Dynamic optimization of odor representations by slow temporal patterning of mitral cell activity

Mitral cells (MCs) in the olfactory bulb (OB) respond to odors with slow temporal firing patterns. The representation of each odor by activity patterns across the MC population thus changes continuously throughout a stimulus, in an odor-specific manner. In the zebrafish OB, we found that this distributed temporal patterning progressively reduced the similarity between ensemble representations of related odors, thereby making each odor's representation more specific over time. The tuning of individual MCs was not sharpened during this process. Hence, the individual responses of MCs did not become more specific, but the odor-coding MC assemblies changed such that their overlap decreased. This optimization of ensemble representations did not occur among olfactory afferents but resulted from OB circuit dynamics. Time can therefore gradually optimize stimulus representations in a sensory network.     

Equipotentiality quantified: the anatomical distribution of the engram

Sensory events and the representation of past experience cause distinctive changes in the electrical activity of widespread regions of the brain. These regions have similar roles in the engram in the sense that they all seem to participate in responses to external events and in subsequent representations of these events. However, the relative contribution of these processes to the activity of different brain regions is quantitatively different, in that some regions are much more strongly affected than others. These results may constitute the basis for reconciliation of localizationist and antilocalizationist views of brain function.     

雕塑艺术在园林中的体现

中国园林雕塑源远流长,“石头”文化开创了园林雕塑的先河,它体现着一种文化和审美,象征着一种精神和意境。雕塑是环境艺术,它具有依附性,雕塑家的作品创作仅仅是完成了室内创作的一部分,园林雕塑重要的是要接受大环境的检验,一件优秀的作品,是艺术和环境诸方面的统一体,“神形兼备”是艺术的最高境界,只有形与神、神与境的完美统一才是园林雕塑的完美体现。     

Endogenous knowledge and practice regarding the environment in a Nahua community in Mexico

We expose some representations and practices related to the natural environment among Nahua peasants in a village located at the western boundary of Puebla and Guerrero states, in Mexico. Information was obtained by individual interviews and focal groups' work, following an open guide with ecological items considered as rooted in Mesoamerican cultures. The use of some local, vegetal resources, and the local perception of changes, mainly in the water availability, is documented. Survival strategies involve ancestral representations and material products, and entail a high grade of pragmatism. “Natural environment” is framed in a local culture that involves relational and sacred dimensions, usually omitted in other approaches. Hence, for the Temalac peasants, there is no dissection, at an operative level, between “natural facts” (for instance, water availability) and personal or social ones, being these often considered as determinant for the quality and accessibility of resources and weather conditions. We discuss the challenge for these elements posed by a growing migration rate and an increasing external influence.     

Reorganization of retinotopic cortical maps in adult mammals after lesions of the retina

The organization of the visual cortex has been considered to be highly stable in adult mammals. However, 5 degrees to 10 degrees lesions of the retina in the contralateral eye markedly altered the systematic representations of the retina in primary and secondary visual cortex when matched inputs from the ipsilateral eye were also removed. Cortical neurons that normally have receptive fields in the lesioned region of the retina acquired new receptive fields in portions of the retina surrounding the lesions. The capacity for such changes may be important for normal adjustments of sensory systems to environmental contingencies and for recoveries from brain damage.     

Reshaping the cortical motor map by unmasking latent intracortical connections

The primary motor cortex (MI) contains a map organized so that contralateral limb or facial movements are elicited by electrical stimulation within separate medial to lateral MI regions. Within hours of a peripheral nerve transection in adult rats, movements represented in neighboring MI areas are evoked from the cortical territory of the affected body part. One potential mechanism for reorganization is that adjacent cortical regions expand when preexisting lateral excitatory connections are unmasked by decreased intracortical inhibition. During pharmacological blockade of cortical inhibition in one part of the MI representation, movements of neighboring representations were evoked by stimulation in adjacent MI areas. These results suggest that intracortical connections form a substrate for reorganization of cortical maps and that inhibitory circuits are critically placed to maintain or readjust the form of cortical motor representations.     

Neural representations of location composed of spatially periodic bands

The mammalian hippocampal formation provides neuronal representations of environmental location, but the underlying mechanisms are poorly understood. Here, we report a class of cells whose spatially periodic firing patterns are composed of plane waves (or bands) drawn from a discrete set of orientations and wavelengths. The majority of cells recorded in parasubicular and medial entorhinal cortices of freely moving rats belonged to this class and included grid cells, an important subset that corresponds to three bands at 60° orientations and has the most stable firing pattern. Occasional changes between hexagonal and nonhexagonal patterns imply a common underlying mechanism. Our results indicate a Fourier-like spatial analysis underlying neuronal representations of location, and suggest that path integration is performed by integrating displacement along a restricted set of directions.     

