671 research outputs found

    Vision-based range estimation using helicopter flight data

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    Pilot aiding during low-altitude flight depends on the ability to detect and locate obstacles near the helicopter's intended flightpath. Computer-vision-based methods provide one general approach for obstacle detection and range estimation. Several algorithms have been developed for this purpose, but have not been tested with actual flight data. This paper presents results obtained using helicopter flight data with a feature-based range estimation algorithm. A method for recursively estimating range using a Kalman filter with a monocular sequence of images and knowledge of the camera's motion is described. The helicopter flight experiment and four resulting datasets are discussed. Finally the performance of the range estimation algorithm is explored in detail based on comparison of the range estimates with true range measurements collected during the flight experiment

    The Role of Specific Integrase Strand Transfer Inhibitors (INSTIs) in the Alteration of Oligodendrocyte Maturation and Myelination in Hand

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    Currently, thirty-seven million people are infected with human immunodeficiency virus-1 (HIV-1) worldwide. Thankfully, the development of combined antiretroviral therapy (cART) regimens has decreased mortality and significantly improved the overall quality of life for these patients. However, approximately half of all patients clinically manifest with HIV-associated neurocognitive disorder (HAND), a spectrum of cognitive, motor, and behavioral abnormalities which histologically present as non-specific gliosis, synaptodendritc damage and loss of white matter and myelin. Furthermore, the severity of white matter damage correlates with the length of ART duration. However, almost no studies have been performed to determine how the myelin sheath or the oligodendrocytes that synthesize the sheath are damaged. Thus, we hypothesized that the administration of ART contributed in part to the myelin loss in the CNS of HIV-positive patients. Previously, we have reported that the protease inhibitor class of ART drugs hampered the in vitrodifferentiation of oligodendrocytes. Given that the new US guidelines for treating HIV patients recommends anew class of drugs, the integrasestrand transferinhibitors(INSTIs)as front-line therapy, we examined if two specific INSTIs, Elvitegravir (EVG) and raltegravir (RAL), altered the survival and/or maturation of developing oligodendrocytes in vitroand in vivo. We found that treatment of oligodendrocyte precursor cells (OPCs) with EVG, but not RAL, during differentiation reduced the number of cells positive for immature oligodendrocyte marker galactosylceramide (GalC) and mature oligodendrocyte marker myelin basic protein (MBP) in vitro, as well as the synthesis of myelin proteins. However, neither EVG or RAL induced cell loss or apoptosis, as determined by cell counts and TUNEL assays, suggesting that EVG does not affect OPC viability but instead, inhibits differentiation. EVG-induced oligodendrocyte differentiation deficits could be reversed by pre-treating the cells with a drug that pharmacologically inhibits the phosphorylation of eukaryotic initiation factor 2α(eIF2α) throughthe cellular integrated stress response (ISR). Finally, in vivo,mice receiving EVG/COBI failed to remyelinate the corpus callosum during the three week recovery period following demyelination, after cuprizone treatment. Although EVG/COBI treatment by itself did not cause overt white matter loss in this brain region. Our study demonstrates that EVG, but not RAL, inhibits oligodendrocyte precursor cell differentiation both in vitroand in vivo. Furthermore, EVG may be inhibiting oligodendrocyte precursor cell differentiation though activation of the ISR. Also, we found thatthe effects of EVG on oligodendrocyte differentiation could be attenuated in vitroby inhibiting the ISR. These studies suggest that ART may contribute to cognitive impairment by inhibiting renewal and replacement of oligodendrocytes in adults or development of oligodendrocytes in children. Further, our results suggest an ISR inhibitor might attenuate the negative effect of EVG on the maturation of oligodendrocytes. Our findings also suggest that development of less toxic ART compounds and adjunctive therapies are needed to minimize the side effects of ART on the CNS

    Impact Resisting Concrete

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    Different percentages of polymers have been added to concrete, to evaluate its  impact resistance. Mixes have been made for plain concrete with crushed stone, also plain concrete mixes with round gravel, Concrete mixes with (0.2, 0.85, 1.5 and 2.0) % of Melment to 100 Kg of binder, Concrete mixes with (0.2, 0.5, 0.75 and 1.5) liter of Glenium to 100 Kg of cement and concrete mixes with three sheets of polystyrene and concrete mixes made using polystyrene sheets with 0.85% by weight of Melment. Concrete with polystyrene sheets and Melment gives average compressive strength of 59.3Mpa, tensile strength of 5.8 Mpa and impact strength when the first crack appears was 1486 blows at 28 days. Using 0.85 % of Melment per 100Kg of binder enhance the concrete resistance to Impact. Using 0.5 Liter of Glenium per 100Kg of cement shows good performance of concrete to Impact. Using three layers of Polystyrene sheets with 0.85% of Melment gives high compressive strength and improve the Impact capacity of concrete. Polystyrene sheets increases the adhesive forces between materials in the mix and superplasticizers increases the workability so as to produce self compacting concrete. Keywords: Polystyrene, Melment, Glenium, Impact Strength. Self Compacting Concrete

