Single thermal plume in locally heated vertical soap films

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 84

Single-cell activity and local field potentials in the ventral tegmental area of awake, freely moving rats

Poster (2012, October 16)

The ventral tegmental area (VTA) is known to be involved in reward analysis and detection of salience of events. It contains dopaminergic (DA), GABAergic and perhaps other neurons. Much is known about the ... [more ▼]

The ventral tegmental area (VTA) is known to be involved in reward analysis and detection of salience of events. It contains dopaminergic (DA), GABAergic and perhaps other neurons. Much is known about the activity of DA neurons in anaesthetized animals and brain slices. However, there is a clear lack of data on their dynamic regulation in awake animals, although their reactivity to drugs of abuse, for example, is dramatically different in these different conditions (Koulchitsky et al., 2012). Moreover, little is known about the network activity of the VTA. <br /><br />Using a telemetric recording system and 8-microelectrode-arrays, spanning most of the extent of the VTA, we observed both single cell activity and local field potentials (LFPs), as recently described by others (Fujisawa and Buzsáki, 2011). Neurons were considered as being DA when their firing rate was decreased by more than 50% by an i.p. injection of 100 µg/kg of quinpirole. <br /><br />The firing rate of individual DA neurons was very variable over time, as was the spectrum of LFPs. In many cases, sharp changes in the firing rate/bursting of some DA neurons correlated with an increase in the amplitude of the theta band (~5-8 Hz). They were also coherent to the locomotor activity of the animals. However, the extent to which the firing rate of individual neurons within a rat correlated with the increased theta rhythm was very variable, suggesting that the functional connectivity of different DA neurons at a given moment is quite heterogenous. We are currently attempting to use our recordings to infer a “functional topography” of the VTA. [less ▲]

Single-mode microwave-assisted atom transfer radical polymerization catalyzed by [RuCl2(p-cymene)(PCy3)]

in Macromolecular Rapid Communications (2007), 28(4), 492-503

In the atom transfer radical polymerization (ATRP) of methyl methacrylate in the presence of [RuCl2(p-cymene)(PCy3)] (p-cymene=4-isopropyltoluene, PCy3=tricyclohexylphosphine), a microwave effect is noted ... [more ▼]

In the atom transfer radical polymerization (ATRP) of methyl methacrylate in the presence of [RuCl2(p-cymene)(PCy3)] (p-cymene=4-isopropyltoluene, PCy3=tricyclohexylphosphine), a microwave effect is noted which strikingly depends on both the temperature and the method used (conventional microwave synthesis (CMS, i.e., without simultaneous cooling) or enhanced microwave synthesis (EMS, with simultaneous cooling)). Thus, between 85 and 120 degrees C under CMS conditions, microwave-assisted polymerizations take place in a controlled fashion, and at 120 degrees C the microwave-assisted polymerization is three times faster than the conventionally heated protocol. However, from 130 degrees C, microwave irradiation has a deleterious effect and the polymerizations are no longer controlled. Likewise, using the EMS method in the temperature range of 85-120 degrees C results in uncontrolled processes, as indicated by the unsuccessful resumption of the polymerizations. These failures might be attributed to a significantly high concentration of radical species, which results in enhanced propagation and termination - mostly disproportionation - rates. [less ▲]

Single-nucleons potentials in the framework of a relativistic approach of nuclear matter,

in Physics Letters B (1982), 116

Single-player games: introduction to a new solving method

Master of advanced studies dissertation (2006)

In many games, the machine has become stronger than the best human players. Machines have already beaten the human World Champion in famous games like Checkers, Chess, Scrabble and Othello. However ... [more ▼]

In many games, the machine has become stronger than the best human players. Machines have already beaten the human World Champion in famous games like Checkers, Chess, Scrabble and Othello. However, mankind has not been humbled by chips in all games. The best human players are still stronger than computers in games like Go, Poker, Chinese Chess and Hex. In this thesis, we will focus on a new way to model single-player games in order to improve the performances of the machine. We will demonstrate this technique on the game of Sokoban. [less ▲]

