| 1. |
- Morokuma, Tomoki, et al.
(författare)
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OISTER optical and near-infrared monitoring observations of peculiar radio-loud active galactic nucleus SDSSJ110006.07+442144.3
- 2017
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Ingår i: Nippon Tenmon Gakkai obun kenkyu hokoku. - : Oxford University Press (OUP). - 0004-6264. ; 69:5
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Tidskriftsartikel (refereegranskat)abstract
- We present monitoring campaign observations at optical and near-infrared (NIR) wavelengths for a radio-loud active galactic nucleus (AGN) at z = 0.840, SDSSJ110006.07+442144.3 (hereafter, J1100+4421), which was identified during a flare phase in late 2014 February. The campaigns consist of three intensive observing runs from the discovery to 2015 March, mostly within the scheme of the OISTER collaboration. Optical-NIR light curves and simultaneous spectral energy distributions (SEDs) are obtained. Our measurements show the strongest brightening in 2015 March. We found that the optical-NIR SEDs of J1100+4421 show an almost steady shape despite the large and rapid intranight variability. This constant SED shape is confirmed to extend to similar to 5 mu m in the observed frame using the archival WISE data. Given the lack of absorption lines and the steep power-law spectrum of alpha(upsilon) similar to -1.4, where f(v) proportional to v(alpha upsilon), synchrotron radiation by a relativistic jet with no or small contributions from the host galaxy and the accretion disk seemsmost plausible as an optical-NIR emission mechanism. The steep optical-NIR spectral shape and the large amplitude of variability are consistent with this object being a low.peak jet-dominated AGN. In addition, sub-arcsecond resolution optical imaging data taken with Subaru Hyper Suprime-Cam does not show a clear extended component and the spatial scales are significantly smaller than the large extensions detected at radio wavelengths. The optical spectrum of a possible faint companion galaxy does not show any emission lines at the same redshift, and hence a merging hypothesis for this AGN-related activity is not supported by our observations.
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| 2. |
- Bianchi Piccinini, Giulio, 1982, et al.
(författare)
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Influence of oncoming traffic on drivers’ decision to overtake cyclists
- 2017
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Ingår i: Proceedings of the 2017 Road Safety & Simulation International Conference.
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Konferensbidrag (refereegranskat)abstract
- Active transportation - such as cycling - can provide health benefits to the population. However, cycling safety remains a major threat to favour the use of bicycles and, for this reason, more efforts are needed to reduce the number of crashes involving cyclists. One scenario which deserves special attention is driver’s overtaking of cyclists since it has an increased likelihood to lead to severe injuries. The decision process for the overtaking manoeuvre is highly influenced by driver’s subjective feeling of risk and the presented driving simulator study aimed to understand how drivers overtake cyclists in the presence of oncoming traffic. Forty-two Japanese participants were recruited to drive on a 16 km long route and were requested to perform eight overtaking manoeuvres of cyclists, with the oncoming vehicle at different values of nominal time to collision in each overtaking manoeuvre. The results showed that the nominal time to collision against the oncoming vehicle had a significant effect on the overtaking strategy (accelerative vs. flying) and on the minimum safety margins towards the bicycle chosen by the overtaking driver. Besides, analysing the data by overtaking strategy, a decrease in minimum safety margins towards the bicycle was found for drivers who opted for a flying overtaking strategy: the drivers who completed the overtaking manoeuvre without letting pass the oncoming traffic reduced their lateral distance to the bicycle when the nominal time to collision decreased. Finally, the current research showed that minimum lateral safety margins were larger in accelerative manoeuvres compared to flying manoeuvres in the most critical overtaking manoeuvre. Overall, the research show that the comfort – and, possibly, the safety – of cyclists might be compromised in overtaking manoeuvres with oncoming traffic. Also, the study provides some implications for the design of active safety systems and automated driving.
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| 3. |
- Bianchi Piccinini, Giulio, 1982, et al.
