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Steep wave breaking on a vertical cylinder (a typical foundation supporting offshore wind turbines) will induce slam loads. Many questions on the important violent wave loading and the associated secondary load cycle remain unanswered. We use laboratory experiments with unidirectional waves to investigate the fluid loading on vertical cylinders. We use a novel three-phase decomposition approach that allows us to separate different types of nonlinearity. Our findings reveal the existence of an additional quasi-impulsive loading component that is associated with the secondary load cycle and occurs in the backwards direction against that of the incoming waves. This quasi-impulsive force occurs at the end of the secondary load cycle and close to the passage of the downward zero-crossing point of the undisturbed wave. Wavelet analysis showed that the impulsive force exhibits superficially similar behaviour to a typical wave-slamming event but in the reverse direction. To monitor the scattered wave field and extract run-up on the cylinder, we installed a four-camera synchronised video system and found a strong temporal correlation between the arrival time of the Type-II scattered wave onto the cylinder and the occurrence of this quasi-impulsive force. The temporal characteristics of this quasi-impulsive force can be approximated by the Goda wave impact model, taking the collision of the Type-II scattered waves at the rear stagnation point as the impact source.
During the Second World War, a number of manuscript fragments in Iranian languages from the Berlin Turfan collections were lost. Photographs of these fragments preserved in the Nachlass of Walter B. Henning bring to light their contents and fill gaps in the record of Turfan texts. These photographs are published here for the first time, together with a description of the fragments and their contents.
The last three decades have seen significant development in understanding and describing the effects of task complexity on learner internal processes. However, researchers have primarily employed behavioral methods to investigate task-generated cognitive load. Being the first to adopt neuroimaging to study second language (L2) task effects, we aimed to provide novel insights into the neural correlates of task-related variation in L2 oral production. To advance research methodology, we also tested the utility of a neuroimaging technique, functional magnetic resonance imaging (fMRI), in examining the impact of task-related variables on L2 speech production when combined with cognitive–behavioral tools (speech analysis, expert and learner judgments). Our research focus was the effects of task complexity on silent pausing. Twenty-four Japanese learners of English completed eight simple and complex versions of decision-making tasks, half in their first language and half in their L2. The dataset for the present study included the L2 speech and fMRI data, expert judgments, and participants’ difficulty ratings of the L1 and L2 tasks they completed. Based on our findings, we concluded that brain imaging and L1 task difficulty ratings were more sensitive to detecting task complexity effects than L2 self-ratings and pausing measures. These results point to the benefits of triangulating cognitive and neural data to study task-based neurocognitive processes.
Let $(X,\mu ,T,d)$ be a metric measure-preserving dynamical system such that three-fold correlations decay exponentially for Lipschitz continuous observables. Given a sequence $(M_k)$ that converges to $0$ slowly enough, we obtain a strong dynamical Borel–Cantelli result for recurrence, that is, for $\mu $-almost every $x\in X$,
where $\mu (B_k(x)) = M_k$. In particular, we show that this result holds for Axiom A diffeomorphisms and equilibrium states under certain assumptions.
In this work, the synthesis, characterization, and X-ray powder diffraction data for dichloridodioxido-[(4,7-dimethyl)-1,10-phenanthroline]molybdenum(VI) are reported. The crystal structure of this compound was solved from powder diffraction data using the simulated annealing method with a subsequent refinement using the Rietveld method. The dioxo-molybdenum (VI) complex C14H12Cl2MoN2O2 crystallizes in a monoclinic system with space group C2/c (N° 15) with refined unit-cell parameters a = 12.9495 (5) Å, b = 9.7752 (4) Å,c = 12.0069 (6) Å, β = 101.702 (3) °, unit-cell volume V = 1488.27 (11) Å3, and values of Z′ = 0.5 and Z = 4. The molecules are organized into chains diagonally along the a and c axis. Parallel polyhedra are observed along these axes formed by the interactions of Mo, Cl, O, and N atoms present in the coordination sphere. The crystalline packing of this dioxo-molybdenum (VI) complex is dominated by five intermolecular hydrogen bonds, two intramolecular hydrogen bonds, and the four interactions between the centroids (CgI⋯CgJ) of the aromatic rings. An analysis of the Hirshfeld surface revealed that the greatest contributions of the attractive forces are given by H⋯Cl/Cl⋯H, H⋯C/C⋯H, H⋯O/O⋯H, and H⋯H interactions.
In various industrial robotic applications, the effective traversal of a manipulator amidst obstacles and its ability to reach specific task-points are imperative for the execution of predefined tasks. In certain scenarios, the sequence in which the manipulator reaches these task-points significantly impacts the overall cycle time required for task completion. Moreover, some tasks necessitate significant force exertion at the end-effector. Therefore, establishing an optimal sequence for the task-points reached by the end-effector’s tip is crucial for enhancing robot performance, ensuring collision-free motion and maintaining high-force application at the end-effector’s tip.
