This study investigates relationships between congestion and travel time performance metrics and crashes on road segments. The study focuses on work zone routes in Iowa, utilizing 2021 commercially-available probe veh...This study investigates relationships between congestion and travel time performance metrics and crashes on road segments. The study focuses on work zone routes in Iowa, utilizing 2021 commercially-available probe vehicle data and crash data. Travel time performance metrics were derived from the probe vehicle data, and crash counts were obtained from the crash data. Additional variables included road characteristics (traffic volume, road type, segment length) and a categorical variable for the presence of a work zone. A mixed effect linear regression model was employed to identify relationships between road segment crash counts and the selected performance metrics. This was accomplished for two sets of models that include congestion performance measures at different defining threshold values, along with travel time performance measures. The study results indicate that the congestion indicators, certain travel time performance measures, and traffic counts were statistically significant and positively correlated with crash counts. Indicator variables for rural interstate locations and non-active work zones have a stronger influence on crash count than those for municipal interstate locations and active work zones. These findings can inform decision-makers on work zone safety strategies and crash mitigation planning, especially in high traffic volume areas prone to congestion and queues.展开更多
S:Understanding how surface energy fluxes respond to environmental variables and how their components vary on daily and seasonal temporal scales are critical for understanding the ecological process of wetland ecosyst...S:Understanding how surface energy fluxes respond to environmental variables and how their components vary on daily and seasonal temporal scales are critical for understanding the ecological process of wetland ecosystem. In view of the fact that studies on surface energy flux over mire in China have been very limited, we have initiated a long-term latent and sensible heat flux (two main components of the surface energy balance) observation over mire in the Sanjiang Plain from June to October in 2004 with the eddy covariance technique. Results showed that the latent and sensible heat flux had large seasonal and diurnal variation during the period of measurement. Generally, latent heat flux between the mire wetland and the atmosphere reached the maximum value in June and then gradually decreased from June to October, whose daily mean fluxes were 9.83,8.00,7.33, 4.82 and 2.04 MJ/(m^2·d), respectively. By comparison, sensible heat flux changed unnoticeably with season change from June to October, which were 1.47,0.88,1.75, 1.61,1.33 MJ/(m^2·d) respectively. The diurnal variation of both latent and sensible heat flux varied noticeably within a day. After the sunrise, the latent and sensible heat flux increased and reached the maximum at noon (11:00-13:00). Then they decreased gradually and reached the minimum value during the nighttime. The patterns of temporal variation in latent and sensible heat flux were significantly controlled by environmental factors. The latent heat flux was linearly dependent on net radiation and increased with increasing vapour pressure deficit until the vapour pressure deficit surpassed 11 hPa. Wind speed effect on latent heat flux was more complicated and, in general, showed a positive correlation between them in daytime. The sensible heat flux was controlled mainly by air temperature difference between the land surface and the overlying air. However, when the temperature difference was larger than 0.3 ℃, it had no effect on the sensible heat flux. The study showed up the temporal variation of latent and sensible heat flux and how the environmental factors affected them.展开更多
目的比较首发缺陷型精神分裂症(first-episode deficit subtype of schizophrenia,FDS)患者和首发非缺陷型精神分裂症(first-episode nondeficit subtype of schizophrenia,FNDS)患者精神病性症状和神经认知功能的差异。方法于2021年1—...目的比较首发缺陷型精神分裂症(first-episode deficit subtype of schizophrenia,FDS)患者和首发非缺陷型精神分裂症(first-episode nondeficit subtype of schizophrenia,FNDS)患者精神病性症状和神经认知功能的差异。方法于2021年1—9月在四川大学华西医院心理卫生中心门诊或病房招募首发未治疗的精神分裂症患者,通过缺陷型精神分裂症诊断量表(schedule for the deficit syndrome,SDS)将患者分为缺陷型(FDS组,n=44)和非缺陷型(FNDS组,n=44)。同时在社区招募44名健康对照(healthy controls,HC组)。采用阳性和阴性症状量表(positive and negative syndrome scale,PANSS)评估患者精神病性症状,采用韦氏成人智力测试(Wechsler adult intelligence scale,WAIS-RC)、连线测验和逻辑记忆测试评估所有被试的智商和神经认知功能。运用SPSS 22.0软件进行统计分析,采用独立样本t检验,单因素方差分析比较符合正态分布的变量,采用Mann-Whitney秩和检验和Kruskal-Wallis秩和检验比较不符合正态分布的变量。结果(1)FDS组和FNDS组的精神病性症状存在明显差异:与FNDS组相比,FDS组的PANSS总分[(95.95±16.82)分比(88.39±16.29)分]、阴性症状分[(27.57±7.52)分比(16.57±5.76)分]和反应缺乏因子分[(13.43±3.82)分比(7.00(5.00,9.00)分]更高(均P<0.05),而阳性症状分[(21.95±6.88)分比(25.41±6.07)分]、激活性因子分[8.00(5.00,9.00)分比(9.27±3.47)分]、抑郁因子分[5.50(4.00,9.00)分比(8.00(6.00,12.00)分]和补充项目分[(13.60±4.17)分比(17.30±5.39)]更低(均P<0.05)。(2)FDS组和FDNS组的神经认知功能存在差异,且比HC组更差:FDS组的空间记忆分[木块图测试:(23.70±11.05)分比(31.72±11.49)分]和信息处理速度分[数字符号测试:(38.38±15.85)分比(47.97±14.99)分]显著低于FNDS组(均P<0.05);FDS组和FNDS组的智商、信息处理速度分和空间记忆分等指标均低于HC组(均P<0.05)。结论首发缺陷型精神分裂症相较于非缺陷型,具有更严重的阴性症状和反应缺乏症状,同时信息处理速度和空间记忆明显损伤,提示信息处理速度和空间记忆可能是早期区分缺陷型精神分裂症重要的分型指标。展开更多
文摘This study investigates relationships between congestion and travel time performance metrics and crashes on road segments. The study focuses on work zone routes in Iowa, utilizing 2021 commercially-available probe vehicle data and crash data. Travel time performance metrics were derived from the probe vehicle data, and crash counts were obtained from the crash data. Additional variables included road characteristics (traffic volume, road type, segment length) and a categorical variable for the presence of a work zone. A mixed effect linear regression model was employed to identify relationships between road segment crash counts and the selected performance metrics. This was accomplished for two sets of models that include congestion performance measures at different defining threshold values, along with travel time performance measures. The study results indicate that the congestion indicators, certain travel time performance measures, and traffic counts were statistically significant and positively correlated with crash counts. Indicator variables for rural interstate locations and non-active work zones have a stronger influence on crash count than those for municipal interstate locations and active work zones. These findings can inform decision-makers on work zone safety strategies and crash mitigation planning, especially in high traffic volume areas prone to congestion and queues.
