On the robustness of acoustic black hole spectra

We study the robustness of the spectrum emitted by an acoustic black hole by considering series of stationary flows that become either subsonic or supersonic, i.e. when the horizon disappears. We work with the superluminal Bogoliubov dispersion of Bose--Einstein condensates. We find that the spectrum remains remarkably Planckian until the horizon disappears. When the flow is everywhere supersonic, new pair creation channels open. This will be the subject of a forthcoming work.Comment: 4 pages, 2 figure, jpconf.cls; to appear in the proceedings of the Spanish Relativity Meeting ERE201

Stability of Monitoring Weak Changes in Multiply Scattering Media with Ambient Noise Correlation: Laboratory Experiments

Previous studies have shown that small changes can be monitored in a scattering medium by observing phase shifts in the coda. Passive monitoring of weak changes through ambient noise correlation has already been applied to seismology, acoustics and engineering. Usually, this is done under the assumption that a properly reconstructed Green function as well as stable background noise sources are necessary. In order to further develop this monitoring technique, a laboratory experiment was performed in the 2.5MHz range in a gel with scattering inclusions, comparing an active (pulse-echo) form of monitoring to a passive (correlation) one. Present results show that temperature changes in the medium can be observed even if the Green function (GF) of the medium is not reconstructed. Moreover, this article establishes that the GF reconstruction in the correlations is not a necessary condition: the only condition to monitoring with correlation (passive experiment) is the relative stability of the background noise structure

Copulas, multivariate risk-neutral distributions and implied dependence functions

In this paper, we use copulas to define multivariate risk-neutral distributions. We can then derive general pricing formulas for multi-asset options and best possible bounds with given volatility smiles. Finally, we apply the copula framework to define ‘forward-looking ’ indicators of the dependence function between asset returns.

Black hole lasers in Bose-Einstein condensates

We consider elongated condensates that cross twice the speed of sound. In the absence of periodic boundary conditions, the phonon spectrum possesses a discrete and finite set of complex frequency modes that induce a laser effect. This effect constitutes a dynamical instability and is due to the fact that the supersonic region acts as a resonant cavity. We numerically compute the complex frequencies and density-density correlation function. We obtain patterns with very specific signatures. In terms of the gravitational analogy, the flows we consider correspond to a pair of black hole and white hole horizons, and the laser effect can be conceived as a self-amplified Hawking radiation. This is verified by comparing the outgoing flux at early time with the standard black hole radiation.Comment: iopams, 37 pages, 14 figures, 1 table; for associated gif animations, see http://people.sissa.it/~finazzi/bec_bhlasers/movies/ or http://iopscience.iop.org/1367-2630/12/9/095015/media. Published on New. J. Phys. (http://iopscience.iop.org/1367-2630/12/9/095015/). V2: few new comments, modified figure

Laparoscopic adjustable gastric banding in adolescents: Results at two years including psychosocial aspects

BACKGROUND/PURPOSE: Obesity now affects 3%-4% of the pediatric population and contributes to the increase in cardiac mortality in adulthood. Bariatric surgery is the best treatment for weight loss and the obesity-associated comorbidities in adults. We report here our experience of laparoscopic adjustable gastric banding (LAGB) in adolescents. METHODS: The medical charts of the first 16 patients operated on in our center were reviewed. Data were compiled concerning weight loss, physical and biological comorbidities, health-related quality of life (QOL) and surgical complications before surgery and during 24months of follow-up. RESULTS: The maximal pre-operative median body mass index was 43.0kg·m(-2), decreasing to 33.0kg·m(-2) at 2years post-LAGB, which corresponded to a 49.2% excess body weight loss (p<0.001). Most comorbidities (glucose intolerance, hypertension and sleep apnea) resolved within the first year post-LAGB and QOL was improved on the PedsQL™ scales. No severe surgical complications were noted, with only three re-interventions for device failure (2) or band removal (1). CONCLUSION: LAGB is well tolerated in adolescents and shows a beneficial impact on weight loss and obesity-related comorbidities. Associated with global management, it may have a positive impact on patients\u27 QOL and social and psychological status

Confirmation that variants in TTI2 are responsible for autosomal recessive intellectual disability

TTI2 (MIM 614126) has been described as responsible for autosomal recessive intellectual disability (ID; MRT39, MIM:615541) in only two inbred families. Here, we give an account of two individuals from two unrelated outbred families harbouring compound heterozygous TTI2 pathogenic variants. Together with severe ID, progressive microcephaly, scoliosis and sleeping disorder are the most striking features in the two individuals concerned. TTI2, together with TTI1 and TELO2, encode proteins that constitute the triple T heterotrimeric complex. This TTT complex interacts with the HSP90 and R2TP to form a super-complex that has a chaperone function stabilising and maturing a number of kinases, such as ataxia-telangiectasia mutated and mechanistic target of rapamycin, which are key regulators of cell proliferation and genome maintenance. Pathogenic variants in TTI2 logically result in a phenotype close to that caused by TELO2 variants

Toward Forecasting Volcanic Eruptions using Seismic Noise

During inter-eruption periods, magma pressurization yields subtle changes of the elastic properties of volcanic edifices. We use the reproducibility properties of the ambient seismic noise recorded on the Piton de la Fournaise volcano to measure relative seismic velocity variations of less than 0.1 % with a temporal resolution of one day. Our results show that five studied volcanic eruptions were preceded by clearly detectable seismic velocity decreases within the zone of magma injection. These precursors reflect the edifice dilatation induced by magma pressurization and can be useful indicators to improve the forecasting of volcanic eruptions.Comment: Supplementary information: http://www-lgit.obs.ujf-grenoble.fr/~fbrengui/brenguier_SI.pdf Supplementary video: http://www-lgit.obs.ujf-grenoble.fr/~fbrengui/brenguierMovieVolcano.av