A presente tese descreve a construção de uma nova transformada wavelet, aqui chamada de SPIKELET, que, combinada com um algoritmo proposto, é aplicada no reconhecimento computacional de padrões em spikes (picos) e spikes sobrepostos (overlaps) encontrados no sinal digitalizado correspondente às reações do neurônio H1 do cérebro de uma mosca de ordem Diptera, que é sensível aos estímulos visuais do meio externo. O algoritmo fornece, além do formato do sinal encontrado, o \'\'instante\'\' em que ele ocorreu, sendo que a implementação é feita, inclusive, em tempo-real, com o uso de um DSP. / This thesis describes the construction of a new wavelet transform, that is called SPIKELET, which is used together with a proposed algorithm, for spikes and overlaps pattern recognition, in a digitalized signal corresponding to the H1 visual neuron action potential from a Diptera\'s fly brain. The algorithm provides both the shape of the identified signal and the \'\'instant\'\' of time it happened. The implementation is also done in real time, using a DSP.

A presente tese descreve a construção de uma nova transformada wavelet, aqui chamada de SPIKELET, que, combinada com um algoritmo proposto, é aplicada no reconhecimento computacional de padrões em spikes (picos) e spikes sobrepostos (overlaps) encontrados no sinal digitalizado correspondente às reações do neurônio H1 do cérebro de uma mosca de ordem Diptera, que é sensível aos estímulos visuais do meio externo. O algoritmo fornece, além do formato do sinal encontrado, o \'\'instante\'\' em que ele ocorreu, sendo que a implementação é feita, inclusive, em tempo-real, com o uso de um DSP. / This thesis describes the construction of a new wavelet transform, that is called SPIKELET, which is used together with a proposed algorithm, for spikes and overlaps pattern recognition, in a digitalized signal corresponding to the H1 visual neuron action potential from a Diptera\'s fly brain. The algorithm provides both the shape of the identified signal and the \'\'instant\'\' of time it happened. The implementation is also done in real time, using a DSP.

Spike Milligan has had an undisputable influence on English-language comedy in the past half-century. Monty Python’s Terry Jones cites the “free-wheeling fantasy world” Milligan created for the surreal radio series The Goon Show as the chief inspiration for his own group’s more internationally-famous work. However, Milligan’s writing for The Goon Show, which first aired between 1951 and 1960 displays a depth beyond “the confidence to be silly” noted by Python’s Michael Palin. Milligan’s scripts reveal a deliberate, if not wholly conscious, rejection of the laws of causality and probability, through frequent and systematic distortions of time and space. The fictional world revealed in The Goon Show’s corpus of half-hour stories is one in which concepts relating to time and space lack the fixed meanings that we attach to them in everyday life. Temporal and spatial relationships are fluid and indeterminate: boundaries between different times and different spaces can dissolve, allowing mutually inconsistent chronologies and scales of size and distance to coexist. The world-view underlying this is governed by an inversion of the generally-agreed-upon relationship between observable phenomena and individual perception. Rather than using the outside world as a source of data from which to construct models of ‘objective’ reality, Milligan allows his characters’ own words to modify the given conditions of any situation. This quasi-magical principle of storytelling mirrors cognitive strategies used by children in their primary-school years to grasp and describe the complexities of time and space. Childlike and lighthearted as it often is, The Goon Show’s twisting of time and space has a parallel to some highly complex ‘grown-up’ thinking. Its implicit rejection of the self-evidence of the fundamental laws of Newtonian physics recalls more than just the challenge to these laws provided by relativity and quantum mechanics. It also anticipates, by a full generation, the skeptical stance towards the self-evidence of immutable laws which forms the cornerstone of postmodern critiques of all fields of endeavour. The Goon Show reveals Spike Milligan to be an unsung visionary: always striding into unknown conceptual territory, he let his scripts, rather than a body of theoretical work, articulate his vision. Milligan’s comedic touch and his inimitable strangeness have led him to be appreciated, rather than studied. The ways in which The Goon Show turns time and space inward on themselves demonstrate, however, that the First Mover Unmoved in the mad universe of Goonery was an artistic and intellectual force to be reckoned with. Further study of Spike Milligan can only to lead to a greater appreciation of how far ahead of his time he truly was.

