Predicting adaptive behavior in the environment from central nervous system dynamics

To generate adaptive behavior, the nervous system is coupled to the environment. The coupling constrains the dynamical properties that the nervous system and the environment must have relative to each other if adaptive behavior is to be produced. In previous computational studies, such constraints have been used to evolve controllers or artificial agents to perform a behavioral task in a given environment. Often, however, we already know the controller, the real nervous system, and its dynamics. Here we propose that the constraints can also be used to solve the inverse problem--to predict from the dynamics of the nervous system the environment to which they are adapted, and so reconstruct the production of the adaptive behavior by the entire coupled system. We illustrate how this can be done in the feeding system of the sea slug Aplysia. At the core of this system is a central pattern generator (CPG) that, with dynamics on both fast and slow time scales, integrates incoming sensory stimuli to produce ingestive and egestive motor programs. We run models embodying these CPG dynamics--in effect, autonomous Aplysia agents--in various feeding environments and analyze the performance of the entire system in a realistic feeding task. We find that the dynamics of the system are tuned for optimal performance in a narrow range of environments that correspond well to those that Aplysia encounter in the wild. In these environments, the slow CPG dynamics implement efficient ingestion of edible seaweed strips with minimal sensory information about them. The fast dynamics then implement a switch to a different behavioral mode in which the system ignores the sensory information completely and follows an internal "goal," emergent from the dynamics, to egest again a strip that proves to be inedible. Key predictions of this reconstruction are confirmed in real feeding animals.     

Modeling the human body/seat system in a vibration environment

The vibration environment is a common man-made artificial surrounding with which humans have a limited tolerance to cope due to their body dynamics. This research studied the dynamic characteristics of a seated human body/seat system in a vibration environment. The main result is a multi degrees of freedom lumped parameter model that synthesizes two basic dynamics: (i) global human dynamics, the apparent mass phenomenon, including a systematic set of the model parameters for simulating various conditions like body posture, backrest, footrest, muscle tension, and vibration directions, and (ii) the local human dynamics, represented by the human pelvis/vibrating seat contact, using a cushioning interface. The model and its selected parameters successfully described the main effects of the apparent mass phenomenon compared to experimental data documented in the literature. The model provided an analytical tool for human body dynamics research. It also enabled a primary tool for seat and cushioning design. The model was further used to develop design guidelines for a composite cushion using the principle of quasi-uniform body/seat contact force distribution. In terms of evenly distributing the contact forces, the best result for the different materials and cushion geometries simulated in the current study was achieved using a two layer shaped geometry cushion built from three materials. Combining the geometry and the mechanical characteristics of a structure under large deformation into a lumped parameter model enables successful analysis of the human/seat interface system and provides practical results for body protection in dynamic environment.     

Human immunity system under conditions of 105-day isolation and confinement in an artificial environment

The study of the adaptive immunity system of six test subjects volunteered for a 105-day isolation and confinement in an artificial environment showed activation of the immune system and overstrain and depletion of its functional reserve. Significant differences in the adaptability of the immune system of the test subjects indicate individual susceptibility to disorders in immunological reactivity.     

不同坡位沙棘光合日变化及其主要环境因子

沙棘是我国干旱半干旱地区重要的生态经济树种,被广泛应用于黄土高原造林活动中。为探明不同坡位沙棘光合特征及影响沙棘光合作用的主要环境因子,在沙棘生长旺盛期分坡位测定光合特性及环境因子日变化进程,并采用通径分析法分析各环境因子对沙棘净光合速率的直接和间接影响。结果表明：1、各环境因子之间存在相互作用,光合有效辐射是空气温度变化的主要驱动因子,而空气温度变化引起的空气密度变化对空气相对湿度和CO2浓度有显著影响。在上、中和下坡位环境变化可以分别解释85.6%、86.0%和 55.22%净光合速率的变异。2、下坡位沙棘净光合速率最小,日均值为9.38μmol/m2/s,上、中坡位分别为14.22μmol/m2/s,15.94μmol/m2/s。3、10:00之前中上坡位沙棘水分利用效率明显高于下坡位,但3坡位沙棘水分利用效率日均值无明显差异。4、上坡位净光合速率主要受到光合有效辐射、空气相对湿度的影响;中坡位光合有效辐射仍为主要环境因子,此外空气温度和空气湿度之间的相互作用对净光合速率也有一定影响,为主要限制因子;下坡位影响沙棘光合速率主导因素为光合有效辐射。5、沙棘在10:00之前光合有效辐射和空气湿度较高而空气温度较低的环境下,净光合速率和水分利用效率最高。作为阳生物种,沙棘需要足够的光照维持生长,而以往研究表明适度水分胁迫可以提高沙棘光合过程中对水的利用效率。本研究所选流域年降水量535mm,中上坡位水分胁迫并非十分严重。因此,种植于中上坡位的沙棘即可接受足够光照（特别是10:00以前的光照）进行光合保证生长速率,又能在光合过程中保持较高水分利用效率,符合干旱半干旱地区生态经济发展的需求。     

