323 research outputs found
The effect of varying levels of vehicle automation on drivers’ lane changing behaviour
Much of the Human Factors research into vehicle automation has focused on driver responses to critical scenarios where a crash might occur. However, there is less knowledge about the effects of vehicle automation on drivers’ behaviour during non-critical take-over situations, such as driver-initiated lane-changing or overtaking. The current driving simulator study, conducted as part of the EC-funded AdaptIVe project, addresses this issue. It uses a within-subjects design to compare drivers’ lane-changing behaviour in conventional manual driving, partially automated driving (PAD) and conditionally automated driving (CAD). In PAD, drivers were required to re-take control from an automated driving system in order to overtake a slow moving vehicle, while in CAD, the driver used the indicator lever to initiate a system-performed overtaking manoeuvre. Results showed that while drivers’ acceptance of both the PAD and CAD systems was high, they generally preferred CAD. A comparison of overtaking positions showed that drivers initiated overtaking manoeuvres slightly later in PAD than in manual driving or CAD. In addition, when compared to conventional driving, drivers had higher deviations in lane positioning and speed, along with higher lateral accelerations during lane changes following PAD. These results indicate that even in situations which are not time-critical, drivers’ vehicle control after automation is degraded compared to conventional driving
Central obesity and advanced liver stiffness in Hepatitis B: Result from golestan hepatitis B cohort study
Background: Chronic infection with the hepatitis B virus and obesity may both contribute synergistically to liver disease, although relatively few studies have investigated this hypothesis. Therefore, in this study, we evaluated the relationship between central obesity and the liver stiffness in the Golestan Hepatitis B cohort study (GHBCS). Methods: Our study included 304 chronic hepatitis B (CHB) patients enrolled from GHBCS. Liver stiffness measurement (LSM) and laboratory tests were performed after a follow-up of 4 years (2012). The hepatitis B viral load was measured at the baseline and follow-up using the real-time PCR method. Waist circumference ≥102 cm in men and ≥ 89 cm in women (central obesity) was considered to be abnormal. Advanced liver stiffness (ALS) was defined as LSM≥8 KPa. Statistical analysis was performed using SPSS-V17. Logistic regression was used to test predictors of advanced liver stiffness (LSM ≥ 8 KPa). Linear regression was used to test the predictive value of variables in ALT (as a continuous variable). P-value of less than 0.05 was considered statistically significant. Results: Among these CHB patients, 19 (7.4%) cases with a mean (±SD) age of 49.5 (±6.3) developed ALS after 4 years of follow-up. Multivariate analysis showed a significant predictive role of central obesity and viral load in ALS. Conclusions: Central obesity is related to the liver stiffness in chronic hepatitis B patients. © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved
Marked increase in the incidence rate of esophageal adenocarcinoma in a high-risk area for esophageal cancer
BACKGROUND: Esophageal cancer (EC) is the eighth common cancer worldwide. Esophageal squamous cell carcinoma (ESCC) and adenocarcinoma (EAD) are the most common histologic types of EC. Many recent reports showed an increasing trend in EAD and a decreasing trend in ESCC in many Western countries. Golestan Province in northeastern Iran has been known as a high-risk area for EC. The aim of this study was to describe the time trend of EAD in this area between 2000-2009. METHODS: Data on cancer cases were obtained from Golestan Population-based Cancer Registry. Analysis was done using Joinpoint software. To examine the incidence trends, the annual percent change was calculated. The possibilities of anatomic and histologic misclassification were considered by assessing the trend of ESCC and gastric adenocarcinoma. RESULTS: A total number of 1186 histologically-confirmed EC cases were recruited. The incidence rate of EAD showed a significant increasing trend. There was no significant trend in the incidence of ESCC during the study period. A significant increase in the incidence rate of gastric adenocarcinoma was observed during the period of 2000-2005, followed by a plateau during the period of 2005-2009. CONCLUSIONS: We found a significant increasing trend in the incidence rate of EAD. We find no evidence to support an alternative explanation including anatomic and histologic misclassification. So, the observed rise in the incidence of EAD seems to be real. Therefore, designing and implementation of control programs, including control of preventable risk factors of EAD, should be considered in this high- risk area
The impact of illicit drug use on Spontaneous Hepatitis C Clearance: Experience from a large cohort population study
Background and Aims: Acute hepatitis C infection usually ends in chronic infection, while in a minority of patients it is spontaneously cleared. The current population-based study is performed on a large cohort in Golestan province of Iran to examine the demographic correlates of Spontaneous Hepatitis C Clearance. Methods: Serum samples used in this study had been stored in biorepository of Golestan Cohort Study. These samples were evaluated for anti hepatitis C Virus by third generation Enzyme-linked immunosorbent assay (ELISA). Subjects who tested positive were then invited and tested by Recombinant Immunoblot Assay (RIBA) and Ribonucleic Acid Polymerase Chain Reaction test (PCR). If tested positive for RIBA, subjects were recalled and the two tests were re-done after 6 months. Those subjects who again tested positive for RIBA but negative for PCR were marked as cases of spontaneous clearance. Results: 49,338 serum samples were evaluated. The prevalence of Chronic Hepatitis C Virus (CHCV) infection based on PCR results was 0.31. Among those who had acquired hepatitis C, the rate of SC was 38. In multivariate analysis, illicit drug use both Injecting Use (OR = 3.271, 95 CI: 1.784-6.000, p-value<0.001) and Non-Injecting Use (OR = 1.901, 95 CI: 1.068-3.386, p-value = 0.029) were significant correlates of CHCV infection versus SC. Conclusions: Illicit drug use whether intravenous or non-intravenous is the only significant correlate of CHCV, for which several underlying mechanisms can be postulated including repeated contacts with hepatitis C antigen. © 2011 Poustchi et al