    Cloned defective interfering influenza virus protects ferrets from pandemic 2009 influenza A virus and allows protective immunity to be established

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    Influenza A viruses are a major cause of morbidity and mortality in the human population, causing epidemics in the winter, and occasional worldwide pandemics. In addition there are periodic outbreaks in domestic poultry, horses, pigs, dogs, and cats. Infections of domestic birds can be fatal for the birds and their human contacts. Control in man operates through vaccines and antivirals, but both have their limitations. In the search for an alternative treatment we have focussed on defective interfering (DI) influenza A virus. Such a DI virus is superficially indistinguishable from a normal virus but has a large deletion in one of the eight RNAs that make up the viral genome. Antiviral activity resides in the deleted RNA. We have cloned one such highly active DI RNA derived from segment 1 (244 DI virus) and shown earlier that intranasal administration protects mice from lethal disease caused by a number of different influenza A viruses. A more cogent model of human influenza is the ferret. Here we found that intranasal treatment with a single dose of 2 or 0.2 µg 244 RNA delivered as A/PR/8/34 virus particles protected ferrets from disease caused by pandemic virus A/California/04/09 (A/Cal; H1N1). Specifically, 244 DI virus significantly reduced fever, weight loss, respiratory symptoms, and infectious load. 244 DI RNA, the active principle, was amplified in nasal washes following infection with A/Cal, consistent with its amelioration of clinical disease. Animals that were treated with 244 DI RNA cleared infectious and DI viruses without delay. Despite the attenuation of infection and disease by DI virus, ferrets formed high levels of A/Cal-specific serum haemagglutination-inhibiting antibodies and were solidly immune to rechallenge with A/Cal. Together with earlier data from mouse studies, we conclude that 244 DI virus is a highly effective antiviral with activity potentially against all influenza A subtypes

    Heterogeneity in Phenotype of Usher-Congenital Hyperinsulinism Syndrome:Hearing Loss, Retinitis Pigmentosa, and Hyperinsulinemic Hypoglycemia Ranging from Severe to Mild with Conversion to Diabetes

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    OBJECTIVE: To evaluate the phenotype of 15 children with congenital hyperinsulinism (CHI) and profound hearing loss, known as Homozygous 11p15-p14 Deletion syndrome (MIM #606528). RESEARCH DESIGN AND METHODS: Prospective clinical follow-up and genetic analysis by direct sequencing, multiplex ligation-dependent probe amplification, and microsatellite markers. RESULTS: Genetic testing identified the previous described homozygous deletion in 11p15, USH1C:c.(90+592)_ABCC8:c.(2694–528)del. Fourteen patients had severe CHI demanding near-total pancreatectomy. In one patient with mild, transient neonatal hypoglycemia and nonautoimmune diabetes at age 11 years, no additional mutations were found in HNF1A, HNF4A, GCK, INS, and INSR. Retinitis pigmentosa was found in two patients aged 9 and 13 years. No patients had enteropathy or renal tubular defects. Neuromotor development ranged from normal to severe delay with epilepsy. CONCLUSIONS: The phenotype of Homozygous 11p15-p14 Deletion syndrome, or Usher-CHI syndrome, includes any severity of neonatal-onset CHI and severe, sensorineural hearing loss. Retinitis pigmentosa and nonautoimmune diabetes may occur in adolescence

    Low dose influenza virus challenge in the ferret leads to increased virus shedding and greater sensitivity to oseltamivir

