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See detailSurfactin: a receptor-independent bacterial elicitor of plant immunity?
Luzuriaga Loaiza, Walter ULg; Legras, Aurelien; Crowet, Jean-Marc ULg et al

Scientific conference (2015, May 13)

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See detailTransport of Bose-Einstein Condensates through Aharonov-Bohm rings
Chrétien, Renaud ULg; Dujardin, Julien ULg; Petitjean, Cyril ULg et al

Poster (2015, May 13)

We study the one-dimensional (1D) transport properties of an ultracold gas of Bose-Einstein condensed atoms through Aharonov-Bohm (AB) rings. Our system consists of a Bose-Einstein condensate (BEC) that ... [more ▼]

We study the one-dimensional (1D) transport properties of an ultracold gas of Bose-Einstein condensed atoms through Aharonov-Bohm (AB) rings. Our system consists of a Bose-Einstein condensate (BEC) that is outcoupled from a magnetic trap into a 1D waveguide which is made of two semi-infinite leads that join a ring geometry exposed to a magnetic flux φ. We specifically investigate the effects of a small atom-atom contact interaction strength on the AB oscillations. The main numerical tools that we use for this purpose are a mean-field Gross-Pitaevskii (GP) description and the truncated Wigner (tW) method. The latter allows for the description of incoherent transport and corresponds to a classical sampling of the evolution of the quantum bosonic many-body state through effective GP trajectories. We find that resonant transmission peaks move with an increasing interaction strength and can be suppressed for sufficiently strong interaction. We also observe that the coherent transmission blockade due to destructive interference at the AB flux φ = π is very robust with respect to the interaction strength. [less ▲]

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See detailJupiter's equatorward auroral features
Dumont, Maïté ULg; Grodent, Denis ULg; Radioti, Aikaterini ULg et al

Conference (2015, May 13)

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See detailGravitational lensing search for dark matter haloes (2)
Biernaux, Judith ULg

Scientific conference (2015, May 13)

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See detailInvestigation on a hydrogen maser cavity in the TE111 mode : first results
Van Der Beken, Emeline ULg; Léonard, Daniel; Counet, Arnaud et al

Poster (2015, May 13)

Results of our preliminary investigation on a hydrogen maser cavity in the unusual TE111 mode are presented. Hydrogen masers use the transition at 1420.405MHz between the two hyperfine levels F = 0 and F ... [more ▼]

Results of our preliminary investigation on a hydrogen maser cavity in the unusual TE111 mode are presented. Hydrogen masers use the transition at 1420.405MHz between the two hyperfine levels F = 0 and F = 1 of the 1s1/2 ground state of the hydrogen atom. In contrast to standard hydrogen maser that exploits the TE011 mode, the TE111 mode allows one to design hydrogen masers with significant reduced dimensions, which represents a huge benefit for space applications and in particular for the global positioning system. In view of a future development of a hydrogen maser in the TE111 mode we performed a thorough analysis of the maser physics for this mode. Different simulations carried out are compared with first measurement results obtained for such a cavity. [less ▲]

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See detailChaotic Bohmian trajectories for the hydrogen atom
Cesa, Alexandre ULg; Struyve, Ward ULg; Martin, John ULg

Poster (2015, May 13)

In Bohmian mechanics, a single-particle quantum system is described in part by its wave function and in part by the actual position of the particle. The trajectory of the latter can be computed using the ... [more ▼]

In Bohmian mechanics, a single-particle quantum system is described in part by its wave function and in part by the actual position of the particle. The trajectory of the latter can be computed using the guiding equation. This equation states that the velocity of the particle is proportional to the usual probability current associated with its wave function. In this work, we study the quantum trajectory of a single particle in a Coulomb potential whose eigenstates are the well known eigenstates of the hydrogen atom. More precisely, we focus on the relation between chaotic Bohmian trajectories and the motion of wave function nodes. At wave function nodes i.e., where the wave function vanishes, the velocity is not defined which generically induces vorticity. In order to probe chaos, we compute Poincaré map and we numerically evaluate Lyapounov exponents, which characterize the divergence of close trajectories as time increases. For the 2d Coulomb potential, although the superposition of two eigenstates with different energies can lead to an arbitrary high number of moving nodes of the wave function, the Bohmian trajectories display no trace of chaos. This absence of chaotic behaviour originates from the existence of a constant of motion. Therefore, the motion and the number of nodes do not constitute a sufficient condition for the emergence of chaos in Bohmian mechanics. For superpositions of more than two eigenstates, there is no constant of motion, there are moving nodes and we find that the Bohmian trajectories are chaotic. [less ▲]

