Active Modes Research Articles

Tracking nuclear motion in single-molecule magnets using femtosecond X-ray absorption spectroscopy

The development of new data storage solutions is crucial for emerging digital technologies. Recently, all-optical magnetic switching has been achieved in dielectrics, proving to be faster than traditional methods. Despite this, single-molecule magnets (SMMs), which are an important class of magnetic materials due to their nanometre size, remain underexplored for ultrafast photomagnetic switching. Herein, we report femtosecond time-resolved K-edge X-ray absorption spectroscopy (TR-XAS) on a Mn(III)-based trinuclear SMM. Exploiting the elemental specificity of XAS, we directly track nuclear dynamics around the metal ions and show that the ultrafast dynamics upon excitation of a crystal-field transition are dominated by a magnetically active Jahn-Teller mode. Our results, supported by simulations, reveal minute bond length changes from 0.01 to 0.05 Å demonstrating the sensitivity of the method. These geometrical changes are discussed in terms of magneto-structural relationships and consequently our results illustrate the importance of TR-XAS for the emerging area of ultrafast molecular magnetism.

Combined Computational and Experimental Study Reveals Complex Mechanistic Landscape of Brønsted Acid-Catalyzed Silane-Dependent P═O Reduction.

The reaction mechanism of Brønsted acid-catalyzed silane-dependent P═O reduction has been elucidated through combined computational and experimental methods. Due to its remarkable chemo- and stereoselective nature, the Brønsted acid/silane reduction system has been widely employed in organophosphine-catalyzed transformations involving P(V)/P(III) redox cycle. However, the full mechanistic profile of this type of P═O reduction has yet to be clearly established to date. Supported by both DFT and experimental studies, our research reveals that the reaction likely proceeds through mechanisms other than the widely accepted "dual activation mode by silyl ester" or "acid-mediated direct P═O activation" mechanism. We propose that although the reduction mechanisms may vary with the substitution patterns of silane species, Brønsted acid generally activates the silane rather than the P═O group in transition structures. The proposed activation mode differs significantly from that associated with traditional Brønsted acid-catalyzed C═O reduction. The uniqueness of P═O reduction originates from the dominant Si/O═P orbital interactions in transition structures rather than the P/H-Si interactions. The comprehensive mechanistic landscape provided by us will serve as a guidance for the rational design and development of more efficient P═O reduction systems as well as novel organophosphine-catalyzed reactions involving P(V)/P(III) redox cycle.

Vigil AI Assemble Leveraging Ensemble Technique for Enhanced Detection of Multi-Converter Synchronous Active Islanding Mode in Hybrid Power Distribution Systems

The increasing complexity of contemporary power distribution networks and the necessity to incorporate renewable energy sources have led to the rise in popularity of hybrid power distribution systems. A significant challenge for such systems is the reliable identification of multi-converter synchronous islanding mode, wherein numerous converters operate in synchronous islanded situations. Using state-of-the-art artificial intelligence ensemble techniques, we introduce "Vigil AI Assemble," a novel approach to detecting multi-converter synchronous islanding modes in hybrid power distribution systems. The proposed method enhances the precision and robustness of islanding situation recognition by combining various AI algorithms, each with its own distinct properties. By combining several AI-based techniques, the ensemble method can analyze system properties, waveform data, and communication in real-time.

Exploration of a machine learning approach for diagnosing sarcopenia among Chinese community-dwelling older adults using sEMG-based data