To maximize the manipulator’s manipulability, which serves as a performance index for assessing its force capability, we aim to establish an optimal collision-free task sequence considering higher mechanical advantage. Three optimization criteria are considered: the cycle time, collision avoidance and the manipulability index. Optimization is accomplished using a genetic algorithm coupled with the Bump-Surface concept for collision avoidance. The effectiveness of this approach is confirmed through simulation experiments conducted in 2D and 3D environments with obstacles employing both redundant and non-redundant robots.
Thanks to its real-time computation efficiency, deep reinforcement learning (DRL) has been widely applied in motion planning for mobile robots. In DRL-based methods, a DRL model computes an action for a robot based on the states of its surrounding obstacles, including other robots that may communicate with it. These methods always assume that the environment is attack-free and the obtained obstacles’ states are reliable. However, in the real world, a robot may suffer from obstacle localization attacks (OLAs), such as sensor attacks, communication attacks, and remote-control attacks, which cause the robot to retrieve inaccurate positions of the surrounding obstacles. In this paper, we propose a robust motion planning method ObsGAN-DRL, integrating a generative adversarial network (GAN) into DRL models to mitigate OLAs in the environment. First, ObsGAN-DRL learns a generator based on the GAN model to compute the approximation of obstacles’ accurate positions in benign and attack scenarios. Therefore, no detectors are required for ObsGAN-DRL. Second, by using the approximation positions of the surrounding obstacles, ObsGAN-DRL can leverage the state-of-the-art DRL methods to compute collision-free motion commands (e.g., velocity) efficiently. Comprehensive experiments show that ObsGAN-DRL can mitigate OLAs effectively and guarantee safety. We also demonstrate the generalization of ObsGAN-DRL.
The yield stress and shear thinning properties of mucus are identified as critical for ciliary coordination and mucus transport in human airways. We use here numerical simulations to explore the hydrodynamic coupling of cilia and mucus with these two properties using the Herschel–Bulkley model, in a lattice Boltzmann solver for the fluid flow. Three mucus flow regimes, i.e. a poorly organized regime, a swirly regime, and a fully unidirectional regime, are observed and analysed by parametric studies. We systematically investigate the effects of ciliary density, interaction length, Bingham number and flow index on the mucus flow regime formation. The underlying mechanism of the regime formation is analysed in detail by examining the variation of two physical quantities (polarization and integral length) and the evolution of the flow velocity, viscosity and shear-rate fields. Mucus viscosity is found to be the dominant parameter influencing the regime formation when enhancing the yield stress and shear thinning properties. The present model is able to reproduce the solid body rotation observed in experiments (Loiseau et al., Nat. Phys., vol. 16, 2020, pp. 1158–1164). A more precise prediction can be achieved by incorporating non-Newtonian properties into the modelling of mucus as proposed by Gsell et al. (Sci. Rep., vol. 10, 2020, 8405).
Although Greek was the dominant epigraphic language in Cyrenaica throughout the Classical period, Latin was introduced by Roman merchants and administrators at the time of the formation of the province of Crete and Cyrene c. 67 BC, and remained in use, albeit by a constant minority, until at least the fourth century AD, with the last well-dated Latin inscription dating from the Valentinian dynasty. The aim of this article is to provide an overview of Latin inscriptions in the region, based on the IR Cyrenaica 2020 corpus, which brings together hitherto scattered documents and also includes many texts published for the first time. After a general overview of the corpus in terms of geographical, typological and chronological distribution, we will look at the linguistic landscape of ancient Cyrenaica, focusing on the multilingualism of the region, the literacy of the populations, the borrowings from one language to another (Latinisms), and the influences of the western provinces on the Latin of the region, among other topics. Lastly, a series of Latin funerary inscriptions allow us to examine the multiple identities claimed by the populations, as well as the cultural influences between Greek-, Latin- and Libyan-speaking populations.
Collision with powerlines is a major cause of mortality for many bird species, including bustards and sandgrouse. In this work, we used GPS tracking data to identify the hour of collision of three threatened steppe birds, i.e. Little Bustard Tetrax tetrax, Black-bellied Sandgrouse Pterocles orientalis, and Pin-tailed Sandgrouse Pterocles alchata. Out of a data set of 160 GPS-tracked individuals collected over a 13-year period, we detected eight collision events with powerlines or fences. Of these, we were able to determine the timing of 87.5% of the collision events with a resolution accurate to within two hours. Our results reveal that collisions occurred throughout the year and at different hours of the day, presenting a challenge for implementing effective mitigation strategies. The use of dynamic and reflective or luminescent devices may therefore be appropriate to prevent collision of steppe birds with powerlines during the day and night. Overall, this study adds evidence to the utility of using tracking data to better understand anthropogenic mortality in birds.
