321 research outputs found

    DS-K3DOM: 3-D Dynamic Occupancy Mapping with Kernel Inference and Dempster-Shafer Evidential Theory

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    Occupancy mapping has been widely utilized to represent the surroundings for autonomous robots to perform tasks such as navigation and manipulation. While occupancy mapping in 2-D environments has been well-studied, there have been few approaches suitable for 3-D dynamic occupancy mapping which is essential for aerial robots. This paper presents a novel 3-D dynamic occupancy mapping algorithm called DSK3DOM. We first establish a Bayesian method to sequentially update occupancy maps for a stream of measurements based on the random finite set theory. Then, we approximate it with particles in the Dempster-Shafer domain to enable real time computation. Moreover, the algorithm applies kernel based inference with Dirichlet basic belief assignment to enable dense mapping from sparse measurements. The efficacy of the proposed algorithm is demonstrated through simulations and real experiments.Comment: 7 pages, 2 figures, submitted to ICRA 202

    TIBIO-FEMORAL JOINT FORCES DURING THE LANDING PHASE OF DIFFERENT TYPES OF VERTICAL JUMP

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    The purpose of this study was to compare the tibio-femoral contact forces during the landing phases of 8 different types of vertical jump (squat, countermovement, hop approach and drop jumps each with and without the use of arms). Data were collected from eight males and eight females. Two S-VHS camcorders and a force platform were used to obtain the 3-D kinematics and kinetics of the knee joint. Activities of selected muscles spanning the knee joint were monitored using surface electromyographic (EMG) techniques. The EMG-assisted optimization model was used to estimate the tibio-femoral joint forces. The peak compressive contact forces ranged from 3-5 body weight (SW) and from 2.5-3.7 SW for the males and females, respectively. These loads seldom fell within the range that is considered to be damaging to the cartilage at the knee

    Cost-effective circadian mechanism: rhythmic degradation of circadian proteins spontaneously emerges without rhythmic post-translational regulation

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    Circadian protein oscillations are maintained by the lifelong repetition of protein production and degradation in daily balance. It comes at the cost of ever-replayed, futile protein synthesis each day. This biosynthetic cost with a given oscillatory protein profile is relievable by a rhythmic, not constant, degradation rate that selectively peaks at the right time of day but remains low elsewhere, saving much of the gross protein loss and of the replenishing protein synthesis. Here, our mathematical modeling reveals that the rhythmic degradation rate of proteins with circadian production spontaneously emerges under steady and limited activity of proteolytic mediators and does not necessarily require rhythmic post-translational regulation of previous focus. Additional (yet steady) post-translational modifications in a proteolytic pathway can further facilitate the degradation's rhythmicity in favor of the biosynthetic cost saving. Our work is supported by animal and plant circadian data, offering a generic mechanism for potentially widespread, time-dependent protein turnover

    Fabrication and magnetic properties of Fe nanostructures in anodic alumina membrane

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    Several Fe nanostructures with different lengths, diameters, and separations of the constituting magnetic components have been synthesized using anodized alumina membranes (AAMs) to understand the influence of these parameters on their magnetic properties. Fe nanostructures with high crystallinity and (110) orientation were synthesized by electrodeposition at room temperature in regular AAMs and mild-hard AAM (Mi-Ha AAM). Fe nanostructures with different aspect ratios (1:1, 1:10, and 1:75) in the form of nanodots, nanorods, or nanowires were synthesized in regular AAMs with the 100 nm interpore distance. Mi-Ha AAMs with two different pore sizes (70 and 120 nm) and 250 nm interpore distances were used to investigate the effect of the interactions and of the diameter of the wires on their magnetic behavior. Nearly linear magnetization characteristics with small coercivity, observed for Fe nanowires, suggest the magnetization rotation to be the predominant magnetization process for the field applied transverse to the wires. The anisotropy of the arrays was governed by the shape anisotropy of the magnetic objects with different aspect ratios. Reduced interactions between the nanowires grown in Mi-Ha AAMs resulted in enhancement of the average anisotropy. It is believed that due to difference in spin configuration, the increased diameter of the nanowires led to reduction in the coercivity in the case of the field applied along the wires

    THE EFFECTS OF WEARING SPANDEX GARMENT WITH COMPRESSION BAND ON KINEMATIC VARIABLES DURING A GOLF SWING

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    The purpose of this study was to investigate how spandex garment with compressive band affects kinematic variables during a golf swing. The X-factor and angular velocity of the club in EG were increased during the down swing phase, whereas the significant changes of other kinematic variables were not found in this study. Thus, the effects of wearing spandex garment with compression band cannot be explained as a function of the kinematic variables of interest. It is clear that wearing spandex garment with compressive band may enhance joint stability, which in turn may affect joint kinetics and muscle activation. This has led to suggestions of the need for further kinetic and EMG analyses to evaluate its function

    Negative regulation of floral transition in Arabidopsis by HOS15-PWR-HDA9 complex

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    Arabidopsis HOS15/PWR/HDA9 repressor complex, which is similar to the TBL1/NcoR1/HDAC complex in animals, plays a well-known role in epigenetic regulation. PWR and HDA9 have been reported to interact with each other and modulate the flowering time by repressing AGL19 expression, whereas HOS15 and HDA9, together with the photoperiodic evening complex, regulate flowering time through repression of GI transcription. However, the role of the HOS15/PWR/HDA9 core repressor complex as a functional unit in the regulation of flowering time is yet to be explored. In this study, we reported that the loss-of-function hos15-2/pwr/hda9 triple mutant accumulates higher transcript levels of AGL19 and exhibits an early flowering phenotype similar to those of hos15, pwr, and hda9 single mutants. Interestingly, the accumulation of HOS15 in the nucleus was drastically reduced in pwr and hda9 mutants. As a result, HOS15 could not perform its role in histone deacetylation or interaction with H3 in the nucleus. Furthermore, HOS15 is also associated with the same region of the AGL19 promoter known for PWR-HDA9 binding. The acetylation level of the AGL19 promoter was increased in the hos15-2 mutant, similar to the pwr and hda9 mutants. Therefore, our findings reveal that the HOS15/PWR/HDA9 repressor complex deacetylates the promoter region of AGL19, thereby negatively regulating AGL19 transcription, which leads to early flowering in Arabidopsis
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