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Wheeled robots have the advantages of simple structure, convenient control, and high motion stability, but their ability to traverse complex terrain is widely criticized. In this paper, a new type of variable-diameter wheel is designed. The diameter of the wheel can be changed by simple operations; Such being the case, the ability of the wheel to cross obstacles can be improved. In this paper, the application size of the wheel, which includes the number of spokes, the diameter change ratio of the wheel and the continuity of the wheel rim, was established to analyze the performance of obstacle crossing before and after the diameter change. The results show that the number of spokes, the diameter change ratio and the continuity of the wheel rim are all bound by the design size of the wheel. In other words, for different types of this variable-diameter wheel, the application size can be quickly obtained through calculation so as to facilitate the selection of other parts. Moreover, the stability of wheel motion is simulated. The reliability of the calculation results is verified. These analyses also provide the basis for wheel performance optimization design.

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder caused by several distinct defects in genes responsible for ciliary beating, leading to defective mucociliary clearance often associated with randomization of left/right body asymmetry. Individuals with PCD caused by defective radial spoke (RS) heads are difficult to diagnose owing to lack of gross ultrastructural defects and absence of situs inversus. Thus far, most mutations identified in human radial spoke genes (RSPH) are loss-of-function mutations, and missense variants have been rarely described. We studied the consequences of different RSPH9, RSPH4A, and RSPH1 mutations on the assembly of the RS complex to improve diagnostics in PCD. We report 21 individuals with PCD (16 families) with biallelic mutations in RSPH9, RSPH4A, and RSPH1, including seven novel mutations comprising missense variants, and performed high-resolution immunofluorescence analysis of human respiratory cilia. Missense variants are frequent genetic defects in PCD with RS defects. Absence of RSPH4A due to mutations in RSPH4A results in deficient axonemal assembly of the RS head components RSPH1 and RSPH9. RSPH1 mutant cilia, lacking RSPH1, fail to assemble RSPH9, whereas RSPH9 mutations result in axonemal absence of RSPH9, but do not affect the assembly of the other head proteins, RSPH1 and RSPH4A. Interestingly, our results were identical in individuals carrying loss-of-function mutations, missense variants, or one amino acid deletion. Immunofluorescence analysis can improve diagnosis of PCD in patients with loss-of-function mutations as well as missense variants. RSPH4A is the core protein of the RS head.

The nonreciprocal elastic behavior of flexible spokes is essential for designing a top-loading condition of nonpneumatic wheels to distribute the vehicle load throughout the upper circumferential region of a wheel to replicate the loading mode of their pneumatic counterparts. However, most ad hoc spoke designs had been conducted without considering the top-loading mechanics. Moreover, minimizing the stress concentration on the spokes is also significant for preventing potential failures; however, modification of the geometry to reduce the local stress on the spokes has not yet been studied. In this work, we investigate the effect of nonreciprocal elastic behaviors of curved spokes on the top-loading distribution of nonpneumatic wheels. We also study the geometric effect of nonuniform curved spokes on reducing the local stress concentration. Curved beam spokes with greater curvature can contribute to a high top-loading ratio of nonpneumatic wheels. The nonuniform thickness of curved spokes with the spoke’s ends and center regions can reduce the local stress level by up to 24%. Our design method with varying curvature and nonuniformity of the curved spokes can provide significant design guidelines for nonpneumatic wheels for determining the top-loading ratio, tuning the vertical stiffness, and minimizing local stress on the spokes.

Radial spokes, RS1, RS2, and RS3, are T-shaped, multiprotein complexes that transmit regulatory signals from the central apparatus to outer doublet complexes, including dynein arms. Radial spokes, especially RS3, differ in their morphology, protein composition, and RS base-docked IDAs. Spokes’ defects alter cilia beating frequency, waveform, and amplitude, leading, in humans, to primary ciliary dyskinesia and male infertility. The role of the particular spokes remains unclear. Ciliate Tetrahymena thermophila has three RSP3 paralogs and two or three paralogs of some other RSPs. Using multiple complementary approaches, we demonstrated that Tetrahymena forms RS1 and RS2 subtypes, each with a core composed of various RSP3 paralogs and one type of RSP3-less RS3. We elucidated proteomes of RS1 and RS2 subtypes, RS3, and identified novel RS proteins, including enzymatic proteins involved in local regulation of ADP/ATP levels, the guanylate nucleotide pathway, and protein phosphorylation, whose presence further diversifies RSs’ properties and likely functions.

PurposeThe use of brand slogans that represent brand concepts on app launch pages can improve user brand impressions. The purpose of this paper is to investigate the impact of using animated or static spokes-characters with brand slogans on app launch pages.Design/methodology/approachUsing the theory of attention selection, the authors conducted two experiments to study the boundary and mediation path of the influence of the motion attributes of spokes-characters (static vs animated) on brand memory based on app launch time (3 s vs 5 s), user engagement with spokes-characters and the level of attention to brand slogans.FindingsStudy 1 explores the effect of the interaction between launch time and the motion attributes of spokes-characters on brand memory. The results show that when the launch time of the app is 3 s, the advertisement memory effect of using a static spokes-character is better than that of using an animated spokes-character; when the launch time of the app is 5 s, the advertisement memory effect of using an animated spokes-character is better than that of using a static spokes-character. Study 2 shows that user engagement with spokes-characters and the level of attention given to brand slogans play a continuous mediating role in the effect of the interaction between launch time and the motion attributes of spokes-characters on brand memory.Originality/valueThis paper contributes to the marketing literature by expanding the knowledge of spokes-characters and animated visual images, providing new insights for future research.

