Hum-controlled electric wheelchair

The authors described in an earlier paper a versatile electronic control system for wheelchairs. This paper describes a plug-in conversion to the original controller so that high-level quadriplegics (c4 and above) can completely control a wheelchair by humming four notes of the musical scale. Forward-stop-reverse, right-turn and left-turn functions are provided through the use of tone decoders. The control system is designed so that the frequencies to which it respons are easily adjustable to match users' vocal characteristics.     

Precision measurement of electric organ discharge timing from freely moving weakly electric fish

Physiological measurements from an unrestrained, untethered, and freely moving animal permit analyses of neural states correlated to naturalistic behaviors of interest. Precise and reliable remote measurements remain technically challenging due to animal movement, which perturbs the relative geometries between the animal and sensors. Pulse-type electric fish generate a train of discrete and stereotyped electric organ discharges (EOD) to sense their surroundings actively, and rapid modulation of the discharge rate occurs while free swimming in Gymnotus sp. The modulation of EOD rates is a useful indicator of the fish's central state such as resting, alertness, and learning associated with exploration. However, the EOD pulse waveforms remotely observed at a pair of dipole electrodes continuously vary as the fish swims relative to the electrodes, which biases the judgment of the actual pulse timing. To measure the EOD pulse timing more accurately, reliably, and noninvasively from a free-swimming fish, we propose a novel method based on the principles of waveform reshaping and spatial averaging. Our method is implemented using envelope extraction and multichannel summation, which is more precise and reliable compared with other widely used threshold- or peak-based methods according to the tests performed under various source-detector geometries. Using the same method, we constructed a real-time electronic pulse detector performing an additional online pulse discrimination routine to enhance further the detection reliability. Our stand-alone pulse detector performed with high temporal precision (<10 μs) and reliability (error <1 per 10(6) pulses) and permits longer recording duration by storing only event time stamps (4 bytes/pulse).     

卡维地洛对麻醉兔希氏束电活动和心电活动的影响

目的：研究卡维地洛对麻醉兔希氏束电活动和心电活动的影响。方法：采用左心导管法记录IIBE,同步记录Ⅱ导联ECG,并与普萘洛尔进行比较。结果：卡维地洛在0．01,0.11,3,6,9mg·kg－1时分别减慢HR（%）：9．1±4．8,21．3±3．0,30．7±4．0,35.4±5．6,40．0±6．0,42．5±6.1;延长P－R间期（％）：1．8±3．0,5．4±4．9,10．0±7．4,16.8±8．4,25．7±9．3,33．6±12．4;延长A－H间或（％）：5．6±4．8,10．9±6．4,16．5±6．2,24．2±7．7,31．6±10．8,20．6±15．0延长H－V间期（％）：5．1±5．4,8．7±5．3,14．9±5．7,21．2±9．5,27．1±11．2,39．9±9．4增宽Ⅴ波（%）：2．0±42,3．8±3．9,7．8±7．1,15．6±11．0,37．0,37．0±2．4。结论：在同一累积剂量,卡维地治和普菲洛尔对心脏的抑制作用基本相同,卡维地洛可能比普蒂洛尔更适合治疗心血管系统疾病。但对已有心动过缓和心脏传导阻滞的患者,临床应用时仍应注意卡维地洛的心脏抑制作用。     

Circadian rhythms in electric waveform structure and rate in the electric fish Brachyhypopomus pinnicaudatus

Weakly electric fish have long been known to express day-night oscillations in their discharge rates, and in the amplitude and duration of individual electric organ discharges (EODs). Because these oscillations are altered by social environment and neuroendocrine interactions, electric fish are excellent organisms for exploring the social and neuroendocrine regulation of circadian rhythm expression. Previous studies asserting that these oscillations are circadian rhythms have been criticized for failing to control temperature and randomize feeding regimes, or for running the fish under constant conditions for just 2-3 days. Here we show that the day-night oscillations in the EODs of the neotropical gymnotiform fish Brachyhypopomus pinnicaudatus free-run for over a week under constant photic and thermal conditions, and randomized food provisioning. Sex differences were apparent in strength and magnitude of the circadian oscillations; male oscillations were stronger and larger. All three parameters retain a common oscillation period while differing in the persistence of oscillation strength and magnitude, a difference consistent with proposals by others that declines of behavioral circadian rhythms may result from breakdowns downstream of the central oscillator.     

电场对红细胞沉降率的影响Ⅵ——电场方式依赖性

利用自行研制的红细胞流变参数自动测试分析仪及显微形态观测法，研究了三种电场方式对红细胞在生理盐水溶液中及在自体血浆中沉降及聚集特性的影响。结果表明，交流电场能使悬浮于生理盐水溶液中的红细胞产生轻度聚集，沉降过程加快。直流恒流电场不能 于一时卤水中的红细胞发生聚集，其沉降过程加快仅电场力作用所致。直流恒压电场 下红细胞在生理直 的沉降曲线为指数形，但这种指数形曲线与红细胞聚集无在，而是回路中电流随时     

Tetrodotoxin-resistant electric activity in presynaptic terminals

1. The electric properties of the giant synapse in the stellate ganglion of the squid have been further investigated.2. During tetrodotoxin (TTX) paralysis, a local response can be elicited from the terminal parts of the presynaptic axons after intracellular injection of tetraethyl ammonium ions (TEA).3. The response is characterized by an action potential of variable size and duration, whose fall is often preceded by a prolonged plateau. The response, especially the duration of the plateau, is subject to ;fatigue' during repetitive stimulation.4. The TTX-resistant form of activity is localized in the region of the synaptic contacts, and shows a marked electrotonic decrement even within less than 1 mm from the synapse. It is found only on the afferent, not on the efferent, side of the synapse.5. During the plateau of the response, the membrane resistance is greatly reduced below its resting value.6. The response depends on presence of external calcium and increases in size and duration with the calcium concentration. Strontium and barium substitute effectively for calcium. Manganese and, to a lesser extent, magnesium, counteract calcium and reduce the response. The response also declines, and ultimately disappears, if sodium is withdrawn for long periods.7. The relation of the local TTX-resistant response to the influx of calcium ions and to the release of the synaptic transmitter is discussed.     

