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 detailCognitive reserve impacts on inter-individual variability in resting-state cerebral metabolism in normal aging
Bastin, Christine ULg; Yakushev, Igor; Bahri, Mohamed Ali ULg et al

in NeuroImage (2012), 63

There is a great deal of heterogeneity in the impact of aging on cognition and cerebral functioning. One potential factor contributing to individual differences among the elders is the cognitive reserve ... [more ▼]

There is a great deal of heterogeneity in the impact of aging on cognition and cerebral functioning. One potential factor contributing to individual differences among the elders is the cognitive reserve, which designates the partial protection from the deleterious effects of aging that lifetime experience provides. Neuroimaging studies examining task-related activation in elderly people suggested that cognitive reserve takes the form of more efficient use of brain networks and/or greater ability to recruit alternative networks to compensate for age-related cerebral changes. In this multi-centre study, we examined the relationships between cognitive reserve, as measured by education and verbal intelligence, and cerebral metabolism at rest (FDG-PET) in a sample of 74 healthy older participants. Higher degree of education and verbal intelligence was associated with less metabolic activity in the right posterior temporoparietal cortex and the left anterior intraparietal sulcus. Functional connectivity analyses of resting-state fMRI images in a subset of 41 participants indicated that these regions belong to the default mode network and the dorsal attention network respectively. Lower metabolism in the temporoparietal cortex was also associated with better memory abilities. The findings provide evidence for an inverse relationship between cognitive reserve and resting-state activity in key regions of two functional networks respectively involved in internal mentation and goal-directed attention. [less ▲]

Detailed reference viewed: 90 (6 ULg)
Peer Reviewed
See detailCognitive reserve, recollection and familiarity in normal aging, Mild Cognitive Impairment and Alzheimer's disease
Laisney, Mickaël; Salmon, Eric ULg; Bastin, Christine ULg

in Proceedings of the Annual Meeting of the Belgian Association for Psychological Sciences (2013)

Detailed reference viewed: 9 (0 ULg)
Full Text
Peer Reviewed
See detailCognitive support for a better handoff: does it improve the quality of medical communication at shift change in an emergency department?
Gillet, Aline ULg; GHUYSEN, Alexandre ULg; BONHOMME, Suzanne ULg et al

in European Journal of Emergency Medicine (2015), 22(3), 192-198

AIM: To improve the communication during shift handover in an emergency department. METHODS: We observed the handover process and analysed the discourse between physicians at shift change first, and then ... [more ▼]

AIM: To improve the communication during shift handover in an emergency department. METHODS: We observed the handover process and analysed the discourse between physicians at shift change first, and then we created two cognitive tools and tested their clinical impact on the field. We used different measures to evaluate this impact on the health care process including the frequency and type of information content communicated between physicians, duration of the handoff, physician self-evaluation of the quality of the handoff and a posthandover study of patient handling. RESULTS: Our results showed that the patient's medical history, significant test results, recommendations (treatment plan) and patient follow-up were communicated to a greater extent when the tools are used. We also found that physicians spent more time at the bedside and less time consulting medical records using these tools. CONCLUSION: The present study showed how in-depth observations and analyses of real work processes can be used to better support the quality of patient care. [less ▲]

Detailed reference viewed: 110 (36 ULg)
Full Text
Peer Reviewed
See detailCognitive topography imbalance in alcoholism
Papart, Patrick ULg; Liota, F.; Bartholomé, F. et al

in Journal of Psychophysiology (2003), 17(Suppl 1), 7-8

Detailed reference viewed: 17 (1 ULg)
See detailLes cognitivismes: Progrès, régression ou suicide de la psychologie ?
Richelle, Marc ULg

in Siguan, Miguel (Ed.) Comportement, cognition, conscience: La psychologie à la recherche de son objet (1987)

Detailed reference viewed: 71 (0 ULg)
See detailLa cohabitation de l'urbanisme commercial et de l'urbanisme général
Pâques, Michel ULg

in Le commerce et la ville en Europe (2002)

Detailed reference viewed: 34 (1 ULg)
Full Text
See detailLa cohabitation entre les deux types d'agriculture doit prévaloir
Vancutsem, Françoise ULg

in Matriche, Joel (Ed.) Le Soir (2010)

Detailed reference viewed: 31 (3 ULg)
Full Text
See detailLa cohabitation entre les deux types d'agriculture doit prévaloir
Vancutsem, Françoise ULg

Article for general public (2010)

