Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailMagnetocaloric effect of monovalent K doped manganites Pr0.6Sr0.4−xKxMnO3 (x=0 to 0.2)
Thaljaoui, R.; Boujelben, W.; Pękała, M. et al

in Journal of Magnetism and Magnetic Materials (2014), 352(0), 6-12

Magnetic and magnetocaloric properties are reported for polycrystalline monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3 (x=0, 0.05, 0.1, 0.15 and 0.2) crystallized in orthorhombic structure with ... [more ▼]

Magnetic and magnetocaloric properties are reported for polycrystalline monovalent potassium doped manganites Pr0.6Sr0.4−xKxMnO3 (x=0, 0.05, 0.1, 0.15 and 0.2) crystallized in orthorhombic structure with Pnma space group. The increasing K content shifts the paramagnetic to ferromagnetic transition temperature from 310 K for x=0 to 269 K for x=0.2. The magnetic entropy change under magnetic field variation of 2 T is found to be 1.95, 3.09, 2.89, 3.05 and 3.2 J/kgK for x varying from 0 to 0.2, respectively. The highest relative cooling power of 102 J/kg is observed for the undoped sample. The sensitivity of magnetic entropy change to magnetic field is estimated by a local N(T) exponent exhibiting the characteristic temperature variation. Phenomenological universal curves of entropy change and Arrott plots confirm the second order phase transition. [less ▲]

Detailed reference viewed: 14 (2 ULg)
Full Text
Peer Reviewed
See detailMagnetometry of a sample of massive stars in Carina
Nazé, Yaël ULg; Bagnulo, Stefano; Petit, Véronique et al

in Monthly Notices of the Royal Astronomical Society (2012), 423

X-ray surveys of the Carina nebula have revealed a few hard and luminous sources associated with early-type stars. Such unusual characteristics for the high-energy emission may be related to magnetically ... [more ▼]

X-ray surveys of the Carina nebula have revealed a few hard and luminous sources associated with early-type stars. Such unusual characteristics for the high-energy emission may be related to magnetically confined winds. To search for the presence of magnetic fields in these objects, we performed a limited spectropolarimetric survey using the Focal reducer and low dispersion spectrograph (FORS) instrument. The multi-object mode was used, so that a total of 21 OB stars could be investigated during a one-night-long run. A magnetic field was detected in two objects of the sample, with a 6σ significance: Tr16-22 and 13. Such a detection was expected for Tr16-22, as its X-ray emission is too bright, variable and hard, compared to other late-type O or O+OB systems. It is more surprising for Tr16-13, a poorly known star which so far has never shown any peculiar characteristics. Subsequent monitoring is now needed to ascertain the physical properties of these objects and enable a full modelling of their magnetic atmospheres and winds. Based on data collected at ESO under Program ID 386.D-0624A. [less ▲]

Detailed reference viewed: 24 (1 ULg)
Full Text
See detailMagnetopause Boundary Normal Analysis at Jupiter and Saturn: Evidence of Kelvin Hemholtz Vorticies
Stauffer, Blake Hughes; Delamere, Peter A; Ma, Xuanye et al

Poster (2013, December 10)

Identification of surface waves and Kelvin Hemholtz (KH) vorticies at the magnetopause boundary at Jupiter and Saturn is critical to understanding interaction between the solar wind and their planetary ... [more ▼]

Identification of surface waves and Kelvin Hemholtz (KH) vorticies at the magnetopause boundary at Jupiter and Saturn is critical to understanding interaction between the solar wind and their planetary magnetospheres. The rapid rotation of those planets coincides with a co-rotating plasma that creates an asymmetry between the formation and evolution of surface waves on either side of the sub-solar point. Minimum variance analysis and other techniques are performed on hundreds of select crossings of Saturn's magnetopause from 2004 to 2012 by the Cassini spacecraft and 47 crossings at Jupiter's magnetopause by the Galileo spacecraft. It is compared to the boundary normals of a simple magnetopause model. The wide range in angular difference between the model and the analysis is evidence of the presence of KH instability vorticies at the magnetopause boundary. Furthermore, boundary crossings from the magnetosheath into the magnetosphere on the dusk flanks are dominated by shallower angles, consistent with MHD simulations of variable shear flows on the dayside magnetopause boundary. [less ▲]

