recoverability), and subsequently that φ be maintained for duration β (durability). These R-expressions, which are atoms in our SRS logic, can be combined using STL operators, allowing one to express composite resiliency specifications, e.g., multiple SRSs must hold simultaneously, or the system must eventually be resilient. We define a quantitative semantics for SRSs in the form of a Resilience Satisfaction Value (ReSV) function r and prove its soundness and completeness w.r.t. STL’s Boolean semantics. The r-value for Rα,β (φ) atoms is a singleton set containing a pair quantifying recoverability and durability. The r-value for a composite SRS formula results in a set of non-dominated recoverability-durability pairs, given that the ReSVs of subformulas might not be directly comparable (e.g., one subformula has superior durability but worse recoverability than another). To the best of our knowledge, this is the first multi-dimensional quantitative semantics for an STL-based logic. Two case studies demonstrate the practical utility of our approach. https://doi.org/10.1007/978-3-031-15839-1_7 

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2. 4Pi stimulated Raman scattering for label-free super-resolution chemical imaging

   https://doi.org/10.1126/sciadv.aec0523  

   Kim, Jonathan I; Ellsworth, Zachary; Dunnington, Erin L; Wong, Brian S; Mehta, Nidhi R; Zensho, Chisa; Fu, Dan (January 2026, Science Advances)

   Super-resolution fluorescence microscopy has transformed biological imaging beyond the diffraction limit. However, many biomolecules, nanostructures, drug molecules, and metabolites cannot be easily tagged, requiring a label-free imaging approach. Stimulated Raman scattering (SRS) microscopy is a powerful platform for super-resolution label-free imaging, yet current super-resolution SRS approaches rely on photoswitching, saturation, or sample expansion, which are limited by labeling, photodamage, or signal dilution, respectively. Here, we combine SRS with 4Pi interferometry to enhance axial resolution nearly sevenfold. We report on improvements in imaging sensitivity and axial resolution using 80-nanometer polystyrene beads. Harnessing the improved axial resolution, we demonstrate super-resolution 4Pi-SRS imaging in resolving small lipid droplet structures in mammalian cells and lipid membranes inEscherichia colicells. Because 4Pi-SRS uses interferometry to improve axial resolution, it is orthogonal to all previous super-resolution SRS techniques; thus, it is straightforward to integrate it with existing methods to achieve much higher resolution chemical imaging than previously possible. 

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3. Raman scattering applied to human breath analysis

   https://doi.org/10.1016/j.trac.2024.117791  

   Arachchige, Charuka Muktha; Muller, Andreas (August 2024, TrAC Trends in Analytical Chemistry)

   The chemical composition of exhaled human breath can be strongly correlated to medical conditions such as lung cancer or gastrointestinal diseases. To establish these correlations and, most importantly, to use them in diagnostics, chemical gas detection needs to be performed at trace concentrations, typically at parts-per-million (ppm) levels or below, for many compounds simultaneously. Traditional methods such as gas chromatography, a workhorse in scientific laboratories, is ill-suited for the fast, inexpensive point-of-care diagnostics that would be needed to build statistically-meaningful ensembles over large populations. With the increasing availability and decreasing cost of high power diode lasers and of uncooled CMOS cameras, spontaneous Raman spectroscopy (SRS), a vibrational molecular fingerprinting tool, is emerging as an economic alternative. Although gas SRS scattering cross sections are only on the order of 10$$^{-31}$$ cm$^2$/sr, considerable progress in the development of enhancement techniques has been made over the past decade. The purpose of this work is to review SRS enhancement approaches in the context of established human breath tests, and to provide a comparison with alternatives. Already, numerous trace gases such as H$$_2$$, CH$$_4$$, $$^{13}$$CO$$_2$$, and volatile organic compounds like acetone can be rapidly quantified in breath at concentrations below 1 ppm with SRS. With improvements in resolution and design of enhancement systems, SRS-based sensors could be scalably deployed in, e.g., pharmacies, and non-invasively screen for dozens of analytes at the parts-per-billion level. 

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4. Closing the Wearable Gap—Part V: Development of a Pressure-Sensitive Sock Utilizing Soft Sensors

   https://doi.org/10.3390/s20010208  

   Luczak, Tony; Burch V, Reuben F.; Smith, Brian K.; Carruth, Daniel W.; Lamberth, John; Chander, Harish; Knight, Adam; Ball, J.E.; Prabhu, R.K. (January 2020, Sensors)

   The purpose of this study was to evaluate the use of compressible soft robotic sensors (C-SRS) in determining plantar pressure to infer vertical and shear forces in wearable technology: A ground reaction pressure sock (GRPS). To assess pressure relationships between C-SRS, pressure cells on a BodiTrakTM Vector Plate, and KistlerTM Force Plates, thirteen volunteers performed three repetitions of three different movements: squats, shifting center-of-pressure right to left foot, and shifting toes to heels with C-SRS in both anterior–posterior (A/P) and medial–lateral (M/L) sensor orientations. Pearson correlation coefficient of C-SRS to BodiTrakTM Vector Plate resulted in an average R-value greater than 0.70 in 618/780 (79%) of sensor to cell comparisons. An average R-value greater than 0.90 was seen in C-SRS comparison to KistlerTM Force Plates during shifting right to left. An autoregressive integrated moving average (ARIMA) was conducted to identify and estimate future C-SRS data. No significant differences were seen in sensor orientation. Sensors in the A/P orientation reported a mean R2 value of 0.952 and 0.945 in the M/L sensor orientation, reducing the effectiveness to infer shear forces. Given the high R values, the use of C-SRSs to infer normal pressures appears to make the development of the GRPS feasible. 

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5. Electron and hole surface roughness scattering-limited mobilities in oxygen-inserted (OI) Si channel

   https://doi.org/10.1063/5.0316691  

   Magendar, Vikram; Chen, Yi-Ann; Lu, Albert; Kang, Donghun; Connelly, Daniel; Hytha, Marek; Takeuchi, Hideki; Mears, Robert; Wong, Hiu Yung (March 2026, Journal of Applied Physics)

   The electron and hole surface roughness scattering (SRS)-limited mobilities, deconvolved from 4.2 K measurements, were compared between oxygen-inserted (OI) and control Si channel for n- and pMOSFETs. It was found that electron SRS-limited mobility in the OI-Si channel is 55% higher, whereas hole SRS-limited mobility is comparable to the control. To elucidate the difference, the Si/SiO2 interface roughness and the nanoscale thickness variation of the gate oxide were analyzed in detail, via high-resolution transmission electron microscopy images, and fed into numerical calculation of the SRS-limited mobility. The power spectral densities (PSDs) based on the Yule–Walker autoregressive model revealed that the OI-Si has a smaller surface roughness at low-frequency components, corresponding to the electron Fermi surface energy level. In contrast, surface roughness improvement was found to be less at a higher frequency region of the PSDs corresponding to the hole Fermi surface energy level. Furthermore, an oxygen tracer experiment identified a dynamic exchange process between the Si/SiO2 interface and the OI-Si layer, suggesting an opportunity for improving hole SRS-limited mobility in the OI-Si channel via tuning post-oxidation thermal process steps. 

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