Detailed reference viewed: 17 (3 ULg)
Full Text
See detailCoherence and many-body effects in the transport of Bose–Einstein condensates
Dujardin, Julien ULg

Doctoral thesis (2015)

This thesis presents investigations on the interplay of coherence and many-body effects in the quasi one-dimensional transport of Bose-Einstein condensates (BEC) through scattering potentials. Such ... [more ▼]

This thesis presents investigations on the interplay of coherence and many-body effects in the quasi one-dimensional transport of Bose-Einstein condensates (BEC) through scattering potentials. Such configurations can be realized with guided atom lasers that provide a coherent atomic beam. An exact theoretical description of the dynamics is out of reach due to the presence atom-atom interactions. Different levels of approximations are nevertheless possible with their strengths and weaknesses. The mean-field approximation, where the dynamics of the BEC is governed by the Gross-Pitaevskii equation, is most commonly used in the field of ultracold atoms. In this thesis the truncated Wigner method is used to go beyond the standard Gross-Pitaevskii description. This method is adapted in order to study the scattering of Bose-Einstein condensates in one-dimensional waveguides where atom-atom interactions and external potentials are nonvanishing only in a finite region of space. In this case, the truncated Wigner method is combined with the smooth exterior complex scaling method and incorporates quantum noise that originate from the vacuum fluctuations in the waveguide. Inelastic scattering is shown to play a major role in the resonant transport of BEC through a symmetric double potential barrier effectively forming an atomic quantum dot. Indeed, fully resonant transmission is prohibited and incoherent atoms as well as collective oscillations are detected in the transmitted beam. It is also shown that inelastic scattering destroys Anderson localization in the case of transport through disordered potentials. The classical (incoherent) ohmic transmission is recovered for finite atom-atom interactions. The validity of the truncated Wigner method is then assessed using the semiclassical van Vleck-Gutzwiller propagator in the Fock space of the many-body system. It is shown that the truncated Wigner method corresponds to the so-called diagonal approximation, and it is possible to identify the leading correction to the truncated Wigner results, which is provided by the so-called coherent backscattering (CBS) contribution. Coherent basckattering in Fock space is a genuine quantum many-body effect that lies beyond the reach of any mean-field approach. For the case of closed Bose-Hubbard models, the relevance of CBS is confirmed by numerically comparing the (classical) truncated Wigner evolution probabilities to the exact quantum probabilities in Bose-Hubbard models: While a CBS-induced enhancement of the return probability to the initial state is clearly seen in the exact quantum simulations of the bosonic many-body system, this enhancement is absent in the classical calculations. The magnitude and dependence of the CBS contribution on gauge fields, which break time-reversal invariance, is numerically confirmed. For the case of disordered open systems, it can be shown that this contribution as well as next-to leading order contributions vanish thereby confirming the validity of the truncated Wigner method. [less ▲]

Detailed reference viewed: 111 (20 ULg)
Full Text
Peer Reviewed
See detailCohérences
Pagnoulle, Christine ULg

Conference (2009)

Starting from seven illustrations my contribution shows the diversity of approaches that are required to capture or restore the consistency of a text.

Detailed reference viewed: 30 (9 ULg)
Full Text
Peer Reviewed
See detailCoherent and incoherent second harmonic generation in planar G-shaped nanostructures
Mamonov, E. A.; Murzina, T. V.; Kolmychek, I. A. et al

in Optics Letters (2011), 36(18), 3681-3683

Azimuthal anisotropy of Stokes parameters of the second harmonic generation ( SHG) generated and observed in reflection from a periodic planar area of G-shaped gold nanostructures is studied. A strong ... [more ▼]

Azimuthal anisotropy of Stokes parameters of the second harmonic generation ( SHG) generated and observed in reflection from a periodic planar area of G-shaped gold nanostructures is studied. A strong anisotropy of both coherent and incoherent SHG components is observed. Finite-difference time-domain calculations prove that the observed effects are due to the anisotropic enhancement of the fundamental radiation within the G-shaped structures. (C) 2011 Optical Society of America [less ▲]

Detailed reference viewed: 30 (2 ULg)
Peer Reviewed
See detailCoherent and random sequences in financial fluctuations
Vandewalle, Nicolas ULg; Ausloos, Marcel ULg

in Physica A: Statistical Mechanics and its Applications (1997), 246(3-4), 454-459

The detrended fluctuation analysis (DFA) is used to sort out temporal correlations in financial data. Its usefulness for the investigations of long-range power-law correlations in economic sequences is ... [more ▼]

