Although the rapid expansion of urban rail transit offers convenience to citizens, the issue of subway vibration cannot be overlooked. This study investigates the spatial distribution characteristics of vibration in the Fayuan Temple historic and cultural reserve. It involves using a V001 magnetoelectric acceleration sensor capable of monitoring low amplitudes with a sensitivity of 0.298 V/(m/s2), a measuring range of up to 20 m/s2, and a frequency range span from 0.5 to 100 Hz for in situ testing, analyzing the law of vibration propagation in this area, evaluating the impact on buildings, and determining the vibration reduction scheme. The reserve is divided into three zones based on the vertical vibration level measured during the in situ test as follows: severely excessive, generally excessive, and non-excessive vibration. Furthermore, the research develops a dynamic coupling model of vehicle-track-tunnel-stratum-structure to verify the damping effect of the wire spring floating plate track and periodic pile row. It compares the characteristics of three vibration reduction schemes, namely, internal vibration reduction reconstruction, periodic pile row, and anti-vibration reinforcement or reconstruction of buildings, proposing a comprehensive solution. Considering the construction conditions, difficulty, cost, and other factors, a periodic pile row is recommended as the primary treatment measure. If necessary, anti-vibration reinforcement or reconstruction of buildings can serve as supplemental measures.

Assessment of coupling between transtibial sockets and users is historically based on clinicians\' observations and experience, but can be inaccurate and unreliable. Therefore, we present a proof of concept, for five out of six possible degrees of freedom coupling metric system for a socket, using motion analysis calibrated on a 3D printed limb substitute. The method is compatible with any socket suspension method and does not require prior modifications to the socket. Calibration trials were used to locate the axis of rotation of the knee joint referenced against a marker cluster on the thigh; this allowed for the identification of the limb during test trials despite the entire residuum being obscured from view by the socket. The error in the technique was found to be within 0.7 mm in displacement and 0.7 degrees in rotation, based on the control data. Dynamic testing showed the Inter Quartile Range (IQR) of inter time step variance was <0.5 mm/deg for all metrics. The method can form a basis for objective socket evaluation, improve clinical practice and the quality of life for amputees.

Synthetic magnetism has been recently realized using spatiotemporal modulation patterns, producing non-reciprocal steering of charge-neutral particles such as photons and phonons. Here, we design and experimentally demonstrate a non-reciprocal acoustic system composed of three compact cavities interlinked with both dynamic and static couplings, in which phase-correlated modulations induce a synthetic magnetic flux that breaks time-reversal symmetry. Within the rotating wave approximation, the transport properties of the system are controlled to efficiently realize large non-reciprocal acoustic transport. By optimizing the coupling strengths and modulation phases, we achieve frequency-preserved unidirectional transport with 45-dB isolation ratio and 0.85 forward transmission. Our results open to the realization of acoustic non-reciprocal technologies with high efficiency and large isolation, and offer a route towards Floquet topological insulators for sound.

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During upright standing, individuals often use co-contraction muscle activity at the ankle joint when encountering increased postural difficulty; however, this strategy has been shown to be maladaptive. The purpose of the current investigation was to examine the effect of sloped standing on postural sway and muscle co-contraction at the ankle joint as a function of postural difficulty. Twelve young (21.67 ± 1.11 years) adults performed upright standing on flat, declined, and inclined support surfaces. Center of pressure displacements indexed postural sway while electromyography data were collected for the tibialis anterior and gastrocnemius medialis muscles. A co-contraction index and a nonlinear coupling metric (cross-approximate entropy) were computed between ankle dorsiflexor and plantar flexor muscles (tibialis anterior/gastrocnemius medialis) activity. The results showed that higher degrees of postural difficulty led to increased amounts of sway as well as increased sway regularity. Lower co-contraction index was observed for higher degrees of postural difficulty; however, increased dynamic coupling occurred with deviations from the flat standing condition. Overall, increased postural difficulty as manipulated by sloped standing (in either inclined or declined conditions) resulted in individuals adopting a more regular sway trajectory that may be due, in part, to a stronger dynamic coupling strategy occurring at the neuromuscular level.

Respiratory modulation of forebrain activity, long considered hard to reliably separate from breathing artefacts, has been firmly established in recent years using a variety of advanced techniques. Respiratory-related oscillation (RRO) is derived from rhythmic nasal airflow in the olfactory bulb (OB) and is conveyed to higher order brain networks, including the prefrontal cortex (PFC) and hippocampus (HC), where it may potentially contribute to communication between these structures by synchronizing their activities at the respiratory rate. RRO was shown to change with sleep-wake states; it is strongest in quiet waking, somewhat less in active waking, characterized with theta activity in the HC, and absent in sleep. The goal of this study was to test RRO synchronization between PFC and HC under urethane anaesthesia where theta and non-theta states spontaneously alternate. We found that in theta states, PFC-HC coherences significantly correlated with OB-HC but not with OB-PFC, even though RRO was stronger in PFC than in HC. In non-theta states, PFC-HC synchrony correlated with coherences connecting OB to either PFC or HC. Thus, similar to freely behaving rats, PFC-HC synchrony at RRO was primarily dependent on the response of HC to the common rhythmic drive, but only in theta state. The findings help outlining the value and the limits of applications in which urethane-anaesthetized rats can be used for modelling the neural mechanisms of RRO in behaving animals.