(författare)
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Influence of oncoming traffic on drivers’ overtaking of cyclists
- 2018
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - : Elsevier BV. - 1369-8478. ; 59:Part A, s. 378-388
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Tidskriftsartikel (refereegranskat)abstract
- Active transportation - such as cycling - can provide health benefits to the population. However, cycling safety remains a major threat to favour the use of bicycles and, for this reason, more efforts are needed to reduce the number of crashes involving cyclists. One crash scenario which deserves special attention is driver’s overtaking of cyclists since it has an increased likelihood to lead to severe injuries. During the overtaking manoeuvre, the monitoring of subjective risk can influence the decision-making process and lead to different outcomes. In this context, the present driving simulator study aims to investigate how the time to collision between oncoming traffic and subject vehicle affected the overtaking strategy, and the minimum safety margins towards the overtaken cyclist. The results show that a decrease in time to collision against the oncoming vehicle significantly affects the drivers’ overtaking strategy (accelerative vs. flying), inducing more drivers to choose an accelerative overtaking manoeuvre. The decrease in time to collision also produces a decrease in minimum safety margins to the cyclists for drivers who opt for a flying overtaking strategy. Finally, the current research shows that the minimum lateral safety margins were smaller and the mean speed higher in flying manoeuvres compared to accelerative manoeuvres. Overall, the combination of lower safety margins and higher mean speeds in flying overtaking manoeuvres seems to pose a risk for cyclists’ safety. The findings of the study provide some implications for the design of automated driving.
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| 4. |
- Farah, Haneen, et al.
(författare)
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Drivers’ Decision Making of Overtaking Strategies of Cyclists on Rural Roads–A Driving Simulator Experiment
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Cyclists’ involvement in road crashes has not been improving with the same magnitude as other modes of transport. Especially, the interactions between cyclists and motorized traffic can end up with the most severe types of crashes. To improve the safety of these interactions, a thorough understanding of road users’ decisions and behaviours is first needed. In this study, the authors focus on drivers’ overtaking manoeuvres of cyclists on rural roads. The main objective of this study is to develop a model that can predict drivers’ decisions whether to perform a flying or an accelerative overtaking manoeuvre when approaching a cyclist in the presence of oncoming traffic. A driving simulator study was designed to collect trajectory data of the overtaking vehicle, cyclist, and oncoming traffic. Drivers’ characteristics data was collected using surveys. In total, 37 drivers participated, each of them performing 7 overtaking manoeuvres. Out of 259 overtaking manoeuvres, 168 were flying and 91 were accelerative. Two binary logistic regression models were developed and estimated. In the two models, the time-to-collision and the driver’s speed significantly affect the decision on the overtaking manoeuvre type. In the first model, the correlations among the observations of the same driver were captured through the drivers’ characteristics. In the second model, these correlations were captured through a driver specific error term. The overall performance is 87.7% and 94.9% for the first and second models, respectively. In the paper the authors discuss the usability of each model for policy making, system design, and system evaluation.
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| 5. |
- Farah, Haneen, et al.
(författare)
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Modelling overtaking strategy and lateral distance in car-to-cyclist overtaking on rural roads: A driving simulator experiment
- 2019
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Ingår i: Transportation Research Part F: Traffic Psychology and Behaviour. - : Elsevier BV. - 1369-8478. ; 63, s. 226-239
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Tidskriftsartikel (refereegranskat)abstract
- The involvement of cyclists in road crashes has not been decreasing with the same magnitude as the involvement of other road users. In particular, the interactions between cyclists and motorized traffic can lead to high-severity crashes. To improve the safety of these interactions, a thorough understanding of road user behaviour is first needed. In this study, we focused on drivers overtaking cyclists on rural roads. The two main objectives of this study were to develop models that predicted: (a) drivers’ decisions to perform either a flying or an accelerative overtaking manoeuvre in the presence of oncoming traffic, and (b) the lateral comfort distance that drivers maintain from cyclists during the overtaking. A driving simulator study was designed to assess driver decision-making during the overtaking. The 37 drivers who participated in the study each performed seven overtaking manoeuvres with oncoming traffic. Out of the 259 overtaking manoeuvres, 168 were flying and 91 were accelerative. Binary logistic-regression models with mixed effects predicted the type of overtaking strategy (flying or accelerative). Driving speeds were found to significantly affect the strategy. The overall performance of the models predicting the strategy was 85–90%. Models were also developed for predicting the lateral comfort distance. The results show that the lateral comfort distance is mostly affected by the longitudinal distance between the subject vehicle and the oncoming vehicle, the longitudinal distance between the subject vehicle and the cyclist, and the presence of an oncoming vehicle—as well as by the drivers’ characteristics (sensation seeking in flying overtaking manoeuvres and ordinary violations in accelerative manoeuvres). The root mean square error, which was used to assess the performance of the models, ranged from 0.56 to 0.62. In conclusion, the models predicting the overtaking strategy performed reasonably well, while the models predicting lateral distance did not provide accurate predictions. The models predicting overtaking strategy may support (1) the development and evaluation of active safety systems, (2) the design of automated driving, and (3) policy making.
