Analysis of behavioral changes of zebrafish (Danio rerio) in response to formaldehyde using Self-organizing map and a hidden Markov model

Two computational methods were applied to classification of movement patterns of zebrafish (Danio rerio) to elucidate Markov processes in behavioral changes before and after treatment of formaldehyde (0.1 mg/L) in semi-natural conditions. The complex data of the movement tracks were initially classified by the Self-organizing map (SOM) to present different behavioral states of test individuals. Transition probabilities between behavioral states were further evaluated to fit Markov processes by using the hidden Markov model (HMM). Emission transition probability was also obtained from the observed variables (i.e., speed) for training with the HMM. Experimental transition and emission probability matrices were successfully estimated with the HMM for recognizing sequences of behavioral states with accuracy rates in acceptable ranges at central and boundary zones before (77.3-81.2%) and after (70.1-76.5%) treatment. A heuristic algorithm and a Markov model were efficiently combined to analyze movement patterns and could be a means of in situ behavioral monitoring tool.     

From the outside in: The negative spillover effects of boundary spanners' relations with members of other organizations

Contrary to much boundary spanning research, we examined the negative consequences of boundary spanning contact in multi‐organizational contexts. Results from a sample of 833 Dutch peacekeepers show that employees' boundary spanning contact with members of other organizations was associated with reports of negative relationships with external parties (e.g., work‐specific problems, culture‐specific problems). These negative relationships also had a spillover effect such that they mediated the effect of boundary spanning contact on boundary spanners' negative attitudes toward their own jobs and organization (e.g., job attractiveness and confidence in the organization). Copyright © 2010 John Wiley & Sons, Ltd.     

气溶胶辐射效应对气象和环境影响的观测与模拟研究

选取2015年和2019年不同代表年份,结合外场观测和数值模拟,分析了天津地区不同季节不同天气(晴天、多云、霾)下,气溶胶辐射效应对整层大气透过率和地表入射太阳辐射的影响,以及这种影响在不同年份的差异.借助WRF-Chem模式模拟分析了重污染期间气溶胶辐射效应对垂直方向上气象要素廓线、边界层结构以及PM_2.5浓度的反馈机制.结果表明:霾污染可导致大气透过率明显下降,春、秋、冬不同季节,霾污染导致中午大气透过率分别下降0.09,0.11和0.09.全年平均霾污染可导致大气透过率降低约15.5%.云量的增多也可导致大气透过率明显下降,多云天气下大气透过率相比晴天减小约22.4%.霾和云对大气透过率的影响还与太阳高度角有关,当太阳高度角>60°时,霾污染导致大气透过率下降8.6%.随污染等级提高,气溶胶对太阳辐射的衰减作用也越强,天津地区空气质量分别为Ⅰ～Ⅰ级时,中午地表入射短波辐射呈稳定下降趋势,依次为484,446,439,342,328和253W/m².重污染期间,气溶胶辐射效应导致大气低层(250m以下)降温(0.8℃)增湿(3.8%...     

阴燃中出现有焰火的理论初探

阴燃是一种自维持,不断传播的,异相反应的放热燃烧过程。典型的阴燃例子有蚝烟,地下煤矿的燃烧等。从热安全角度来看阴燃过程,不完全的氧化反应和可燃物热解都会产生很多的有毒气体,对人造成危害;另外在一定的条件下,阴燃还会突然转化为有焰火,进行更猛烈的燃烧,造成更大的破坏。     

Experimental study of recirculating flows generated by lateral shock waves in very large channels

Due to the lack of data on hydraulic-jump dynamics in very large channels, the present paper describes the main characteristics of the velocity field and turbulence in a large rectangular channel with a width of 4 m. Although a hydraulic jump is always treated as a wave that is transversal to the channel wall, in the case of this study it has a trapezoidal front shape, first starting from a point at the sidewalls and then developing downstream in an oblique manner, finally giving rise to a trapezoidal shape. The oblique wave front may be regarded as a lateral shockwave that arises from a perturbation at a certain point of the lateral wall and travels obliquely toward the centreline of the channel. The experimental work was carried out at the Coastal Engineering Laboratory of the Water Engineering and Chemistry Department of the Technical University of Bari (Italy). In addition to the hydraulic jump formation, a large recirculating flow zone starts to develop from the separating point of the lateral shock wave and a separate boundary layer occurs. Intensive measurements of the streamwise and spanwise flow velocity components along one-half width of the channel were taken using a bidimensional Acoustic Doppler Velocimeter (ADV). The water surface elevation was obtained by means of an ultrasonic profiler. Velocity vectors, transversal velocity profiles, turbulence intensities and Reynolds shear stresses were all investigated. The experimental results of the separated boundary layer were compared with numerical predictions and related work presented in literature and showed good agreement. The transversal velocity profiles indicated the presence of adverse pressure gradient zones and the law of the wall appears to govern the region around the separated boundary layer.     