BackgroundIn the practical application of sarcopenia screening, there is a need for faster, time-saving, and community-friendly detection methods. The primary purpose of this study was to perform sarcopenia screening in community-dwelling older adults and investigate whether surface electromyogram (sEMG) from hand grip could potentially be used to detect sarcopenia using machine learning (ML) methods with reasonable features extracted from sEMG signals. The secondary aim was to provide the interpretability of the obtained ML models using a novel feature importance estimation method.MethodsA total of 158 community-dwelling older residents (≥ 60 years old) were recruited. After screening through the diagnostic criteria of the Asian Working Group for Sarcopenia in 2019 (AWGS 2019) and data quality check, participants were assigned to the healthy group (n = 45) and the sarcopenic group (n = 48). sEMG signals from six forearm muscles were recorded during the hand grip task at 20% maximal voluntary contraction (MVC) and 50% MVC. After filtering recorded signals, nine representative features were extracted, including six time-domain features plus three time-frequency domain features. Then, a voting classifier ensembled by a support vector machine (SVM), a random forest (RF), and a gradient boosting machine (GBM) was implemented to classify healthy versus sarcopenic participants. Finally, the SHapley Additive exPlanations (SHAP) method was utilized to investigate feature importance during classification.ResultsSeven out of the nine features exhibited statistically significant differences between healthy and sarcopenic participants in both 20% and 50% MVC tests. Using these features, the voting classifier achieved 80% sensitivity and 73% accuracy through a five-fold cross-validation. Such performance was better than each of the SVM, RF, and GBM models alone. Lastly, SHAP results revealed that the wavelength (WL) and the kurtosis of continuous wavelet transform coefficients (CWT_kurtosis) had the highest feature impact scores.ConclusionThis study proposed a method for community-based sarcopenia screening using sEMG signals of forearm muscles. Using a voting classifier with nine representative features, the accuracy exceeds 70% and the sensitivity exceeds 75%, indicating moderate classification performance. Interpretable results obtained from the SHAP model suggest that motor unit (MU) activation mode may be a key factor affecting sarcopenia.

The interplay of topology and antiferromagnetic order in two-dimensional van der Waals crystals of (Ni x Fe1−x )2P2S6

The Mermin–Wagner theorem forbids spontaneous symmetry breaking of spins in one/two-dimensional (2D) systems at a finite temperature and rules out the stabilization of this ordered state. However, it does not apply to all types of phase transitions in low dimensions, such as the topologically ordered phase rigorously shown by Berezinskii–Kosterlitz–Thouless (BKT) and experimentally realized in very limited systems such as superfluids and superconducting thin films. Quasi-2D van der Waals magnets provide an ideal platform to investigate the fundamentals of low-dimensional magnetism. We explored the quasi-2D honeycomb antiferromagnetic single crystals of (Ni x Fe1−x )2P2S6 (x = 1, 0.7, 0.5, 0.3, and 0) using in-depth temperature-dependent Raman measurements supported by first-principles calculations of the phonon frequencies. Quite surprisingly, we observed renormalization of the phonon modes much below the long-range magnetic ordered temperature attributed to the topological ordered state, namely the BKT phase, which is also found to change as a function of doping. The extracted critical exponent of the order-parameter (spin–spin correlation length, ξ(T) ) evinces the signature of a topologically active state driven by vortex–antivortex excitations. As a function of doping, a tunable transition from paramagnetic to antiferromagnetic ordering is shown via phonons reflected in the strong renormalization of the self-energy parameters of the Raman active phonon modes. The extracted exchange parameter (J) is found to vary by ∼100% by increasing the value of doping, ranging from ∼6 meV (for x = 0.3) to 13 meV (for x = 1).

Boron catalysis in a designer enzyme.

Enzymes play an increasingly important role in improving the benignity and efficiency of chemical production, yet the diversity of their applications lags heavily behind chemical catalysts as a result of the relatively narrow range of reaction mechanisms of enzymes. The creation of enzymes containing non-biological functionalities facilitates reaction mechanisms outside nature's canon and paves the way towards fully programmable biocatalysis1-3. Here we present a completely genetically encoded boronic-acid-containing designer enzyme with organocatalytic reactivity not achievable with natural or engineered biocatalysts4,5. This boron enzyme catalyses the kinetic resolution of hydroxyketones by oxime formation, in which crucial interactions with the protein scaffold assist in the catalysis. A directed evolution campaign led to a variant with natural-enzyme-like enantioselectivities for several different substrates. The unique activation mode of the boron enzyme was confirmed using X-ray crystallography, high-resolution mass spectrometry (HRMS) and 11B NMR spectroscopy. Our study demonstrates that genetic-code expansion can be used to create evolvable enantioselective enzymes that rely on xenobiotic catalytic moieties such as boronic acids and access reaction mechanisms not reachable through catalytic promiscuity of natural or engineered enzymes.