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| 6. |
- Hawlader, Mohammad D H, et al.
(författare)
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Ascaris lumbricoids Infection as a Risk Factor for Asthma and Atopy in Rural Bangladeshi Children.
- 2014
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Ingår i: Tropical Medicine and Health. - : Japanese Society of Tropical Medicine. - 1348-8945 .- 1349-4147. ; 42:2, s. 77-85
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Tidskriftsartikel (refereegranskat)abstract
- Controversy persists as to whether helminth infections cause or protect against asthma and atopy. The aim of this study was to investigate the effects of helminth infection on asthma and atopy among Bangladeshi children. A total of 912 children aged 4.5 years (mean = 54.4, range = 53.5-60.8 months) participated in a cross-sectional study nested into a randomized controlled trial in Bangladesh. Ever-asthma, ever-wheezing and current wheezing were identified using the International Study of Asthma and Allergies in Childhood questionnaire. Current helminth infection was defined by the presence of helminth eggs in stools, measured by routine microscopic examination. Repeated Ascaris infection was defined by the presence of anti-Ascaris IgE ≥ 0.70 UA/ml in serum measured by the CAP-FEIA method. Atopy was defined by specific IgE to house dust mite (anti-DP IgE) ≥ 0.70 UA/ml measured by the CAP-FEIA method and/or positive skin prick test (≥ 5 mm). Anti-Ascaris IgE was significantly associated with ever asthma (odds ratio (OR) = 1.86, 95% CI: 1.14-3.04, highest vs. lowest quartile; P for trend 0.016). Anti-Ascaris IgE was also significantly associated with positive anti-DP IgE (OR = 9.89, 95% CI: 6.52-15.00, highest vs. lowest; P for trend < 0.001) and positive skin prick test (OR = 1.69, 95% CI: 1.01-2.81, highest vs. lowest, P for trend 0.076). These findings suggest that repeated Ascaris infection is a risk factor for asthma and atopy in rural Bangladeshi children. Further analysis is required to examine the mechanism of developing asthma and atopy in relation to helminth infection.
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| 7. |
- Konishi, Mihoko, et al.
(författare)
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A substellar companion to Pleiades HII 3441
- 2016
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 68:6
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Tidskriftsartikel (refereegranskat)abstract
- We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0.'' 49 +/- 0.'' 02 (66 +/- 2 au) and a mass of 68 +/- 5 M-J based on three observations in the J-, H-, and K-s-bands. The spectral type is estimated to be M7 (similar to 2700 K), and thus no methane absorption is detected in the H band. Our Pleiades observations result in the detection of two substellar companions including one previously reported among 20 observed Pleiades stars, and indicate that the fraction of substellar companions in the Pleiades is about 10.0(-8.8)(+26.1)%. This is consistent with multiplicity studies of both the Pleiades stars and other open clusters.
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| 8. |
- Ryu, Tsuguru, et al.
(författare)
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HIGH-CONTRAST IMAGING OF INTERMEDIATE-MASS GIANTS WITH LONG-TERM RADIAL VELOCITY TRENDS
- 2016
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 825:2
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Tidskriftsartikel (refereegranskat)abstract
- A radial velocity (RV) survey for intermediate-mass giants has been in operation for over a decade at Okayama Astrophysical Observatory (OAO). The OAO survey has revealed that some giants show long-term linear RV accelerations (RV trends), indicating the presence of outer companions. Direct-imaging observations can help clarify what objects generate these RV trends. We present the results of high-contrast imaging observations of six intermediate-mass giants with long-term RV trends using the Subaru Telescope and HiCIAO camera. We detected co-moving companions to gamma Hya B (0.61(-0.14)(+0.12)M(circle dot)), HD 5608 B (0.10 +/- 0.01M(circle dot)), and HD 109272 B (0.28 +/- 0.06M(circle dot)). For the remaining targets (iota Dra, 18 Del, and HD 14067), we exclude companions more massive than 30-60 M-Jup at projected separations of 1 ''-7 ''. We examine whether these directly imaged companions or unidentified long-period companions can account for the RV trends observed around the six giants. We find that the Kozai mechanism can explain the high eccentricity of the inner planets iota Dra b, HD 5608 b, and HD 14067 b.
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