321 research outputs found

    Self-Navigation Car using Reinforcement Learning

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    In this paper, a project is described which is a 2-D modelled version of a car that will learn how to drive itself. It will have to figure everything out on its own. In addition, to achieve that the simulator contains a car running simultaneously &can be controlled by different control algorithms - heuristic, reinforcement learning-based, etc. For each dynamic input, the Reinforcement- Learning modifies new patterns. Ultimately, Reinforcement Learning helps in maximizing the reward from every state. In this first Part, we will implement a Reinforcement-Learning model to build an AI for Self Driving Car. Project will be focusing on the brain of the car not any graphics. The car will detect obstacles and take basic actions. To make autonomous car or self-driving car a reality, some of the factors to be considered are human safety and quality of life

    Seasonality and outbreak of a predominant Streptococcus pneumoniae serotype 1 clone from The Gambia: Expansion of ST217 hypervirulent clonal complex in West Africa

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    BACKGROUND: Streptococcus pneumoniae serotype 1 causes > 20% of invasive disease, among all age groups combined, in The Gambia. In contrast, it is rarely detected in carriage studies. This study compares the molecular epidemiology of S. pneumoniae serotype 1 causing invasive disease in The Gambia between 1996 and 2005 to those carried in the nasopharynx between 2004 and 2006. RESULTS: A total of 127 invasive and 36 nasopharyngeal carriage serotype 1 isolates were recovered from individuals of all age groups and were analyzed by serotyping, antibiotic susceptibility testing and MLST. MLST analysis revealed 23 different sequence types (STs), 18 of which were novel. The most prevalent clone among the 163 isolates was ST618 (70.5%), followed by ST3575 (7.4%), ST2084 (2.5%) and ST612 (2.5%). A single ST (ST618), previously shown to belong to the ST217 hypervirulent clonal complex, was frequent among carriage (61.1%) and invasive (72.7%) serotype 1 isolates. ST618 causing both paediatric and adult disease peaked annually in the hot dry season and caused outbreak in 1997 and 2002. CONCLUSION: For over a decade, isolates of ST618 have been the dominant lineage among serotype 1 carriage and disease isolates circulating in the Gambia. This lineage shows similar epidemiological features to those of the meningococcus in the African meningitis belt being able to cause outbreaks of disease

    Characterization of Asphalt Binders Exposed to Extreme Temperatures through Simple and Effective Test Methods

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    DTRT13-G-UTC36In the Arkansas State University (ASU) study, Superpave and Multiple Stress Creep and Recovery (MSCR) tests were performed to evaluate viscoelastic properties of selected asphalt binders approved in Arkansas and Texas. A total of 65 binder samples were tested in the laboratory. Of these, eight were unmodified binders, 24 were polymer-modified binders (PMBs), 27 were warm mix asphalt (WMA)-additive modified, and 6 were reclaimed asphalt pavement (RAP) modified binders. The non-recoverable compliance and MSCR percent recovery data of the tested binders were analyzed for grading and establishing the MSCR percent recovery criteria for local service temperature and traffic conditions. The developed guidelines are expected to be helpful for transportation agencies in Arkansas and Texas to adopt the MSCR test method in their quality control process. In the University of Oklahoma (OU) study, the polymer-modified binders were found to meet the Superpave\uae specifications and exhibited satisfactory rutting and fatigue resistance. The high- and low-temperature performance grade (PG) grades of the RAP binder blends were observed to increase with an increase in the RAP binder content. From the MSCR test results, the minimum %Recovery requirement based on the Jnr criteria suggested in American Association of State Highway and Transportation Officials (AASHTO) TP 70 was found to be appropriate for differentiating polymer-modified binders from non-polymer modified binders. Also, the addition of a higher stress level, such as 10 kPa to the MSCR test method, was found to help understand the nonlinear viscoelastic behavior of the polymer-modified binders. Furthermore, the Jnr value decreased and MSCR grades increased with an increase in the amount of RAP binder, which indicated an improved resistance to rutting for the RAP binder blends. The rutting and moisture susceptibilities of the asphalt mixes with high RAP content were found to be satisfactory from Hamburg Wheel Tracking (HWT) tests. A comparison of the Superpave\uae, MSCR and HWT test results is also presented in this report. In the Louisiana Tech University (LTU) study, the extensional deformation behavior of PG binders 58-28, PG 64-22, and PG 76-22 and its parameters including geometry and temperature were investigated through an extensional rheological approach using a Dynamic Shear Rheometer (DSR)-based Sentmanat Extensional Rheometer (SER). A test method and a sample preparation procedure for asphalt binders were developed as a replacement to the conventional force ductility test. With a more reproducible, significantly less material and time consuming, and with a more mechanistic approach, the developed novel test method can help improve the durability of modified asphalt pavements

    Impact of routine vaccination against Haemophilus influenzae type b in The Gambia: 20 years after its introduction.