分株比例对异质光环境下美丽箬竹克隆系统光合生理的影响

分株数量或生物量比例差异会明显影响克隆系统对资源异质性环境的生态适应性, 地下茎木质化、连接稳固的竹类植物在生长过程中相连克隆分株通常会生活在异质光环境中, 但其叶片光合生理特性对异质光环境的响应及其分株比例效应则未见报道。该研究以地下茎相连的美丽箬竹(Indocalamus decorus)克隆系统为实验材料, 设置2个遮光率(分别为50% ± 5%和75% ± 5%)和3个分株比例(遮光与未遮光分株比例分别为1:3、2:2、3:1)处理, 分株数量为4株。分别测定了遮光处理后30、90、150天遮光和未遮光分株叶片光响应特征、气体交换参数、光合色素含量, 分析了异质光环境下美丽箬竹光合生理的变化规律。结果显示: 分株比例对美丽箬竹光合生理有显著影响, 且其与遮光、处理时间交互作用显著。美丽箬竹克隆系统遮光分株比例越大, 即遮光相对分株数量越多, 其表观量子效率(AQE)、光饱和点、最大净光合速率(P_{n max})、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、水分利用效率越大, 光补偿点、暗呼吸速率越小, 其光合效率越高, 光能利用能力越强, 而与之相连的未遮光分株则相反; 随遮光分株比例的增大, 遮光分株叶片叶绿素a、叶绿素b含量呈先升高而后下降的变化趋势, 类胡萝卜素(Car)含量则持续下降, 而与之相连的未遮光分株叶片光合色素含量则呈下降趋势; 遮光率提高, 相同分株比例美丽箬竹克隆系统遮光分株叶片AQE、P_{n max}、P_n、G_s、胞间CO₂浓度(C_i)和光合色素含量总体升高, 而与之相连的未遮光分株叶片P_{n max}、C_i以及Car含量则总体下降。研究结果表明异质光环境下, 遮光分株光合效率和弱光利用能力明显增强, 而未遮光分株则相反, 克隆系统内分株间发生了明显的克隆分工, 且2:2、3:1分株比例克隆系统较1:3分株比例对异质光环境具有更好的适应能力。美丽箬竹克隆系统可通过差异性调节分株光合生理特性和光合色素含量, 提高遮光分株光能利用和光合效率来适应异质光环境, 以提高克隆系统的适合度。     

Photosynthetic Physiological Characteristics of Tetracentron sinense Oliv in Different DBH Classes and the Factors Restricting Regeneration

Tetracentron sinense is an endangered tree species mainly distributed in Western China. In natural population of T. sinense, fewer young individuals and their concentration in the forest understory, whereas middle-aged individuals gradually transited from the understory to the forest gap and edge habitats, resulting in poverty natural population regeneration. Individuals from different age classes of T. sinense may differ in their photosynthetic adaptability to the different light conditions in the understory, forest gaps and forest edges. Whether these differences are the main factors limiting the natural regeneration of this species remains unclear. This study aims at elucidate the changes in photosynthetic physiological characteristics with age, and discuss the effective conservation and management strategies for this species. We used the Li-6400XT photosynthetic analyzer to examine the photosynthesis characteristics (including P_n-PAR, P_n-CO₂ and SLA) of T. sinense individuals of different diameters at breast height (DBH) classes, and analyzed the different DBH individuals' differences in photosynthetic and physiological. The results showed that the photosynthetic adaptability of T. sinense to a light environment would be different throughout the life cycle. The ability to adapt to the light environment, CO₂ utilization potential and accumulation of photosynthetic substances was significantly higher in the reproductive initiation stage of T. sinense than other stages. T. sinense individuals' environmental adaptability in the pre-reproductive stage was relatively weak, which may be one of the main factors limiting natural regeneration. Therefore, the area of forest gaps in T. sinense natural populations should be expanded by artificial interference to facilitate the growth of young individuals and promote population regeneration.