Sustained sensorimotor control as intermittent decisions about prediction errors: computational framework and application to ground vehicle steering
A conceptual and computational framework is proposed for modelling of human sensorimotor control and is exemplified for the sensorimotor task of steering a car. The framework emphasises control intermittency and extends on existing models by suggesting that the nervous system implements intermittent control using a combination of (1) motor primitives, (2) prediction of sensory outcomes of motor actions, and (3) evidence accumulation of prediction errors. It is shown that approximate but useful sensory predictions in the intermittent control context can be constructed without detailed forward models, as a superposition of simple prediction primitives, resembling neurobiologically observed corollary discharges. The proposed mathematical framework allows straightforward extension to intermittent behaviour from existing one-dimensional continuous models in the linear control and ecological psychology traditions. Empirical data from a driving simulator are used in model-fitting analyses to test some of the framework’s main theoretical predictions: it is shown that human steering control, in routine lane-keeping and in a demanding near-limit task, is better described as a sequence of discrete stepwise control adjustments, than as continuous control. Results on the possible roles of sensory prediction in control adjustment amplitudes, and of evidence accumulation mechanisms in control onset timing, show trends that match the theoretical predictions; these warrant further investigation. The results for the accumulation-based model align with other recent literature, in a possibly converging case against the type of threshold mechanisms that are often assumed in existing models of intermittent control
Were they in the loop during automated driving? Links between visual attention and crash potential
Background: A proposed advantage of vehicle automation is that it relieves drivers from the moment-to-moment demands of driving, to engage in other, non-driving related, tasks. However, it is important to gain an understanding of drivers’ capacity to resume manual control, should such a need arise. As automation removes vehicle control-based measures as a performance indicator, other metrics must be explored. Methods: This driving simulator study, conducted under the European Commission (EC) funded AdaptIVe project, assessed drivers’ gaze fixations during partially-automated (SAE Level 2) driving, on approach to critical and non-critical events. Using a between-participant design, 75 drivers experienced automation with one of five out-of-the-loop (OOTL) manipulations, which used different levels of screen visibility and secondary tasks to induce varying levels of engagement with the driving task: 1) no manipulation, 2) manipulation by light fog, 3) manipulation by heavy fog, 4) manipulation by heavy fog plus a visual task, 5) no manipulation plus an n-back task. Results: The OOTL manipulations influenced drivers’ first point of gaze fixation after they were asked to attend to an evolving event. Differences resolved within one second and visual attention allocation adapted with repeated events, yet crash outcome was not different between OOTL manipulation groups. Drivers who crashed in the first critical event showed an erratic pattern of eye fixations towards the road centre on approach to the event, while those who did not demonstrated a more stable pattern. Conclusions: Automated driving systems should be able to direct drivers’ attention to hazards no less than 6 seconds in advance of an adverse outcome
Polypill for prevention of cardiovascular disease in an Urban Iranian population with special focus on nonalcoholic steatohepatitis: A pragmatic randomized controlled trial within a cohort (PolyIran - Liver) – Study protocol
Background: Cardiovascular disease (CVD) is among the most common causes of mortality in all populations. Nonalcoholic steatohepatitis is a common finding in patients with CVD. Prevention of CVD in individual patients typically requires periodic clinical evaluation, as well as diagnosis and management of risk factors such as hypertension and hyperlipidemia. However, this is resource consuming and hard to implement, especially in developing countries. We designed a study to investigate the effects of a simpler strategy: a fixed-dose combination pill consisting of aspirin, valsartan, atorvastatin and hydrochlorthiazide (PolyPill) in an unselected group of persons aged over 50 years. Design: The PolyIran-Liver study was performed in Gonbad city as an open label pragmatic randomized controlled trial nested within the Golestan Cohort Study. We randomly selected 2,400 cohort study participants aged above 50 years, randomly assigned them to intervention or usual care and invited them to participate in an additional measurement study (if they met the eligibility criteria) to measure liver related outcomes. Those agreeing and randomized to the intervention arm were offered a daily single dose of PolyPill. We will follow participants for 5 years. The primary outcome is major cardiovascular events, secondary outcomes include all-cause mortality and liver related outcomes: liver stiffness and liver enzyme levels. Cardiovascular