MIMO MC-CDMA systems over indoor optical wireless communication channels

Optical wireless communication systems offer a number of advantages over their radio frequency counterparts. The advantages include freedom from fading, freedom from spectrum regulations and abundant bandwidth. The main limitations of optical wireless systems include background noise attributed to natural and artificial light sources and multipath propagation. The former degrades the signal to noise ratio while the latter limits the maximum achievable data rate. This thesis investigates the use of transmit power adaptation in the design of optical wireless spot-diffusing systems to increase the power associated with the main impulse response components, resulting in a compact impulse response and a system that is able to achieve higher data rates. The work also investigates the use of imaging diversity receivers that can reject the background noise components received in directions not associated with the signal. The two techniques help improve the optical wireless system performance. The multibeam transmitter and the multi-detector angle diversity receiver or imaging receiver form a multiple input multiple output (MIMO) system. The work also investigates additional methods that can improve the performance such as transmitter beam angle adaptation, and improved modulation and coding in the form of multi-carrier code division multiple access (MC-CDMA). Furthermore, the work investigates the robustness of a link design that adopts the combination of these methods in a realistic environment with full mobility.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Cathode Active Material Recycling from Spent Lithium Batteries: A Green (Circular) Approach Based on Deep Eutectic Solvents

The transition to a circular economy vision must handle the increasing request of metals required to satisfy the battery industry; this can be obtained by recycling and feeding back secondary raw materials recovered through proper waste management. Here, a novel and green proof-of-concept was developed, based on deep eutectic solvents (DESs) to fully and easily recover valuable metals from various cathode active materials, including LiMn2O4, LiNi0.5Mn1.5O4, and LiNi0.8Co0.2O2. DES composed of choline chloride and lactic acid could leach Li, Mn, Co, and Ni, achieving efficiency of 100 % under much milder conditions with respect to the previous literature. For the first time, to our best knowledge, a two-step approach was reported in the case of LiNi0.8Co0.2O2 for selective recovery of Li, Co, and Ni with high yield and purity. Furthermore, other cathode components, namely aluminum current collector and binder, were found to be not dissolved by the proposed DES, thus making a simple separation from the active material possible. Finally, this strategy was designed to easily regenerate and reuse the leaching solvents for more than one extraction, thus further boosting process sustainability

ISOLATION, IDENTIFICATION AND ANTIMICROBIAL ACTIVITY OF BIOACTIVE COMPOUND FROM SARACA ASOCA

Objective: Saraca asoca which is also called Saraca indica is the ancient tree of the family Caesalpinaceae. This tree is considered as the first in medicinal values since the Buddist period. Ashoka is traditionally used in the treatment of excessive uterine bleeding, dysmenorrhoea and depression in women. It is also used to treat inflammation, indigestion and also abnormal vaginal discharge. It is found to have antimicrobial, anticancer, antimenorrhagic, anti oxytocic activities. The study focuses on to isolate and characterizes the bioactive compounds from the leaves of Saraca asoca by cold extraction method. Methods: The crude extracts of ethanol, petroleum ether, and aqueous extracts were spotted in TLC plate to fig. out the number of probable compounds in each extract. Column chromatography was performed to collect purified fractions. Phytochemical screening of crude samples were tested, the presence of flavonoids, steroids, tannins, alkaloids, glycosides, phenols, reducing sugars were identified. Antimicrobial activity of ethanol, petroleum ether fractions were tested using agar-well diffusion method, maximum activity was recorded in a concentration-dependent manner against Escherichia coli, Staphylococcus sp, Streptococcus sp, Pseudomonas sp, Proteus sp, Bacillus sp, Aspergillus sp and Candida sp. Results: Among the total fractions obtained, few active fractions inhibited growth of organisms which would significantly serve as a potential source for new antimicrobial compounds. GCMS was performed to identify the potential compound to be Phytol exhibiting antimicrobial activity. Conclusion: The antimicrobial activity of the bioactive compounds was tested against various microorganisms and the diameter of the zone obtained was calculated where the petroleum ether fractions exhibited good inhibition and ethanolic fractions does not have inhibitory activity

Efficacy, Safety, and Timing of Anticoagulant Thromboprophylaxis for the Prevention of Venous Thromboembolism in Patients With Acute Spinal Cord Injury: A Systematic Review