文摘S:Understanding how surface energy fluxes respond to environmental variables and how their components vary on daily and seasonal temporal scales are critical for understanding the ecological process of wetland ecosystem. In view of the fact that studies on surface energy flux over mire in China have been very limited, we have initiated a long-term latent and sensible heat flux (two main components of the surface energy balance) observation over mire in the Sanjiang Plain from June to October in 2004 with the eddy covariance technique. Results showed that the latent and sensible heat flux had large seasonal and diurnal variation during the period of measurement. Generally, latent heat flux between the mire wetland and the atmosphere reached the maximum value in June and then gradually decreased from June to October, whose daily mean fluxes were 9.83,8.00,7.33, 4.82 and 2.04 MJ/(m^2·d), respectively. By comparison, sensible heat flux changed unnoticeably with season change from June to October, which were 1.47,0.88,1.75, 1.61,1.33 MJ/(m^2·d) respectively. The diurnal variation of both latent and sensible heat flux varied noticeably within a day. After the sunrise, the latent and sensible heat flux increased and reached the maximum at noon (11:00-13:00). Then they decreased gradually and reached the minimum value during the nighttime. The patterns of temporal variation in latent and sensible heat flux were significantly controlled by environmental factors. The latent heat flux was linearly dependent on net radiation and increased with increasing vapour pressure deficit until the vapour pressure deficit surpassed 11 hPa. Wind speed effect on latent heat flux was more complicated and, in general, showed a positive correlation between them in daytime. The sensible heat flux was controlled mainly by air temperature difference between the land surface and the overlying air. However, when the temperature difference was larger than 0.3 ℃, it had no effect on the sensible heat flux. The study showed up the temporal variation of latent and sensible heat flux and how the environmental factors affected them.
文摘目的比较首发缺陷型精神分裂症(first-episode deficit subtype of schizophrenia,FDS)患者和首发非缺陷型精神分裂症(first-episode nondeficit subtype of schizophrenia,FNDS)患者精神病性症状和神经认知功能的差异。方法于2021年1—9月在四川大学华西医院心理卫生中心门诊或病房招募首发未治疗的精神分裂症患者,通过缺陷型精神分裂症诊断量表(schedule for the deficit syndrome,SDS)将患者分为缺陷型(FDS组,n=44)和非缺陷型(FNDS组,n=44)。同时在社区招募44名健康对照(healthy controls,HC组)。采用阳性和阴性症状量表(positive and negative syndrome scale,PANSS)评估患者精神病性症状,采用韦氏成人智力测试(Wechsler adult intelligence scale,WAIS-RC)、连线测验和逻辑记忆测试评估所有被试的智商和神经认知功能。运用SPSS 22.0软件进行统计分析,采用独立样本t检验,单因素方差分析比较符合正态分布的变量,采用Mann-Whitney秩和检验和Kruskal-Wallis秩和检验比较不符合正态分布的变量。结果(1)FDS组和FNDS组的精神病性症状存在明显差异:与FNDS组相比,FDS组的PANSS总分[(95.95±16.82)分比(88.39±16.29)分]、阴性症状分[(27.57±7.52)分比(16.57±5.76)分]和反应缺乏因子分[(13.43±3.82)分比(7.00(5.00,9.00)分]更高(均P<0.05),而阳性症状分[(21.95±6.88)分比(25.41±6.07)分]、激活性因子分[8.00(5.00,9.00)分比(9.27±3.47)分]、抑郁因子分[5.50(4.00,9.00)分比(8.00(6.00,12.00)分]和补充项目分[(13.60±4.17)分比(17.30±5.39)]更低(均P<0.05)。(2)FDS组和FDNS组的神经认知功能存在差异,且比HC组更差:FDS组的空间记忆分[木块图测试:(23.70±11.05)分比(31.72±11.49)分]和信息处理速度分[数字符号测试:(38.38±15.85)分比(47.97±14.99)分]显著低于FNDS组(均P<0.05);FDS组和FNDS组的智商、信息处理速度分和空间记忆分等指标均低于HC组(均P<0.05)。结论首发缺陷型精神分裂症相较于非缺陷型,具有更严重的阴性症状和反应缺乏症状,同时信息处理速度和空间记忆明显损伤,提示信息处理速度和空间记忆可能是早期区分缺陷型精神分裂症重要的分型指标。