Development of the Bipolar Junction Transistor Diagnostic Test (BJTDT) to explore the second-year undergraduate Myanmar electronic and Thai electrical engineering students’ understanding of BJT working principles and applications

ABSTRACT A bipolar junction transistor (BJT) and its operation are fundamental concepts for the understanding of power electronics (industrial electronics), transistor-transistor logic (TTL), electronic switching, and signal amplification in modern electronics. Previous research showed that non-major engineering, computer, electronic, and electrical engineering students could not understand the basic concepts involved in a BJT. This paper describes the development of a two-tier diagnostic test, the test’s administration, limitations, the participants’ detailed context, and findings from a study that explores Myanmar and Thai second-year undergraduate students’ understanding of BJT working principles and applications. The results revealed that many students in both countries had the same alternative conceptions about collector current in each operation mode of the BJT. Some alternative conceptions differ from the previous research, such as a) the collector current does not depend on the base current in cut-off mode, and b) changing the collector current does not depend on the base current in active mode, but it depends on the collector supply voltage. These research findings provide valuable information and instruments for teachers to insight, prevent, and correct the alternative conceptions proposed by students.

Quantifying time spent outdoors: A versatile method using any type of global positioning system (GPS) and accelerometer devices.

Spending time outdoors is associated with increased time spent in physical activity, lower chronic disease risk, and wellbeing. Many studies rely on self-reported measures, which are prone to recall bias. Other methods rely on features and functions only available in some GPS devices. Thus, a reliable and versatile method to objectively quantify time spent outdoors is needed. This study sought to develop a versatile method to classify indoor and outdoor (I/O) GPS data that can be widely applied using most types of GPS and accelerometer devices. To develop and test the method, five university students wore an accelerometer (ActiGraph wGT3X-BT) and a GPS device (Canmore GT-730FL-S) on an elastic belt at the right hip for two hours in June 2022 and logged their activity mode, setting, and start time via activity diaries. GPS trackers were set to collect data every 5 seconds. A rule-based point cluster-based method was developed to identify indoor, outdoor, and in-vehicle time. Point clusters were detected using an application called GPSAS_Destinations and classification were done in R using accelerometer lux, building footprint, and park location data. Classification results were compared with the submitted activity diaries for validation. A total of 7,006 points for all participants were used for I/O classification analyses. The overall I/O GPS classification accuracy rate was 89.58% (Kappa = 0.78), indicating good classification accuracy. This method provides reliable I/O clarification results and can be widely applied using most types of GPS and accelerometer devices.

Transesterification of Dimethyl Carbonate with Ethanol Catalyzed by Guanidine: A Theoretical Analysis.

Density-functional theory (DFT) was performed to investigate the mechanistic features of different guanidine-based catalysts, namely, 1,1,3,3-tetramethyl guanidine (TMG) and 1,5,7-triaza-bicyclo-[4.4.0]dec-5-ene (TBD), for the transesterification reaction of dimethyl carbonate (DMC) with ethanol (EtOH). Different possible pathways were suggested in which these catalysts act as either nucleophile or base within a homogeneous system. The DFT results allowed not only the study of the thermochemistry aspects of all elementary reactions featured in the two different activation modes but also the accurate calculation of the free energy barriers for each case. Our findings showed that the catalyzed reaction proceeded through simultaneous activation of DMC and EtOH, facilitated by hydrogen bonding for both catalysts. This feature led to the formation of a stable intermediate with a relatively low free energy barrier. TBD exhibited a potentially more efficient mechanism, owing to its planar structure and dual-activation mode. The free energy barrier of the rate-limiting step, identified as the formation of a zwitterionic complex, then declined by approximately 50% when compared with the reaction without catalysts. Overall, the DFT approach provides good insight into the reactivity of both catalysts and helps to find possibilities for further enhancing the mechanistic features of both catalysts for this type of transesterification reaction.

