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Accurate and robust extrinsic calibration is necessary for deploying autonomous systems which need multiple sensors for perception. In this letter, we present a robust system for real-time extrinsic calibration of multiple lidars in vehicle base framewithout the need for any fiducialmarkers or features. We base our approach on matching absolute GNSS (Global Navigation Satellite System) and estimated lidar poses in real-time. Comparing rotation components allows us to improve the robustness of the solution than traditional least-square approach comparing translation components only. Additionally, instead of comparing all corresponding poses, we select poses comprising maximum mutual information based on our novel observability criteria. This allows us to identify a subset of the poses helpful for real-time calibration. We also provide stopping criteria for ensuring calibration completion. To validate our approach extensive tests were carried out on data collected using Scania test vehicles (7 sequences for a total of approximate to 6.5 Km). The results presented in this letter show that our approach is able to accurately determine the extrinsic calibration for various combinations of sensor setups., QC 20230508

Male infertility is a global public health concern. Teratozoospermia is a qualitative anomaly of spermatozoa morphology, contributing significantly to male infertility, whereas azoospermia is the complete absence of spermatozoa in the ejaculate. Thus, there is a serious need for unveiling the common origin and/or connection between both of these diseases, if any. This study aims to identify common potential biomarker genes of these two diseases via an in silico approach using a meta-analysis of microarray data. In this study, a differential expression analysis of genes was performed on four publicly available RNA microarray datasets, two each from teratozoospermia (GSE6872 and GSE6967) and azoospermia (GSE145467 and GSE25518). From the analysis, 118 DEGs were found to be common to teratozoospermia and azoospermia, and, interestingly, sperm autoantigenic protein 17 (SPA17) was found to possess the highest fold change value among all the DEGs (9.471), while coiled-coil domain-containing 90B (CCDC90B) and coiled-coil domain-containing 91 (CCDC91) genes were found to be common among three of analyses, i.e., Network Analyst, ExAtlas, and GEO2R. This observation indicates that SPA17, CCDC90B, and CCDC91 genes might have significant roles to play as potential biomarkers for teratozoospermia and azoospermia. Thus, our study opens a new window of research in this area and can provide an important theoretical basis for the diagnosis and treatment of both these diseases., info:eu-repo/semantics/openAccess

We propose ReDense as a simple and low complexity way to improve the performance of trained neural networks. We use a combination of random weights and rectified linear unit (ReLU) activation function to add a ReLU dense (ReDense) layer to the trained neural network such that it can achieve a lower training loss. The lossless flow property (LFP) of ReLU is the key to achieve the lower training loss while keeping the generalization error small. ReDense does not suffer from vanishing gradient problem in the training due to having a shallow structure. We experimentally show that ReDense can improve the training and testing performance of various neural network architectures with different optimization loss and activation functions. Finally, we test ReDense on some of the state-of-the-art architectures and show the performance improvement on benchmark., Part of proceedings: ISBN 978-1-7281-7605-5, QC 20230118

We present an efficient multi-sensor odometry system for mobile platforms that jointly optimizes visual, lidar, and inertial information within a single integrated factor graph. This runs in real-time at full framerate using fixed lag smoothing. To perform such tight integration, a new method to extract 3D line and planar primitives from lidar point clouds is presented. This approach overcomes the suboptimality of typical frame-to-frame tracking methods by treating the primitives as landmarks and tracking them over multiple scans. True integration of lidar features with standard visual features and IMU is made possible using a subtle passive synchronization of lidar and camera frames. The lightweight formulation of the 3D features allows for real-time execution on a single CPU. Our proposed system has been tested on a variety of platforms and scenarios, including underground exploration with a legged robot and outdoor scanning with a dynamically moving handheld device, for a total duration of 96 min and 2.4 km traveled distance. In these test sequences, using only one exteroceptive sensor leads to failure due to either underconstrained geometry (affecting lidar) or textureless areas caused by aggressive lighting changes (affecting vision). In these conditions, our factor graph naturally uses the best information available from each sensor modality without any hard switches., QC 20210324

Spiders are one of the most diverse and numerically abundant arthropods. They have a wide distribution and inhabit different types of habitats. Their occurrence and distribution function as a bio-indicator of that area and their presence is influenced greatly by the corresponding habitat and vegetation types. In this study the spider fauna was surveyed from November 2019 to October 2020 in three locations of Kailashahar, Tripura, India. A total of thirty-two species belonging to thirteen families and eighteen genera were identified. Among them nine species are reported for the first time in Tripura, India - Neogeo nocticolor, Tetragnatha mandibulata, Tetragnatha javana, Enoplognatha sp., Oxytate sp., Carrhotus viduus, Thalassius albocinctus, Scytodes fusca and Mimetus sp. The highest numerically abundant spider recorded is Oxyopes scalaris and the least abundant species is Opadometa fastigata in the study area. The present study thoroughly investigated the unexplored spider species distributed over the study area and highlights the richness of spider diversity while calling for greater conservation of forest areas. Further rigorous works are necessary to discover more new spider species from this unexplored state of northeast India., info:eu-repo/semantics/openAccess

Polarization handling in suspended silicon photonics has the potential to enable new applications in fields such as optomechanics, photonic microelectromechanical systems, and mid-infrared photonics. In this work, we experimentally demonstrate a suspended polarization beam splitter on a silicon-on-insulator waveguide platform, based on an asymmetric directional coupler. Our device presents polarization extinction ratios above 10 and 15 dB, and insertion losses below 5 and 1 dB, for TM and TE polarized input, respectively, across a 40 nm wavelength range at 1550 nm, with a device length below 8 µm. These results make our suspended polarization beam splitter a promising building block for future systems based on polarization diversity suspended photonics., QC 20180206, vr-het