城区与郊区PM2.5污染及传输特征差异性

基于云高仪激光雷达、飞机AMDAR数据和常规站点等多源观测数据,并与数值模拟（CAMx-PSAT模型）相结合,以京津冀典型城市——北京城区与郊区（密云）和石家庄城区与郊区（平山）为案例研究区域,对城区和郊区边界层高度差异（ΔPBLH）、地面PM_2.5浓度差异（ΔSurf_PM_2.5）、高空PM_2.5浓度差异（ΔVert_PM_2.5）和传输通量强度及高度分布特征差异进行分析.结果表明,由于人为热源、短波辐射和热力湍流等因素,导致城区年均边界层高度（PBLH）较郊区高8%~29%,且不同季节下城区PBLH月均较郊区高2%（石家庄4月）~47%（北京7月）.由于人为排放、逆温和大气湍流等共同作用,在0~1260 m之间等高度城区年均ρ（PM_2.5）较郊区高0.1（石家庄）~29.7（北京）μg ·m^-3,随高度增加而减小.城区年均总净通量强度远大于郊区,城区表现为流出,郊区表现为流入,是由于城区低压和郊区高压,形成城郊热力环流.北京城区和郊区与周边的年均总净通量强度之和（44.77 t ·d^-1）大于石家庄（34.44 t ·d^-1）.受风速和PM_2.5浓度的影响,在0~1260 m之间,城区和郊区与周边的净通量随离地高度的增加通量强度呈现明显增大趋势,其中1月城区和4月郊区与周边的传输交换对环境影响最为明显.不同季节下城区和郊区最大净通量的强度差异明显,两者相差2.23~4.48倍;但最大净通量强度的高度特征差异较小,主要位于611~1260 m.     

气象激光雷达的城市边界层探测

为了研究城市边界层结构变化特征,2005年7月利用气象激光雷达在南京城区做了城市边界层探测试验,就此次观测试验作了简要叙述并选取部分观测资料为示例,着重对气象激光雷达确定城市边界层高度垂直分布及逐时变化以及地面气象环境对边界层的日变化影响进行了初步分析.结果表明,主要由近地层对流混合形成的城市边界层高度具有典型的日变化特点,早晚比较低,日间有一个从低到高再到低的变化过程.提出了一种由边界层混合状态确定边界层高度的方法.分析结果表明,由气溶胶消光系数确定城市边界层高度比较准确.将MSL探测结果与同步的低空无线电探测仪的温度探测结果进行比较,结果表明,两者获得的实际廓线分布相当吻合,线性良好.就地表温度、辐射、湿度及云等气象要素对边界层垂直分布及时间变化的影响做了分析.结果表明,这些气象要素的分布对城市边界层高度的垂直分布及其逐时变化有明显影响.     

A numerical study of summer ozone concentration over the Kanto area of Japan using the MM5/CMAQ model

We assessed the ability of the MM5/CMAQ model to predict ozone (O3) air quality over the Kanto area and to investigate the factors that a ect simulation of O3. We find that the coupled MM5/CMAQ model is a useful tool for the analysis of urban environmental problems. The simulation results were compared with observational data and were found to accurately replicate most of the important observed characteristics. The initial and boundary conditions were found to have a significant e ect on simulated O3 concentrations. The results show that on hot and dry days with high O3 concentration, the CMAQ model provides a poor simulation of O3 maxima when using initial and boundary conditions derived from the CMAQ default data. The simulation of peak O3 concentrations is improved with the JCAP initial and boundary conditions. On mild days, the default CMAQ initial and boundary conditions provide a more realistic simulation. Meteorological conditions also have a strong impact on the simulated distribution and accumulation of O3 concentrations in this area. Low O3 concentrations are simulated during mild weather conditions, and high concentrations are predicted during hot and dry weather. By investigating the e ects of di erent meteorological conditions on each model process, we find that advection and di usion di er the most between the two meteorological regimes. Thus, di erences in the winds that govern the transport of O3 and its precursors are likely the most important meteorological drivers of ozone concentration over the central Kanto area.     

兰州西固工业区夏季光化学烟雾污染的气象条件

通过对兰州西固工业区光化学烟雾污染规律与气象条件的关系的研究表明,在高空槽后的低空弱高压控制下,西固区出现高的臭氧浓度值,此时大气层结稳定,风很小,天气晴朗,但中午有浓重烟雾,臭氧浓度峰值在中午出现。该区盆地内形成的光化学烟雾烟团水平面积达几十公里,臭氧浓度的日变化取决于太阳总辐射和大气边界层的日变化。