Solid materials have been used extensively for various kinds of structural components in our surroundings. Stability of such solid structures, including not only machinery, architectural and civil structures but also our solid earth, is largely governed by fracture development in the solids. Especially, dynamic fracture, once occurring-quite often unexpectedly-evolves very rapidly and can lead to catastrophic structural failures and disasters like earthquakes. However, contrary to slowly enlarging fractures that can be recognized spatio-temporally in detail, it is extremely difficult to trace dynamically growing fractures even in controlled laboratory experimental conditions, and its physics still remains unexplored. This theme issue introduces and summarizes recent advancements in our understanding of the widespread topics of dynamic fracture of solids from well-assorted perspectives, involving laboratory experiments, simulations and analytical methods as well as field observations, with the common background of mechanics of fracture. Multi-scale subjects range from fracture of metals at atom or particle levels to disastrous rock bursts in deep gold mines and detection of unique signals before devastating fracture such as large, global-scale earthquakes. This article is part of the theme issue \'Fracture dynamics of solid materials: from particles to the globe\'.

Anterior cruciate ligament (ACL) injuries commonly occur during single-leg landing tasks and are a burdensome condition. Previous studies indicate that muscle forces play an important role in controlling ligamentous loading, yet these studies have typically used cadaveric models considering only the knee-spanning quadriceps, hamstrings, and gastrocnemius muscle groups. Any muscles (including non-knee-spanning muscles) capable of opposing the anterior shear joint reaction force and the valgus joint reaction moment are thought to have the greatest potential for protecting the ACL from injury. Thus, the purpose of this study was to investigate how lower-limb muscles modulate knee joint loading during a single-leg drop landing task. An electromyography-informed neuromusculoskeletal modeling approach was used to compute lower-limb muscle force contributions to the anterior shear joint reaction force and the valgus joint reaction moment at the knee during a single-leg drop landing task. The average shear joint reaction force ranged from 153 N of anterior shear force to 744 N of posterior shear force. The muscles that generated the greatest posterior shear force were the soleus, medial hamstrings, and biceps femoris, contributing up to 393 N, 359 N, and 162 N, respectively. The average frontal plane joint reaction moment ranged from a 19 Nm varus moment to a 6 Nm valgus moment. The valgus moment was primarily opposed by the gluteus medius, gluteus minimus, and soleus, with these muscles providing contributions of up to 38, 22, and 20 Nm toward a varus moment, respectively. The findings identify key muscles that mitigate loads on the ACL.

The tibiofemoral compressive forces experienced during functional activities are believed to be important for maintaining tibiofemoral stability. Previous studies have shown that both knee-spanning and non-knee-spanning muscles contribute to tibiofemoral joint compressive forces during walking. However, healthy individuals typically engage in more vigorous activities (e.g. jumping and cutting) that provide greater challenges to tibiofemoral stability. Despite this, no previous studies have investigated how both knee-spanning and non-knee-spanning muscles contribute to tibiofemoral compressive loading during such tasks. The present study investigated how muscles contributed to the medial and lateral compartment tibiofemoral compressive forces during sidestep cutting. Three-dimensional marker trajectories, ground reaction forces and muscle electromyographic signals were collected from eight healthy males whilst they completed unanticipated sidestep cutting. OpenSim was used to perform musculoskeletal simulations to compute the contribution of each lower-limb muscle to compressive loading of each compartment of the knee. The greatest contributors to medial compartment loading were the vasti, gluteus maximus and medius, and the medial gastrocnemius. The greatest contributors to lateral compartment loading were the vasti, adductors, medial and lateral gastrocnemius, and the soleus. The soleus displayed the greatest potential for unloading the medial compartment, whereas the gluteus maximus and medius displayed the greatest potential for unloading the lateral compartment. These findings may help to inform interventions aiming to modulate compressive loading at the knee.

Many aldehydes, such as furfural, are present in high quantities in lignocellulose lysates and are fermentation inhibitors, which makes biofuel production from this abundant carbon source extremely challenging. Cbei_3974 has recently been identified as an aldo-keto reductase responsible for partial furfural resistance in Clostridium beijerinckii Rational engineering of this enzyme could enhance the furfural tolerance of this organism, thereby improving biofuel yields. We report an extensive characterization of Cbei_3974 and a single-crystal X-ray structure of Cbei_3974 in complex with NADPH at a resolution of 1.75 Å. Docking studies identified residues involved in substrate binding, and an activity screen revealed the substrate tolerance of the enzyme. Hydride transfer, which is partially rate limiting under physiological conditions, occurs from the pro-R hydrogen of NADPH. Enzyme isotope labeling revealed a temperature-independent enzyme isotope effect of unity, indicating that the enzyme does not use dynamic coupling for catalysis and suggesting that the active site of the enzyme is optimally configured for catalysis with the substrate tested.IMPORTANCE Here we report the crystal structure and biophysical properties of an aldehyde reductase that can detoxify furfural, a common inhibitor of biofuel fermentation found in lignocellulose lysates. The data contained here will serve as a guide for protein engineers to develop improved enzyme variants that would impart furfural resistance to the microorganisms used in biofuel production and thus lead to enhanced biofuel yields from this sustainable resource.