Depolarization-activated potentiation of the T fiber synapse in the blue crab

The blue crab T fiber synapse, associated with the stretch receptor of the swimming leg, has a nonspiking presynaptic element that mediates tonic transmission. This synapse was isolated and a voltage clamp circuit was used to control the membrane potential at the release sites. The dependence of transmitter release on extracellular calcium, [Ca]o, was studied over a range of 2.5-40 mM. A power relationship of 2.7 was obtained between excitatory postsynaptic potential (EPSP) rate of rise and [Ca]o. Brief presynaptic depolarizing steps, 5-10 ms, presented at 0.5 Hz activated EPSP's of constant amplitude. Inserting a 300-ms pulse (conditioning pulse) between these test pulses potentiated the subsequent test EPSPs. This depolarization-activated potentiation (DAP) lasted for 10-20 s and decayed with a single exponential time course. The decay time course remained invariant with test pulse frequencies ranging from 0.11 to 1.1 Hz. The magnitude and decay time course of DAP were independent of the test pulse amplitudes. The magnitude of DAP was a function of conditioning pulse amplitudes. Large conditioning pulses activated large potentiations, whereas the decay time constants were not changed. The DAP is a Ca-dependent process. When the amplitude of conditioning pulses approached the Ca equilibrium potential, the magnitude of potentiation decreased. Repeated application of conditioning pulses, at 2-s intervals, did not produce additional potentiation beyond the level activated by the first conditioning pulse. Comparison of the conditioning EPSP waveforms activated repetitively indicated that potentiation lasted transiently, 100 ms, during a prolonged release. Possible mechanisms of the potentiation are discussed in light of these new findings.The blue crab T fiber synapse, associated with the stretch receptor of the swimming leg, has a nonspiking presynaptic element that mediates tonic transmission. This synapse was isolated and a voltage clamp circuit was used to control the membrane potential at the release sites. The dependence of transmitter release on extracellular calcium, [Ca]o, was studied over a range of 2.5-40 mM. A power relationship of 2.7 was obtained between excitatory postsynaptic potential (EPSP) rate of rise and [Ca]o. Brief presynaptic depolarizing steps, 5-10 ms, presented at 0.5 Hz activated EPSP's of constant amplitude. Inserting a 300-ms pulse (conditioning pulse) between these test pulses potentiated the subsequent test EPSPs. This depolarization-activated potentiation (DAP) lasted for 10-20 s and decayed with a single exponential time course. The decay time course remained invariant with test pulse frequencies ranging from 0.11 to 1.1 Hz. The magnitude and decay time course of DAP were independent of the test pulse amplitudes. The magnitude of DAP was a function of conditioning pulse amplitudes. Large conditioning pulses activated large potentiations, whereas the decay time constants were not changed. The DAP is a Ca-dependent process. When the amplitude of conditioning pulses approached the Ca equilibrium potential, the magnitude of potentiation decreased. Repeated application of conditioning pulses, at 2-s intervals, did not produce additional potentiation beyond the level activated by the first conditioning pulse. Comparison of the conditioning EPSP waveforms activated repetitively indicated that potentiation lasted transiently, 100 ms, during a prolonged release. Possible mechanisms of the potentiation are discussed in light of these new findings.NS-07942 - NINDS NIH HHS; NS-13742 - NINDS NIH HH

Temperature and density measurements in the base region of a clustered rocket model using an electron beam technique

Temperature and density measurements in base region flow field of clustered rocket engine model using electron beam techniqu

