Specific Positional Information Research Articles

Attention-Based Recurrent Autoencoder for Motion Capture Denoising

<p>To resolve the problem of massive loss of MoCap data from optical motion capture, we propose a novel network architecture based on attention mechanism and recurrent network. Its advantage is that the use of encoder-decoder enables automatic human motion manifold learning, capturing the hidden spatial-temporal relationships in motion sequences. In addition, by using the multi-head attention mechanism, it is possible to identify the most relevant corrupted frames with specific position information to recovery the missing markers, which can lead to more accurate motion reconstruction. Simulation experiments demonstrate that the network model we proposed can effectively handle the large-scale missing markers problem with better robustness, smaller errors and more natural recovered motion sequence compared to the reference method.</p> <p> </p>

Position-aware lightweight object detectors with depthwise separable convolutions

Recently, significant improvements have been achieved for object detection algorithm by increasing the size of convolutional neural network (CNN) models, but the resulting increase of computational complexity poses an obstacle to practical applications. And some of the lightweight methods fail to consider the characteristics of object detection into and suffer a huge loss of accuracy. In this paper, we design a multi-scale feature lightweight network structure and specific convolution module for object detection based on depthwise separable convolution, which not only reduces the computational complexity but also improves the accuracy by using the specific position information in object detection. Furthermore, in order to improve the detection accuracy for small objects, we construct a multi-channel position-aware map and propose training based on knowledge distillation for object detection to train the lightweight model effectively. Last, we propose a training strategy based on a key-layer guiding structure to balance performance with training time. The experimental results show that on the COCO dataset that takes the state-of-the-art object detection algorithm, YOLOv3, as the baseline, our model size is compressed to 1/11 while accuracy drops by 7.4 mmAP, and the computational latency on the GPU and ARM platforms are reduced to 43.7% and 0.29%, respectively. Compared with the state-of-the-art lightweight object detection model, MNet V2 + SSDLite, the accuracy of our model increases by 3.5 mmAP while the inferencing time stays nearly the same. On the PASCAL VOC2007 dataset, the accuracy of our model increases by 5.2 mAP compared to the state-of-the-art lightweight algorithm based on knowledge distillation. Therefore, in terms of accuracy, parameter count, and real-time performance, our algorithm has better performance than lightweight algorithms based on knowledge distillation or depthwise separable convolution.

Exploring the effects of position-related information on the perception of scenario-based passing opportunities

When football players are preparing to pass the ball, they consider contextual information provided by the current game situation to identify passing opportunities and choose the one that appears most beneficial. In the search for contextual information indicating such opportunities, a recent study analyzing the relationships between the position-related characteristics of game situations and athletes’ passing behavior reports that athletes generally prioritize passing options based on their team members’ areal proximity, the openness of the passing lanes leading to team members, and how closely the team members are covered by the opponents. While the found relationships indicate the positional features’ relevance to the athletes’ passing behavior, the importance of single bits of positional information and their integration into subjectively perceived passing opportunities remain unknown. The aim of this study is to begin closing this gap and analyze how multiple athletes weigh and integrate position-related information within their subjective process of perceiving passing opportunities.
 The study uses a 3x3x3 within-subject design. Twenty-one football players provided information about the perceived quality of passing opportunities within standardized game scenarios. The data were analyzed using an information integration theoretical approach combined with mixed linear modeling. The results reveal substantial interpersonal differences regarding the importance players attribute to specific positional information and how they integrate the positional information. Two recurring patterns of information integration were found. In most of the cases, the results indicate additive information integration. However, in some cases, the results indicate that players deviate from additive information integration when a single piece of positional information seemingly dominates the athletes’ perceptions. In the future, IIT approaches can be adopted to research designs using virtual reality, including other sets and ranges of contextual information, as well as other sports and sports situations in which the integration of information into subjective perceptions is of interest.

