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Search Results: 1 - 10 of 1149 matches for " Iris Leenaerts "
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The Atonal Proneural Transcription Factor Links Differentiation and Tumor Formation in Drosophila
Wouter Bossuyt,Natalie De Geest,Stein Aerts,Iris Leenaerts,Peter Marynen,Bassem A. Hassan
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000040
Abstract: The acquisition of terminal cell fate and onset of differentiation are instructed by cell type–specific master control genes. Loss of differentiation is frequently observed during cancer progression, but the underlying causes and mechanisms remain poorly understood. We tested the hypothesis that master regulators of differentiation may be key regulators of tumor formation. Using loss- and gain-of-function analyses in Drosophila, we describe a critical anti-oncogenic function for the atonal transcription factor in the fly retina, where atonal instructs tissue differentiation. In the tumor context, atonal acts by regulating cell proliferation and death via the JNK stress response pathway. Combined with evidence that atonal's mammalian homolog, ATOH1, is a tumor suppressor gene, our data support a critical, evolutionarily conserved, function for ato in oncogenesis.
The Atonal Proneural Transcription Factor Links Differentiation and Tumor Formation in Drosophila
Wouter Bossuyt,Natalie De Geest,Stein Aerts,Iris Leenaerts,Peter Marynen,Bassem A Hassan
PLOS Biology , 2009, DOI: 10.1371/journal.pbio.1000040
Abstract: The acquisition of terminal cell fate and onset of differentiation are instructed by cell type–specific master control genes. Loss of differentiation is frequently observed during cancer progression, but the underlying causes and mechanisms remain poorly understood. We tested the hypothesis that master regulators of differentiation may be key regulators of tumor formation. Using loss- and gain-of-function analyses in Drosophila, we describe a critical anti-oncogenic function for the atonal transcription factor in the fly retina, where atonal instructs tissue differentiation. In the tumor context, atonal acts by regulating cell proliferation and death via the JNK stress response pathway. Combined with evidence that atonal's mammalian homolog, ATOH1, is a tumor suppressor gene, our data support a critical, evolutionarily conserved, function for ato in oncogenesis.
Transceiver Design for Multiband OFDM UWB
Leenaerts DMW
EURASIP Journal on Wireless Communications and Networking , 2006,
Abstract: Ultra-wideband (UWB) is an emerging broadband wireless technology enabling data rates up to Mbps. This paper provides an overview of recent design approaches for several circuit functions that are required for the implementation of multiband OFDM UWB transceivers. A number of transceiver and synthesizer architectures that have been proposed in literature will be reviewed. Although the technology focus will be on CMOS, also some design techniques implemented in BiCMOS technologies will be presented.
Adsorption of H2O, NH3, CO, NO2, and NO on graphene: A first-principles study
O. Leenaerts,B. Partoens,F. M. Peeters
Physics , 2007, DOI: 10.1103/PhysRevB.77.125416
Abstract: Motivated by the recent realization of graphene sensors to detect individual gas molecules, we investigate the adsorption of H2O, NH3, CO, NO2, and NO on a graphene substrate using first-principles calculations. The optimal adsorption position and orientation of these molecules on the graphene surface is determined and the adsorption energies are calculated. Molecular doping, i.e. charge transfer between the molecules and the graphene surface, is discussed in light of the density of states and the molecular orbitals of the adsorbates. The efficiency of doping of the different molecules is determined and the influence of their magnetic moment is discussed.
Graphene: a perfect nanoballoon
O. Leenaerts,B. Partoens,F. M. Peeters
Physics , 2008, DOI: 10.1063/1.3021413
Abstract: We have performed a first-principles density functional theory investigation of the penetration of helium atoms through a graphene monolayer with defects. The relaxation of the graphene layer caused by the incoming helium atoms does not have a strong influence on the height of the energy barriers for penetration. For defective graphene layers, the penetration barriers decrease exponentially with the size of the defects but they are still sufficiently high that very large defects are needed to make the graphene sheet permeable for small atoms and molecules. This makes graphene a very promising material for the construction of nanocages and nanomembranes.