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    BACKGROUND: In 1997, The Gambia introduced three primary doses of Haemophilus influenzae type b (Hib) conjugate vaccine without a booster in its infant immunisation programme along with establishment of a population-based surveillance on Hib meningitis in the West Coast Region (WCR). This surveillance was stopped in 2002 with reported elimination of Hib disease. This was re-established in 2008 but stopped again in 2010. We aimed to re-establish the surveillance in WCR and to continue surveillance in Basse Health and Demographic Surveillance System (BHDSS) in the east of the country to assess any shifts in the epidemiology of Hib disease in The Gambia. METHODS: In WCR, population-based surveillance for Hib meningitis was re-established in children aged under-10 years from 24 December 2014 to 31 March 2017, using conventional microbiology and Real Time Polymerase Chain Reaction (RT-PCR). In BHDSS, population-based surveillance for Hib disease was conducted in children aged 2-59 months from 12 May 2008 to 31 December 2017 using conventional microbiology only. Hib carriage survey was carried out in pre-school and school children from July 2015 to November 2016. RESULTS: In WCR, five Hib meningitis cases were detected using conventional microbiology while another 14 were detected by RT-PCR. Of the 19 cases, two (11%) were too young to be protected by vaccination while seven (37%) were unvaccinated. Using conventional microbiology, the incidence of Hib meningitis per 100?000-child-year (CY) in children aged 1-59 months was 0.7 in 2015 (95% confidence interval (CI)?=?0.0-3.7) and 2.7 (95% CI?=?0.7-7.0) in 2016. In BHDSS, 25 Hib cases were reported. Nine (36%) were too young to be protected by vaccination and five (20%) were under-vaccinated for age. Disease incidence peaked in 2012-2013 at 15 per 100?000 CY and fell to 5-8 per 100?000 CY over the subsequent four years. The prevalence of Hib carriage was 0.12% in WCR and 0.38% in BHDSS. CONCLUSIONS: After 20 years of using three primary doses of Hib vaccine without a booster Hib transmission continues in The Gambia, albeit at low rates. Improved coverage and timeliness of vaccination are of high priority for Hib disease in settings like Gambia, and there are currently no clear indications of a need for a booster dose

    An outbreak of pneumococcal meningitis among older children (≥5 years) and adults after the implementation of an infant vaccination programme with the 13-valent pneumococcal conjugate vaccine in Ghana.

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    BACKGROUND: An outbreak of pneumococcal meningitis among non-infant children and adults occurred in the Brong-Ahafo region of Ghana between December 2015 and April 2016 despite the recent nationwide implementation of a vaccination programme for infants with the 13-valent pneumococcal conjugate vaccine (PCV13). METHODS: Cerebrospinal fluid (CSF) specimens were collected from patients with suspected meningitis in the Brong-Ahafo region. CSF specimens were subjected to Gram staining, culture and rapid antigen testing. Quantitative PCR was performed to identify pneumococcus, meningococcus and Haemophilus influenzae. Latex agglutination and molecular serotyping were performed on samples. Antibiogram and whole genome sequencing were performed on pneumococcal isolates. RESULTS: Eight hundred eighty six patients were reported with suspected meningitis in the Brong-Ahafo region during the period of the outbreak. In the epicenter district, the prevalence was as high as 363 suspected cases per 100,000 people. Over 95 % of suspected cases occurred in non-infant children and adults, with a median age of 20 years. Bacterial meningitis was confirmed in just under a quarter of CSF specimens tested. Pneumococcus, meningococcus and Group B Streptococcus accounted for 77 %, 22 % and 1 % of confirmed cases respectively. The vast majority of serotyped pneumococci (80 %) belonged to serotype 1. Most of the pneumococcal isolates tested were susceptible to a broad range of antibiotics, with the exception of two pneumococcal serotype 1 strains that were resistant to both penicillin and trimethoprim-sulfamethoxazole. All sequenced pneumococcal serotype 1 strains belong to Sequence Type (ST) 303 in the hypervirulent ST217 clonal complex. CONCLUSION: The occurrence of a pneumococcal serotype 1 meningitis outbreak three years after the introduction of PCV13 is alarming and calls for strengthening of meningitis surveillance and a re-evaluation of the current vaccination programme in high risk countries

    Molecular epidemiology of pneumococci obtained from Gambian children aged 2–29 months with invasive pneumococcal disease during a trial of a 9-valent pneumococcal conjugate vaccine

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    BACKGROUND: The study describes the molecular epidemiology of Streptococcus pneumoniae causing invasive disease in Gambian children METHODS: One hundred and thirty-two S. pneumoniae isolates were recovered from children aged 2-29 months during the course of a pneumococcal conjugate vaccine trial conducted in The Gambia of which 131 were characterized by serotyping, antibiotic susceptibility, BOX-PCR and MLST. RESULTS: Twenty-nine different serotypes were identified; serotypes 14, 19A, 12F, 5, 23F, and 1 were common and accounted for 58.3% of all serotypes overall. MLST analysis showed 72 sequence types (STs) of which 46 are novel. eBURST analysis using the stringent 6/7 identical loci definition, grouped the isolates into 17 clonal complexes and 32 singletons. The population structure of the 8 serotype 1 isolates obtained from 4 vaccinated and 2 unvaccinated children were the same (ST 618) except that one (ST3336) of the isolates from an unvaccinated child had a novel ST which is a single locus variant of ST 618. CONCLUSION: We provide the first background data on the genetic structure of S. pneumoniae causing IPD prior to PC7V use in The Gambia. This data will be important for assessing the impact of PC7V in post-vaccine surveillance from The Gambia
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