On the use of electric and magnetic data to determine electric sources in a volume conductor

Methods of obtaining detailed information about electrical sources in semi-infinite and spherical volume conductors using electric and magnetic surface data are investigated. Surface data produced by various actual sources in the conductors are calculated. Using these data, a least-squares error (LSE) solution is then obtained for the dipoles in a multiple dipole assumed source and a comparison of the actual and assumed sources is made. Noise is simulated by the addition of random numbers to the data; modeling errors by the use of actual and assumed sources with different configurations. It is found that it is not possible to calculate a condition number (CN) which serves as a useful measure of the sensitivity of the LSE solutions to noise and modeling errors. It is also found that no useful information about the actual source can be obtained from LSE solutions when noise and modeling errors are present. No improvement is obtained when magnetic or a combination of electric and magnetic data are used. However, it is found that three additional solutions developed from the LSE solutions can provide some accurate information. These three solutions provide information about the general magnitude and orientation of the electrical activity of the actual source as well as the “flow” and “rotation” characteristics of the source. The most accurate flow information tends to be produced by electric or a combination of electric and magnetic data; the most accurate rotation information tends to be produced by magnetic or a combination of data. This indicates that electric and magnetic measurements can provide different information when noise and modeling errors are present. The results also show that information about the location of the actual source is provided by a comparison of differences between actual surface data and that produced by a series of LSE solutions. There are no improvements in the location information when a combination of data is used. Work supported by Public Health Service Research Fellowship (National Heart, Lung, and Blood Institute) No. 1 F32 HL05419.     

An electric tooth pulp vitality tester

A simple battery-powered constant-current pulse generator able to supply up to 200 μA at a maximum of 250 V is described. The tester incorporates a battery status indicator and an overload, incorrect operation and fault condition audible alarm. A simple test routine helps to ensure that the instrument is operating correctly before each application. For enhanced patient co-operation and comfort the tester is activated by the patient.     

Engineering manual and electric powered wheelchairs

The sophistication required to develop and properly configure a wheelchair is illustrated by the amount and complexity of the research being conducted. At this time there appears to be between 1.5 and 2.0 million full-time wheelchair users within the United States. The reliance of the user on the wheelchair and the amount of time in the wheelchair provide significant challenges for the wheelchair design engineer. Currently there are a wide variety of wheelchair designs that are commercially available. These wheelchairs accommodate a variety of people's needs, and represent significant progress. The current trend among manufacturers of manual wheelchairs seems to be cost-reduction engineering. The ergonomics of long-term wheelchair use are critical to the advancement of wheelchair design and to the clinical selection of wheelchairs. Electric powered wheelchairs appear to be progressing faster than nearly all other types of wheelchairs. This is due to the availability of computing power with low cost microcontrollers and associated peripherals. The greater range and availability of sensors are also making changes into the design of electric powered wheelchairs. The interaction between an electric powered wheelchair and the user can be extremely complex. In many cases, individual solutions are necessary. One of the more challenging questions is determining the abilities of the user required to drive an electric powered wheelchair effectively. There have been substantial improvements in the engineering of all wheelchairs. However, there remain significant issues to be addressed.     

生物信息学电子文档收编及优化检索的实现

生物信息学涉及生物、化学、物理、数学、计算机和互联网应用等多方面知识,要从事这个领域的研究工作,必须掌握更多的各方面知识.目前该领域的很多资料和文献在网上以电子文档的形式存在.电子文档能够包含比常规的文档包含更广泛,更丰富的内容,对电子文档的收编整理能大大节省文档的搜索时间,并能提供更专业,更有效的检索结果,为科研工作服务.本文论述了建立包括电子文档的收集,标注,优化检索的一个方案,检索结果按照文档和检索条件的相似程度分级列出.实践证明,该系统能够有效的提供生物信息学专业信息的管理和检索.     

Microbiological implications of electric field effects III. Stimulation of yeast protoplast fusion by electric field pulses

Prototrophic colonies could be selected on minimal medium after mixing of protoplasts from diauxotrophic mutants of the yeasts Saccharomycopsis lipolytica and/or Lodderomyces elongisporus and treatment with polyethylene glycol (PEG) in the presence of calcium chloride. This is the result of protoplast fusion and complementation of auxotrophic deficiencies. Under identical conditions an electric field pulse in the μs-range applied via an electric discharge to the protoplast-PEG mixture resulted in a drastic enhancement of the protoplast fusion rate. The presence of polyethylene glycol was demonstrated to be a prerequisite for fusion in this case, too. The frequency of hybrid formation detected as prototrophic colonies could be increased in the case of intraspecific fusion at initial electric field strengths between 2.5 and 5 kV · cm^?1. The application of an electric field pulse of proper strength and duration to a yeast protoplast suspension turned out to be a more effective tool in production of fusion products than conventional methods. Large numbers of parasexual hybrids for different selection programmes in yeast genetics and for industrial purpose may be delivered by this technique.