Emotion and explanation

It is suggested that not only psychologists and physiologists, but also philosophers, have created confusion in their various approaches to the study of emotion by seeking to isolate and describe one feature of emotion and to label this as the “essence” or “basis” of emotion. Further, philosophers have concealed many important complexities by employing in their investigations of the concept the method of analysis 'by standard cases'. The main contention of this essay, on the other hand, is that emotion words are employed to signify phenomena so various that it is unrealistic to seek a description which would cover all cases of emotion and hence provide an answer to the question 'What is emotion? To show why this is so, our uses of emotion words to refer to 'feelings', emotional states, moods, impulse and dispositional motives and character traits are here examined, and the differences in their relationships to the concepts of wanting and of thinking are considered. Moreover, since it is held that emotion words serve not only as descriptive and evaluative terms, but are also frequently employed to provide explanations of behaviour, the various ways in which the uses of these words serve to make behaviour intelligible to us are examined. Basic to this investigation is the belief that in this area, as in all those generally specified as belonging to the Philosophy of Mind, philosophical analysis conducted in ignorance of, or disregard for, the empirical findings of psychology and physiology is frequently seriously misleading. For this reason, an attempt has here been made to ensure that the upholding of particular philosophical positions has not involved conflict with established empirical findings

Análisis del ciberataque para la seguridad de los estados y su incidencia en la transformación del status quo: Stuxnet el virus informático

La presente investigación realiza un análisis del caso Stuxnet, las implicaciones en seguridad que trae consigo el uso del ciberataque como un medio para alterar o cambiar las relaciones de poder entre los Estados. Se examina bajo la teoría del realismo estructuralista de Kenneth Waltz, el cual expone acerca de las dinámicas al interior de la estructura del sistema internacional y los constreñimientos que están sujetos a ella. Los Estados están interesados principalmente en su seguridad con el objetivo de sobrevivir y ello puede dirigir sus intereses para generar acciones que lo sostengan y aminore el riesgo o amenaza. El ciberataque Stuxnet responde a esta teoría como un medio por parte de Israel para deteriorar las capacidades nucleares de Irán, y reducir su rol en las relaciones de poder tanto en la región como en el ámbito internacional, además de contribuir a su propia supervivencia dependiente en el ámbito de la seguridad.The following investigation performs an insight of the Virus Stuxnet and its implications on security that follow with its use, as a means to alter or change the power relations between states. This is done using the theory of Structural Realism from Kenneth Waltz, which talks about the dynamics inside the international system and its constraints that are subject to it. States are interested primarily in their safety with the porpoise of survival and that may direct the rest of its interests upon actions to sustain it and lower the risk or threat. The Ciberattack of Stuxnet responds to this theory as a means by Israel to impair the nuclear capabilities of Iran, and reduce its role on the power relations both in the region and in the international atmosphere, as well contribute to its own survival dependent in the field of securityVICENTRE TORRIJOS, FACULTAD DE RELACIONES INTERNACIONALES UNIVERSIDAD DEL ROSARI

Respuesta a incidentes de seguridad

Peer Reviewe

The role of high-performance people management practices in Industry 4.0: the case of medium-sized Spanish firms

Purpose: This paper wants to build the case for the key role of high-performance people management practices in the development of I4.0 in SMEs. The research upon which this paper is based wants to prove that the consolidation of those practices should be a priority for any company willing to embark in this journey. The paper deals specifically with medium-sized Spanish firms which, on top, are already having significant issues with digitization. Design/methodology/approach: The paper starts by digging into the literature to see how past technologies have impacted productivity, followed by a review of the material available on digitization and Industry 4.0. It moves on to explore the relationship between people management practices, productivity and innovation. Finally, the focus is placed on Spanish medium-sized companies, understanding their current levels of consolidation of high-performance people management practices as well as digitization. With all this information, several propositions are posited for validation using the Delphi methodology. Findings: I4.0 is, at its core, about productivity improvements through business process and business model innovation. People management practices are found to be strongly correlated with both productivity and innovation. It has also been found that Spanish medium-sized firms already have a significant initial gap compared to those of other OECD countries not only in productivity, but also people management practices and digitization. The experts seem to agree on the key role of people management practices and that they should be a high priority for any firm seriously thinking about industry 4.0. This is not to say that strategy or leadership will not play a paramount role in any digital transformation, but to emphasize the fact that the normally-forgotten people management practices will be important enablers in this process. Originality/value: It is believed that this is a topic that has been mostly neglected in the I4.0 literature. In that sense, the findings of this paper could be relevant for small and medium-sized businesses embarking on the industry 4.0 journey. This will entail a significant investment of time and money and, if the key role of people management practices is not on the radar screen, it may have significant implications for the success of those ventures.Peer Reviewe