H2S induces a suspended animation-like state in mice

Mammals normally maintain their core body temperature (CBT) despite changes in environmental temperature. Exceptions to this norm include suspended animation-like states such as hibernation, torpor, and estivation. These states are all characterized by marked decreases in metabolic rate, followed by a loss of homeothermic control in which the animal's CBT approaches that of the environment. We report that hydrogen sulfide can induce a suspended animation-like state in a nonhibernating species, the house mouse (Mus musculus). This state is readily reversible and does not appear to harm the animal. This suggests the possibility of inducing suspended animation-like states for medical applications.     

Representation of perceived object shape by the human lateral occipital complex

The human lateral occipital complex (LOC) has been implicated in object recognition, but it is unknown whether this region represents low-level image features or perceived object shape. We used an event-related functional magnetic resonance imaging adaptation paradigm in which the response to pairs of successively presented stimuli is lower when they are identical than when they are different. Adaptation across a change between the two stimuli in a pair provides evidence for a common neural representation invariant to that change. We found adaptation in the LOC when perceived shape was identical but contours differed, but not when contours were identical but perceived shape differed. These data indicate that the LOC represents not simple image features, but rather higher level shape information.     

准两优1202双季稻免耕抛秧连片示范总结

双季免耕连片种植示范准两优1202情况表明：该组合田间表现分蘖力强,前中期株型松紧适中,成熟前一周株型转松散,剑叶稍大,茎秆粗壮,根系发达,结实率高,对纹枯病、稻瘟病抗性较好。其生育特性、丰产性、适应性表现都很适应双季免耕栽培,可在双季稻地区大面积推广。     

A yeast prion, Mod5, promotes acquired drug resistance and cell survival under environmental stress

Prion conversion from a soluble protein to an aggregated state may be involved in the cellular adaptation of yeast to the environment. However, it remains unclear whether and how cells actively use prion conversion to acquire a fitness advantage in response to environmental stress. We identified Mod5, a yeast transfer RNA isopentenyltransferase lacking glutamine/asparagine-rich domains, as a yeast prion protein and found that its prion conversion in yeast regulated the sterol biosynthetic pathway for acquired cellular resistance against antifungal agents. Furthermore, selective pressure by antifungal drugs on yeast facilitated the de novo appearance of Mod5 prion states for cell survival. Thus, phenotypic changes caused by active prion conversion under environmental selection may contribute to cellular adaptation in living organisms.     

鄱阳湖湿地动态变化及其成因分析

洲滩是鄱阳湖区分布广泛、数量众多和最为活跃的景观要素之一。研究洲滩的结构及动态变化、洲滩对鄱阳湖功能的影响,对鄱阳湖的治理有着重要参考价值。论述鄱阳湖的自然地理概况、土地利用动态,并着重分析洲滩的动态变化及其成因。结果表明:湖区大量泥沙淤积造成的洲滩,在一定程度上影响了湖流形态、泥沙冲淤和江湖水文关系等。因此,洲滩的改变导致鄱阳湖调蓄功能、生态功能等的变化,其分布和动态是反映鄱阳湖演变规律的重要信息。     

Rational choice, context dependence, and the value of information in European starlings (Sturnus vulgaris)

Both human and nonhuman decision-makers can deviate from optimal choice by making context-dependent choices. Because ignoring context information can be beneficial, this is called a "less-is-more effect." The fact that organisms are so sensitive to the context is thus paradoxical and calls for the inclusion of an ecological perspective. In an experiment with starlings, adding cues that identified the context impaired performance in simultaneous prey choices but improved it in sequential prey encounters, in which subjects could reject opportunities in order to search instead in the background. Because sequential prey encounters are likely to be more frequent in nature, storing and using contextual information appears to be ecologically rational on balance by conditioning acceptance of each opportunity to the relative richness of the background, even if this causes context-dependent suboptimal preferences in (less-frequent) simultaneous choices. In ecologically relevant scenarios, more information seems to be more.     

Topological solutions in gauge theory and their computer graphic representation

A diverse range of physical phenomena, both observed and hypothetical, are described by topological solutions to nonlinear gauge field theories. Computer-generated color graphic displays can provide a clear and detailed representation of some of these solutions, which might otherwise be physically unintelligible because of their mathematical complexity. Graphical representations are presented here for two topological solutions: (i) the solutions of a model that represents the filaments of quantized magnetic flux in a superconductor, and (ii) the solutions of an SO(3) gauge theory corresponding to a pair of separated magnetic monopoles. An introduction is provided to the gauge field theories giving rise to these solutions.     