Conserved spin operator of Dirac’s theory in spatially flat FLRW space-times

New conserved spin and orbital angular momentum operators of Dirac’s theory on spatially flat FLRW space-times are proposed generalizing thus the recent results concerning the role of Pryce’s spin operator in the flat case (Cotăescu in Eur Phys J C, 82, 1073, 2022). These operators split the conserved total angular momentum generating the new spin and orbital symmetries that form the rotations of the isometry groups. The new spin operator is defined and studied in active mode with the help of a suitable spectral representation giving its Fourier transform. Moreover, in the same manner is defined the operator of the fermion polarization. The orbital angular momentum is derived in passive mode using a new method, inspired by Wigner’s theory of induced representations, but working properly only for global rotations. In this approach the quantization is performed finding that the one-particle spin and orbital angular momentum operators have the same form in any FLRW spacetime regardless their concrete geometries given by various scale factors.

Abstract PO1-13-04: Distinct immune signatures discriminate between patients defined as exceptional survivors of metastatic breast cancer compared to those with rapidly progressing treatment resistant breast cancers

Abstract Background: "Atypical responders" can encompass three sub- categories of patients: "exceptional responders" (those with an unusually favourable treatment response), "rapid progressors" (unusually poor or no response), and "exceptional/long-term survivors" (outlived initial prognosis). Here, we aim to investigate the drivers of immune surveillance mechanisms (local, lymphoid and peripheral) and the nature of immunological tumour recognition in exceptional survivors of stage 4 metastatic disease following standard-of-care chemo- and targeted therapies. Methods: We conducted a complementary multi-platform immune profiling study to define differences in the phenotypic immune landscape including mass-spectrometry-based proteomics on peripheral blood mononuclear cells (PBMCs), multiplex cytokine profiling of patient serum, and high-dimensional flow cytometry on whole blood samples. By staining 500μl of whole blood using 2 panels, 353 immune-cell-related parameters were obtained for comparisons among the following groups: "exceptional survivors," "exceptional responders," "rapid progressors," "non-exceptional metastatic patients," "early breast cancer patients," and "healthy volunteers". Patients were matched for age, breast cancer receptor status, and sites of metastases where possible. Results: Preliminary analysis of serum biomarkers and proteome of the PBMCs of the exceptional survivors showed elevated levels of NK-cell-related proteins such as KCTD10 and RBBP7. Flow cytometry analysis revealed the presence of increased activated CD56dim NK cells, CD56bright NK cells, and central memory (CM) (CD45RA-CD27+) CD8 T cells in both the exceptional survivors and the rapid progressors. However, expression of CD25 appears to be the main mode of activation in rapid progressors compared with increased NKG2D expression in exceptional survivors. Additionally, activation of the unconventional gd T cells was evident in both groups with terminally differentiated effector memory cells re-expressing CD45RA (TEMRA) Vd1 cell predominating in the exceptional survivors. In the rapid progressors, the increased CD25+ TEMRA Vd2 cells coupled with elevated serum IL-17A and IL-1b suggest their ability to generate IL-17. Th2 cytokines, IL-5 and IL-13 were also enriched in rapid progressors and concomitant increase in CD25+ Th2 cells reveals a strong Th2-driven immune signature in these patients. Finally increased CD86+ atypical double negative (DN) B cells, mostly comprised of the DN2 subset were also significantly enriched in the rapid progressors compared to the exceptional survivors where DN1 B cells were prevalent. Conclusion: The multi-platform approach to investigating immune responses present in atypical responders has identified several distinct immunophenotypes in which the extreme outliers differ in their potential immune surveillance mechanisms. Functional validation of these findings through activation and cytotoxicity assays is currently underway and future work aims to understand the spatial biology of these circulating immune cells within the context of their primary tumours, metastases, and lymph nodes. Citation Format: Helen Kakkassery, Thanussuyah Alaguthurai, Zuza Kozik, Paul Buckley, Ruifang Lu, Esme Carpenter, Rosalind Graham, Gheed Alhity, Farhana Hossain, Sadiyah Mukhtar, Syed Haider, Jyoti Choudhary, Sheeba Irshad. Distinct immune signatures discriminate between patients defined as exceptional survivors of metastatic breast cancer compared to those with rapidly progressing treatment resistant breast cancers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-13-04.