     

光环境对胡桃楸幼苗生长与光合作用的影响

为了解胡桃楸幼苗对光的需求及适应规律,采用Li-6400便携式光合测定系统研究了不同光环境处理（100%、60%、30％和15%自然光）条件下3年生胡桃楸幼苗（适应1年后）叶片光合能力的季节变化及其对光强的响应.结果表明：在春季,胡桃楸幼苗对光反应不敏感,夏季和秋季随着光强的增加,叶片的最大光合速率、最大羧化速率和最大电子传递速率均显著增加（P<0.05）.光饱和点随光强的下降而降低（P<0.05）,表观量子效率、暗呼吸速率和光补偿点在不同光环境下未发现显著差异.100%和60%自然光处理的幼苗相对生长率差异不显著,但是随着光强下降,相对生长率显著下降（P<0.05）,为60%>30％>15%自然光处理.胡桃楸幼苗对不同的光环境表现出较强的适应性和可塑性;同时,通过降低光饱和点和减少碳积累,也能适应15%～30％自然光环境.     

Physical behaviour of anthropogenic light propagation into the nocturnal environment

Propagation of artificial light at night (ALAN) in the environment is now known to have non negligible consequences on fauna, flora and human health. These consequences depend on light levels and their spectral power distributions, which in turn rely on the efficiency of various physical processes involved in the radiative transfer of this light into the atmosphere and its interactions with the built and natural environment. ALAN can affect the living organisms by direct lighting and indirect lighting (scattered by the sky and clouds and/or reflected by local surfaces). This paper mainly focuses on the behaviour of the indirect light scattered under clear sky conditions. Various interaction processes between anthropogenic light sources and the natural environment are discussed. This work mostly relies on a sensitivity analysis conducted with the light pollution radiative transfer model, Illumina (Aubé et al. 2005 Light pollution modelling and detection in a heterogeneous environment: toward a night-time aerosol optical depth retrieval method. In Proc. SPIE 2005, vol. 5890, San Diego, California, USA). More specifically, the impact of (i) the molecular and aerosol scattering and absorption, (ii) the second order of scattering, (iii) the topography and obstacle blocking, (iv) the ground reflectance and (v) the spectrum of light devices and their angular emission functions are examined. This analysis considers different behaviour as a function of the distance from the city centre, along with different zenith viewing angles in the principal plane.     

Proposal for a framework for optimizing artificial environments based on physiological feedback

We propose and then evaluate a new framework for finding the physical parameters of an artificial environment which give rise to given target physiological characteristics. We assume that a human is a system that takes as inputs the physical parameters of an artificial environment and outputs physiological parameters in response. We define our task as the inverse problem; we must find the best inputs from given target outputs. Our proposed framework solves the inverse problem using evolutionary computation techniques to optimize an artificial environment. We evaluate this framework using a simulation with a vibration environment and verify that it works.     

Modeling of pain using artificial neural networks

In dealing with human nervous system, the sensation of pain is as sophisticated as other physiological phenomena. To obtain an acceptable model of the pain, physiology of the pain has been analysed in the present paper. Pain mechanisms are explained in block diagram representation form. Because of the nonlinear interactions existing among different sections in the diagram, artificial neural networks (ANNs) have been exploited. The basic patterns associated with chronic and acute pain have been collected and then used to obtain proper features for training the neural networks. Both static and dynamic representations of the ANNs were used in this regard. The trained networks then were employed to predict response of the body when it is exposed to special excitations. These excitations have not been used in the training phase and their behavior is interesting from the physiological view. Some of these predictions can be inferred from clinical experimentations. However, more clinical tests have to be accomplished for some of the predictions.     

