35 research outputs found
Dynamics of Sleep-Wake Transitions During Sleep
We study the dynamics of the awakening during the night for healthy subjects
and find that the wake and the sleep periods exhibit completely different
behavior: the durations of wake periods are characterized by a scale-free
power-law distribution, while the durations of sleep periods have an
exponential distribution with a characteristic time scale. We find that the
characteristic time scale of sleep periods changes throughout the night. In
contrast, there is no measurable variation in the power-law behavior for the
durations of wake periods. We develop a stochastic model which agrees with the
data and suggests that the difference in the dynamics of sleep and wake states
arises from the constraints on the number of microstates in the sleep-wake
system.Comment: Final form with some small corrections. To be published in
Europhysics Letters, vol. 57, issue no. 5, 1 March 2002, pp. 625-63
Nonlinear Lattice Waves in Random Potentials
Localization of waves by disorder is a fundamental physical problem
encompassing a diverse spectrum of theoretical, experimental and numerical
studies in the context of metal-insulator transition, quantum Hall effect,
light propagation in photonic crystals, and dynamics of ultra-cold atoms in
optical arrays. Large intensity light can induce nonlinear response, ultracold
atomic gases can be tuned into an interacting regime, which leads again to
nonlinear wave equations on a mean field level. The interplay between disorder
and nonlinearity, their localizing and delocalizing effects is currently an
intriguing and challenging issue in the field. We will discuss recent advances
in the dynamics of nonlinear lattice waves in random potentials. In the absence
of nonlinear terms in the wave equations, Anderson localization is leading to a
halt of wave packet spreading.
Nonlinearity couples localized eigenstates and, potentially, enables
spreading and destruction of Anderson localization due to nonintegrability,
chaos and decoherence. The spreading process is characterized by universal
subdiffusive laws due to nonlinear diffusion. We review extensive computational
studies for one- and two-dimensional systems with tunable nonlinearity power.
We also briefly discuss extensions to other cases where the linear wave
equation features localization: Aubry-Andre localization with quasiperiodic
potentials, Wannier-Stark localization with dc fields, and dynamical
localization in momentum space with kicked rotors.Comment: 45 pages, 19 figure
Superfluidity and collective oscillations of trapped Bose-Einstein condensates in a periodical potential
Based on a unified theoretical treatment of the 1D Bogoliubov-de Genes
equations, the superfluidity phenomenon of the Bose-Einstein condensates (BEC)
loaded into trapped optical lattice is studied. Within the perturbation regime,
an all-analytical framework is presented enabling a straightforward
phenomenological mapping of the collective excitation and oscillation character
of a trapped BEC where the available experimental configurations also fit.Comment: 5 pages and 2 Figs, some errors have been corrected in versions
Supportive care in the acute phase of Stevens-Johnson syndrome and toxic epidermal necrolysis : an international, multidisciplinary Delphi-based consensus
Background Supportive care is the cornerstone of management of adult and paediatric Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). However, consensus on the modalities of supportive care is lacking. Objectives Our aim in this international multicentric Delphi exercise was to establish a multidisciplinary expert consensus to standardize recommendations regarding supportive care in the acute phase of SJS/TEN. Methods Participants were sent a survey via the online tool SurveyMonkey, consisting of 103 statements organized into 11 topics: multidisciplinary team composition, suspect drug management, infection prevention, fluid resuscitation and prevention of hypothermia, nutritional support, pain and psychological distress management, management of acute respiratory failure, local skincare, ophthalmological management, management of other mucosa, and additional measures. Participants evaluated the level of appropriateness of each statement on a scale of 1 (extremely inappropriate) to 9 (extremely appropriate). The results were analysed according to the RAND/UCLA Appropriateness Method. Results Forty-five participants from 13 countries (on three continents) participated. After the first round, a consensus was obtained for 82.5% of the 103 initially proposed statements. After the second round, a final consensus was obtained for 102 statements. Conclusions We have reached an international Delphi-based consensus on best supportive care practice for SJS/TEN. Our expert consensus should help guide physicians in treating patients with SJS/TEN and thereby improve short-term prognosis and the risk of sequelae.Peer reviewe
Real-time reconstruction of the strong-field driven dipole response
Using ultrashort and phase-locked laser pulses, combined with an in situ measurement of a reference pulse, we present a method capable of retrieving the nonlinearly perturbed time-dependent response function of a quantum system driven by strong electric fields directly from spectroscopic absorption data with high precision
Nrf2-mediated antioxidant defense and peroxiredoxin 6 are linked to biosynthesis of palmitic acid ester of 9-hydroxystearic acid
Fatty acid esters of hydroxy fatty acids (FAHFAs) are lipid mediators with promising anti-diabetic and anti-inflammatory properties that are formed in white adipose tissue (WAT) vialipogenesis, but their biosynthetic enzymes are unknown. Using a combination of lipidomics in WAT, QTL mapping and correlation analyses in rat BXH/HXB recombinant inbred strains, and response to oxidative stress in murine models, we elucidated the potential pathway of biosynthesis of several FAHFAs.Comprehensive analysis of WAT samples identified ∼160 regioisomers documenting the complexity of this lipid class. The linkage analysis highlighted several members of Nuclear factor, erythroid 2-like 2 ()-mediated antioxidant defense system (), lipid-handling proteins () and family of Flavin Containing Monooxygenase () as the positional candidate genes. Transgenic expression ofand deletion ofgenes resulted in reduction of palmitic acid ester of 9-hydroxystearic acid (9-PAHSA) and 11-PAHSA levels, while oxidative stress induced by an inhibitor of glutathione synthesis increased PAHSA levels nonspecifically.Our results indicate that the synthesis of FAHFAscarbohydrate-responsive element-binding protein (ChREBP)-drivenlipogenesis depends on the adaptive antioxidant system and suggest that FAHFAs may link activity of this system with insulin sensitivity in peripheral tissues