Improving interest in public, active, and shared travel modes through nudging interventions

Nudging is a popular approach to changing behavior by designing interventions to encourage, for instance, sustainable or healthy actions without necessarily limiting freedom of choice. Nudging could show particular potential in changing travel behavior by providing governments with softer policy options to reduce the negative impacts of private vehicles in urban areas. This study examines the efficacy of nudging in changing interest in using public transport, active modes, and carsharing in Flanders, Belgium (n = 292), focusing on moral nudges, highlighting individual and social benefits, and norm nudges, using social pressure to promote appropriate behavior, through independent and paired sample t-tests, ANOVA mean-comparison tests, and multiple linear regression models. Results indicate that moral nudging is effective overall, but particularly for improving interest in carsharing, potentially providing an option for individuals wanting to make environmentally and socially conscious choices without drastically changing their lifestyles. Norm nudging was effective for public transport and especially active travel, indicating that mobility cultures and social acceptance are important to these modes. Attitudes toward public transport and carsharing were important to nudge susceptibility. Women might have greater concerns about making environmentally moral choices, resulting in higher moral nudge susceptibility, particularly for active travel, and trips taken with companions might be more easily swayed toward active modes. Those with greater time flexibility who are younger might be a target group for carsharing, especially when influenced by moral arguments, while older retired and full-time employed individuals may not be willing to give up their private cars and carsharing may not be practical for families with children. Nudging might be effective in changing travel behavior in conjunction with other policy measures to promote sustainable and healthy transport, ideally through a nudge unit to test, advise, and implement these subtle nudges. Further, the location, quality of transport services, and geographical density of cities are crucial aspects regarding the effectiveness of nudges in real-life scenarios.

An Atraumatic Mock Loop for Realistic Hemocompatibility Assessment of Blood Pumps.

Conventional mock circulatory loops (MCLs) cannot replicate realistic hemodynamic conditions without inducing blood trauma. This constrains in-vitro hemocompatibility examinations of blood pumps to static test loops that do not mimic clinical scenarios. This study aimed at developing an atraumatic MCL based on a hardware-in-the-loop concept (H-MCL) for realistic hemocompatibility assessment. The H-MCL was designed for 450 ± 50 ml of blood with the polycarbonate reservoirs, the silicone/polyvinyl-chloride tubing, and the blood pump under investigation as the sole blood-contacting components. To account for inherent coupling effects a decoupling pressure control was derived by feedback linearization, whereas the level control was addressed by an optimization task to overcome periodic loss of controllability. The HeartMate 3 was showcased to evaluate the H-MCL's accuracy at typical hemodynamic conditions. To verify the atraumatic properties of the H-MCL, hemolysis (bovine blood, n = 6) was evaluated using the H-MCL in both inactive (static) and active (minor pulsatility) mode, and compared to results achieved in conventional loops. Typical hemodynamic scenarios were replicated with marginal coupling effects and root mean square error (RMSE) below 1.74 ± 1.37 mmHg while the fluid level remained within ±4% of its target value. The normalized indices of hemolysis (NIH) for the inactive H-MCL showed no significant differences to conventional loops ( ∆NIH = -1.6 mg/100 L). Further, no significant difference was evident between the active and inactive mode in the H-MCL ( ∆NIH = +0.3 mg/100 L). Collectively, these findings indicated the H-MCL's potential for in-vitro hemocompatibility assessment of blood pumps within realistic hemodynamic conditions, eliminating inherent setup-related risks for blood trauma.

Electroacupuncture modulates abnormal brain connectivity after ischemia reperfusion injury in rats: A graph theory-based approach.

