88 research outputs found

    Multifunctional Adaptive NS1 Mutations Are Selected upon Human Influenza Virus Evolution in the Mouse

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    The role of the NS1 protein in modulating influenza A virulence and host range was assessed by adapting A/Hong Kong/1/1968 (H3N2) (HK-wt) to increased virulence in the mouse. Sequencing the NS genome segment of mouse-adapted variants revealed 11 mutations in the NS1 gene and 4 in the overlapping NEP gene. Using the HK-wt virus and reverse genetics to incorporate mutant NS gene segments, we demonstrated that all NS1 mutations were adaptive and enhanced virus replication (up to 100 fold) in mouse cells and/or lungs. All but one NS1 mutant was associated with increased virulence measured by survival and weight loss in the mouse. Ten of twelve NS1 mutants significantly enhanced IFN-Ξ² antagonism to reduce the level of IFN Ξ² production relative to HK-wt in infected mouse lungs at 1 day post infection, where 9 mutants induced viral yields in the lung that were equivalent to or significantly greater than HK-wt (up to 16 fold increase). Eight of 12 NS1 mutants had reduced or lost the ability to bind the 30 kDa cleavage and polyadenylation specificity factor (CPSF30) thus demonstrating a lack of correlation with reduced IFN Ξ² production. Mutant NS1 genes resulted in increased viral mRNA transcription (10 of 12 mutants), and protein production (6 of 12 mutants) in mouse cells. Increased transcription activity was demonstrated in the influenza mini-genome assay for 7 of 11 NS1 mutants. Although we have shown gain-of-function properties for all mutant NS genes, the contribution of the NEP mutations to phenotypic changes remains to be assessed. This study demonstrates that NS1 is a multifunctional virulence factor subject to adaptive evolution

    Using standardized patients to evaluate hospital-based intervention outcomes.

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    BackgroundThe standardized patient approach has proved to be an effective training tool for medical educators. This article explains the process of employing standardized patients in an HIV stigma reduction intervention in healthcare settings in China.MethodsThe study was conducted in 40 hospitals in two provinces of China. One year after the stigma reduction intervention, standardized patients made unannounced visits to participating hospitals, randomly approached service providers on duty and presented symptoms related to HIV and disclosed HIV-positive test results. After each visit, the standardized patients evaluated their providers' attitudes and behaviours using a structured checklist. Standardized patients also took open-ended observation notes about their experience and the evaluation process.ResultsSeven standardized patients conducted a total of 217 assessments (108 from 20 hospitals in the intervention condition; 109 from 20 hospitals in the control condition). Based on a comparative analysis, the intervention hospitals received a better rating than the control hospitals in terms of general impression and universal precaution compliance as well as a lower score on stigmatizing attitudes and behaviours toward the standardized patients.ConclusionStandardized patients are a useful supplement to traditional self-report assessments, particularly for measuring intervention outcomes that are sensitive or prone to social desirability

    Nonlinear Min-Cost-Pursued Route-Swapping Dynamic System

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    This study proposes a nonlinear min-cost-pursued swapping dynamic (NMSD) system to model the evolution of selfish routing games on traffic network where travelers only swap from previous costly routes to the least costly ones. NMSD is a rational behavior adjustment process with stationary link flow pattern being the Wardrop user equilibrium. NMSD is able to prevent two behavioral deficiencies suffered by the existing min-cost-oriented models and keep solution invariance. NMSD relaxes the homogeneous user assumption, and the continuous-time NMSD (CNMSD) and discrete-time NMSD (DNMSD) share the same revision protocol. Moreover, CNMSD is Lyapunov-stable. Two numerical examples are conducted. The first one is designed to characterize the NMSD-conducted network traffic evolution and test the stability of day-to-day NMSD. The second one aims to explore the impacts of network scale on the stability of route-swaps conducted by pairwise and min-cost-pursed swapping behaviors

    Potential travel cost saving in urban public-transport networks using smartphone guidance

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    <div><p>Public transport (PT) is a key element in most major cities around the world. With the development of smartphones, available journey planning information is becoming an integral part of the PT system. Each traveler has specific preferences when undertaking a trip, and these preferences can also be reflected on the smartphone. This paper considers transit assignment in urban public-transport networks in which the passengers receive smartphone-based information containing elements that might influence the travel decisions in relation to line loads, as well as passenger benefits, and the paper discusses the transition from the current widespread choosing approach to a personalized decision-making approach based on smartphone information. The approach associated with smartphone guidance that considers passengers’ preference on travel time, waiting time and transfer is proposed in the process of obtaining his/her preferred route from the potential travel routes generated by the Deep First Search (DFS) method. Two other approaches, based on the scenarios reflecting reality, include passengers with access to no real time information, and passengers that only have access to the arrival time at the platform are used as comparisons. For illustration, the same network proposed by Spiess and Florian is utilized on the experiments in an agent-based model. Two experiments are conducted respectively according to whether each passenger’s choosing method is consistent. As expected, the results in the first experiment showed that the travel for consistent passengers with smartphone guidance was clearly shorter and that it can reduce travel time exceeding 15% and weighted cost exceeding 20%, and the average saved time approximated 3.88 minutes per passenger. The second experiment presented that travel cost, as well as cost savings, gradually decreased by employing smartphone guidance, and the maximum cost savings accounted for 14.2% of the total weighted cost.</p></div

    Synchronizing Public Transport Transfers by Using Intervehicle Communication Scheme Case Study

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    Synchronized transfers in public transport (PT) networks play an important role in reducing transfer walking time, increasing PT network connectivity, and improving PT reliability and the attractiveness of the PT service. However, because of the dynamic, stochastic, and uncertain nature of traffic, planned synchronized PT transfers do not always materialize. Missed connections frustrate the PT passengers and reduce potential new users. This research proposed an intervehicle communication (IVC)-based scheme to optimize the synchronization of planned transfers in PT networks. A semidecentralized control strategy was developed for the IVC systems to make the optimization a parallel process. Two operational tactics, changing vehicle speed and holding vehicles at transfer points, were used in the optimization with real-time vehicle speed and location information. A distance-based dynamic speed-adjustment model was developed for updating vehicle running speed under the fixed single-point encounter scenario and flexible road-segment encounter scenario. The impact of the proposed IVC scheme on the total number of direct transfers and the total passenger travel time (TPTT) was investigated with a case study of a PT network from Beijing. Results showed that by applying the proposed methodology, the number of direct transfers was considerably increased by 1,100%, and the TPTT was significantly reduced by 13.2%

    CBVC-B: A System for Synchronizing Public-transport Transfers Using Vehicle-to-Vehicle Communication

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    This work proposes a communication-based vehicle control system for buses (CBVC-B) to synchronize passenger transfers in public-transport (PT) networks. The CBCV-B, using vehicle-to-vehicle communication, enables PT drivers to share their vehicle location, speed, direction, and passenger information with their peers within the same communication group. The main purpose of the CBVC-B is to increase the actual occurrence of planned direct-passenger transfers by the use of certain dynamic control tactics in real-time operation. A detail description of the CBVC-B is illustrated in this work including its main components and main features. The sequential decision-making process of the real-time deployment of operational control tactics in the CBVC-B is formulated as a finite-horizon Markov decision process model. The potential benefits of the proposed CBVC-B are also discussed from the perspectives of both the PT users and the PT operator. It is formulated as a bi-objective optimization problem. The Pareto optimal solutions can be displayed for the PT operators so as to serve as a basis for their decision-making process when selecting operational control tactics
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