Osteocyte numbers decrease only in postcranial but not in cranial bones in humans of advanced age

BackgroundBone ageing is governed by the linked activities of short-lived osteoblasts and osteoclasts in conjunction with long-lived osteocytes present in osseous structure. Besides their maintenance function, osteogenic cells also gain specific positional information, which may potentially trigger ageing-associated cellular deviations in terminally differentiated osteocytes differently in cranial versus postcranial tissues. MethodsWe therefore investigated bone taken from deceased aged humans explanted at five distinct anatomical positions throughout the body and assessed physical and biological determinants applying radiologic and histologic measures. ResultsWe were able to show that significantly more osteocytes reside in aged cortical bone at cranial positions than within axial or limb skeleton. These cellular states and conditions were not found in the corresponding trabecular bone, where osteocyte numbers remain also high at postcranial positions. Parallel comparative analyses of bone microstructure as analyzed by means of computer tomography showed no significant differences. ConclusionsConsidering differences and commonalities regarding the bone samples, such as loading, mechanisms of ossification or the surrounding stromal cell compartment, our findings indicate that positional information laid down during ontogenetic processes is instructive during the entire life thus potentially also moulding spatial-specific mechanistic distinctions of bone ageing.

Ferrite Position Identification System Operating With Wireless Power Transfer for Intelligent Train Position Detection

Wireless power transfer (WPT) is being developed to supply electric power to electric trains, using a source coil in/on the railway track and a pick-up coil on the train. A number of benefits can be obtained by eliminating the catenary and pantograph currently used for railway electric power supply. However, the WPT employs coils, and the electromagnetic field generated by the WPT can interfere with conventional train detection methods, such as track circuits and RFID, installed on the tracks. Train position information is critical for railway operation, especially for high speed trains. This paper proposes a novel system which provides train position information using a source coil segment. It consists of onboard sensor coils, ferrite blocks designed using specific position information, and a detector. The proposed system can be implemented using the source coil and load coil of the WPT. Information about the train's relative position is obtained by the detection of ferrite blocks distributed within the source coil segment. The train position information provided by the ferrite components is detected by onboard sensor coils and a detector. The proposed ferrite position identification (FPID) system provides accurate train position information and is not affected by WPT electromagnetic interference. The operating principles of the FPID system are presented in detail. The performance of the proposed FPID system was measured by simulations and experiments.

Deployment Algorithms for UAV Airborne Networks Toward On-Demand Coverage

Due to the flying nature of unmanned aerial vehicles (UAVs), it is very attractive to deploy UAVs as aerial base stations and construct airborne networks to provide service for on-ground users at temporary events (such as disaster relief, military operation, and so on). In the constructing of UAV airborne networks, a challenging problem is how to deploy multiple UAVs for on-demand coverage while at the same time maintaining the connectivity among UAVs. To solve this problem, we propose two algorithms: a centralized deployment algorithm and a distributed motion control algorithm. The first algorithm requires the positions of user equipments (UEs) on the ground and provides the optimal deployment result (i.e., the minimal number of UAVs and their respective positions) after a global computation. This algorithm is applicable to the scenario that requires a minimum number of UAVs to provide desirable service for already known on-ground UEs. Differently, the second algorithm requires no global information or computation, instead, it enables each UAV to autonomously control its motion, find the UEs and converge to on-demand coverage. This distributed algorithm is applicable to the scenario where using a given number of UAVs to cover UEs without UEs’ specific position information. In both algorithms, the connectivity of the UAV network is maintained. Extensive simulations validate our proposed algorithms.

RAPTOR: Row and position tracheid organizer in R

Mechanistic understanding of tree-ring formation and its modelling requires a cellular-based and spatially organized characterization of a tree ring, moving from whole rings, to intra-annual growth zones and individual cells. A tracheidogram is a radial profile of conifer anatomical features, such as lumen area and cell wall thickness, of sequentially- and positionally-ranked tracheids. However, its construction is tedious and time-consuming since image-analysis-based measurements do not recognize the position of cells within a radial file, and present-day tracheidograms must be constructed manually.Here we present the R-package RAPTOR that complements tracheid anatomical data obtained from quantitative wood anatomy software (e.g., ROXAS, WinCELL, ImageJ), with the specific positional information necessary for the automated construction of tracheidograms. The package includes functions to read and visualize tracheid anatomical data, and uses local search algorithms to ascribe a ranked position to each tracheid in identified radial files. The package also provides functions to ensure that tracheids are adequately aligned for identifying the first tracheid in each radial file, and obtaining the correct ranking of tracheids along each radial file. Additional functions allow automating the analyses for multiple samples and rings (batch mode) and exporting data and plots for quality control.RAPTOR allows tracheidogram users to take advantage of the latest generation of cell anatomical measuring systems. With this R-package we aim to facilitate the construction of more robust and versatile tracheidograms for the benefit of the research community.

Use of the sun as a heading indicator when caching and recovering in a wild rodent.