The detrended fluctuation analysis (DFA) is used to sort out temporal correlations in financial data. Its usefulness for the investigations of long-range power-law correlations in economic sequences is shown. Our findings of persistent and antipersistent sequences are surprisingly similar to those for DNA sequences which appeared as a mosaic of coding and non-coding patches. [less ▲]

Detailed reference viewed: 29 (2 ULg)
Full Text
Peer Reviewed
See detailCoherent Backscattering in Fock Space: A Signature of Quantum Many-Body Interference in Interacting Bosonic Systems
Engl, Thomas; Dujardin, Julien ULg; Argüelles, Arturo et al

in Physical Review Letters (2014), 112

We predict a generic signature of quantum interference in many-body bosonic systems resulting in a coherent enhancement of the average return probability in Fock space. This enhancement is robust with ... [more ▼]

We predict a generic signature of quantum interference in many-body bosonic systems resulting in a coherent enhancement of the average return probability in Fock space. This enhancement is robust with respect to variations of external parameters even though it represents a dynamical manifestation of the delicate superposition principle in Fock space. It is a genuine quantum many-body effect that lies beyond the reach of any mean-field approach. Using a semiclassical approach based on interfering paths in Fock space, we calculate the magnitude of the backscattering peak and its dependence on gauge fields that break time-reversal invariance. We confirm our predictions by comparing them to exact quantum evolution probabilities in Bose-Hubbard models, and discuss their relevance in the context of many-body thermalization. [less ▲]

Detailed reference viewed: 62 (5 ULg)
Full Text
See detailCoherent backscattering in the Fock space of a disordered Bose-Hubbard system
Engl, Thomas; Dujardin, Julien; Tisserond, Emilie et al

Poster (2015, June)

We predict a generic signature of quantum interference in many-body bosonic systems resulting in a coherent enhancement of the average return probability in Fock space [1]. This enhancement is robust with ... [more ▼]

We predict a generic signature of quantum interference in many-body bosonic systems resulting in a coherent enhancement of the average return probability in Fock space [1]. This enhancement is robust with respect to variations of external parameters even though it represents a dynamical manifestation of the delicate superposition principle in Fock space. It is a genuine quantum many-body effect which lies beyond the reach of any mean-field approach. Using a semiclassical approach based on interfering paths in Fock space, we calculate the magnitude of the backscattering peak and its dependence on gauge fields that break time-reversal invariance. We confirm our predictions by comparing them to exact quantum evolution probabilities in Bose-Hubbard models, and discuss their relevance in the context of many-body thermalization. We furthermore propose a specific experimental setup in order to detect this many-body coherent backscattering phenomenon with ultracold bosonic atoms. [1] T. Engl, J. Dujardin, A. Argüelles, P. Schlagheck, K. Richter, and J. D. Urbina, Phys. Rev. Lett. 112, 140403 (2014). [less ▲]

Detailed reference viewed: 7 (2 ULg)
See detailCoherent backscattering in the Fock space of a disordered Bose-Hubbard system
Schlagheck, Peter ULg

Conference (2014, June)

We predict a generic signature of quantum interference in many-body bosonic systems resulting in a coherent enhancement of the average return probability in Fock space [1]. This enhancement is robust with ... [more ▼]

We predict a generic signature of quantum interference in many-body bosonic systems resulting in a coherent enhancement of the average return probability in Fock space [1]. This enhancement is robust with respect to variations of external parameters even though it represents a dynamical manifestation of the delicate superposition principle in Fock space. It is a genuine quantum many-body effect which lies beyond the reach of any mean-field approach. Using a semiclassical approach based on interfering paths in Fock space, we calculate the magnitude of the backscattering peak and its dependence on gauge fields that break time-reversal invariance. We confirm our predictions by comparing them to exact quantum evolution probabilities in Bose-Hubbard models, and discuss their relevance in the context of many-body thermalization. We furthermore propose a specific experimental setup in order to detect this many-body coherent backscattering phenomenon with ultracold bosonic atoms. [less ▲]

Detailed reference viewed: 17 (2 ULg)
Full Text
See detailCoherent backscattering in the Fock space of Bose- and Fermi-Hubbard systems
Engl, Thomas; Dujardin, Julien; Tisserond, Emilie et al

Poster (2016, July)

Coherent backscattering generally refers to a significant and robust enhancement of the average backscattering probability of a wave within a disordered medium, which from a semiclassical point of view ... [more ▼]

