基于深度强化学习的耕作层土壤水分、温度预测

【目的】利用土壤近表面空气温湿度与土壤内部参数的关联关系对耕作层土壤水分、温度进行精准预测,为实现精细化农业种植管理提供服务。【方法】针对土壤耕作层水分、温度预测在训练集获取与模型验证等方面的实际需求,设计了基于嵌入式系统及窄带物联网(Narrow band internet of things,NB-IoT)无线通信技术的物联网数据采集系统。在此基础上基于深度Q学习(Deep Q network,DQN)算法探索了一种模型组合策略,以长短期记忆(Long short-term memory,LSTM)、门限循环单元(Gated recurrent unit,GRU)与双向长短期记忆网络(Bidirectional long short-term memory,Bi-LSTM)为基础模型进行加权组合,获得了DQN-L-G-B组合预测模型。【结果】数据采集系统实现了对等间隔时间序列环境数据的长时间稳定可靠采集,可以为基于深度学习的土壤水分、温度时间序列预测工作提供准确的训练集与验证集数据。相对于LSTM、Bi-LSTM、GRU、L-G-B等模型,DQN-L-G-B组合模型在2种土壤类型(...     

Instrumental learning of vasomotor responses by rats: learning to respond differentially in the two ears

Curarized and artificially respirated rats were rewarded by electrical stimulation of the brain for changes in the balance of vasomotor activity between the two ears. They learned vasomotor responses in one ear that were independent of those in the other ear, in either forepaw, or in the tail, or of changes in heart rate or temperature. In addition to implications for learning theory and psychosomatic medicine, these results indicate a greater specificity of action in the sympathetic nervous system than is usually attributed to it.     

Training and maintenance of keypecking in the pigeon by negative reinforcement

Pigeons were trained to peck a key to escape a pulsing shock of linearly increasing intensity. As the rate of increase was varied from 0.0374 milliamperes per minute to 37.4 milliamperes per minute, the intensity at which most pecking occurred varied from 2.2 to 5.0 milliamperes.     

Hold your horses: impulsivity, deep brain stimulation, and medication in parkinsonism

Deep brain stimulation (DBS) of the subthalamic nucleus markedly improves the motor symptoms of Parkinson's disease, but causes cognitive side effects such as impulsivity. We showed that DBS selectively interferes with the normal ability to slow down when faced with decision conflict. While on DBS, patients actually sped up their decisions under high-conflict conditions. This form of impulsivity was not affected by dopaminergic medication status. Instead, medication impaired patients' ability to learn from negative decision outcomes. These findings implicate independent mechanisms leading to impulsivity in treated Parkinson's patients and were predicted by a single neurocomputational model of the basal ganglia.     

Maternal influence in learning by observation in kittens

Kittens who observed their mothers perform a stimulus-controlled response (lever pressing to a visual stimulus for food) acquired and discriminated that response sooner than kittens who observed a strange female cat's performance. Kittens exposed to a trial and error condition never acquired the response. Initial differences in attentiveness to demonstrator performances disappeared by the second day. "Altruism" (food sharing) and other forms of social behavior were exhibited by both mother and stranger demonstrators.     

Memory extinction, learning anew, and learning the new: dissociations in the molecular machinery of learning in cortex

The rat insular cortex (IC) subserves the memory of conditioned taste aversion (CTA), in which a taste is associated with malaise. When the conditioned taste is unfamiliar, formation of long-term CTA memory depends on muscarinic and beta-adrenergic receptors, mitogen-activated protein kinase (MAPK), and protein synthesis. We show that extinction of CTA memory is also dependent on protein synthesis and beta-adrenergic receptors in the IC, but independent of muscarinic receptors and MAPK. This resembles the molecular signature of the formation of long-term memory of CTA to a familiar taste. Thus, memory extinction shares molecular mechanisms with learning, but the mechanisms of learning anew differ from those of learning the new.     

