Time-dependent processes in memory storage

These observations indicate that the long-lasting trace of an experience is not completely fixed, consolidated, or coded at the time of the experience. Consolidation requires time, and under at least some circumstances the processes of consolidation appear to be susceptible to a variety of influences- both facilitating and impairing- several hours after the experience. There must be, it seems, more than one kind of memory trace process (31). If permanent memory traces consolidate slowly over time, then other processes must provide a temporary basis for memory while consolidation is occurring. The evidence clearly indicates that trial-to-trial improvement, or learning, in animals cannot be based completely on permanent memory storage. Amnesia can be produced by electroshock and drugs even if the animals are given the treatment long after they have demonstrated "learning" of the task. Of particular interest is the finding that retention of the inhibitory avoidance response increases with time. In a sense this should be expected, for it has long been known (and ignored) that, within limits, learning is facilitated by increasing the interval between repeated trials (7, 30). Our result may be the simplest case of such an effect. Since the improvement in retention with time seemed not to be due solely to consolidation (as indicated by electroshock effects), it would seem that the "distribution of practice" effect, as it is typically designated, may be due in part to a time-dependent temporary memory storage process. In our work with animals we have found no analog of human immediate memory such as that required for repeating digits (or finishing sentences). Animals tested immediately on the task described above after a trial typically showed no evidence of memory. It could be that the poor performance is due to excessive fright, but the "distribution of practice effect" is also typically observed in learning experiments in which food reward is used rather than shock avoidance. Since the retention tasks require the animals to change their behavior in some way, it could well be that the growth of retention over the first few minutes after a trial is due to time dependent processes involved in the organization of processes necessary for changing behavior, in addition to those involved in temporary storage and retrieval. It is worth pointing out that there is evidence of an analogous process in human memory (32). A complex picture of memory storage is emerging. There may be three memory trace systems: one for immediate memory (and not studied in our laboratory); one for short-term memory which develops within a few seconds or minutes and lasts for several hours; and one which consolidates slowly and is relatively permanent. The nature of the durability of the longterm memory trace (that is, the nature and basis of forgetting) is a separate but important issue. There is increasing evidence and speculation (20, 21, 33) that memory storage requires a "tritrace" system, and our findings are at least consistent with such a view. If there are, as seems possible, at least three kinds of traces involved in memory storage, how are they related? Is permanent memory produced by activity of temporary traces (31), or are the trace systems relatively independent? Although available findings do not provide an answer to this question, there does seem to be increasing evidence that the systems are independent. Acquisition can occur, as we have seen, without permanent consolidation, and both short-term and long-term memory increase with time. All this evidence suggests (but obviously does not prove) that each experience triggers activity in each memory system. Each repeated training trial may, according to this view, potentiate short-term processes underlying acquisition while simultaneously enhancing independent underlying long-term consolidation. Obviously, acceptance of these conclusions will require additional research. If this view is substantially correct, it seems clear that any search for the engram or the basis of memory is not going to be successful. Recognition of the possibility that several independent processes may be involved at different stages of memory may help to organize the search. A careful examination of the time course of retention and memory trace consolidation, as well as examination of the bases of the effects of memory-impairing and memory-facilitating treatments, may help to guide the search. It is clear that a complete theory of memory storage must eventually provide an understanding of time-dependent processes in memory. In 1930 Lashley wrote (2), "The facts of both psychology and neurology show a degree of plasticity, of organization, and of adaptation and behavior which is far beyond any present possibility of explanation." Although this conclusion is still valid, the current surge of interest in memory storage offers hope that this conclusion may soon need to be modified.     

Three-dimensional super-resolution imaging by stochastic optical reconstruction microscopy

Recent advances in far-field fluorescence microscopy have led to substantial improvements in image resolution, achieving a near-molecular resolution of 20 to 30 nanometers in the two lateral dimensions. Three-dimensional (3D) nanoscale-resolution imaging, however, remains a challenge. We demonstrated 3D stochastic optical reconstruction microscopy (STORM) by using optical astigmatism to determine both axial and lateral positions of individual fluorophores with nanometer accuracy. Iterative, stochastic activation of photoswitchable probes enables high-precision 3D localization of each probe, and thus the construction of a 3D image, without scanning the sample. Using this approach, we achieved an image resolution of 20 to 30 nanometers in the lateral dimensions and 50 to 60 nanometers in the axial dimension. This development allowed us to resolve the 3D morphology of nanoscopic cellular structures.     

Puromycin effect on successive phases of memory storage

Mice injected bitemporally with puromycin 5 hours before training learned to escape or to avoid shock by choosing the correct limb of a Y-maze. When retested 15 minutes after training they had normal retention. In the ensuing 2(3/4) hours the animals injected with puromycin, unlike the controls, showed a progressive decrease of savings to less than 7 percent.     