Detailed reference viewed: 24 (2 ULg)
Full Text
Peer Reviewed
See detailMagnetosonic modes with a beam of dust or secondary ions
Cramer, N. F.; Verheest, F.; Cattaert, Tom ULg et al

in Physics of Plasmas (2004), 11(10), 4589-4595

Charged dust particles on near-Keplerian orbits in planetary rings drift relative to the corotating background plasma, and this relative streaming may drive dust-modified magnetosonic waves unstable ... [more ▼]

Charged dust particles on near-Keplerian orbits in planetary rings drift relative to the corotating background plasma, and this relative streaming may drive dust-modified magnetosonic waves unstable. Using a magnetofluid model, this situation is revisited, and it is shown that a correct description can be obtained at frequencies and Doppler shifts that are small compared to the electron gyrofrequency. An excellent agreement is reached between the analytical approximation and the numerical solution of the full or reduced dispersion law. A very low-frequency, small wave number beam instability may occur at supermagnetosonic beam velocities of the dust component, but, based on the existing data, is unlikely to play a role in planetary rings. Instability is also found for submagnetosonic speeds, which might be relevant to Saturn's E ring. (C) 2004 American Institute of Physics. [less ▲]

Detailed reference viewed: 24 (3 ULg)
Full Text
See detailMagnetospheric dynamics at Jupiter and Saturn
Palmaerts, Benjamin ULg

Speech/Talk (2014)

Detailed reference viewed: 17 (5 ULg)
Full Text
Peer Reviewed
See detailMagnetospheric Science Objectives of the Juno Mission
Bagenal, Fran; Adriani, A.; Allegrini, F. et al

in Space Science Reviews (2014)

In July 2016, NASA’s Juno mission becomes the first spacecraft to enter polar orbit of Jupiter and enture deep into unexplored polar territories of the magnetosphere. Focusing on these polar regions, we ... [more ▼]

In July 2016, NASA’s Juno mission becomes the first spacecraft to enter polar orbit of Jupiter and enture deep into unexplored polar territories of the magnetosphere. Focusing on these polar regions, we review current understanding of the structure and dynamics of the magnetosphere and summarize the outstanding issues. The Juno mission profile involves (a) a several-week approach from the dawn side of Jupiter’s magnetosphere, with an orbit-insertion maneuver on July 6, 2016; (b) a 107-day capture orbit, also on the dawn flank; and (c) a series of thirty 11-day science orbits with the spacecraft flying over Jupiter’s poles and ducking under the radiation belts. We show how Juno’s view of the magnetosphere evolves over the year of science orbits. The Juno spacecraft carries a range of instruments that take particles and fields measurements, remote sensing observations of auroral emissions at UV, visible, IR and radio wavelengths, and detect microwave emission from Jupiter’s radiation belts. We summarize how these Juno measurements address issues of auroral processes, microphysical plasma physics, ionosphere-magnetosphere and satellite-magnetosphere coupling, sources and sinks of plasma, the radiation belts, and the dynamics of the outer magnetosphere. To reach Jupiter, the Juno spacecraft passed close to the Earth on October 9, 2013, gaining the necessary energy to get to Jupiter. The Earth flyby provided an opportunity to test Juno’s instrumentation as well as take scientific data in the terrestrial magnetosphere, in conjunction with ground-based and Earth-orbiting assets. [less ▲]

Detailed reference viewed: 35 (5 ULg)
Full Text
Peer Reviewed
See detailMagnetostructural effects in ligand stabilized Pd13 clusters: a density functional theory study
Fresch, Barbara ULg; Boyen, H.-G.; Remacle, Françoise ULg

in Nanoscale (2012), 4(14), 4138-4147

Detailed reference viewed: 25 (10 ULg)
Peer Reviewed
See detailMagnetotail topology around substorm onset time
Meurant, M.; Donovan, E. F.; Gérard, Jean-Claude ULg et al

Conference (2006, December 01)

The time evolution of the magnetotail topology during minutes preceding and following substorm onset is an important question of the magnetospheric dynamic. The substorm onset is a local and explosive ... [more ▼]

