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See detailElectric and magnetic stimulation of human motor cortex: surface EMG and single motor unit responses.
Day, B. L.; Dressler, D.; MAERTENS DE NOORDHOUT, Alain ULg et al

in Journal of Physiology (1989), 412

1. The effects of different forms of brain stimulation on the discharge pattern of single motor units were examined using the post-stimulus time histogram (PSTH) technique and by recording the compound ... [more ▼]

1. The effects of different forms of brain stimulation on the discharge pattern of single motor units were examined using the post-stimulus time histogram (PSTH) technique and by recording the compound surface electromyographic (EMG) responses in the first dorsal interosseous (FDI) muscle. Electrical and magnetic methods were used to stimulate the brain through the intact scalp of seven normal subjects. Electrical stimuli were applied either with the anode over the lateral central scalp and the cathode at the vertex (anodal stimulation) or with the anode at the vertex and the cathode lateral (cathodal stimulation). Magnetic stimulation used a 9 cm diameter coil centred at the vertex; current in the coil flowed either clockwise or anticlockwise when viewed from above. 2. Supramotor threshold stimuli produced one or more narrow (less than 2 ms) peaks of increased firing in the PSTH of all thirty-two units studied. Anodal stimulation always produced an early peak. The latencies of the peaks produced by other forms of stimulation, or by high intensities of anodal stimulation, were grouped into four time bands relative to this early peak, at intervals of -0.5 to 0.5, 1-2, 2.5-3.5 and 4-5.5 ms later. Peaks occurring within these intervals are referred to as P0 (the earliest anodal), P1, P2 and P3 respectively. 3. At threshold, anodal stimulation evoked only the P0 peak; at higher intensities, the P2 or more commonly the P3 peak also was recruited. The size of the P0 peak appeared to saturate at high intensities. 4. In five of six subjects, cathodal stimulation behaved like anodal stimulation, except that there was a lower threshold for recruitment of the P2 or P3 peak relative to that of the P0 peak. In the other subject, the P3 peak was recruited before the P0 peak. 5. Anticlockwise magnetic [corrected] stimulation, at threshold, often produced several peaks. These always included a P1 peak, and usually a P3 peak. A P0 peak in the PSTH was never produced by an anticlockwise stimulation [corrected] at intensities which we could explore with the technique. 6. Clockwise magnetic [corrected] stimulation never recruited a P1 peak; in most subjects a P3 peak was recruited first and at higher intensities was accompanied by P0 or P2 peaks. 7. On most occasions when more than one peak was observed in a PSTH, the unit fired in only one of the preferred intervals after each shock. However, double firing was seen in five units when high intensities of stimulation were used.(ABSTRACT TRUNCATED AT 400 WORDS) [less ▲]

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See detailElectric control of the magnetization in BiFeO3/LaFeO3 superlattices
Zanolli, Zeila ULg; Wojdeł, Jacek; Iniguez, Jorge et al

in Physical Review B (2013), 88

First-principles techniques are used to investigate the behavior of BiFeO3/LaFeO3 perovskite oxide superlattices epitaxially grown on a (001)-SrTiO3 substrate. The calculations show that 1/1 superlattices ... [more ▼]

First-principles techniques are used to investigate the behavior of BiFeO3/LaFeO3 perovskite oxide superlattices epitaxially grown on a (001)-SrTiO3 substrate. The calculations show that 1/1 superlattices exhibit a Pmc21 ground state combining a trilinear coupling of one polar and two oxygen rotational lattice modes, and weak ferromagnetism. The microscopic mechanism allowing one to manipulate the magnetization with an electric field in such systems is presented and its dependence on strain and chemical substitution is discussed. BiFeO3/LaFeO3 artificial superlattices appear to be good candidates to achieve electric switching of magnetization at room temperature. [less ▲]

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See detailElectric Dipole Transitions in Atomic Oxygen and the lifetimes of the 2p3(4S°)3s5S° and 3S° States
Biémont, Emile ULg; Zeippen, C. J.

in Astronomy and Astrophysics (1992), 265

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See detailElectrical activity of the bovine uterus prior to and post parturition.
Hanzen, Christian ULg

in Veterinary Research Communications (1981), 5(2), 143-50

Recordings of electrical activity of six different areas of the uterus were obtained from two pregnant cows before and after delivery of their calves. Periods of activity occurred as spike bursts of ... [more ▼]

