1,055 research outputs found
EFFECTS OF SHOD AND BAREFOOT RUNNING ON THE IN VIVO KINEMATICS OF THE FIRST METATARSOPHALANGEAL JOINT
The purpose of this study is to investigate the differences of the first metatarsophalangeal joint’s 6 degree-of-freedom (6DOF) kinematics during shod and barefoot conditions by using a high-speed dual fluoroscopic imaging system (DFIS). Fifteen healthy male runners were recruited. Computed tomography (CT) scans were taken of each participant’s right foot for the construction of 3D models and local coordinate system. The fluoroscopic images of the right foot during the stance period were acquired under shod and barefoot condition with rearfoot strike pattern Radiographic images were acquired at 100 Hz while the participants ran at a speed of 3±5% m/s in a track and 6DOF kinematics were calculated by 2D-3D registration. Paired sample t-test was used to compare the kinematic characteristics of the first MTPJ 6DOF kinematics between shod and barefoot. Compared with barefoot, wearing shoes 1) decreased the peak medial, posterior, and superior translation of the first MTPJ during stance (P < 0.05); 2) decreased maximum extension angle, minimum extension angle, and flexion/extension range of motion of the first MTPJ during stance (P < 0.05); 3) increased minimum adduction angle of the first MTPJ during stance (P < 0.05). It suggests that shoes may affect the function of the first MTPJ and increase the risk of hallux valgus. Our study makes up for the deficiency of traditional motion measurement methods that only focus on the sagittal flexion and extension movement of the first MTPJ and provides a more comprehensive understanding of the potential relationship between joint motion and injurie
MSAT: Matrix stability analysis tool for shock-capturing schemes
The simulation of supersonic or hypersonic flows often suffers from numerical
shock instabilities if the flow field contains strong shocks, limiting the
further application of shock-capturing schemes. In this paper, we develop the
unified matrix stability analysis method for schemes with three-point stencils
and present MSAT, an open-source tool to quantitatively analyze the shock
instability problem. Based on the finite-volume approach on the structured
grid, MSAT can be employed to investigate the mechanism of the shock
instability problem, evaluate the robustness of numerical schemes, and then
help to develop robust schemes. Also, MSAT has the ability to analyze the
practical simulation of supersonic or hypersonic flows, evaluate whether it
will suffer from shock instabilities, and then assist in selecting appropriate
numerical schemes accordingly. As a result, MSAT is a helpful tool that can
investigate the shock instability problem and help to cure it.Comment: 18 pages, 6 figure
EFFECTS OF SHOD AND BAREFOOT CONDITIONS ON MEDIAL LONGITUDINAL ARCH ANGLE DURING RUNNING
The structure of the medial longitudinal arch (MLA) affects the spring-like function of the foot and is crucial to running performance. The purpose of this study was to investigate the differences in the MLA angle between barefoot and shod conditions by using a high-speed dual fluoroscopic imaging system (DFIS). Computed tomography was taken of each participant’s right foot for the construction of 3D models and local coordinate systems. Fifteen participants ran with or without running shoes at 3 m/s±5% speed. We recorded foot kinematics using DFIS. After the process of 3D-2D registration, MLA angles were calculated. Compared to barefoot, wearing shoes 1) decreased the initial landing MLA angle, maximum MLA angle and range of motion of the MLA angle (p \u3c 0.05); 2) decreased the MLA angles during 0%-70% of the stance phase (p \u3c 0.05). It suggests that shoes limit the MLA compression and recoil and its spring-like function
Effects of different habitual foot strike patterns on in vivo kinematics of the first metatarsophalangeal joint during shod running—a statistical parametric mapping study
Existing studies on the biomechanical characteristics of the first metatarsophalangeal joint (1st MTPJ) during shod running are limited to sagittal plane assessment and rely on skin marker motion capture, which can be affected by shoes wrapping around the 1st MTPJ and may lead to inaccurate results. This study aims to investigate the in vivo effects of different habitual foot strike patterns (FSP) on the six degrees of freedom (6DOF) values of the 1st MTPJ under shod condition by utilizing a dual-fluoroscopic imaging system (DFIS). Long-distance male runners with habitual forefoot strike (FFS group, n = 15) and rearfoot strike (RFS group, n = 15) patterns were recruited. All participants underwent foot computed tomography (CT) scan to generate 3D models of their foot. The 6DOF kinematics of the 1st MTPJ were collected using a DFIS at 100 Hz when participants performed their habitual FSP under shod conditions. Independent t-tests and one-dimensional statistical parametric mapping (1-d SPM) were employed to analyze the differences between the FFS and RFS groups’ 1st MTPJ 6DOF kinematic values during the stance phase. FFS exhibited greater superior translation (3.5–4.9 mm, p = 0.07) during 51%–82% of the stance and higher extension angle (8.4°–10.1°, p = 0.031) during 65%–75% of the stance in the 1st MTPJ than RFS. Meanwhile, FFS exhibited greater maximum superior translation (+3.2 mm, p = 0.022), maximum valgus angle (+6.1°, p = 0.048) and varus–valgus range of motion (ROM) (+6.5°, p = 0.005) in the 1st MTPJ during stance. The greater extension angle of the 1st MTPJ in the late stance suggested that running with FFS may enhance the propulsive effect. However, the higher maximum valgus angle and the ROM of varus–valgus in FFS may potentially lead to the development of hallux valgus
