276 research outputs found

    Real-Time Digital Video Streaming at Low-VHF for Compact Autonomous Agents in Complex Scenes

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    This paper presents an experimental investigation of real-time digital video streaming in physically complex Non-Line-Of-Sight (NLoS) channels using a low-power, low-VHF system integrated on a compact robotic platform. Reliable video streaming in NLoS channels over infrastructure-poor ad-hoc radio networks is challenging due to multipath and shadow fading. In this effort, we focus on exploiting the near-ground low-VHF channel which has been shown to have improved penetration, reduced fading, and lower power requirements (which is critical for autonomous agents with limited power) compared to higher frequencies. Specifically, we develop a compact, low-power, low-VHF radio test-bed enabled by recent advances in efficient miniature antennas and off-the-shelf software-defined radios. Our main goal is to carry out an empirical study in realistic environments of how the improved propagation conditions at low-VHF affect the reliability of video-streaming with constraints stemming from the limited available bandwidth with electrically small low-VHF antennas. We show quantitative performance analysis of video streaming from a robotic platform navigating inside a large occupied building received by a node located outdoors: bit error rate (BER) and channel-induced Peak Signal-to-Noise Ratio (PSNR) degradation. The results show channel-effect-free-like video streaming with the low-VHF system in complex NLoS channels.Comment: Accepted for publication in 2019 IEEE 89th Vehicular Technology Conferenc

    Study of role of blood transfusion in obstetric emergencies

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    Background: Blood Transfusion is recognized as one of the eight essential component of comprehensive emergency obstetric care which has been shown to reduce the maternal mortality.1,2 In developing country like India, efforts should be done to make blood and transfusion services well maintained and quickly available to reduce maternal morbidity from haemorrhage and thus decrease the incidence of maternal mortality. Aims & objectives: (1) To study clinical status of the patients at time of admission. (2) To study the role of antenatal visits in all patients required blood transfusion. (3) To study the effect of blood components on the patients’ health. (4) To screen out the patients of high risk pregnancy and treat them safely. (5) To study causes of maternal mortality.Methods: Retrospective study of requirement of blood transfusion in antenatal and postnatal patients who came in labour room during last 3 month period at tertiary care Centre, Ahmedabad.Results: during the whole study out of 2200 patients 440 patients required blood transfusion among which 70% required due to obstetric hemorrhage and 30% due to severe anemia (less than 7 gm/dl). Major associated complications in the transfused patients were anemia (34%) and PPH (36%). 4 patients expired among them 2 were due to development of DIC and septicemia, 1 due to severe anemia and 1 due to severe PPH.Conclusions: Ensuring a safe supply of blood and blood products and the appropriate and rational clinical use of blood. Strategies made to maximize the haemoglobin (Hb) level at the time of delivery as well as to minimize blood loss. Active management of the third stage of labour is required to prevent avoidable morbidities, such as PPH, Retained product of conception, and vaginal lacerations.

    Using Pupillometry to Characterize Visual Perception in Autistic Mouse Models

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    Fragile X syndrome (FXS) is the leading genetic cause of autism. Individuals with Fragile X Syndrome (FXS) commonly display social, behavioral, and intellectual disabilities. Perceptual deficits and their underlying neural activity remain poorly characterized in FXS and other autism spectrum disorders (ASD’s). To explore visual perception in autism, we developed camera based pupil tracking software using OpenCV (an open-source computer vision library) capable of measuring visually evoked changes in pupil area and position in the FXS mouse model (Fmr1 KO). Changes in pupil area and position are believed to correlate with changes in arousal or visual processing and may serve as an indirect readout of brain state. To explore visually evoked changes in pupil area, head-restrained wild type or Fragile X mice were exposed to visual stimulation consisting of sinusoidal gratings. The average pupil area of Fragile X mice was increased compared to wild type controls. Our results suggest that online pupillometry has a high potential to serve as a diagnostic tool for autism spectrum disorders

    Hypertonic saline increases lung epithelial lining fluid glutathione and thiocyanate: two protective CFTR-dependent thiols against oxidative injury

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    <p>Abstract</p> <p>Background</p> <p>Cystic fibrosis is a debilitating lung disease due to mutations in the cystic fibrosis transmembrane conductance regulator protein (CFTR) and is associated with chronic infections resulting in elevated myeloperoxidase activity and generation of hypochlorous acid (HOCl). CFTR mutations lead to decreased levels of glutathione (GSH) and thiocyanate (SCN) in the epithelial lining fluid (ELF). Hypertonic saline is used to improve lung function however the mechanism is uncertain.</p> <p>Methods</p> <p>In the present study, the effect of GSH and SCN on HOCl-mediated cell injury and their changes in the ELF after hypertonic saline nebulization in wild type (WT) and CFTR KO mice was examined. CFTR sufficient and deficient lung cells were assessed for GSH, SCN and corresponding sensitivity towards HOCl-mediated injury, in vitro.</p> <p>Results</p> <p>CFTR (-) cells had lower extracellular levels of both GSH and SCN and were more sensitive to HOCl-mediated injury. In vivo, hypertonic saline increased ELF GSH in the WT and to a lesser extent in the CFTR KO mice but only SCN in the WT ELF. Finally, potential protective effects of GSH and SCN at concentrations found in the ELF against HOCl toxicity were examined in vitro.</p> <p>Conclusions</p> <p>While the concentrations of GSH and SCN associated with the WT ELF protect against HOCl toxicity, those found in the CFTR KO mice were less sufficient to inhibit cell injury. These data suggests that CFTR has important roles in exporting GSH and SCN which are protective against oxidants and that hypertonic saline treatment may have beneficial effects by increasing their levels in the lung.</p