The time evolution of the magnetotail topology during minutes preceding and following substorm onset is an important question of the magnetospheric dynamic. The substorm onset is a local and explosive phenomenon, which makes it difficult to describe with in situ data. In this study, we investigate this problem thanks the remote sensing data provided by the FUV camera onboard the IMAGE spacecraft. In the first part of this study, we use a set of IMAGE-FUV and GOES-8 simultaneous observations obtained during substorms periods to develop a model of the magnetic field elevation angle at geosynchronous orbit. In the second part, we use a set of 259 substorms observed by the IMAGE spacecraft between 2000 and 2002. Taking advantage of the global scale of the observations provided by IMAGE-FUV, we describe the time evolution of the magnetotail topology provided by the model. An interesting result shows that the field is symmetrically stretched around the onset position before the onset time and this symmetry is broken after onset, with a more important stretching duskward to the onset. [less ▲]

Detailed reference viewed: 20 (9 ULg)
Full Text
Peer Reviewed
See detailMagnetotransport of La0.5Ba0.5MnO3
Pekala, Marek; Drozd, V.; Fagnard, Jean-François ULg et al

in Journal of Applied Physics (2009), 105(1), 013923-013923-8

Physical properties of polycrystalline La0.5Ba0.5MnO3 are reported from low temperature (10 K) up to above room temperature. An aim has been to obtain microscopic parameters and to search for the ... [more ▼]

Physical properties of polycrystalline La0.5Ba0.5MnO3 are reported from low temperature (10 K) up to above room temperature. An aim has been to obtain microscopic parameters and to search for the characteristic lengths in terms of which one can discuss the interplay between magnetic, electric, and phonon excitations. The structural and magnetotransport measurements reveal a set of relatively high transition temperatures (near 300 K) between ferromagnetic/metallic and paramagnetic/semiconducting phases. It is found, in particular, that the so-called localization length increases from 0.085 to 0.24 nm when the magnetic field varies from 0 to 8 T. Moreover a “special field value” ~0.03 T is observed in the description of the electrical resistance. It cannot be presently distinguished whether it is the signature of a spin reorientation transition in the canted phase or a mere saturation field for aligning magnetic domains. The relatively high magnetoresistance effect (~=55% at 8 T and 10 K) makes the La0.5Ba0.5MnO3 a very interesting material for among others sensor applications. [less ▲]

Detailed reference viewed: 72 (11 ULg)
Full Text
Peer Reviewed
See detailMagnetotransport properties of a single grain boundary in a bulk La-Ca-Mn-O material
Vertruyen, Bénédicte ULg; Cloots, Rudi ULg; Rulmont, André ULg et al

in Journal of Applied Physics (2001), 90(11), 5692-5697

Besides the "intrinsic" colossal magnetoresistance effect observed in single crystals, the polycrystalline manganate compounds also exhibit an "extrinsic" magnetoresistance related to the presence of ... [more ▼]

Besides the "intrinsic" colossal magnetoresistance effect observed in single crystals, the polycrystalline manganate compounds also exhibit an "extrinsic" magnetoresistance related to the presence of grain boundaries. We report electrical transport and magnetic measurements carried out on a bigrain sample extracted from a floating zone method-grown rod of calcium doped lanthanum manganate. Electrical resistance was measured both within a grain and across the grain boundary, between 20 and 300 K and from 0 to 8 T. Magnetoresistance values up to 99% are reached within the grain. The temperature dependence of the resistance across the grain boundary displays a "foot-like" feature towards the bottom of the transition. Low field and high field magnetoresistance effects are examined. We compare our results for a "bulk" grain boundary to those obtained by other authors for bicrystal thin films and bulk polycrystalline materials. (C) 2001 American Institute of Physics. [less ▲]

Detailed reference viewed: 33 (14 ULg)
Full Text
Peer Reviewed
See detailMagnetotransport study of MgB2 superconductor
Mucha, Jan ULg; Pekala, Marek; Szydlowska, Jadwiga et al

in Superconductor Science and Technology (2003), 16(10), 1167-1172

Precise magnetotransport studies of heat and charge carriers in polycrystalline MgB2 show that magnetic fields up to 8 T remarkably influence electrical resistivity, thermoelectric power and thermal ... [more ▼]

