Associations of indoor carbon dioxide concentrations,air temperature,and humidity with perceived air quality and sick building syndrome symptoms in Chinese homes

The indoor environment influences occupants’ health. From March 1, 2018, to February 28, 2019, we continuously monitored indoor temperature (T), relative humidity (RH), and CO₂ concentration in bedrooms via an online system in 165 residences that covered all five climate zones of China. Meanwhile, we asked one specific occupant in each home to complete questionnaires about perceived air quality and sick building syndrome (SBS) symptoms at the end of each month. Higher CO₂ concentration was significantly associated with a higher percentage of perceived stuffy odor and skin SBS symptoms. Higher relative humidity was associated with higher percentage of perceived moldy odor and humid air, while lower RH was associated with a higher percentage of perceived dry air. Occupants who lived in residences with high RH were less likely to have mucosal and skin SBS symptoms (adjusted odds ratio (AOR): 0.73–0.78). However, the benefit of high humidity for perceived dry air and skin dryness symptoms is weaker if there is a high CO₂ concentration level.     

Stability and bifurcation in a stage-structured predator–prey system with Holling-II functional response and multiple delays

In this paper, we analyse a delayed Holling-II predator–prey system with stage-structure for the prey. At first, we study the stability and the existence of periodic solutions via Hopf bifurcation with respect to both delays at the positive equilibrium by analysing the distribution of the roots of the associated characteristic equation. Then, the explicit formula that determine the direction of the Hopf bifurcation and the stability of the bifurcating periodic solutions from the Hopf bifurcation are established by using the normal form method and centre manifold argument. Finally, some numerical simulations are carried out to support the main theoretical results.     

Attraction of Dibrachys cavus (Hymenoptera: Pteromalidae) to its Host Frass Volatiles

The European grapevine moth, Lobesia botrana (Lepidoptera: Tortricidae), is a polyphagous insect able to develop on grapes and wild plants. We tested the hypothesis that the parasitoid Dibrachys cavus (Hymenoptera: Pteromalidae) uses the larval frass in its host search. A two-armed olfactometer was used to measure the attractiveness of L. botrana larvae, their silk, or their frass after larvae were fed on different host plants. Frass of three Lepidoptera (L. botrana, Eupoecillia ambiguella, Sphinx ligustri) and one Orthoptera (Chorthippus brunneus) was assayed, but only L. botrana was used to test an effect of the larval host plant (two grape cultivars and three other plant species) to D. cavus females. Larvae without frass did not attract D. cavus whatever their origin, but their frass was attractive at a dose of 2–3 days equivalent of larval frass production. The silk produced by a single larva (L. botrana) was not attractive to D. cavus. The parasitoid was most attracted to the odor of S. ligustri; the frass of L. botrana was more attractive than that of E. ambiguella, irrespective of the species on which D. cavus had been reared. There was no difference in attractiveness of frass collected from L. botrana raised on food containing different plants. Chemical extracts using five different polarity solvents (acetone, dichloromethane, hexane, methanol, and water) differed in attractiveness to D. cavus. Water and dichloromethane were the most attractive. This suggests that a complex volatile signal made from intermediate to polar volatiles may be involved in attraction. D. cavus used frass to discriminate between different potential host species. Our results revealed that the larval food of L. botrana did not modify frass attractiveness, but that the moth species did.     

Age-structured predator–prey model with habitat complexity: oscillations and control

In this article, we study a predator–prey interaction in a homogeneously complex habitat where predator takes a fixed time to develop from immature to its mature stage. The age-structure of the predator and its interaction with the prey is framed in a system of delay differential equations. The objective is to study the role of habitat complexity and the maturation delay of the predator on the overall dynamics of the model system. Different interesting dynamical behaviours can be obtained by regulating two key parameters, namely the degree of habitat complexity and the maturation delay. It is observed that the system becomes unstable from its stable condition when the maturation delay crosses some critical value. The periodic solutions bifurcated from the interior equilibrium is found to be supercritical and stable. Synchronization of population fluctuations is, however, possible by increasing the strength of habitat complexity. The predator population goes to extinction and the prey population reaches to its maximum, irrespective of the length of maturation delay, when the habitat complexity crosses some upper critical value. The qualitative dynamical behaviours of the model system are verified with the data of Paramecium aurelia (prey) and Didinium nasutum (predator) interaction.     

Synthetic versus natural cat odorant effects on rodent behavior and medial amygdala plasticity.