A number of diurnal species have been shown to use directional information from the sun to orientate. The use of the sun in this way has been suggested to occur in either a time-dependent (relying on specific positional information) or a time-compensated manner (a compass that adjusts itself over time with the shifts in the sun’s position). However, some interplay may occur between the two where a species could also use the sun in a time-limited way, whereby animals acquire certain information about the change of position, but do not show full compensational abilities. We tested whether Cape ground squirrels (Xerus inauris) use the sun as an orientation marker to provide information for caching and recovery. This species is a social sciurid that inhabits arid, sparsely vegetated habitats in Southern Africa, where the sun is nearly always visible during the diurnal period. Due to the lack of obvious landmarks, we predicted that they might use positional cues from the sun in the sky as a reference point when caching and recovering food items. We provide evidence that Cape ground squirrels use information from the sun’s position while caching and reuse this information in a time-limited way when recovering these caches.

EVD Dualdating Based Online Subspace Learning

Conventional incremental PCA methods usually only discuss the situation of adding samples. In this paper, we consider two different cases: deleting samples and simultaneously adding and deleting samples. To avoid the NP-hard problem of downdating SVD without right singular vectors and specific position information, we choose to use EVD instead of SVD, which is used by most IPCA methods. First, we propose an EVD updating and downdating algorithm, called EVD dualdating, which permits simultaneous arbitrary adding and deleting operation, via transforming the EVD of the covariance matrix into a SVD updating problem plus an EVD of a small autocorrelation matrix. A comprehensive analysis is delivered to express the essence, expansibility, and computation complexity of EVD dualdating. A mathematical theorem proves that if the whole data matrix satisfies the low-rank-plus-shift structure, EVD dualdating is an optimal rank-kestimator under the sequential environment. A selection method based on eigenvalues is presented to determine the optimal rank k of the subspace. Then, we propose three incremental/decremental PCA methods: EVDD-IPCA, EVDD-DPCA, and EVDD-IDPCA, which are adaptive to the varying mean. Finally, plenty of comparative experiments demonstrate that EVDD-based methods outperform conventional incremental/decremental PCA methods in both efficiency and accuracy.

Chromosome architecture is a key element of bacterial cellular organization

The bacterial chromosome encodes information at multiple levels. Beyond direct protein coding, genomes encode regulatory information required to orchestrate the proper timing and levels of gene expression and protein synthesis, and contain binding sites and regulatory sequences to co-ordinate the activities of proteins involved in chromosome repair and maintenance. In addition, it is becoming increasingly clear that yet another level of information is encoded by the bacterial chromosome - the three-dimensional packaging of the chromosomal DNA molecule itself and its positioning relative to the cell. This vast structural blueprint of specific positional information is manifested in various ways, directing chromosome compaction, accessibility, attachment to the cell envelope, supercoiling, and general architecture and arrangement of the chromosome relative to the cell body. Recent studies have begun to identify and characterize novel systems that utilize the three-dimensional spatial information encoded by chromosomal architecture to co-ordinate and direct fundamental cellular processes within the cytoplasm, providing large-scale order within the complex clutter of the cytoplasmic compartment.

Positional Information by Differential Endocytosis Splits Auxin Response to Drive Arabidopsis Root Meristem Growth

In the Arabidopsis root meristem, polar auxin transport creates a transcriptional auxin response gradient that peaks at the stem cell niche and gradually decreases as stem cell daughters divide and differentiate [1-3]. The amplitude and extent of this gradient are essential for both stem cell maintenance and root meristem growth [4, 5]. To investigate why expression of some auxin-responsive genes, such as the essential root meristem growth regulator BREVIS RADIX (BRX) [6], deviates from this gradient, we combined experimental and computational approaches. We created cellular-level root meristem models that accurately reproduce distribution of nuclear auxin activity and allow dynamic modeling of regulatory processes to guide experimentation. Expression profiles deviating from the auxin gradient could only be modeled after intersection of auxin activity with the observed differential endocytosis pattern and positive autoregulatory feedback through plasma-membrane-to-nucleus transfer of BRX. Because BRX is required for expression of certain auxin response factor targets, our data suggest a cell-type-specific endocytosis-dependent input into transcriptional auxin perception. This input sustains expression of a subset of auxin-responsive genes across the root meristem's division and transition zones and is essential for meristem growth. Thus, the endocytosis pattern provides specific positional information to modulate auxin response.