Coherent backscattering generally refers to a significant and robust enhancement of the average backscattering probability of a wave within a disordered medium, which from a semiclassical point of view arises due to the constructive interference between backscattered trajectories and their time-reversed counterparts. We recently investigated the manifestation of this wave interference phenomenon in the Fock space of a disordered Bose-Hubbard system of finite extent [1], which can potentially be realized using ultracold bosonic atoms within optical lattices. Preparing the atoms in a well-defined Fock state of the lattice and letting the system evolve for a finite time will, for suitable parameters of the system and upon some disorder average over random on-site energies of the lattice, generally give rise to an equidistribution of the occupation probability within the energy shell of the Fock space that corresponds to the initial energy of the system, in accordance with the quantum microcanonical ensemble. We find, however, that the initial state is twice as often encountered as other Fock states with comparable total energy, which is a consequence of coherent backscattering [1]. Most recently, we showed that this phenomenon also arises in spin 1/2 Fermi-Hubbard rings that involve Rashba hopping terms (which combine inter-site hoppings with spin flips and arise from spin-orbit coupling), for which a newly developed semiclassical theory [2] correctly predicts a coherent enhancement of the occupation probabilities of the initial state and its spin-flipped counterpart. Moreover, performing a global spin flip within this Fermi-Hubbard system will give rise to significant spin echo peaks on those two Fock states, which is again a consequence of quantum many-body interference [3]. The semiclassical predictions of these enhancements and peaks are found to be in very good agreement with numerical findings obtained from the exact quantum time evolution within this Fermi-Hubbard system. [1] T. Engl, J. Dujardin, A. Argüelles, P. Schlagheck, K. Richter, and J. D. Urbina, Phys. Rev. Lett. 112, 140403 (2014). [2] T. Engl, P. Plößl, J. D. Urbina, and K. Richter, Theoretical Chemistry Accounts 133, 1563 (2014). [3] T. Engl, J. D. Urbina, and K. Richter, arXiv:1409.5684. [less ▲]

Detailed reference viewed: 22 (3 ULg)
Full Text
See detailCoherent backscattering in the Fock space of Bose- and Fermi-Hubbard systems
Engl, Thomas; Dujardin, Julien; Tisserond, Emilie et al

Poster (2016, May)

Coherent backscattering generally refers to a significant and robust enhancement of the average backscattering probability of a wave within a disordered medium, which from a semiclassical point of view ... [more ▼]

Coherent backscattering generally refers to a significant and robust enhancement of the average backscattering probability of a wave within a disordered medium, which from a semiclassical point of view arises due to the constructive interference between backscattered trajectories and their time-reversed counterparts. We recently investigated the manifestation of this wave interference phenomenon in the Fock space of a disordered Bose-Hubbard system of finite extent [1], which can potentially be realized using ultracold bosonic atoms within optical lattices. Preparing the atoms in a well-defined Fock state of the lattice and letting the system evolve for a finite time will, for suitable parameters of the system and upon some disorder average over random on-site energies of the lattice, generally give rise to an equidistribution of the occupation probability within the energy shell of the Fock space that corresponds to the initial energy of the system, in accordance with the quantum microcanonical ensemble. We find, however, that the initial state is twice as often encountered as other Fock states with comparable total energy, which is a consequence of coherent backscattering [1]. Most recently, we showed that this phenomenon also arises in spin 1/2 Fermi-Hubbard rings that involve Rashba hopping terms (which combine inter-site hoppings with spin flips and arise from spin-orbit coupling), for which a newly developed semiclassical theory [2] correctly predicts a coherent enhancement of the occupation probabilities of the initial state and its spin-flipped counterpart. Moreover, performing a global spin flip within this Fermi-Hubbard system will give rise to significant spin echo peaks on those two Fock states, which is again a consequence of quantum many-body interference [3]. The semiclassical predictions of these enhancements and peaks are found to be in very good agreement with numerical findings obtained from the exact quantum time evolution within this Fermi-Hubbard system. References [1] T. Engl, J. Dujardin, A. Argüelles, P. Schlagheck, K. Richter, and J. D. Urbina, Phys. Rev. Lett. 112, 140403 (2014). [2] T. Engl, P. Plößl, J. D. Urbina, and K. Richter, Theoretical Chemistry Accounts 133, 1563 (2014). [3] T. Engl, J. D. Urbina, and K. Richter, arXiv:1409.5684. [less ▲]

Detailed reference viewed: 10 (3 ULg)