Spike Milligan has had an undisputable influence on English-language comedy in the past half-century. Monty Python’s Terry Jones cites the “free-wheeling fantasy world” Milligan created for the surreal radio series The Goon Show as the chief inspiration for his own group’s more internationally-famous work. However, Milligan’s writing for The Goon Show, which first aired between 1951 and 1960 displays a depth beyond “the confidence to be silly” noted by Python’s Michael Palin. Milligan’s scripts reveal a deliberate, if not wholly conscious, rejection of the laws of causality and probability, through frequent and systematic distortions of time and space. The fictional world revealed in The Goon Show’s corpus of half-hour stories is one in which concepts relating to time and space lack the fixed meanings that we attach to them in everyday life. Temporal and spatial relationships are fluid and indeterminate: boundaries between different times and different spaces can dissolve, allowing mutually inconsistent chronologies and scales of size and distance to coexist. The world-view underlying this is governed by an inversion of the generally-agreed-upon relationship between observable phenomena and individual perception. Rather than using the outside world as a source of data from which to construct models of ‘objective’ reality, Milligan allows his characters’ own words to modify the given conditions of any situation. This quasi-magical principle of storytelling mirrors cognitive strategies used by children in their primary-school years to grasp and describe the complexities of time and space. Childlike and lighthearted as it often is, The Goon Show’s twisting of time and space has a parallel to some highly complex ‘grown-up’ thinking. Its implicit rejection of the self-evidence of the fundamental laws of Newtonian physics recalls more than just the challenge to these laws provided by relativity and quantum mechanics. It also anticipates, by a full generation, the skeptical stance towards the self-evidence of immutable laws which forms the cornerstone of postmodern critiques of all fields of endeavour. The Goon Show reveals Spike Milligan to be an unsung visionary: always striding into unknown conceptual territory, he let his scripts, rather than a body of theoretical work, articulate his vision. Milligan’s comedic touch and his inimitable strangeness have led him to be appreciated, rather than studied. The ways in which The Goon Show turns time and space inward on themselves demonstrate, however, that the First Mover Unmoved in the mad universe of Goonery was an artistic and intellectual force to be reckoned with. Further study of Spike Milligan can only to lead to a greater appreciation of how far ahead of his time he truly was.

Spike Milligan has had an undisputable influence on English-language comedy in the past half-century. Monty Python’s Terry Jones cites the “free-wheeling fantasy world” Milligan created for the surreal radio series The Goon Show as the chief inspiration for his own group’s more internationally-famous work. However, Milligan’s writing for The Goon Show, which first aired between 1951 and 1960 displays a depth beyond “the confidence to be silly” noted by Python’s Michael Palin. Milligan’s scripts reveal a deliberate, if not wholly conscious, rejection of the laws of causality and probability, through frequent and systematic distortions of time and space. The fictional world revealed in The Goon Show’s corpus of half-hour stories is one in which concepts relating to time and space lack the fixed meanings that we attach to them in everyday life. Temporal and spatial relationships are fluid and indeterminate: boundaries between different times and different spaces can dissolve, allowing mutually inconsistent chronologies and scales of size and distance to coexist. The world-view underlying this is governed by an inversion of the generally-agreed-upon relationship between observable phenomena and individual perception. Rather than using the outside world as a source of data from which to construct models of ‘objective’ reality, Milligan allows his characters’ own words to modify the given conditions of any situation. This quasi-magical principle of storytelling mirrors cognitive strategies used by children in their primary-school years to grasp and describe the complexities of time and space. Childlike and lighthearted as it often is, The Goon Show’s twisting of time and space has a parallel to some highly complex ‘grown-up’ thinking. Its implicit rejection of the self-evidence of the fundamental laws of Newtonian physics recalls more than just the challenge to these laws provided by relativity and quantum mechanics. It also anticipates, by a full generation, the skeptical stance towards the self-evidence of immutable laws which forms the cornerstone of postmodern critiques of all fields of endeavour. The Goon Show reveals Spike Milligan to be an unsung visionary: always striding into unknown conceptual territory, he let his scripts, rather than a body of theoretical work, articulate his vision. Milligan’s comedic touch and his inimitable strangeness have led him to be appreciated, rather than studied. The ways in which The Goon Show turns time and space inward on themselves demonstrate, however, that the First Mover Unmoved in the mad universe of Goonery was an artistic and intellectual force to be reckoned with. Further study of Spike Milligan can only to lead to a greater appreciation of how far ahead of his time he truly was.