苹果贮藏中水心消失速率的研究

利用可见-近红外光谱和X射线成像技术研究了水心苹果贮藏中水心消失速率.采用PLSDA和平均灰度值法对水心判别,研究120水心苹果贮藏中的光谱及灰度图像的变化规律.结果表明:PLSDA和平均灰度值法对水心判别,判别正确率分别为96.7%和97.43%;水心消失速率在贮藏前期高于贮藏后期;水心苹果平均光谱峰面积与贮藏时间拟合方程为:y=-0.0002x3 0.0733x2-7.405x 342.06;该实验条件下,近红外平均能量谱峰面积和X射线图像平均灰度值的贮藏临界值分别为110.21,143.91.实验结果表明可见-近红外能量光谱和X射线成像技术可以快速、无损、准确鉴别苹果水心及检测贮藏变化规律.     

Theta rhythm: a temporal correlate of memory storage processes in the rat

We examined the amount of theta rhythm (4 to 9 hertz) in cortical electroencephalograms of rats for 30 minutes after training in one-trial tasks. Some animals received electroconvulsive shock after training. The amount of theta in the electroencephalogram after training was positively correlated with the degree of subsequent retention of a footshock, whether animals had received electroconvulsive shock or not.     

The primate hippocampal formation: evidence for a time-limited role in memory storage

Clinical and experimental studies have shown that the hippocampal formation and related structures in the medial temporal lobe are important for learning and memory. Retrograde amnesia was studied prospectively in monkeys to understand the contribution of the hippocampal formation to memory function. Monkeys learned to discriminate 100 pairs of objects beginning 16, 12, 8, 4, and 2 weeks before the hippocampal formation was removed (20 different pairs at each time period). Two weeks after surgery, memory was assessed by presenting each of the 100 object pairs again for a single-choice trial. Normal monkeys exhibited forgetting; that is, they remembered recently learned objects better than objects learned many weeks earlier. Monkeys with hippocampal damage were severely impaired at remembering recently learned objects. In addition, they remembered objects learned long ago as well as normal monkeys did and significantly better than they remembered objects learned recently. These results show that the hippocampal formation is required for memory storage for only a limited period of time after learning. As time passes, its role in memory diminishes, and a more permanent memory gradually develops independently of the hippocampal formation, probably in neocortex.     

单板层积材的三维光学检测及其托盘的有限元仿真分析

目的单板层积材应用广泛,但其性能测试多采用破坏性实验方法,存在检测效率低且会造成资源浪费的不足。本研究对一种新型层积板材及其制得的托盘进行无损检测,旨在为木质层积材及制品性能的高效、精确检测提供理论参考和技术支撑。方法将三维光学检测法与有限元仿真分析相结合,首先采用数字散斑法测量并计算获得新型层积板材的弹性常数（包括弹性模量,泊松比,剪切模量）;然后导入有限元仿真分析中,分别选取layer单元和solid 185单元对板材模型进行网格划分和静力模拟,优化其仿真模拟参数;参照国际标准ISO 8611—2011 对新型层积板材托盘性能进行检测,利用Solidworks建立及装配托盘模型,在ANSYS workbench软件中对托盘整体结构进行整体抗压、底板抗压、面板抗压和角跌落等仿真模拟,并与实验测试结果进行对比分析。结果三维光学法获得的弹性参数可以应用于新型层积板材及其制品的有限元仿真分析中,ANSYS有限元仿真结果可靠;将新型层积材作为整体结构,选用solid 185单元的仿真模拟结果与实际测试情况最为接近;新型层积材托盘静力仿真分析中托盘的最大变形与实验结果相近,4种工况仿真分析结果与实测结果相同。结论三维光学检测法结合有限元仿真分析可以对木质层积材及其制品的受力、变形和破坏情况进行无损检测,可达到高效和节能的目的。      

Electronic spin storage in an electrically readable nuclear spin memory with a lifetime >100 seconds

Electron spins are strong candidates with which to implement spintronics because they are both mobile and able to be manipulated. The relatively short lifetimes of electron spins, however, present a problem for the long-term storage of spin information. We demonstrated an ensemble nuclear spin memory in phosphorous-doped silicon, which can be read out electrically and has a lifetime exceeding 100 seconds. The electronic spin information can be mapped onto and stored in the nuclear spin of the phosphorus donors, and the nuclear spins can then be repetitively read out electrically for time periods that exceed the electron spin lifetime. We discuss how this memory can be used in conjunction with other silicon spintronic devices.     