Trials involving police as defendants are rare but are significant events that give insight into police violence and its adjudication. This article explores the reasoning practices through which court actors navigate the disjunctive accounts created by competing claims of “what happened” in a police shooting. The data is drawn from trial testimony of officers and “use of force experts” in police deadly force cases in the United States. We focus on use of force experts who use a veneer of science and police logic to assert particular visions of officer “reasonableness.” We suggest that the systems of reasoning that lawyers and witnesses use in these cases create accounts of police violence that conflict with mundane reasoning and challenge credibility. We show that the proliferation of different reasoning practices and the elaboration of a “police logic” serve to insulate officers from criticism and accountability—albeit, not always successfully.
Rhabdias are lung-dwelling parasites of anurans and some reptiles. Currently, 93 species are known to exist worldwide. The identification of Rhabdias species is based mainly on morphological traits of hermaphroditic females that generally have a very conserved morphology. However, different approaches, such as the combination of morphological, molecular, and ecological data, have provided advances in identifying and delimiting rhabdiasid species. Here, we describe a new species of Rhabdias from the south of Brazil, with morphological and molecular data. The new species is distinguished from its congeners by having an elongated body, evident cephalic dilation, larger buccal capsule, and large esophagus. In addition to morphological characteristics, we observed significant genetic divergence among the cytochrome oxidase subunit I (COI) sequence of the new species and the closest available sequence, Rhabdias fuelleborni (10.24%–10.87%). Furthermore, phylogenetic reconstructions based on the COI gene indicated that the new species represents a different lineage, constituting an outgroup of the species complexes Rhabdias cf. stenocephala and Rhabdias fuelleborni with Rhabdias sp. 4. Thus, Rhabdias megacephala is the 24th nominal species of the Neotropical region, the 14th Brazilian, and the fourth species described from south of Brazil.
This cross-sectional study investigates the immediate psychological effects of disaster relief operations on team members following 2 consecutive major earthquakes in Turkey.
Methods
A total of 170 participants, including professional firefighters, search and rescue (SAR) workers, and volunteers, were surveyed approximately 1 month after the conclusion of active SAR operations. The study utilizes the DSM-V criteria and the Posttraumatic Stress Disorder Checklist (PCL-5) to assess symptoms of post-traumatic stress disorder (PTSD) among participants.
Results
The findings reveal a point prevalence of 35.3% for probable PTSD, highlighting the substantial psychological impact on disaster relief teams. Factors such as age, residency in affected areas, and active SAR involvement significantly influenced probable PTSD rates. Interestingly, actively engaged SAR members had lower probable PTSD rates, possibly due to their training. Those who directly witnessed the earthquakes had higher scores, highlighting the impact of firsthand exposure. Additionally, individuals aged 50 and above displayed a higher mean total severity score compared to younger participants.
Conclusions
This research contributes to understanding the mental well-being of disaster relief professionals. The study’s findings underscore the importance of timely mental health support and training for these responders, emphasizing the need for preparedness in disaster relief teams.
The dietary habits of Neanderthals are considered an issue of great interest in the literature and have opened an important number of fruitful debates. Indeed, understanding diets can provide important information regarding issues of palaeoenvironmental reconstructions and subsistence strategies. In this respect, dental remains can play a vital role in the conducted efforts to reconstruct the palaeoecological niches securely and accurately since dental microwear analyses have precisely detected dietary patterns of the populations in the past. In this context, the Iberian Peninsula forms an interesting model for examining Neanderthal populations, their subsistence strategies, and adaptive skills. This study aims the examination of already published data in order to provide a holistic approach regarding the dietary habits of H. neanderthalensis populations in the Iberian Peninsula, along with the importance of the utilization of dental microwear analysis in the archaeological record.
In this experimental study, we explore the dynamics of the thermal boundary layer in liquid metal Rayleigh–Bénard convection, covering the parameter ranges of $0.026 \leq$ Prandtl numbers $(Pr) \leq 0.033$ and Rayleigh numbers ($Ra$) up to $2.9\times 10^9$. Our research focuses on characterising the thermal boundary layer near the top plate of a cylindrical convection cell with an aspect ratio of 0.5, distinguishing between two distinct regions: the shear-dominated region around the centre of the top plate and a location near the side wall where the boundary layer is expected to be affected by the impact or ejection of thermal plumes. The dependencies of the boundary layer thickness on $Ra$ at these positions reveal deviating scaling exponents with the difference diminishing as $Ra$ increases. We find stronger fluctuations in the boundary layer and increasing deviation from the Prandtl–Blasius–Pohlhausen profile with increasing $Ra$, as well as in the measurements outside the centre region. Our data illustrate the complex interplay between flow dynamics and thermal transport in low-$Pr$ convection.