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See detailIs the natural shape of ions in the gas phase spherical ? The allegory of the cave (Plato) applied in mass spectrometry
Far, Johann ULg; Haler, Jean ULg; Kune, Christopher ULg et al

Conference (2015, May 13)

The transfer of ions from solution to gas phase is a critical step to produce « native species ». Coming from a highly solvating medium, ionic species will tend to find new equilibrium conformations in ... [more ▼]

The transfer of ions from solution to gas phase is a critical step to produce « native species ». Coming from a highly solvating medium, ionic species will tend to find new equilibrium conformations in the gas phase. The pathway to reach the thermodynamically stable conformation(s) involves crossing potential barriers according to the type of interactions involved. When these barriers are too high compared to the internal energy of the ions, it may result in a “partial memory” (as structural preservation) of the conformation in solution. In order to evaluate the effect of the solvent evaporation and of the various collision processes encountered by the ions in the mass spectrometer we based our strategy on the determination of deviations from a spherical shape, supposed to be the natural state of ions in the gas phase. [less ▲]

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See detailInteraction of HTLV-1 Tax with minichromosome maintenance proteins modulates viral transcription
Barez, Pierre-Yves ULg; Carpentier, Alexandre ULg; Boxus, Mathieu et al

Poster (2015, May 13)

First human retrovirus discovered, HTLV-1 infects approximately twenty million individuals worldwide. HTLV-1 is the causative agent of different diseases that include adult T-cell leukemia (ATL) and a ... [more ▼]

First human retrovirus discovered, HTLV-1 infects approximately twenty million individuals worldwide. HTLV-1 is the causative agent of different diseases that include adult T-cell leukemia (ATL) and a neurodegenerative disorder called HAM/TSP (Human associated myelopathy/ Tropical spastic paraparesis). We are interested in the mechanisms of transformation by the viral Tax oncoprotein. We previously showed that Tax interacts with the minichromosome maintenance MCM2-7 helicase and affects host cell replication (Boxus et al, 2012 Blood 119:151). In this project, we focused on the role of the MCM2-7 complex in transcription. We first show by chromatin immunoprecipitation that the MCM2-7 is recruited onto the 5'-LTR promoter. The 5’-LTR does however not act as a DNA replication origin. In contrast, MCM2-7 activates viral transcription as revealed by luciferase reporter assays. Interaction between Tax and MCM2-7 also affect expression of cellular genes. Together, our data thus demonstrate that the viral promoter is not a replication origin and that interaction between Tax and MCM2-7 is involved in the viral transcription. [less ▲]

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See detailThe utility of Google Scholar when searching geographical literature: comparison with three commercial bibliographic databases
Stirbu, Simona ULg; Thirion, Paul ULg; Schmitz, Serge ULg et al

in Journal of Academic Librarianship (2015), 41(3), 322-329

This study aims to highlight what benefits, if any, Google Scholar (GS) has for academic literature searches in the field of geography, compared to three commercial bibliographic databases: Web of Science ... [more ▼]

This study aims to highlight what benefits, if any, Google Scholar (GS) has for academic literature searches in the field of geography, compared to three commercial bibliographic databases: Web of Science (WoS) and FRANCIS (multidisciplinary databases) and GeoRef (specialized in geosciences). To ensure a valid comparison, identical bibliographic searches were applied using each of the four bibliographic tools. To exclude automatic variations of the ten keywords tested, they were placed between quotation marks and searched only in the “title” field of the respective search tools’ interfaces. The results were limited to bibliographic references published from 2005 to 2009. In order to assess the repeatability of the results, the exact same process was repeated monthly between November 2010 and July 2011. Initially the whole set of results was analyzed, after which the search results for two keywords (selected since they yielded a manageable number of results) were studied in more detail. The results indicate that GS search results show a large degree of overlap with those of the other databases but, moreover, yield numerous unique hits, which should be useful to researchers in both the fields of human and physical geography. GS leads the other tools widely on number of results, independently of keyword, subfield, year of publication, or time of search. [less ▲]

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See detailAnticoherence of multiqubit symmetric states
Baguette, Dorian ULg; Bastin, Thierry ULg; Martin, John ULg

Conference (2015, May 13)

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See detailMagneto-optical trapping of iron atoms
Crauwels, Justine ULg; Huet, Nicolas ULg; Krins, Stéphanie ULg et al