Precise magnetotransport studies of heat and charge carriers in polycrystalline MgB2 show that magnetic fields up to 8 T remarkably influence electrical resistivity, thermoelectric power and thermal conductivity. The superconducting transition temperature shifts from 39 K to 19 K at 8 T as observed on electric signals. The temperature transition width is weakly broadened. Electron and phonon contributions to the thermal conductivity are separated and discussed. The Debye temperature calculated from a phonon drag thermoelectric power component is inconsistent with values derived through other effects. [less ▲]

Detailed reference viewed: 130 (4 ULg)
Full Text
Peer Reviewed
See detailMagnette Charles
Lanneau, Catherine ULg

in Nouvelle biographie nationale (2014)

Detailed reference viewed: 10 (2 ULg)
Full Text
Peer Reviewed
See detailThe magnitude and the extinction duration of the cocaine-induced conditioned locomotion-activated response are related to the number of cocaine injections paired with the testing context in C57BL/6J mice
Michel, Anne; Tambour, Sophie ULg; Tirelli, Ezio ULg

in Behavioural Brain Research (2003), 145(1-2), 113-123

Behavioural activation repeatedly induced by a stimulant in rodents can persist in the absence of the drug if the animals are tested in the context where the drug was previously given, a phenomenon often ... [more ▼]

Behavioural activation repeatedly induced by a stimulant in rodents can persist in the absence of the drug if the animals are tested in the context where the drug was previously given, a phenomenon often explained in terms of Pavlovian conditioning. The aim of this study was to verify whether the amplitude of the putative CR (the drug-like activity) increases with the number of the US-CS associations (the number of drug-context pairings), one of the most representative rules of Pavlovian conditioning. The effect of the number of trials on the speed of extinction was also considered. C57BL/6J mice received 3, 6 or 12 once-daily injections of either saline or 12 mg/kg (-)-cocaine hydrochloride (s.c.) in the same test context, a photocell activity-box in which they were tested for 60 min after every injection. Other groups received the same treatments outside of the test context (being placed in a novel cage tub after each injection). Twenty-four hours after the last treatment session, all mice were challenged with saline in the test context (test for conditioned activity), extinction sessions taking place on the three subsequent days. Sensitisation to the locomotor-activating effect of cocaine developed only amongst the animals injected 6 or 12 times, the magnitude of the last sensitised response being comparable for these two injections regimen. On saline challenge, only the animals that had received 6 or 12 cocaine injections showed significant conditioned activity (CR), with the greatest response occurring following 12 injections. The 6-trial group reached the level of non-significance after fewer extinction sessions than the 12-trial group; however, the rates of extinction did not differ (comparable regression coefficients and quasi-parallel curves). These results suggest that the amplitude of the CR (cocaine-like stimulation after saline), and perhaps less convincingly the duration of extinction, are functions of the number of the US-CS (cocaine-context) pairings, supporting the Pavlovian nature of post-sensitisation placebo drug-like effects. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 13 (1 ULg)
Full Text
Peer Reviewed
See detailMagnitude comparison in preschoolers: what counts ? Influence of perceptual variables.
Rousselle, Laurence ULg; Palmers, Emmanuelle; Noël, Marie-Pascale

in Journal of Experimental Child Psychology (2004), 87

Detailed reference viewed: 11 (0 ULg)
See detailMagnitude representation in children: Its development and dysfunction
Noël, Marie-Pascale; Rousselle, Laurence ULg

in Campbell, Jamie (Ed.) Handbook of Mathematical Cognition (2005)

Detailed reference viewed: 11 (0 ULg)
Full Text
Peer Reviewed
See detailMagnitude Representations in Williams Syndrome: Differential Acuity in Time, Space and Number Processing.
Rousselle, Laurence ULg; Dembour, Guy; Noël, Marie-Pascale

in PLoS ONE (2013), 8(8), 72621

Detailed reference viewed: 11 (0 ULg)
See detailMagnitudes des étoiles doubles.
Renson, Pierre ULg

in Ciel et Terre (1993), 109

Not Available

Detailed reference viewed: 9 (0 ULg)