Providing Positional Information with Active Transport on Dynamic Microtubules

Microtubules (MTs) are dynamic protein polymers that change their length by switching between growing and shrinking states in a process termed dynamic instability. It has been suggested that the dynamic properties of MTs are central to the organization of the eukaryotic intracellular space, and that they are involved in the control of cell morphology, but the actual mechanisms are not well understood. Here, we present a theoretical analysis in which we explore the possibility that a system of dynamic MTs and MT end-tracking molecular motors is providing specific positional information inside cells. We compute the MT length distribution for the case of MT-length-dependent switching between growing and shrinking states, and analyze the accumulation of molecular motors at the tips of growing MTs. Using these results, we show that a transport system consisting of dynamic MTs and associated motor proteins can deliver cargo proteins preferentially to specific positions within the cell. Comparing our results with experimental data in the model organism fission yeast, we propose that the suggested mechanisms could play important roles in setting length scales during cellular morphogenesis.

Reparative mechanisms in the cerebellar cortex

In the adult brain, different neuronal populations display different degrees of plasticity. Here, we describe the highly different plastic properties of inferior olivary neurones and Purkinje cells. Olivary neurones show a basal expression of growth-associated proteins, such as GAP-43 and Krox24/EGR-1, and remarkable remodelling capabilities of their terminal arbour. They also regenerate their transected neurites into growth-permissive territories and may reinnervate the lost target. Sprouting and regrowing olivary axons are able to follow specific positional information cues to establish new connections according to the original projection map. In addition, they set a strong cell body reaction to injury, which in specific olivary subsets is regulated by inhibitory target-derived cues. In contrast, Purkinje cells do not have a constitutive level of growth-associated genes, and show little cell body reaction, no axonal regeneration after axotomy, and weak sprouting capabilities. Block of myelin-derived signals allows terminal arbour remodelling, but not regeneration, while selective over-expression of GAP-43 induces axonal sprouting along the axonal surface and at the level of the lesion. We suggest that the high constitutive intrinsic plasticity of the inferior olive neurones allows their terminal arbour to sustain the activity-dependent ongoing competition with the parallel fibres in order to maintain the post-synaptic territory, and possibly underlies mechanisms of learning and memory. Such a plasticity is used also as a reparative mechanism following axotomy. In contrast, in Purkinje cells, poor intrinsic regenerative capabilities and myelin-derived signals stabilise the mature connectivity and prevent axonal regeneration after lesion.

On the structural complexity of simple biosystems

Quantitative formulations of the concepts of structural complexity, order and regularity in biological systems are proposed. Structural complexity is defined as the minimal number of numerical specifications required to describe an object in physical space. A tentative set of rules to calculate the complexity of point systems (like simple or complex molecules) in real space is formulated. The structural complexity of the following molecules and biostructures is calculated in detail: methane, ethane, adenine, the nucleosome and the Tobacco Mosaic Virus. While the total complexity of the structures increases with the number of atomic or molecular elements, the relative complexity is found to be correlated with the coding requirements for the molecule or the molecular assembly. It is proposed to apply complexity analysis for assessing the coding requirements of biological structures, with the aim of determining whether self assembly processes are sufficient for producing particular structures, or whether specific positional information, provided by the genome of the organism, can be expected to participate in the morphogenetic process. A tentative rule for making that distinction is offered.

Segregation during ascidian embryogenesis of egg cytoplasmic information for tissue-specific enzyme development.

Cleavage-arrested embryos of the ascidian Ciona intestinalis were able to differentiate two tissue-specific enzymes-muscle acetylcholinesterase (EC 3.1.1.7) and brain pigment cell tyrosinase (EC 1.10.3.1). Cytochalasin B, colchicine, Colcemid, and podophyllotoxin were used as cleavage inhibitors at early embryonic stages up to the 64-cell stage. Only certain cells in the cleavage-arrested embryos developed these histochemically detectable enzymes, and this ability followed the cell lineage patterns for the two tissues. This result implies the presence of specific positional information in the egg cytoplasm that is differentially segregated during cleavage. There were distinct and separate puromycin and actinomycin D sensitivity periods for the occurrence of each enzyme during development of both normal and cleavage-arrested embryos. The segregated information is apparently neither the enzyme proteins nor RNA templates for enzyme synthesis, but is probably concerned with activation of appropriate genes.