Recordings of electrical activity of six different areas of the uterus were obtained from two pregnant cows before and after delivery of their calves. Periods of activity occurred as spike bursts of potentials which occupied 52% of the recording time before delivery and 92% at the expulsive phase. The mean duration of the bursts was nearly doubled in the last ten hours prior to parturition without changes in their frequency. After delivery, the activity of the uterus occupied 29% of the recording time and consisted of long-lasting periods of spike bursts whose frequency was nearly halved. The alternation of periods of activity and quiescence represents the basic motility pattern of the pregnant uterus. Periods of quiescence are shortened at the time of expulsion and become predominant in the empty uterus, a phenomenon paralleled by changes in the temporal organisation of the number of spike bursts with the periods of activity. [less ▲]

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See detailElectrical Activity of Threading Dislocations and Defect Complexes in GeSn Epitaxial Layers
Gupta, Somya; Simoen, Eddy; Asano, Takanori et al

Conference (2013, June 04)

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See detailElectrical and dielectric properties of carbon black filled co-continuous two-phase polymer blends
Calberg, Cédric ULg; Blacher, Silvia ULg; Gubbels, F. et al

in Journal of Physics D - Applied Physics (1999), 32(13), 1517-1525

The electrical and dielectric properties of co-continuous polystyrene (PS)/ρoly(methylmethacrylate)(PMMA) blends loaded with carbon black (CB) of a special grade (BP 1000) have been studied. They strongly ... [more ▼]

The electrical and dielectric properties of co-continuous polystyrene (PS)/ρoly(methylmethacrylate)(PMMA) blends loaded with carbon black (CB) of a special grade (BP 1000) have been studied. They strongly depend on the selective localization of the CB particles at the blend interface quite consistently with the double percolation concept. The interfacial localization of CB contributes to the stabilization of the phase morphology against thermal post treatment. Nevertheless, the sample annealing has a very favourable effect on the percolation threshold that decreases The composition range in which phases are co-continuous is also increased by the addition of the filler. Dispersion of the conductance and the dielectric constant has been measured in the wide frequency range 10-4-108 Hz for blends containing 0-5 wt% CB. On the basis of these results, the mechanism of electrical transport (trapping, hopping, tunnelling, percolation) has been discussed in relation to the CB loading and the optimum loading has been identified for the electrical and dielectric properties to be stable and reproducible [less ▲]

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See detailElectrical and Magnetic Characterization of BSCCO and YBCO HTS Tapes for Fault Current Limiter Application
Lamas, Jerika S; Baldan, Carlos A; Shigue, Carlos Y et al

in IEEE Transactions on Applied Superconductivity (2011), 21(3), 3398-3402

Several high temperature superconductor (HTS) tapes have been developed since the late eighties. Due to the new techniques applied for their production, HTS tapes are becoming feasible and practical for ... [more ▼]

Several high temperature superconductor (HTS) tapes have been developed since the late eighties. Due to the new techniques applied for their production, HTS tapes are becoming feasible and practical for many applications. In this work, we present the test results of five commercial HTS tapes from the BSCCO and YBCO families (short samples of 200 mm). We have measured and analyzed their intrinsic and extrinsic properties and compared their behaviors for fault current limiter (FCL) applications. Electrical measurements were performed to determine the critical current and the n value through the V-I relationship under DC and AC magnetic fields. The resistance per unit length was determined as a function of temperature. The magnetic characteristics were analyzed through susceptibility curves as a function of temperature. As transport current generates a magnetic field surrounding the HTS material, the magnetic measurements indicate the magnetic field supported by the tapes under a peak current 1.5 times higher than the critical current, I(c). By pulsed current tests the recovery time and the energy/volume during a current fault were also analyzed. These results are in agreement with the data found in the literature giving the most appropriate performance conductor for a FCL device (I(peak) = 4 kA) to be used in a 220 V-60 Hz grid. [less ▲]

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See detailElectrical and mechanical activity of the cervix in the ewe during pregnancy and parturition.
Toutain, P. L.; Garcia-Villar, R.; Hanzen, Christian ULg et al

in Journal of Reproduction and Fertility (1983), 68

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See detailELECTRICAL AND THERMOMAGNETIC EFFECTS IN BI1.7PB0.3SR2CA2CU3O10 SUPERCONDUCTING CERAMICS
Pekala, M.; Bougrine, Hassan ULg; Ausloos, Marcel ULg

in Journal of Physics : Condensed Matter (1995), 7(28), 5607-5621

We report the electrical resistivity and thermoelectric power of polycrystalline Pb-doped Pi 2:2:2:3 superconductors. In particular the mixed-state properties are investigated by measuring the ... [more ▼]