Single-step reactive extrusion of PLLA in a corotating twin-screw extruder promoted by 2-ethylhexanoic acid tin(II) salt and triphenylphosphine

in Polymer (2000), 41(9), 3395-3403

The ring opening polymerisation of L,L-lactide using an equimolar complex of 2-ethylhexanoic acid tin(II) salt Sn(Oct)2 and triphenylphosphine P( )3 as catalyst shows for the first time a reactivity ... [more ▼]

The ring opening polymerisation of L,L-lactide using an equimolar complex of 2-ethylhexanoic acid tin(II) salt Sn(Oct)2 and triphenylphosphine P( )3 as catalyst shows for the first time a reactivity providing a polymerisation propagation rate fast enough to imagine a continuous single-step reactive extrusion process for bulk polymerisation. The ring opening polymerisation has been realised on a corotating closely intermeshing twin-screw extruder, using a specially designed screw concept to provide sufficient energy input and mixing for further enhancement of the propagation rate, without detrimentally enhancing depolymerisation or transesterification reactions. Using one chosen screw and processing concept on a twin-screw extruder with 25 mm diameter and a L/D-ratio of 48, the influence of different processing parameters on the resulting molecular parameters of the Polylactide (PLA) has been determined. Furthermore, the mechanical property profile of the generated PLA-polymers is discussed and related to the molecular parameters. [less ▲]

Single-trial EEG source reconstruction for brain-computer interface.

in IEEE Transactions on Biomedical Engineering (2008), 55(5), 1592-601

A new way to improve the classification rate of an EEG-based brain-computer interface (BCI) could be to reconstruct the brain sources of EEG and to apply BCI methods to these derived sources instead of ... [more ▼]

A new way to improve the classification rate of an EEG-based brain-computer interface (BCI) could be to reconstruct the brain sources of EEG and to apply BCI methods to these derived sources instead of raw measured electrode potentials. EEG source reconstruction methods are based on electrophysiological information that could improve the discrimination between BCI tasks. In this paper, we present an EEG source reconstruction method for BCI. The results are compared with results from raw electrode potentials to enable direct evaluation of the method. Features are based on frequency power change and Bereitschaft potential. The features are ranked with mutual information before being fed to a proximal support vector machine. The dataset IV of the BCI competition II and data from four subjects serve as test data. Results show that the EEG inverse solution improves the classification rate and can lead to results comparable to the best currently known methods. [less ▲]

Singlet oxygen production by merocyanine 540

Conference (1987)

Singlet Oxygen Quantum Yield of Sulfur and Selenium Analogs of Psoralen

in Photochemistry and Photobiology (1992), 56(3), 409-412

The quantum yield of singlet oxygen production by eight newly synthesized sulfur and selenium analogs of psoralen irradiated with UV-A (366 nm) has been determined in CCl4 with the help of the steady ... [more ▼]

The quantum yield of singlet oxygen production by eight newly synthesized sulfur and selenium analogs of psoralen irradiated with UV-A (366 nm) has been determined in CCl4 with the help of the steady state luminescence technique. The new psoralen derivatives are generally better singlet oxygen producers than psoralen itself. In particular, the replacement of selenophene for furan and/or of thiopyrone for pyrone induces an important enhancement of the singlet oxygen quantum yield. [less ▲]

Singlet-triplet excitation ratios in Ne III, Ar III and N II under ion impact

in European Physical Journal D -- Atoms, Molecules, Clusters & Optical Physics (2001), 15

Peculiar properties of ion-atom collision systems, in particular deviations from statistical populations of singlet and triplet levels, can be studied by optical spectroscopy.We have extended earlier ... [more ▼]

Peculiar properties of ion-atom collision systems, in particular deviations from statistical populations of singlet and triplet levels, can be studied by optical spectroscopy.We have extended earlier studies by VUV spectroscopy of a number of collision systems at various collision energies in the 0.01-MeV/nucleon to 1-MeV/nucleon range, involving H+ 2 , H+, He+, He2+, Ne+, Ar+, and N+ 2 as projectiles and Ne, Ar, and N2 as target gases. Statistically signi cant deviations of the relative intensities of singlet and triplet lines from simple ratios are observed in the displaced terms of the valence shell of Ne III, corroborating and extending earlier work. For Ar III, the energy dependences of singlet-to-triplet excitation ratios are very different for dff erent projectiles. For NII, in contrast, all observed line ratios are practically independent of the projectile energy. [less ▲]