1,720,978 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
T-type 칼슘채널의 외측슬상핵 시상피질신경세포에서의 예측적 항상성 촉진에 대한 연구
No full text학위논문(박사) - 한국과학기술원 : 바이오및뇌공학과, 2015.2
,[v, 125 p :]예측정 항상성 이론은 모든 신경세포의 기능을 예측이라고 본다. 감각기관이 자신의 감수성을 유지하기 위하여 감각신호에 빠르게 적응한다는 것은 잘 알려져 있다. 본 연구의 예측적 항상성 이론은 동일한 기작을 세포수준에서 적용하여 신경세포가 넓은 범위의 감각신호에 대응하여 자신의 출력능력을 유지할 수 있다고 설명한다. 특히, 본 연구에서는 신경세포를 관찰자로 보고 신경세포의 스파이크 출력을 신경세포의 관점에서 해석하려고 하였다. 이러한 관점에서 단일신경세포의 스파이크 출력은 감각신호 입력에 대한 출력 확률을0.5로 유지할 때 신경세포의 정보량을 최대화 할 수 있다는 것을 보여준다. 신경세포의 스파이크 출력이 시냅스 입력에 대해 감수성을 유지하기 위해서는 세포막의 흥분성을 조절하기 위한 여러가지 항상성기전을 필요로 한다. 탈분극에 의해 활성화되는 칼륨이온채널이 음성피드백과 억제를 통해 항상성을 촉진한다는 사실은 잘 알려져 있지만, 본 연구에서는 T-type 칼슘이온채널이 양성피드백과 흥분을 통해서 또한 항상성을 촉진할 수 있다는 것을 보여준다. 본 연구에서는 쥐의 외측슬상핵 뇌절편의 시상피질 신경세포를 다이나믹 패치클램프 기법을 이용하여 시각적으로 유도된 자연적인 과분극을 흉내 내어 측정하였다. 과분극기간동안의 T-type 칼슘이온채널의 불비활성화는 망막슬상 시냅스의 시상피질 신경세포에 대한 흥분능력을 200 ms 에서 400 ms 사이에 스파이크를 유도할 만큼 회복시켰다. T-type 이온채널은 자연적이지 않은 상태에서 주로 발견되는 실무율에 의거한 버스트 스파이크의 생성을 촉진하기보다는 두 개의 입력에 대해 하나의 출력을 만들어내는 세포막의 항상적 흥분성을 유지하였다. 따라서 본 연구결과는 T-type 칼슘이온채널의 기능이 예측적 항상성 이론에 근거한 효율적인 정보처리 가설에 잘 부합될 수 있다는 결과를 보여주며, 자연적인 시냅스 입력패턴에 대한 정보에 따라 이온채널의 기능을 예측하고자 하는 일반이론을 지지한다.한국과학기술원 :바이오및뇌공학과
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
시상 감각핵과 운동핵의 버스트 발생에 대한 비교 연구
No full text학위논문(석사) - 한국과학기술원 : 바이오및뇌공학과, 2013.2, [ iv, 41 p. ]It is customary to distinguish between sensory neurons and motor neurons, and the distinction between the two is clear and useful when considering function within an intact nervous system. Input of sensory neurons is closely related with the stimuli from the environment. On the other hand, output of motor neurons is related with behavior. The whole nervous system uses information from sensory world to select output to generate behaviors. For achieving this general goal of nervous system, sensory neurons should discriminate new information from sensory stimuli, while motor neurons should select output for behavior. However, there is no known difference at the cellular or molecular levels.
We tested a hypothesis that there are cellular level differences between sensory and motor neurons. Efficient coding theory (Barlow, 1961) suggested that, a sensory neuron should predict its input and maintain homeostatic level of activity, so that neuron can only signal new information (prediction error). A lot of ex-perimental evidences support that this homeostatic mechanism is achieved in many sensory neurons by opening of specific kinds of ion channels and canceling redundant input. On the other hand, it is well known that some motor neurons tend to generate patterns by their intrinsic property. Our hypothesis is that sensory neurons maintain homeostatic excitability and decorrelate patterns, whereas motor neurons generate patterns.
To investigate the sensory and motor difference, we tested our hypothesis in thalamocortical (TC) re-lay neurons, and particularly the function of low voltage activated t-type calcium channels. We recorded neurons in rat brain slices of lateral geniculate nucleus (LGN, sensory nucleus), and ventrolateral nucleus (VL, motor nucleus) using whole cell patch clamp technique.
In TC neurons of both LGN and VL, depolarization from low voltage (-80 and -90 mV) activated T-type calcium current and generated a low threshold spike (LTS). In VL neurons,...한국과학기술원 : 바이오및뇌공학과
쥐의 도파민 뉴런에 대한 광유전학 조절을 통한 조작적 강화
No full text학위논문(박사) - 한국과학기술원 : 바이오및뇌공학과, 2012.8, [ iii, 52 p. ]Activation of dopamine receptors in forebrain regions, for minutes or longer, is known to be sufficient for positive reinforcement of stimuli and actions. However, the firing rate of dopamine neurons is increased for only about 200 milliseconds following natural re-ward events that are better than expected, a response which has been described as a “reward prediction error” (RPE). Although RPE drives reinforcement learning (RL) in computational models, it has not been possible to directly test whether the transient dopamine signal actually drives RL. Here we have performed optical stimulation of genetically targeted ventral tegmental area (VTA) dopamine neurons expressing Channelrhodopsin-2 (ChR2) in mice. We mimicked the transient activation of dopamine neurons that occurs in response to natural reward by applying a light pulse of 200 ms in VTA. When a single light pulse followed each self-initiated nose poke, it was sufficient in itself to cause operant reinforcement. Furthermore, when optical stimulation was delivered in separate sessions according to a predetermined pattern, it increased locomotion and contralateral rotations, behaviors that are known to result from activation of dopamine neurons. All three of the optically induced operant and locomotor behaviors were tightly correlated with the number of VTA dopamine neurons that expressed ChR2, providing additional evidence that the behavioral responses were caused by activation of dopamine neurons. These results provide strong evidence that the transient activation of dopamine neurons provides a functional reward signal that drives learning, in support of RL theories of dopamine function.한국과학기술원 : 바이오및뇌공학과
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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