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    Ferrets are widely used to study human influenza virus infection. Their airway physiology and cell receptor distribution makes them ideal for the analysis of pathogenesis and virus transmission, and for testing the efficacy of anti-influenza interventions and vaccines. The 2009 pandemic influenza virus (H1N1pdm09) induces mild to moderate respiratory disease in infected ferrets, following inoculation with 106 plaque-forming units (pfu) of virus. We have demonstrated that reducing the challenge dose to 102 pfu delays the onset of clinical signs by 1 day, and results in a modest reduction in clinical signs, and a less rapid nasal cavity innate immune response. There was also a delay in virus production in the upper respiratory tract, this was up to 9-fold greater and virus shedding was prolonged. Progression of infection to the lower respiratory tract was not noticeably delayed by the reduction in virus challenge. A dose of 104 pfu gave an infection that was intermediate between those of the 106 pfu and 102 pfu doses. To address the hypothesis that using a more authentic low challenge dose would facilitate a more sensitive model for antiviral efficacy, we used the well-known neuraminidase inhibitor, oseltamivir. Oseltamivir-treated and untreated ferrets were challenged with high (106 pfu) and low (102 pfu) doses of influenza H1N1pdm09 virus. The low dose treated ferrets showed significant delays in innate immune response and virus shedding, delayed onset of pathological changes in the nasal cavity, and reduced pathological changes and viral RNA load in the lung, relative to untreated ferrets. Importantly, these observations were not seen in treated animals when the high dose challenge was used. In summary, low dose challenge gives a disease that more closely parallels the disease parameters of human influenza infection, and provides an improved pre-clinical model for the assessment of influenza therapeutics, and potentially, influenza vaccines

    Modelling microbiome recovery after antibiotics using a stability landscape framework

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    Treatment with antibiotics is one of the most extreme perturbations to the human microbiome. Even standard courses of antibiotics dramatically reduce the microbiome’s diversity and can cause transitions to dysbiotic states. Conceptually, this is often described as a ‘stability landscape’: the microbiome sits in a landscape with multiple stable equilibria, and sufficiently strong perturbations can shift the microbiome from its normal equilibrium to another state. However, this picture is only qualitative and has not been incorporated in previous mathematical models of the effects of antibiotics. Here, we outline a simple quantitative model based on the stability landscape concept and demonstrate its success on real data. Our analytical impulse-response model has minimal assumptions with three parameters. We fit this model in a Bayesian framework to data from a previous study of the year-long effects of short courses of four common antibiotics on the gut and oral microbiomes, allowing us to compare parameters between antibiotics and microbiomes, and further validate our model using data from another study looking at the impact of a combination of last-resort antibiotics on the gut microbiome. Using Bayesian model selection we find support for a long-term transition to an alternative microbiome state after courses of certain antibiotics in both the gut and oral microbiomes. Quantitative stability landscape frameworks are an exciting avenue for future microbiome modelling

    Associations between genetic variants in the vitamin d metabolism pathway and severity of covid-19 among uae residents

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    Vitamin D has many effects on cells in the immune system. Many studies have linked low vitamin D status with severity of COVID-19. Genetic variants involved in vitamin D metabolism have been implicated as potential risk factors for severe COVID-19 outcomes. This study investigated how genetic variations in humans affected the clinical presentation of COVID-19. In total, 646 patients with SARS-CoV-2 infection were divided into two groups: noncritical COVID-19 (n = 453; 70.12%) and a critical group (n = 193; 29.87%). Genotype data on the GC, NADSYN1, VDR, and CYP2R1 genes along with data on serum 25-hydroxyvitamin D levels were compiled in patients admitted to a major hospital in the United Arab Emirates between April 2020 and January 2021. We identified 12 single-nucleotide polymorphisms associated with the critical COVID-19 condition: rs59241277, rs113574864, rs182901986, rs60349934, and rs113876500; rs4944076, rs4944997, rs4944998, rs4944979, and rs10898210; and rs11574018 and rs11574024. We report significant associations between genetic determinants of vitamin D metabolism and COVID-19 severity in the UAE population. Further research needed to clarify the mechanism of action against viral infection in vitamin D deficiency. These variants could be used with vaccination to manage the spread of SARS-CoV-2 and could be particularly valuable in populations in which vitamin D deficiency is common

    Case report: Restrictive cardiomyopathy presenting with complete thromboembolism occlusion of the terminal part of the abdominal aorta in a preadolescent Saudi girl

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    Restrictive cardiomyopathy (RCM) is a rare disease in children, accounting for <5% of all pediatric cardiomyopathies. It may be idiopathic or may be a secondary to a systemic disease. The disease is characterized by normal systolic function with impaired ventricular filling caused by stiff ventricular walls. Children with RCM often present with symptoms of exercise intolerance, shortness of breath, weakness, and chest discomfort. Thromboembolism events are an unusual presentation of RCM. We are reporting a preadolescent female from the eastern province of Saudi Arabia who presented with sudden right lower limb swelling, paresthesia, and pain caused by a complete occlusion of the terminal part of the abdominal aorta and both common iliac arteries. Echocardiography revealed dilated atria, normal ventricle dimensions and two floating thrombi in the left atrium. The patient was successfully managed with an anticoagulant, surgical thrombectomy and cardiac transplantation
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