Paramagnetic adsorbates on graphene: a charge transfer analysis
O. Leenaerts,B. Partoens,F. M. Peeters
Physics , 2008, DOI: 10.1063/1.2949753
Abstract: We introduce a modified version of the Hirshfeld charge analysis method and demonstrate its accurateness by calculating the charge transfer between the paramagnetic molecule NO2 and graphene. The charge transfer between paramagnetic molecules and a graphene layer as calculated with ab initio methods can crucially depend on the size of the supercell used in the calculation. This has important consequences for adsorption studies involving paramagnetic molecules such as NO2 physisorbed on graphene or on carbon nanotubes.
Evaluation of process management of postpartum hemorrhage due to uterine atony  [PDF]
Iris Holzer, Rainer Lehner
Open Journal of Obstetrics and Gynecology (OJOG) , 2013, DOI: 10.4236/ojog.2013.37093
Abstract:

Objective: To evaluate the management process and the guidelines for management of postpartum hemorrhage due to uterine atony at the General Hospital Vienna, Medical University Vienna. Material and Methods: A retrospective analysis was carried out on all 24 cases of postpartum hemorrhage due to uterine atony with an estimated blood loss of more than 800 mL, in which standardized guidelines were obtained. We included all women who gave birth at the General Hospital of Vienna, the Medical University Vienna, during the period from January 1st 2003 and December 31st 2009 and who suffered blood loss 800 mL at minimum due to uterine atony. Results: The guidelines were in use for 14% - 71%. The average blood loss of the 24 cases with uterine atony was 1342 mL. Conclusion: The management process of postpartum hemorrhage due to uterine atony deviates from the hospital’s guidelines in many cases.

First-principles investigation of bilayer fluorographene
Jozef Sivek,Ortwin Leenaerts,Bart Partoens,Francois Peeters
Physics , 2011, DOI: 10.1021/jp3027012
Abstract: \textit{Ab initio} calculations within the density functional theory formalism are performed to investigate the stability and electronic properties of fluorinated bilayer graphene (bilayer fluorographene). A comparison is made to previously investigated graphane, bilayer graphane, and fluorographene. Bilayer fluorographene is found to be a much more stable material than bilayer graphane. Its electronic band structure is similar to that of monolayer fluorographene, but its electronic band gap is significantly larger (about 1 eV). We also calculate the effective masses around the $\Gamma$-point for fluorographene and bilayer fluorographene and find that they are isotropic, in contrast to earlier reports. Furthermore, it is found that bilayer fluorographene is almost as strong as graphene, as its 2D Young's modulus is approximately 300 $\mathrm{N} \mathrm{m}^{-1}$.
GraphAne: From Synthesis to Applications
H. Sahin,O. Leenaerts,S. K. Singh,F. M. Peeters
Physics , 2015,
Abstract: Atomically thin crystals have recently been the focus of attention in particular after the synthesis of graphene, a monolayer hexagonal crystal structure of carbon. In this novel material class the chemically derived graphenes have attracted tremendous interest. It was shown that although bulk graphite is a chemically inert material, the surface of single layer graphene is rather reactive against individual atoms. So far, synthesis of several graphene derivatives have been reported such as hydrogenated graphene "graphane" (CH), fluorographene (CF) and chlorographene (CCl). Moreover, the stability of bromine and iodine covered graphene were predicted using computational tools. Among these derivatives, easy synthesis, insulating electronic behavior and reversibly tunable crystal structure of graphane make this material special for future ultra-thin device applications. This overview, surveys structural, electronic, magnetic, vibrational and mechanical properties of graphane. We also present a detailed overview of research efforts devoted to the computational modeling of graphane and its derivatives. Furthermore recent progress in synthesis techniques and possible applications of graphane are reviewed as well.
Adsorption of titanium and titanium dioxide on graphene: n and p-type doping
Jozef Sivek,Ortwin Leenaerts,Bart Partoens,Francois Peeters
Physics , 2013,
Abstract: Ab initio calculations within the density-functional theory formalism are performed to investigate the ground state, electric charge doping, and electronic properties of titanium and titanium dioxide monolayers adsorbed on a graphene surface. A new ground state structrure of Ti monolayer adsorbed on graphene is reported which is shown to be stable up to T = 500 K. Effects due to lower and higher Ti adatoms coverage are studied. We find that the adsorbed Ti provides a strong n-type doping which supports recent experimental observations. On the other hand, TiO_2 can induce both p- and n-type doping in the carbon monolayer depending on whether oxygen or titanium atoms are closest to the substrate. We identify the structures which are responsible for the experimentally observed autocompensation mechanism that leads to the reversion of adsorbate effects after oxidation of the adsorbed Ti.
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