Learning to Navigate in a VUCA Environment: Hierarchical Multi-expert Approach
Despite decades of efforts, robot navigation in a real scenario with
volatility, uncertainty, complexity, and ambiguity (VUCA for short), remains a
challenging topic. Inspired by the central nervous system (CNS), we propose a
hierarchical multi-expert learning framework for autonomous navigation in a
VUCA environment. With a heuristic exploration mechanism considering target
location, path cost, and safety level, the upper layer performs simultaneous
map exploration and route-planning to avoid trapping in a blind alley, similar
to the cerebrum in the CNS. Using a local adaptive model fusing multiple
discrepant strategies, the lower layer pursuits a balance between
collision-avoidance and go-straight strategies, acting as the cerebellum in the
CNS. We conduct simulation and real-world experiments on multiple platforms,
including legged and wheeled robots. Experimental results demonstrate our
algorithm outperforms the existing methods in terms of task achievement, time
efficiency, and security.Comment: 8 pages, 10 figure
BMPRIA mediated signaling is essential for temporomandibular joint development in mice
The central importance of BMP signaling in the development and homeostasis of synovial joint of appendicular skeleton has been well documented, but its role in the development of temporomandibular joint (TMJ), also classified as a synovial joint, remains completely unknown. In this study, we investigated the function of BMPRIA mediated signaling in TMJ development in mice by transgenic loss-of- and gain-of-function approaches. We found that BMPRIA is expressed in the cranial neural crest (CNC)-derived developing condyle and glenoid fossa, major components of TMJ, as well as the interzone mesenchymal cells. Wnt1-Cre mediated tissue specific inactivation of BmprIa in CNC lineage led to defective TMJ development, including failure of articular disc separation from a hypoplastic condyle, persistence of interzone cells, and failed formation of a functional fibrocartilage layer on the articular surface of the glenoid fossa and condyle, which could be at least partially attributed to the down-regulation of Ihh in the developing condyle and inhibition of apoptosis in the interzone. On the other hand, augmented BMPRIA signaling by Wnt1-Cre driven expression of a constitutively active form of BmprIa (caBmprIa) inhibited osteogenesis of the glenoid fossa and converted the condylar primordium from secondary cartilage to primary cartilage associated with ectopic activation of Smad-dependent pathway but inhibition of JNK pathway, leading to TMJ agenesis. Our results present unambiguous evidence for an essential role of finely tuned BMPRIA mediated signaling in TMJ development
Recommending Themes for Ad Creative Design via Visual-Linguistic Representations
There is a perennial need in the online advertising industry to refresh ad
creatives, i.e., images and text used for enticing online users towards a
brand. Such refreshes are required to reduce the likelihood of ad fatigue among
online users, and to incorporate insights from other successful campaigns in
related product categories. Given a brand, to come up with themes for a new ad
is a painstaking and time consuming process for creative strategists.
Strategists typically draw inspiration from the images and text used for past
ad campaigns, as well as world knowledge on the brands. To automatically infer
ad themes via such multimodal sources of information in past ad campaigns, we
propose a theme (keyphrase) recommender system for ad creative strategists. The
theme recommender is based on aggregating results from a visual question
answering (VQA) task, which ingests the following: (i) ad images, (ii) text
associated with the ads as well as Wikipedia pages on the brands in the ads,
and (iii) questions around the ad. We leverage transformer based cross-modality
encoders to train visual-linguistic representations for our VQA task. We study
two formulations for the VQA task along the lines of classification and
ranking; via experiments on a public dataset, we show that cross-modal
representations lead to significantly better classification accuracy and
ranking precision-recall metrics. Cross-modal representations show better
performance compared to separate image and text representations. In addition,
the use of multimodal information shows a significant lift over using only
textual or visual information.Comment: 7 pages, 8 figures, 2 tables, accepted by The Web Conference 202
A Universal Theory of Spin Squeezing
We provide extensive numerical and analytic evidence for the following
conjecture: Any Hamiltonian exhibiting finite temperature, easy-plane
ferromagnetism (XY order) can be used to generate scalable spin squeezing, and
thus to perform quantum-enhanced sensing. Our conjecture is guided by a deep
connection between the quantum Fisher information of pure states and the
spontaneous breaking of a continuous symmetry. We demonstrate that
spin-squeezing exhibits a phase diagram with a sharp transition between
scalable squeezing and non-squeezing. This transition coincides with the
equilibrium phase boundary for XY order at a finite temperature. In the
scalable squeezing phase, we predict a sensitivity scaling as ,
between the standard quantum limit, , and that achieved in all-to-all
coupled easy-plane spin models, . Our results provide fundamental
insight into the landscape of Hamiltonians that can be used to generate
metrologically useful quantum states.Comment: 6 pages, 3 figures + 12 pages, 6 figure
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