贵州石漠化区布依族传统村落人居环境适宜度

为了解传统村落人居环境对石漠化及地形地貌的适应性,采用德尔菲法、综合权重法确定了石漠化区布依族传统村落人居环境适宜度评价指标体系及权重,并收集指标数据和确定人居环境适宜度值与阈值,综合分析了人居环境适宜度.结果表明: 10%的布依族传统村落位于强度与极强度石漠化区,且有择优环境的传统;人居环境适宜度指标体系由经济、历史文化、生态、社会、建筑环境适宜度5个一级指标及26个二级指标组成,该指标体系对喀斯特区村落均适宜;总体上,综合环境适宜度值(2.81～3.77)与经济(0.77～1.17)、历史文化(0.39～0.50)、生态(0.83～1.07)、社会环境(0.38～0.53)适宜度值随石漠化强度递增而递减,而建筑(0.43～0.51)则无显著变化,石漠化对经济、历史文化、生态和社会环境影响深远且有协同关系;人居环境适宜度阈值下限为2.93,低于2.93可考虑搬迁或采取措施提高其值;山地半坡传统村落人居环境适宜度值(3.56)高于洼地(3.42)和谷地(3.16);石漠化区传统村落人居环境适宜度比普通村落高,但低于常态地貌,其主因是经济与生态的差异;石漠化区传统村落人居环境提升应加强石漠化综合治理及政策支撑,发展生态经济与旅游及保护历史文化或生态移民.本研究可为喀斯特区村落人居环境保护规划、建设等提供理论依据.     

Perspectives on environmental adaptability and physiological polymorphism in thermoregulation

The environmental adaptability of human beings has progressed according to various environments experienced in the course of evolution. Therefore, various phenotypes for environmental adaptability exist and are considered to be physiological polymorphism. Physiological polymorphism in thermoregulation is influenced by genotype, individual characteristics, environmental factors, cultural factors, etc. Moreover, it is thought that physiological polymorphism is evidenced more clearly in physiological responses to extreme situations and/or changing conditions than in environments where homeostasis is easily maintained. In the field of physiological anthropology, I think that it is important not only to discover the physiological responses that demonstrate polymorphism, but also to hypothesize about the mechanisms and the processes by which such polymorphisms were formed, and their meaning for human beings. Such discussions may be supposed to lead to an evaluation of the environmental adaptability of humans from the viewpoint of physiological anthropology.     

Autonomic dysfunction in women with fibromyalgia

Fibromyalgia (FM) is an idiopathic disease characterized by widespread pain and a myriad of symptoms. Symptoms are diverse and include not only pain but also anxiety, depression, orthostatic intolerance, and cold intolerance. While the etiology of FM is not fully understood, data have suggested that FM may stem from dysfunction of the autonomic nervous system. This dysfunction has been reported at rest, and after a physiological stressor such as exercise. However, few studies have examined the responses during exercise. This novel approach may shed some new light on the effect of exercise in women with FM.     

生态适应性在植物水生诱导上的运用

本文通过论述植物普遍存在的生态适应性与环境变化对适应性形成及进化上的影响,以及植物生态适应性形成过程中胁迫环境的重要性,分析了植物水生诱导过程中相关的生理生化及生态方面的变化规律,提出了利用人工环境模拟技术来促进植物通气组织形成的技术路线,形成一套完整可操作的植物水生诱变操作流程,并展现了植物水生诱变技术在生产、生活、生态上的广阔应用前景。     

Cascading effects of artificial light at night: resource-mediated control of herbivores in a grassland ecosystem

Artificial light at night has a wide range of biological effects on both plants and animals. Here, we review mechanisms by which artificial light at night may restructure ecological communities by modifying the interactions between species. Such mechanisms may be top-down (predator, parasite or grazer controlled), bottom-up (resource-controlled) or involve non-trophic processes, such as pollination, seed dispersal or competition. We present results from an experiment investigating both top-down and bottom-up effects of artificial light at night on the population density of pea aphids Acyrthosiphon pisum in a diverse artificial grassland community in the presence and absence of predators and under low-level light of different spectral composition. We found no evidence for top-down control of A. pisum in this system, but did find evidence for bottom-up effects mediated through the impact of light on flower head density in a leguminous food plant. These results suggest that physiological effects of light on a plant species within a diverse plant community can have detectable demographic effects on a specialist herbivore.     