outcomes and mortality will be determined from the cohort study and liver-related outcomes in those consenting to follow up. Analysis will be by allocated group. Trial Status: Between October and December 2011, 1,320 intervention and 1,080 control participants were invited to participate in the additional measurement study. For all these participants, the major cardiovascular events will be determined using blind assessment of outcomes through the cohort study. In the intervention and control arms, 875 (66%) and 721 (67%) respectively, met the eligibility criteria and agreed to participate in the additional measurement study. Liver related outcomes will be measured in these participants. Of the 1,320 participants randomized to the intervention, 787 (60%) accepted the PolyPill. Conclusion: The PolyIran-liver urban study will provide us with important information on the effectiveness of PolyPill on major cardiovascular events, all-cause mortality and liver related outcomes. (ClinicalTrials.gov ID: NCT01245608). © 2015, Academy of Medical Sciences of I.R. Iran. All rights reserved
Reliability analysis of a newly developed questionnaire for quality control of follow-up visits in polyiran study
Background: The PolyIran study is a large-scale pragmatic cluster randomized controlled trial of fixed-dose combination therapy (Polypill) for prevention of cardiovascular diseases (CVD) in Iran. The PolyIran Quality Control Program (PIQCP) including a new questionnaire was developed to assess the quality of data collection during follow-up visits. The aim of this study was to assess the inter-rater reliability of PIQCP questionnaire. Methods: The study was conducted in 26 (11%) randomly selected clusters (from a total of 236 PolyIran clusters). All participants within these 26 clusters were enrolled. The quality scores were measured according to the PIQCP guidelines by two independent raters. The intraclass correlation coefficients (ICC) were measured. In addition, the quality scores were categorized into good (370%) and poor (<70%). The kappa coefficient was used to assess inter-rater agreement for this categorical quality scores. Results: A total number of 945 PolyIran participants were enrolled of which, 501 (53%) were from intervention arm. In 934 participants (98.8%), the quality score could be successfully identified by both raters. The ICC (95%CI) ofthe overall quality scores was 0.985 (0.983-0.987). It was 0.976 (0.972-0.980) and 0.988 (0.986-0.990) in intervention and control arms, respectively. We found excellent agreement between the two raters in identifying participants with good and poor quality scores (kappa = 0.988, P < 0.001). The kappa values were 0.972 (P < 0.001) and 1.000 (P < 0.001) in intervention and control arms, respectively. Discussion: Our results suggested that the PIQCP questionnaire is a reliable tool for assessing quality of data collection in PolyIran follow-up visits. Using this measure will help us in efficient monitoring of the PolyIran follow-ups and may ensure high quality data. © 2016, Academy of Medical Sciences of I.R. Iran. All rights reserved
Prognostic factors for esophageal squamous cell Carcinoma-A Population-Based study in Golestan province, Iran, a high incidence area
Golestan Province in northern Iran is an area with a high incidence of esophageal squamous cell carcinoma (ESCC). We aimed to investigate prognostic factors for ESCC and survival of cases in Golestan, on which little data were available. We followed-up 426 ESCC cases participating in a population-based case-control study. Data were analyzed using the Kaplan-Meier method and the Cox proportional hazard models. Median survival was 7 months. Age at diagnosis was inversely associated with survival, but the association was disappeared with adjustment for treatment. Residing in urban areas (hazard ratio, HR = 0.70; 95 CI 0.54-0.90) and being of non-Turkmen ethnic groups (HR = 0.76; 95 CI 0.61-0.96) were associated with better prognosis. In contrast to other types of tobacco use, nass (a smokeless tobacco product) chewing was associated with a slightly poorer prognosis even in models adjusted for other factors including stage of disease and treatment (HR = 1.38; 95 CI 0.99-1.92). Opium use was associated with poorer prognosis in crude analyses but not in adjusted models. Almost all of potentially curative treatments were associated with longer survival. Prognosis of ESCC in Golestan is very poor. Easier access to treatment facilities may improve the prognosis of ESCC in Golestan. The observed association between nass chewing and poorer prognosis needs further investigations; this association may suggest a possible role for ingestion of nass constituents in prognosis of ESCC. © 2011 Aghcheli et al
When Should the Chicken Cross the Road? - Game Theory for Autonomous Vehicle - Human Interactions
Autonomous vehicle localization, mapping and planning in un-reactive environments are well-understood, but the human factors of complex interactions with other road users are not yet developed. This study presents an initial model for negotiation between an autonomous vehicle and another vehicle at an unsigned intersections or (equivalently) with a pedestrian at an unsigned road-crossing (jaywalking), using discrete sequential game theory. The model is intended as a basic framework for more realistic and data-driven future extensions. The model shows that when only vehicle position is used to signal intent, the optimal behaviors for both agents must include a non-zero probability of allowing a collision to occur. This suggests extensions to reduce this probability in future, such as other forms of signaling and control. Unlike most Game Theory applications in Economics, active vehicle control requires real-time selection from multiple equilibria with no history, and we present and argue for a novel solution concept, meta-strategy convergence, suited to this task
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