    Role of doppler in fetal growth restriction

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    Background: Fetal growth restriction is an important and particularly challenging problem for modern obstetricians and paediatricians. The present study is to correlate the importance of Doppler velocimetry and perinatal outcome in cases of growth restricted foetuses by comparing perinatal outcome of control & study groups with normal and abnormal Doppler waveforms.Methods: A study and a control group comprising of 50 pregnant women having growth restricted foetuses in each group was matched for all other confounding factors except for Doppler changes. These patients were followed up and the perinatal outcomes of FGR foetuses having Doppler changes was compared with those having normal Doppler studies.Results: In our study, alteration in both MCA and UmbA Doppler was associated with perinatal morbidity and NICU admissions in 64% and mortality in 28%. Doppler changes showing altered CPR less than 1 had adverse outcome with NICU admission in 61% and mortality in 34%. Alteration in DV Doppler was associated with perinatal morbidity and NICU admissions in 17% cases and mortality in 83% cases, with no pregnancies having a healthy outcome. Among high-risk pregnancies with suspected IUGR, the use of Doppler assessment significantly decreases the likelihood of labor induction, caesarean delivery, and perinatal deaths.Conclusions: Abnormal Doppler waveform changes indicate adverse perinatal outcome of pregnancies with FGR. Doppler study helps to reduce perinatal mortality and morbidity by timely and appropriate interventions

    Improved deformation behavior in Ti-Zr-Fe-Mn alloys comprising the C14 type Laves and β phases

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    Laves phase alloys are promising materials for several structural applications, but the extreme brittleness is the predominant shortcoming of a Laves matrix. One potential solution to overcome this shortcoming is to alloy Laves matrix with some soft matrix. A group of Ti-35Zr-5Fe-xMn (x = 0, 2, 4, 6, 8 wt%) alloys was cast with an aim to improve deformation in Laves alloy compositions. The phase and microstructure analyses reveal dual phase matrices, including a β phase and a C14 type Laves phase in the investigated alloys. The mechanical properties such as yield strength, hardness and plastic strain for the investigated alloys are found to be significantly sensitive to volume fraction of the Laves phase. Ti-35Zr-5Fe shows impressive ultimate compressive strength (~1.7 GPa), yield strength (1138 MPa) and large plastic strain (23.2 %). The fracture mechanisms are dependent on the microstructure of the alloys. Additionally, the work-hardening ability of the investigated alloys have also been evaluated based on the analyses of slip band patterns formed around the micro-hardness indentations. Notably, the extreme brittleness is not encountered in all the Ti-35Zr-5Fe-xMn alloys and all exhibit very good compressive elongation including the maximum (32.5 %) in Ti-35Zr-5Fe

    Analytic Shielding Optimization to Reduce Crew Exposure to Ionizing Radiation Inside Space Vehicles

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    A sustainable lunar architecture provides capabilities for leveraging out-of-service components for alternate uses. Discarded architecture elements may be used to provide ionizing radiation shielding to the crew habitat in case of a Solar Particle Event. The specific location relative to the vehicle where the additional shielding mass is placed, as corroborated with particularities of the vehicle design, has a large influence on protection gain. This effect is caused by the exponential- like decrease of radiation exposure with shielding mass thickness, which in turn determines that the most benefit from a given amount of shielding mass is obtained by placing it so that it preferentially augments protection in under-shielded areas of the vehicle exposed to the radiation environment. A novel analytic technique to derive an optimal shielding configuration was developed by Lockheed Martin during Design Analysis Cycle 3 (DAC-3) of the Orion Crew Exploration Vehicle (CEV). [1] Based on a detailed Computer Aided Design (CAD) model of the vehicle including a specific crew positioning scenario, a set of under-shielded vehicle regions can be identified as candidates for placement of additional shielding. Analytic tools are available to allow capturing an idealized supplemental shielding distribution in the CAD environment, which in turn is used as a reference for deriving a realistic shielding configuration from available vehicle components. While the analysis referenced in this communication applies particularly to the Orion vehicle, the general method can be applied to a large range of space exploration vehicles, including but not limited to lunar and Mars architecture components. In addition, the method can be immediately applied for optimization of radiation shielding provided to sensitive electronic components
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