Electroacupuncture (EA) has been shown to facilitate brain plasticity-related functional recovery following ischemic stroke. The functional magnetic resonance imaging technique can be used to determine the range and mode of brain activation. After stroke, EA has been shown to alter brain connectivity, whereas EA's effect on brain network topology properties remains unclear. An evaluation of EA's effects on global and nodal topological properties in rats with ischemia reperfusion was conducted in this study. There were three groups of adult male Sprague-Dawley rats: sham-operated group (sham group), middle cerebral artery occlusion/reperfusion (MCAO/R) group, and MCAO/R plus EA (MCAO/R+EA) group. The differences in global and nodal topological properties, including shortest path length, global efficiency, local efficiency, small-worldness index, betweenness centrality (BC), and degree centrality (DC) were estimated. Graphical network analyses revealed that, as compared with the sham group, the MCAO/R group demonstrated a decrease in BC value in the right ventral hippocampus and increased BC in the right substantia nigra, accompanied by increased DC in the left nucleus accumbens shell (AcbSh). The BC was increased in the right hippocampus ventral and decreased in the right substantia nigra after EA intervention, and MCAO/R+EA resulted in a decreased DC in left AcbSh compared to MCAO/R. The results of this study provide a potential basis for EA to promote cognitive and motor function recovery after ischemic stroke.

Nematicidal activity and action mode of a methyl-accepting chemotaxis protein from Pseudomonas syringae against Caenorhabditis elegans

The conventional phytopathogen Pseudomonas syringae reportedly possesses several virulence determinants against Caenorhabditis elegans; however, their action mechanisms remain elusive. This study reports the nematicidal activity and action receptor of a methyl-accepting chemotaxis protein (MCP03) of a wild-type P. syringae MB03 against C. elegans. Purified MCP03 exhibited nematicidal toxicity against C. elegans at a half-lethal concentration of 124.4 μg mL−1, alongside detrimental effects on the growth and brood size of C. elegans. Additionally, MCP03-treated worms exhibited severe pathological destruction of the intestine and depressed wrinkles of the cuticle. Yeast two-hybrid assays identified a subunit of COP9 signalosome, namely CSN-5, which functioned as an MCP03 action receptor. In vitro pull-down verified the binding interaction between MCP03 and CSN-5. RNA interference assays confirmed that MCP03 antagonizes CSN-5, thereby adversely affecting the brood size and cuticle integrity of C. elegans. Following MCP03 infection, the expression of genes related to reproduction, growth, and cuticle formation, such as kgb-1, unc-98, and col-117, was considerably downregulated, indicating pathological changes in MCP03-treated nematodes. Therefore, we proposed that MCP03 antagonizes CSN-5, causing lethality as well as detrimental effects on the fertility, growth, and morphogenesis of C. elegans, which can provide new insights into the signaling pathways and mechanisms underlying the nematicidal action of MCP03 toward C. elegans.

Anisotropic quasi-static permittivity of rare-earth scandate single crystals measured by terahertz spectroscopy

We report the real-valued static and complex-valued quasi-static anisotropic permittivity parameters of rare-earth scandate orthorhombic single crystal GdScO3 (GSO), TbScO3 (TSO), and DyScO3 (DSO). Employing continuous-wave terahertz spectroscopy (0.2–1 THz), the complex permittivity was extracted using an anisotropic ambient-film-ambient model. Data obtained from multiple samples of the same oxides and different surface cuts were analyzed simultaneously. The zero-frequency limit of the modeled data indicates that at room temperature the real part of the dielectric tensor components for GSO are ɛa = 22.7, ɛb = 19.3, and ɛc = 28.1; for DSO, ɛa = 20.3, ɛb = 17.4, and ɛc = 31.1; and for TSO, ɛa = 21.6, ɛb = 18.1, and ɛc = 30.3, with a, b, and c crystallographic axes constituting the principal directions for the permittivity tensor. These results are in excellent agreement with expectations from theoretical computations and with scarcely available data from previous experimental studies. Furthermore, our results evidence a noticeable attenuation, which increases with frequency, and are very significant especially at the higher frequency end of the measurement and along the c-direction in all samples. We suggest the attenuation is most likely caused by the onset of absorption due to long-wavelength active optical phonon modes. These results are important for electronic and potential sub-terahertz applications (e.g., quarter-wave plate) benefiting from the large index contrast along different directions in these materials.