Physiological model analysis of involuntary human-voice tremor

Frequency variations in the human voice result from voluntary and involuntary changes in the parameters of the vocal system. The present work deals with involuntary frequency perturbations from two theoretical aspects: 1) the influence of pitch period variations on frequency changes in the band-limited signal which results from the resonant characteristics of the vocal tract; 2) the physiological parameters of the vocal system which are potentially able to govern involuntary frequency changes. It is shown that the modulation function of the vocal-cord wave can theoretically be derived from its harmonics using FM demodulation techniques, and that higher distortion may appear at higher harmonics. It is also shown that involuntary geometrical changes of the vocal tract and its terminal impedance as well as tension and initialarea changes of the vocal cord—changes well within the physiological range—can influence frequency changes in the human voice. The present results are correlated with our reported experimental findings on involuntary voice tremor, used in psychological stress evaluation. The role of the central nervous system, and possible mechanisms for these phenomena, are discussed.     

长春花(Catharanthus roseus)对热带珊瑚岛生理生态适应性研究

长春花(Catharanthus roseus)是夹竹桃科的一种亚灌木植物,具有重要的药用价值和观赏价值,在前期的试验性种植中,发现长春花对热带珊瑚岛环境有很强的适应性。为了探讨长春花对热带珊瑚岛环境的生理生态适应性,该文以移植到热带珊瑚岛的长春花和生长于海南省文昌市苗圃的长春花为研究对象,对其叶片的形态解剖结构、生理学特征、营养元素含量等进行了分析。结果表明:(1)与苗圃生长的长春花和其他耐胁迫的植物相比,移植到热带珊瑚岛上的长春花具有叶片厚、栅栏组织发达、比叶面积小等形态解剖特征,这些特征有利于其光能吸收、水分储存和对环境资源的利用。(2)长春花的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性较高,表现出较强的抗氧化性和抗胁迫能力。(3)长春花的叶绿素a和叶绿素b含量较低,可以减少过多的光能进入叶绿体光合系统,防止过剩的光能对光合系统产生伤害。(4)热带珊瑚岛土壤养分含量低,但生长在岛上的长春花叶片的营养元素含量高,表现出很强的养分吸收和利用能力。因此,长春花对干旱、贫瘠等恶劣生境具有很好的适应能力,可以作为热带珊瑚岛植被恢复工具种。     

Evidence for "memory" of cervical stimulation for the promotion of pregnancy in rats

Successful pregnancy in the female rat depends upon two sets of physiological events: (1) transport of gametes (sperm and egg) through the reproductive tract so that fertilization can be effected and (2) establishment of an appropriate hormonal environment (progestational state) so that the fertilized egg can implant in the uterus and be maintained during subsequent gestation. This study highlights the independence of the mechanisms controlling the gametic and hormonal aspects of pregnancy by temporally separating the introduction of sperm into the female from the stimulation that triggers the progestational hormonal response. The progestational state was initiated by electrical stimulation of the cervix, and sperm was introduced directly into the uterus by artificial insemination. Although these two events were separated by up to 3 days, pregnancy could ensue. Cervical stimulation, normally a consequence of male intromission behavior, establishes a condition in the central nervous system, a "memory" that signals the probable induction of pregnancy. Without this "memory," animals with a short estrous cycle would continue to cycle after mating, thereby producing a hormonal environment incompatible with implantation. The "memory" is manifested by daily surges of prolactin irrespective of fertilization. This is the first physiological demonstration that a "memory" of cervical stimulation can be called upon to support a viable pregnancy.     

A model of force and impedance in human arm movements

This paper describes a simple computational model of joint torque and impedance in human arm movements that can be used to simulate three-dimensional movements of the (redundant) arm or leg and to design the control of robots and human-machine interfaces. This model, based on recent physiological findings, assumes that (1) the central nervous system learns the force and impedance to perform a task successfully in a given stable or unstable dynamic environment and (2) stiffness is linearly related to the magnitude of the joint torque and increased to compensate for environment instability. Comparison with existing data shows that this simple model is able to predict impedance geometry well.