Fear and anxiety behaviors are underpinned by neuronal changes within the amygdala. Here, the effects of exposure to natural and synthetic cat odor on behavior and amygdala plasticity were determined. Exposure to natural odor elicited typical and persistent anxiety-related behaviors, such as avoidance, freezing, and flat-back approach; however, synthetic odorant evoked no significant alteration in behavior. Furthermore, ex vivo induction of long-term potentiation within the medial nucleus of the amygdala, a principal area involved in olfactory perception, was significantly reduced after exposure to natural, but not synthetic, odor. Data presented here suggests that the synthetic odorant utilized may lack the constituents that are required to indicate predator presence in rodents and also the capacity to modulate neuronal plasticity within the medial nucleus of the amygdala. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

鱼类腥味脱除技术研究进展

鱼类的丰富营养和鲜美滋味使其成为餐桌上的优先选择,我国渔业资源丰富,但鱼类深加工技术却无法解决目前鱼类及其制品中存在的腥味问题,阻碍了淡水鱼加工产业的发展和新产品的开发。该文综述了淡水鱼类异味脱除的物理(流水暂养法、吸附法和包埋法等)、化学(酸碱盐处理法、抗氧化剂法及臭氧脱腥法等)以及生物(摄食法、酵母法、微生物酶法)方法,总结了鱼类脱腥技术的优缺点以及未来发展方向。     

具有恐惧效应和食饵避难所的Leslie - Gower捕食者-食饵模型的动力学分析

对一类具有恐惧效应和食饵避难所的Leslie - Gower捕食者- 食饵模型的动力学行为进行了研究.首先,利用吹胀的方法研究了模型原点的稳定性,并通过计算模型平衡点的雅可比矩阵研究了模型的边界和正平衡点的稳定性.然后,利用Dulac判别法证明了模型的唯一正平衡点是全局渐近稳定的,并讨论了恐惧效应和食饵避难所对食饵和捕食者种群密度的影响.最后,利用数值模拟验证了所得结果的正确性.     

Antipredator Defense of Biological Control Agent Oxyops vitiosa Is Mediated by Plant Volatiles Sequestered from the Host Plant Melaleuca quinquenervia

The weevil Oxyops vitiosa is an Australian species imported to Florida, USA, for the biological control of the invasive weed species Melaleuca quinquenervia. Larvae of this species feed on leaves of their host and produce a shiny orange secretion that covers the integument. When this secretion is applied at physiological concentrations to dog food bait, fire ant consumption and visitation are significantly reduced. Gas chromatographic analysis indicates that the larval secretion qualitatively and quantitatively resembles the terpenoid composition of the host foliage. When the combination of 10 major terpenoids from the O. vitiosa secretion was applied to dog food bait, fire ant consumption and visitation were reduced. When these 10 terpenoids were tested individually, the sesquiterpene viridiflorol was the most active component in decreasing fire ant consumption. Fire ant visitation was initially (15 min after initiation of the study) decreased for dog food bait treated with viridiflorol and the monoterpenes 1,8-cineole and -terpineol. Fire ants continued to avoid the bait treated with viridiflorol at 18 g/mg dog food for up to 6 hr after the initiation of the experiment. Moreover, ants avoided bait treated with 1.8 g/mg for up to 3 hr. The concentrations of viridiflorol, 1,8-cineole, and -terpineol in larval washes were about twice that of the host foliage, suggesting that the larvae sequester these plant-derived compounds for defense against generalist predators.     

给水中的致味物质及其检测方法

水中化学性或生物性致味物质是给水异味产生的来源,这些痕量异味物质的存在严重影响了给水的品质,因此给水中致味物质的富集、定性定量分析及去除等相关研究是近年来全世界都关注的一个重要课题。作者介绍了给水异味物质的分类与来源,阐述了国内外给水异味物质的感官及仪器检测方法,总结了国内外给水异味研究方面的差异,指出了CLSA—GC与SDE—GC互补使用是给水异味分析的最精确有效的手段。     

Differential effects of lesions of the vomeronasal and olfactory nerves on garter snake (Thamnophis sirtalis) responses to airborne chemical stimuli.

The roles of the main (MOS) and accessory (AOS) olfactory systems of garter snakes in response to airborne chemicals were investigated. Preoperatively, all snakes responded to airborne odors with increased tongue-flick rate and duration. Postoperatively, sham-operated snakes responded to airborne odors with increased tongue-flick rates, but snakes with main olfactory nerve cuts failed to respond to the odors, and snakes with vomeronasal nerve cuts responded to nonprey odors only. Preoperatively, exposure to earthworm odor produced more frequent and shorter duration tongue-flicks during locomotion compared with exposure to water. Postoperatively, only sham-lesioned snakes exhibited differential responding to earthworm odors. This study demonstrates that the MOS is critical for the initiation of tongue-flick behavior in response to airborne odors and that discrimination of odors with biological significance requires a functional AOS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)