杂交玉米优良品种对比试验

通过选择目前广西已审定通过或已进入生产性试验的13个玉米新品种,以"正大619"品种为对照,在广西天等县进行品种对比试验,旨在鉴定参试品种的丰产性、适应性、抗逆性以及品质,客观评价参试品种特征特性及生产利用价值,为天等县玉米高产优质生产种植提供科学依据。试验结果表明,参试品种中,亚航0919、亚航639、南校969、桂单591、亚航689产量增幅较高在19.3%-36.44%之间,综合性状表现好,增产潜力大,可在天等县因地制宜推广种植;桂单0810、兆丰788、兆丰688虽与对照品种增产幅度不大,但在整齐度,综合性状表现优于对照品种,可因地制宜推广种植;桂单1125虽比对照品种产量增幅大,但后期早衰严重,表现一般;其他品种因田间表现不佳,建议不宜大面积推广种植。     

通辽地区总水资源动态模拟评价

文中提出了水资源的动态模拟评价观点及其系列评价方法和过程，认为，水资源不是一种静态, 而是一种动态资源，它随着人力干及周围环境的变化而变化，也就是说，水资源不但存在着时空变异性，而且是一种随时间，空间不断动态变化的资源，文中还提出了水资源的周期评价观点，即评价水资源时应以大周期作为评价时段，那种以任一时段间隔作评价期的作法是造成评价水资源偏大或偏小的重要原因，根据上述新观观点，我们论述了各项地下水资源，地表水资源有其地表水－地下水相互转化资源量的动态变化规律，并根据各项水资源的评价结果对它们进行了动态模拟评价。     

Normalization for sparse encoding of odors by a wide-field interneuron

Sparse coding presents practical advantages for sensory representations and memory storage. In the insect olfactory system, the representation of general odors is dense in the antennal lobes but sparse in the mushroom bodies, only one synapse downstream. In locusts, this transformation relies on the oscillatory structure of antennal lobe output, feed-forward inhibitory circuits, intrinsic properties of mushroom body neurons, and connectivity between antennal lobe and mushroom bodies. Here we show the existence of a normalizing negative-feedback loop within the mushroom body to maintain sparse output over a wide range of input conditions. This loop consists of an identifiable "giant" nonspiking inhibitory interneuron with ubiquitous connectivity and graded release properties.     

气候变化对西南大西洋渔业生态系统的影响研究进展

西南大西洋是世界重要的渔区之一，捕捞国家包括阿根廷等西南大西洋沿海国以及中国、日本等众多非沿海国家，其中阿根廷滑柔鱼（Illex argentinus）、阿根廷无须鳕（Merluccius hubbsi）、巴西小沙丁鱼（Sardinella brasiliensis）与弗氏绒须石首鱼（Micropogonias furnieri）是西南大西洋年均产量最高的4种主要经济渔获物。探究气候变化对西南大西洋生态系统的影响有利于建立基于生态系统的渔业资源保护与利用格局。本文从渔业资源与生态系统两个角度出发，分别归纳了生态系统的生物因子（主要经济渔获物）、非生物因子（环境因素）与营养结构（食物链和食物网）对气候变化的响应情况。分析认为，在今后探究西南大西洋生态系统对气候变化的响应的研究中，选取代表物种表征生态系统的变化并结合人类活动与气候变化的影响可以丰富生态系统的相关结论，为西南大西洋海域提供基于生态系统的科学管理策略。     

Transition States Between Pyramids and Domes During Ge/Si Island Growth

Real-time observations were made of the shape change from pyramids to domes during the growth of germanium-silicon islands on silicon (001). Small islands are pyramidal in shape, whereas larger islands are dome-shaped. During growth, the transition from pyramids to domes occurs through a series of asymmetric transition states with increasing numbers of highly inclined facets. Postgrowth annealing of pyramids results in a similar shape change process. The transition shapes are temperature dependent and transform reversibly to the final dome shape during cooling. These results are consistent with an anomalous coarsening model for island growth.     

基于NDVI和EVI不同植被指数表征的粤港澳大湾区植被空间格局驱动因子影响力比较分析

为研究归一化植被指数（normalized difference vegetation index,NDVI）和增强植被指数（enhanced vegetation index,EVI）的表征差异是否会造成有关植被研究的结果差异，分别在采用2005—2020年MODISNDVI、MODIS-EVI 2种不同遥感植被指数表征粤港澳大湾区植被空间特征的基础上，以同时期17个自然因子和人为因子作为驱动因子，通过地理探测器模型方法，计算各驱动因子对基于NDVI和EVI的植被空间特征的影响力。结果显示，虽然粤港澳大湾区南亚热带-热带植被在NDVI和EVI的表征下，其结果存在差异，但在不同植被指数下，通过地理探测器模型方法计算各驱动因子影响力量化及排序结果基本一致，未受不同植被指数表征差异的影响。在驱动因子中，土地利用类型、高程均是最主要驱动因子，对植被空间分布影响力均超过50%。因子之间均表现出双因子增强作用。土地利用类型协同人口分布因子对NDVI表征下的植被空间分布影响力最强；高程协同人口分布因子对EVI表征下的植被空间分布影响力最强。研究结果表明，虽然NDVI、EVI在表征植被覆盖特征方面存...