Frequency-influenced dielectric analysis of sol-gel assisted Mg2+ substituted ZnMn2O4 nanoparticles

This study deals with the effect of Mg2+ doping on the structural, optical, and dielectric properties of zinc manganite nanoparticles. A series of MgxZn1-xMn2O4 (x = 0–0.5) samples were prepared with an auto-combustion synthesis method. Rietveld refinement of XRD revealed a pure tetragonal inverse spinel phase, supported by FTIR spectral analysis. Morphological studies indicated the transformation of micro-spherical to rod-like shapes for doped samples. With increased dopant concentration, the three Raman active modes shift towards higher frequencies. The co-existence of Mn2+, Mn3+, and Mn4+ states was revealed by chemical state analysis. The MZMO-5 sample exhibited the smallest energy bandgap (∼1.64 eV). The refractive indices of these samples were estimated to be ∼ 0.4 which might be useful for switching and filter circuits. These nano-manganite samples exhibited high dielectric constants and low losses, indicating their potential use in communication devices.

An integrated geospatial data model for active travel infrastructure

Active travel has received increased investment and interest in many countries both due to COVID-19 and to policies which promote a shift in mobility behaviours to support a wide range of public and individual goods. However, while there has often been substantial investment in the physical infrastructure that can help facilitate active travel, there has not so far always been commensurate investment in the data infrastructure which can help enable people to shift trips to active modes. Current fragmented data and data models and a lack of data standards pose a barrier to the development of the applications which are needed to support planners, users and journey planning. There is therefore a need for a more integrated, better-connected and more richly attributed active travel geospatial network model. This paper describes the development of such a data model, and its initial application to a case study of Great Britain. It demonstrates how the development, population and maintenance of such a data model could facilitate a range of novel applications, such as the personalisation of active travel journey planning to address different user needs and capabilities. If the potential societal benefits from investment in physical active travel infrastructure are to be fully realised, this needs to be supported by the availability of a robust spatial data infrastructure capable of providing the information required by walkers, wheeled users and cyclists to make effective use of the active travel network.

Vibration analysis of active composite structures embedded with long and short shape memory alloy (SMA) fibers

The shape memory effect (SME) is a source of internal compressive stresses that modify the vibration behavior of shape memory alloy (SMA) embedded composite structures. Generally, long fibers are used due to their suitability for activating SMA using resistive heating. Longer SMA fibers embedded in composite structures have their limitations in design and manufacturing. Minimal research work has been done on tuning the vibration behavior of composite structures embedded with short SMA fibers. In this research paper, an analytical model for evaluating the natural frequencies of an SMA embedded composite beam has been proposed. Effects of various design parameters for long (continuous) and short (discontinuous) SMA fibers embedded in composites have been investigated. It was observed that short SMA fibers with a higher aspect ratio can tune their frequencies similarly to long SMA fiber composites and are more effective in thicker beams. Matrix material with negative coefficient thermal expansion is more suitable for embedding SMA for modifying natural frequency in active mode.

Application of Sentinel-1 InSAR to monitor tailings dams and predict geotechnical instability: practical considerations based on case study insights

Tailings storage facilities (TSFs) impound mining waste behind dams to ensure public safety, but failure incidents have prompted calls for more robust monitoring programs. Satellite-based interferometric synthetic aperture radar (InSAR) has grown in popularity due to its ability to remotely detect millimeter-scale displacements in most urban and some natural terrains. However, there remains a limited understanding of whether InSAR can be as accurate or representative as on-the-ground instruments, whether failures can be predicted in advance using InSAR, and what variables govern the quality and reliability of InSAR results. To address these gaps, we analyze open-source, medium-resolution Sentinel-1 data to undertake a ground-truth assessment at a test site and a forensic analysis of five failure cases. We use a commercial software with an automated Persistent Scatterer (PS) workflow (SARScape Analytics) for all case study sites except one and a proprietary algorithm (SqueeSAR) with a dual PS and Distributed Scatterer (DS) algorithm for the ground-truth site and one forensic case. The main goal is to deliver practical insights regarding the influence of algorithm/satellite selection, environmental conditions, site activity, coherence thresholds, satellite-dam geometry, and failure modes. We conclude that Sentinel-1 InSAR can serve as a hazard-screening tool to help guide where to undertake targeted investigations; however, most potential failure modes may not exhibit InSAR-detectable accelerations that could assist with time-of-failure prediction in real time. As such, long-term monitoring programs should ideally be integrated with a combination of remote sensing and field instrumentation to best support engineering practice and judgment.