We report the electrical resistivity and thermoelectric power of polycrystalline Pb-doped Pi 2:2:2:3 superconductors. In particular the mixed-state properties are investigated by measuring the longitudinal and transverse (Nernst) thermoelectric power. For the first time we show the presence of hysteresis in a high magnetic field for the Nernst effect. We discuss the variation with magnetic field in the properties with respect to the zero-field case and show the power-law behaviour with exponents depending on the transport quantity. We extract 'derived properties' such as the effective mass, the transport entropy, the Ginzburg-Landau parameter, the thermal Hall angle and the activation energy and compare them with previous data on related systems. [less ▲]

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See detailElectrical characterization of InGaN/GaN multiple-quantum-well structures by thermal admittance spectroscopy
Nguyen, Ngoc Duy ULg; Schmeits, Marcel; Germain, Marianne et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2002)

Experimental results of electrical characterization of InGaN/GaN multiple-quantum-well electrolu- minescence test structures obtained by thermal admittance spectroscopy are presented. The stu- died GaN ... [more ▼]

Experimental results of electrical characterization of InGaN/GaN multiple-quantum-well electrolu- minescence test structures obtained by thermal admittance spectroscopy are presented. The stu- died GaN : Mg/5 × (InGaN/GaN)/GaN:Si structures were grown on c-plane sapphire substrate by metal-organic vapor phase epitaxy. Admittance measurements were conducted from room tem- perature down to 125 K for a wide frequency range and for different applied bias voltages. Analy- sis of the capacitance versus frequency curves shows the presence of several cutoff frequencies which originate from the response of equivalent RC series circuits and give peaks in the conduc- tance divided by angular frequency. The dependence of the position and the amplitude of these peaks on temperature is discussed. [less ▲]

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See detailElectrical characterization of InGaN/GaN multiple-quantum-well structures by thermal admittance spectroscopy
Nguyen, Ngoc Duy ULg; Schmeits, Marcel; Germain, Marianne et al

Poster (2002)

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See detailElectrical characterization of pGeSn/nGe diodes
Baert, Bruno ULg; Gupta, Somya; Gencarelli, Federica et al

Conference (2014, June 03)

I-V characteristics of pGeSn/nGe diodes have been measured and show very good properties. Simulations of the same structure are able to reproduce most of the observed behavior and point to the ... [more ▼]

I-V characteristics of pGeSn/nGe diodes have been measured and show very good properties. Simulations of the same structure are able to reproduce most of the observed behavior and point to the predominating influence of parameters such as the band gap energy of the GeSn layer. C-V characteristics showing little frequency dependence have also been measured, and their analysis for the determination of the carrier concentration is confirmed by simulations. More investigations, including the effect of temperature and other defects at the interface or in the bulk of either layers are still required in order to explain some of the observed behaviors, notably the reverse saturation current. [less ▲]

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See detailElectrical characterization of semiconductor heterostructures by admittance spectroscopy
Nguyen, Ngoc Duy ULg

Scientific conference (2010, December 16)

Electrical characterization by admittance spectroscopy enables the study of interface properties of semiconductor structures such as p-n junctions, Schottky diodes, light-emitting systems, photodiodes ... [more ▼]

Electrical characterization by admittance spectroscopy enables the study of interface properties of semiconductor structures such as p-n junctions, Schottky diodes, light-emitting systems, photodiodes, solar cells or quantum well devices. The technique consists in monitoring the complex admittance of the device under test as a function of frequency, applied dc voltage and temperature. This method gives a direct access to the emission-capture processes occurring between an impurity level and the conduction or the valence band and leads to the determination of important electronic properties including the activation energy and the carrier capture cross sections. In the case of organic semiconductors, the field-dependent carrier mobility can be measured as well. However, the interpretation of the admittance curves is straightforward only under restrictive assumptions such as full ionization of the shallow dopant, with a concentration larger than the deep impurity concentration. Numerical simulations, based on the solution of the basic semiconductor equations, allow to carry out a detailed analysis of the steady-state and small-signal electrical characteristics of the systems and thus contribute to a better understanding of the conduction mechanisms and of the microscopic origin of the features in the experimental admittance spectra. In this presentation, the results obtained for different structures are shown in order to illustrate the method. [less ▲]

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