Complex surgical care is often centralized to one high volume (hub) hospital within a system. The benefit of this centralization in common operations is unknown. Using the Healthcare Cost and Utilization Project's State Inpatient Databases, adult general surgical patients within hospital systems in 13 states (2016–2018) were identified. Risk-adjusted logistic regression estimated the odds of death or serious morbidity (DSM) and prolonged length of stay (LOS) at hubs relative to other system hospitals (spokes). We identified 122,895 patients across 43 hub-and-spoke systems. Hubs completed 83.2 ​% of complex and 59.6 ​% of common operations. For complex operations, odds of DSM were significantly lower in hubs (OR: 0.80; 95 ​% CI [0.65, 0.98]). For common operations, odds of DSM were similar between hubs and spokes, while odds of prolonged LOS were greater at hubs (OR 1.19; 95 ​% CI [1.16,1.24]). While hub hospitals had lower odds of DSM for complex operation, they had higher odds of prolonged length of stay for common operations. This finding shows an opportunity for improved system efficiency. •The majority of surgical care within hospital systems, regardless of complexity, occurred at hub hospitals.•For complex operations, the odds of DSM were lower at hub hospitals with no relative difference in length of stay.•For common operations, odds of prolonged LOS were higher at hub hospitals with no relative benefit to the odds of DSM.

Streptomyces are a genus of ubiquitous soil bacteria from which the majority of clinically utilized antibiotics derive1. The production of these antibacterial molecules reflects the relentless competition Streptomyces engage in with other bacteria, including other Streptomyces species1,2. Here we show that in addition to smallmolecule antibiotics, Streptomyces produce and secrete antibacterial protein complexes that feature a large, degenerate repeat-containing polymorphic toxin protein. A cryo-electron microscopy structure of these particles reveals an extended stalk topped by a ringed crown comprising the toxin repeats scaffolding five lectin-tipped spokes, which led us to name them umbrella particles. Streptomyces coelicolor encodes three umbrella particles with distinct toxin and lectin composition. Notably, supernatant containing these toxins specifically and potently inhibits the growth of select Streptomyces species from among a diverse collection of bacteria screened. For one target, Streptomycesgriseus, inhibition relies on a single toxin and that intoxication manifests as rapid cessation of vegetative hyphal growth. Our data showthatSřrepřozTiycesumbrellaparticlesmediate competition among vegetative mycelia of related species, a function distinct from small-molecule antibiotics, which are produced at the onset of reproductive growth and act broadly3,4. Sequence analyses suggest that this role of umbrella particles extends beyond Streptomyces, as we identified umbrella loci in nearly 1,000 species across Actinobacteria.

The flagella of mammalian sperm display non-planar, asymmetric beating, in contrast to the planar, symmetric beating of flagella from sea urchin sperm and unicellular organisms. The molecular basis of this difference is unclear. Here, we perform in situ cryo-electron tomography of mouse and human sperm, providing the highest-resolution structural information to date. Our subtomogram averages reveal mammalian sperm-specific protein complexes within the microtubules, the radial spokes and nexin–dynein regulatory complexes. The locations and structures of these complexes suggest potential roles in enhancing the mechanical strength of mammalian sperm axonemes and regulating dynein-based axonemal bending. Intriguingly, we find that each of the nine outer microtubule doublets is decorated with a distinct combination of sperm-specific complexes. We propose that this asymmetric distribution of proteins differentially regulates the sliding of each microtubule doublet and may underlie the asymmetric beating of mammalian sperm. The flagella of mammalian sperm display non-planar, asymmetric beating, but the molecular basis is unclear. Chen et al. performed in situ cryo-ET of mouse and human sperm and discovered asymmetric distributions of regulatory complexes that could generate asymmetric bending force.

In motile cilia, a mechanoregulatory network is responsible for converting the action of thousands of dynein motors bound to doublet microtubules into a single propulsive waveform. Here, we use two complementary cryo-EM strategies to determine structures of the major mechanoregulators that bind ciliary doublet microtubules in Chlamydomonas reinhardtii . We determine structures of isolated radial spoke RS1 and the microtubule-bound RS1, RS2 and the nexin−dynein regulatory complex (N-DRC). From these structures, we identify and build atomic models for 30 proteins, including 23 radial-spoke subunits. We reveal how mechanoregulatory complexes dock to doublet microtubules with regular 96-nm periodicity and communicate with one another. Additionally, we observe a direct and dynamically coupled association between RS2 and the dynein motor inner dynein arm subform c (IDAc), providing a molecular basis for the control of motor activity by mechanical signals. These structures advance our understanding of the role of mechanoregulation in defining the ciliary waveform. Cryo-EM structures of radial spokes and nexin−dynein regulatory complex (N-DRC) attached to doublet microtubules isolated from Chlamydomonas reinhardtii provide a model for mechanoregulation of motile cilia.