光纤技术在盐穴储气库油水界面监测中的应用

盐穴储气库腔体形态控制是制约储气库库容和实现储气库稳定运行的重要因素,控制阻溶剂界面位置是控制腔体形态的关键。为了改进现有控制方法监控成本高、不能实时测量等缺点,提出光纤式界面监测方法:使用新型光纤界面测试仪进行测量,利用分布式光纤测试技术,通过光缆中的电缆加热,由于卤水和垫层介质(一般用柴油、氮气)的比热容不同,光缆与周围介质进行热交换发生温度变化,根据温差即可判断介质界面位置。基于光纤式界面监测方法,研制了新型的分布式光纤界面测试仪,其具有操作简单、探测范围广、监测成本低、实时测量井下介质界面的优点。利用该技术可实现盐穴储气库的大规模反循环造腔,加快造腔速度,保障腔体安全。(图5,表1,参24)     

Three-dimensional map construction

Three-dimensional maps are useful tools which have been neglected for some time. They shouldbe more commonly used, and familiarity with the techniques discussed in this article should dispel any qualms anyone might ve about needing artistic talent to nstruct them. The saving in time esulting from the use of an anamorphoser provides a further incentive. The anamorphoser transformations discussed above were all prepared by using straight slits, oriented at right angles to each other and placed so that all planes of the elements were parallel to each other. It is possible to vary these conditions in an infinite number of ways and thereby produce nonparallel tranceformations. Some of these variations are illustrated in Fig. 10. All the illustrations in Fig. 10 are transformations of the planimetric weather map shown in Fig. 8A. The variations used for the maps of Fig. 10 are as follows. (A) All planes parallel, with a curved rear slit; (B) all planes parallel, with curved slits front and rear; ( C) all planes parallel, with S-shaped rear slit; (D) all planes parallel, with an undulating rear slit; (E) all planes parallel, with curved front and undulating rear slit; (F) plane of the original rotated on the horizontal axis-both slits curved; (G) plane of the original rotated on thevertical axis- both slits curved; (H) plane of the original rotated on the horizontal axis -both slits straight. These are only a few of the many transformations which can be made with an anamorphoser, butthey do point toward some interesting possibilities. For example, it appears that maps based onone projection might be altered to satisfy the coordinates of a completely different projection. Note, for example, the change of parallels from concave to convex curves (Figs. 8A and 10A) and the change from converging meridians to diverging meridians (Figs. 8A and l0G). Similarly, the grids of maps B, F, and H of Fig. 10 approximate projections which are quite different from the original. Other possible, and noncartographic, uses also come to mind. For example, transformations offront and side views of architectural and engineering drawings could be made to show views fromdifferent elevations and orientations. Or a geologist might be able to illustrate folding of sedimentary strata by preparing a drawing of a series of horizontal beds and then using an anamo-rephoser with an undulating slit to alter the beds to any degree of folding desired. With a movie camera and a moving lens mount this "folding" process could be photographed with different settings, so that the parallel beds would gradually and continuously change to irregularly folded beds. The transformations shown in Fig. 10 resulted from uncontrolled experimentation with the anamorphoser, and as yet no geometric solutions for setting up the transformation elements are available. Similarly, the suggested uses are mere flights of fancy, and no claim is made for theirpracticality. It is hoped, however, that they will stimulate the reader's imagination and lead him to look for uses of the anamorphoser in fields other than cartography (9).     

Three-dimensional plasmon rulers

Plasmon rulers can be used to determine nanoscale distances within chemical or biological species. They are based on the spectral shift of the scattering spectrum when two plasmonic nanoparticles approach one another. However, the one-dimensionality of current plasmon rulers hampers the comprehensive understanding of many intriguing processes in soft matter, which take place in three dimensions. We demonstrated a three-dimensional plasmon ruler that is based on coupled plasmonic oligomers in combination with high-resolution plasmon spectroscopy. This enables retrieval of the complete spatial configuration of complex macromolecular and biological processes as well as their dynamic evolution.     

生菜立体水培技术

生菜立体化的无土栽培即立柱栽培,是在不影响平面栽培情况下,充分利用温室空间和太阳能,通过竖立起来的柱形栽培向空间发展,可提高土地利用率3～5倍,提高单位面积产量2～3倍,同时也提高了设施利用率,立柱栽培有基质培和水培两种形式,着重介绍了立体水培技术。     

三维旅游场景可视化研究

首先建立DEM模型、地物模型、建筑物模型等要素,然后将各要素叠加建立三维旅游场景,再对该场景模型进行缓冲分析、场景自动旋转、沿路线旅游、录制视频等操作,从而达到虚拟旅游的效果。系统运行结果表明该场景效果逼真,运行速度较快,基本可以满足游客需求。