1,321 research outputs found
M. Maruani — Les mécomptes du chômage
No full textMeron Monique. M. Maruani — Les mécomptes du chômage. In: Population, 58ᵉ année, n°1, 2003. pp. 157-159
M. Maruani — Les mécomptes du chômage
No full textMeron Monique. M. Maruani — Les mécomptes du chômage. In: Population, 58ᵉ année, n°1, 2003. pp. 157-159
Meron ground states of quantum Hall droplets
Get PDFWe argue that topological meron excitations, which are in a strong coupling phase ͑bound in pairs͒ in infinite quantum Hall ferromagnets, become deconfined in finite-size quantum Hall systems. Although effectively for larger systems meron energy grows with the size of the system, when gyromagnetic ratio is small meron becomes the lowest-lying state of a quantum Hall droplet. This comes as a consequence of the many-body correlations built in the meron construction that minimize the interaction energy. We demonstrate this by using mean-field ansatzes for meron wave function. The ansatzes will enable us to consider much larger system sizes than in the previous work ͓A. Petković and M. V. Milovanović, Phys. Rev. Lett. 98, 066808 ͑2007͔͒, where fractionalization into merons was introduced
Topology of spin meron pairs in coupled Ni/Fe/Co/Cu(001) disks
No full textThe meron is a special topological object that carries only one-half of the topological charge unit. In condensed matter physics, a spin meron corresponds to one-half of a spin skyrmion. As compared to the many fascinating topological properties of skyrmion materials, little is known of the properties of spin merons especially about their formation. It was confirmed only recently that hedgehog merons could exist in pairs with opposite helicities via a spin flux closure. However, it is unclear whether a single hedgehog meron could ever exist by pairing with another type of meron. Using element-resolved magnetic imaging measurements on epitaxial trilayer disks, we show that a spin meron with a full range of helicity, including the hedgehog meron, can be stabilized by pairing with another vortex meron with a fine tuning of the magnetic coupling between the two merons. Furthermore, the meron divergence is fully controlled by the polarity of the vortex meron, independent of the vortex helicity.National Science Foundation [DMR-1504568]; Future Materials Discovery Program through the National Research Foundation of Korea [2015M3D1A1070467]; Science Research Center Program through the National Research Foundation of Korea [2015R1A5A1009962]; Office of Science, Office of Basic Energy Sciences; US Department of Energy [DE-AC02-05CH11231]SCI(E)[email protected]
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An Analysis of the Mt. Meron Seismic Array
Get PDFWe have performed a quick analysis of the Mt. Meron seismic array to monitor regional seismic events in the Middle East. The Meron array is the only current array in the Levant and Arabian Peninsula and, as such, might be useful in contributing to event location, identification, and other analysis. Here, we provide a brief description of the array and a review of the travel time and array analysis done to assess its performance
Creation and annihilation of topological meron pairs in in-plane magnetized films
Get PDFMerons which are topologically equivalent to one-half of skyrmions can exist only in pairs or groups in two-dimensional (2D) ferromagnetic (FM) systems. The recent discovery of meron lattice in chiral magnet Co8Zn9Mn3 raises the immediate challenging question that whether a single meron pair, which is the most fundamental topological structure in any 2D meron systems, can be created and stabilized in a continuous FM film? Utilizing winding number conservation, we develop a new method to create and stabilize a single pair of merons in a continuous Py film by local vortex imprinting from a Co disk. By observing the created meron pair directly within a magnetic field, we determine its topological structure unambiguously and explore the topological effect in its creation and annihilation processes. Our work opens a pathway towards developing and controlling topological structures in general magnetic systems without the restriction of perpendicular anisotropy and Dzyaloshinskii–Moriya interaction. © 2019, The Author(s).TRU
The effect of prefrontal transcranial direct current stimulation on attention network function in healthy volunteers
Get PDFObjectives: The effect of acute transcranial direct current stimulation (tDCS) on cortical attention networks remains unclear. We examined the effect of 20 minutes of 2mA prefrontal dorsolateral prefrontal cortex (DLPFC) tDCS (bipolar balanced montage) on the efficiency of alerting, orienting and executive attention networks measured by the attention network test (ANT). Materials and Methods: A between-subjects stratified randomised design compared active tDCS vs. sham tDCS on attention network function in healthy young adults.Results: Executive attention was greater following active vs. sham stimulation (d= 0.76) in the absence of effects on alerting, orienting or global RT or error rates. Group differences were not moderated by state-mood. Conclusion(s): 20 minutes of active 2mA tDCS over left DLPFC is associated with greater executive attention in healthy humans.<br/
Modelling the survival of bacteria in drylands: the advantage of being dormant
No full textWe introduce a simple mathematical model for the description of
`dormancy', a survival strategy used by some bacterial populations that
are intermittently exposed to external stress. We focus on the case of
the cyanobacterial crust in drylands, exposed to severe water shortage,
and compare the fate of ideal populations that are, respectively,
capable or incapable of becoming dormant. The results of the simple
model introduced here indicate that under a constant, even though low,
supply of water the dormant strategy does not provide any benefit and it
can, instead, decrease the chances of survival of the population. The
situation is reversed for highly intermittent external stress, due to
the presence of prolonged periods of dry conditions intermingled with
short periods of intense precipitation. In this case, dormancy allows
for the survival of the population during the dry periods. In contrast,
bacteria that are incapable of turning into a dormant state cannot
overcome the difficult times. The model also rationalizes why dormant
bacteria, such as those composing the cyanobacterial crust in the
desert, are extremely sensitive to other disturbances, such as trampling
cattle
Thème 4. La mobilité des salariés de l'Etat. Discussion sur les communications de M. Méron, C. Agulhon et J. Pihan
No full textTerrier Christophe, Meron Monique, Faidutti Anne-Marie, Laget Michel. Thème 4. La mobilité des salariés de l'Etat. Discussion sur les communications de M. Méron, C. Agulhon et J. Pihan . In: Espace, populations, sociétés, 1988-3. La population face à l'emploi - Population and work opportunities. p. 554
Diversity of vegetation patterns and desertification
No full textA new model for vegetation patterns is introduced. The model reproduces
a wide range of patterns observed in water-limited regions, including
drifting bands, spots, and labyrinths. It predicts transitions from bare
soil at low precipitation to homogeneous vegetation at high
precipitation, through intermediate states of spot, stripe, and hole
patterns. It also predicts wide precipitation ranges where different
stable states coexist. Using these predictions we propose a novel
explanation of desertification phenomena and a new approach to
classifying aridity
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