Study Design: Systematic review. Objectives: The objective of this study was to answer 5 key questions: What is the comparative effectiveness and safety of (1a) anticoagulant thromboprophylaxis compared to no prophylaxis, placebo, or another anticoagulant strategy for preventing deep vein thrombosis (DVT) and pulmonary embolism (PE) after acute spinal cord injury (SCI)? (1b) Mechanical prophylaxis strategies alone or in combination with other strategies for preventing DVT and PE after acute SCI? (1c) Prophylactic inferior vena cava filter insertion alone or in combination with other strategies for preventing DVT and PE after acute SCI? (2) What is the optimal timing to initiate and/or discontinue anticoagulant, mechanical, and/or prophylactic inferior vena cava filter following acute SCI? (3) What is the cost-effectiveness of these treatment options? Methods: A systematic literature search was conducted to identify studies published through February 28, 2015. We sought randomized controlled trials evaluating efficacy and safety of antithrombotic strategies. Strength of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Results: Nine studies satisfied inclusion criteria. We found a trend toward lower risk of DVT in patients treated with enoxaparin. There were no significant differences in rates of DVT, PE, bleeding, and mortality between patients treated with different types of low-molecular-weight heparin or between low-molecular-weight heparin and unfractionated heparin. Combined anticoagulant and mechanical prophylaxis initiated within 72 hours of SCI resulted in lower risk of DVT than treatment commenced after 72 hours of injury. Conclusion: Prophylactic treatments can be used to lower the risk of venous thromboembolic events in patients with acute SCI, without significant increase in risk of bleeding and mortality and should be initiated within 72 hours. © 2017, © The Author(s) 2017

Swept-Source Optical Coherence Tomography Biometer as Screening Strategy for Macular Disease in Patients Scheduled for Cataract Surgery

The aim of this study was to assess the central macular imaging captured with an optical biometer based on full-eye-length Swept-Source OCT (SS-OCT) scan as a screening strategy for identifying macular diseases in patients scheduled for cataract surgery. 1,114 eyes of 749 consecutive patients underwent a biometrical examination with IOLMaster 700 SS-OCT technology (Carl Zeiss) and conventional Spectral-Domain OCT (SD-OCT) (Spectralis OCT, Heidelberg) device analysis on the same day. Seven examiners graded the scans individually in a full-masked mode. Twenty-five eyes were excluded for media opacities. Among the 1,089 included eyes, statistical analysis revealed a mean Kendall\u2019s Coefficient of 0.83 (range 0.76\u20130.89). A logistic regression model demonstrated a highly significant correlation (p < 0.001) between the coefficient of concordance and SD-OCT imaging. Intraobserver reproducibility was 0.89 (range 0.86\u20130.91). Optical biometer SS-OCT scans showed a mean sensitivity of 0.81 and a mean specificity of 0.84. The positive and negative predictive value detected was 0.78 and 0.86, respectively. In order to predict the risk of reduced visual recovery, especially in cases of retinal pathology, optical biometer with SS-OCT scan has proven to be a useful modality for detecting macular structural abnormalities in patients undergoing cataract surgery. Conventional SD-OCT remains mandatory to confirm the presumed diagnosis

Glycine Receptor Antibody-Associated Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM) During SARS-CoV-2 Infection: a Video-Case Report

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In vivo antimicrobial activity of 0.6% povidone-iodine eye drops in patients undergoing intravitreal injections: a prospective study

To investigate the antimicrobial activity of a preservative-free 0.6% povidone-iodine eye drop as an antiseptic procedure in decreasing the conjunctival bacterial load in eyes scheduled for intravitreal treatment and to compare its efficacy to the untreated fellow eye used as the control group. Prospective cohort analysis in which 208 patients received preservative-free 0.6% povidone-iodine eye drops three times a day for three days before intravitreal injection. Before and after the prophylactic treatment, a conjunctival swab was collected from both the study eye and the untreated contralateral eye, used as control. The swab was inoculated on different culture media and the colony-forming units were counted. Bacteria and fungi were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Treatment with 0.6% povidone-iodine eye drops significantly reduced the conjunctival bacterial load from baseline (p &lt; 0.001 for blood agar and p &lt; 0.001 for chocolate agar) with an eradication rate of 80%. The most commonly isolated pathogen at each time-point and in both groups was coagulase-negative Staphylococci, isolated in 84% of the positive cultures. The study provides evidence about the effectiveness of 0.6% povidone-iodine eye drops treatment in reducing the conjunctival bacterial load in eyes scheduled for intravitreal treatment