archives@tulane.edu / Previous work has revealed a presynaptic cytosolic Na+-dependent regulation on vesicular glutamate content and mEPSC amplitude via activating vacuolar Na+/H+ exchangers (NHEs) expressed on the synaptic vesicles, suggesting a presynaptic determinant of quantal size for synaptic strength. However, it remains unknown how spike activities control intracellular Na+ at the axon terminals and how the fluctuation of presynaptic Na+ during activities modulates quantal content and contributes to synaptic strength. I studied these questions using the calyx of Held, a giant glutamatergic synapse. With two-photon Na+ imaging, I found that presynaptic Na+ substantially accumulated during spike firing in a frequency and duration-dependent manner. This spike-induced elevation of presynaptic Na+ gradually increased EPSC amplitude by solely affecting vesicular glutamate filling, which was further confirmed as increased amplitude of asynchronous released vesicles, but without affecting the size of readily releasable pool or neurotransmitter release probability. This Na+-dependent modulation of EPSC amplitude resulted in a change of the reliability of transferring presynaptic spike to postsynaptic firing. Finally, blockade of NHEs reduced both EPSC amplitude and reliability of synaptic signaling, suggesting that NHEs are required for presynaptic Na+ regulation of synaptic transmission. Recent studies demonstrated that a non-inactivation cation channel NALCN (Na+ leak channel, non-selective), characterized as a major Na+ leak channel, is widely expressed in the central nervous system. Immunostaining revealed the expression of NALCN channel at the calyceal terminals. In line with a role of NALCN in controlling the cell excitability, calyces with conditional knockout (cKO) of NALCN exhibited a more hyperpolarized resting membrane potential compared with the wildtype (WT) calyces. Blockade of NALCN with a non-specific blocker gadolinium (Gd3+) induced a reduction of basal Na+ level and mEPSC amplitude in the WT but not in cKO group, suggesting the involvement of presynaptic NALCN channels in regulating the vesicular glutamate content. More importantly, two-photon Ca2+ imaging showed that NALCN channels were permeable to Ca2+, and Gd3+ decreased the basal Ca2+ level in WT but not cKO calyces. The Ca2+ permeability was further confirmed by reduced sensitivity of mEPSC frequency in response to increased extracellular Ca2+ concentration in cKO and reduced initial release probability in response to application of Gd3+ to block NALCN channels in WT group. Finally, Gd3+ induced a stronger reduction of EPSC amplitude in WT group compared to cKO group. Overall, these data indicate that NALCN channels regulate glutamate transmission through modulation of both quantal size and initial release probability. / 1 / Dainan Li

No description available.

Abstract A modified thermal spike model initially proposed to account for defect formation in metals within the high heavy ion energy regime is adapted for describing the sputtering of Bi thin films under MeV Kr ions. Surface temperature profiles for both the electronic and atomic subsystems have been carefully evaluated versus the radial distance and time with introducing appropriate values of the Bi target electronic stopping power for multi-charged Kr15+ heavy ions as well as different target physical proprieties like specific heats and thermal conductivities. Then, the total sputtering yields of the irradiated Bi thin films have been determined from a spatiotemporal integration of the local atomic evaporation rate. Besides, an expected non negligible contribution of elastic nuclear collisions to the Bi target sputtering yields and ion-induced surface effects has also been considered in our calculation. Finally, the latter thermal spike model allowed us to derive numerical sputtering yields in satisfactorily agreement with existing experimental data both over the low and high heavy ion energy regions, respectively, dominated by elastic nuclear collisions and inelastic electronic collisions, in particular with our data taken recently for Bi thin films irradiated by 27.5 MeV Kr15+ heavy ions. An overall consistency of our model calculation with the predictions of sputtering yield theoretical models within the target nuclear stopping power regime was also pointed out.

No description available.

Advances in recording technologies now allow us to record populations of neurons simultaneously, data necessary to understand the network dynamics of the brain. Extracellular probes are fabricated with ever greater numbers of recording sites to capture the activity of increasing numbers of neurons. However, the utility of this extracellular data is limited by an initial analysis step, spike sorting, that extracts the activity patterns of individual neurons from the extracellular traces. Commonly used spike sorting methods require manual processing that limits their scalability, and errors can bias downstream analyses. Leveraging the replication of the activity from a single neuron on nearby recording sites, we designed a spike sorting method consisting of three primary steps: (1) a blind source separation algorithm to estimate the underlying source components, (2) a spike detection algorithm to find the set of spikes from each component best separated from background activity and (3) a classifier to evaluate if a set of spikes came from one individual neuron. To assess the accuracy of our method, we simulated multi-electrode array data that encompass many of the realistic variations and the sources of noise in in vivo neural data. Our method was able to extract individual simulated neurons in an automated fashion without any errors in spike assignment. Further, the number of neurons extracted increased as we increased recording site count and density. To evaluate our method in vivo, we performed both extracellular recording with our close-packed probes and a co-localized patch clamp recording, directly measuring one neuron’s ground truth set of spikes. Using this in vivo data we found that when our spike sorting method extracted the patched neuron, the spike assignment error rates were at the low end of reported error rates, and that our errors were frequently the result of failed spike detection during bursts where spike amplitude decreased into the noise. We used our in vivo data to characterize the extracellular recordings of burst activity and more generally what an extracellular electrode records. With this knowledge, we updated our spike detector to capture more burst spikes and improved our classifier based on our characterizations.