Poster (2015, May 13)

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See detailGrowth factor-induced angiogenesis requires uPAR on endothelial cells
Paques, Cécile ULg

Poster (2015, May 13)

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See detailDesign and synthesis of PET-probes targeting AMPA subtype receptors
Deverdenne, François ULg; Claes, Giselle ULg; Goffin, Eric ULg et al

Poster (2015, May 13)

The AMPA subtype of glutamatergic receptors is the main actor in the fast excitatory neurotransmission in the mammalian central nervous system. These receptors are involved in the expression and the ... [more ▼]

The AMPA subtype of glutamatergic receptors is the main actor in the fast excitatory neurotransmission in the mammalian central nervous system. These receptors are involved in the expression and the maintenance of the long-term potentiation, a phenomenon closely linked to cognitive and memorization processes. Based on experimental data, it also appears that glutamatergic systems are involved in several pathological diseases. For instance, a lack of glutamatergic neurotransmission is observed in cognitive disorders or schizophrenia and an excessive activity is observed in Parkinson or Huntington diseases. The in vivo study of glutamate receptors mapping and its evolution appears to be an essential step for a better understanding of its implications. However, according to the literature, design of such a probe remains difficult due to the lack of specificity of the probes. Taking into account the potential in vitro and in vivo activity and specificity of benzothiadizine dioxides (BTDs) acting as AMPA positive allosteric modulators, we are investing the development of new compounds of this class radiolabeled with a fluorine-18 atom. Hence, we are currently developing new series of BTDs characterized by the presence of a fluorine atom and a 7-phenoxy-substituent that are expected to be more active and more specific. Finally, pharmacological tests to evaluate the best candidates for the radiochemical synthesis and in vivo evaluations are currently in progress. [less ▲]

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See detailAn encapsulation-dehydration method for the long-term storage of cyanobacterial strains in the BCCM/ULC collection.
Crahay, Charlotte ULg; Mari, Maude; Wilmotte, Annick ULg

Poster (2015, May 13)

Long-term genetic and functional stability is a fundamental requirement for the maintenance of microorganisms. Cryopreservation is the preferred method for the long-term storage of many micro-organisms ... [more ▼]

Long-term genetic and functional stability is a fundamental requirement for the maintenance of microorganisms. Cryopreservation is the preferred method for the long-term storage of many micro-organisms, including cyanobacteria. The BCCM/ULC collection currently holds over 200 cyanobacterial strains as living cultures, but only 62 are maintained in a cryo-preserved state. The main limiting factors are the low levels of survival of some strains, as well as the long periods required to recover from cryopreservation, and thus the inability to rapidly deliver strains to clients.. The BRAIN-be project PRESPHOTO (preservation of photosynthetic micro-algae in the BCCM collections) (www.presphoto.ulg.ac.be) aims to improve the preservation of cyanobacterial and diatoms in the BCCM/ULC and BCCM/DCG collections, respec-tively. The encapsulation-dehydration is often considered as a promising alternative to the traditional cryopreservation method for recalcitrant microalgal strains. In this technique, cyanobacterial cultures are entrapped in calcium-alginate beads, osmotically dehydrated (traditionally with sucrose solutions), then evaporatively desiccated in a sterile air flow, or over silica gel and subsequently cryopreserved. In this study, the encapsulation-dehydration method was evaluated as potential long-term preservation technique of cyanobacterial strains. The effects of several factors on the viability of 4 strains have been investigated to determine which are the most important for the successful cryopreservation. In particular, several cryoprotectants (i.e. sucrose, PEG or mannitol), methods of beads dehydration (i.e. under a laminar flow or with silica gel) were tested. We have also compared storage at -70°C and in liquid nitrogen (-196oC). A pre-cultivation step in KCl was also tested for its ability to enhance desiccation tolerance. In addition, the use of alginate dissolution buffer following thawing was also considered. In the final phase of the project, the selected cryopreservation protocols will be tested on a large set of strains. In addition, an independent validation of the protocols will be also performed by both partners of the project (BCCM/DCG and the Culture Collection of Algae and Protozoa). [less ▲]

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See detailFlemish nationalism and hip-hop in Belgium Politics v/s music between ethnicity and class
Mazzola, Alessandro ULg

Scientific conference (2015, May 12)

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See detailValorisation de la biomasse par fermentation : biométhanisation et biohydrogène
Hiligsmann, Serge ULg

Scientific conference (2015, May 12)

Detailed reference viewed: 55 (3 ULg)