节水灌溉技术采用及其增产效应评估——以延津县318户胡萝卜种植户为例

为了加快节水灌溉技术推广和普及,采用内生转换回归模型分析农户节水灌溉技术采用行为,并评估节水灌溉技术的增产效应,结果表明,节水灌溉技术的增产效应十分显著,能够使农户每hm2胡萝卜产量增加约7 961kg,相当于单产水平的21%。户主受教育程度、家庭在外务工人数和技术采用经历对农户节水灌溉技术采用行为影响显著;生产规模大、参与产销合作的农户也会更倾向于采用节水灌溉技术。根据研究结论,本研究最后提出了4点政策建议:1)努力提升农户受教育程度;2)积极推进耕地适度规模经营;3)大力推广产销合作模式;4)加强节水灌溉技术推广力度。     

Ciliary orientation: controlled by cell membrane or by intracellular fibrils?

The cirri of the ciliate Euplotes all asslumne the "reversed" orientation whenever the cell is depolarized and the "forward" orientation whenever the cell is hyperpolarized. Potenitial changes arise spontaneolusly or are induced by electrical or mechanical stimuli. The orientation responses of thte cirri are appatently independent of intracellular "neuromotor" fibrils previously assigned a coordinating function, as they persist after the fibrils are transected.     

Associative learning in egglaying site selection by apple maggot flies

Evidence is presented demonstrating that associative learning during oviposition in Crataegus or apple hosts can significantly influence the propensity of apple maggot flies to accept or reject these hosts in future encounters. The data suggest that within resource patches of a given host type there may be an enhancement of foraging efficiency.     

The inversion of sensory processing by feedback pathways: a model of visual cognitive functions

The mammalian visual system has a hierarchic structure with extensive reciprocal connections. A model is proposed in which the feedback pathways serve to modify afferent sensory stimuli in ways that enhance and complete sensory input patterns, suppress irrelevant features, and generate quasi-sensory patterns when afferent stimulation is weak or absent. Such inversion of sensory coding and feature extraction can be achieved by optimization processes in which scalar responses derived from high-level neural analyzers are used as cost functions to modify the filter properties of more peripheral sensory relays. An optimization algorithm, Alopex, which is used in the model, is readily implemented with known neural circuitry. The functioning of the system is investigated by computer simulations.     

Sink or swim: strategies for cost-efficient diving by marine mammals

Locomotor activity by diving marine mammals is accomplished while breath-holding and often exceeds predicted aerobic capacities. Video sequences of freely diving seals and whales wearing submersible cameras reveal a behavioral strategy that improves energetic efficiency in these animals. Prolonged gliding (greater than 78% descent duration) occurred during dives exceeding 80 meters in depth. Gliding was attributed to buoyancy changes with lung compression at depth. By modifying locomotor patterns to take advantage of these physical changes, Weddell seals realized a 9.2 to 59.6% reduction in diving energetic costs. This energy-conserving strategy allows marine mammals to increase aerobic dive duration and achieve remarkable depths despite limited oxygen availability when submerged.     

Amnesia produced by electroconvulsive shock or cycloheximide: conditions for recovery

Retrograde amnesia for a passive avoidance response was produced in rats by electroconvulsive shock and in mice by cycloheximide, an inhibitor of protein synthesis. One day after training the memory could be restored if a "reminder" of the original foot shock was given after the retention test on which the amnesia was demonstrated. Memory did not return if the reminder was given without the prior retention test or if the reminder and the test were separated by 23 hours.     

基于机器学习的江汉平原土壤有机碳预测及制图

土壤有机碳（SOC）不仅显著响应于表层,而且随深度的变化呈现不同的响应。江汉平原作为长江经济带农田生态系统的重要组成部分,其SOC垂向分布状况仍有待考察。本研究收集了2009—2012年湖北省土系调查的66个剖面数据,基于9个环境因子为协变量使用随机森林法构建 0~30、>30~60、>60~100 cm土层深度的 SOC含量预测模型,绘制了 30 m空间分辨率的 SOC含量分布图,并估算了 SOC 储量。结果表明,SOC 含量随土层深度的增加而减少,总体呈中东部高、西部低的特征。模型对表层（0~30 cm）SOC的预测精度最高（R²=0.45,RMSE=3.28 g·kg^-1）,温度、黏粒含量和降水对模型重要性居前三。江汉平原 1 m深 SOC储量为 183.75 Tg,>30~100 cm土层 SOC储量约占 1 m深度总储量的 59%。因此,土壤碳库估算及固碳潜力评估时需着重考虑深层土壤。本研究可为掌握SOC空间分布及垂直分异的响应规律提供参考。